4,186 research outputs found

    Extra polarization states of cosmological gravitational waves in alternative theories of gravity

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    Cosmological Gravitational Waves (GWs) are usually associated with the transverse-traceless part of the metric perturbations in the context of the theory of cosmological perturbations. These modes are just the usual polarizations `+' and `x' which appear in the general relativity theory. However, in the majority of the alternative theories of gravity, GWs can present more than these two polarization states. In this context, the Newman-Penrose formalism is particularly suitable for evaluating the number of non-null GW modes. In the present work we intend to take into account these extra polarization states for cosmological GWs in alternative theories of gravity. As an application, we derive the dynamical equations for cosmological GWs for two specific theories, namely, a general scalar-tensor theory which presents four polarization states and a massive bimetric theory which is in the most general case with six polarization states for GWs. The mathematical tool presented here is quite general, so it can be used to study cosmological perturbations in all metric theories of gravity.Comment: 26 pages, 1 figure. Accepted for publication in Classical and Quantum Gravity

    Photoinduced intersubband transition in undoped HgCdTe multiple quantum wells

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    We present photoinduced intersubband absorption measurements in HgCdTe undoped quantum wells. The transition energies and the linewidths are well described by a full 8×8 k⋅p Kane model calculation. Also, based on this model we show that different in‐plane effective masses for the first and second electron subbands should be considered in order to properly fit the low energy side of the experimental spectra. The experimental results can be explained using the calculated intersubband oscillator strength with no exciton enhancement. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69671/2/APPLAB-66-22-2998-1.pd

    Perfil sanitário de rebanhos ovinos e caprinos da Microrregião do Alto Médio Gurguéia, no Sul do estado do Piauí, Brasil.

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    Resumo: Objetivou-se caracterizar o perfil sanitário de rebanhos caprinos e ovinos na Microrregião do Alto Médio Gurguéia, sul do estado do Piauí. Foi aplicado questionário em 53 unidades produtoras. O manejo sanitário, características das instalações e sinais clínicos das enfermidades foram descritas. Verificou-se que 92,4% dos rebanhos foram acondicionados em ?chiqueiros?. A higiene diária das instalações era realizada em 1,9% das propriedades e 13,2% não adotavam higiene sanitária alguma. A vermifugação foi a prática mais difundida (94,3%) e os principais achados clínicos foram sugestivos de doenças infecciosas e parasitárias. Conclui-se que o manejo sanitário tem sido empregado de forma inadequada, com a manifestação de sinais clínicos que podem decorrer de enfermidades peculiares a caprino e ovinocultura. Abstract: This study aimed to characterize the health profile of goats and sheep herds in the High Middle Gurguéia micro-region, the southern state of Piaui. A questionnaire was applied at 53 farms. The health management, animal facilities and clinical signs of disease were described. The results showed that 92.4% of the herds were kept in "sty". Daily hygiene of the animal facilities was carried out at 1.9% and 13.2% of farms did not adopt any health care. The worming practice was more widespread (94.3%) and the main clinical findings were suggestive of infectious and parasitic diseases. We conclude that the health management has been used inappropriately, with manifestation of clinical signs that may result from diseases peculiar to goat and sheep industr

    Field evaluation of Bt cotton crop impact on nontarget pests: cotton aphid and boll weevil.

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    Made available in DSpace on 2018-07-01T01:26:24Z (GMT). No. of bitstreams: 1 art3A10.10072Fs1374401200940.pdf: 255052 bytes, checksum: 0eecda39292292a10208a82621fb821b (MD5) Previous issue date: 2013-08-13bitstream/item/156260/1/art3A10.10072Fs13744-012-0094-0.pd

    Performance of the safer model in estimating actual evapotranpiration of wheat an bean irrigated crops in the Central Brazillian savannah.

