281 Matching Annotations
  1. Last 7 days
    1. In recent experiments, Dienwiebel et al. (8) observed friction reduction to vanishingly small values, depending on the degree of commensurability between the graphene flakes and the extended graphite surface

      The mechanism of superlubricity at the sliding interfaces of materials is studied. Dienwiebel and co-researchers have investigated the superlubricity of graphite using a home built frictional force microscope. They have also investigated the role of incommensurability in the origin of the ultralow friction of graphite.

    2. with the previously observed low-friction performance of DLC against DLC (fig. S14) (12)

      Diamond like carbon (DLC) film is a widely researched material to combat friction and wear in a number of applications, owing to its impressive tribological properties and low deposition costs. Tribological properties of DLC films sliding against each other are investigated and they are found to display super low friction under specific conditions.

    3. Even a modest 20% reduction in friction can substantially affect cost economics in terms of energy savings

      Moving mechanical assemblies’ failure due to friction and wear are a major concern in today's world. Different types of lubricants are employed to minimize friction. Though this helps to improve the lifetime of mechanical systems, researchers quest for a perfect lubricant to achieve lowest friction and wear possible with no harmful additives or chemicals.

  2. Mar 2019
    1. Stimulation of anorexigenic proopiomelanocortin (POMC) cells in the hypothalamic arcuate nucleus leads to a reduction in feeding slowly over the succeeding 24 hours, whereas stimulation of orexigenic hypothalamic neurons expressing agouti-related peptide (AgRP) leads to what has previously been considered to be a rapid increase in feeding with mean latency to eat of 6.1 min (range: 1.9 to 13.8 min) (19).

      The arcuate nucleus, a subregion of the hypothalamus has been shown to be a very important brain region that controls food intake

      Neurons within this region have been shown to control feeding in a reciprocal manner. POMC-expressing neurons are activated by satiety signals are reduce food intake while AgRP-expressing neurons are activated by starvation and increase food intake.

      These neurons have been proposed to be the neural substrate for satiety and hunger respectively.

    1. Consistent with the prediction of Mo et al. (25), we found that the friction force depends linearly on the number of atoms that chemically interact across the contact

      The application of macroscopic laws of friction to the nanoscale region remained controversial. Mo and his team used molecular dynamics simulations to study friction laws in dry nanoscale contacts. They have investigated the effect of number of atoms in chemical contact in friction and reported the relationship between contact area and friction force at the nanoregime.

  3. Feb 2019
    1. To date, superlubricity has been primarily realized in a limited number of experiments involving atomically smooth and perfectly crystalline materials (2–5) and supported by theoretical studies (6, 7).

      Research in superlubricity is gaining interest due to its potential applications in mechanical systems to reduce the friction and wear related failures. Various researchers proposed different materials to achieve near zero friction. Eventhough these materials shows some promise, most materials are perfectly crystalline (which is not the case in real life) and the effect occurs mostly at the nanoscale regime.

    2. In recent studies at the nano- and macroscale, graphene has shown a potential to substantially lower friction (16–18) and wear (19–21) under specific conditions

      Materials with perfect atomic structures and long periodicity are traditionally sought for superlubricity. Carbon compounds such as carbon nanotubes, graphite and graphene are investigated for this purpose. One concern is the difficulty in attaining sustainable superlubricity at the engineering scale.

    3. The π* peak (at ~285 eV) in the carbon K-edge represents a small fraction of sp2 bonded carbon owing to the presence of the few layers of graphene wrapped around the nanodiamond, which is similar to the disordered carbon shell observed previously in detonated nanodiamonds (23)

      The structural analysis of graphene wrapped nanodiamonds by Electron energy loss spectra reported in this study are analogous to the previously reported structure of detonated nanodiamonds by other researchers.

    4. The contact area, which is proportional to the number of interacting atoms, reduces by 40 to 50% during (26) this period.

      Size plays a major role in superlubricity and many researchers have investigated the dependence of size of materials in friction reduction. Liu and co-workers reported one such size dependent study of superlubricity on graphite. They have detailed the probability percentages of superlubric state for different contact areas and also the mechanism of superlubricity (self retraction) of graphite layers.

    1. It also provides the interviewer with an opportunity to feel smart and validate that “they’ve still got it” and that they aren’t themselves an imposter, by critically examining the work of an outsider who wants in.

      That's the point. How can one interviewer assume to be more competent than the interviewed or assume to be able to judge objectively some other's work?

      Interviewers should start from a place of humbleness and understand they can't spot a person quickly.

      Getting to know and trust somebody is a process that requires time; that's true for any kind of human relationship. It can just start with faith, plus a trial period. There's no shortcut that can keep the same judging reliability of a judgment during time.

    1. Reviving Work Ethic in America

      From the title of the article it's apparent that in the opinion of the author there is need for reviving work ethic in America.

  4. Jan 2019
    1. For Fasting and Football, a Dedicated Game Plan

      We're at it again friends. This time, as you annotate, concentrate on the moves you see--even if you can't name them--and how they work to produce an effect on you the reader.

    1. To him it was chiefly the diurnal and annual variations of the temperature that were lessened by this circumstance.

      The amount of incoming energy from the sun changes drastically between night and day, and varies throughout the year, yet these variations don't affect Earth's surface temperatures as much as would be expected. Tyndall linked the ability of the atmosphere to absorb infrared radiation (heat) to this dampening of temperature variation.

    1. The urgency of time may make it too onerous forthe extra effort of articulating actions as they are beingperformed, yet most emergency response requires somecommunication.

      Interaction of time (tempo/pace) and breakdowns in articulation work.

    2. Explicitly articulated narratives mayalso make clearer that multiple sequences of actions maybe occurring simultaneously, thus resolving role conflictsby allowing multiple ways to accomplish a task

      Evokes Schmidt and Bannon's articulation work in CSCW.

    1. Experimentation, the third affordance, refers to theuse of technology to encourage participants to try outnovel ideas.

      Definition of experimentation.

      Describes the use of comment/feedback boxes, ratings, polls, etc. to generate ideas for new coordination workflows, design ideas, workarounds, etc.

    2. Recombinability refers to forms of technology-enabled action where individual contributors build oneach others’ contributions.

      Definition of recombinability.

      Cites Lessig in describing recombinability "as both a technology design issue and a community governance principle" for reusing/remixing/recombining knowledge

    3. Reviewability refers to the enactment of technology-enabled new forms of working in which participantsare better able to view and manage the content offront and back narratives over time (West and Lakhani2008). By allowing participants to easily and collab-oratively review a range of ideas, technology-affordedreviewability helps the community respond to tensionsin disembodied ideas, because the reviews can provideimportant contextual information for building on others’ideas.

      Definition of reviewability.

      Faraj et al offer the example of Wikipedia edit log to track changes.

    4. Technology platforms used by OCs can providea number of affordances for knowledge collabora-tion, three of which we mention here: reviewability,recombinability, and experimentation. These affordancesevolve as new participants provide new ways to use thetechnologies, new social norms are developed around thetechnology affordances, and new needs for fresh affor-dances are identified.

      Ways that technology affordances can influence/motivate change in social coordination practices.

    5. Given the fluid nature of OCsand their rapidly evolving technology platforms, and inline with calls to avoid dualistic thinking about tech-nology (Leonardi and Barley 2008, Markus and Silver2008, Orlikowski and Scott 2008), we suggest technol-ogy affordance as a generative response, one that viewstechnology, action, and roles as emergent, inseparable,and coevolving. Technology affordances offer a relationalperspective on human action, where neither the technol-ogy nor the actor is dominant in the sense that the tech-nology does not define what is possible for the actor todo, nor is the actor free from the limitations of the tech-nological environment. Instead, possibilities for actionemerge from the reciprocal interaction between actor andartifact (Gibson 1979, Zammuto et al. 2007). Thus, anaffordance perspective focuses on the organizing actionsthat are afforded by technology artifacts.

      Interesting perspective on how technology affordances are a generative response to coordination tensions.

    6. third response to manage tensions is to promoteknowledge collaboration by enacting dynamic bound-aries. In social sciences, although boundaries divide anddisintegrate collectives, they also coordinate and inte-grate social action (Bowker and Star 1999, Lamont andMolnár 2002). Fluidity brings the need for flexible andpermeable boundaries, but it is not only the propertiesof the boundaries but also their dynamicity that helpmanage tensions.

      Cites Bowker and Star

      Good examples of how boundaries co-evolve and take on new meanings follow this paragraph.

    7. We have observed in OCs that no single narrative isable to keep participants informed about the current stateof the OC with respect to each tension. These commu-nities seem to develop two different types of narratives.Borrowing from Goffman (1959), we label the two nar-ratives the “front” and the “back” narratives.

      Cites Goffman and the performative vs invisible aspects of social coordination work.

    8. Based on our collective research on to date, we haveidentified that as tensions ebb and flow, OCs use (or,more precisely, participants engage in) any of the fourtypes of responses that seem to help the OC be gen-erative. The first generative response is labeledEngen-dering Roles in the Moment. In this response, membersenact specific roles that help turn the potentially negativeconsequences of a tension into positive consequences.The second generative response is labeledChannelingParticipation. In this response, members create a nar-rative that helps keep fluid participants informed ofthe state of the knowledge, with this narrative havinga necessary duality between a front narrative for gen-eral public consumption and a back narrative to airthe differences and emotions created by the tensions.The third generative response is labeledDynamicallyChanging Boundaries. In this response, OCs changetheir boundaries in ways that discourage or encouragecertain resources into and out of the communities at cer-tain times, depending on the nature of the tension. Thefourth generative response is labeledEvolving Technol-ogy Affordances. In this response, OCs iteratively evolvetheir technologies in use in ways that are embedded by,and become embedded into, iteratively enhanced socialnorms. These iterations help the OC to socially and tech-nically automate responses to tensions so that the com-munity does not unravel.

      Productive responses to experienced tensions.

      Evokes boundary objects (dynamically changing boundaries) and design affordances/heuristics (evolving technology affordances)

    9. Tension 5: Positive and Negative Consequences ofTemporary ConvergenceThe classic models of knowledge collaboration in groupsgive particular weight to the need for convergence. Con-vergence around a single goal, direction, criterion, pro-cess, or solution helps counterbalance the forces ofdivergence, allowing diverse ideas to be framed, ana-lyzed, and coalesced into a single solution (Couger 1996,Isaksen and Treffinger 1985, Osborn 1953, Woodmanet al. 1993). In fluid OCs, convergence is still likelyto exist during knowledge collaboration, but the conver-gence is likely to be temporary and incomplete, oftenimplicit, and is situated among subsets of actors in thecommunity rather than the entire community.

      Positive consequences: The temporary nature can advance creative uses of the knowledge without hewing to structures, norms or histories of online collaboration.

      Negative consequences: Lack of P2P feedback may lead to withdrawal from the group. Pace of knowledge building can be slow and frustrating due to temporary, fleeting convergence dynamics of the group.

