43 research outputs found

    Effect of natural zeolite on live weight changes, ruminal fermentation and nitrogen metabolism of ewe lambs

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    The objective of this study was to evaluate the effects of natural zeolite on the performance and nitrogen metabolism of Rambouillet ewe lambs. Forty Rambouillet ewe lambs with an initial weight of 41.06 ± 3.9 kg were randomly assigned to one of four experimental diets, namely 0, 20, 40 and 60 g of natural zeolite (Comercializadora Omega® México) per kg dietary dry matter in a completely randomized design and sixteen ewe lambs were used in a 4 x 4 Latin square metabolism study. Performance was not modified by natural zeolite levels in the diet, and daily gain showed a quadratic response. Ammonia concentration at 8 and 12 hours increased linearly with zeolite. Zeolite increased ruminal pH linearly at 8 and 12 hours. Acetate and butyrate presented a quadratic response, and total ruminal volatile fatty acid concentration was linearly increased by zeolite. Nitrogen retention showed a linear and quadratic response to zeolite. The estimated fractions of protein digested in the small intestine, when rumen-fermentable energy was limiting (PDIE) and when rumen-fermentable nitrogen was limiting, showed a linear and quadratic response to zeolite. PDIE was positively correlated (r = 0.96) with average daily gain.Keywords: Sheep, ammonium, ruminal fermentation, productive, soluble nitroge

    Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

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    Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{6×10196\times 10^{19}eV}. The anisotropy was measured by the fraction of arrival directions that are less than 3.13.1^\circ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron 12th12^{\rm th} catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (386+7)(38^{+7}_{-6})%, compared with 2121% expected for isotropic cosmic rays. This is down from the early estimate of (6913+11)(69^{+11}_{-13})%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201

    Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

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    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius AA. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

    Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory

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    The advent of the Auger Engineering Radio Array (AERA) necessitates the development of a powerful framework for the analysis of radio measurements of cosmic ray air showers. As AERA performs "radio-hybrid" measurements of air shower radio emission in coincidence with the surface particle detectors and fluorescence telescopes of the Pierre Auger Observatory, the radio analysis functionality had to be incorporated in the existing hybrid analysis solutions for fluoresence and surface detector data. This goal has been achieved in a natural way by extending the existing Auger Offline software framework with radio functionality. In this article, we lay out the design, highlights and features of the radio extension implemented in the Auger Offline framework. Its functionality has achieved a high degree of sophistication and offers advanced features such as vectorial reconstruction of the electric field, advanced signal processing algorithms, a transparent and efficient handling of FFTs, a very detailed simulation of detector effects, and the read-in of multiple data formats including data from various radio simulation codes. The source code of this radio functionality can be made available to interested parties on request.Comment: accepted for publication in NIM A, 13 pages, minor corrections to author list and references in v

    Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory

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    We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5×10172.5\times 10^{17} eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L.C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.Comment: 28 pages, 11 figure

    Depth Of Maximum Of Air-shower Profiles At The Pierre Auger Observatory. I. Measurements At Energies Above 1017.8ev

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    Measurement of the double-differential high-mass Drell-Yan cross section in pp collisions at √s = 8 TeV with the ATLAS detector

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    This paper presents a measurement of the double-differential cross section for the Drell-Yan Z/γ∗ → ℓ+ℓ− and photon-induced γγ → ℓ+ℓ− processes where ℓ is an electron or muon. The measurement is performed for invariant masses of the lepton pairs, mℓℓ, between 116 GeV and 1500 GeV using a sample of 20.3 fb−1 of pp collisions data at centre-of-mass energy of √s = 8 TeV collected by the ATLAS detector at the LHC in 2012. The data are presented double differentially in invariant mass and absolute dilepton rapidity as well as in invariant mass and absolute pseudorapidity separation of the lepton pair. The single-differential cross section as a function of mℓℓ is also reported. The electron and muon channel measurements are combined and a total experimental precision of better than 1% is achieved at low mℓℓ. A comparison to next-to-next-to-leading order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading order electroweak effects indicates the potential of the data to constrain parton distribution functions. In particular, a large impact of the data on the photon PDF is demonstrated

    Gillnet catch composition in Bahia de Navidad, Jalisco, Mexico [Composicion especifica de la captura con redes de enmalle en Bahia de Navidad, Jalisco, Mexico]

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    Catch composition and species relative importance (in weight and number of individuals) was analyzed from catch surveys using gillnets in Bahia Navidad, on the central Pacific coast of Mexico. Catch was sampled monthly from April 1994 to March 1995. Seventy five species were found, but most of them during a short period; fifty five during six months or less, and 29 in three months or less. Most species represent less than 2% of total catch in weight and numbers; ten species were dominant, the most important being Microlepidotus brevipinnis (26.5% in number, 18.5% in weight), Lutjanus guttatus (11.5% and 9.3%), Haemulon flaviguttatum (9.7% and 7.0%) and Caranx caballus (8.2% and 10.2%). A group of 16 species were present in more than eight months and were considered as the basis of the fish species association accessible to gillnets in the study area

    Gillnet catch composition in Bahia de Navidad, Jalisco, Mexico [Composicion especifica de la captura con redes de enmalle en Bahia de Navidad, Jalisco, Mexico]

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    Catch composition and species relative importance (in weight and number of individuals) was analyzed from catch surveys using gillnets in Bahia Navidad, on the central Pacific coast of Mexico. Catch was sampled monthly from April 1994 to March 1995. Seventy five species were found, but most of them during a short period; fifty five during six months or less, and 29 in three months or less. Most species represent less than 2% of total catch in weight and numbers; ten species were dominant, the most important being Microlepidotus brevipinnis (26.5% in number, 18.5% in weight), Lutjanus guttatus (11.5% and 9.3%), Haemulon flaviguttatum (9.7% and 7.0%) and Caranx caballus (8.2% and 10.2%). A group of 16 species were present in more than eight months and were considered as the basis of the fish species association accessible to gillnets in the study area

    Size composition and reproductive cycle of Pseudupeneus grandisquamis (Pisces: Mullidae) in the Central Mexican Pacific [Composición por tallas y ciclo reproductivo de Pseudupeneus grandisquamis (Pisces: Mullidae) en el Pacífico central Mexicano]

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    From June 1995 to December 1998 we used shrimp trawl nets to capture 492 Pseudupeneus grandisquamis in soft-bottom grounds off the central Mexican Pacific (Jalisco and Colima). The ength-weight ratio indicates allometric growth (p = 0.0035L3.46 y r2=0.97). The total sex ratio was 1:1.15 (females: males). Mean total length was 153.8 mm (range 77-236 mm). A progression in length was found: the highest means were observed at the end of 1996 and during 1997. The mean length of females (162 mm) was longer than in males (150 mm). Four gonadic maturity stages were observed in both sexes; in females the most frequently stage was stage IV (mature gonads, 48.6%), while in males it was stage III (gonads in maturation, 45.0 %). Seven microscopic oocyte development stages were identified. Oocyte development seems to be asynchronous. The mature testicle showed sperm inside the lobular lumen and in the duct. The highest values of the gonadosomatic index, as well as the largest percentages of individuals with mature gonads (at macroscopic and microscopic levels), were observed during winter and summer, suggesting that this species has two reproduction peaks by year. The length at which 50% of the individuals show gonads in maturation (L50) was 183 mm for the females and 181 mm for the males
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