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    O atendimento da demanda crescente por alimentos depende diretamente da irrigação. Neste cenário, o manejo eficiente dos recursos hídricos e o entendimento da variação temporal e espacial da evapotranspiração real das culturas (ETa) é essencial. Nas últimas décadas, modelos para monitoramento e mapeamento da ETa usando dados de sensoriamento remoto foram desenvolvidos. Neste trabalho, a performance do modelo Simple Algorithm for Evapotranspiration Retrieving (SAFER) foi avaliada para estimativa da evapotranspiração de duas culturas anuais irrigadas de inverno, no Cerrado. Para tal, utilizaram-se imagens multiespectrais e termais dos sensores ETM+/Landsat 7 e OLI-TIRS/Landsat 8. Inicialmente, o modelo foi calibrado para o trigo, sendo testado em seguida para o feijão, utilizando como referência dados de ETa obtidos pelo método da razão de Bowen. Após a calibração, o coeficiente de determinação (r²) encontrado foi igual a 0,91 e a raiz do erro quadrático médio (RMSE) igual a 0,58 mm d-1, para o trigo. Para o feijão, o r² foi igual a 0,65 e a RMSE igual a 0,77 mm d-1. Os resultados são satisfatórios, porém, sugerem que uma performance melhor pode ser obtida ao adotar-se uma calibração específica por cultura e/ou região, ou uma calibração em dois estágios, para valores de NVDI baixos e altos

    Preparation and control of a cavity-field state through atom-driven field interaction: towards long-lived mesoscopic states

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    The preparation of mesoscopic states of the radiation and matter fields through atom-field interactions has been achieved in recent years and employed for a range of striking applications in quantum optics. Here we present a technique for the preparation and control of a cavity mode which, besides interacting with a two-level atom, is simultaneously submitted to linear and parametric amplification processes. The role of the amplification-controlling fields in the achievement of real mesoscopic states, is to produce highly-squeezed field states and, consequently, to increase both: i) the distance in phase space between the components of the prepared superpositions and ii) the mean photon number of such superpositions. When submitting the squeezed superposition states to the action of similarly squeezed reservoirs, we demonstrate that under specific conditions the decoherence time of the states becomes independent of both the distance in phase space between their components and their mean photon number. An explanation is presented to support this remarkable result, together with a discussion on the experimental implementation of our proposal. We also show how to produce number states with fidelities higher than those derived as circular states

    Restricted intake and lipid inclusion in Santa Inês ewe lambs diet: age, weight and progesterone concentration at first ovulation.