    10. ension 2: Positive and Negative Consequencesof TimeA second tension is between the positive and negativeconsequences of the time that people spend contribut-ing to the OC. Knowledge collaboration requires thatindividuals spend time contributing to the OC’s virtualworkspace (Fleming and Waguespack 2007, Lakhani andvon Hippel 2003, Rafaeli and Ariel 2008). Time has apositive consequence for knowledge collaboration. Themore time people spend evolving others’ contributedideas and responding to others’ comments on thoseideas, the more the ideas can evolve

      Positive consequences: Attention helps to advance the reuse/remix/recombination of knowledge

      Negative consequences: "Old-timers" crowd out newcomers

      Tension can lead to "unpredictable fluctuations in the collaborative process" such as labor shortages, lack of fresh ideas, in-balance between positive/negative consequences that catalyzes healthy fluidity

      Need to consider other possibilities for time/temporal consequences. These examples seem lacking.

    11. We argue that it is the fluidity, the tensions that flu-idity creates, and the dynamics in how the OC respondsto these tensions that make knowledge collaboration inOCs fundamentally different from knowledge collabora-tion in teams or other traditional organization structures.

      Faraj et al identify 5 tensions that have received little attention in the literature (doesn't mean these are the only tensions):

      passion, time, socially ambiguous identities, social disembodiment of ideas, and temporary convergence.

    12. As fluctuations in resource endowments arise overtime because of the fluidity in the OC, these fluctua-tions in resources create fluctuations in tensions, makingsimple structural tactics for managing tensions such ascross-functional teams or divergent opinions (Sheremata2000) inadequate for fostering knowledge collaboration.As complex as these tension fluctuations are for the com-munity, it is precisely these tensions that provide thecatalyst for knowledge collaboration. Communities thatthen respond to these tensions generatively (rather thanin restrictive ways) will be able to realize this potential.Thus, it is not the simple presence of resources that fos-ter knowledge collaboration, but rather the presence ofongoing dynamic tensions within the OC that spur thecollaboration. We describe these tensions in the follow-ing section

      Tension as a catalyst for knowledge work/collaboration

    13. Fluidity requires us to look at the dynamics—i.e., thecontinuous and rapid changes in resources—rather thanthe presence or the structural form of the resources.Resources may flow from outside the OC (e.g., pas-sion) or be internally generated (e.g., convergence), sub-sequently influencing and influenced by action (Feldman2004). Resources come with the baggage of having bothpositive and negative consequences for knowledge col-laboration, creating a tension within the community inhow to manage the positive and negative consequencesin a manner similar to the one faced by ambidextrousorganizations (O’Reilly and Tushman 2004).

      Fluidity vs material resources

    14. However, failure to examine the critical roleof even the inactive participants in the functioning of thecommunity is to ignore that passive (and invisible) par-ticipation may be a step toward greater participation, aswhen individuals use passivity as a way to learn aboutthe collective in a form of peripheral legitimate partici-pation (Lave and Wenger 1991, Yeow et al. 2006).

      Evokes LPP

    15. Fluidity recognizes the highly flexible or permeableboundaries of OCs, where it is hard to figure out whois in the community and who is outside (Preece et al.2004) at any point in time, let alone over time. Theyare adaptive in that they change as the attention, actions,and interests of the collective of participants change overtime. Many individuals in an OC are at various stagesof exit and entry that change fluidly over time.

      Evokes boundary objects and boundary infrastructures.

    16. We argue that fluid-ity is a fundamental characteristic of OCs that makesknowledge collaboration in such settings possible. Assimply depicted in Figure 1, we envision OCs as fluidorganizational objects that are simultaneously morphingand yet retaining a recognizable shape (de Laet and Mol2000, Law 2002, Mol and Law 1994).

      Definition of fluidity: "Fluid OCs are ones where boundaries, norms, participants, artifacts, interactions, and foci continually change over time..."

      Faraj et al argue that OCs extend the definition of fluid objects in the existing literature.

    17. a growing consensus on factors that moti-vate people to make contributions to these communities,including motivational factors based on self-interest (e.g.,Lakhani and von Hippel 2003, Lerner and Tirole 2002,von Hippel and von Krogh 2003), identity (Bagozzi andDholakia 2006, Blanchard and Markus 2004, Ma andAgarwal 2007, Ren et al. 2007, Stewart and Gosain2006), social capital (Nambisan and Baron 2010; Waskoand Faraj 2000, 2005; Wasko et al. 2009), and socialexchange (Faraj and Johnson 2011).

      Motivations include: self-interest, identity, social capital, and social exchange, per org studies researchers.

      Strange that Benkler, Kittur, Kraut and others' work is not cited here.

    18. For instance, knowledge collaboration in OCscan occur without the structural mechanisms tradition-ally associated with knowledge collaboration in orga-nizational teams: stable membership, convergence afterdivergence, repeated people-to-people interactions, goal-sharing, and feelings of interdependence among groupmembers (Boland et al. 1994, Carlile 2002, Dougherty1992, Schrage 1995, Tsoukas 2009).

      Differences between offline and online knowledge work

      Online communities operate with fewer constraints from "social conventions, ownership, and hierarchies." Further, the ability to remix/reuse/recombine information into new, innovative forms of knowledge are easier to generate through collaborative technologies and ICT.

    19. Knowledge collaboration is defined broadly as thesharing, transfer, accumulation, transformation, andcocreation of knowledge. In an OC, knowledge collab-oration involves individual acts of offering knowledgeto others as well as adding to, recombining, modify-ing, and integrating knowledge that others have con-tributed. Knowledge collaboration is a critical elementof the sustainability of OCs as individuals share andcombine their knowledge in ways that benefit them per-sonally, while contributing to the community’s greaterworth (Blanchard and Markus 2004, Jeppesen andFredericksen 2006, Murray and O’Mahoney 2007, vonHippel and von Krogh 2006, Wasko and Faraj 2000).

      Definition of knowledge work

    20. Online communities (OCs) are open collectives of dis-persed individuals with members who are not necessarilyknown or identifiable and who share common inter-ests, and these communities attend to both their indi-vidual and their collective welfare (Sproull and Arriaga2007).

      Definition of online communities

    1. The situated and emergent nature of coordinationdoes not imply that practices are completely uniqueand novel. On the one hand, they vary accordingto the logic of the situation and the actors present.On the other hand, as seen in our categorizationof dialogic coordination, they follow a recognizablelogic and are only partially improvised. This tensionbetween familiarity and uniqueness of response is atthe core of a practice view of work (Orlikowski 2002).

      This is an important and relevant point for SBTF/DHN work. Each activation is situated and emergent but there are similarities -- even though the workflows tend to change for reasons unknown.

      Cites Orlikowski

    2. Recently, Brown and Duguid (2001, p. 208) sug-gested that coordination of organizational knowledgeis likely to be more challenging than coordination ofroutine work, principally because the “elements to becoordinated are not just individuals but communitiesand the practices they foster.” As we found in ourinvestigation of coordination at the boundary, signif-icant epistemic differences exist and must be recog-nized. As the dialogic practices enacted in responseto problematic trajectories show, the epistemic dif-ferences reflect different perspectives or prioritiesand cannot be bridged through better knowledge

      Need to think more about how subgroups in SBTF (Core Team/Coords, GIS, locals/diaspora, experienced vols, new vols, etc.) act as communities of practice. How does this influence sensemaking, epistemic decisions, synchronization, contention, negotiation around boundaries, etc.?

    3. nature point to the limitations of a structuralist viewof coordination. In the same way that an organi-zational routine may unfold differently each timebecause it cannot be fully specified (Feldman andPentland 2003), coordination will vary each time.Independent of embraced rules and programs, therewill always be an element of bricolage reflecting thenecessity of patching together working solutions withthe knowledge and resources at hand (Weick 1993).Actors and the generative schemes that propel theiractions under pressure make up an important com-ponent of coordination’s modus operandi (Bourdieu1990, Emirbayer and Mische 1998).

      Evokes the improvisation of synchronization efforts found in coordination of knowledge work in a pluritemporal setting

    4. These practices are highly situated, emer-gent, and contextualized and thus cannot be prespec-ified the way traditional coordination mechanismscan be. Thus, recent efforts based on an information-processing view to develop typologies of coordina-tion mechanisms (e.g., Malone et al. 1999) may be tooformal to allow organizations to mount an effectiveresponse to events characterized by urgency, novelty,surprise, and different interpretations.

      More design challenges

    5. Our findings also point to a broader divide in coor-dination research. Much of the power of traditionalcoordination models resides in their information-processing basis and their focus on the design issuessurrounding work unit differentiation and integra-tion. This design-centric view with its emphasis onrules,structures,andmodalitiesofcoordinationislessuseful for studying knowledge work.

      The high-tempo, non-routine, highly situated knowledge work of SBTF definitely falls into this category. Design systems/workarounds is challenging.

    6. Boundarywork requires the ability to see perspectives devel-oped by people immersed in a different commu-nity of knowing (Boland and Tenkasi 1995, Star andGriesemer 1989). Often, particular disciplinary focilead to differences in opinion regarding what stepsto take next in treating the patient.

      Differences in boundary work can lead to contentiousness.

    7. The termdialogic—as opposed to monologic—recognizes dif-ferences and emphasizes the existence of epistemicboundaries, different understandings of events, andthe existence of boundary objects (e.g., the diagnosisor the treatment plan). A dialogic approach to coordi-nation is the recognition that action, communication,and cognition are essentially relational and highlysituated. We use the concept of trajectory (Bourdieu1990, Strauss 1993) to recognize that treatment pro-gressions are not always linear or positive.

      Cites Star (boundary objects) and Strauss, Bourdieu (trajectory)

    8. A dialogic coordination practice differs from moregeneral expertise coordination processes in that itis highly situated in the specifics of the unfoldingevent, is urgent and high-staked, and occurs at theboundary between communities of practice. Becausecognition is distributed, responsibility is shared, andepistemic differences are present, interactions can becontentious and conflict laden.

      Differences between expertise and dialogic coordination processes.

    9. xpertisecoordination refers to processes that manage knowl-edge and skill interdependencies

    10. we describe two categories ofcoordination practices that ensure effective work out-comes. The first category, which we callexpertise coor-dination practices, represents processes that make itpossible to manage knowledge and skill interdepen-dencies. These processes bring about fast response,superior reconfiguration, efficient knowledge shar-ing, and expertise vetting. Second, because of therapidlyunfoldingtempooftreatmentandthestochas-tic nature of the treatment trajectory,dialogic coordina-tion practicesare used as contextually and temporallysituated responses to occasional trajectory deviation,errors, and general threats to the patient. These dia-logic coordination practices are crucial for ensuringeffective coordination but often require contentiousinteractions across communities of practice. Figure 1presents a coordination-focused model of patienttreatment and describes the circumstances underwhich dialogic coordination practices are called for.

    11. We found that coordination in a trauma settingentails two specific practices.

      "1. expertise coordination practices"

      "2. dialogic coordination practices"

      What would be the SBTF equivalent here?

