Efectos de la intensificación ganadera sobre la eficiencia en el uso de la energía fósil y la conservación del pastizal en la cuenca baja del río Salado, provincia de Buenos Aires, Argentina

Jacobo, Elizabeth J. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.Rodríguez, A. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.González, J. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.Golluscio, Rodolfo Angel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.1-14Con el objetivo de explorar las consecuencias sobre la sustentabilidad ambiental del proceso de intensificación de la ganadería bovina de la cuenca del Salado, se comparó la proporción y condición del pastizal natural, la cantidad de energía fósil consumida por unidad de superficie y de producto y la eficiencia en el uso de energía fósil de13 establecimientos con distinta intensidad en el uso de insumos para la alimentación del ganado. La energía fósil consumida por unidad de superficie mostró un rango entre 600 y 3600 MJ hectárea-1 año-1, la consumida por unidad de producto se ubicó entre 0,01 y 8,49 MJ kg-1 de peso vivo de carne bovina y la eficiencia en el uso de energía resultó entre 0,92 y 1973 MJ producidos por MJ consumidos. El consumo de energía fue inferior y la eficiencia en su uso fue superior en los establecimientos que conservan una elevada proporción de pastizal en buena condición, como consecuencia del adecuado manejo del pastoreo respecto de la de aquellos que usaron mayor cantidad de insumos para la alimentación. El actual proceso de intensificación está disminuyendo la eficiencia energética de los sistemas de producción de carne, lo que sugiere una alerta para la sustentabilidad ambiental

Vortex phases in superconducting Nb thin films with periodic pinning

Magnetotransport properties have been used to investigate vortex phases in Nb films with periodic arrays of magnetic pinning centers. This kind of samples show a continuous glass transition similar to that observed in Nb plain films, but the periodic pinning yields different critical exponents and enhanced glass transition temperature at the matching field

Efectos de la intensificación ganadera sobre la eficiencia en el uso de la energía fósil y la conservación del pastizal en la cuenca baja del río Salado, provincia de Buenos Aires, Argentina

Jacobo, Elizabeth J. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.Rodríguez, A. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.González, J. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.Golluscio, Rodolfo Angel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Buenos Aires, Argentina.1-14Con el objetivo de explorar las consecuencias sobre la sustentabilidad ambiental del proceso de intensificación de la ganadería bovina de la cuenca del Salado, se comparó la proporción y condición del pastizal natural, la cantidad de energía fósil consumida por unidad de superficie y de producto y la eficiencia en el uso de energía fósil de13 establecimientos con distinta intensidad en el uso de insumos para la alimentación del ganado. La energía fósil consumida por unidad de superficie mostró un rango entre 600 y 3600 MJ hectárea-1 año-1, la consumida por unidad de producto se ubicó entre 0,01 y 8,49 MJ kg-1 de peso vivo de carne bovina y la eficiencia en el uso de energía resultó entre 0,92 y 1973 MJ producidos por MJ consumidos. El consumo de energía fue inferior y la eficiencia en su uso fue superior en los establecimientos que conservan una elevada proporción de pastizal en buena condición, como consecuencia del adecuado manejo del pastoreo respecto de la de aquellos que usaron mayor cantidad de insumos para la alimentación. El actual proceso de intensificación está disminuyendo la eficiencia energética de los sistemas de producción de carne, lo que sugiere una alerta para la sustentabilidad ambiental

