Affine symmetric group

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 additition 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.

Evolved human male preferences for female body shape

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.

A broad introduction to RNA-Seq

RNA-Seq, named as an abbreviation of "RNA sequencing" and sometimes spelled RNA-seq, RNAseq, or RNASeq, uses next-generation sequencing (NGS) to reveal the presence and quantity of ribonucleic acid (RNA) in a biological sample at a given moment.[1][2] RNA-Seq is used to analyze the continuously changing cellular transcriptome (Figure 1). Specifically, RNA-Seq facilitates the ability to look at alternative gene spliced transcripts, post-transcriptional modifications, gene fusion, mutations/single nucleotide polymorphisms (SNPs) and changes in gene expression over time, or differences in gene expression in different groups or treatments.[3] In addition to messenger RNA (mRNA) transcripts, RNA-Seq can look at different populations of RNA to include total RNA, small RNA, such as microRNA (miRNA), transfer RNA (tRNA), and ribosomal profiling.[4] RNA-Seq can also be used to determine exon/intron boundaries and verify or amend previously annotated 5' and 3' gene boundaries. Recent advances in RNA-Seq include single cell sequencing, in situ sequencing of fixed tissue, and native RNA molecule sequencing with single-molecule real-time sequencing.[5] Prior to RNA-Seq, gene expression studies were done with hybridization-based microarrays. Issues with microarrays include cross-hybridization artifacts, poor quantification of lowly and highly expressed genes, and needing to know the sequence a priori.[6] Because of these technical issues, transcriptomics transitioned to sequencing-based methods. These progressed from Sanger sequencing of Expressed Sequence Tag libraries, to chemical tag-based methods (e.g., serial analysis of gene expression), and finally to the current technology, next-gen sequencing of complementary DNA ( cDNA), notably RNA-Seq.

“Collect, acquire, analyze, report, and disseminate statistical data related to the science and engineering enterprise…”: The National Center for Science and Engineering Statistics

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.

Structural Model of Bacteriophage T4

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).[1] 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,[2] and complexes of multiple proteins in the 1990s.[3] However, it has not yet been possible to structurally characterise the complete phage in atomic detail (though some have begun to come closer)[4] with multiple overall schematic models published.[5] 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.

Arabinogalactan-proteins

Arabinogalactan-proteins (AGPs) are highly glycosylated proteins (glycoproteins) found in the cell walls of plants. AGPs account for only a small portion of the cell wall, usually no more than 1% of dry mass of the primary wall. AGPs are members of the hydroxyproline-rich glycoprotein (HRGP) superfamily that represent a large and diverse group of glycosylated wall proteins. AGPs have attracted considerable attention due to their highly complex structures and potential roles in signalling. In addition, they have industrial and health applications due to their chemical/physical properties (water-holding, adhesion and emulsification). Glycosylation can account for more than 90% of the total mass. AGPs have been reported in a wide range of higher plants in seeds, roots, stems, leaves and inflorescences. They have also been reported in secretions of cell culture medium of root, leaf, endosperm and embryo tissues, and some exudate producing cell types such as stylar canal cells are capable of producing lavish amounts of AGPs.