1,022 research outputs found

    Coherent states on the circle

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    We present a possible construction of coherent states on the unit circle as configuration space. In our approach the phase space is the product Z x S^1. Because of the duality of canonical coordinates and momenta, i.e. the angular variable and the integers, this formulation can also be interpreted as coherent states over an infinite periodic chain. For the construction we use the analogy with our quantization over a finite periodic chain where the phase space was Z_M x Z_M. Properties of the coherent states constructed in this way are studied and the coherent states are shown to satisfy the resolution of unity.Comment: 7 pages, presented at GROUP28 - "28th International Colloquium on Group Theoretical Methods in Physics", Newcastle upon Tyne, July 2010. Accepted in Journal of Physics Conference Serie

    An experimental model of mixing processes generated by an array of top-heavy turbulent plumes

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    The mixing process of two fluids of unequal density generated by the evolution of an array of forced turbulent plumes is studied in the laboratory. The corresponding qualitative conclusions and the quantitative results based on measures of the density field and of the height of the fluid layers are described. The partial mixing process is characterized and analyzed, and the conclusions of this analysis are related to the mixing efficiency and the volume of the final mixed layer as functions of the Atwood number, which ranges from 0.010 to 0.134. An exponential fit is used to evaluate the mixing efficiency versus the Atwood showing the role of initial conditions on mixing efficiency variability

    Electric and magnetic dipolar response of Germanium spheres: Interference effects, scattering anisotropy and optical forces

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    We address the scattering cross sections, and their consequences, for submicrometer Germanium spheres. It is shown that there is a wide window in the near infrared where light scattering by these particles is fully described by their induced electric and magnetic dipoles. In this way, we observe remarkable anisotropic scattering angular distributions, as well as zero forward or backward scattered intensities, which until recently was theoretically demonstrated only for hypothetically postulated magnetodielectric spheres. Also, interesting new effects of the optical forces exerted on these objects are now obtained.Comment: 13 pages, 4 figure

    Thorpe method applied to planetary boundary layer data

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    Turbulence affects the dynamics of atmospheric processes by enhancing the transport of mass, heat, humidity and pollutants. The global objective of our work is to analyze some direct turbulent descriptors which reflect the mixing processes in the atmospheric boundary layer (ABL). In this paper we present results related to the Thorpe displacements dT , the maximum Thorpe displacement (dT )max and the Thorpe scale LT , the Ozmidov scale and their time evolution in the ABL during a day cycle. A tethered balloon was used to obtain vertical profiles of the atmospheric physical magnitudes up to 1000m. We discuss the vertical and horizontal variability and how different descriptors are related to atmospheric mixing

    Neurexin Dysfunction in Adult Neurons Results in Autistic-like Behavior in Mice

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    Autism spectrum disorders (ASDs) comprise a group of clinical phenotypes characterized by repetitive behavior and social and communication deficits. Autism is generally viewed as a neurodevelopmental disorder where insults during embryonic or early postnatal periods result in aberrant wiring and function of neuronal circuits. Neurexins are synaptic proteins associated with autism. Here, we generated transgenic βNrx1δC mice in which neurexin function is selectively impaired during late postnatal stages. Whole-cell recordings in cortical neurons show an impairment of glutamatergic synaptic transmission in the βNrx1δC mice. Importantly, mutant mice exhibit autism-related symptoms, such as increased self-grooming, deficits in social interactions, and altered interaction for nonsocial olfactory cues. The autistic-like phenotype of βNrx1δC mice can be reversed after removing the mutant protein in aged animals. The defects resulting from disruption of neurexin function after the completion of embryonic and early postnatal development suggest that functional impairment of mature circuits can trigger autism-related phenotypes. © 2014 The Authors.Research at the F.G.S. lab was funded by grants from NEURON-ERANET (EUHF-AUTISM, PIM2010ERN-0070), Instituto de Salud Carlos III (PI111058), and Junta de Andalucía (P11-CVI-7599). We thank Dr. Leon Lagnado (University of Sussex) for the generous gift of the sypHy construct, Dr. Oscar Pintado for pronuclear injection, Dr. Angel Barco for helpful advice with bitransgenic mice, and Dr. Maria Luz Montesinos and Itziar Benito for assistance with some behavioral tests. Technical assistance during the generation of transgenic mice was provided by María Luisa Pecero. The authors wish to thank Drs. Rafael Fernández-Chacón and Amalia Martinez-Mir for support and critical reading of the manuscript. E.R-L received a fellowship from V Plan Propio de Investigación (Universidad de Sevilla), and J.L.N.-G is a recipient of a Juan de la Cierva MINECO contract. Part of the study was performed at CITIUS (Universidad de Sevilla).Peer Reviewe

