WikiJournal of Science

Brace roots (roots developing from aerial stem nodes) are a type of adventitious root that develop from aboveground stem nodes in many monocots. Brace roots may remain aerial or penetrate the soil as they perform root functions such as anchorage and resource acquisition. Although brace root development in soil or aerial environments influences function, a lot is still unknown about how their anatomy, architecture and development contributes to their function. This article summarizes the current state of knowledge on brace roots.

In differential geometry, a field in mathematics, a Poisson manifold is a smooth manifold endowed with a Poisson structure. The notion of Poisson manifold generalises that of symplectic manifold, which in turn generalises the phase space from Hamiltonian mechanics. A Poisson structure (or Poisson bracket) on a smooth manifold is a function on the vector space of smooth functions on , making it into a Lie algebra subject to a Leibniz rule (also known as a Poisson algebra). Poisson structures on manifolds were introduced by André Lichnerowicz in 1977 and are named after the French mathematician Siméon Denis Poisson, due to their early appearance in his works on analytical mechanics.

Play behaviour in non-avian reptiles is poorly understood compared to mammals and birds. No previous reports provide systematic data regarding play-like behavior in the third most popular non-avian pet reptile, the leopard gecko (Eublepharis macularius). Leopard geckos are known to engage with enrichment of novel items, and anecdotal observation by pet owners report high activity and play-like behaviour. An adult leopard gecko kept as a companion animal was provided with a running wheel to formally investigate possible play behaviour. Video recordings and a cycle counter attached to the running wheel were used to create an ethogram of one pet leopard gecko. The animal interacted with the wheel 16% of each measured day, in 11 wheel interaction episodes on average per measured day. The mean total distance measured by the cycle counter was 124 meters per measured day which surpasses the daily movement distance of some similar-sized diurnal lizards. The pattern of results indicates that the leopard gecko’s wheel use met all five previously established criteria for locomotion play, and showed that the leopard gecko to sometimes have high activity levels. These data suggest that when kept as a pet, given a running wheel or possibly other enrichment item, small reptiles such as leopard geckos engage in locomotion play. However, further studies with more individuals should be done to confirm this and investigate the possible physiological benefits of exercise.
非鳥類型爬虫類の遊び行動は、哺乳類や鳥類に比べてあまり理解されていない。また、非鳥類型爬虫類の中で、家庭用の愛玩動物として3番目に人気のあるヒョウモントカゲモドキ(Eublepharis macularius)の遊び行動に関する系統的なデータはこれまで報告されていない。ヒョウモントカゲモドキは目新しいものを与えることで興味を示すことが知られており、飼育者による逸話的観察によると、高い活動性と遊びのような行動が報告されている。当研究ではコンパニオンアニマルとして飼育されている成体のヒョウモントカゲモドキに回し車を与え、遊び行動の可能性を調査した。ヒョウモントカゲモドキ1匹のエソグラムを作成するために、ビデオ録画と回し車に取り付けたサイクルカウンターを使用した。その結果、各測定日の16％、1日平均11回の回し車とのインタラクションを行ったことが確認された。サイクルカウンターで測定された平均総距離は1日あたり124mで、これは同サイズの昼行性トカゲの1日の移動距離例を上回るものであった。この結果から、ヒョウモントカゲモドキの回し車の使用は、これまでに確立されているロコモーションによる遊びの5つの基準をすべて満たしており、ヒョウモントカゲモドキは時に高い活動レベルを持つことがわかった。これらのデータは、ペットとして飼育されているヒョウモントカゲモドキのような小型爬虫類に、回し車やその他のエンリッチメント・アイテムを与えることで、ロコモーションによる遊びを行うことを示唆している。ただし、当結果を最終的に結論づけること及び運動による生理学的な利点の可能性を調査するためには、より多くの個体でさらなる研究を行う必要がある。

In survey research, the design effect is a number that shows how well a sample of people may represent a larger group of people for a specific measure of interest (such as the mean). This is important when the sample comes from a sampling method that is different than just picking people using a simple random sample. The design effect is a positive real number, represented by the symbol . If , then the sample was selected in a way that is just as good as if people were picked randomly. When , then inference from the data collected is not as accurate as it could have been if people were picked randomly. When researchers use complicated methods to pick their sample, they use the design effect to check and adjust their results. It is also used when planning a study in order to figure out how many people should be in the sample.

