1,199 research outputs found

    Motion and gravitational radiation of a binary system consisting of an oscillating and rotating coplanar dusty disk and a point-like object

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    A binary system composed of an oscillating and rotating coplanar dusty disk and a point mass is considered. The conservative dynamics is treated on the Newtonian level. The effects of gravitational radiation reaction and wave emission are studied to leading quadrupole order. The related waveforms are given. The dynamical evolution of the system is determined semi-analytically exploiting the Hamiltonian equations of motion which comprise the effects both of the Newtonian tidal interaction and the radiation reaction on the motion of the binary system in elliptic orbits. Tidal resonance effects between orbital and oscillatory motions are considered in the presence of radiation damping.Comment: 26 pages, 8 figure

    Fixture knowledge model development and implementation based on a functional design approach

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    The development of a knowledge model applied to fixture design is a complex task. The main purpose of such model is the development of a knowledge-based application to assist fixture designers. It comprises a detailed specification of the types and structures of data involved in the execution of the inference process needed to create a fixture solution for machining a raw part. A development method together with a knowledge model for automating fixture design is proposed. The development was divided into three parts: Design Process Model, definition of Top-level functional functions and Product Knowledge Model. Adopting a functional design approach, the fixture design solution was created in two levels: functional and detailed. The functional level is based on fixture functional elements and the detailed one is based on fixture commercial elements. The definitions and concepts used in the application are specified in several Units of Knowledge (UoK) that comprises the Fixture Knowledge Model. Common Knowledge Analysis and Design Structuring (CommonKADS), Methodology and software tools Oriented to KBE Applications (MOKA), Integrated DEFinition for Function Modelling (IDEF0) and Unified Modelling Language (UML) are the methodologies and techniques used in the proposed method. Finally, a prototype KBE application for fixture design was developed

    Simvastatin Prevents and Reverses Depigmentation in a Mouse Model of Vitiligo

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    Vitiligo is a common autoimmune disease of the skin that results in disfiguring white spots. There are no Food and Drug Administration (FDA)-approved treatments, and current treatments are time-consuming, expensive, and of low efficacy. We sought to identify new treatments for vitiligo, and first considered repurposed medications because of the availability of safety data and expedited regulatory approval. We previously reported that the IFN-γ-induced chemokine CXCL10 is expressed in lesional skin from vitiligo patients, and that it is critical for the progression and maintenance of depigmentation in our mouse model of vitiligo. We hypothesized that targeting IFN-γ signaling might be an effective new treatment strategy. Activation of signal transducer and activator of transcription 1 (STAT1) is required for IFN-γ signaling and recent studies revealed that simvastatin, an FDA-approved cholesterol-lowering medication, inhibited STAT1 activation in vitro. Therefore, we hypothesized that simvastatin may be an effective treatment for vitiligo. We found that simvastatin both prevented and reversed depigmentation in our mouse model of vitiligo, and reduced the number of infiltrating autoreactive CD8+ T cells in the skin. Treatment of melanocyte-specific, CD8+ T cells in vitro decreased proliferation and IFN-γ production, suggesting additional effects of simvastatin directly on T cells. Based on these data, simvastatin may be a safe, targeted treatment option for patients with vitiligo. © 2015 The Society for Investigative Dermatology

    The extraordinary outburst in the massive protostellar system NGC 6334 I-MM1 : strong increase in mid-infrared continuum emission

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    Financial support for this work was provided by NASA through award #07_0156 issued by USRA. Based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 089.C-0852(A).In recent years, dramatic outbursts have been identified toward massive protostars via infrared and millimeter dust continuum and molecular maser emission. The longest lived outburst (>6 yr) persists in NGC 6334 I-MM1, a deeply embedded object with no near-IR counterpart. Using FORCAST and HAWC+ on SOFIA, we have obtained the first mid-IR images of this field since the outburst began. Despite being undetected in pre-outburst ground-based 18 μm images, MM1 is now the brightest region at all three wavelengths (25, 37, and 53 μm), exceeding the UCHII region MM3 (NGC 6334 F). Combining the SOFIA data with ALMA imaging at four wavelengths, we construct a spectral energy distribution of the combination of MM1 and the nearby hot core MM2. The best-fit Robitaille radiative transfer model yields a luminosity of (4.9 ± 0.8) × 104 L⊙. Accounting for an estimated pre-outburst luminosity ratio MM1:MM2 = 2.1 ± 0.4, the luminosity of MM1 has increased by a factor of 16.3 ± 4.4. The pre-outburst luminosity implies a protostar of mass 6.7 M⊙, which can produce the ionizing photon rate required to power the pre-outburst HCHII region surrounding the likely outbursting protostar MM1B. The total energy and duration of the outburst exceed the S255IR-NIRS3 outburst by a factor of 3, suggesting a different scale of event involving expansion of the protostellar photosphere (to 20 R⊙), thereby supporting a higher accretion rate (0.0023 M⊙ yr−1) and reducing the ionizing photon rate. In the grid of hydrodynamic models of Meyer et al., the combination of outburst luminosity and magnitude (3) places the NGC 6334 I-MM1 event in the region of moderate total accretion (~0.1–0.3 M⊙) and hence long duration (~40–130 yr).PostprintPeer reviewe

    PCN77 – Cost-effectiveness of cognitive-behavioral therapy and physical exercise for alleviating treatment-induced menopausal symptoms in breast cancer patients

