25,019 research outputs found

    Molecular bases for unity and diversity in organic evolution

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    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

    Three Dimensional Color Pictures by Projection

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    With the production of a cheap polarizing material stereoscopic projection of color pictures is a reality. The technique of projection by both the transmission and reflection methods will be demonstrated

    Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law

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    In the interaction of high-power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. Such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields.We show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection rate is dictated by heat flows rather than Alfv\`enic flows. We find that this mechanism is only relevant in a high β\beta plasma. However, the Hall parameter ωcτei\omega_c \tau_{ei} can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system

    Amino acids precursors in lunar finds

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    The consistent pattern is discussed of amino acids found in lunar dust from Apollo missions. The evidence indicates that compounds yielding amino acids were implanted into the surface of the moon by the solar wind, and the kind and amounts of amino acids found on the moon are closely similar to those found in meteorites. It is concluded that there is a common cosmochemical pattern for the moom and meteorites, and this offers evidence of a common course of cosmochemical reactions for carbon

    Machine Assisted Proof of ARMv7 Instruction Level Isolation Properties

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    In this paper, we formally verify security properties of the ARMv7 Instruction Set Architecture (ISA) for user mode executions. To obtain guarantees that arbitrary (and unknown) user processes are able to run isolated from privileged software and other user processes, instruction level noninterference and integrity properties are provided, along with proofs that transitions to privileged modes can only occur in a controlled manner. This work establishes a main requirement for operating system and hypervisor verification, as demonstrated for the PROSPER separation kernel. The proof is performed in the HOL4 theorem prover, taking the Cambridge model of ARM as basis. To this end, a proof tool has been developed, which assists the verification of relational state predicates semi-automatically

    Potentialities of proteinoids for nutritional investigation

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    Simultaneous synthesis of amino acids and proteinoid production for nutritional investigatio

    Effect of Piezo Electric Oscillations on X-Ray Patterns of Quartz

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    Experiments have been made to determine the amplitude of vibration of the atoms in a quartz lattice due to piezo electric oscillations. A series of Laue X-ray patterns have been made of quartz plates cut at various angles to the electric axes. Very marked intensity differences are apparent between the patterns made with the plates oscillating and not oscillating

    Application of a Finite Element Model to a Cold-formed Steel C-section with a Bearing Stiffener

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    Described in this paper is the application of a finite element model to a cold-formed steel C-section with a bearing stiffener installed between its flanges. This model has been used to determine both the web crippling capacity of the joist, and the forces that develop in the fasteners connecting the bearing stiffener to the joist. The finite element model was also used to carry out parametric studies of the stiffened joist assembly to determine the impact on the web crippling capacity and the fastener forces caused by variations in the assembly. Based on the results of these finite element studies, combined with available experimental work, a design expression has been proposed that can calculate the web crippling capacity of a cold formed steel C-section joist that has a bearing stiffener installed between the joist flanges. A second design expression has been proposed for predicting the forces in the fasteners that connect the joist to the stiffener. Predictions of both the web crippling capacity and the fastener forces are necessary for determining the ultimate strength of the stiffened joist assembly

    High-severity wildfire leads to multi-decadal impacts on soil biogeochemistry in mixed-conifer forests.

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    During the past century, systematic wildfire suppression has decreased fire frequency and increased fire severity in the western United States of America. While this has resulted in large ecological changes aboveground such as altered tree species composition and increased forest density, little is known about the long-term, belowground implications of altered, ecologically novel, fire regimes, especially on soil biological processes. To better understand the long-term implications of ecologically novel, high-severity fire, we used a 44-yr high-severity fire chronosequence in the Sierra Nevada where forests were historically adapted to frequent, low-severity fire, but were fire suppressed for at least 70 yr. High-severity fire in the Sierra Nevada resulted in a long-term (44 +yr) decrease (>50%, P < 0.05) in soil extracellular enzyme activities, basal microbial respiration (56-72%, P < 0.05), and organic carbon (>50%, P < 0.05) in the upper 5 cm compared to sites that had not been burned for at least 115 yr. However, nitrogen (N) processes were only affected in the most recent fire site (4 yr post-fire). Net nitrification increased by over 600% in the most recent fire site (P < 0.001), but returned to similar levels as the unburned control in the 13-yr site. Contrary to previous studies, we did not find a consistent effect of plant cover type on soil biogeochemical processes in mid-successional (10-50 yr) forest soils. Rather, the 44-yr reduction in soil organic carbon (C) quantity correlated positively with dampened C cycling processes. Our results show the drastic and long-term implication of ecologically novel, high-severity fire on soil biogeochemistry and underscore the need for long-term fire ecological experiments
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