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    Abstract: The age at first ovulation is influenced by several factors, and nutrition has an essential role on it. Lipids provide essential fatty acids that are positively associated to reproductive aspects. The aims of this study were to evaluate the effects of lipid inclusion and restricted intake on age and weight at the first ovulation and the serum progesterone (P4) concentration at the sixth day after first ovulation. Thirty-five Santa Inês ewe lambs with initial body weight (BW) of 21.5 ± 0.3 kg and age of 91.6 ± 1.4 days were used. Animals were blocked according to initial BW and distributed to one of four treatments: animals receiving diet without lipid inclusion (3.5% ether extract ? EE), ad libitum intake (WLI-ALI, control group, n = 9); diet without lipid inclusion and restricted intake (WLI-RI, n = 9); lipid inclusion diet, represented by toasted and broken soybean (9.8% EE), ad libitum intake (LIP-ALI, n = 8); and lipid inclusion diet and restricted intake (LIP-RI, n = 9). Ewe lambs subjected to restricted intake had 84% of the diet offered to those in ad libitum treatments. The individual daily dry matter intake (DMI) and EE intake (EEI) were measured and the animals were weekly weighted until 35 kg BW. For P4 analysis, blood samples were collected once a week after the animals reached 25 kg BW and twice a week after 30 kg until 35 kg BW. Ovulation was estimated to occur on the sixth day before P4 ?1 ng/mL. DMI, EEI, average daily weight gain until first ovulation (DWG), weight and age at first ovulation, serum P4 concentration and days in experiment until first ovulation were analyzed by GLM PROC of the SAS software (version 9.3). Ovulation occurred in 60% (21/35) of the ewe lambs (5; 5; 6; 5 from WLI-ALI; WLI-RI; LIP-ALI; and LIP-RI, respectively). DMI of ewe lambs from WLI-ALI group was greater (P 0.05) among WLI-ALI, WLI-RI, LIP-ALI, and LIP-RI treatments, respectively. The first ovulation in Santa Inês ewe lambs occurs at 30 kg BW. The restricted intake imposed in this study did not delay the age at fist ovulation. The greater lipid intake did not favor reproductive parameters. Serum P4 did not increase with the soybean inclusion in the diet. [Restrição alimentar e suplementação lipídica: idade, peso e concentração de progesterona até a primeira ovulação]. Resumo: A idade da primeira ovulação é influenciada por vários fatores e a nutrição tem um papel essencial. Lipídios fornecem ácidos graxos essenciais que estão associados de forma positiva aos aspectos reprodutivos. Os objetivos deste estudo foram avaliar os efeitos da inclusão lipídica e da restrição do consumo na idade e peso a primeira ovulação e na concentração sérica de progesterona (P4) no sexto dia após a primeira ovulação. Foram utilizadas trinta e cinco cordeiras Santa Inês com peso corporal (PC) inicial de 21,5±0,3 kg e idade de 91,6±1,4 dias. Os animais foram blocados de acordo com o PC inicial e distribuído a um dos quatro tratamentos: animais que receberam dieta sem inclusão de lipídeos (3,5% de extrato etéreo - EE), consumo ad libitum (SEM-ALI, grupo controle, n=9); dieta sem inclusão de lipídeos e restrição do consumo (SEMRE, n=9); dieta com inclusão lipídica, representada pela soja tostada e quebrada (9,8% EE), consumo ad libitum (LIP-ALI, n=8); e dieta com inclusão lipídica e restrição do consumo (LIP-RE, n=9). Cordeiras submetidas a restrição do consumo tiveram 84% da dieta oferecida em comparação aos tratamentos ad libitum. O consumo individual diário de matéria seca (CMS) e de EE (CEE) foram mensurados e os animais foram pesados semanalmente até 35 kg de PC. Para a análise de P4, amostras de sangue foram coletadas uma vez por semana depois que os animais atingiram 25 kg de PC e duas vezes por semana após 30 kg até 35 kg de PC. Estimou-se que a ovulação ocorreu no sexto dia que antecedeu P4?1 ng/mL. CMS, CEE, ganho de peso médio diário até a primeira ovulação (GPD), peso e idade da primeira ovulação, a concentração sérica de P4 e dias em experimento até a primeira ovulação foram analisados pelo PROC GLM do software SAS (versão 9.3). A ovulação ocorreu em 60% (21/35) das cordeiras (5; 5; 6; 5 do SEM-ALI; SEM-RE; LIP-ALI e LIP-RE, respectivamente). CMS de cordeiras do grupo SEM-ALI foi maior (P0,05) entre os tratamentos SEM-ALI, SEM-RE, LIP-ALI e LIP-RE, respectivamente. A primeira ovulação em borregas Santa Inês ocorreu com 30 kg de PC. A restrição do consumo imposta neste estudo não retardou a idade a primeira ovulação. A maior ingestão de lipídios não favoreceu os parâmetros reprodutivos. A P4 sérica não aumentou com a inclusão de soja na dieta.Proceedings of the 30th Annual Meeting of the Brazilian Embryo Technology Society (SBTE); Foz do Iguaçu, PR, Brazil, August 25th to 27th, 2016, and 32nd Meeting of the European Embryo Transfer Association (AETE); Barcelona, Spain, September 9th and 10th, 2016

    Estudo retrospectivo das principais complicações durante a anestesia geral inalatória em cães

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    Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

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    New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure
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