25,614 research outputs found
Generalized enthalpy model of a high pressure shift freezing process
High-pressure freezing processes are a novel emerging technology in food processing, offering significant improvements to the quality of frozen foods. To be able to simulate plateau times and thermal history under different conditions, in this work we present a generalized enthalpy model of the high-pressure shift freezing process. The model includes the effects of pressure on conservation of enthalpy and incorporates the freezing point depression of non-dilute food samples. In addition the significant heat transfer effects of convection in the pressurizing medium are accounted for by solving the two-dimensional Navier-Stokes equations. We run the model for several numerical tests where the food sample is agar gel, and find good agreement with experimental data from the literature
Brain-machine interfaces for rehabilitation in stroke: A review
BACKGROUND: Motor paralysis after stroke has devastating consequences for the patients, families and caregivers. Although therapies have improved in the recent years, traditional rehabilitation still fails in patients with severe paralysis. Brain-machine interfaces (BMI) have emerged as a promising tool to guide motor rehabilitation interventions as they can be applied to patients with no residual movement. OBJECTIVE: This paper reviews the efficiency of BMI technologies to facilitate neuroplasticity and motor recovery after stroke. METHODS: We provide an overview of the existing rehabilitation therapies for stroke, the rationale behind the use of BMIs for motor rehabilitation, the current state of the art and the results achieved so far with BMI-based interventions, as well as the future perspectives of neural-machine interfaces. RESULTS: Since the first pilot study by Buch and colleagues in 2008, several controlled clinical studies have been conducted, demonstrating the efficacy of BMIs to facilitate functional recovery in completely paralyzed stroke patients with noninvasive technologies such as the electroencephalogram (EEG). CONCLUSIONS: Despite encouraging results, motor rehabilitation based on BMIs is still in a preliminary stage, and further improvements are required to boost its efficacy. Invasive and hybrid approaches are promising and might set the stage for the next generation of stroke rehabilitation therapies.This study was funded by the Bundesministerium für Bildung und Forschung BMBF MOTORBIC (FKZ13GW0053)andAMORSA(FKZ16SV7754), the Deutsche Forschungsgemeinschaft (DFG), the fortüne-Program of the University of Tübingen (2422-0-0 and 2452-0-0), and the Basque GovernmentScienceProgram(EXOTEK:KK2016/00083). NIL was supported by the Basque Government’s scholarship for predoctoral students
Medium-modified evolution of multiparticle production in jets in heavy-ion collisions
The energy evolution of medium-modified average multiplicities and
multiplicity fluctuations in quark and gluon jets produced in heavy-ion
collisions is investigated from a toy QCD-inspired model. In this model, we use
modified splitting functions accounting for medium-enhanced radiation of gluons
by a fast parton which propagates through the quark gluon plasma. The leading
contribution of the standard production of soft hadrons is found to be enhanced
by the factor while next-to-leading order (NLO) corrections are
suppressed by , where the nuclear parameter accounts for
the induced-soft gluons in the hot medium. The role of next-to-next-to-leading
order corrections (NNLO) is studied and the large amount of medium-induced soft
gluons is found to drastically affect the convergence of the perturbative
series. Our results for such global observables are cross-checked and compared
with their limits in the vacuum and a new method for solving the second
multiplicity correlator evolution equations is proposed.Comment: 21 pages and 8 figures, typo corrections, references adde
Learning to do multiframe wavefront sensing unsupervisedly: applications to blind deconvolution
Observations from ground based telescopes are affected by the presence of the
Earth atmosphere, which severely perturbs them. The use of adaptive optics
techniques has allowed us to partly beat this limitation. However, image
selection or post-facto image reconstruction methods applied to bursts of
short-exposure images are routinely needed to reach the diffraction limit. Deep
learning has been recently proposed as an efficient way to accelerate these
image reconstructions. Currently, these deep neural networks are trained with
supervision, so that either standard deconvolution algorithms need to be
applied a-priori or complex simulations of the solar magneto-convection need to
be carried out to generate the training sets. Our aim here is to propose a
general unsupervised training scheme that allows multiframe blind deconvolution
deep learning systems to be trained simply with observations. The approach can
be applied for the correction of point-like as well as extended objects.
Leveraging the linear image formation theory and a probabilistic approach to
the blind deconvolution problem produces a physically-motivated loss function.
The optimization of this loss function allows an end-to-end training of a
machine learning model composed of three neural networks. As examples, we apply
this procedure to the deconvolution of stellar data from the FastCam instrument
and to solar extended data from the Swedish Solar Telescope. The analysis
demonstrates that the proposed neural model can be successfully trained without
supervision using observations only. It provides estimations of the
instantaneous wavefronts, from which a corrected image can be found using
standard deconvolution technniques. The network model is roughly three orders
of magnitude faster than applying standard deconvolution based on optimization
and shows potential to be used on real-time at the telescope.Comment: 11 pages, 4 figures, accepted for publication in A&
Dynamics of Interacting Scalar Fields in Expanding Space-Time
The effective equation of motion is derived for a scalar field interacting
with other fields in a Friedman-Robertson-Walker background space-time. The
dissipative behavior reflected in this effective evolution equation is studied
both in simplified approximations as well as numerically. The relevance of our
results to inflation are considered both in terms of the evolution of the
inflaton field as well as its fluctuation spectrum. A brief examination also is
made of supersymmetric models that yield dissipative effects during inflation.Comment: 36 pages, 12 figures. Version published in the Physical Review
Caracterização patológica e construtiva de igrejas e capelas do concelho de Estarreja
Este estudo pretende enfatizar a importância de caracterizar construtivamente e
avaliar a preservação de imóveis pertencentes ao património social da Câmara Municipal de
Estarreja, ou seja, a sua herança religiosa e cultural.
São apresentadas 8 fichas criadas especificamente para a inspecção de edifícios religiosos,
procurando-se caracterizar os materiais e os sistemas estruturais e identificar os principais
sintomas patológicos encontrados em igrejas e capelas das sete freguesias do concelho de
Estarreja, bem como sua dimensão e frequência.
Parte deste trabalho consistiu na observação através de registos fotográficos do ambiente
dentro e fora de sete igrejas e dezassete capelas dando-se especial importância ao estado de
conservação de todos os elementos estruturais, realçando-se as paredes estruturais e não
estruturais.
O estado de conservação de cada elemento que compõe este tipo de construção foi
caracterizado com base em observações e na análise dos registos fotográficos. Em cada caso,
tentou-se enquadrar os danos observados numa escala de seis categorias de danos,
correspondendo a ausência de danos a zero e a existência de danos extensos a seis.
O trabalho realizado foi também integrado num CD multimédia interactivo, que reúne
informações detalhadas sobre os edifícios pesquisados e do seu estado de conservação [1]
BEC-BCS crossover in a cold and magnetized two color NJL model
The BEC-BCS crossover for a NJL model with diquark interactions is studied in
the presence of an external magnetic field. Particular attention is paid to
different regularization schemes used in the literature. A thorough comparison
of results is performed for the case of a cold and magnetized two-color NJL
model. According to our results, the critical chemical potential for the BEC
transition exhibits a clear inverse magnetic catalysis effect for magnetic
fields in the range . As for the BEC-BCS
crossover, the corresponding critical chemical potential is very weakly
sensitive to magnetic fields up to , showing a much smaller
inverse magnetic catalysis as compared to the BEC transition, and displays a
strong magnetic catalysis from this point on.Comment: 15 pages, 8 figures; v2 PRD versio
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