A thermodynamic basis for prebiotic amino acid synthesis and the nature of the first genetic code

Of the twenty amino acids used in proteins, ten were formed in Miller's atmospheric discharge experiments. The two other major proposed sources of prebiotic amino acid synthesis include formation in hydrothermal vents and delivery to Earth via meteorites. We combine observational and experimental data of amino acid frequencies formed by these diverse mechanisms and show that, regardless of the source, these ten early amino acids can be ranked in order of decreasing abundance in prebiotic contexts. This order can be predicted by thermodynamics. The relative abundances of the early amino acids were most likely reflected in the composition of the first proteins at the time the genetic code originated. The remaining amino acids were incorporated into proteins after pathways for their biochemical synthesis evolved. This is consistent with theories of the evolution of the genetic code by stepwise addition of new amino acids. These are hints that key aspects of early biochemistry may be universal.Comment: 16 pages, 2 tables, 4 figures. Accepted for publication in Astrobiolog

A Fundamental Theorem in Linear Programming

Linear Programming is a recent empiral tool made available to the market world. It has already found many important applications and offers exciting opportunities in the future. It can serve as an important management aid to marketing firms. Since linear programming is a fairly new concept in the solution of certain types of problems, a thorough understanding about these properties must be comprehended by the teacher of high school algebra. The primary objective of this paper is to show that given a linear function f defined over a polygonal convex set, its maximum and minimum will occur at the corner points

The Nonpartisan League Leader\u27s Role in the Development of the Nonpartisan League

This study of the Nonpartisan Leagues (NPL) newspaper, Nonpartisan League Leader, examined the interaction between the social, economic, and political environment of North Dakota at the turn of the century and the founding and growth of the NPL Leader. The impact of mass media, specifically newspapers, on farming communities is a forceful tool in shaping social, economic and political processes of those communities. This impact provides a perspective that news is embedded with values, beliefs, and customs of a specific political, economic and cultural system. The evidence presented in the Letter to the Editor column provided the view that news is a social process, and that the views presented in those letters had an impact on the cultural, political and social environment of the community. It is further held that the power over discourse benefits those who own the tools of production and other elite in society

Superconductors with two critical temperatures

We propose a simple model for superconductors endowed with two critical temperatures, corresponding to two second-order phase transitions, in the framework of the Ginzburg-Landau mean-field theory. For very large Cooper pair self-interaction, in addition to the standard condensation occurring in the Ginzburg-Landau theory, we find another phase transition at a lower temperature with a maximum difference of 15% between the two critical temperatures.Comment: revtex, 3 pages, one eps figur

Probing the Higgs mechanism via γγ→W+W−\gamma\gamma\to W^+W^-

We investigate the sensitivity of the reaction $\gamma\gamma\to W^+W^-$ to the Higgs sector based on the complete one-loop corrections in the minimal Standard Model and the gauged non-linear $\sigma$-model. While this sensitivity is very strong for the suppressed cross-section of equally polarized photons and longitudinal W bosons, it is only marginal for the dominant mode of transverse polarizations. The corrections within the $\sigma$-model turn out to be UV-finite in accordance with the absence of \log\MH terms in the Standard Model with a heavy Higgs boson.Comment: 12 pages uuencoded postscrip

Implementing Research and Best Practice for the Development of Mental Health Hubs in the Community

The aim of this review is to improve the quality of the psychiatric built environment and the neighborhoods that surround them so that people are drawn to them by hope and not fear or despair. It is aimed at everyone involved in the planning, the design and the management of psychiatric units, from C&I estates, although hopefully it might prove inspiring to other trusts as well, to architects and all stakeholders involved, including service users

Finite W Algebras and Intermediate Statistics

New realizations of finite W algebras are constructed by relaxing the usual constraint conditions. Then, finite W algebras are recognized in the Heisenberg quantization recently proposed by Leinaas and Myrheim, for a system of two identical particles in d dimensions. As the anyonic parameter is directly associated to the W-algebra involved in the d=1 case, it is natural to consider that the W-algebra framework is well-adapted for a possible generalization of the anyon statistics.Comment: 16 pp., Latex, Preprint ENSLAPP-489/9

Synthesis and Assembly of a Novel Glycan Layer in Myxococcus xanthus Spores

Myxococcus xanthus is a Gram-negative deltaproteobacterium that has evolved the ability to differentiate into metabolically quiescent spores that are resistant to heat and desiccation. An essential feature of the differentiation processes is the assembly of a rigid, cell wall-like spore coat on the surface of the outer membrane. In this study, we characterize the spore coat composition and describe the machinery necessary for secretion of spore coat material and its subsequent assembly into a stress-bearing matrix. Chemical analyses of isolated spore coat material indicate that the spore coat consists primarily of short 1–4- and 1–3-linked GalNAc polymers that lack significant glycosidic branching and may be connected by glycine peptides. We show that 1–4-linked glucose (Glc) is likely a minor component of the spore coat with the majority of the Glc arising from contamination with extracellular polysaccharides, O-antigen, or storage compounds. Neither of these structures is required for the formation of resistant spores. Our analyses indicate the GalNAc/Glc polymer and glycine are exported by the ExoA-I system, a Wzy-like polysaccharide synthesis and export machinery. Arrangement of the capsular-like polysaccharides into a rigid spore coat requires the NfsA–H proteins, members of which reside in either the cytoplasmic membrane (NfsD, -E, and -G) or outer membrane (NfsA, -B, and -C). The Nfs proteins function together to modulate the chain length of the surface polysaccharides, which is apparently necessary for their assembly into a stress-bearing matrix

The Minimal Phantom Sector of the Standard Model: Higgs Phenomenology and Dirac Leptogenesis

We propose the minimal, lepton-number conserving, SU(3)xSU(2)xU(1) gauge-singlet, or phantom, extension of the Standard Model. The extension is natural in the sense that all couplings are of O(1) or forbidden due to a phantom sector global U(1)_D symmetry, and basically imitates the standard Majorana see-saw mechanism. Spontaneous breaking of the U(1)_D symmetry triggers consistent electroweak gauge symmetry breaking only if it occurs at a scale compatible with small Dirac neutrino masses and baryogenesis through Dirac leptogenesis. Dirac leptogenesis proceeds through the usual out-of-equilibrium decay scenario, leading to left and right-handed neutrino asymmetries that do not fully equilibrate after they are produced. The model contains two physical Higgs bosons and a massless Goldstone boson. The existence of the Goldstone boson suppresses the Higgs to bb branching ratio and instead the Higgs bosons will mainly decay to invisible Goldstone and/or to visible vector boson pairs. In a representative scenario, we estimate that with 30 fb^-1 integrated luminosity, the LHC could discover this invisibly decaying Higgs, with mass ~120 GeV. At the same time a significantly heavier, partner Higgs boson with mass ~210 GeV could be found through its vector boson decays. Electroweak constraints as well as astrophysical and cosmological implications are analysed and discussed.Comment: 21 pages, 4 figures. Corrected typos and added references. To appear in JHE