In psychology and neuroscience, multiple object tracking (MOT) refers to the ability of humans and other animals to simultaneously monitor multiple objects as they move. It is also the term for a laboratory technique used to study this ability. In an MOT study, a number of identical moving objects are presented on a display. Some of the objects are designated as targets while the rest serve as distractors. Study participants try to monitor the changing positions of the targets as they and the distractors move about. At the end of the trial, participants typically are asked to indicate the final positions of the targets. The results of MOT experiments have revealed dramatic limitations on humans' ability to simultaneously monitor multiple moving objects. For example, awareness of features such as color and shape is disrupted by the objects' movement.

Non-canonical base pairs are planar hydrogen bonded pairs of nucleobases, having hydrogen bonding patterns which differ from the patterns observed in Watson-Crick base pairs, as in the classic double helical DNA. The structures of polynucleotide strands of both DNA and RNA molecules can be understood in terms of sugar-phosphate backbones consisting of phosphodiester-linked D 2’ deoxyribofuranose (D ribofuranose in RNA) sugar moieties, with purine or pyrimidine nucleobases covalently linked to them. Here, the N9 atoms of the purines, guanine and adenine, and the N1 atoms of the pyrimidines, cytosine and thymine (uracil in RNA), respectively, form glycosidic linkages with the C1’ atom of the sugars. These nucleobases can be schematically represented as triangles with one of their vertices linked to the sugar, and the three sides accounting for three edges through which they can form hydrogen bonds with other moieties, including with other nucleobases. As also explained in greater details later in this article, the side opposite to the sugar linked vertex is traditionally called the Watson-Crick edge, since they are involved in forming the Watson-Crick base pairs which constitute building blocks of double helical DNA. The two sides adjacent to the sugar-linked vertex are referred to, respectively, as the Sugar and Hoogsteen (C-H for pyrimidines) edges. Each of the four different nucleobases are characterized by distinct edge-specific distribution patterns of their respective hydrogen bond donor and acceptor atoms, complementarity with which, in turn, define the hydrogen bonding patterns involved in base pairing. The double helical structures of DNA or RNA are generally known to have base pairs between complementary bases, Adenine:Thymine (Adenine:Uracil in RNA) or Guanine:Cytosine. They involve specific hydrogen bonding patterns corresponding to their respective Watson-Crick edges, and are considered as Canonical Base Pairs. At the same time, the helically twisted backbones in the double helical duplex DNA form two grooves, major and minor, through which the hydrogen bond donor and acceptor atoms corresponding respectively to the Hoogsteen and sugar edges are accessible for additional potential molecular recognition events. Experimental evidences reveal that the nucleotide bases are also capable of forming a wide variety of pairing between bases in various geometries, having hydrogen bonding patterns different from those observed in Canonical Base Pairs (Figure 1). These base pairs, which are generally referred to as Non-Canonical Base Pairs, are held together by multiple hydrogen bonds, and are mostly planar and stable. Most of these play very important roles in shaping the structure and function of different functional RNA molecules. In addition to their occurrences in several double stranded stem regions, most of the loops and bulges that appear in single-stranded RNA secondary structures form recurrent 3D motifs, where non-canonical base pairs play a central role. Non-canonical base pairs also play crucial roles in mediating the tertiary contacts in RNA 3D structures.

Internet Protocol version 4 (IPv4) is an internetwork protocol that is active at the internet layer according to the TCP/IP model, it was developed in 1981 within a project managed by Defense Advanced Research Projects Agency. In the following years, the use of IPv4 grew to dominate data networks around the world, becoming the backbone of the modern Internet. In this survey, we highlight the operation of the protocol, explain its header structure, and show how it provides the following functions: Quality of service control, host addressing, data packet fragmentation and reassembly, connection multiplexing, and source routing. Furthermore, we handle both address-related and fragmentation-related implementation problems, focusing on the IPv4 address space exhaustion and explaining the short and long terms proposed solutions. Finally, this survey highlights several auxiliary protocols that provide solutions to IPV, namely address resolution, error reporting, multicast management, and security.

This study examines the existing social license of the forest products industry in a rural community in Michigan, located in the northern midwestern United States. This is accomplished through a series of interviews with industry and community stakeholders, aimed at understanding how they view social license and its impacts. Perceptions of natural resource management and community relations are highly related to the community's history with industries, relationships with place, and perspectives on what work is of value. The results suggest that social license varies spatially, and it is the place-based context that allows local industry to have a higher degree of license than non-local industry actors. Thus, social license is spatially contingent, based on particular socio-spatial and historical contexts. In this paper, we articulate how this spatial and historical contextualization shapes perceptions of acceptable operating practices. This paper offers refinement of the concept of social license while also considering how natural resource based industries can successfully meet evolving management challenges when their social license may be vulnerable to disturbances. Having an adequate social license is an undeniable asset for industry, while an inadequate social license is a liability. Stakeholders have the ability to damage or halt industry operations, often with just cause in the face of natural resource extraction and exploitation. Our evaluation of social licenses intends to shed light on the conditions that precipitate such conflicts.

