2,351 research outputs found

    The Beilinson Equivalence for Differential Operators and Lie Algebroids

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    Let D be the ring of differential operators on a smooth irreducible affine variety X over the complex numbers; or, more generally, the enveloping algebra of any locally free Lie algebroid on X. The category of finitely-generated graded modules of the Rees algebra D has a natural quotient category qgr(D) which imitates the category of modules on Proj of a graded commutative ring. We show that the derived category D^b(qgr(D)) is equivalent to the derived category of finitely-generated modules of a sheaf of algebras E on X which is coherent over X. This generalizes the usual Beilinson equivalence for projective space, and also the Beilinson equivalence for differential operators on a smooth curve used by Ben-Zvi and Nevins to describe the moduli space of left ideals in D

    Using geographic profiling to locate elusive nocturnal animals: A case study with spectral tarsiers

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    © 2015 The Zoological Society of London. Estimates of biodiversity, population size, population density and habitat use have important implications for management of both species and habitats, yet are based on census data that can be extremely difficult to collect. Traditional assessment techniques are often limited by time and money and by the difficulties of working in certain habitats, and species become more difficult to find as population size decreases. Particular difficulties arise when studying elusive species with cryptic behaviours. Here, we show how geographic profiling (GP) - a statistical tool originally developed in criminology to prioritize large lists of suspects in cases of serial crime - can be used to address these problems. We ask whether GP can be used to locate sleeping sites of spectral tarsiers Tarsius tarsier in Sulawesi, Southeast Asia, using as input the positions at which tarsier vocalizations were recorded in the field. This novel application of GP is potentially of value as tarsiers are cryptic and nocturnal and can easily be overlooked in habitat assessments (e.g. in dense rainforest). Our results show that GP provides a useful tool for locating sleeping sites of this species, and indeed analysis of a preliminary dataset during field work strongly suggested the presence of a sleeping tree at a previously unknown location; two sleeping trees were subsequently found within 5m of the predicted site. We believe that GP can be successfully applied to locating the nests, dens or roosts of elusive animals such as tarsiers, potentially improving estimates of population size with important implications for management of both species and habitats.We thank Operation Wallacea for supporting S.C.F. in thisproject and for providing logistical support for the fieldwork,and Aidan Kelsey for invaluable assistance in the field. Wethank the Indonesian Institute of Sciences (LIPI) andKementerian Riset dan Teknologi Republik Indonesia(RISTEK) for providing permission to undertake the work(RISTEK permit no. 211/SIP/FRP/SM/VI/2013, and BalaiKonservasi Sumber Daya Alam (BKSDA) for theirassistance

    The theoretical molecular weight of NaYF ₄ :RE upconversion nanoparticles

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    Upconversion nanoparticles (UCNPs) are utilized extensively for biomedical imaging, sensing, and therapeutic applications, yet the molecular weight of UCNPs has not previously been reported. Herein, we present a theory based upon the crystal structure of UCNPs to estimate the molecular weight of UCNPs: enabling insight into UCNP molecular weight for the first time. We estimate the theoretical molecular weight of various UCNPs reported in the literature, predicting that spherical NaYF4 UCNPs ~ 10 nm in diameter will be ~1 MDa (i.e. 106 g/mol), whereas UCNPs ~ 45 nm in diameter will be ~100 MDa (i.e. 108 g/mol). We also predict that hexagonal crystal phase UCNPs will be of greater molecular weight than cubic crystal phase UCNPs. Additionally we find that a Gaussian UCNP diameter distribution will correspond to a lognormal UCNP molecular weight distribution. Our approach could potentially be generalised to predict the molecular weight of other arbitrary crystalline nanoparticles: as such, we provide stand-alone graphic user interfaces to calculate the molecular weight both UCNPs and arbitrary crystalline nanoparticles. We expect knowledge of UCNP molecular weight to be of wide utility in biomedical applications where reporting UCNP quantity in absolute numbers or molarity will be beneficial for inter-study comparison and repeatability