    12. Based on a practice view, we suggest the followingdefinition ofcoordination: a temporally unfolding andcontextualized process of input regulation and inter-action articulation to realize a collective performance.

      Faraj and Xiao offer two important points: Context and trajectories "First, the definition emphasizes the temporal unfolding and contextually situated nature of work processes. It recognizes that coordinated actions are enacted within a specific context, among a specific set of actors, and following a history of previous actions and interactions that necessarily constrain future action."

      "Second, following Strauss (1993), we emphasize trajectories to describe sequences of actions toward a goal with an emphasis on contingencies and interactions among actors. Trajectories differ from routines in their emphasis on progression toward a goal and attention to deviation from that goal. Routines merely emphasize sequences of steps and, thus, are difficult to specify in work situations characterized by novelty, unpredictability, and ever-changing combinations of tasks, actors, and resources. Trajectories emphasize both the unfolding of action as well as the interactions that shape it. A trajectory-centric view of coordination recognizes the stochastic aspect of unfolding events and the possibility that combinations of inputs or interactions can lead to trajectories with dreadful outcomes—the Apollo 13 “Houston, we have a problem” scenario. In such moments, coordination is more about dealing with the “situation” than about formal organizational arrangements."

    13. Theprimarygoalispatientstabilizationandini-tiating atreatment trajectory—a temporally unfolding

      Full quote (page break)

      "The primary goal is patient stabilization and initiating a treatment trajectory—a temporally unfolding sequence of events, actions, and interactions—aimed at ensuring patient medical recovery"

      Knowledge trajectory is a good description of SBTF's work product/goal

    14. rauma centersare representative of organizational entities that arefaced with unpredictable environmental demands,complexsetsoftechnologies,highcoordinationloads,and the paradoxical need to achieve high reliabilitywhile maintaining efficient operations.

      Also a good description of digital humanitarian work

    15. We sug-gest that for environments where knowledge work isinterdisciplinary and highly contextualized, the rele-vant lens is one of practice. Practices emerge from anongoing stream of activities and are enacted throughthe contextualized actions of individuals (Orlikowski2000). These practices are driven by a practical logic,thatis,arecognitionofnoveltaskdemands,emergentsituations,andtheunpredictabilityofevolvingaction.Bourdieu (1990, p. 12) definespracticesas generativeformulas reflecting the modus operandi (manner ofworking) in contrast to the opus operatum (finishedwork).

      Definition and background on practice.

      Cites Bourdieu

    16. In knowledge work, several related factors sug-gest the need to reconceptualize coordination.

      Complex knowledge work coordination demands attention to how coordination is managed, as well as what (content) and when (temporality).

      "This distinction becomes increasingly important in complex knowledge work where there is less reliance on formal structure, interdependence is changing, and work is primarily performed in teams."

      Traditional theories of coordination are not entirely relevant to fast-response teams who are more flexible, less formally configured and use more improvised decision making mechanisms.

      These more flexible groups also are more multi-disciplinary communities of practice with different epistemic standards, work practices, and contexts.

      "Thus, because of differences in perspectives and interests, it becomes necessary to provide support for cross-boundary knowledge transformation (Carlile 2002)."

      Evokes boundary objects/boundary infrastructure issues.

    17. Usinga practice lens (Brown and Duguid 2001, Orlikowski2000), we suggest that in settings where work iscontextualized and nonroutine, traditional models ofcoordination are insufficient to explain coordinationas it occurs in practice. First, because expertise is dis-tributed and work highly contextualized, expertisecoordination is required to manage knowledge andskill interdependencies. Second, to avoid error andto ensure that the patient remains on a recoveringtrajectory, fast-response cross-boundary coordinationpractices are enacted. Because of the epistemic dis-tance between specialists organized in communitiesofpractice,theselattercoordinationpracticesmagnifyknowledge differences and are partly contentious.

      Faraj and Xiao contend that coordination practices of fast-response organizations differ from typical groups' structures, decision-making processes and cultures.

      1) Expertise is distributed 2) Coordination practices are cross-boundary 3) Knowledge differences are magnified

    18. In this paper, we focus on the collective perfor-manceaspectofcoordinationandemphasizethetem-poral unfolding and situated nature of coordinativeaction. We address how knowledge work is coor-dinated in organizations where decisions must bemade rapidly and where errors can be fatal.

      Summary of paper focus

    1. In other words, the articulation work [24], which had to be made explicit previously, became in part implicit by being embedded in the document and in the actions taken upon the document.

      Evokes Schmidt and Bannon's articulation work

    1. By ignoring the diversity and discord of the ‘goals’ of theparticipants involved, the differentiation of strategies, and the incongruence of theconceptual frames of reference within a cooperating ensemble, much of the currentCSCW research evades the problem of how to provide computer support for peoplecooperating through the establishment of a common information space.

      Has this design challege been adequately addressed in CSCW (and CHI, for that matter) in the last 30-ish years?

    2. On the one hand, the visibility requirement is amplified by this divergence. Thatis, knowledge of the identity of the originator and the situational context motivat-ing the production and dissemination of the information is required so as to enableany user of the information to interpret the likely motives of the originator. On theother hand, however, the visibility requirement is moderated by the divergence ofinterests and motives. A certain degree of opaqueness is required for discretionarydecision making to be conducted in an environment charged with colliding inter-ests. Hence,visibility must be bounded.

      What role does system meta data (version control, user history, etc.) play in bounding the visibility of decision making?

      This also seems to be an area ripe for more collaborative design approaches (participatory, reflective, feminist, etc.)

    3. Thus, a computer-basedsystem supporting cooperative work involving decision making should enhancethe ability of cooperating workers to interrelate their partial and parochial domainknowledge and facilitate the expression and communication of alternative perspec-tives on a given problem. This requires a representation of the problem domainas a whole as well as a representation, in some form, of the mappings betweenperspectives on that problem domain.

      This seems to still be a major challenge in information system design as well as collaborative workflow. Even if the information/meta context is made available, do people use it?

    4. If the decision making process (1) involves a large and indefinite number of peo-ple, (2) requires the integration of a number of different perspectives or domains,and (3) continues for a protracted period of time or even indefinitely, the interpreta-tion of the objects in a common database and hence the construction of a commoninformation space is hampered by the fact that the other originators and recipientsare not co-present.

      Ways to better integrate people engaged in distributed work are needed.

      Is this still true some 27 years later?

      Three particular information quality problems are raised by Schmidt and Bannon:

      1) provenance (originator) of the information and his/her/its reliability

      2) context of the information

      3) politics of the information

    5. The fact that information produced by discretionary decision making cannotbe conveyed anonymously has important implications for CSCW systems design.Naturally, such information must be accompanied by the identity of the source.But how to represent and present the identity of the source?

      This dilemma also applies to the complexity of representing time in information systems.

    6. In cooperative work settings involving discretionary decision making, the exer-cise of mutual critique of the decisions arrived at by colleagues is required for allparticipants. Therefore, in order to be able to assess information generated by dis-cretionary decision making, each participant must be able to access the identity ofthe originator of a given unit of information.

      Source credibility is a complex problem for SBTF. it is not always clear how/why a person on social media has certain information, how they interpret it, and how they summarize it.

    7. At the level of the objects themselves, shareabilitymay not be a problem, but in terms of their interpretation, the actors must attempt tojointly construct a common information space which goes beyond their individualpersonal information spaces. A nice example of how this is a problem has been givenby Savage (1987, p. 6): ‘each functional department has its own set of meaningsfor key terms. [...] Key terms such aspart, project, subassembly, toleranceareunderstood differently in different parts of the company.’

      This would be good to explore with SBTF in the interviews. Particularly, whether there are different meanings to time modes, time meta data, etc., applied by Core Team, Coordinators, GIS Team, experienced volunteers, new volunteers, etc.

      Is this part of the problem with articulating the information extracted from social media and entering it in the Google Sheet in order to become an artifact?

    8. Their importance lies in the interpretation human actors place on themeaning of the representational object. The distinction between the material carrierof information—the object—and its meaning is crucial. The material representationof information in the common space (e.g., a letter, memo, drawing, file) exists asan objective phenomenon and can be manipulated as an artifact. The semantics ofthe information carried by the artifact, however, is, put crudely, ‘in the mind’ of thebeholder, and the acquisition of information conveyed by the artifacts requires aninterpretive activity on the part of the recipient. Thus, a common information spaceencompasses the artifacts that are accessible to a cooperative ensembleas well asthe meaning attributed to these artifacts by the actors.

      Here Schmidt and Bannon describe the basis for articulation work in a common information space -- which encompasses interactions and breakdowns between information, metaphors, sensemaking, and artifacts.

      From a time mode perspective, this gets at what I describe as synchronization.

    9. Cooperative work is not facilitated simply by the provision of a shared database, butrequires the active construction by the participants of a common information spacewhere the meanings of the shared objects are debated and resolved, at least locallyand temporarily. Objects must thus be interpreted and assigned meaning, meaningsthat are achieved by specific actors on specific occasions of use. Computer supportfor this aspect of cooperative work raises a host of interesting and difficult issues.

      Pretty much a nutshell of the SBTF time study challenges.

    10. These protocols, formal structures, plans, procedures, and schemes can be con-ceived of asmechanismsin the sense that they (1) are objectified in some way(explicitly stated, represented in material form), and (2) are deterministic or at leastgive reasonably predictable results if applied properly. And they aremechanisms ofinteractionin the sense that they reduce the complexity of articulating cooperativework.

      People apply "mechanisms of interaction" to reduce the complexity of the articulation work.

      Schmidt and Bannon use these examples:

      • Formal and informal organizational structures • Planning and scheduling • Standard operating procedures (see Suchman's work on situated action) • Indexes and classifications for organizational and retrieval (see Bowker and Star on boundary objects/infrastructures)

    11. Therefore, instead of pursuing the elusive aim of devising organizational modelsthat are not limited abstractions and thus in principle brittle when confronted withthe inexhaustible multiplicity of reality, organizational models in CSCW applica-tions should be conceived of asresourcesfor competent and responsible workers.

      Schmidt and Bannon posit that organizational models in CSCW should be flexible enough to support new interpretations/evaluations of the model (contingent on circumstances), as well as capture decisions to "adapt, circumvent, execute, modify, etc. the underlying model".

    12. In this section of the paper we broach two aspects of this articulation issue, onefocusing on the management of workflow, the other on the construction and manage-ment of what we term a ‘common information space’. The former concept has beenthe subject of discussion for some time, in the guise of such terms as office automa-tion and more recently, workflow automation. The latter concept has, in our view,been somewhat neglected, despite its critical importance for the accomplishmentof many distributed work activities

      A quick scan of ACM library papers that tag "articulation work" seems to indicate the "common information space" problem still has not attracted a lot of study. This could be a good entry point for my work with CSCW because time cuts across both workflow and information space.

