4,088 Matching Annotations
  1. Jun 2019
    1. illicit drug

      Substances that are addictive to the central nervous system.

      These substances are illegal to be possessed, have no documented therapeutic effect, and are referred to as drugs of abuse.

      Eg. Cocaine, Heroin

    2. marijuana

      ‘weed’ or ‘pot.’

      Read more about marijuana here: https://www.drugabuse.gov/publications/research-reports/marijuana/what-marijuana

    1. trophic downgrading

      Impacts from the loss of the top-level consumers.

    2. pervasive

      Widely felt.

    3. top-down forcing

      Impacts that top-level predators have on the levels of the food web below them.

    4. trophic

      Feeding relationships.

    5. biogeochemical cycles

      Complex cycles of nitrogen, sulfur, phosphorous, carbon, and water involving the atmosphere, land, water, and organisms.

    6. interdisciplinary

      Research involving more than one field of science, e.g. biology and chemistry.

    7. function

      How a system works.

    8. resilience

      How quickly a community is able to recover from a change in the environment.

    9. empirical

      Based on data.

    10. mass extinction events

      Periods of Earth's history when vast numbers of species went extinct in a short period of time.

    11. predation

      Killing another organisms for food.

    12. herbivory

      Eating only vegetation for food.

    13. abundance

      Number.

    14. distribution

      Location.

    15. ecosystems

      The interactions between organisms and the non-living environment (i.e. rocks, water) within an area.

    16. topology

      Structure.

    17. basins of attraction

      Conditions that allow for stability in an ecosystem.

    18. hysteresis

      When the direction of a ecosystem change cannot be reversed, i.e. an ecosystem cannot be returned to its previous state once it has gone through a phase shift.

    19. physicochemical

      Interactions of physiology and chemistry.

    20. flux

      Change.

    21. perturbed

      Altered.

    22. extirpated

      Removed.

    23. weakly motile

      Not able to move far.

    24. autotrophs

      Self-feeding organisms such as plants, algae, many protists, and some bacteria.

    25. regime shifts

      Changes in abundance or dominance of species within an ecosystem.

    26. “natural experiments”

      Data collected from unintended consequences seen in nature.

    27. mesopredators

      Predators found in the middle of the food web—that is, they both eat prey and are eaten as prey.

    28. megaherbivores

      Large, plant-eating organisms.

    29. aggregate

      Collective.

    30. alternative stable states

      A different persistent community structure from the original in an ecosystem, typically resulting from a disturbance.

    31. recruitment failure

      Inability of seeds to germinate.

    32. graminoid

      Grass-like plants.

    33. trophic cascades

      Also known as top-down controls, these refer to the effects of predators that propagate downward through food webs across multiple trophic levels—where trophic level refers to an organism's position in the food chain.

    1. zona incerta (ZI)

      A part of the brain.

      The function of this area is poorly understood but is thought to regulate behavior of an animal in response to internal (such as hunger) and external (such as pain) sensory cues.

    2. γ-aminobutyric acid (GABA)

      An inhibitory neurotransmitter. Neurons communicate with each other by releasing neurotransmitters. Neurons respond to inhibitory neurotransmitters by reducing their activity.

    3. Intraperitoneal CNO

      The CNO was injected into the peritoneum, the thin membrane that lines the walls of the abdominal cavity. It travels through the circulation and crosses the blood brain barrier and affects its target cells.

    4. type A GABA (GABAA) receptor antagonist bicuculline (Bic)

      A light-sensitive competitive agonist of GABA<sub>A</sub> receptors. It was originally isolated and identified over 40 years ago in the Dicentra cucullaria plant.

    1. Parkinson's disease

      A progressive degenerative disorder primarily impacting motor control that can lead to tremors or stiffness. Pathologically characterized by the loss of dopamine-secreting neurons in two parts of the brain (the substantia nigra pars compacta and basal ganglia), as well as the presence of Lewy bodies—aggregates of a protein called alpha synuclein contained within the neuron.

  2. May 2019
    1. motivational valence

      The degree to which something is perceived as pleasurable (positive valence) or unpleasant (negative valence).

    2. excited by

      Activated by.