    Evidence of Titan's Climate History from Evaporite Distribution

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    Water-ice-poor, 5-μ\mum-bright material on Saturn's moon Titan has previously been geomorphologically identified as evaporitic. Here we present a global distribution of the occurrences of the 5-μ\mum-bright spectral unit, identified with Cassini's Visual Infrared Mapping Spectrometer (VIMS) and examined with RADAR when possible. We explore the possibility that each of these occurrences are evaporite deposits. The 5-μ\mum-bright material covers 1\% of Titan's surface and is not limited to the poles (the only regions with extensive, long-lived surface liquid). We find the greatest areal concentration to be in the equatorial basins Tui Regio and Hotei Regio. Our interpretations, based on the correlation between 5-μ\mum-bright material and lakebeds, imply that there was enough liquid present at some time to create the observed 5-μ\mum-bright material. We address the climate implications surrounding a lack of evaporitic material at the south polar basins: if the south pole basins were filled at some point in the past, then where is the evaporite

    Selective expression of a VHIV subfamily of immunoglobulin genes in human CD5+ B lymphocytes from cord blood.

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    Human B lymphocytes expressing the CD5 surface antigen (CD5+ B cells) constitute a subset capable of producing polyspecific antibodies recognizing a variety of self antigens. The repertoire of antibodies produced by CD5+ and CD5- B cells is different. However, it is not yet established whether this distribution is reflected in different immunoglobulin variable region gene (IgV) use. Rearrangement of heavy chain IgV (IgVH) genes represents one of the first identifiable stages in the maturation of B cells, and occurs in a developmentally ordered fashion. The repertoire of IgVH gene expression is highly restricted during fetal life but diversifies progressively after birth. A high frequency of VH gene use from the relatively small VHIV gene family has previously been demonstrated in human fetal liver B cells. In the present study, 102 B cell lines established by Epstein-Barr Virus-transformation of separated CD5+ and CD5- cord blood B cells, were examined for the frequency of IgV expression using monoclonal antibodies to cross-reactive idiotypes (CRI). The results demonstrate a relatively high frequency of VHIV gene use (30%) in B cells from cord blood. Furthermore, two mutually exclusive CRI associated with distinct subgroups of the VHIV family are segregated in their association with either subset of B cells. One CRI is exclusively expressed in lines established from CD5+ B cells while the other is associated with lines established from CD5- B cells

    An assessment of the aversive nature of an animal management procedure (clipping) using behavioral and physiological measures

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    Animal management often involves procedures that, while unlikely to cause physical pain, still cause aversive responses. The domestic horse ( Equus caballus ) regularly has excessive hair clipped off to facilitate its use as a riding/driving animal and this procedure causes adverse behavioral responses in some animals. The aim of this study was to compare behavioral and physiological measures to assess the aversive effect of this procedure. Ten horses were selected on the basis of being either compliant (C: n = 5) or non-compliant (NC: n = 5) during this procedure. The horses were subjected to a sham clipping procedure (SC: where the blades had been removed from the clippers) for a period of ten minutes. Measures were taken pre, during and post SC (−10 min to +30 min) and mean values calculated for ALL horses and for C and NC separately. Behavioral activity was scored (scale 1-5) by twenty students from video footage in (phase/group-blind scoring). Heart rate (HR), salivary cortisol and eye temperature were monitored throughout the procedure. The NC horses were found to be significantly more behaviorally active/less relaxed throughout the trial than C horses(p b 0.05) with the greatest difference occurring during the SC procedure (p b 0.01). NC horses were more active/less relaxed during, compared with pre or post SC (p b 0.05), but showed no behavioral difference pre and post SC. HR of the NC horses was higher than that of the C horses throughout the trial but only significantly so after 10 min of SC (p b 0.01). ALL horses showed significant increase in HR between +5 and +10 min into the procedure (p b 0.05). There was a significant increase in salivary cortisol concentration in ALL horses post procedure (p b 0.01) with levels peaking at 20 minute post SC. No significant differences in salivary cortisol concentration between C and NC were found at any stage of the trial. Eye temperature increased significantly in ALL horses during SC, peaking at +10 min into the procedure (p b 0.05) and then decreased substantially when SC had ceased (p b 0.01). Although no significant differences were found between C and NC per se, there was a significant interaction between group and phase of trial (p b 0.05) with the NC group showing a greater decrease in eye temperature post SC. There was a significant positive correlation between changes in salivary cortisol concentration and eye temperature (p b 0.01) but no correlation between any of the other measures. Although the behavioral response of C and NC to this procedure was significantly different the physiological responses indicated that ALL horses found the procedure aversive. Eye temperature could be used as an objective and immediate measure of how an animal is responding to a specific situation in order to evaluate management procedures and adapt them where appropriate to reduce the negative impact on animal health and welfare