      Nicely bundles boundary infrastructure, sense-making and distributed work

    13. Articulation work

      Definition of articulation work: "Articulation work arises as a integral part of cooperative work as a set of activities required to manage the distributed nature of cooperative work. In the words of Strauss (1985, p. 8), articulation work is ‘a kind of supra-type of work in any division of labor, done by the various actors’:

    14. However, in general cooperative workin real world settings has a number of characteristics that must be taken into accountif CSCW systems are to be acceptable to users and, hence, commercially viable:

      Characteristics of cooperative work:

      (Taken verbatim from the paper)

      "Cooperative ensembles are either large, or they are embedded within larger ensembles."

      "Cooperative ensembles are often transient formations, emerging to handle a particular situation after which they dissolve again".

      "Membership of cooperative ensembles is not stable and often even non-determinable. Cooperative ensembles typically intersect."

      "The pattern of interaction in cooperative work changes dynamically with the requirements and constraints of the situation."

      "Cooperative work is distributed physically, in time and space."

      "Cooperative work is distributed logically, in terms of control, in the sense that agents are semi-autonomous in their partial work."

      "Cooperative work involves incommensurate perspectives (professions, specialties, work functions, responsibilities) as well as incongruent strategies and discordant motives."

      "There are no omniscient agents in cooperative work in natural settings."

    15. A cooperative work arrangement arises simply because there is no omniscientand omnipotent agent. Specifically, a cooperative work arrangement may emerge inresponse to different requirements (Schmidt,1990):

      cooperative work arrangements include:

      (verbatim from paper) • "augment the mechanical and information processing capacities of human individuals"

      "combine the specialized activities of multiple workers"

      • "application of multiple problem solving strategies and heuristics to a given problem"

      "application of multiple perspectives and conceptions on a given problem"

    16. The Rich Diversity of Cooperative Work

      Three many take-aways from cooperative work:

      1. It involves people doing work with specific characteristics, e.g., distributed, formed as ensembles, etc.

      2. Cooperative work occurs to produce a product or service together because of "technical necessities or economic requirements"

      3. is not limited by specific forms of interaction between workers

    17. As a research effort that involves a large number of established disciplines,research areas, and communities, CSCW is an arena of discordant views, incom-mensurate perspectives, and incompatible agendas. However, in the conception ofCSCW proposed here—as a research area devoted to exploring and meeting the sup-port requirements of cooperative work arrangements, CSCW is basically adesignoriented research area. This is the common ground. Enter, and you must change.

      Circa 1992 this description of CSCW as a design-oriented research area made sense to find some common ground between the CS groupware faction and the org studies, designers, social science, etc. Does this still hold up today?

    18. CSCW should be conceived of asan endeavor to understand the nature andrequirements of cooperative work with the objective of designing computer-basedtechnologies for cooperative work arrangements.

      Definition of CSCW (per Schmidt and Bannon). This is contested.

      Schmidt and Bannon argue later (pg 49) that "If CSCW is to be taken seriously, the basic approach of CSCW research should not be descriptive but constructive."

  5. Dec 2018
    1. which demands a genial age on the Southern hemisphere at the same time as an ice age on the Northern and vice versá

      Croll's work made important contributions to the understanding of Earth's climate. However, one problem with his theory was that it led to the conclusion that glacial periods occurred at different times in the Northern and Southern hemispheres.

      We now know this is not correct; ice ages are global. But at the time Arrhenius wrote this paper, the geological record of the ice ages was not understood well enough to rule out this possibility of separate glacial periods in the hemispheres.

    1. Marine reserves can clearly enhance exploited coral reef species that have relatively sedentary adult life-stages, in which some individuals live almost exclusively within reserve boundaries

      A study in 2 June 2009 conducted by Philip P. Molloy explored the relations with the age of the marine reserves and of the recovery of different species of fish. The studies showed that older marine reserves (15 years and older) were more effective than younger ones. They harbored more fish.

    1. hard work and exploration are valued over always knowing the right answer.

      The open program does this, to an extent. How can this be improved upon?

  6. Oct 2018
    1. It has been recognized for over 60 years that aerosol particles influence the earth's radiative balance directly by backscattering and absorption of shortwave (solar) radiation (1)
    1. more.

      The speaker regrets her past relationships and realizes they were so meaningless that she does not even remember them. She wishes she could have stayed with the one person she truly did love

  7. Sep 2018
    1. The result of this is easy to see: Those specifically requesting a lighter workload, who were disproportionately women, suffered in their performance reviews; those who took a lighter workload more discreetly didn’t suffer. The maxim of “ask forgiveness, not permission” seemed to apply.
    1. these systems were very slow, had a low assembly or operation yield, or were unable to exert appreciable forces against external loading.

      The authors recognize the significant achievement and potential of what others have done, but also note the ways in which the previous work can be improved. The goal of this paper is to build upon others' results and to develop new ideas to try to improve upon what has been done.

  8. Aug 2018
    1. "Protestant" life of wealth and risk over the "Catholic" path of poverty and security.[8]

      Is this simply a restatement of the idea that most of "the interesting things" happen at the border or edge of chaos? The Catholic ethic is firmly inside the stable arena while that of the Protestant ethic is pushing the boundaries.

    1. Then I noticed, each of the records in his queue had a set of codes in the Salutation field. He explained that there wasn't a way to see the current status from this view of their system. So, to avoid having to open each record, he used the Salutation field (which wasn't really used in the system) to store his own personal status codes.

      Work around for a design fail

    2. Once she finished, there was basically a cross-reference table of items that were actual business aspects and how they translated into the items required to use this system. In short, the last system that was delivered by the IT group required a change in the business process to use the application.

      In other words, the customer/user had to make changes (process, use of fields, etc) due to the defects of the design.

    1. Transformed in this process is the very nature of knowledge:Neoliberalization replaces education aimed at deepening and broadening intelligence and sensibilities, developing historical consciousness and her-meneutic adroitness, acquiring diverse knowledge and literacies, becom-ing theoretically capacious and politically and socially perspicacious, with [forms of] education aimed at honing technically-skilled entrepreneurial actors adept at gaming any system. (p. 123)

      neoliberalism and the transformation of knowledge and knowledge work

    1. The goal of this framework is to envision afuture of crowd work that cansupport more complex, creative, and highly valued work. At the highest level, a platformis needed for managing pools of tasksandworkers. Complex tasks must be decomposed into smaller subtasks, each designed with particular needs and characteristics which must be assignedto appropriate groups of workerswho themselves must be properly motivated, selected(e.g., through reputation), and organized (e.g., through hierarchy). Tasks may be structured through multi-stage workflowsin which workers may collaborateeither synchronously or asynchronously. As part of this, AImay guide (and be guided by) crowd workers. Finally, quality assuranceis needed to ensure each worker’s output is of high quality and fits together.

      Proposed framework to address crowdwork management challenges: shared resources, relationships, and crowd labor.

    2. n human computation, people act as computational components and perform the work that AI systemslack the skillstocomplete

      Human computation definition.

    3. A promising approach that addresses some worker output issues examines the way that workers do their work rather than the output itself, using machine learning and/or visualization to predict the quality of a worker’s output from their behavior [119,120]

      This process improvement idea has some interesting design implications for improving temporal qualities of SBTF data: • How is the volunteer thinking about time? • Where does temporality enter into the data collection workflow? • What metadata do they rely on? • What is their temporal sensemaking approach?

    4. Of the research foci, quality control has arguably received the most attention so far. Approaches for quality control largely fall into two camps: up-front task design and post-hoc result analysis. Task design aimsto design tasks that are resistant to low-quality work.

      Quality control processes is definitely a tension for SBTF.

      A better integrated task design and verification process at the end of activations could be more effectively address information quality concerns.

    5. Many tasks worth completing require cooperation –yet crowdsourcing has largely focused on independent work. Distributed teams have always facedchallenges in cultural differences and coordination[60], but crowd collaboration now must createrapport over much shorter timescales(e.g., one hour) and possibly wider culturalor socioeconomic gaps

      In Kittur's example, synchronous collaboration describes a temporal aspect (timescale and tempo of the work) related to how the collaboration is structured or not.

      "Short periods of intense crowd collaboration call for fast teambuilding and may require the automatic assignment of group members to maximize collective intelligence."

    6. Finally, it will be amajor research undertaking to invent and describe the tasks and techniques that succeed with synchronous collaboration

      Could this be a theme of the SBTF time study?

    7. The two core challenges for realtime crowdsourcing will be 1) scaling upto increased demand for realtime workers, and 2) making workers efficient enough to collectively generateresultsahead of time deadlines.

      One aspect of temporality in Kittur's study is related to "realtime" which they describe as the time need to scale up workers and efficiency speed of workers.

      The other temporal aspect is synchronicity of workers.

    8. Volunteer crowdsourcing platforms have evolved their own hierarchies and decision-making processes [104,156], appropriating techniques from other online communities where appropriate [101]. Most paid approaches have workers make hierarchical decisions collectively: for example, task decomposition and integration[75,80],quality oversight of each others’ contributions[78,100], and leader elections to represent collective opinions[83].

      Examples of hierarchical decision-making by both volunteer and paid crowd workers.

    9. Complex tasks have dependencies, changing requirements, and require multiple types of expertise.

      Characteristics of complex crowd work.

      Later, Kittur refers to complex crowd work as those involving "creativity, brainstorming, essay writing, music composition or civic planning."

      Temporality is definitely a work flow issue for SBTF.

      However, "realtime" is the only temporal attribute noted in this study but it seems to relate only to completion speed and present/immediacy of tasks.

    10. n the sections below, we survey and analyze the 12research focithat comprise our model. First, we consider the future of the work processesand how the workis organized and accomplished. Second, we consider the integration of crowd work and computation, including the symbiosis between human cognition, artificial intelligence(AI), and computationally-enabled crowd platforms. Finally, we consider crowd workers and how we can develop jobs, reputation systems, motivations, and incentives that will benefit them.

      Research foci

      Crowd work processes: Workflow, task assignment, hierarchy, realtime crowd work, synchronous collaboration. quality control

      Crowd computation: Crowds guiding AI, AIs guiding crowds, crowdsourcing platforms

      Crowd worker future: Job design, reputation/credentials, motivation/rewards

    11. Unlike traditional organizations in which workers possess job security and managers can closely supervise and appropriately reward or sanction workers, or distributed computing systems in which processors are usually highly reliable, crowd work poses uniquechallenges for both workers and requestersranging fromjob satisfactiontodirection-setting, coordination, and quality control.

      In the literature, quality tends to be used as an attribute of the output (content, HIT, etc.) but could/should it also refer to the crowd worker experience, as Kittur notes: "job satisfaction, direction-setting, coordination, and quality control"?

      How are these factors incorporated into the process and incentive system?

    12. These same requirements exist in distributed computing, in which tasks need to be scheduled so that they can be completed in the correct sequence and in a timely manner, with data being transferred between computing elements appropriately.

      time factors in crowd work include speed, scheduling, and sequencing

    13. However, crowd work can bea double-edged sword,equally capable of enhancing or diminishing the quality of workers’ lives.We maysee echoes of past labor abuses in globally distributed crowd work: extremely low pay for labor,with marketplaces such as Amazon’s Mechanical

      Crowd work offers flexibility to both workers and requesters to overcome labor shortages, need for expertise, and geographic boundaries.

