551 research outputs found

    What kind of neighbourhoods will people pay more for?

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    This article reviews the evidence on links between value and built form or use in a range of separate categories related to streets: patterns, types and uses. The aim is to examine the evidence around these categories, to help answer the question about how best to inter-weave connectivity and accessibility with everyday life in a way that would appear to work for most residents most of the time and also deliver value to investors and owners in the medium to long term. Some key lessons emerge from the literature review of relationships between place and value that tend to be true most of the time. Ultimately, most people will pay more for a well-connected property away from too much noise, pollution and one waystreets and within walking distance of local amenities

    Maximally-localized Wannier functions for disordered systems: application to amorphous silicon

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    We use the maximally-localized Wannier function method to study bonding properties in amorphous silicon. This study represents, to our knowledge, the first application of the Wannier-function analysis to a disordered system. Our results show that, in the presence of disorder, this method is extremely helpful in providing an unambiguous picture of the bond distribution. In particular, defect configurations can be studied and characterized with a novel degree of accuracy that was not available before.Comment: 4 pages, with 3 PostScript figures embedded. Uses RevTex and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/index.html#nm_as

    Galen, divination, and the status of medicine

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    Galen's stories about his successes in predicting the development of an illness belong to the best-known anecdotes drawn from his writings. Brilliant pieces of self-presentation, they set Galen apart from his peers, who tried to cover up their ignorance by levelling accusations of magic and divination against their superior colleague. These accusations are usually interpreted as very real threats, as Roman law punished illicit magic and divination. Pointing out that Galen sometimes likes to present himself as a mantis and a prophet, others have suggested that the accusations against Galen and his own self-presentation indicate that the border line between medicine and religion was still fluid. Both approaches correctly draw attention to the social reality that the accusations betray: they suggest that Galen belongs to a group of healers of dubious standing that populated the empire and thus show that medicine did not have a monopoly on healing. Yet such a socio-historical approach may not be sufficient. For one thing, both explanations have their limitations. Regarding the former, it can be said that Augustus' prohibition of divination aimed at controlling prediction about the emperor and one can doubt that a widespread clampdown of all forms of divination ever was intended. A possible objection to the second view is that throughout his oeuvre Galen emphasizes his medicine as a rational undertaking, even as a science (episteme). If one takes his self-presentation as a mantis to be more than metaphorical and to indicate the not yet fully crystallized identity of medicine as a separate scientific discipline, then Galen's usual way of understanding his own craft as a science' is in need of explanation. Besides such possible objections, a different set of questions still needs to be asked: why precisely were accusations of practising magic and divination levelled against Galen and why do they recur so frequently in his writings? Why divination and not, say, poisoning

    The rotational excitation of HCN and HNC by He: New insights on the HCN/HNC abundance ratio in molecular clouds

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    Modeling of molecular emission from interstellar clouds requires the calculation of rates for excitation by collisions with the most abundant species. The present paper focuses on the calculation of rate coefficients for rotational excitation of the HCN and HNC molecules in their ground vibrational state in collision with He. The calculations are based on new two-dimensional potential energy surfaces obtained from highly correlated \textit{ab initio} calculations. Calculations of pure rotational (de)excitation cross sections of HCN and HNC by He were performed using the essentially exact close-coupling method. Cross sections for transitions among the 8 first rotational levels of HCN and HNC were calculated for kinetic energies up to 1000 cm1^{-1}. These cross sections were used to determine collisional rate constants for temperatures ranging from 5 K to 100 K. A propensity for even Δj\Delta j transitions is observed in the case of HCN--He collisions whereas a propensity for odd Δj\Delta j transitions is observed in the case of HNC--He collisions. The consequences for astrophysical models are evaluated and it is shown that the use of HCN rate coefficients to interpret HNC observations can lead to significant inaccuracies in the determination of the HNC abundance, in particular in cold dark clouds for which the new HNC rates show that the j=10j=1-0 line of this species will be more easily excited by collisions than HCN. An important result of the new HNC-He rates is that the HNC/HCN abundance ratio derived from observations in cold clouds has to be revised from >>1 to \simeq1, in good agreement with detailed chemical models available in the literature.Comment: 8 figue

    Polymorphisms in SLC44A1 are associated with cognitive improvement in children diagnosed with fetal alcohol spectrum disorder: an exploratory study of oral choline supplementation

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    Background: The essential nutrient choline provides one-carbon units for metabolite synthesis and epigenetic regulation in tissues including brain. Dietary choline intake is often inadequate, and higher intakes are associated with improved cognitive function. Objective: Choline supplements confer cognitive improvement for those diagnosed with fetal alcohol spectrum disorder (FASD), a common set of neurodevelopmental impairments; however, the effect sizes have been modest. In this retrospective analysis, we report that genetic polymorphisms affecting choline utilization are associated with cognitive improvement following choline intervention. Methods: Fifty-two children from the upper midwestern United States and diagnosed with FASD, ages 2-5 y, were randomly assigned to receive choline (500 mg/d; n = 26) or placebo (n = 26) for 9 mo, and were genotyped for 384 choline-related single nucleotide polymorphisms (SNPs). Memory and cognition were assessed at enrollment, study terminus, and at 4-y follow-up for a subset. Results: When stratified by intervention (choline vs. placebo), 14-16 SNPs within the cellular choline transporter gene solute carrier family 44 member 1 (SLC44A1) were significantly associated with performance in an elicited imitation sequential memory task, wherein the effect alleles were associated with the greatest pre-/postintervention improvement. Of these, rs3199966 is a structural variant (S644A) and rs2771040 is a single-nucleotide variant within the 3′ untranslated region of the plasma membrane isoform. An additive genetic model best explained the genotype associations. Lesser associations were observed for cognitive outcome and polymorphisms in flavin monooxygenase-3 (FMO3), methylenetetrahydrofolate dehydrogenase-1 (MTHFD1), fatty acid desaturase-2 (FADS2), and adiponectin receptor 1 (ADIPOR1). Conclusions: These SLC44A1 variants were previously associated with greater vulnerability to choline deficiency. Our data potentially support the use of choline supplements to improve cognitive function in individuals diagnosed with FASD who carry these effect alleles. Although these findings require replication in both retrospective and prospective confirmatory trials, they emphasize the need to incorporate similar genetic analyses of choline-related polymorphisms in other FASD-choline trials, and to test for similar associations within the general FASD population. This trial was registered at www.clinicaltrials.gov as NCT01149538