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    Objectives Many breast cancer patients suffer from (severe) menopausal symptoms after an early onset of menopause caused by cancer treatment. The standard treatment for these complaints is hormone replacement therapy, which, however, is contraindicated for this group, as it may have tumor-promoting effects. The aim of this study was to assess the cost-effectiveness of three interventions aimed at alleviating these symptoms: cognitive-behavioral therapy (CBT), physical exercise (PE), and the combination of both (CBT+PE). Methods A cost-effectiveness analysis was performed from a health care system perspective. The primary outcome was incremental health care costs (IHCC) per patient with a clinically relevant improvement after six months of treatments. The secondary outcome was incremental costs per quality-adjusted life years (QALYs) gained over a five-year time period. This was assessed using a Markov model, populated with data from a recent randomized controlled trial evaluating the effectiveness of CBT, PE, and CBT+PE in the clinical setting and additional cost data. The robustness of the results was analyzed through one-way and probabilistic sensitivity analyses. Results IHCCs for alleviating one patient of the perceived symptom burden by a clinically relevant difference after six months of treatment were EUR€605 for CBT, EUR€1,847 for CBT+PT, and EUR€1,250 for PE alone, compared to the waiting list control group. CBT generated 0.009 additional QALYs at an additional cost of EUR€162, compared to the control group, leading to an Incremental Cost Utility Ratio (ICUR) of EUR€18,655 per QALY gained and The ICUR of CBT+PE was EUR€42,375 per QALY in comparison to the control group. CBT had a high probability (circa 61%) of being cost-effective at prevailing ceiling ratios. Conclusions CBT is likely the most cost-effective of the three interventions investigated for alleviating treatment-induced menopausal symptoms in breast cancer patient

    Augmenting light coverage for photosynthesis through YFP-enhanced charge separation at the Rhodobacter sphaeroides reaction centre.

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    Photosynthesis uses a limited range of the solar spectrum, so enhancing spectral coverage could improve the efficiency of light capture. Here, we show that a hybrid reaction centre (RC)/yellow fluorescent protein (YFP) complex accelerates photosynthetic growth in the bacterium Rhodobacter sphaeroides. The structure of the RC/YFP-light-harvesting 1 (LH1) complex shows the position of YFP attachment to the RC-H subunit, on the cytoplasmic side of the RC complex. Fluorescence lifetime microscopy of whole cells and ultrafast transient absorption spectroscopy of purified RC/YFP complexes show that the YFP-RC intermolecular distance and spectral overlap between the emission of YFP and the visible-region (QX) absorption bands of the RC allow energy transfer via a Förster mechanism, with an efficiency of 40±10%. This proof-of-principle study demonstrates the feasibility of increasing spectral coverage for harvesting light using non-native genetically-encoded light-absorbers, thereby augmenting energy transfer and trapping in photosynthesis

    Farmland Prices: Is This Time Different?

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    The historical behavior of farmland prices, rental rates, and rates of return are examined by treating farmland as an asset with an infinitely long life. It is found that high (low) farmland prices relative to rents have historically preceded extended periods of low (high) net rates of return, rather than greater (smaller) growth in rents. Our analysis shows that this attribute is shared with stocks and housing, and the financial literature provides ample evidence that other assets feature it as well. The long-run relationship linking farmland prices, rents, and rates of return is analyzed. Based on this relationship, we conclude that recent trends are unlikely to be sustainable. The study explores the expected paths that farmland prices and rates of return might follow if they were to eventually conform to the average values observed in the historical sample, and concludes with a discussion of the policy implications. Recommendations for policy makers include close monitoring of farmland lending practices and institutions to allow early identification of potential problems, and identifying in advance appropriate interventions in case recent farmland market trends were to suddenly change

    A New Approach to Searching for Dark Matter Signals in Fermi-LAT Gamma Rays

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    Several cosmic ray experiments have measured excesses in electrons and positrons, relative to standard backgrounds, for energies from ~ 10 GeV - 1 TeV. These excesses could be due to new astrophysical sources, but an explanation in which the electrons and positrons are dark matter annihilation or decay products is also consistent. Fortunately, the Fermi-LAT diffuse gamma ray measurements can further test these models, since the electrons and positrons produce gamma rays in their interactions in the interstellar medium. Although the dark matter gamma ray signal consistent with the local electron and positron measurements should be quite large, as we review, there are substantial uncertainties in the modeling of diffuse backgrounds and, additionally, experimental uncertainties that make it difficult to claim a dark matter discovery. In this paper, we introduce an alternative method for understanding the diffuse gamma ray spectrum in which we take the intensity ratio in each energy bin of two different regions of the sky, thereby canceling common systematic uncertainties. For many spectra, this ratio fits well to a power law with a single break in energy. The two measured exponent indices are a robust discriminant between candidate models, and we demonstrate that dark matter annihilation scenarios can predict index values that require "extreme" parameters for background-only explanations.Comment: v1: 11 pages, 7 figures, 1 table, revtex4; v2: 13 pages, 8 figures, 1 table, revtex4, Figure 4 added, minor additions made to text, references added, conclusions unchanged, published versio

    Dynamic Evolution of a Quasi-Spherical General Polytropic Magnetofluid with Self-Gravity

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    In various astrophysical contexts, we analyze self-similar behaviours of magnetohydrodynamic (MHD) evolution of a quasi-spherical polytropic magnetized gas under self-gravity with the specific entropy conserved along streamlines. In particular, this MHD model analysis frees the scaling parameter nn in the conventional polytropic self-similar transformation from the constraint of n+γ=2n+\gamma=2 with γ\gamma being the polytropic index and therefore substantially generalizes earlier analysis results on polytropic gas dynamics that has a constant specific entropy everywhere in space at all time. On the basis of the self-similar nonlinear MHD ordinary differential equations, we examine behaviours of the magnetosonic critical curves, the MHD shock conditions, and various asymptotic solutions. We then construct global semi-complete self-similar MHD solutions using a combination of analytical and numerical means and indicate plausible astrophysical applications of these magnetized flow solutions with or without MHD shocks.Comment: 21 pages, 7 figures, accepted for publication in APS
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