338 research outputs found

    TRACE ELEMENTS IN SHEEP AND GOATS REPRODUCTION: A REVIEW

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    The reproduction of small ruminants like goats and sheep managed under extensive range grazing conditions can be affected by nutrients availability and especially by the mineral content of the forages resources on the rangeland. It has been particularly demonstrated that trace elements can have equally, beneficial or detrimental effects, depending on its balance, on reproductive functions in small ruminants. Trace elements as copper, molybdenum, selenium and zinc play key role on the metabolism of carbohydrates, proteins and lipids; however, the mode of action by which these elements affect reproduction in sheep and goats are not completely understood, due to the complexity in the mode of action of the metallobiomolecules and the neuro-hormonal relationship. In this way, their absence or presence of these minerals in several organs, fluids, or tissues of the reproductive tract have allowed obtaining information on the metabolism and the role of these elements on reproduction in sheep and goats. On this regard, the objective of this document is to review the relationships and effects of some trace elements, on reproductive events in sheep and goats

    EFFECT OF SEASON ON SERUM COPPER AND ZINC CONCENTRATIONS IN CROSSBRED GOATS HAVING DIFFERENT REPRODUCTIVE STATUS UNDER SEMIARID RANGELAND CONDITIONS IN SOUTHERN MEXICO STATE

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    The effect of season (rainy: RS, and dry: DS) and reproductive status on copper (Cu) and zinc (Zn) concentrations in blood serum of crossbred goats (BW= 36.01 ± 1.59 kg) were studied under semiarid rangeland conditions in Southern Mexico State. Blood samples from 80 crossbred goats were taken each season (RS and DS). The goats were clustered into 10 different groups considering their reproductive status. Concentrations of Cu and Zn in serum were assayed using atomic absorption. Data were analyzed using a general linear model procedure for a completely randomized design and differences among means were examined using a Tukey test. Blood serum concentrations of Cu and Zn were affected by reproductive status and season (P<0.001). In relation to the season, Cu and Zn serum levels were lower in RS than DS (P<0.05). Overall, kidded goats had the highest values (P<0.01) for Cu than other animals in both seasons (RS or DS). Anestrous goats had the lowest concentrations (P<0.01) for Zn during RS, while all goats at their second or more kidding, rearing single or twins, showed the highest concentrations of Zn (P<0.001) in this season. Adult goats in Southern Mexico State showed a deficiency of Cu and Zn, especially during RS. As such, mineral supplements should be provided with respect to these elements in feeding systems for goats under semiarid rangeland conditions in order to evaluate their impact on health and reproduction

    Modelos de crecimiento y producción en España: historia, ejemplos contemporáneos y perspectivas

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    En el presente trabajo se presenta una revisión sobre los modelos forestales desarrollados en España durante los últimos años, tanto para la producción maderable como no maderable y, para la dinámica de los bosques (regeneración, mortalidad). Se presentan modelos tanto de rodal completo como de clases diamétricas y de árbol individual. Los modelos desarrollados hasta la fecha se han desarrollado a partir de datos procedentes de parcelas permanentes, ensayos y el Inventario Forestal Nacional. En el trabajo se muestran los diferentes submodelos desarrollados hasta la fecha, así como las plataformas informáticas que permiten utilizar dichos modelos. Se incluyen las principales perspectivas de desarrollo de la modelización forestal en España.In this paper we present a review of forest models developed in Spain in recent years for both timber and non timber production and forest dynamics (regeneration, mortality). Models developed are whole stand, size (diameter) class and individual-tree. The models developed to date have been developed using data from permanent plots, experimental sites and the National Forest Inventory. In this paper we show the different sub-models developed so far and the friendly use software. Main perspectives of forest modeling in Spain are presented.The models described in this paper were funded by different regional, national and European projects, and some of them were elaborated by the authors. This work was funded by the Spanish Government by the SELVIRED network (code AGL2008-03740) and the strategic project «Restauración y Gestión Forestal» (code PSE-310000-2009-4)

    Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory

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    We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to 8080^\circ and energies in excess of 4 EeV (4×10184 \times 10^{18} eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional information on any observed anisotropies. No deviation from isotropy is observed on any angular scale in the energy range between 4 and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no other deviation from isotropy is observed for moments beyond the dipole one. The corresponding pp-values obtained after accounting for searches blindly performed at several angular scales, are 1.3×1051.3 \times 10^{-5} in the case of the angular power spectrum, and 2.5×1032.5 \times 10^{-3} in the case of the needlet analysis. While these results are consistent with previous reports making use of the same data set, they provide extensions of the previous works through the thorough scans of the angular scales.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    Ultrahigh-energy neutrino follow-up of Gravitational Wave events GW150914 and GW151226 with the Pierre Auger Observatory

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    On September 14, 2015 the Advanced LIGO detectors observed their first gravitational-wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy above 100 PeV from point-like sources across the sky with equatorial declination from about -65 deg. to +60 deg., and in particular from a fraction of the 90% confidence-level (CL) inferred positions in the sky of GW150914 and GW151226. A targeted search for highly-inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth's crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within ±500\pm 500 s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. From the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter

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    An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is unchanged with respect to v2. 39 pages, 15 figures, 2 table

    Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger Observatory

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    The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ)max(\sec \theta)_\mathrm{max}, sensitive to the mass composition of cosmic rays above 3×10183 \times 10^{18} eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modelling that must be resolved before the mass composition can be inferred from (secθ)max(\sec \theta)_\mathrm{max}.Comment: Replaced with published version. Added journal reference and DO

    Operations of and Future Plans for the Pierre Auger Observatory

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    Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200
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