      However, they are very real concerns about exploitation, piecemeal wages, unethical/dubious work, emphasis on speed over quality, and dehumanizing work conditions.

    14. We focus this paper on paid,onlinecrowd work, which we define here as the performance of tasks online by distributed crowd workers who are financially compensated by requesters(individuals, groups, or organizations). In this sense, crowd work is a socio-technical work systemconstituted through a set of relationships that connect organizations, individuals, technologies and work activities

      Kittur's definition of crowd work:

      "...performance of online tasks by crowd workers who are financially compensated by requesters."

    1. Other foundational accounts, like Moglen (1999) and Weber (2004),attended to the emergence of informal hierarchies and governance arrange-ments within communities.

      Other early work focused on organizational attributes, like how information goods were produced with flat/informal hierarchies, community values/norms, and governance structures.

    2. Peer productioncould, Benkler argued, outperform traditional organizational forms underconditions of widespread access to networked communications technologies,a multitude of motivations driving contributions, and non-rival informationcapable of being broken down into granular, modular, and easy-to-integrate

      Benkler's early work studied "the role of non-exclusive property regimes and more permeable organizational boundaries" for knowledge products.

  9. Jul 2018
    1. While some of this research has been aimed at building technologies to better support multi-tasking, other research has been critical, pointing out the negative consequences of distraction and task-switching [29]. A parallel line of thinking, called ‘presence bleed’ [16], articulates the way that multi-tasking and extended temporal boundaries blur individuals’ professional and personal identities as work bleeds into and throughout multiple spheres

      Maladapative/problematic studies of time include: multitasking, time-switching, presence bleed (work-life convergence), morality, agency and power, individual vs organizational choices, 24/7 availability, etc.

    2. CSCW has been investigating the relationship of time and work practically from its inception as a scholarly fiel

      Classic CSWC literature on time includes: groupware calendaring systems, temporal rhythm, temporal trajectories, temporal ordering, temporal artifacts.

  10. course-computational-literary-analysis.netlify.com course-computational-literary-analysis.netlify.com
    1. beyond any reasonable doubt

      With this key phrase of legal discourse, Cuff's takes on the role of a prosecutor in a courtroom, shouldering the burden of proof in the case at hand. What is the relationship between detective work and legal argumentation? How does the novel's language put various characters on trial, not only before other characters, but also before the novel's jury of readers? A word collocation analysis of words and phrases with legal significance would help us to determine whether or not legal language shapes standards of evidence in The Moonstone.

    2. Here, again, there is a motive under the surface; and, here again, I fancy that I can find it out.

      Once again, we encounter the language of detective work, which often involves the uncovering and probing of underlying motives. What distinguishes Betteredge's "detective fever" from Ezra Jennings's understanding of detection? We could operationalize this comparative question into a word collocation study of target words that are associated with detective work (e.g., "detective," "suspect," "motive," etc.).

    1. Lev Vygotsky’s seminal work asserted that social interaction is a fundamental aspect of learning. And if he were alive today, he would most likely agree with the saying “two minds are better than one.” He might add, “Better yet, how about three or four?”

      Vygotsky- social interaction is fundamental in learning- group work is the perfect way to do this- 2 heads are better than one:)

    1. Attitudes towards looking like you’re working when you aren’t are akin to school policies that require students to perform attention, as though the performance of attention may be linked to actual attention, or even learning. The pretending takes precedence over the actual doing.

      Amazing parallel here.

  11. Jun 2018
    1. But what makes the story in places like Toledo and the region around it hard for many politicians and even economists to understand is that the anxiety goes well beyond automation and the number of jobs. For many people, your job defines your life.
    2. I had a learning disability when I was in school. But I could do factory work. Factory work is what we did. Now robots do that job. What happens to people like me?
    3. People have come to believe that they, their jobs, their communities, and the social contract that binds them to work and place and each other are under threat. And they’re not wrong.

      I have a lot of criticisms of the self-occupation link. But this is really interesting connecting self-occupation-community-social contract.

    1. white-tailed deer (Odocoileus virginianus) have persisted in the absence of predators for more than a century, causing the successive elimination of saplings of less and less palatable trees and shrubs

      In this study, it was discovered that balsam fir, the island's original dominant tree species, was not able to recruit as it was a favorite food for deer. White spruce, and several companion species, have replaced the fir as deer do not find them palatable.

    2. mesopredator release [coyotes (Canis latrans) maintaining small vertebrate species in chaparral habitats

      It was observed that the loss of coyotes as an apex predator control on smaller vertebrate predators, along with habitat fragmentation, led to trophic cascades in the ecosystem.

    3. predatory seastars in the rocky intertidal

      Predatory sea stars regularly graze the rocky intertidal and are not prey-specific. Their grazing opens new substrate for multiple species, preventing the dominant species from colonizing all of the rocks.

    4. Other examples include the spread of the invasive brown tree snake (Boiga irregularis) on the otherwise vertebrate predator–free island of Guam

      A number of different factors led to the success of the brown tree snake in Guam: barrier-free dispersal, few safe areas for avian prey, lifestyle of the predator (nocturnal and arboreal), and ability of predator to find prey under varying conditions.

    5. In contrast, introduced rats (46) and arctic foxes (Fig. 4) (47) have reduced soil fertility and plant nutrition on high-latitude islands by disrupting seabirds and their sea-to-land nutrient subsidies, with striking effects on plant community composition.

      A metastudy of 45 replicated and 35 unreplicated field experiments found that introduced predators had double the negative effect than native predators on their vertebrate prey:

      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1950296/

    6. For example, the reintroduction of wolves to Yellowstone National Park has reduced the positive indirect effects of ungulates on soil nitrogen mineralization and potentially the nitrogen supply for plant growth

      Researchers found that after wolves were reintroduced to Yellowstone, there was a net decline in soil nitrogen, likely due to fewer large herbivores. In addition, the spatial nature of nitrogen renewal changed due to new use patterns by the herbivores.

    7. From land, the demise of Pleistocene megaherbivores may have contributed to or even largely accounted for the reduced atmospheric methane concentration and the resulting abrupt 9°C temperature decline that defines the Younger-Dryas period

      Herbivores produce large amounts of methane, a potent greenhouse gas, as a by-product of their diet. By losing so many of these organisms during the Pleistocene and early Holocene, the methane concentration in the atmosphere would have dropped rapidly, helping to cause the global cooling of the Younger-Dryas.

    8. In freshwater systems, the localized rise and fall of human malaria is associated with the impacts of predatory fishes on planktivores, which are in turn important consumers of mosquito larvae

      In this case, researchers found that certain types of predatory fish, while consumers of mosquito larvae, also regularly consumed the mosquito's main predators, leading to increased malaria infections.

    9. Further examples of the interplay between predation and disease exist for aquatic systems. The establishment of no-take marine reserves in the Channel Islands of southern California led to increases in the size and abundance of spiny lobsters (Panulirus interruptus) and declines in population densities of sea urchins, which are preyed on by the lobsters. The reduced urchin densities thwarted the spread of disease among individual sea urchins, which led to a lowered frequency of epidemics of sea urchin wasting disease within the reserves

      By allowing the expansion of the predator population (spiny lobster), the prey population size (sea urchins) were held in check and individual urchins suffered from disease less often.

    10. A similar result, involving different species and processes, occurred in India, where the decline of vultures also led to increased health risks from rabies and anthrax

      Because of overuse of antibiotics in livestock, the vulture population declined, leading to more scavenging by feral dogs of carcasses throughout the region. As the dog populations grew, and due to their proximity to humans, the risk of transmission of rabies to humans has increased greatly.

    11. For example, the reduction of lions and leopards from parts of sub-Saharan Africa has led to population outbreaks and changes in behavior of olive baboons

      In this case, the apex predators have been overhunted by humans for bushmeat, for trophies, or as pests to their livestock.

    12. Although the extent and quality of evidence differs among species and systems, top-down effects over spatial scales that are amenable to experimentation have proven robust to alternative explanations

      In a metastudy of 41 papers and 60 independent tests, it was found that terrestrial trophic cascades occurred with more frequently than previously thought across systems and were on par with aquatic environments. While the strength of the cascade response varied across systems based on several factors (type of carnivore, plant antiherbivore defenses, type of damage measured, etc.), trophic cascades were common, although not universal.

    13. The omnipresence of top-down control in ecosystems is not widely appreciated because several of its key components are difficult to observe.

      To see the effects of one such natural experiment, read: http://science.sciencemag.org/content/294/5548/1923

    14. The history of life on Earth is punctuated by several mass extinction events (2), during which global biological diversity was sharply reduced. These events were followed by novel changes in the evolution of surviving species and the structure and function of their ecosystems. Our planet is presently in the early to middle stages of a sixth mass extinction (3), which, like those before it, will separate evolutionary winners from losers.

      There have been 5 mass extinctions on Earth in the past. These were caused by various natural events, from gamma-ray bursts to megavolcanic eruptions to meteor strikes. During each mass extinction, species diversity diminished significantly in a short period of time. Each mass extinction was followed by the evolution of novel forms of organisms that transformed their habitats in new ways.

      Most scientists agree that we are currently in the 6th mass extinction event, this one largely caused by human activities such as climate change, habitat loss/fragmentation, pollution, invasive species, and human consumption/overexploitation.

    15. For example, empirical research in Serengeti, Tanzania, showed that the presence or absence of apex predators had little short-term effect on resident megaherbivores [elephant (Loxodonta africana), hippopotamus (Hippopotamus amphibius), and rhinoceros (Diceros bicornis)] because these herbivores were virtually invulnerable to predation (24). Conversely, predation accounted for nearly all mortality in smaller herbivores [oribi (Ourebia ourebi), Thompson’s gazelle (Eudorcas thomsonii), and impala (Aepyceros melampus)], and these species showed dramatic increases in abundance and distribution after the local extinction of predators.

      In this study, it was noted that ungulates above 150 kg were regularly limited by food availability instead of predation, due to their large body sizes.

      Conversely, small ungulates (<150 kg) were regular prey items of the several large carnivores on the Serengeti and their populations, and the trophic levels below them, were controlled by the apex predators.

      Loss of predators in these systems caused much greater impacts on the smaller herbivores than the larger ones.

    1. (Childers, 2006; Hao et al., 2011; Schedlbauer et al., 2012)

      Childers and colleagues demonstrated that Everglades hydrology was co-varying with changes in greenhouse warming potentials, energy fluxes and C dynamics which proved that hydrology is important for creating and maintaining conditions sufficient for wetland ecosystem and structure

    2. (Jimenez et al., 2012)

      Jimenez and colleagues studied the effects of carbon balance in wetland ecosystems before the planned Everglades restoration of historical water flow. They trajected that there would be an alteration on the carbon dynamics of the Everglades as a whole.

