5,873 research outputs found

    An Econometric Examination of the New Federalism

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    macroeconomics, econometrics, Federalism

    Adaptive HIV-1 evolutionary trajectories are constrained by protein stability

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    Despite the use of combination antiretroviral drugs for the treatment of HIV-1 infection, the emergence of drug resistance remains a problem. Resistance may be conferred either by a single mutation or a concerted set of mutations. The involvement of multiple mutations can arise due to interactions between sites in the amino acid sequence as a consequence of the need to maintain protein structure. To better understand the nature of such epistatic interactions, we reconstructed the ancestral sequences of HIV-1's Pol protein, and traced the evolutionary trajectories leading to mutations associated with drug resistance. Using contemporary and ancestral sequences we modelled the effects of mutations (i.e. amino acid replacements) on protein structure to understand the functional effects of residue changes. Although the majority of resistance-associated sequences tend to destabilise the protein structure, we find there is a general tendency for protein stability to decrease across HIV-1's evolutionary history. That a similar pattern is observed in the non-drug resistance lineages indicates that non-resistant mutations, for example, associated with escape from the immune response, also impacts on protein stability. Maintenance of optimal protein structure therefore represents a major constraining factor to the evolution of HIV-1

    ‘My journey through the system’: a grounded theory of service user-perceived experiences of recovery in forensic mental health services

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    The ‘Recovery Approach’ is widely regarded as the guiding principle for mentalhealth service delivery in the UK. Forensic services face unique challenges in applying this approach. Numerous studies have explored themes associated with recovery in these settings but it is unclear how themes relate to each other. This study set out to build a theoretical model of service user experiences of recovery in forensic mental health settings. Semi-structured interviews were conducted with 16 service users about their recovery. Grounded Theory methodology, with a constructivist epistemology, was used to analyse the data. A cyclical model was developed, with five-core recovery processes that interrelated; these were the environment, connectedness, hope for the future, who I am and empowerment. These occurred in three phases of 1) feeling safe and secure, 2) moving forward, and 3) empowerment. These processes were encompassed by two additional themes of arriving at the hospital and changes over time. This study is the first to provide a clear model of service user experiences of recovery in this setting

    Orientation to the sun by animals and its interaction with crypsis

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    1. Orientation with respect to the sun has been observed in a wide range of species and hasgenerally been interpreted in terms of thermoregulation and/or ultraviolet (UV) protection. For countershaded animals, orientation with respect to the sun may also result from the pres-sure to exploit the gradient of coloration optimally to enhance crypsis.2. Here, we use computational modelling to predict the optimal countershading pattern for anoriented body. We assess how camouflage performance declines as orientation varies using acomputational model that incorporates realistic lighting environments.3. Once an optimal countershading pattern for crypsis has been chosen, we determineseparately how UV protection/irradiation and solar thermal inflow fluctuate with orientation.4. We show that body orientations that could optimally use countershading to enhance crypsisare very similar to those that allow optimal solar heat inflow and UV protection.5. Our findings suggest that crypsis has been overlooked as a selective pressure on orientationand that new experiments should be designed to tease apart the respective roles of these different selective pressures. We propose potential experiments that could achieve this

    Individualisation of time-motion analysis : a method comparison and case report series

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    © Georg Thieme Verlag KG. This study compared the intensity distribution of time-motion analysis data, when speed zones were categorized by different methods. 12 U18 players undertook a routine battery of laboratory- and field-based assessments to determine their running speed corresponding to the respiratory compensation threshold (RCT), maximal aerobic speed (MAS), maximal oxygen consumption (vVO 2max ) and maximal sprint speed (MSS). Players match-demands were tracked using 5 Hz GPS units in 22 fixtures (50 eligible match observations). The percentage of total distance covered running at high-speed (%HSR), very-high speed (%VHSR) and sprinting were determined using the following speed thresholds: 1) arbitrary; 2) individualised (IND) using RCT, vVO 2max and MSS; 3) individualised via MAS per se; 4) individualised via MSS per se; and 5) individualised using MAS and MSS as measures of locomotor capacities (LOCO). Using MSS in isolation resulted in 61 % and 39 % of player's % HSR and % VHSR, respectively, being incorrectly interpreted, when compared to the IND technique. Estimating the RCT from fractional values of MAS resulted in erroneous interpretations of % HSR in 50 % of cases. The present results suggest that practitioners and researchers should avoid using singular fitness characteristics to individualise the intensity distribution of time-motion analysis data. A combination of players' anaerobic threshold, MAS, and MSS characteristics are recommended to individualise player-tracking data

    Tracking with Multiple Cameras for Video Surveillance

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    The large shape variability and partial occlusions challenge most object detection and tracking methods for nonrigid targets such as pedestrians. Single camera tracking is limited in the scope of its applications because of the limited field of view (FOV) of a camera. This initiates the need for a multiple-camera system for completely monitoring and tracking a target, especially in the presence of occlusion. When the object is viewed with multiple cameras, there is a fair chance that it is not occluded simultaneously in all the cameras. In this paper, we developed a method for the fusion of tracks obtained from two cameras placed at two different positions. First, the object to be tracked is identified on the basis of shape information measured by MPEG-7 ART shape descriptor. After this, single camera tracking is performed by the unscented Kalman filter approach and finally the tracks from the two cameras are fused. A sensor network model is proposed to deal with the situations in which the target moves out of the field of view of a camera and reenters after sometime. Experimental results obtained demonstrate the effectiveness of our proposed scheme for tracking objects under occlusion

    Selective Feeding By Zooplankton: Implications For Lake Productivity

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    Recalibrating the cosmic star formation history

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    The calibrations linking observed luminosities to the star formation rate depend on the assumed stellar population synthesis model, initial mass function, star formation and metal enrichment history, and whether reprocessing by dust and gas is included. Consequently the shape and normalisation of the inferred cosmic star formation history is sensitive to these assumptions. Using v2.2.1 of the Binary Population and Spectral Synthesis (\bpass) model we determine a new set of calibration coefficients for the ultraviolet, thermal-infrared, and, hydrogen recombination lines. These ultraviolet and thermal infrared coefficients are 0.15-0.2 dex higher than those widely utilised in the literature while the Hα\alpha coefficient is 0.35\sim 0.35 dex larger. These differences arise in part due to the inclusion binary evolution pathways but predominantly reflect an extension in the IMF to 300 MM_{\odot} and a change in the choice of reference metallicity. We use these new coefficients to recalibrate the cosmic star formation history, and find improved agreement between the integrated cosmic star formation history and the in-situ measured stellar mass density as a function of redshift. However, these coefficients produce new tension between star formation rate densities inferred from the ultraviolet and thermal-infrared and those from Hα\alpha.Comment: 7 pages, 8 figures, accepted for publication in MNRA
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