    3. Anterograde

      Occurring along the nerve processes away from the neuron body, as opposed to retrograde.

    4. lateral hypothalamic neurons

      A region of the brain in close proximity to ZI known to promote food intake.

    5. glutamate

      An excitatory neurotransmitter, which causes neurons to become activated.

    6. parasubthalamic nucleus

      A part of the brain located below the thalamus, which functions in motor control.

    7. ghrelin

      A hormone produced in the gut in response to food deprivation.

      Also known as the "hunger hormone," ghrelin increases appetite and food intake and energy storage.

    8. excitatory

      Neurons that express excitatory neurotransmitters cause downstream neurons to become activated.

    1. germinal center

      Germinal centers are areas in the lymph nodes and spleen where B cells reside. Within these centers B cells replicate, mature and prepare to create antibodies.

    2. epitopes

      An antigen on the surface of the virus that antibodies can attach to.

    3. effector phenotypes

      The characteristics that are representative of activated T cells.

    4. T follicular helper (TFH

      This subset of T cells that aid in the production of antibodies by activating B cells.

    5. antigen

      An antigen is a part of a pathogen that stimulates an immune response. This may be a protein, lipid, or a carbohydrate.

    6. B cells

      B cells are immune cells that produce antibodies.

    7. induced

      In molecular genetics when a gene is induced, it means the amount of mRNA transcripts from that gene is increased.

    8. elucidated

      Elucidated is another way of saying explained or investigated.

    9. cytokines

      Cytokines are proteins that are released by immune cells to activate the immune response in other cells.

      Example: When a cell is infected with a virus, it can release the cytokine interferon to signal neighboring cells of an incoming viral attack. This allows the neighboring cells to increase production of anti-viral proteins.

    10. choline acetyltransferase (ChAT),

      Choline acetyltransferase is a protein that is responsible for the creation of acetylcholine.

    11. prototypic

      Prototypic means the original model in which further knowledge is based off of.

      Since acetylcholine was the first neurotransmitter discovered, its function/ behavior is what all other neurotransmitters are based off of.

    12. vasodilation

      Vasodilation in when blood vessels expand. This is an important response to viral infection because it allows immune cells to reach the site of infection.

    13. ablated

      Ablated in this context means that mice did not have vasodilation in response to viral infection.

    14. IL-21

      IL-21 is a protein released by CD4 T cells that activates cytotoxic T cells and NK cells.

    15. CD8+

      A CD8 positive T cell (referred to as a cytotoxic T cell) is responsible for killing intracellular pathogens, cancer cells and other damaged cells.

    16. CD4+

      A CD4 positive T cell (referred to as a helper T cell) is a subset of T cells responsible for activating and directing different types of immune cells.

    17. lymphocyte

      T cells, B cells and Natural Killer (NK) cells are immune cells that are referred to as lymphocytes.

    18. T cell

      A T cell is a type of immune cell responsible for directing the adaptive immune system's response to infection, allergy and cancer.

      • note: think of the T cell as a general of an army.
    19. neurotransmitter

      A neurotransmitter is a molecule released by nerves to communicate with other nerves, muscles fibers, or organ systems.

    1. catalysis

      Catalysis is the initiation and acceleration of a chemical reaction.

      In this case, the authors point to KDM6B as the catalyst for Dmrt1 expression and thus male sex development.

    2. morphology

      Morphology describes biological structures.

    3. meiotic

      Relating to cell division that gives rise to sex cells.

    4. histone H3 lysine 27 (H3K27) demethylase KDM6B

      DNA is wrapped around proteins called histones for the organization and compaction of eukaryotic genomes.

      The proteins that make up histones have multi-peptide "tails" that can be modified by small chemical groups like methyl or acetyl additions. These groups are added or removed by specific proteins, such as KDM6B.

    5. ectopic

      Ectopic describes events occurring in locations that do not naturally have such events.

      For example, expression of a brain-specific gene in a toenail would be considered ectopic gene expression.

    6. testicular Sertoli cell

      Male sex cells that are required to form testes and sperm.

    7. primordial germ cells

      Progenitor sex cells that go on to make all the reproductive cells in an organism.