    3. (Dugan, 1993)

      Dugan examined wetlands in the United States and the total loss of thus ecosystem. This atlas was able to divide the world’s regions into 19 sections and develop information on the wetlands.

  12. May 2018
    1. This empirical work supports long-standing theory about the role of top-down forcing in ecosystems but also highlights the unanticipated impacts of trophic cascades on processes as diverse as the dynamics of disease, wildfire, carbon sequestration, invasive species, and biogeochemical cycles.
    2. The loss of these animals may be humankind’s most pervasive influence on nature

      There are a number of different impacts of humans on the biosphere but loss of apex predators is thought to be one of the widest ranging issues of the planet.

      An overview of the threats to the planet's largest 31 carnivores an implications can be found here: http://science.sciencemag.org/content/343/6167/1241484

    1. prosum-ers

      A person who influences the purchase of a product; they don't only consume it, they convince others to buy it by consuming it themselves. e.g. a you-tuber who is sent clothing, wears that clothing in a video, and then links it in their video as a product for purchase and gets money for it.

  13. Dec 2017
    1. Low values indicate that transisthmian pairs showed little tolerant behavior or much intolerant behavior relative to intraoceanic pairs of the same taxa.

      Schein, H. (1975). Aspects of the aggressive and sexual behaviour of alpheus heterochaelis say. Marine Behaviour and Physiology, 3(2), 83–96. https://doi.org/10.1080/10236247509378498

      This previous work studies aggressive and sexual behavior in snapping shrimp. Although the snapping shrimps studied were found in North Carolina, their behavior reflects the behavior of the genus. Here they established that males seek females using chemical cues, and in general a male with a larger claw/larger body size favors larger females that can produce more offspring. Also, males with larger claws are stronger and can out compete smaller males. In relation to this publication, this previous work establishes a background of the behavior of the snapping shrimp. Understanding their natural behavior helps in understanding how the authors of this publication reached their conclusion. (JP)

    2. sibling species

      Knowlton, N. (1986). Cryptic and Sibling Species among the Decapod Crustacea. Journal of Crustacean Biology, 6(3), 356-363. doi:10.2307/1548175

      This previous work defines the term sibling species. According to Knowlton, sibling species are species that have been shown to be very closely related using biochemical techniques such as electrophoretic analysis. Sibling species are not the same species. This publication also uses electrophoretic analyses, known as starch gel electrophoresis, to differentiate between species of snapping shrimp. (JP)

    3. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Knowlton, Nancy & Mills, DeEtta. (1992). The Systematic Importance of Color and Color Pattern: Evidence for Complexes of Sibling Species of Snapping Shrimp (Caridea: Alpheidae: AZ'heus) from the Caribbean and Pacific Coasts of Panama. Proceedings of the San Diego Society of Natural History. 18.

      This past publication explains how loosely related, or distantly related, species in the genus Afpheus Fabricius (snapping shrimp) can be distinguished based on color morphology such as differences in color patterns. This relates with this publication because both are related to the speciation of snapping shrimp in the Isthmus of Panama. Both publications find methods to differentiate between species; while this paper uses mtDNA and allozymes to compare genetic distance, the other paper uses careful analyses of color patterns to separate species. (JP)

    4. snapping shrimp genus Alpheus

      Sexual selection and dimorphism in two demes of a symbiotic, pair-bonding snapping shrimp Knowlton, N. (1980), SEXUAL SELECTION AND DIMORPHISM IN TWO DEMES OF A SYMBIOTIC, PAIR-BONDING SNAPPING SHRIMP. Evolution, 34: 161–173. doi:10.1111/j.1558-5646.1980.tb04802.x

      This previous work provides evidence on how differences between mates affects mate choice and, with environmental constraints, can lead to sexual dimorphism which is a distinct difference in size or appearance between the sexes of the same species. This study found that snapping shrimp are very aggressive and territorial to other shrimps of the same sex. By having these type of aggressive traits, compatibility would decrease as species are more separated. This supports one of the results found in this publication. (JP)

    5. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Svitil, K.A. (1993). "Oceans Divided". Discover, pp.1-2.

      A magazine article by Kathy Svitil talks about the closure of the Isthmus of Panama. She talked about how the rise of Panama 3.5 million years ago separated Atlantic and Pacific species before the land-bridge could even form. This was caused by the shift in tetonic plates, where the Pacific Ocean floor shifted underneath the Carribean plate before melting/solidifying by lava. She states how animals felt the influence of the rifts coming together, even quoting Nancy Knowlton on the speciation of snapping shrimps on either sides of Isthmus since these shrimps used to live in deeper depths of the ocean.

      ~(J.D.A.)

    6. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Knowlton, N. & Keller, B.D. (1982). "Symmetric Fights as a Measure of Escalation Potential in a Symbiotic, Territorial Snapping Shrimp." Behavioral Ecology And Sociobiology, 10(4): 289-292.

      This journal goes into detail the behavioral aspect of the Alpheus shrimp. This species readily defends its territory using its large snapping claw. Results gathered focused on symmetric fights of shrimps in regards to sex, size, and resources. According to this study, larger females are more likely to defend their anemone territories and showed more aggressiveness than the male shrimps. The losers of these contests experienced severe injuries by these large females than any other type of shrimps.

      ~(J.D.A.)

    7. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Glynn, P.W. (1985). “El Nino-Associated disturbance to coral reefs and post disturbance mortality by Acanthaster planci.” Marine Ecology Progress Series, 26(17): pp. 295–300.

      Another study shows how in 1985 the coral reefs in eastern Pacific (Panama included) got ruined by El Nino due to very high water temperatures (average of 31 Celsius) and depth penetration (over 100 m). Since most habitats in coral reefs were destroyed, many species were easily exposed to predators. This may affect the results obtained by Mills and co. because barely a decade has passed for the marine habitats in Panama to recuperate.

      ~(J.D.A.)

    8. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Read, A., McTeague, J., & Govind, C. (1991). "Morphology and behavior of an unusually flexible thoracic limb in the snapping shrimp, Alpheus heterochelis". The Biological Bulletin, 181(1): pp. 158-168.

      This journal explains the morphology of the snapping shrimp Alpheus. Their second thoracic limb is thinner, flexible, bilaterally symmetrical, and possess larger ganglion. This type of limb is almost always active in regards to grooming and foraging for food. The major cheliped, or the larger claw, is used to produce loud popping noises as a defense mechanism against predators.

      ~(J.D.A.)

    9. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Bermingham, E. & Lessios, H.A. (1993). “Rate Variation of Protein and Mitochondrial DNA Evolution as Revealed by Sea Urchins Separated by the Isthmus of Panama.” Proceedings of the National Academy of Sciences, 90(7): pp. 2734–2738.

      Another research was made in regards to the closure of Isthmus of Panama 3 MA based on changes in oxygen/carbon ratios in sea water. The main subject studied was sea urchins. Bermingham and Lessios compared mtDNA and protein divergence among three differ species of sea urchins--Diadema, Echinometra, & Eucidaris. Results concluded that protein divergence between Atlantic and Pacific sea urchin species only differed by 1 order of magnitude, so no significant difference. The Diadema species had an overlap of allele frequencies whereas the other two species displayed fixed loci for differ alleles of both shores, which may hint towards gradual genetic drift or mutations.This proves that other marine life besides the Alpheus shrimp community were also affected by a change in the environment via closure of Panama Isthmus.

      ~(J.D.A.)

    1. promote neuronal dysfunction (12).

      Amyloid beta accumulation creates synaptic impairment and learning and memory deficits in AD patients. The impairment of neurons as opposed to neuronal loss maybe the mechanism behind cognitive impairment in AD patients. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385944/)

    2. Hippocampal theta and gamma oscillations and cross-frequency coupling (CFC) through theta-phase modulation of gamma power are measures of network activity related to memory, including in humans

      Phase amplitude coupling measures the coupling between theta and gamma waves in the hippocampus. The theta and gamma waves are associated with learning and memory. Figure I shows virtually no phase amplitude frequency in the mice with Alz compared to Alz free mice, especially in the APP23p38𝛾-/- mice. Such low frequencies would suggest those mice would have the most problems with learning and memory.

      http://www.physiology.org/doi/abs/10.1152/jn.00106.2010

    3. PSD-95/tau/Fyn

      Researchers have found the binding of tau and fyn have been associated with Alzheimer’s disease pathology. Fyn is a kinase that phosphorylates tau and co-localizes with tau in the neurons of Alzheimer’s patients with tau tangles. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4870772/

    4. Aβ is thought to trigger toxic events, including tau phosphorylation

      E. S. Musiek, D. M. Holtzman, Nat. Neurosci. 18, 800–806 (2015). Amyloid-beta is a key initiator of all the downstream processes that cause Alzheimer’s. One process Aβ leads to is initiating tau tangles. Even though Aβ is a key player, Aβ can not cause Alzheimer’s by itself.

    5. Aberrant tau phosphorylation is the first step in a cascade leading to its deposition and to cognitive dysfunction

      K. Iqbal, F. Liu, C.-X. Gong, A del C. Alonso, I. Grundke-Iqbal, Acta Neuropathol. 118, 53–69 (2009). Neurodegeneration from tau implications can be caused from different protein kinases hyperphosphorylating tau. Hyperphosphorylated tau can misfold, create tangles, and not able to stabilize microtubules, all which can all lead to loss of connectivity between neurons.

    6. APP23 mice present with premature mortality, memory deficits, neuronal circuit aberrations with epileptiform brain activity, and Aβ pathology

      L. M. Ittner et al., Cell 142, 387–397 (2010)

      APP23 mice have increased Aβ toxicity which is the main contributor to the deficits seen in APP23 mice. Deficits include premature death, increased Aβ at young ages, decreased memory, and irregular neuronal circuits.

    7. N-methyl-D-aspartate (NMDA)–type glutamatergic receptors (NRs) drive glutamate-induced neuronal excitotoxicity

      Hardingham and Bading show that NMDAR responses depend on receptor location. Synaptic NMDARs promotes cell survival, while stimulation of extrasynaptic NMDARs promotes cell death. The unequal stimulation of these receptors cause neuronal dysfunction, while stimulation of synaptic receptors could be used a protective therapy.

    8. However, this finding is in line with the idea that tau is involved in normal physiologic NR signaling events in neurons (12).

      In normal physiological conditions tau is used to stabilize microtubular cytoplasmic components in neurons.

    9. APP23

      APP23 is a version of APP that will develop into AB plaques and aggregates that are associated with Alzheimer’s disease. The APP23 mouse in the experiment overexpressed the APP23 protein.

      Previous work: Animals can produce amyloid-beta independently of using APP precursor protein. However, when animals have APP23 mutation, the APP is overexpressed and amyloid beta plaques and intracellular amyloid beta aggregates form. The APP23 has been linked to synapse loss and dendrite degeneration. The APP23 is a Swedish mutation in CNS neurons. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4046770/ )

    10. This is contrary to the current view that tau phosphorylation downstream of Aβ toxicity is a pathological response (3).

