601 research outputs found

    Tiller Population Density and Sward Stability of Brachiaria brizantha Continuously Stocked by Cattle

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    Tiller population density is one the most important parameters of sward structure and its evaluation is normally included in studies of sward dynamics. Moreover, a greater level of understanding is achieved when the survival of successive tiller generations is monitored. (Matthew et al., 2000). This would help to explain seasonal variation in tiller populations based on tiller appearance and death rates. While Brachiaria brizantha c.v. Marandu occupies up to 70 million hectares of cultivated grassland in Brazil, little is known of its ecophysiology. The objective of this work was to calculate survival probability of B. brizantha tillers and identify seasonal variation on sward stability

    Estimação de componentes de variĂąncia e parĂąmetros genĂ©ticos para pesos do nascimento aos 196 dias de idade em ovinos Santa InĂȘs por meio de modelo multicaracterĂ­stica.

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    Resumo: O trabalho foi conduzido com o objetivo de estimar os componentes de variĂąncia e parĂąmetros genĂ©ticos para os pesos ao nascer, 56, 112 e 196 dias de idade em ovinos Santa InĂȘs por meio de um modelo animal em anĂĄlise multicaracterĂ­stica. O modelo de anĂĄlise inclui os efeitos aleatĂłrios genĂ©ticos aditivos direto e materno e de ambiente permanente materno. Os efeitos fixos utilizados na anĂĄlise foram os de grupo contemporĂąneo e idade da mĂŁe ao parto, como covariĂĄvel. As herdabilidades diretas estimadas para os pesos ao nascer, 56, 112 e 196 dias de idade foram, respectivamente, 0,17, 0,05, 0,08 e 0,10. Os resultados encontrados indicam que o ganho genĂ©tico obtido por meio de seleção individual serĂĄ pequeno. O efeito materno apresentou influĂȘncia sobre os pesos estudados. Variance components and genetics parameters estimation for birth weight to the 196-days in Santa InĂȘs sheep using multiple-trast model. Abstract: The study was carried out with the objective to stimate the variance components and genetics parameters for birth weights 56, 112 and 196-day in Santa InĂȘs sheep using multiple-trast animal model. The molysis model includes the direct additive and maternal genetic effect and permanent maternal environmental effect. The fixed effects used in molysis were the contemporary group and age of dam lombing, as (co)varience. The estimate direct heritability for the weights at the birth, 56, 112 and 196 days of age were 0,17, 0,05, 0,08 and 0,10 respectively. The found results indicate that the genetic gain obtained through individual selection it will be small. The maternal effect presented influence on the weights studied

    The growth pattern of brazilian Canela-Preta chickens with different plumages reared in two rearing systems.

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    Growth pattern is essential for economically efficient poultry production. In this study, we aimed to describe the growth curve of chickens of the Canela-Preta breed reared in two different rearing systems, considering their different plumage colors

    Caracterização física de diferentes cultivares de bananeira provenientes da Chapada do Apodi.

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    O nordeste brasileiro vem se tornando referĂȘncia para investimentos e para desenvolvimento da fruticultura tropical, contribuindo assim para melhoria das camadas mais pobres, com a geração de emprego e renda para uma população. A banana (Musa spp) Ă© uma das frutas mais consumidas do mundo. No Brasil acredita-se que as bananeiras existam, desde antes do seu descobrimento, segundo a FAO (2011) seu consumo chega a 31 kg/hb por ano. O Brasil, atualmente, dispĂ”e de uma ĂĄrea de mais 490 mil hectares plantados com bananeira, ficando em terceiro lugar em produção desta fruta (Mendonça & Mendonça, 2013)

    MARTA: A high-energy cosmic-ray detector concept with high-accuracy muon measurement

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    A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.Comment: 11 page

    ConsideraçÔes técnicas sobre o cruzamento de galinhas locais x linhagens comerciais.

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    A criação de galinhas caipiras (aves ?naturalizadas? ou localmente adaptadas), Ă© uma realidade em todo o Nordeste brasileiro, constituindo plantĂ©is presentes, em predominĂąncia de ocorrĂȘncia, nas unidades familiares. SĂŁo aves com caracterĂ­sticas genĂ©ticas, comportamento e conduzidas em manejo tradicional, que gradativamente vĂȘm incorporando medidas de biosseguridade, nutrição e sanidade, sem perder a ?identidade?, por apresentarem ciclo completo de reprodução. Essas caracterĂ­sticas sĂŁo transmitidas geneticamente para as geraçÔes seguintes. Encontra-se uma variabilidade genĂ©tica entre indivĂ­duos, pela rotação de reprodutores e particularidades de agrupamentos locais de aves, que nĂŁo estĂŁo vinculados Ă s granjas comerciais.bitstream/item/224453/1/Doc-271-Consideracoes-tecnicas-galinhas-locais.pd

    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

    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, (sec⁡ξ)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 (sec⁡ξ)max(\sec \theta)_\mathrm{max}.Comment: Replaced with published version. Added journal reference and DO

    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
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