4,362 research outputs found
Magnetic Properties of FeCo Films Prepared by Co-Sputtering and Hydrogenous Gas Reactive Sputtering
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Modeling and simulation of phase-transitions in multicomponent aluminum alloy casting
The casting process of aluminum products involves the spatial distribution of alloying elements. It is essential that these elements are uniformly distributed in order to guarantee reliable and consistent products. This requires a good understanding of the main physical mechanisms that affect the solidification, in particular the thermodynamic description and its coupling to the transport processes of heat and mass that take place. The continuum modeling is reviewed and methods for handling the thermodynamics component of multi-element alloys are proposed. Savings in data-storage and computing costs on the order of 100 or more appear possible, when a combination of data-reduction and data-representation methods is used. To test the new approach a simplified model was proposed and shown to qualitatively capture the evolving solidification front
Dentate granule cells form novel basal dendrites in a rat model of temporal lobe epilepsy.
Mossy fibre sprouting and re-organization in the inner molecular layer of the dentate gyrus is a characteristic of many models of temporal lobe epilepsy including that induced by perforant-path stimulation. However, neuroplastic changes on the dendrites of granule cells have been less-well studied. Basal dendrites are a transient morphological feature of rodent granule cells during development. The goal of the present study was to examine whether granule cell basal dendrites are generated in rats with epilepsy induced by perforant-path stimulation. Adult Wistar rats were stimulated for 24 h at 2 Hz and with intermittent (1/min) trains (10 s duration) of single stimuli at 20 Hz (20 V, 0.1 ms) delivered 1/min via an electrode placed in the angular bundle. The brains of these experimental rats and age- and litter-matched control animals were processed for the rapid Golgi method. All rats with perforant-path stimulation displayed basal dendrites on many Golgi-impregnated granule cells. These basal dendrites mainly originated from their somata at the hilar side and then extended into the hilus. Quantitative analysis of more than 800 granule cells in the experimental and matched control brains showed that 6-15% (mean=8.7%) of the impregnated granule cells have spiny basal dendrites on the stimulated side, as well as the contralateral side (mean=3.1%, range=2.9-3.9%) of experimental rats, whereas no basal dendrites were observed in the dentate gyrus from control animals. The formation of basal dendrites appears to be an adaptive morphological change for granule cells in addition to the previously described mossy fibre sprouting, as well as dendritic and somatic spine formation observed in the dentate gyrus of animal and human epileptic brains. The presence of these dendrites in the subgranular region of the hilus suggests that they may be postsynaptic targets of the mossy fibre collaterals
A GPU-based survey for millisecond radio transients using ARTEMIS
Astrophysical radio transients are excellent probes of extreme physical
processes originating from compact sources within our Galaxy and beyond. Radio
frequency signals emitted from these objects provide a means to study the
intervening medium through which they travel. Next generation radio telescopes
are designed to explore the vast unexplored parameter space of high time
resolution astronomy, but require High Performance Computing (HPC) solutions to
process the enormous volumes of data that are produced by these telescopes. We
have developed a combined software /hardware solution (code named ARTEMIS) for
real-time searches for millisecond radio transients, which uses GPU technology
to remove interstellar dispersion and detect millisecond radio bursts from
astronomical sources in real-time. Here we present an introduction to ARTEMIS.
We give a brief overview of the software pipeline, then focus specifically on
the intricacies of performing incoherent de-dispersion. We present results from
two brute-force algorithms. The first is a GPU based algorithm, designed to
exploit the L1 cache of the NVIDIA Fermi GPU. Our second algorithm is CPU based
and exploits the new AVX units in Intel Sandy Bridge CPUs.Comment: 4 pages, 7 figures. To appear in the proceedings of ADASS XXI, ed.
P.Ballester and D.Egret, ASP Conf. Se
Reply to Comment by Velasco on âHigh-Resolution, Multilayer Modeling of Singaporeâs Urban Climate Incorporating Local Climate Zonesâ
In response to the comment on our paper âHighâresolution, multilayer modeling of Singapore's urban climate incorporating local climate zones,â we provide detailed response to each of the incorrect accusations with scientifically based evidence. We have evaluated our model using all the available observational data, and the results showed good agreement. Our modeling study includes assumptions, as all modeling work does, and we have discussed their rationales and possible implications
BPR Implementation: A Decision-Making Strategy
To support the efficient appraisal and selection of available best practices, this paper proposes a strategy for the implementation of Business Process Redesign (BPR). Its backbone is formed by the analytical hierarchy process (AHP) multi-criteria method and our earlier research on the popularity and impact of redesign best practices. Using (AHP) we derive a classification of most suitable best practices for the process being redesigned. Criteria such as the popularity, the impact, the goals and the risks of BPR implementation are taken into account. A case study of a municipality in the Netherlands is included. It discusses which best practices should be applied to redesign the invoicing process at the municipality. © Springer-Verlag Berlin Heidelberg 2006
Some studies on the deformation of the membrane in an RF MEMS switch
Radio Frequency (RF) switches of Micro Electro Mechanical Systems (MEMS) are appealing to the mobile industry because of their energy efficiency and ability to accommodate more frequency bands. However, the electromechanical coupling of the electrical circuit to the mechanical components in RF MEMS switches is not fully understood.