Fully 3D GPU PET reconstruction

Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit(GPU) has be enproposed formany years as potential accelerators incomplex scientific problems, but it has not be enuseduntil there cent advances in the programmability of GPU sthat the best available reconstruction code shave started tobe implemented toberunon GPUs. This work presents a GPU based fully 3D PET iterative reconstruction sofware. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time consuming part soft he code,the forward and backward projection operations, arebasedonan accurate model of the scanner obtained with the MonteCarlo code PeneloPET and they have been massively parallelize don the GPU.For the PET scanners considered, the GPU based code is more than 70 times faster than asimilar code running on a single core of a fast CPU, obtainingin both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.This work has been supported by MEC(FPA200762216), UCM (Grupos UCM,910059), CPAN(Consolider Ingenio 2010) CSPD 200700042,the RECAVARETIC network, ARTEMISS2009/ DPI 1802, European Regional Development,ENTEPRASE grant, PSE 30000020095 and TEC20080675C0201, Ministerio de Ciencia e Innovación, Spanish Government.Publicad

Positron range effects in high resolution 3D PET imaging

Proceeding of: 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), Orlando, Florida, 25-31 October 2009Positron range limits the spatial resolution of PET images. It has a different effect for different isotopes and propagation materials, therefore it is important to consider it during image reconstruction, in order to obtain the best image quality. Positron range distribution was computed using Monte Carlo simulations with PeneloPET. The simulation models positron trajectories and computes the spatial distribution of the annihilation coordinates for the most common isotopes used in PET: 18F, 11C, 13N, 15O, 68Ga and 82Rb. Range profiles are computed for different positron propagation materials, obtaining one kernel profile for each isotope-material combination. These range kernels were introduced in FIRST, a 3D-OSEM image reconstruction software, and employed to blur the object during forward projection. The blurring introduced takes into account the material in which the positron is annihilated, obtained for instance from a CT image. In this way, different positron range corrections for each material in the phantom are considered. We compare resolution and noise properties of the images reconstructed with and without positron range modelling. For this purpose, acquisitions of an Image Quality phantom filled with different isotopes have been simulated for the ARGUS small animal PET scanner.This work has been supported in part by MEC (FPA2007 62216), CDTEAM (Programa CENIT, Ministerio de Industria), UCM (Grupos UCM, 910059), CPAN (Consolider Ingenio 2010) CSPD 2007 00042 and the RECAVA RETIC network. Part of the calculations of this work were performed in the “Clúster de Cálculo de Alta Capacidad para Técnicas Físicas” funded in part by UCM and in part by UE under FEDER programme”

Validation of peneloPET positron range estimations

Proceeding of: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE), Knoxville, Tennessee, USA, October 30 - November 6, 2010Positron range depends on the materials in which positron propagates and on positron emitter isotope. As positron range limits the spatial resolution of PET images, good quantitative estimates of it should be included in any realistic simulation of PET acquisitions. In this work we compare positron range estimates obtained with PeneloPET to previous available simulations and experimental data. PeneloPET was used to simulate the positron range of 18F, 11C, 13N, 15O, 68Ga and 82Rb in the following tissues: cortical bone, soft bone, skin, muscle, brain, water, adipose tissue and lung. The 3D and 1D annihilation Point Spread Functions (aPSF) were calculated for each isotope-material combination. We have studied with more detail the 3D aPSF (radial distributions) and the cumulative fraction of annihilation events. These aPSF distributions were also studied for non-uniform media. Results obtained were consistent with other results previously reported in the literature as well as with experimentally measured data.This work has been supported by MEC (FPA2007-62216), UCM (Grupos UCM, 910059), CPAN (Consolider- Ingenio 2010) CSPD-2007-00042, European Regional Development and ENTEPRASE grant, PSE-300000-2009-5, and the CENIT program project AMIT, Ministerio de Ciencia e Innovación, Spanish Government. Part of the calculations of this work were performed in the “Clúster de Cálculo de Alta Capacidad para Técnicas Físicas” funded in part by UCM and in part by UE under FEDER programme”.Publicad