The National Center for Science and Engineering Statistics (NCSES) is one of the thirteen principal statistical agencies of the United States and is tasked with providing objective data on the status of the science and engineering enterprise in the U.S. and other countries. NCSES sponsors or co-sponsors data collection on 15 surveys and produces two key publications: Science and Engineering Indicators, and Women, Minorities, and Persons with Disabilities in Science and Engineering. Though policy-neutral, the data and reports produced by NCSES are used by policymakers when making policy decisions regarding STEM education and research funding in the U.S. Given NCSES’s importance to the science and engineering community, raising awareness of NCSES and increasing participation by individuals in STEM fields is an important priority.

Bacteriophage T4 is a virus that infects Escherichia coli, having dimensions of 90 nm in width and 200 nm in length (head and tail in extended form). It is a quite common model organism that has been studied for a century by many important virologists, and even Watson and Crick after their elucidation of DNA. Structural characterisation of the bacteriophage’s individual proteins began in the 1980s, and complexes of multiple proteins in the 1990s. However, it has not yet been possible to structurally characterise the complete phage in atomic detail (though some have begun to come closer) with multiple overall schematic models published. The increasing power of computers and the RCSB structural database have made possible the construction of a single combined model of the entire bacteriophage T4 organism with atomic resolution components as described here.

The affine symmetric group is a mathematical structure that describes the symmetries of the number line and the regular triangular tesselation of the plane, as well as related higher dimensional objects. It is an infinite extension of the symmetric group, which consists of all permutations (rearrangements) of a finite set. In addition to its geometric description, the affine symmetric group may be defined as the collection of permutations of the integers (..., −2, −1, 0, 1, 2, ...) that are periodic in a certain sense, or in purely algebraic terms as a group with certain generators and relations. These different definitions allow for the extension of many important properties of the finite symmetric group to the infinite setting, and are studied as part of the fields of combinatorics and representation theory.

Female body shape has an apparent influence on mate value as perceived by males. Some researchers have suggested that human male mate preference has evolved to universally favor a specific body shape which can be quantified with a particular value for Waist-Hip Ratio and/or Body Mass Index. Other research has presented evidence that populations of males exhibit differentiated preferences for female body shape. The research literature largely supports the hypothesis that male mate preference for female body shape is variable and dependent upon local resource availability. These conclusions provide insight into the evolutionary processes that have acted to produce adaptive flexibility in human male mate preferences in accordance with the environment.

Contrary to popular misconception, the question in the title is far from simple. It involves sets of numbers on the first level, sets of sets of numbers on the second level, and so on, endlessly. The infinite hierarchy of the levels involved distinguishes the concept of "definable number" from such notions as "natural number", "rational number", "algebraic number", "computable number" etc.

The beak and feather disease virus (BFDV) causes psittacine beak and feather disease, an often chronic and fatal disease in psittacine birds. The virus most commonly infects psittacine birds, but is also capable of infecting non-psittacine bird species in Australasia. The virus induces an immunosuppressive condition with chronic symmetrical irreversible loss of feather, as well as beak and claw deformities eventually leading to death. No specific treatment is currently commercially available for infected birds; however, a combination of quarantine and hygiene control, diagnostic testing and enhancing flock adaptive immunity is recommended to provide the most effective and sustainable control. Recent structural determination of BFDV capsid protein provides insights into the different assemblies that can be formed from one of the smallest known DNA viruses.

E-extension is an approach to agricultural knowledge extension through electronic technologies where online platforms such as web sites, mobile applications and social media are used. Low cost and high effectiveness suggest substantial future possibilities. Nepal's rapid increase in internet usage provides the potential to employ e-extension as a valuable mechanism in the prevailing system of agriculture extension, providing direct advantages to Nepalese farmers. Access to e-extension enables timely updates to newer technologies, information and e-news, with better chances of broad discourse in Nepalese agriculture. This paper aims to document recent initiatives in current e-extension developments in Nepal. Constraints may arise from issues of user-friendliness, affordability and reliability. If promoted with innovation and considerations of actual access, e-extension can have multiple positive impacts on Nepalese agriculture in the near future.