      Ittner and Gӧtz review new findings showing the interactions of tau and amyloid beta. Tau can shift from the axon to the dendrite helping to increase amyloid beta toxicity.

    11. We have previously shown that postsynaptic PSD-95/tau/Fyn complexes mediate Aβ-induced excitotoxicity

      L. M. Ittner et al., Cell 142, 387–397 (2010).: In this article, Ittner and others show that the absence of tau in amyloid beta-forming mice lessens the severity of amyloid beta toxicity. These results suggest that tau and amyloid beta together increases the symptoms and progression of Alzheimer’s disease.

    1. lower incidence of reduced birth weight, and reduced

      Beall, C. M. (2007). Two routes to functional adaptation: Tibetan and Andean high-altitude natives. Proceedings of the National Academy of Sciences, 104(Supplement 1), 8655-8660. doi:10.1073/pnas.0701985104

      These are some of the physiological traits that were found to be different between populations of Tibetan highlanders and Han Chineese. These include but are not limited to: less oxygen in the arteries, higher breathing rate at rest, loss of low oxygen induced blood vessel constriction, and lower occurrences of decreased birth weight, as well as decreased hemoglobin concentrations.

    2. Because sex and age affect Hb concentration in Tibetans and Han Chinese, and the age effect differs between males and females

      This paper discusses the effect of gender on hemoglobin levels in Han Chinese and Tibetan Plateau inhabitants as a mechanism for high altitude adaptation. In Han populations a correlation was seen between increased altitude and increased hemoglobin levels (men having higher hemoglobin concentration than women), this correlation was not see in Tibetan highland inhabitants, or between genders of Tibetan highland individuals.

    1. Regression analyses describing the relationships between protein divergence estimates and divergence time estimates were implemented for each sex-determining protein as well as for SSX using the program

      It has been noted that protein divergence increases as divergence time increases, thus being said as time increases more protein divergence occurs. To learn more click here. http://www.pnas.org/content/94/24/13028.full.pdf

      • Jake Barbee
  14. Nov 2017
    1. S. F. Ober

      S.F. Oberbauer's previous work:

      National Science Foundation – Ecosystems. Causes and implications of dry season control of tropical wet forest tree growth at very high water levels: direct vs. indirect limitations (CARBONO - VERANO project).

      National Science Foundation – Polar Programs. Arctic Observing Networks: Collaborative Research: Sustaining and amplifying the ITEX AON through automation and increased interdisciplinarity of observations (AON-ITEX).

      NSF-Arctic Natural Sciences. Collaborative Research; cold-season gas exchange of arctic plants - resolving winter carbon and water balances of Alaskan arctic tundra (Coldseason project).

      NSF -IPY Arctic Observing Networks � Study of Arctic ecosystem changes in the IPY using the International Tundra Experiment. (ITEX-IPY)

      DOE-NICCR. Response of carbon dioxide, water, and energy exchange of peat and marl wetlands in the Florida Everglades to changes in hydroperiod (Evergladesflux).

      NSF-Biocomplexity. Biocomplexity Associated with the Response of Tundra Carbon Balance to Warming and Drying Across Multiple Scales. Barrowbiocomplexity (this project has sunsetted). Effects of increased season length on plant phenology, community composition, productivity, and ecosystem carbon fluxes in Alaskan tundra Season project (this project has sunsetted)

      Carbon stockes and fluxes in a tropical rain forest in Costa Rica Carbono project

      NSF- Integrated carbon program. Understanding interannual NEE variability in a tropical rain forest using constrained estimates of carbon exchange. S.F. Oberbauer, D.A. Clark, M. Ryan, D.B. Clark. Carbono-Towers

      National Science Foundation - Biocomplexity of the Environment Coupled Biogeochemical Cycles. Complex interactions among water, nutrients and carbon stocks and fluxes across a natural fertility gradient in tropical rain forest. (CICLOS PROJECT).

      RW

    1. (Talbert and Henikoff 2014; Santoro and Dulac 2015; Suárez-Ulloa et al. 2015).

      The way that organisms respond to their environment is ultimately through gene expression. For example, growth is caused by production of growth hormones, among other factors, which are turned on and off. Eukaryotic organisms use histone regulation as one way to respond to environmental changes. It has been found that exchange of histones can occur due to changes in temperature and season, during conflict, movement, learning, and more. AT

    2. (González-Romero et al. 2012)

      H2A.Z.1 is a well documented histone variant. It plays a role in keeping genome integrity, They are highly conserved, even more than H2A.X. AT

    3. (Gavery and Roberts 2010, 2012; Suárez-Ulloa et al. 2015).

      Recent research on mollusc DNA has found that they do use methylation systems to regulate their expression. This was determined by using bisulfate PCR. The bisulfate creates a tag on a methylated amino acid in the protein sequence, and PCR is a way to generate many different copies of a single strand of DNA. Using different mapping techniques the locations of methyl group were determined. A methyl group added to a DNA structure serves to wrap the DNA tighter around the histone in order to block transcription. AT

    4. (Talbert and Henikoff 2014).

      The histone variant H2A.Z Is the most important regarding environmental epigenetic responses. environmental epigenetic are everyday factors in an organism’s life that affect how their genes are expressed that does not create a change in their DNA. AM

    5. (Simonet et al. 2013) and at least 3 different H2A.Z variants in plants (Yi et al. 2006).

      H2A.Z was found to have four different subtypes in the Cyprinus carpio, due to the organisms high sense of acclimatization (an individual organisms ability to adjust to a change in its environment such a s a change in altitude, temperature, and humidity). The four subtype variants aid in the thermoregulation (process that allows the body to maintain a core internal temperature) and stability of the organism. KM

    6. Bönisch et al. 2012

      H2A.Z.2.2 is found in all human (and some primate species) cell lines but it is found mostly in the brain. It is achieved through alternative splicing of the H2AZ variant. Through biochemical fractionation, the paper results suggest that Z.2.2 causes major structural changes and significantly destabilizes nucleosomes. The findings add to the list of known variants of the H2A.Z family. EM

    7. (Dryhurst et al. 2009; Horikoshi et al. 2013; Nishibuchi et al. 2014).

      The papers research clear differences in the structure of the two H2A variants: one in amino acid 38 and one in the structures of the L1 loop. Through mutational analysis, the paper concluded that the amino acid difference at position 38 is partially responsible for the unique functional specializations of H2AZ.1 and H2AZ.2. EM

    8. (Eirín-López et al. 2009b)

      H2AZ has experienced multiple rounds of specialization which gave rise to new variants. Most vertebrates exhibit the H2AZ.1 and H2AZ.2 variants encoded by independent genes. While their protein products are similar, their promoter regions are very different, suggesting they are each tasked with different roles. The research utilized phylogenetic analysis of the promoter regions to conclude that they evolved separately during vertebrate evolution. EM

    9. (Matsuda et al. 2010), the differences in their mRNA expression levels in human tissues (Dryhurst et al. 2009), the presence of embryonic lethality in mice lacking H2A.Z.1 (Faast et al. 2001), and the specific role of H2A.Z.2 in metastatic melanomas (Vardabasso et al. 2015).

      They determined that the H2A.Z.1 and H2A.Z.2 are functionally different by individually turning them off and on by knocking out/deleting the gene that codes for the protein. By doing this they discovered that each gene codes for a different protein. Then they discovered that the knockout of each protein resulted in the loss of a distinct function. This work was done in several different studies using different types of cells, such as chicken and human. AT

    10. (Dryhurst and Ausió 2014).

      Highly dynamic chromatin state means that the chromatin is quickly unraveling and raveling to allow transcription, this happens because the histones are rapidly being exchanged from a core to a variant. The variants each give different functions and change the rate of transcription. AM

    11. (González-Romero et al. 2008; Eirín-López et al. 2009a)

      H2A.Z was derived from H2A through a series of mutations that resulted in it being 60% different from the core H2A. This was determined using a system called GWLA methodology which synthesizes two protein structure determining methods. It breaks the protein into fragments and then sequences it. The H2A.Z is highly conserved throughout eukaryotes meaning that the sequence is the same. Because there are few or no mutations this means that the function is very important and a mutation would be lethal. AT

    12. Among histones, the H2A family stands out because of the high number of specialized variants it displays (González-Romero et al. 2008), including some of the most studied histones so far such as H2A.X (involved in DNA repair; Li et al. 2005) and H2A.Z (essential for the survival of most eukaryotic organisms; Eirín-López and Ausió 2007; Talbert and Henikoff 2010).

      The family of H2A histone proteins are essential in understanding the biochemistry of chromatin-associated proteins in Mollusca. H2AZ is a variant form of the histone protein that regulates a mediated thermosensory response. The H2A.X variant form contributes to the formation of the nucleosome and its structural integrity.

      KM

    13. (Ausió 2006; Talbert and Henikoff 2010; Henikoff and Smith 2015)

      The papers discuss several structural studies on core histones and linker histone variants. The papers focused on the roles of nucleosome stability, with data showing that histone variability plays an important role in regulation of chromatin metabolism. EM

    14. (Luger et al. 1997; van Holde 1988)

      They determined the structure of histone proteins through crystallography which uses a computer modeling system to determine the atomic structure and how it assembles to form a superhelix model. KM

    1. However, this hypothesis has not been fully tested because the electrosensory input has not yet been well described during exploratory behaviors in freely moving fish.

      The author states that it's difficult to examine the exploratory behavior of a free moving fish because the data typically used does not accurately describe the fish's behavior. The EOD geometry and the electric images are complex because they can change based on the fish's movement. The movement changes the source of the electric organs and in laboratory setting the behavior that use electrorepection are hard to maintain preparations for . The difficulty experienced in a control laboratory setting to examine the certain behaviors, makes collecting and analyzing data of a free moving fish ,a challenge .

      • Michelle Oriana Gomez-Guevara
    1. basis underlying sex determination in this group

      In the Drosophila group, members of the Drosophila group have either one or two X chromosomes and two sets of autosomes. Sex determination is determined for females by having balanced female determinants on the X chromosome. For males of the Drosophila group sex determination is based on the determinants on the autosomes. If there is only one X chromosome present in a diploid cell the member of the Drosophila group is male, this is shown by the ratio of (1X:2A). To learn more click here https://www.ncbi.nlm.nih.gov/pubmed/18956315 -Jake Barbee

    1. . However, they do show some distributional differences that could affect sensitivity to changing conditions associated with gradual rise of the isthmus

      Heck, K. L. (1977). Comparative species richness, composition, and abundance of invertebrates in Caribbean seagrass (Thalassia testudinum) meadows (Panamá). Marine Biology, 41(4), 335–348. https://doi.org/10.1007/BF00389099

      This previous work compares the species composition and abundance of invertebrates in the Caribbean coast of Panama and the Panama Canal Zone. While discussing some factors that could have affected this experiment, the author of this publication noted that the Panama Canal zone could have led to the displacement and death of many snapping shrimp. This previous work observed that species composition of invertebrates (which include snapping shrimp) were the same in tropical and subtropical seagrass meadows, however, different species of shrimp had a lower total abundance. This could mean that the formation of the Isthmus of Panama, followed by the construction of the Panama Canal, had an effect on speciation of several species of shrimp. (JP)

    2. sibling species

      Knowlton, N. (1986). Cryptic and Sibling Species among the Decapod Crustacea. Journal of Crustacean Biology, 6(3), 356-363. doi:10.2307/1548175

      This previous work defines the term sibling species. According to Knowlton, sibling species are species that have been shown to be very closely related using biochemical techniques such as electrophoretic analysis. Sibling species are not the same species. This publication also uses electrophoretic analyses, known as starch gel electrophoresis, to differentiate between species of snapping shrimp. (JP)

    3. Low values indicate that transisthmian pairs showed little tolerant behavior or much intolerant behavior relative to intraoceanic pairs of the same taxa.

