6,420 research outputs found

    Experiments on the origin of molecular chirality by parity non-conservation during beta-decay

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    Experiments are described to test a theory for the origin of optical activity wherein the longitudinally polarized electrons resulting from parity violation during radioactive beta decay, and their resulting circularly polarized Bremsstrahlung, might interact asymmetrically with organic matter to yield optically active products. Experiments involve subjecting a number of racemic and optically active amino acid samples to irradiation in a 61700 Ci90SR-90Y beta radiation source for a period of 1.34 years, then examining them for any asymmetric effects by means of optical rotatory dispersion and analytical gas chromatography. In the cases of D,L-leucine, norleucine, norvaline and proline as solids, of D,L-leucine in solution and of D,L-tyrosine in alkaline solution no optical rotation was observed during CRD measurements in the 250-630 nm spectral region. While slight differences were noted in the percent radiolysis of solid D- (12.7%) and L-leucine (16.2%) as determined by GC, no enrichment of either enantiomer was found

    Phosphorus in land-water systems

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    Analyses were made to obtain information on distribution of different forms of phosphate in different environmental media, including soils, eroding material, and bottom sediment. Major emphasis was placed on determining several forms of inorganic phosphate in each media. Results show that eroding material can transport significant quantities of phosphates from soils

    Total Chiral Symmetry Breaking during Crystallization: Who needs a "Mother Crystal"?

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    Processes that can produce states of broken chiral symmetry are of particular interest to physics, chemistry and biology. Chiral symmetry breaking during crystallization of sodium chlorate occurs via the production of secondary crystals of the same handedness from a single "mother crystal" that seeds the solution. Here we report that a large and "symmetric" population of D- and L-crystals moves into complete chiral purity disappearing one of the enantiomers. This result shows: (i) a new symmetry breaking process incompatible with the hypothesis of a single "mother crystal"; (ii) that complete symmetry breaking and chiral purity can be achieved from an initial system with both enantiomers. These findings demand a new explanation to the process of total symmetry breaking in crystallization without the intervention of a "mother crystal" and open the debate on this fascinating phenomenon. We present arguments to show that our experimental data can been explained with a new model of "complete chiral purity induced by nonlinear autocatalysis and recycling".Comment: 5 pages, 4 figures, Added reference

    Aerodynamic preliminary analysis system 2. Part 1: Theory

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    An aerodynamic analysis system based on potential theory at subsonic and/or supersonic speeds and impact type finite element solutions at hypersonic conditions is described. Three dimensional configurations having multiple nonplanar surfaces of arbitrary planform and bodies of noncircular contour may be analyzed. Static, rotary, and control longitudinal and lateral directional characteristics may be generated. The analysis was implemented on a time sharing system in conjunction with an input tablet digitizer and an interactive graphics input/output display and editing terminal to maximize its responsiveness to the preliminary analysis problem. The program provides an efficient analysis for systematically performing various aerodynamic configuration tradeoff and evaluation studies

    The Fast Wandering of Slow Birds

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    I study a single "slow" bird moving with a flock of birds of a different, and faster (or slower) species. I find that every "species" of flocker has a characteristic speed γv0\gamma\ne v_0, where v0v_0 is the mean speed of the flock, such that, if the speed vsv_s of the "slow" bird equals γ\gamma, it will randomly wander transverse to the mean direction of flock motion far faster than the other birds will: its mean-squared transverse displacement will grow in d=2d=2 with time tt like t5/3t^{5/3}, in contrast to t4/3t^{4/3} for the other birds. In d=3d=3, the slow bird's mean squared transverse displacement grows like t5/4t^{5/4}, in contrast to tt for the other birds. If vsγv_s\neq \gamma, the mean-squared displacement of the "slow" bird crosses over from t5/2t^{5/2} to t4/3t^{4/3} scaling in d=2d=2, and from t5/4t^{5/4} to tt scaling in d=3d=3, at a time tct_c that scales according to tcvsγ2t_c \propto|v_s-\gamma|^{-2}.Comment: 10 pages; 5 pages of which did not appear in earlier versions, but were added in response to referee's suggestion

    Aircraft energy efficiency laminar flow control wing design study

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    An engineering design study was performed in which laminar flow control (LFC) was integrated into the wing of a commercial passenger transport aircraft. A baseline aircraft configuration was selected and the wing geometry was defined. The LFC system, with suction slots, ducting, and suction pumps was integrated with the wing structure. The use of standard aluminum technology and advanced superplastic formed diffusion bonded titanium technology was evaluated. The results of the design study show that the LFC system can be integrated with the wing structure to provide a structurally and aerodynamically efficient wing for a commercial transport aircraft

    Ethical and Legal Knowledge, Cognitive Complexity, and Moral Reasoning in Counseling Students

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    Accrediting, credentialing, and counseling association bodies require counselors to possess ethical and legal knowledge and an understanding of applying ethical and legal standards to effectively serve clients. Prior to the creation of an ethical and legal knowledge instrument, scholars had theorized a relationship among ethical and legal knowledge, cognitive development, and ethical decision-making in counseling. With the creation of a new instrument for ethical and legal knowledge, ethical and legal knowledge could be assessed with extensively used constructs such as moral reasoning for ethical decision-making and cognitive complexity for cognitive development. This study investigated ethical and legal knowledge and cognitive complexity as predictors of moral reasoning. From eight institutions, 65 counseling students completed the three instruments through an online survey. Higher ethical and legal knowledge was a predictor of higher levels of moral reasoning in counseling students. Inferences for counselor educators, counselors, and future research were discussed

    The impact of space and space-related activities on a local economy. a case study of boulder, colorado. part ii- the income-product accounts

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    Total impact of space and space related activities on local economy of Boulder, Colorado - income-product account

    A Reanalysis of the Hydrodynamic Theory of Fluid, Polar-Ordered Flocks

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    I reanalyze the hydrodynamic theory of fluid, polar ordered flocks. I find new linear terms in the hydrodynamic equations which slightly modify the anisotropy, but not the scaling, of the damping of sound modes. I also find that the nonlinearities allowed {\it in equilibrium} do not stabilize long ranged order in spatial dimensions d=2d=2; in accord with the Mermin-Wagner theorem. Nonequilibrium nonlinearities {\it do} stabilize long ranged order in d=2d=2, as argued by earlier work. Some of these were missed by earlier work; it is unclear whether or not they change the scaling exponents in d=2d=2.Comment: 6 pages, no figures. arXiv admin note: text overlap with arXiv:0909.195
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