On 13 October 1990, meteoroid EN131090, with an estimated mass of 44 kg, entered the Earth's atmosphere above Czechoslovakia and Poland and, after a few seconds, returned to space. Observations of such events are quite rare; this was the second recorded using scientific astronomical instruments (after the 1972 Great Daylight Fireball) and the first recorded from two distant positions, which enabled the calculation of several of its orbital characteristics. The encounter with Earth significantly changed its orbit and, to a smaller extent, some of its physical properties (mass and structure of its outer layer).

Proteins are biological polymers composed of linear chains of 20 different amino acids. The sequence of amino acids for every protein is unique, and guides its folding into intricate 3-dimensional shapes, known as protein folds. The TIM barrel is one such fold, and is characterized by an interior 8-stranded β-barrel, surrounded and enclosed by 8 α-helices. TIM barrels are named after triose phosphate isomerase (TIM), an enzyme first structurally characterized in 1975, which lends its name to the fold. TIM barrels are prevalent in all forms of life, and across diverse metabolic pathways, with over 10% of all enzymes adopting this fold. The majority of TIM barrels are thought to have evolved from a common ancestor through gene duplication and domain fusion processes. TIM barrels have been created by protein engineers using preexisting half-barrel templates and de novo, without an existing template. This review will discuss the topological, structural, evolutionary, and design characteristics of TIM barrels in detail.

The Grainyhead-like genes are a family of highly conserved transcription factors that are functionally and structurally homologous across a large number of vertebrate and invertebrate species. For an estimated 100 million years or more, this genetic family has been evolving alongside life to fine tune the regulation of epithelial barrier integrity during development, fine-tuning epithelial barrier establishment, maintenance and subsequent homeostasis. The three main orthologues, Grainyhead-like 1, 2 and 3, regulate numerous genetic pathways within different organisms and perform analogous roles between them, ranging from neural tube closure, wound healing, establishment of the craniofacial skeleton and repair of the epithelium. When Grainyhead-like genes are impaired, due to genetic mutations in embryogenesis, it will cause the organism to present with developmental defects that largely affect ectodermal (and sometimes also endodermal) tissues in which they are expressed. These subsequent congenital disorders, including cleft lip and exencephaly, vary greatly in their severity and impact on the quality of life for the affected individual. There is so much more to learn about the function of these genes and the more complex roles of Grainyhead-like genes are yet to be discovered.

Widgiemoolthalite is a rare hydrated nickel(II) carbonate mineral with the chemical formula (Ni,Mg)₅(CO₃)₄(OH)₂·5H₂O. Usually bluish-green in color, it is a brittle mineral formed during the weathering of nickel sulfide. Present on gaspéite surfaces, widgiemoolthalite has a Mohs scale hardness of 3.5 and an unknown though likely disordered crystal structure. Widgiemoolthalite was first discovered in 1992 in Widgiemooltha, Western Australia, which was its only known source as of 2016. It was named in 1993 by the three researchers who first reported its existence, Ernest H. Nickel, Bruce W. Robinson, and William G. Mumme.

Lysenin is a pore-forming toxin present in the coelomic fluid of the earthworm Eisenia fetida. Pore-forming toxins (PFTs) are proteinaceous virulence factors produced by many pathogenic bacteria. Following the general mechanism of action of PFTs, lysenin is secreted as a soluble monomer that binds specifically to the membrane receptor sphingomyelin. After attachment, lysenin forms a 9-copy oligomer (nonamer) prepore on the lipid bilayer before membrane insertion. The biological role of lysenin is still unclear, however the most plausible theory is that it is part of an immune-avoiding mechanism. There are many proposed technological applications proposed for lysenin, and understanding its molecular role in bacterial infection could help in developing different antibiotic strategies to solve the problem of multiple drug resistance in bacteria.

One of the most important parasites of sheep and goats is the nematode Teladorsagia circumcincta. This is common in cool, temperate areas. There is considerable variation among lambs and kids in susceptibility to infection. Much of the variation is genetic and influences the immune response. The parasite induces a type I hypersensitivy response which is responsible for the relative protein deficiency which is characteristic of severely infected animals. There are mechanistic mathematical models which can predict the course of infection. There are a variety of ways to control the infection and a combination of control measures is likely to provide the most effective and sustainable control.

RIG-I (retinoic-acid inducible gene I, also known as DDX58) is the best characterized receptor within the RIG-I like receptor (RLR) family. Together with MDA5 (melanoma differentiation-associated 5) and LGP2 (laboratory of genetics and physiology 2), this family of cytoplasmic pattern recognition receptors (PRRs) are sentinels for intracellular viral RNA that is a product of viral infection. The RLR receptors provide frontline defence against viral infections in most tissues.