    1. will stand for no amino acid—that is, will be nonsense

      As a general rule, there are four kinds of codons: codons that initiate the reading frame, codons that stop the reading frame, codons that code for amino acids to make proteins, and codons that don't code for anything at all (called nonsense codons).

    2. rII locus

      A locus is a specific location or section of genetic material. The r<sub>II</sub> locus is one of three loci composing the genetic material of bacteriophage T4 (described below).

    3. protein synthesis

      The process of making proteins.

    4. RNA

      Ribonucleic acid, or RNA for short, is one class of genetic material. It is an example of a nucleic acid molecule.

      RNA is composed of three chemical building blocks: a sugar (called ribose), a phosphate group, and a nitrogenous base.

      RNA has many functions in a cell, and scientists are still studying RNA today. Some hope that RNA might be the key to disease prevention.

      https://cen.acs.org/pharmaceuticals/decade-RNA/97/web/2019/01

    5. enzyme

      A special class of proteins which catalyze (i.e., cause or speed up) a chemical reaction in biological systems.

      Remember, that a protein is a chain of amino acids.

    6. amino acid

      The chemical building blocks of proteins. All amino acids contain an amine group (-NH<sub>2</sub>) and a carboxylic acid group (-COOH).

      https://www.neb.com/tools-and-resources/usage-guidelines/amino-acid-structures

    7. Deductions

      Crick relies on deductive reasoning to make his argument for the nature of the genetic code.

      Deductive reasoning draws specific conclusions from general principles or premises, whereas inductive reasoning infers general principles from specific instances.

    8. 2',3' hydroxyls on the sugar.

      Hydroxyls are -OH groups and are found on the sugar ribose on the second and third carbon. In RNA, only one chemical unit in the entire strand has a hydroxyl on both the second and third (2' and 3') carbon.

      Check out this image to identify the hydroxyls found on second and third carbon.

    9. "right-hand" end

      Just as your left and right hands are distinct mirror images, certain molecules have distinct mirror images, too. When a molecule has a distinct mirror image, we say the molecule is chiral.

      All sugars in the body are "right handed." On a strand of genetic material, the sugars are linked together such that only one end of the chain is "handed."

    10. poly (U,C)

      Crick defines poly(Y, Z) as a DNA strand with equal amounts of two bases "Y" and "Z" in random order. Here, poly(U, C) is then a strand of genetic material with equal amounts of uracil and cytosine in random order.

    11. polyuridylic acid

      An RNA molecule in which every base is uracil.

    12. synthetic RNA

      RNA that is made in the lab as opposed to natural RNA found in a cell.

    13. acridines

      An organic molecule that is not naturally found in cells, as they are substituted derivatives of the parent ring.

      Acridines were previously used in some dyes and many have antiseptic properties, but usage largely stopped since acridines are also a skin irritant.

    14. bacteriophage T4

      A bacteriophage is a type of virus that infects bacteria. The T4 bacteriophage is a specific bacteriophage that infects E coli. Bacteriophages—like all living organisms—have genetic material.

    15. A and B cistrons

      A section of DNA or RNA that codes for a specific chain of amino acids, or "polypeptide chain." Cistron is synonymous with gene, meaning A and B cistrons are two different genes. The term cistron has largely fallen out of favor.

    16. cistron

      A section of DNA or RNA that codes for a specific chain of amino acids, or "polypeptide chain." Cistron is another word for gene. As such, it's not normally used much nowadays.

    17. the amino end

      Imagine kids lined up holding hands: The line leader will have no one to hold her left hand and the caboose will have no one to hold her right hand.

      Amino acids on a protein have a similar feature. The first amino acid will have an amine group exposed and the last amino acid will have an acid group exposed. The "amino end" refers to the end of the strand where the amine group is exposed.

    18. Gamow's

      George Gamow (1904–1968) was a theoretical physicist. Curious about the natural world, he was often in contact with scientific giants outside of physics, such as Crick. Despite his inexperience in chemistry and biology, Gamow learned about these fields and ultimately influenced their progress. Gamow is just one of many historical examples of an outside, non-expert perspective having a profound influence on a difficult problem.