In this paper, we consider the problem of mechanical deformation of electrodes in RF MEMS switch due to the electrostatic forces caused by the difference in voltage between the electrodes. It is known from previous studies of this problem, that the solution exhibits multiple deformation states for a given electrostatic force. Subsequently, the capacity of the switch that depends on the deformation of electrodes displays a hysteresis behaviour against the voltage in the switch.
We investigate the present problem along two lines of attack.
First, we solve for the deformation states of electrodes using numerical methods such as finite difference and shooting methods. Subsequently, a relationship between capacity and voltage of the RF MEMS switch is constructed. The solutions obtained are exemplified using the continuation and bifurcation package AUTO.
Second, we focus on the analytical methods for a simplified version of the problem and on the stability analysis for the solutions of deformation states. The stability analysis shows that there exists a continuous path of equilibrium deformation states between the open and closed state
AvaluaciĂł de la capacitat de salt i estat ponderal dâestudiants de dansa clĂ ssica de lâescola del Teatro ColĂłn de Buenos Aires
 IntroducciĂł: Lâobjectiu dâaquest estudi fou avaluar la capacitat de salt, el pes corporal i la talla dâestudiants de lâescola de dansa clĂ ssica del Teatro ColĂłn de Buenos Aires.Material i mĂštodes: Cinquanta estudiants femenines (10 a 21 anys) i 16 masculins (10 a 26 anys). Variables: estatura (m), pes (kg), Ăndex de massa corporal, alçada (cm) del salt sense contramoviment (SJ), del salt amb contramoviment (CMJ), Ăndex dâelasticitat (IE) (%).Resultats: Pes baix el 38% de les dones i el 6,3% dels homes. A les dones seâls aplicĂ el test t per a grups independents segons categories dâedat, entre categories dâestat nutricional, per als salts SJ, CMJ, IE, sense diferĂšncies significatives. Es realitzĂ un ANOVA dâuna via entre categories dâedat per a lâSJ, CMJ, IE, sense diferĂšncies significatives per a lâSJ (F = 0,8; p = 0,46), CMJ (F = 0,28; p = 0,76), IE (F = 0,61; p = 0,55). En els homes la prova ANOVA dâuna via entre categories dâedat mostrĂ significaciĂł en lâSJ (F = 9,97; p = 0,002) i el CMJ (F = 17,58; p = 0,00). Hi haguĂ© diferĂšncies entre la categoria 1 amb la 2 i la 3, que tendiren a agrupar-se (test post hoc de ScheffĂ©, p < 0,05). IE: test de Kruskal-Wallis, sense diferĂšncies significatives entre categories dâedat (Ï2 = 2,17; p = 0,34). Qualitat del salt: 68% dels homes i 42% de les dones assoliren un IE â„ 6%, cosa que indica bona relaciĂł CMJ/SJ.Conclusions: Es suggereixen controls de salut atĂšs lâelevat nombre de ballarines de baix pes. Pel que fa al salt, el grup de dones en podria millorar la capacitat
Seizure-induced basal dendrites on granule cells
Seizure-induced hilar basal dendrites on dentate granule cells are observed in several rodent models of temporal lobe epilepsy. Ultrastructural evidence showed that basal dendrites receive predominantly excitatory synapses, including many from mossy fibers. Such highly interconnected granule cells with basal dendrites are suggested to enhance hyperexcitability within the dentate network. For an expanded treatment of this topic see Jasper's Basic Mechanisms of the Epilepsies, Fourth Edition (Noebels JL, Avoli M, Rogawski MA, Olsen RW, Delgado-Escueta AV, eds) published by Oxford University Press (available on the National Library of Medicine Bookshelf [NCBI] at). © 2010 International League Against Epilepsy
Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating
Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification was produced by heating the ground of the street canyon. Using the Boussinesq approximation, thermal buoyancy forces were taken into account in both the NavierâStokes equations and the transport equation for subgrid-scale turbulent kinetic energy (TKE). The LESs were validated against experimental data obtained in wind-tunnel studies before the model was applied to study the detailed turbulence, temperature, and pollutant dispersion characteristics in the street canyon of aspect ratio 1. The effects of different Richardson numbers (Ri) were investigated. The ground heating significantly enhanced mean flow, turbulence, and pollutant flux inside the street canyon, but weakened the shear at the roof level. The mean flow was observed to be no longer isolated from the free stream and fresh air could be entrained into the street canyon at the roof-level leeward corner. Weighed against higher temperature, the ground heating facilitated pollutant removal from the street canyon.Singapore-MIT Alliance for Research and Technology. Center for Environmental Sensing and Monitorin
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