3,495 research outputs found

    On BPS bounds in D=4 N=2 gauged supergravity II: general matter couplings and black hole masses

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    We continue the analysis of BPS bounds started in arXiv:1110.2688, extending it to the full class of N=2 gauged supergravity theories with arbitrary vector and hypermultiplets. We derive the general form of the asymptotic charges for asymptotically flat (M_4), anti-de Sitter (AdS_4), and magnetic anti-de Sitter (mAdS_4) spacetimes. Some particular examples from black hole physics are given to explicitly demonstrate how AdS and mAdS masses differ when solutions with non-trivial scalar profiles are considered.Comment: 21 pages; v2 added reference, published version; v3 minor correction

    Different Approaches to Assess the Welfare of Dairy Cows with Some Results in Serbia

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    In this paper, different methodologies for assessing the welfare of dairy cows, such as Animal Needs Index, system of welfare indicators, system of behaviour indicators and the Welfare Quality® assessment protocol for cattle were discussed. Also, the results of the usage of these methodologies in Serbia were analyzed. In the last several years in the country, numerous studies have been conducted about welfare of dairy cattle. State of welfare of dairy cows, on farms with tied and free system estimated by mentioned methodologies was generally acceptable. The major problems in the welfare of cows are insufficient amounts of floor litter, lack of cow access to outdoor runs or pasture, occurrence of lameness, dystocia, downer cow syndrome and mortality, the manifestation of aggression between the animals and improper relationship between stockmen and animals. On the basis of the results, it can be stated that in Serbia only recently enough attention has been paid to monitoring and understanding the current welfare state of dairy cows, which are the first important steps to achieve improvements in practical terms

    On estimating the surface wind stress over the sea

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    Author Posting. © American Meteorological Society, 2018. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 48 (2018): 1533-1541, doi:10.1175/JPO-D-17-0267.1.Our study analyzes measurements primarily from two Floating Instrument Platform (FLIP) field programs and from the Air–Sea Interaction Tower (ASIT) site to examine the relationship between the wind and sea surface stress for contrasting conditions. The direct relationship of the surface momentum flux to U2 is found to be better posed than the relationship between and U, where U is the wind speed and is the friction velocity. Our datasets indicate that the stress magnitude often decreases significantly with height near the surface due to thin marine boundary layers and/or enhanced stress divergence close to the sea surface. Our study attempts to correct the surface stress estimated from traditional observational levels by using multiple observational levels near the surface and extrapolating to the surface. The effect of stability on the surface stress appears to be generally smaller than errors due to the stress divergence. Definite conclusions require more extensive measurements close to the sea surface.This work was supported by the U.S. Office of Naval Research through Award N00014-16-1-2600. We2019-01-1

    Reproductive and Related Disorders on Dairy Farms with Different Levels of Welfare Quality

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    In this paper reproductive results of six dairy cows farms with total of 766 (farm 1 – 107; farm 2 –175; farm 3 – 49; farm 4 – 400; farm 5 –20 and farm 6 – 11 milking cows) with different system of rearing and welfare level were analyzed. A dairy cow reproductive efficiency is a key factor for milk production - impaired reproductive performance is a major cause of reduced production in dairy industry. Welfare and reproductive disorders data were collected by questionnaire regarding criteria of Animal Need Index (ANI – Bartussek et al., 2000) and compared by multidimensional criteria of total discriminating effect. Possibility of movement, lighting and air quality in the accommodation facility, type and quality of floor, possibility of social contacts with other cows and interaction of stockman with cattle were compared and analysed in respect of farm welfare. In respect to the welfare level of lowest ranked farm (farm 6), farms 1, 2, 3, 4, 5 and 6 were ranked as 4th, 2nd, 1st, 5th, 3rd, and 6th, respectively, but in respect to the reproductive and related disorders occurrence rate lowest ranked farm (farm 4), farms 1, 2, 3, 4, 5 and 6 were ranked as 1st, 4th, 2nd, 6th, 5th and 3rd. Discrepancy derives from the fact that reproduction data were collected for a year, while welfare assessment describes reached level in on particular moment of time, not covering all potential causes of reproductive disorders. Reduced reproductive success would seem promising as information about poor farm welfare, although good results often are not related to good welfare. Nevertheless, assessed welfare protection level provides important information about herd health and potential reproduction problems, pointing out that there are many opportunities for improving the quality of the welfare of dairy cows, mostly through improving the housing conditions of dairy cows

    Otpornost na kontrolisani termalni stres i tolerancija na zamrzavanje spermatozoida dve grupe nerastova