    19. Watson

      James Watson (1928–) co-discovered the structure of DNA with Francis Crick (the author of this paper).

      https://www.nobelprize.org/prizes/medicine/1962/watson/biographical/

    20. Beadle

      George Beadle (1903-1989) was a Nobel Prize-winning scientist credited with discovering the inherent connection between genes (DNA) and enzymes (proteins).

      https://www.nobelprize.org/prizes/medicine/1958/beadle/biographical/

    21. genetic recombination

      The exchange of genetic material between two different organisms. In the case of T4 bacteriophage, this is done by infecting a single E. coli cell with multiple phages. The phage genomes then recombine and produce new variants.

    22. chemically induced mutations

      Chemically induced mutations occur when a scientist uses chemicals to alter a DNA sequence.

    23. messenger RNA

      A class of RNA that acts as a messenger of genetic information, delivering the code from DNA to a ribosome where it is translated into amino acids, eventually resulting in a polypeptide or protein.

    24. a sequence of 20 or more things is determined by a sequence of four things of a different type.

      That is, a specific sequence of bases encodes a specific sequence of amino acids. Within this code, which is used by all living organisms, there are only four kinds of bases and 20 kinds of amino acids.

    25. bases

      Here, bases refer to the chemical pendants—side groups of molecules—that are found on the backbone of nucleotides. Nucleotides consist of a sugar called deoxyribose, a phosphate group, and one of five bases.

      An example of a base is guanine.

    1. niche broadening

      A niche is an organism's functional role in its ecosystem. Niche broadening is when an organism expands this role to encompass more interactions, behaviors, and food sources to promote their survival.

    2. climatic seasonality

      Weather patterns associated to various seasons

    3. seed dispersal events

      The distribution of a seed by being eaten by an animal and later excreted in its waste.

    4. modular

      Organized into distinct, independent groups

    5. perturbations

      A deviation or disturbance from the norm.

    6. supergeneralist

      A species that interacts with multiple groups of species in ecological networks

    7. insular

      From an island

    8. archipelago

      A group of islands

    9. Anthropocene

      The current geological age where human activity is the dominant influence on climate change and the environment.

    1. nanoscrolls

      A nanomaterial structure with a spiral wrapped geometry. Think of a scroll, or a roll of paper, on the nanoscale.

    2. tribopair

      Refers to the components in a friction system. Here, the DLC coated ball and the graphene-plus-nanodiamonds constitute the tribopair.

    3. energetic barriers

      The minimum energy needed to overcome the attractive forces between atoms at the sliding interface is referred to as energertic barriers.

    4. dispersive interlayer interactions

      This force occurs due to the out of plane interaction between adjacent graphene layers.

    5. van der Waals forces

      A general term used to describe the intermolecular forces of attraction between molecules.

      See more from Khan Academy

    6. dangling bonds

      An unsatisfied valence of an immobilized atom.

    7. transmission electron microscopy (TEM)

      TEM is an imaging technique capable of generating high resolution (nanometer scale) images of a sample.

    8. dry nitrogen

      Nitrogen gas with no water vapor.

    1. F

      Another measure of statistical difference between the means of different groups.

    2. Cohen’s d

      A statistical measure of effect size.

    3. t

      The t statistic is used with the T test, which determines if there is a difference between the average result of two different groups.

    4. racial achievement gap

      The difference in performance (for example on standardized tests) between minority students and white students.

    5. gateway courses

      Classes that students are required to take before taking more advanced courses in the field.

    6. snowballing effect

      A process that may start small, but build on itself becoming larger and more serious.

    7. interactive engagement approaches

      Teaching strategies in which students are challenged to think about the material on their own and with other students, while the instructor acts as a guide.

    8. residual

      Amount left unexplained by other variables.

    9. grand mean

      The mean of the mean of several sub-samples.

    10. moderation effect

      Moderating variables are variables that affect the direction of strength of a relationship between dependent and independent variables (in this case, the level of endorsement of stereotype threat is the moderating variable).

      A moderating effect is the result of the influence of a moderating variable.

    11. main

      A main effect is the effect of one independent variable (in this case gender) on the dependent variable (in this case beginning-of-semester FMCE scores), and ignores the effects of other independent variables.