    Entrance Channel X-HF (X=Cl, Br, and I) Complexes studied by High-Resolution Infrared Laser Spectroscopy in Helium Nanodroplets

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    Rotationally resolved infrared spectra are reported for halogen atom - HF free radical complexes formed in helium nanodroplets. An effusive pyrolysis source is used to dope helium droplets with Cl, Br and I atoms, formed by thermal dissociation of Cl2_2, Br2_2 and I2_2. A single hydrogen fluoride molecule is then added to the droplets, resulting in the formation of the X-HF complexes of interest. Analysis of the resulting spectra confirms that the observed species have 2Π3/2^2\Pi_{3/2} ground electronic states, consistent with the linear hydrogen bound structures predicted from theory. Stark spectra are also reported for these species, from which the permanent electric dipole moments are determined.Comment: 41 pages, 16 figures, 5 table

    Audit market structure, fees and choice in a period of structural change: evidence from the UK – 1998–2003

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    This paper presents evidence on audit market concentration and auditor fee levels in the UK market in the crucial period of structural change following the PricewaterhouseCoopers’ (PwC) merger and encompassing Andersen’s demise (1998–2003). Given the current interest in auditor choice, analysis is also undertaken at the individual audit firm level and by industry sector. There is evidence of significant upward pressure on audit fees since 2001 but only for smaller auditees. Audit fee income for top tier auditors (Big 5/4) did not change significantly while the number of auditees fell significantly, consistent with a move towards larger, less risky, clients. A decomposition analysis of the aggregate Big 5/4 concentration ratio changes over the period identifies the impact of four distinct consumer-based reasons for change: leavers; net joiners; non-par auditor switches; and (only for the audit fees measure) audit fee changes. Andersen’s demise markedly reduced the level of inequality among the top tier firms but PwC retained its position as a ‘dominant firm’. On switching to the new auditor, former Andersen clients experienced an initial audit fee rise broadly in line with inflation, with no evidence of fee premia or discounting. They also reported significantly lower NAS fees, consistent with audit firms and auditees responding to public concerns about perceptions of auditor independence. There is no general evidence of knowledge spillover effects or cross-subsidisation of the audit fee by NAS. The combined findings provide no evidence to indicate that recent structural changes have resulted in anticompetitive pricing; the key concerns remain the lack of audit firm choice and issues concerning the governance and accountability of audit firms

    Mineralization can be an incidental ultrasonographic finding in equine tendons and ligaments

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    Tendon/ligament mineralization is recognized in horses but information regarding its clinical significance is limited. The aims of this observational study were to report the structures most commonly affected by ultrasonographically detectable mineralization and, for these, determine frequency of diagnosis and key clinical features. Cases presented at our hospital in April 1999–April 2013 and September 2014–November 2015 were included: a total of 27 horses (22 retrospective, five prospective). Mineralizations were most common in deep digital flexor tendons (10) and suspensory ligament branches (eight), representing 10% and 7% (estimated), respectively, of horses diagnosed with injuries to these structures during the study. Two deep digital flexor tendon and three suspensory ligament branch cases showed bilateral mineralization. Deep digital flexor tendon mineralization was restricted to the digital flexor tendon sheath, most commonly in the proximal sheath (±sesamoidean canal), and seven of 10 cases involved hindlimbs. Suspensory ligament branch mineralization was visible in the same ultrasound window as the proximal sesamoid bones in 10/11 limbs and six of eight cases involved forelimbs. Previous corticosteroid medication was a feature of one deep digital flexor tendon and one suspensory ligament branch case. Mineralization was associated with lameness in some but not all limbs. Mineralized foci within the deep digital flexor tendon preceded hypoechoic lesion formation in two limbs. Of the cases with deep digital flexor tendon or suspensory ligament branch injury only, one of three and two of three cases, respectively, became sound. Findings indicated that tendon/ligament mineralization can be associated with lameness in some horses, but can also be an incidental finding

    Maximally-localized generalized Wannier functions for composite energy bands

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    We discuss a method for determining the optimally-localized set of generalized Wannier functions associated with a set of Bloch bands in a crystalline solid. By ``generalized Wannier functions'' we mean a set of localized orthonormal orbitals spanning the same space as the specified set of Bloch bands. Although we minimize a functional that represents the total spread sum_n [ _n - _n^2 ] of the Wannier functions in real space, our method proceeds directly from the Bloch functions as represented on a mesh of k-points, and carries out the minimization in a space of unitary matrices U_mn^k describing the rotation among the Bloch bands at each k-point. The method is thus suitable for use in connection with conventional electronic-structure codes. The procedure also returns the total electric polarization as well as the location of each Wannier center. Sample results for Si, GaAs, molecular C2H4, and LiCl will be presented.Comment: 22 pages, two-column style with 4 postscript figures embedded. Uses REVTEX and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/index.html#nm_wan
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