Consequences of long-distance transport on the behavior and health of young-bulls that may affect their fitness to adapt to feedlots

Some studies have shown that long distance journeys and the type of trailer compartment have consequences on farm animal welfare. However, there is little evidence to indicate how these consequences affect the fitness of young bulls to adapt to a novel and challenging environment such as an intensive industrial feedlot. Therefore, the objective of our study was to evaluate the consequences of long-distance transport and trailer compartment on the behavior and health of young bulls during the first 60 days after arrival to the feedlot. An evaluation protocol was conducted to record individual behavior (scan sampling) and health indicators of young bulls from days 1-10 and 51-60 after arrival. In addition, three ocular thermal images were taken per animal in a chute during weighing, one each on day 0, day 2 (48 h) and day 50. From our results, the thermophysiological profile, maintenance behaviors and health indicators suggest that there are two distinct groups of consequences affecting animal fitness during the first two months in the feedlot. The first was linked to post-transport fatigue (PTF) that seemed to disappear after the 10 days post-arrival at feedlot. The second was related to signs of bovine respiratory disease (BRD) that began 6 days post-transport and persisted until day 60. In addition, the trailer compartments known as the belly and the deck were shown to be problematic for animal welfare, where the transport in the belly was linked to fatigue after transport, while transport in the deck was associated with respiratory problems. Our study underscores the importance of applying preconditioning practices in cow-calf rearing systems at least a couple of months prior to the long-distance journey, in addition to implementing good loading practices to select which animals are best suited for a given compartment. Our results may be useful to minimize the impacts of PTF and BRD, to propose best practices for livestock transport in countries with similar production systems and agroecosystems

On the sensitivity of the HAWC observatory to gamma-ray bursts

We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles

Oxygen consumption of Litopenaeus vannamei juveniles in heterotrophic medium with zero water exchange Consumo de oxigênio de juvenis de Litopenaeus vannamei em meio heterotrófico sem renovação de água

This work aimed at determining the dissolved oxygen consumption rate of Litopenaeus vannamei juveniles maintained in a microbial biofloc raceway system at high density with no aeration. Three 4 L bottles were filled for each treatment, sealed hermetically, and placed in an enclosed greenhouse raceway system. Four shrimp (13.2±1.42 g) were assigned to two sets of the bottles, which underwent the following treatments: light conditions with no shrimp; dark conditions with no shrimp; light conditions with shrimp; and dark conditions with shrimp. Dissolved oxygen content was measured every 10 min for 30 min. A quadratic behavior was observed in dissolved oxygen concentration over time. Significant differences for oxigen consumption were observed only at 10 and 20 min between shrimp maintained in the dark and those under light conditions. At 10 min, a higher value was observed in shrimp maintained under light, and at 20 min, in the dark. Significant differences between 10 and 20 min and between 10 and 30 min were observed when oxygen consumption was analyzed over time in the presence of light. Under dark conditions there were significant differences only between 20 and 30 min. Lethal oxygen concentration (0.65 mg L-1) would be reached in less than one hour either under light or dark conditions with no aeration.<br>O objetivo deste trabalho foi determinar o consumo de oxigênio dissolvido (OD) de juvenis de Litopenaeus vannamei mantidos em sistema de cultivo de bioflocs bacterianos em alta densidade e ausência de aeração. Três garrafas de 4 L foram preenchidas para cada tratamento, fechadas hermeticamente e colocadas em sistema de cultivo fechado. Quatro camarões (13,2±1,42 g) foram colocados em dois dos conjuntos de garrafas. Os tratamentos aplicados foram: luminosidade, sem camarões; escuro, sem camarões; luminosidade, com camarões; escuro, com camarões. A concentração de oxigênio dissolvido foi determinada a cada 10 min durante 30 min. Foi observado um comportamento quadrático na concentração de OD ao longo do tempo. Diferenças significativas para consumo de oxigênio foram observadas apenas aos 10 e 20 min entre camarões mantidos no escuro e camarões em luminosidade. Aos 10 min, foi observada maior concentração no sistema mantido em luminosidade e, aos 20 min, no sistema mantido no escuro. Na análise do consumo de oxigênio ao longo do tempo e com luminosidade, foram constatadas diferenças significativas entre 10 e 20 min e entre 10 e 30 min. Em condições de escuridão, houve diferença significativa apenas entre 20 e 30 min. Concluiu-se que, sem aeração, a condição anóxica pode ser alcançada em menos de uma hora, tanto ao dia quanto à noite

Carbon nanotubes as heat dissipaters in microelectronics

We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties of nanotubes in presence of an interface with various substances, including air and water. Comparison with previous works is established whenever is possible.Comment: 14 pages, 21 figures, 5 table