    12. nationally normed standardized test

      A standardized test that is given across the country so that an average performance can be determined for the country.

    13. modal grades

      The "mode" refers to the number that occurs most frequently in a set.

      The "modal grade" is the course grade that occurred most frequently.

    1. orthologs

      Orthologs are derived from a common ancestor gene and have some degree of sequence similarity

      Image credit: https://www3.beacon-center.org/blog/2015/03/23/beacon-researchers-at-work-same-behavior-same-genes/

    2. fidelity

      How specifically an enzyme carries out its function. We can say that Cas13b has high fidelity because it produced very few off-targets in the knockdown experiment (see Figures 1E, 1F, and 1G).

    3. structure-guided protein engineering

      When researchers want to modify a protein to improve a particular feature, they can use the knowledge of the protein's 3D structure to identify and modify key amino acids in the sequence.

    4. coverage

      When you sequence a genome, you do it in pieces rather than in a single, continuous stretch. This is similar to cutting the genome up and then putting it back together again, like a puzzle. Each base may be read multiple times and be a part of multiple sequences—comparing pieces to see where they overlap is how the full genome is reconstructed. The number of times a base is read is called the "coverage," and higher coverage leads to a more accurate sequence.

    5. adeno-associated viral (AAV) vectors

      Adeno-associated virus (AAV) is a human virus that is present in 80% - 90% of the adult population but does not cause any disease. This virus has been extensively used as a biomolecular tool because it is small and has low risk of genome integration and causing unwanted mutations.

    6. the ClinVar database

      ClinVar is an archive that collects data about the relationship between gene variants and phenotypes. It contains more than 400,000 records.

      ClinVar is free to use—try looking up information about AVPR2. Search for AVPR2 to find out more about the 878G>A mutation that the authors looked at.

    7. Fanconi anemia

      Fanconi anemia (FA) is a rare genetic condition resulted from nonfunctional DNA repair mechanisms.

      Because DNA repair is vital for every cell in the body, all organs are affected when repair mechanisms don't function properly. Organs that contain frequently dividing cells (such as skin) are the most affected. People with Fanconi anemia have bone marrow defects, organ abnormalities, and an increased risk of some cancers.

    8. FANCC

      FANCC codes for a protein involved in the Fanconi anemia (FA) disease pathway.

      This pathway is activated when the cell DNA gets damaged. The FANCC protein is a part of a complex responsible for recognizing this DNA damage and activating repair mechanisms.

    9. PPIB

      Stands for, Peptidylprolyl Isomerase B (also known as Cyclophilin B), which codes for a protein that regulates protein folding in the cytoplasmic reticulum. Some mutations of PPIB result in impaired bone development.

    10. DNA base editors, consisting of a fusion between Cas9 nickase and cytidine deaminase, can mediate efficient cytidine-to-uridine conversions within a target window and substantially reduce the formation of double-strand break–induced indels

      DNA base editing is a technique which allows precise conversion of one nucleotide into another without any template sequence.

      A base editor is a fusion protein made up of a protein that recognizes specific DNA sequences (for example, Cas9), and a deaminase that can convert one amino acid to another (i.e., cytidine [C] to uridine [U] or adenosine [A] to inosine [I]).

      Because of the geometry of the proteins, this conversion can only happen in a certain range of nucleotides, called the target window.

    11. frame shifts

      Genes are transcribed into proteins by codons, which are made up of sequences of three amino acids. Mutations that occur in numbers divisible by three will not affect the reading frame, but those not divisible by three will cause a shift in the reading frame. Generally, a mutation in-frame will not disrupt the protein function and can be handled by the cell. A frame-shift mutation will completely inactivate a protein and can be very detrimental to cellular function in some cases.

      For example:

      Original sequence: THE CAT WAS RED

      Frame shift mutation: ATH ECA TWA SRE D

      Non-frame shift mutation: THE BIG CAT WAS RED

    12. Cpf1

      Cpf1 is a nuclease that is analogous to Cas9.

      Cpf1 differs from Cas9 in a number of ways. The most important one is that when Cpf1 cuts DNA, it leaves overhangs. It also requires different PAM sequences, which are short sequences that help the system distinguish self DNA from non-self DNA.

