8,941 research outputs found

    A General Framework for Fair Regression

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    Fairness, through its many forms and definitions, has become an important issue facing the machine learning community. In this work, we consider how to incorporate group fairness constraints in kernel regression methods, applicable to Gaussian processes, support vector machines, neural network regression and decision tree regression. Further, we focus on examining the effect of incorporating these constraints in decision tree regression, with direct applications to random forests and boosted trees amongst other widespread popular inference techniques. We show that the order of complexity of memory and computation is preserved for such models and tightly bound the expected perturbations to the model in terms of the number of leaves of the trees. Importantly, the approach works on trained models and hence can be easily applied to models in current use and group labels are only required on training data.Comment: 8 pages, 4 figures, 2 pages reference

    Support minimized nonlinear acoustic inversion with absolute phase error correction

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    The predominant factors which prohibit the inversion of acoustic scattering data for the purposes of flaw characterization are 1) limited angular access to the flaw, 2) limited temporal frequency signal bandwidth, and 3) lack of absolute phase information between individual measurements (zero of time problem). An additional complication which impedes the data inversion is the non-linear dependence of the scattering data on the scattering object. This problem must be handled by either linearizing the problem or by applying an iterative procedure which may have questionable convergence properties. An approach to data inversion is presented here which shows potential in overcoming the aforementioned difficulties. This approach compensates for the lack of data by constructing a solution which yields simulated scattering consistent with the measured data, while simultaneously minimizing a functional measure of the support (i.e. volume) of the flaw. Such an approach to limited data inversion has proven effective in limited view X-ray CT applications when reconstructing discontinuous boundary flaws such as cracks and inclusions [1, 2, 3]. The application presented here is by-and-large analogous to the X-ray CT application, except for the additional complication of the lack of absolute phase between measurements. This zero-of-time problem is handled here by treating the absolute phase of each measurement as a variable in the minimization of the flaw support

    Investigating the Effect of Stratospheric Radiation on Seed Germination and Growth

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    Three seed types: bean (Phaseolus vulgaris), corn (Zea mays) and radish (Raphanus sativus) were flown in a high altitude weather balloon into the mid-stratosphere to investigate the effects of high altitude radiation on germination success and seedling growth. After recovering and planting the seeds, the bean seeds showed lower germination success with exposure to high altitude radiation, and consequently stunted seedling growth. Cord and radish seeds experienced a statistically significant positive effect on germination success form radiation exposure compared to control seeds, but negative effect on seedling growth. Overall, the field experiments presented here support laboratory studies that show radiation exposure on vegetable seeds has a mixed effect on the germination success and negative effect on seedling growth on investigated seed types

    Impact of Traffic Characteristics on Request Aggregation in an NDN Router

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    The paper revisits the performance evaluation of caching in a Named Data Networking (NDN) router where the content store (CS) is supplemented by a pending interest table (PIT). The PIT aggregates requests for a given content that arrive within the download delay and thus brings an additional reduction in upstream bandwidth usage beyond that due to CS hits. We extend prior work on caching with non-zero download delay (non-ZDD) by proposing a novel mathematical framework that is more easily applicable to general traffic models and by considering alternative cache insertion policies. Specifically we evaluate the use of an LRU filter to improve CS hit rate performance in this non-ZDD context. We also consider the impact of time locality in demand due to finite content lifetimes. The models are used to quantify the impact of the PIT on upstream bandwidth reduction, demonstrating notably that this is significant only for relatively small content catalogues or high average request rate per content. We further explore how the effectiveness of the filter with finite content lifetimes depends on catalogue size and traffic intensity

    B--> K^* l^+ l^- decay in the two Higgs doublet model with flavor changing neutral currents

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    We study the decay width, forward-backward asymmetry and the longitudinal lepton polarization for the exclusive decay B --> K^* l^+ l^- in the two Higgs doublet model with three level flavor changing neutral currents (model III) and analyse the dependencies of these quantities on the the selected parameters, \xi^{U,D}, of model III including the next to leading QCD corrections. It is found that to look for charged Higgs effects, the measurements of the branching ratio, forward-backward asymmetry and the longitudinal lepton polarization for the decay B --> K^* l^+ l^- are promising.Comment: 17 pages, 6 figure

    A systematic review of resilience and mental health outcomes of conflict-driven adult forced migrants.

