9,461 research outputs found

    Do I Dare Disturb the Universe?

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    This memoir investigates the roots of my core anxiety, the incessant but impossible ability to achieve perfection. It is framed by my experience getting a second tattoo, which is a line from T.S. Eliot\u27s modernist poem, The Love Song of J. Alfred Prufrock, and ties together both my internal struggle and my affinity for physical pain. This memoir draws a line between the past and the present, seeking to find a connection between struggling with anxiety and engaging in self-mutilation as a source of relief

    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

    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

    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

    A study of wing body blending for an advanced supersonic transport

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    Increases in supersonic cruise lift drag ratio were sought at Mach numbers 2.2 and 2.7 using wing body planform and thickness blending. Constrained twist and camber optimization was performed in the presence of nacelles. Wing and fuselage thickness distributions were optimized for either minimum volume wave drag or minimum total pressure wave drag. The zero leading edge suction lift drag ratios were determined for three wing planforms. The magnitude of the effect of leading edge suction on attainable lift drag ratio was defined on one planform and estimation of available leading edge suction was made

    Improving Student Attendance in Two Rural Mississippi Elementary Schools

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    The purpose of this applied study was to solve the problem of low student attendance for two elementary schools in southwest Mississippi by reviewing interventions designed to improve average daily attendance among elementary students. This study sought to review previous interventions and determine which initiatives worked to improve student attendance using qualitative and quantitative methods. Qualitative methods such as interviews and document analysis were conducted with staff and administrators who work within the school district, ensuring attendance regulations are being met. Their responses, along with a review of related literature, provided insights into recent initiatives undertaken to address attendance issues. Quantitative methods, specifically a teacher survey, was designed based on themes resulting from the literature review. This feedback helped to place the problem of attendance in perspective and was used as a baseline measure to determine if previous initiatives had any impact on student attendance rates. A search of the literature indicated that numerous studies address the causes of student absences, absenteeism, and truancy, yet there is limited data that addressed what schools are or are not doing to combat the increasing problem of excessive absences in the elementary grades. Data gathered from semi-structured interviews, surveys, and document analysis provided a basis for remedying this problem. Using indicators obtained from research data may provide school districts with a starting point in which to develop or improve existing strategies for improving attendance at the elementary grades

    An assessment of scup (Stenotomus chrysops) and black sea bass (Centropristas striata) discards in the directed otter trawl fisheries in the Mid-Atlantic Bight

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    This study was undertaken to re-assess the level of scup (Stenotomus chrysops) discards by weight and to evaluate the effect of various codend mesh sizes on the level of scup discards in the winter-trawl scup fishery. Scup discards were high in directed scup tows regardless of codend mesh — typically one to five times the weight of landings. The weight of scup discards in the present study did not differ significantly from that recorded in scup-targeted tows in the NMFS observer database. Most discards were required as such by the 22.86 cm TL (total length) fish-size limit for catches. Mesh sizes ≤12.7 cm, including the current legal mesh size (11.43 cm) did not adequately filter out scup smaller than 22.86 cm. The median length of scup discards was about 19.83 cm TL. Lowering the legal size for scup from 22.86 to 19.83 cm TL would greatly reduce discard mortality. Scup discards were a small fraction (0.4%) of black sea bass (Centropristis striata) landings in blacksea-bass−targeted tows. The black sea bass fishery is currently regulated under the small-mesh fishery gearrestricted area plan in which fishing is prohibited in some areas to reduce scup mortality. Our study found no evidence to support the efficacy of this management approach. The expectations that discarding would increase disproportionately as the trip limit (limit [in kilograms] on catch for a species) was reached towards the end of the trip and that discards would increase when the trip limit was reduced from 4536 kg to 454 kg at the end of the directed fishing season were not supported. Trip limits did not significantly affect discard mortality

    Disaster Preparedness Education and Resource Needs for Pregnant and Post-Partum Families

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    Hurricane Katrina in 2005 heightened awareness of the need to educate vulnerable populations on disaster preparedness. However, little has been written specifically on the preparedness needs of the pregnant and post-partum families. Only one article explores disaster preparedness education for this population. To fill this gap. An interprofessional sample (n=115) rated the relevance of the educational topics and birthing kit items proposed by the panel from the previous Delphi study. The education topics were reduced to four themes that explained 66.80% of the variance and the birthing kit items were reduced to six themes that explained 70.99% of the variance
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