      Cfp1 has the potential to be more accurate than Cas9, and can sometimes be used when there are no sequences that Cas9 can use as a target.

    13. Precise nucleic acid–editing technologies

      These techniques allow researchers to modify a chosen nucleic acid sequence.

      The most widely used technologies are TALENs (transcription activator-like effector nucleases), ZFNs (zinc finger nucleases) and CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9).

      CRISPR is the most popular since it can be programmed to new sequences using a guide RNA, whereas other tools must be engineered at the protein level, which is difficult and time consuming. The focus of this paper is a variation of CRISPR that uses Cas13.

    1. polygenic

      Referring to traits that are controlled by two or more genes at different places on different chromosomes.

    2. synteny

      When two or more genomic regions are derived from a single ancestor.

    3. directional selection

      Type of natural selection where one phenotype is favored over others. This causes the frequency of alleles to shift in the direction of that phenotype.

    4. Introgressive hybridization

      Movement of gene from one species into the gene pool of another species by the repeated crossing of a hybrid with one of its parents.

  3. Apr 2019
    1. heterozygotes

      An individual that has two different forms of a particular gene on homologous chromosomes.

    2. homozygous

      Referring to a particular gene in which all of the alternative forms of that gene are identical on homologous chromosomes.

    3. missense mutation

      Where a single nucleotide base is changed which results in a different amino acid.

    4. phenotype

      Observable characteristics of an individual.

    5. single-nucleotide polymorphism

      Refers to a variation in a single base pair within a DNA sequence.

    6. intrinsic transcriptional activity

      An essential copying of DNA into RNA, the first step of gene expression.

    7. genome-wide fixation index

      Measure of the genetic differences in and among populations due to genetic structure.

    8. selection differential analysis

      Measures the difference between the average genetic value of selected organisms and the average genetic value of all the organisms in the population.

    9. multiple regression

      Used to explain the relationship between a dependent variable and one or more independent variables.

    10. heritable

      Referring to traits that are transmissible from parent to offspring.

    11. taxa

      Groups of one or more populations.

    12. phylogenetic

      Referring to the study of the evolutionary history and relationships of various biological species.

    13. speciation

      The formation of new species.

    14. haplotypes

      Groups of genes inherited from a single parent.

    15. genomic analysis

      The process of measuring or comparing features such as DNA sequences, variation of structures, gene functions, or gene expression.

    16. adaptive radiation

      Event in which a lineage rapidly diversifies into more species with different adaptations. These events lead to speciation.

    17. morphological

      Relating to the structure or form of living organisms.

    18. character displacement

      When two competing species overlap in habitat, natural selection may drive one population to use resources that are not used by individuals of the other population. This allows two similar species to coexist.

    19. Ecological

      Describing a branch of biology that deals with relationships and interactions among organisms and the environment.

    1. an order of magnitude

      About 10 times. Let's say zeolites (a conventional adsorbent) could adsorb 2 liters, then MOF-801 could adsorb an order of magnitude greater—that is, 20 liters.

    2. noncondensables

      Gases that cannot easily be turned into liquids. In this case, noncondensables refers to the gases present in air which are mainly dioxygen, dinitrogen, and argon.

    3. global horizontal irradiation

      The amount of solar light received by a horizontal surface on Earth.

    4. solar absorptance of 0.91

      The fraction of the sun radiation that penetrates the surface. A solar absorptance of 0.91 means that 91% of the sun's radiation penetrates the material and is converted to heat.

    5. face-centered cubic topology

      Describes the 3D geometry of the MOF. MOF-801 is constituted of a repetition of cubes having one cluster in each corner and each center of the faces. Figure 1B shows one of these small cubes constituting the repeating unit of the MOF.

    6. diurnal

      During the day. It is the opposite of nocturnal, which means during the night.

    7. porosity

      The ratio of the cavities' volume to the total volume of the material. MOFs are made of microscopic crystals, which are responsible for the presence of these cavities. Porosity can range from 0 to 1, a porosity of 0 meaning that there are no cavities within the structure.

    8. microcrystalline

      Made of atoms and molecules arranged in a highly ordered microscopic structure that extends in every direction.

