5,339 research outputs found

    The future of human nature and social progress : a case for optimism in an age of despair

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    When discussing the topic of social progress and possible futures, a common argument is that so-called "utopian" ideas are implausible due to the limitations of human nature. This paper attempts to explain the faults in that argument by pointing out common flaws in the typical understanding of "human nature" and the history and direction of social progress. The belief that human nature is universal and constant is countered by evidence that human psychology and behavior are largely culturally formed and change across time and geography due to macro-cultural factors. Furthermore, social progress has continually advanced throughout history, despite modern skepticism, and maintains a positive trajectory to this day. With these two arguments, it can be concluded that, as societies become more pro-social, human nature itself will follow suit, changing the limitations of human nature and thus the potentials for social progress.Honors CollegeThesis (B.?

    Time outdoors and the prevention of myopia

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    Recent epidemiological evidence suggests that children who spend more time outdoors are less likely to be, or to become myopic, irrespective of how much near work they do, or whether their parents are myopic. It is currently uncertain if time outdoors also blocks progression of myopia. It has been suggested that the mechanism of the protective effect of time outdoors involves light-stimulated release of dopamine from the retina, since increased dopamine release appears to inhibit increased axial elongation, which is the structural basis of myopia. This hypothesis has been supported by animal experiments which have replicated the protective effects of bright light against the development of myopia under laboratory conditions, and have shown that the effect is, at least in part, mediated by dopamine, since the D2-dopamine antagonist spiperone reduces the protective effect. There are some inconsistencies in the evidence, most notably the limited inhibition by bright light under laboratory conditions of lens-induced myopia in monkeys, but other proposed mechanisms possibly associated with time outdoors such as relaxed accommodation, more uniform dioptric space, increased pupil constriction, exposure to UV light, changes in the spectral composition of visible light, or increased physical activity have little epidemiological or experimental support. Irrespective of the mechanisms involved, clinical trials are now underway to reduce the development of myopia in children by increasing the amount of time they spend outdoors. These trials would benefit from more precise definition of thresholds for protection in terms of intensity and duration of light exposures. These can be investigated in animal experiments in appropriate models, and can also be determined in epidemiological studies, although more precise measurement of exposures than those currently provided by questionnaires is desirable

    Rapid Separable Analysis of Higher Order Correlators in Large Scale Structure

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    We present an efficient separable approach to the estimation and reconstruction of the bispectrum and the trispectrum from observational (or simulated) large scale structure data. This is developed from general CMB (poly-)spectra methods which exploit the fact that the bispectrum and trispectrum in the literature can be represented by a separable mode expansion which converges rapidly (with nmax=O(30)n_\textrm{max}={\cal{O}}(30) terms). With an effective grid resolution lmaxl_\textrm{max} (number of particles/grid points N=lmax3N=l_\textrm{max}^3), we present a bispectrum estimator which requires only O(nmax×lmax3){\cal O}(n_\textrm{max} \times l_\textrm{max}^3) operations, along with a corresponding method for direct bispectrum reconstruction. This method is extended to the trispectrum revealing an estimator which requires only O(nmax4/3×lmax3){\cal O}(n_\textrm{max}^{4/3} \times l_\textrm{max}^3) operations. The complexity in calculating the trispectrum in this method is now involved in the original decomposition and orthogonalisation process which need only be performed once for each model. However, for non-diagonal trispectra these processes present little extra difficulty and may be performed in O(lmax4){\cal O}(l_\textrm{max}^4) operations. A discussion of how the methodology may be applied to the quadspectrum is also given. An efficient algorithm for the generation of arbitrary nonGaussian initial conditions for use in N-body codes using this separable approach is described. This prescription allows for the production of nonGaussian initial conditions for arbitrary bispectra and trispectra. A brief outline of the key issues involved in parameter estimation, particularly in the non-linear regime, is also given

    How Barred is the NIR Nearby Universe? An analysis using 2MASS

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    We determine a firm lower limit to the bar fraction of 0.58 in the nearby universe using J+H+Ks-band images for 134 spirals from 2MASS. With a mean deprojected semi-major axis of 5.1 kpc, and a mean deprojected ellipticity of 0.45 this local bar sample lays the ground work for studies on bar formation and evolution at high redshift.Comment: In the proceedings "Penetrating Bars through Masks of Cosmic Dust: The Hubble Tuning Fork strikes a New Note

    The suppression of superconductivity in MgCNi3 by Ni-site doping

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    The effects of partial substitution of Cu and Co for Ni in the intermetallic perovskite superconductor MgCNi3 are reported. Calculation of the expected electronic density of states suggests that electron (Cu) and hole (Co) doping should have different effects. For MgCNi3-xCux, solubility of Cu is limited to approximately 3% (x = 0.1), and Tc decreases systematically from 7K to 6K. For MgCNi3-xCox, solubility of Co is much more extensive, but bulk superconductivity disappears for Co doping of 1% (x = 0.03). No signature of long range magnetic ordering is observed in the magnetic susceptibility of the Co doped material.Comment: submitted, Solid State Communication

    Emerging Infections and Pregnancy

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    Immunologic changes of pregnancy may increase susceptibility to certain intracellular pathogens
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