911 research outputs found
Asymptotic Behavior of the Einstein-Yang-Mills-Dilaton System for a Closed Friedmann-Lemaitre Universe
We study the coupled Einstein-Yang-Mills-Dilaton (EYMD) equations for a
Fried\-mann-Le\-mai\-tre universe with constant curvature . Our detailed
analysis is restricted to the case where the dilaton potential and the
cosmological constant vanish. Also assuming a static gauge field, we present
analytical and numerical results on the behavior of solutions of the EYMD
equations. For different values of the dilaton coupling constant we analyze the
phase portrait for the time evolution of the dilaton field and give the
behavior of the scale factor. It turns out that there are no inflationary
stages in this model.Comment: 18 pages, Uuencoded gzip compressed tar file containing a latex file
and 12 figures. The epsfig.sty is neede
Mathematical model of feet temperature
In this work it is consider the problem of finding the best approximation to characterize the feet temperature
distribution. For this study it was consider the nonlinear least squares technique, combined with penalty method, to identify
the function that approximate better the data obtained through thermographic images. The preliminary results indicate that the
best function approximation is based on trigonometric sums
Auditory system rehabilitation - available technologies
In this article some of the different technologies and its functioning as well as some technological aids for people with partial or total auditory deficiency will be presented. The objective of the auditory rehabilitation is to develop the capacity of auditory perception to the individual carrying auditory deficiency, with aid of devices that can amplify the sound. Between these devices, we cite: the Baha auditory prostheses, vibrant sound-bridge, the cochlear implantations, the auditory brainstem implants, the hearing prosthesis, the bone conduction prostheses and the intra-channels hearing. Some technological aiding devices not used in the ear are also presented such as the signal amplifier to phone, amplifier magnetic field to TV, sign language translator, phone with handset and light bell for home
Halo Properties in Cosmological Simulations of Self-Interacting Cold Dark Matter
We present a comparison of halo properties in cosmological simulations of
collisionless cold dark matter (CDM) and self-interacting dark matter (SIDM)
for a range of dark matter cross sections. We find, in agreement with various
authors, that CDM yields cuspy halos that are too centrally concentrated as
compared to observations. Conversely, SIDM simulations using a Monte Carlo
N-body technique produce halos with significantly reduced central densities and
flatter cores with increasing cross section. We introduce a concentration
parameter based on enclosed mass that we expect will be straightforward to
determine observationally, unlike that of Navarro, Frenk & White, and provide
predictions for SIDM and CDM. SIDM also produces more spherical halos than CDM,
providing possibly the strongest observational test of SIDM. We discuss our
findings in relation to various relevant observations as well as SIDM
simulations of other groups. Taking proper account of simulation limitations,
we find that a dark matter cross section per unit mass of sigma_DM ~=
10^{-23}-10^{-24} cm^2/GeV is consistent with all current observational
constraints.Comment: 14 pages, submitted to Ap
Cell-free layer (CFL) analysis in a glass capillary: comparison between a manual and automatic method
In this study, in vitro blood flowing through a 100 m glass capillary was studied. The images were captured
using a confocal system and post-processed using Image J and MatLab. The aim of the present work, was to measure the
trajectories of the cell-free layer (CFL) by using two different methods, i. e., a manual method (MM) and an automatic method (AM). For theMM we have used amanual tracking plugin (MTrackJ) from Image J to track labeled red blood cells (RBCs) flowing around the boundary of the RBCs core. For the AM we have used a MatLab scripts to measure automatically the CFL trajectories. The preliminary numerical results suggest that the CFL trajectories follow a
polynomial function for both methods.The authors acknowledge the financial support provided by: PTDC/SAU-BEB/108728/2008, PTDC/SAU-BEB/105650/2008, PTDC/EME-MFE/099109/2008 and PTDC/SAU-ENB/116929/2010 from the FCT (Science and Technology Foundation) and COMPETE, Portugal
Monitoring feet temperature using thermography
Studies show that regular monitoring of feet temperature may limit the incidence of disabling conditions such as foot ulcers and lower-limb amputations. Infrared thermometry and liquid crystal thermography were identified as the leading technologies in use today. In this study, we analysed the maximum temperature and tested some mathematical models for the foot temperature distribution
Monitorização de pragas associadas à amendoeira em Alfândega-da-Fé (Trás-os-Montes)
Trás-os-Montes é uma das principais regiões produtoras de amêndoa em Portugal. Esta
cultura apresenta problemas fitossanitários associados a pragas que podem originar
estragos significativos na produção da planta. A monitorização dessas pragas constitui
um aspeto importante com vista a uma correta tomada de decisão no que diz respeito
ao combate a efetuar contra cada espécie. O objetivo deste trabalho foi monitorizar as
populações das principais pragas da amendoeira, nomeadamente Tetranychus urticae
koch, Monosteira unicostata (Mulsant & Rey, 1852), Anarsia lineatella Zeller, Grapholita
molesta (Busck), Cossus cossus L. e Zeuzera pyrina L. na zona de Alfândega-da-Fé, em
Trás-os-Montes. Para a monitorização das populações de aranhiço-amarelo T. urticae e
de M. unicostata realizaram-se observações entre meados de julho e meados de agosto
de 2015 em um amendoal não regado através da colheita de 20 folhas em 20 árvores
em cada uma das variedades "Giorieta" e "Masbovera" e, no laboratório, contaram-se
ovos, ninfas e adultos de T. urticae e adultos de M. unicostata. Para a monitorização de
A. lineatella, G. molesta, C. cossus e Z. pyrina instalaram-se, em dois amendoais (um
regado e outro não regado), três armadilhas delta com feromona para captura das duas
