45,334 research outputs found
From inanimate matter to living systems
Since the early part of this century, the Genesis account of the origin and evolution of life has been explained as an extrapolation of astronomical and geochemical processes. The essence of the answer to date is a protoreproductive protocell of much biochemical and cytophysical competance. The processes of its origin, molecular ordering, and its functions are described. A crucial understanding is that of the nonrandomness of evolutionary processes at all stages (with perhaps a minor statistical component). In this way, evolution conflicts with statistical randomness; the latter is a favorite assumption of both scientific and creationistic critics of the proteinoid theory. The principle contribution of the proteinoid theory to the understanding of general biology is to particularize the view that evolutionary direction is rooted in the shapes of molecules, in stereochemistry. After molecules of the right kind first assembled to protocells, life in its various stages of evolution was an inevitable consequence. It is molecules that continue to assemble as part of living process and, in the role of enzymes, continue to direct life cycle of the cell
<investigations in space-related biology, including molecular evolution and relevant aspects of the extra-terrestrial environment< semiannual status report, 1 jun. - 30 nov. 1964
Investigations in space related biology, molecular evolution, and extraterrestrial environmen
Condensation of Cytidylic Acid in the Presence of Polyphosphoric Acid
Condensation of cytidylic acid in presence of polyphosphoric aci
The preparation of citrulline by hydrolysis of arginine
The theoretical hydrolysis of arginine to citrulline in vitro has been accomplished and discussed. The details for rapidly and conveniently preparing a 65 gm. quantity of citrulline with the aid of this single reaction have been presented
Molecular bases for unity and diversity in organic evolution
The origin of biological information has been ascribed at various times to DNA, RNA, or protein. The origin of nucleic acids without the action of prior informed protein has not been supported by plausible experiments, although such possibilities have been examined. The behavior of thermal proteins and of the microspheres selfassembled therefrom explain the origin of the first cells, the first membrane, the first reproduction cycle, ancient metabolism including ATP-aided synthesis of peptides and polynucleotides, growth, bioelectricity, and polybiofunctionality in general
Fast magnetic reconnection in laser-produced plasma bubbles
Recent experiments have observed magnetic reconnection in
high-energy-density, laser-produced plasma bubbles, with reconnection rates
observed to be much higher than can be explained by classical theory. Based on
fully kinetic particle simulations we find that fast reconnection in these
strongly driven systems can be explained by magnetic flux pile-up at the
shoulder of the current sheet and subsequent fast reconnection via two-fluid,
collisionless mechanisms. In the strong drive regime with two-fluid effects, we
find that the ultimate reconnection time is insensitive to the nominal system
Alfven time.Comment: 5 pages, 4 figures, accepted by Phys. Rev. Let
Consumer Perception of Sorghum Variety Attributes in the Lake Zone Tanzania
Many sorghum varieties have been developed by research institutes in an effort to address food security problems in the semi-arid areas of Tanzania. Although sorghum is better adapted to drier areas than maize, farmer adoption rates for sorghum varieties are always lower than that of maize. In addition, maize based food is more acceptable to urban consumers than sorghum based food. In this study consumer evaluated quality attributes of sorghum ugali based on different varieties in order to determine marketing potential relating to the different improved sorghum varieties. A total of 231 consumers, randomly selected from urban and rural areas participated in a food panel to evaluate ugali prepared from five sorghum varieties (three improved, two local). Conjoint analysis was used to determine consumer perceptions of the variety attributes, while a logistic model was applied to determine preference ranking of different varieties. The results indicated that the color and taste of sorghum ugali were the most important criteria used by consumers to evaluate the quality ugali. The study results indicated that sorghum ugali with white/khaki color and the majority of panel participants preferred neutral or slightly sweet taste. Consumers from rural and urban areas accepted two improved varieties; only consumers from rural areas accepted the remaining variety.Adoption, consumer perception, conjoint analysis, sorghum varieties, Tanzania, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,
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Materials for Biomedical Applications
This paper discusses two ceramic material systems for selective laser sintering (SLS) that are
being developed for biomedical applications for use in repair of bone defects. SLS is the
preferred method of fabricating ceramic implants that exhibit well defined porous
microstructures. Implants fabricated in this. manner have proven effective in-vivo showing
excellent biocompatibility as well as considerable osseous integration and remodeling of the
imp'ant materialMechanical Engineerin
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