    Exploiting graphic processing units parallelism to improve intelligent data acquisition system performance in JET's correlation reflectometer

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    The performance of intelligent data acquisition systems relies heavily on their processing capabilities and local bus bandwidth, especially in applications with high sample rates or high number of channels. This is the case of the self adaptive sampling rate data acquisition system installed as a pilot experiment in KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. In order to do so it must transfer acquired data to a memory buffer in the host processor and run heavy computational algorithms for each data block. The processing capabilities of the host CPU and the bandwidth of the PXI bus limit the maximum sample rate that can be achieved, therefore limiting the maximum bandwidth of the phenomena that can be studied. Graphic processing units (GPU) are becoming an alternative for speeding up compute intensive kernels of scientific, imaging and simulation applications. However, integrating this technology into data acquisition systems is not a straight forward step, not to mention exploiting their parallelism efficiently. This paper discusses the use of GPUs with new high speed data bus interfaces to improve the performance of the self adaptive sampling rate data acquisition system installed on JET. Integration issues are discussed and performance evaluations are presente

    Modelo experimental de colocación de catéter intratecal lumbar para anestesia espinal en perros

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    Aunque existe controversia entre Corning y Bier, el primer caso de anestesia espinal se publica en el año 1885, cuando Cornig, accidentalmente, realiza un bloqueo espinal en un perro con cocaína. Desde entonces, la anestesia espinal probablemente ha sido la técnica regional más comúnmente utilizada en la moderna anestesia. Aunque se ha escrito mucho en lo relativo a dicha técnica: aplicaciones, complicaciones..., son pocos los estudios controlados, particularmente en animales donde ha sido posible mantener unas condiciones experimentales estandarizadas. Aún así, han sido descritos métodos experimentales de anestesia espinal 6-11 y epidural12-19 usando la implantación de catéteres en el perro, gato, oveja, rata y humanos. En la gran mayoría de los casos el acceso al espacio subaracnoideo se realiza quirúrgicamente vía occipital (se ha hecho en otras especies como en rata), llegando hasta la cisterna magna, donde puede quedar colocado el catéter, o bien prolongarlo hasta nivel torácico, lumbar. El presente estudio describe un modelo de implantación de catéter intradural en perros, con abordaje lumbar, con técnica quirúrgica previa y con control radioscópico

    A quantitative analysis of cold water for human consumption in hospitals in Spain

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    An estimation of the water used for human consumption in hospitals is essential to determine possible savings and to fix criteria to improve the design of new water consumption models.The present work reports on cold water for human consumption (CWHC) in hospitals in Spain and determines the possible savings. In the period of 2005–2012, 80 Eco-Management and Audit Schemes (EMAS) from20 hospitals were analysed. The results conclude that the average annual consumption of CWHC is 1.59m3/m2 (with a standard deviation of 0.48 m3/m2), 195.85 m3/bed (standard deviation 70.07 m3/bed), or 53.69 m3/worker (standard deviation 16.64 m3/worker). The results demonstrate the possibility of saving 5,600,000m3 of water per year. Assuming the cost of water as approximately 1.22 €/m3, annual savings are estimated as 6,832,000 €. Furthermore, 2,912MWh of energy could be saved, and the emission of 22,400 annual tonnes of CO2 into the atmosphere could be avoided

    Reducing spray drift by adapting the spraying equipment to the canopy shape in olive orchards with isolated trees

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    The lack of specificity of the spraying equipment commonly used in olive orchards is a remarkable problem, for not allowing farmers to apply adjusted pesticide doses to their trees, making necessary to spray very high liquid volumes that increase the environmental pollution risk. In this context, three prototypes were specially developed to increase the application efficiency in olive orchards with isolated trees, which represent 98% of the olive harvested area in Spain.Postprint (published version
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