    9. 1 sun

      Unit of light intensity corresponding to 1000 watts per square meter. For reference, if you stood one meter away from a standard 60-watt light bulb, the light intensity would be equal to about 4.8 watts per square meter.

    10. [Zr6O4(OH)4(fumarate)6]

      The chemical composition of MOF-801. This specific MOF is based on zirconium (Zr) metal ions linked together by fumarate molecules, which are small organic compounds made of carbon, oxygen, and hydrogen.

    1. wear debris

      Wear is the progressive loss of materials from contacting surfaces relative in motion. The wear process results in generation of debris—or particles—of various size, shape, color distributions, and chemical composition.

    2. mechanical strength

      Refers to the material's resistance to failure by fracture or deformation when a load is applied.

    3. sp3/sp2 bonded carbon

      Hybridization is the combining or mixing up of atomic orbitals (an expected region of electron density around an atom) to form new hybrid orbitals that have geometries suitable to form bonds. Electrons can be found in s, p, d and f orbitals. When an s orbital combines with three p orbitals, it results in four sp3 hybridized orbitals. Similarly, the combination of an s orbital with two p orbitals gives rise to three sp2 hybrid orbitals.

      Learn more about hybrid orbitals with these videos from Khan Academy.

    4. defects

      Perfect crystal is an idealization and in real materials, atom arrangements do not follow perfect crystalline patterns. Crystal defects can be due to missing atoms, introduction of an impurity atom, broken crystal pattern along fault lines or due to the joining of distinct crystal planes.

    5. incommensurability

      Misaligned or misfit.

    6. highly oriented pyrolytic graphite (HOPG)

      A high purity graphite material with high degree of preferred crystallographic orientation.

    7. macroscopic

      Relating to the large-scale, likely visible to the human eye.

    8. nanoscale

      Refers to dimensions less than 100 nanometers (where one nanometer is one billionth of a meter).

    9. mesoscopic

      This region is an intermediate between atomic and macroscopic scales.

    10. coefficient of friction

      The ratio of the frictional resistance force to the normal force. When two objects are in contact, the force which presses the surfaces together is called normal force.

    11. diamondlike carbon (DLC)

      A carbon material that exhibits many of the desirable properties of the diamond material.

    12. graphene

      The building block of graphite, which is used in pencil tips. Graphene is a one atom thick layer of carbon atoms arranged in a hexagonal lattice (atoms are arranged at the corners of a hexagon). The thickness of graphene is one million times less than that of a single human hair. Graphene is the world's first two dimensional material and the 2010 Nobel prize in Physics was awarded for its discovery.

      Source: Wikimedia

    13. superlubricity

      The state of near-zero friction at the sliding interfaces of two contacting solid surfaces is called superlubricity. In superlubric regimes, the extent of physical and/or chemical interactions is extremely small and hence the surfaces can slide over one another without causing much friction.

    14. quasi-2D ordered

      Quasicrystals are materials with perfect long-range order, but with no three-dimensional translational periodicity of crystals.

    1. phylogenetic

      Referring to the study of the evolutionary history and relationships of various biological species.

    2. morphological

      Relating to the structure or form of living organisms.

    3. interspecific competition

      Individuals of different species compete for the same resources.

    4. adaptive radiations

      Events in which a lineage rapidly diversifies into more species with different adaptations. These events lead to speciation.

    5. speciation

      The formation of new species.

    6. heritability

      A statistic that describes how much variation of a specific trait can be attributed to genetics. With these finches, it's a measure of how well differences in beak genes account for differences in beak sizes.

    7. natural selection

      Process that describes how species adapt to their environment. The organisms that are best adapted tend to survive and reproduce.

    8. ecological

      Describing a branch of biology that deals with relationships and interactions among organisms and the environment.

    9. character displacement

      When two competing species overlap in habitat, natural selection may drive one population to use resources that are not used by individuals of the other population. This allows two similar species to coexist.

    1. polarity of the NAO

      Polarity means to have two opposite or contradictory tendencies or aspects. In this case, the North Atlantic Oscillation (NAO) has both a warm phase and a cool phase, and convection (ocean mixing) differs between these conditions.