Positron range estimations with PeneloPET

Technical advances towards high resolution PET imaging try to overcome the inherent physical limitations to spatial resolution. Positrons travel in tissue until they annihilate into the two gamma photons detected. This range is the main detector-independent contribution to PET imaging blurring. To a large extent, it can be remedied during image reconstruction if accurate estimates of positron range are available. However, the existing estimates differ, and the comparison with the scarce experimental data available is not conclusive. In this work we present positron annihilation distributions obtained from Monte Carlo simulations with the PeneloPET simulation toolkit, for several common PET isotopes (18F, 11C, 13N, 15O, 68Ga and 82Rb) in different biological media (cortical bone, soft bone, skin, muscle striated, brain, water, adipose tissue and lung). We compare PeneloPET simulations against experimental data and other simulation results available in the literature. To this end the different positron range representations employed in the literature are related to each other by means of a new parameterization for positron range profiles. Our results are generally consistent with experiments and with most simulations previously reported with differences of less than 20% in the mean and maximum range values. From these results, we conclude that better experimental measurements are needed, especially to disentangle the effect of positronium formation in positron range. Finally, with the aid of PeneloPET, we confirm that scaling approaches can be used to obtain universal, material and isotope independent, positron range profiles, which would considerably simplify range correction.We kindly acknowledge support from Comunidad de Madrid (ARTEMIS S2009/DPI-1802), Spanish Ministry of Science and Innovation (grants FPA2010-17142 and ENTEPRASE, PSE-300000-2009-5), by European Regional Funds, by CDTI under the CENIT Programme (AMITProject) and by CPAN, CSPD-2007-00042@Ingenio2010. Part of the calculations of this work were performed in the “Cluster de Cálculo de Alta Capacidad para Técnicas Físicas” funded in part by UCM and in part by UE under FEDER programme. This is a contribution to the Campus of International Excellence of MoncloaPublicad

Isokinetic leg strength and power in elite handball players

Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60º/s and 180º/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60º/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180º/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60º/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180º/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.Actividad Física y Deport

Interface barriers for flux motion in high-temperature superconducting superlattices

We study angular dependent magnetoresistance in the vortex-liquid phase of epitaxial YBa2Cu3O7 thin films and YBa_2Cu_3O_7/PrBa_2Cu_3O_7 superlattices. Superlattices were grown with different PrBa_2Cu_3O_7 thickness in order to tune coupling between YBa_2Cu_3O_7 layers. While dissipation of single film and coupled superlattices is scaled with the anisotropic three-dimensional model in the whole angular range, decoupling through PrBa_2Cu_3O_7 spacer breaks down the scaling and yields strong reduction of the dissipation when the magnetic fields are applied up to ±20degrees around the interface direction. Bean-Livingston barriers at the interface are the mechanism which governs this behavior

Study of CT-based positron range correction in high resolution 3D PET imaging

Positron range limits the spatial resolution of PET images and has a different effect for different isotopes and positron propagationmaterials. Therefore it is important to consider it during image reconstruction, in order to obtain optimal image quality. Positron range distributions for most common isotopes used in PET in different materials were computed using the Monte Carlo simulations with PeneloPET. The range profiles were introduced into the 3D OSEM image reconstruction software FIRST and employed to blur the image either in the forward projection or in the forward and backward projection. The blurring introduced takes into account the different materials in which the positron propagates. Information on these materials may be obtained, for instance, from a segmentation of a CT image. The results of introducing positron blurring in both forward and backward projection operations was compared to using it only during forward projection. Further, the effect of different shapes of positron range profile in the quality of the reconstructed images with positron range correction was studied. For high positron energy isotopes, the reconstructed images show significant improvement in spatial resolution when positron range is taken into account during reconstruction, compared to reconstructions without positron range modeling.This work has been supported by the MEC (FPA2007 62216), the UCM (Grupos UCM, 910059), the CPAN (Consolider Ingenio 2010) CSPD 2007 00042, the RECAVA RETIC network, ARTEMIS S2009/ DPI 1802, the European Regional Development and ENTEPRASE grant, PSE 300000 2009 5 and the Ministerio de Ciencia e Innovación, Spanish Government.Publicad