      Schein, H. (1975). Aspects of the aggressive and sexual behaviour of alpheus heterochaelis say. Marine Behaviour and Physiology, 3(2), 83–96. https://doi.org/10.1080/10236247509378498

      This previous work studies aggressive and sexual behavior in snapping shrimp. Although the snapping shrimps studied were found in North Carolina, their behavior reflects the behavior of the genus. Here they established that males seek females using chemical cues, and in general a male with a larger claw/larger body size favors larger females that can produce more offspring. Also, males with larger claws are stronger and can out compete smaller males. In relation to this publication, this previous work establishes a background of the behavior of the snapping shrimp. Understanding their natural behavior helps in understanding how the authors of this publication reached their conclusion. (JP)

    4. snapping shrimp genus Alpheus

      Sexual selection and dimorphism in two demes of a symbiotic, pair-bonding snapping shrimp Knowlton, N. (1980), SEXUAL SELECTION AND DIMORPHISM IN TWO DEMES OF A SYMBIOTIC, PAIR-BONDING SNAPPING SHRIMP. Evolution, 34: 161–173. doi:10.1111/j.1558-5646.1980.tb04802.x

      This previous work provides evidence on how differences between mates affects mate choice and, with environmental constraints, can lead to sexual dimorphism which is a distinct difference in size or appearance between the sexes of the same species. This study found that snapping shrimp are very aggressive and territorial to other shrimps of the same sex. By having these type of aggressive traits, compatibility would decrease as species are more separated. This supports one of the results found in this publication. (JP)

    5. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Knowlton, Nancy & Mills, DeEtta. (1992). The Systematic Importance of Color and Color Pattern: Evidence for Complexes of Sibling Species of Snapping Shrimp (Caridea: Alpheidae: AZ'heus) from the Caribbean and Pacific Coasts of Panama. Proceedings of the San Diego Society of Natural History. 18.

      This past publication explains how loosely related, or distantly related, species in the genus Afpheus Fabricius (snapping shrimp) can be distinguished based on color morphology such as differences in color patterns. This relates with this publication because both are related to the speciation of snapping shrimp in the Isthmus of Panama. Both publications find methods to differentiate between species; while this paper uses mtDNA and allozymes to compare genetic distance, the other paper uses careful analyses of color patterns to separate species. (JP)

    6. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Bermingham, E. & Lessios, H.A. (1993). “Rate Variation of Protein and Mitochondrial DNA Evolution as Revealed by Sea Urchins Separated by the Isthmus of Panama.” Proceedings of the National Academy of Sciences, 90(7): pp. 2734–2738.

      Another research was made in regards to the closure of Isthmus of Panama 3 MA based on changes in oxygen/carbon ratios in sea water. The main subject studied was sea urchins. Bermingham and Lessios compared mtDNA and protein divergence among three differ species of sea urchins--Diadema, Echinometra, & Eucidaris. Results concluded that protein divergence between Atlantic and Pacific sea urchin species only differed by 1 order of magnitude, so no significant difference. The Diadema species had an overlap of allele frequencies whereas the other two species displayed fixed loci for differ alleles of both shores, which may hint towards gradual genetic drift or mutations.This proves that other marine life besides the Alpheus shrimp community were also affected by a change in the environment via closure of Panama Isthmus.

      ~(J.D.A.)

    7. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Read, A., McTeague, J., & Govind, C. (1991). "Morphology and behavior of an unusually flexible thoracic limb in the snapping shrimp, Alpheus heterochelis". The Biological Bulletin, 181(1): pp. 158-168.

      This journal explains the morphology of the snapping shrimp Alpheus. Their second thoracic limb is thinner, flexible, bilaterally symmetrical, and possess larger ganglion. This type of limb is almost always active in regards to grooming and foraging for food. The major cheliped, or the larger claw, is used to produce loud popping noises as a defense mechanism against predators.

      ~(J.D.A.)

    8. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Knowlton, N. & Keller, B.D. (1982). "Symmetric Fights as a Measure of Escalation Potential in a Symbiotic, Territorial Snapping Shrimp." Behavioral Ecology And Sociobiology, 10(4): 289-292.

      This journal goes into detail the behavioral aspect of the Alpheus shrimp. This species readily defends its territory using its large snapping claw. Results gathered focused on symmetric fights of shrimps in regards to sex, size, and resources. According to this study, larger females are more likely to defend their anemone territories and showed more aggressiveness than the male shrimps. The losers of these contests experienced severe injuries by these large females than any other type of shrimps.

      ~(J.D.A.)

    9. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Svitil, K.A. (1993). "Oceans Divided". Discover, pp.1-2.

      A magazine article by Kathy Svitil talks about the closure of the Isthmus of Panama. She talked about how the rise of Panama 3.5 million years ago separated Atlantic and Pacific species before the land-bridge could even form. This was caused by the shift in tetonic plates, where the Pacific Ocean floor shifted underneath the Carribean plate before melting/solidifying by lava. She states how animals felt the influence of the rifts coming together, even quoting Nancy Knowlton on the speciation of snapping shrimps on either sides of Isthmus since these shrimps used to live in deeper depths of the ocean.

      ~(J.D.A.)

    10. Divergence in Proteins, Mitochondrial DNA, and Reproductive Compatibility Across the Isthmus of Panama

      Glynn, P.W. (1985). “El Nino-Associated disturbance to coral reefs and post disturbance mortality by Acanthaster planci.” Marine Ecology Progress Series, 26(17): pp. 295–300.

      Another study shows how in 1985 the coral reefs in eastern Pacific (Panama included) got ruined by El Nino due to very high water temperatures (average of 31 Celsius) and depth penetration (over 100 m). Since most habitats in coral reefs were destroyed, many species were easily exposed to predators. This may affect the results obtained by Mills and co. because barely a decade has passed for the marine habitats in Panama to recuperate.

      ~(J.D.A.)

    1. Genetic studies have also suggested that Sox10and Ednrb do not interact during murine melanocyte development (Hakami et al., 2006).

      Sox10 is expressed in melanoblasts, which are the precursors of melanocytes, that do not contain Ednrb. Ednrb is expressed in embryos that do not contain Sox10. Therefore, Sox10 expression does not depend on the expression of Ednrb. (DB)

    2. High VEGF levels are in turn associated with poor prognosis in human melanoma tumors (Giatromanolaki et al., 2003).

      Studies show that there is a high expression of VEGF in human melanoma tumors, indicating that VEGF can serve as a marker for melanoma prognosis. Moreover, tumors with a high vascular density (VD) were also associated with poor prognosis. (DB)

    3. Moreover, in situ melanomas appeared in adult skin grafts, while invasive melanomas developed in newborn skin grafts indicating that the susceptibility of skin to environmental tumor promoters is dependent on age (Berking et al., 2004).

      Exposure to ultraviolet (UV) radiation is a risk factor for the development of melanoma. Researchers have shown that people who sunburned in childhood are at a greater risk of developing melanoma than are people who sunburned in adulthood. This study suggests that age is associated with the susceptibility of skin to environmental carcinogens. (DB)

    4. Although Ednrb downregulation has been reported in some human melanoma cell lines (Eberle et al., 1999), other studies found Ednrb to be upregulated in most melanoma cell lines (Bittner et al., 2000; Ross et al., 2000). 

      There is an increase in the amount of Ednrb in most cell lines. This is significant because Ednrb expression is increased in melanoma metastases. (DB)

    5. This suggests that Ednrb may function to activate tyrosinase production indirectly by inducing the production or secretion of Kitl (Hou et al., 2004).

      Ednrb encodes a G-protein-coupled receptor that is necessary for the development of melanocytes. Studies have shown that Ednrb is not necessary for the development of early melanoblasts but is essential for the expression of the differentiation marker tyrosinase. Ednrb wild-type cultures must be able to generate the KIT ligand. Moreover, a soluble KIT ligand allows tyrosinase to be expressed in cultures that do not contain sufficient amounts of Ednrb. (DB)

    6. This increase in cell numbers in the treated cultures could not be accounted for solely by a proliferative effect, pointing to a possible role for Edn3 in the survival of melanoblasts from the NC (Opdecamp et al., 1998).

      Mutations in genes that code for Edn3 result in deficiencies in melanocytes. Edn3 serves as a stimulator of melanoblast proliferation and differentiation. When melanoblasts differentiate, they become melanocytes. (DB)

    7. Edn3 was most effective in promoting the long-term propagation of glia-melanocyte precursor cells as opposed to the other precursors (Real et al., 2006).

      Researchers have shown that individual melanocytes produce multipotent cells that are able to regenerate during consecutive subcloning. This indicates that the multipotent cells display stem cell qualities. Edn3 encourages the maintenance of the multipotent cells. Moreover, Edn3 stimulates the proliferation of melanoblasts, which are the precursors of melanocytes. (DB)

    8. In the absence of contact inhibition, cells treated with Edn3 were found to proliferate for two weeks without producing pigment (Lahav et al., 1996).

      Cells proliferate in the presence of Edn3. The cells that are produced are melanoblasts, which subsequently become melanocytes. (DB)

    9. It was first identified as a potent vasopressor derived from vascular endothelial cells (Yanagisawa et al., 1988).

      Researchers isolated Edn1 to determine its function. Edn1 was shown to be responsible for an increase in blood pressure. Expression of the gene was controlled by factors that affect blood vessels, suggesting that there is a cardiovascular control system. (DB)

  15. Oct 2017
    1. Marine reserves can clearly enhance exploited coral reef species that have relatively sedentary adult life-stages, in which some individuals live almost exclusively within reserve boundaries

      A study in 2 June 2009 conducted by Philip P. Molloy explored the relations with the age of the marine reserves and of the recovery of different species of fish. The studies showed that older marine reserves (15 years and older) were more effective than younger ones. They harbored more fish.

    1. People with scientific training are adopting these practices as well, either by offering services on sites such as Upwork or finding projects through their previous academic networks.
    1. stress-inducing focus on end products

      Our social work education accrediting organization fetishizes competencies, thereby inducing stress in instructors, which then gets passed along to the students. I use hypothes.is extensively and can directly observe the students transition from coping to engagement.

    1. Decide how to decide, ahead of time

      Step 1 in any process: decide how you are going to make decisions.