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    The aim of this study was to find out is it possible to presume success of boars sperm cryopreservation, based on controlled exposure to heat stress and to investigate in vitro quality parameters of frozen/thawed sperm of previously selected 6 boars with good results (group 1) and 6 boars (group 2) with bad results on thermo resistance test (TT). In this investigation, ejaculates of 12 chosen of 75 AI boars (Landrace, Large White, Pietrain and Durock breeds) from SVC Velika Plana (Serbia) were used. Tolerance to heat stress was performed by Schaetz (1963) method. Ejaculates were extended with Androhep plus (1:1) and kept during 60 minutes on 41oC. In cryopreservation of boars semen Westendorf et al. (1975) method, modified by Bwanga et al. (1990). Very significant changes of progressive motility rate were observed after spermatozoa exposure to controlled thermal stress. High correlation coefficient of progressive motility rate of both groups of boars, but higher in group 2 for progressive motility rate after thawing and after heat stress treatment was established. Average progressive motility rate of all 12 boars did not differ before and after thawing. Presence of boars of all breeds represented in the SVC (Large White, Landrace, Duroc and Pietrain) in both quality groups confirms the assumption that suitability for cryopreservation of sperm is individual trait. According data analysis, sperm deep freezing success requires previous selection for potential donors, which have to be consider standard quality parameters testing and controlled stress exposure tests.Cilj rada je da se ustanovi da li moguće odrediti da li je sperma nerasta pogodna za krioprezervaciju da se na osnovu izlaganja spermatozioda kontrolisanom toplotnom stresu i da se ispitaju in vitro parametri kvaliteta odmrznutog semena dve grupe od po 6 nerastova čije je seme dobro (1. grupa) ili loše podnelo toplotni stres (2. grupa). U istraživanju su korišćeni ejakulati 12 od 75 nerastova rasa: landras, veliki jorkšir, pijetren i durok (L, J, P, D) iz SVC Velika Plana, odabranih na osnovu testa termorezistencije (TT) i svrstanih u dve kvalitetne grupe. Ispitivanje stepena termorezistencije ejakulata u razređenju Androhep-om plus 1:1 60 minuta na 41 oC, je izvedeno metodom po Schaetz-u (1963). Duboko zamrzavanje sperme odabranih nerastova izvedeno modifikovanim postupkom po Westendorf-u i sar. (1975) i Bwanga-i i sar. (1990). Rezultati TT ukazali su na vrlo značajne promene progresivne pokretljivosti spermatozoida posle izlaganja kontrolisanom toplotnom stresu. Ustanovljen je visok koeficijent korelacije kod obe grupe ali ipak nešto viši kod nerastova 2. grupe za odnos procenta progresivne pokretljivosti spermatozoida posle odmrzavanja i progresivne pokretljivosti posle izlaganja temperaturi od 41oC. Prosečna progresivna pokretljivost spermatozoida svih ispitivanih nerastova se nije značajno razlikovala pre i posle zamrzavanja. Slučajni raspored nerastova svih rasa zastupljenih u SVC (Jorkšir, Landras, Durok i Pijetren) u obe kvalitetne grupe potvrđuje pretpostavku da je pogodnost sperme za krioprezervaciju individualna osobina. Za uspešnu krioprezervaciju sperme nerastova je neophodna prethodna selekcija potencijalnih donora na osnovu rezultata ispitivanja standardnih parametara kvaliteta i testova u kojima se spermatozoidi in vitro izlažu različitim kontrolisanom stresu

    The Herschel-SPIRE instrument and its in-flight performance

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    The Spectral and Photometric Imaging REceiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194–671 μm (447–1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4´× 8´, observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6´. The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5–2

    Approximate Solutions to Fractional Subdiffusion Equations: The heat-balance integral method

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    The work presents integral solutions of the fractional subdiffusion equation by an integral method, as an alternative approach to the solutions employing hypergeometric functions. The integral solution suggests a preliminary defined profile with unknown coefficients and the concept of penetration (boundary layer). The prescribed profile satisfies the boundary conditions imposed by the boundary layer that allows its coefficients to be expressed through its depth as unique parameter. The integral approach to the fractional subdiffusion equation suggests a replacement of the real distribution function by the approximate profile. The solution was performed with Riemann -Liouville time-fractional derivative since the integral approach avoids the definition of the initial value of the time-derivative required by the Laplace transformed equations and leading to a transition to Caputo derivatives. The method is demonstrated by solutions to two simple fractional subdiffusion equations (Dirichlet problems): 1) Time-Fractional Diffusion Equation, and 2) Time-Fractional Drift Equation, both of them having fundamental solutions expressed through the M-Write function. The solutions demonstrate some basic issues of the suggested integral approach, among them: a) Choice of the profile, b) Integration problem emerging when the distribution (profile) is replaced by a prescribed one with unknown coefficients; c) Optimization of the profile in view to minimize the average error of approximations; d) Numerical results allowing comparisons to the known solutions expressed to the M-Write function and error estimations.Comment: 15 pages, 7 figures, 3 table

    BPS black holes in N=2 D=4 gauged supergravities

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    We construct and analyze BPS black hole solutions in gauged N=2, D=4 supergravity with charged hypermultiplets. A class of solutions can be found through spontaneous symmetry breaking in vacua that preserve maximal supersymmetry. The resulting black holes do not carry any hair for the scalars. We demonstrate this with explicit examples of both asymptotically flat and anti-de Sitter black holes. Next, we analyze the BPS conditions for asymptotically flat black holes with scalar hair and spherical or axial symmetry. We find solutions only in cases when the metric contains ripples and the vector multiplet scalars become ghost-like. We give explicit examples that can be analyzed numerically. Finally, we comment on a way to circumvent the ghost-problem by introducing also fermionic hair.Comment: 40 pages, 2 figures; v2 references added; v3 minor changes, published versio

    Interstellar dust in the BOOMERanG maps

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    Interstellar dust (ISD) emission is present in the mm-wave maps obtained by the BOOMERanG experiment at intermediate and high Galactic latitudes. We find that, while being sub-dominant at the lower frequencies (90,150, 240 GHz), thermal emission from ISD is dominant at 410 GHz, and is well correlated with the IRAS map at 100 µm. We find also that the angular power spectrum of ISD fluctuations at 410 GHz is a power law, and its level is negligible with respect to the angular power spectrum of the Cosmic Microwave Background (CMB) at 90 and 150 GHz

    Spin-Wave Theory of the Spiral Phase of the t-J Model

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    A graded H.P,realization of the SU(2|1) algebra is proposed.A spin-wave theory with a condition that the sublattice magnetization is zero is discussed.The long-range spiral phase is investigated.The spin-spin correlator is calculated.Comment: 17 page
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