    Evaluation of the uniformity of sound-masking systems in an open-plan office

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    Many open-plan offices adopt an electronic sound masking system in order to reduce distraction from background noises, primarily intruding speech. Sound masking systems should uniformly generate a masking sound over the entire office area to homogenize the speech privacy whilst minimising occupant perception of the masking sound. This study evaluates the spatial uniformity of the masking sound field in an example open-plan office, where the masking system was set up to represent supposedly optimal installation conditions; 1-speaker zones, individually-calibration of each zone to match the specified curve precisely, and smaller zones than typically specified. Sound level measurements performed as per ASTM E1573-18 were made at each workstation, as well as every 0.6 m across the office, for a total of 117 measurements. Measurement results show that tolerance of ± 0.5 dB for the overall A-weighted level is only achievable at 61% of measurement locations, whilst ± 1 dB is achievable at 99% of locations. For one-third-octave band sound pressure levels between 250 Hz to 4 kHz, ± 2 dB is achieved only 55% of the time, and tolerance of ± 3.5 dB is required to achieve 95% compliance with the specified curve. By using calibrated computer simulations, the study also examined parameters that can influence spatial uniformity in open-plan offices. It was found that the number of sound masking loudspeakers, partition height, and the scattering and absorption coefficient of the ceiling all affect the uniformity of the masking sound. Speech intelligibility was assessed by calculating the Articulation Index (AI) to determine an acceptable tolerance for masking sound variation. Increasing the number of loudspeakers was the most effective way to improve the uniformity of the masking sound. The AI results suggest ±2 dB, when including octave band sound pressure levels, is a minimum required tolerance for a sound masking sound field in an open office to provide AI values within ±0.1 of the targeted value across the office area

    Evaluation of Three Adolescent Sexual Health Programs in Ha Noi and Khanh Hoa Province, Vietnam

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    With an increase in sexual activity among young adults in Vietnam and associated risks, there is a need for evidence-based sexual health interventions. This evaluation of three sexual health programs based on the Protection Motivation Theory (PMT) was conducted in 12 communes in Ha Noi, Nha Trang City, and Ninh Hoa District. Inclusion criteria included unmarried youth 15–20 years residing in selected communes. Communes were randomly allocated to an intervention, and participants were randomly selected within each commune. The intervention programs included Vietnamese Focus on Kids (VFOK), the gender-based program Exploring the World of Adolescents (EWA), and EWA plus parental and health provider education (EWA+). Programs were delivered over a ten-week period in the communities by locally trained facilitators. The gender-based EWA program with parental involvement (EWA+) compared to VFOK showed significantly greater increase in knowledge. EWA+ in comparison to VFOK also showed significant decrease at immediate postintervention for intention to have sex. Sustained changes are observed in all three interventions for self-efficacy condom use, self-efficacy abstinence, response efficacy for condoms, extrinsic rewards, and perceived vulnerability for HIV. These findings suggest that theory-based community programs contribute to sustained changes in knowledge and attitudes regarding sexual risk among Vietnamese adolescents
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