primeiras espécies e três armadilhas tipo funil com feromona para captura das duas
segundas. Estas armadilhas permaneceram instaladas desde inícios de maio até finais
de novembro de 2015. Não se verificaram diferenças significativas entre as populações
de T. urticae e de M. unicostata capturadas nas duas variedades de amendoeira, nem
entre as populações das restantes pragas capturadas nos dois amendoais. As populações
de T. urticae registaram um pico de abundância em meados de julho e foi atingido o seu
nível económico de ataque. As populações de A. lineatel/o e de G. molesta atingiram
níveis populacionais relativamente elevados (com um pico médio de capturas de 74
e 9 indivíduos, respetivamente), mas apenas 1 indivíduo de C. cossus e 1 de Z. pyrina
foram capturados. Estes resultados permitiram conhecer os níveis populacionais das
pragas associadas à amendoeira e fazer recomendações, aos parceiro do projeto, sobre
a melhor ocasião para efetuar o tratamento fitossanitário.Este trabalho foi realizado no âmbito do projeto PRODER 54610
- Estratégias integradas para o aumento da produtividade da amendoeira em Trás-osMontes,
financiado pelo Programa de Desenvolvimento Rural (PRODER) no âmbito da
medida 4.1 - Cooperação para a Inovação (Apoio à Inovação na Agricultura, Agroindústria
e Floresta).info:eu-repo/semantics/publishedVersio
Blood flow in a bifurcation and confluence microchannel: effect of the cell-free layer in velocity profiles
A few detailed studies have been performed in complex in vitro microvascular networks composed by bifurcations and confluences. The main purpose of the present work is to numerically simulate the flow of two distinct fluids through bifurcation and confluence geometries, i. e red blood cells (RBCs)suspended in Dextran40 with about 14% of heamatocrit and pure water. The simulations of pure water and RBCs flows were performed resorting to the
commercial finite volume software package FLUENT.
A well known hemodynamic phenomenon, known as Fahraeus-Lindqvist effect, observed in both in vivo and in vitro studies, results in the formation of a marginal cell-free layer (CFL) at regions adjacent to the wall. Recently, studies have shown that the formation of the CFL is affected by the
geometry of the microchannel and for the case of the confluences a CFL tend to appear in the middle of the microchannel after the apex of the confluence. By using the CFL experimental data, the main objective of this work is to implement a CFL in the numerical simulations in order to obtain a better understanding of the effect of this layer on the velocity profiles
Visualization and measurement of red blood cells flowing in microfluidic devices
Several experimental techniques were performed in the past years using in vitro environments, in an attempt to not only understand the blood flow behaviour in microcirculation but also develop microfluidic devices as an alternative clinical methodology to detect blood diseases. Hence, the visualization and measurement of red blood cells (RBCs) flowing in a microfluidic device are important to provide not only essential information about hydrodynamic characteristics of the blood but also vital information to diagnose the initial symptoms of diseases during clinical investigations. For instance, RBC rigidity has been correlated with myocardial infarction, diabetes mellitus, hypertension, and also other haematological disorders and diseases
that affect RBC deformation more directly, such as, hereditary spherocytosis, sickle cell anaemia and malaria. Regarding a better understanding of the RBCs deformation and motion, we present in this paper a compilation of studies made in our research group, using several microfluidic devices with different microchannel geometries and fabrication techniques (i.e., soft-lithography, xurography and hybrids) that focus in the shear and extensional flow
behaviour, either in healthy or chemically stiffed RBCs.The authors acknowledge the financial support provided by 2007 Global COE Program “Global Nano-Biomedical Engineering Education and Research
Network”, Japan and grant-in-Aid for Science and Technology, PTDC/SAU-BEB/105650/2008, PTDC/EME-MFE/099109/2008, PTDC/SAUENB/116929/2010, EXPL/EMS-SIS/2215/2013, scholarship SFRH/BD/91192/2012 and scholarship SFRH/BD/89077/2012 from FCT (Science and
Technology Foundation), COMPETE, QREN and European Union (FEDER). The authors are also very grateful to Dr. Mónica Oliveira (Strathclyde
University), Professor Takuji Ishikawa and Professor Takami Yamaguchi (Tohoku University) for their suggestions and support to this research work
No Conclusive Evidence for Transits of Proxima b in MOST photometry
The analysis of Proxima Centauri's radial velocities recently led
Anglada-Escud\'e et al. (2016) to claim the presence of a low mass planet
orbiting the Sun's nearest star once every 11.2 days. Although the a-priori
probability that Proxima b transits its parent star is just 1.5%, the potential
impact of such a discovery would be considerable. Independent of recent radial
velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31
days in 2015 with the MOST space telescope. We report here that we cannot make
a compelling case that Proxima b transits in our precise photometric time
series. Imposing an informative prior on the period and phase, we do detect a
candidate signal with the expected depth. However, perturbing the phase prior
across 100 evenly spaced intervals reveals one strong false-positive and one
weaker instance. We estimate a false-positive rate of at least a few percent
and a much higher false-negative rate of 20-40%, likely caused by the very high
flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth
ground-based photometry reveals that the signal is somewhat, but not
conclusively, disfavored (1-2 sigmas) leading us to argue that the signal is
most likely spurious. We expect that infrared photometric follow-up could more
conclusively test the existence of this candidate signal, owing to the
suppression of flare activity and the impressive infrared brightness of the
parent star.Comment: Accepted to ApJ. Posterior samples, MOST photometry and HATSouth
photometry are all available at https://github.com/CoolWorlds/Proxim
- …