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    BACKGROUND: The rising global burden of forced migration due to armed conflict is increasingly recognised as an important issue in global health. Forced migrants are at a greater risk of developing mental disorders. However, resilience, defined as the ability of a person to successfully adapt to or recover from stressful and traumatic experiences, has been highlighted as a key potential protective factor. This study aimed to review systematically the global literature on the impact of resilience on the mental health of adult conflict-driven forced migrants. METHODOLOGY: Both quantitative and qualitative studies that reported resilience and mental health outcomes among forcibly displaced persons (aged 18+) by way of exploring associations, links, pathways and causative mechanisms were included. Fourteen bibliographic databases and seven humanitarian study databases/websites were searched and a four stage screening process was followed. RESULTS: Twenty three studies were included in the final review. Ten qualitative studies identified highlighted family and community cohesion, family and community support, individual personal qualities, collective identity, supportive primary relationships and religion. Thirteen quantitative studies were identified, but only two attempted to link resilience with mental disorders, and three used a specific resilience measure. Over-reliance on cross-sectional designs was noted. Resilience was generally shown to be associated with better mental health in displaced populations, but the evidence on this and underlying mechanisms was limited. DISCUSSION: The review highlights the need for more epidemiological and qualitative evidence on resilience in forcibly displaced persons as a potential avenue for intervention development, particularly in resource-poor settings

    Long Term Tropospheric and Stratospheric Measurements Using High Altitude Balloons

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    The Arkansas BalloonSAT program is an educational outreach and research program at Arkansas State University. A variety of instruments including HOBO data loggers, Anasonde, and Arduino methane sensors have been flown on flights in the past five years. Measurements using BalloonSAT provides a cost effective option, while also matching measurements made with satellites and unmanned aerial vehicles. This includes identifying water vapor, pressure, background radiation, methane, carbon dioxide and temperature profiles over seasons and years. Water vapor trends were observed to vary with seasons, with water vapor lowest in the summer and greatest in the spring at stratospheric altitudes. Methane and carbon dioxide were observed to decrease with higher altitudes because of the greater distance from emission sources. Temperature measurements followed typical atmospheric profile measurements with an inversion at the stratosphere

    The preparation and culture of washed human sperm: a comparison of a suite of protein-free media with media containing human serum albumin

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    Objective To compare two suites of culture media (one with HSA and one protein-free (PF) supplemented with methylcellulose) for washing human sperm in IVF. Methods Semen samples (n = 41) underwent parallel density gradient preparation using PF or HSA-supplemented culture medium and subsequent yield, survival, morphology and motility were compared. Results The PF medium resulted in a significantly higher sperm yield (P \u3c 0.0001), but similar sperm morphology (P = 0.822) and 24-h survival (P = 0.11). There was, however, a lower percentage of progressively motile sperm (P \u3c 0.0001) and a higher proportion of sperm demonstrating non-progressive motility (P \u3c 0.0001) in the PF medium when observed on a Makler Chamber, apparently an artefact as a similar sperm motility index was measured using a Sperm Quality Analyser (P = 0.83). Attachment of sperm in PF medium to the glass chamber reduced with time and any differences had disappeared after 6 min on the counting chamber. Conclusion These results support the use of PF media supplemented with methylcellulose as an alternative to HSA, although a modification to the manufacturer\u27s protocol of 6-min pre-incubation before assessing sperm motility must be used. Further studies should investigate the function of such sperm prepared in PF medium

    Rare B -> K^* l^+ l^- decay, two Higgs doublet model, and light cone QCD sum rules

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    The decay width, forward-backward asymmetry and lepton longitudinal and transversal polarization for the exclusive K^* -> l^+ l^- decay in a two Higgs doublet model are computed. It is shown that all these quantities are very effective tools for establishing new physics.Comment: 18 pages, 7 figures, LaTeX formatte

    Chiral phase transition in a covariant nonlocal NJL model

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    The properties of the chiral phase transition at finite temperature and chemical potential are investigated within a nonlocal covariant extension of the Nambu-Jona-Lasinio model based on a separable quark-quark interaction. We consider both the situation in which the Minkowski quark propagator has poles at real energies and the case where only complex poles appear. In the literature, the latter has been proposed as a realization of confinement. In both cases, the behaviour of the physical quantities as functions of T and \mu is found to be quite similar. In particular, for low values of T the chiral transition is always of first order and, for finite quark masses, at certain "end point" the transition turns into a smooth crossover. In the chiral limit, this "end point" becomes a "tricritical" point. Our predictions for the position of these points are similar, although somewhat smaller, than previous estimates. Finally, the relation between the deconfining transition and chiral restoration is also discussed.Comment: 11 pages, 2 figures. Figures modified, minor changes in the text. To be published in Phys. Lett.
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