564 research outputs found
Port-Access cardiac surgery: from a learning process to the standard.
Background: Port-Access™ surgery has been one of the
most innovative and controversial methods in the spectrum
of minimally invasive techniques for cardiac operations and
has been widely used for the treatment of several cardiac diseases.
The technique was introduced in our center to evaluate
its efficacy in reproducing standardized results without an
additional risk.
Methods: Endovascular cardiopulmonary bypass (CPB)
through femoral access and endoluminal aortic occlusion
were used in 129 patients for a variety of surgical procedures,
all of which were video-assisted. A minimal (4-6 cm) anterior
thoracotomy through the fourth intercostal space was used in
all cases as the surgical approach.
Results: More than 96% of the planned cases concluded
as true Port-Access™ procedures. Mean CBP and crossclamp
times were 87.2 min. ± 51.2 (range of 10-457) and
54.9 min. ± 30.6 (range of 10-190), respectively. Hospital
mortality for the overall group was 1.5%, and mitral valve
surgery had a 2.2% hospital death rate. The incidence of early
neurological events was 0.7%. Mean extubation time, ICU
stay, and total length of hospital stay were 5 hours ± 6 hrs.
(range of 2-32), 12 hours ± 11.8 hrs. (range of 5-78), and
7 days ± 7.03 days (range of 1-72), respectively.
Conclusions: Our experience indicates that the Port-
Access™ technique is safe and permits reproduction of standardized
results with the use of a very limited surgical
approach. We are convinced that this is a superior procedure
for certain types of surgery, including isolated primary or
redo mitral surgery, repair of a variety of atrial septal defects
(ASDs), and atrial tumors. It is especially useful in high-risk
patients, such as elderly patients or those requiring reoperation.
Simplification of the procedure is nevertheless desirable
in order to further reduce the time of operation and to
address other drawbacks
Uncertainty Model For Quantitative Precipitation Estimation Using Weather Radars
This paper introduces an uncertainty model for
the quantitatively estimate precipitation using weather radars.
The model considers various key aspects associated to radar
calibration, attenuation, and the tradeoff between accuracy
and radar coverage. An S-band-radar case study is presented to
illustrate particular fractional-uncertainty calculations obtained
to adjust various typical radar-calibration elements such as
antenna, transmitter, receiver, and some other general elements
included in the radar equation. This paper is based in “Guide to
the expression of Uncertainty in measurement” [1] and the results
show that the fractional uncertainty calculated by the model was
40 % for the reflectivity and 30% for the precipitation using the
Marshall Palmer Z-R relationship
Information flow and optimization in transcriptional control
In the simplest view of transcriptional regulation, the expression of a gene
is turned on or off by changes in the concentration of a transcription factor
(TF). We use recent data on noise levels in gene expression to show that it
should be possible to transmit much more than just one regulatory bit.
Realizing this optimal information capacity would require that the dynamic
range of TF concentrations used by the cell, the input/output relation of the
regulatory module, and the noise levels of binding and transcription satisfy
certain matching relations. This parameter-free prediction is in good agreement
with recent experiments on the Bicoid/Hunchback system in the early Drosophila
embryo, and this system achieves ~90% of its theoretical maximum information
transmission.Comment: 5 pages, 4 figure
Género, rendimento escolar e as atitudes dos alunos e alunas face às disciplinas de matemática e língua portuguesa
A investigação revela que o rendimento escolar nas várias disciplinas só consegue ser
explicado com recurso a análises multidimensionais que conjugam fatores pessoais,
socioculturais e escolares. Não desconsiderando o facto de as variáveis de âmbito cognitivo se
revelarem preditoras da variabilidade no rendimento escolar, este só poderá ser efetivamente
compreendido com o recurso complementar e integrado de outras variáveis, como as
desenvolvimentais, as atitudinais e socioculturais. As questões de género que emergem do
domínio sociocultural intersectam os outros domínios e influenciam, nomeadamente, as
atitudes que os alunos e as alunas desenvolvem face às disciplinas escolares e,
consequentemente, os respetivos resultados escolares.
Este estudo enquadra-se no âmbito de um projeto de investigação intitulado “RED- Rendimento
Escolar e Desenvolvimento: um estudo longitudinal sobre os efeitos das transições em alunos
Portugueses” que está a ser desenvolvido em várias escolas portugueses abrangendo 1400
alunos. Apoiando-nos numa abordagem sensível ao género, nesta comunicação iremos,
especificamente, discutir os efeitos que as atitudes dos alunos e das alunas face às disciplinas
de matemática, português e ciências (ciências da natureza, ciências físico-químicas e físicoquímica)
têm no respetivo rendimento escolar utilizando os resultados da aplicação de 3
questionários de atitudes (QAFM, QAFP, QAFCdN, QAFCN, QAFCFQ) e as classificações
escolares obtidas pelos alunos e alunas
Effective nonlinear Ehrenfest hybrid quantum-classical dynamics
The definition of a consistent evolution equation for statistical hybrid
quantum-classical systems is still an open problem. In this paper we analyze
the case of Ehrenfest dynamics on systems defined by a probability density and
identify the relations of the non-linearity of the dynamics with the
obstructions to define a consistent dynamics for the first quantum moment of
the distribution. This first quantum moment represents the physical states as a
family of classically-parametrized density matrices , for
a classical point; and it is the most common representation of hybrid systems
in the literature. Due to this obstruction, we consider higher order quantum
moments, and argue that only a finite number of them are physically measurable.
Because of this, we propose an effective solution for the hybrid dynamics
problem based on approximating the distribution by those moments and
representing the states by them.Comment: 21 pages. Minor correction in the list of affiliation
New insights into Capsicum spp relatedness and the diversification process of Capsicum annuum in Spain
The successful exploitation of germplasm banks, harbouring plant genetic resources indispensable for plant breeding, will depend on our ability to characterize their genetic diversity. The Vegetable Germplasm Bank of Zaragoza (BGHZ) (Spain) holds an important Capsicum annuum collection, where most of the Spanish pepper variability is represented, as well as several accessions of other domesticated and non-domesticated Capsicum spp from all over the five continents. In the present work, a total of 51 C. annuum landraces (mainly from Spain) and 51 accessions from nine Capsicum species maintained at the BGHZ were evaluated using 39 microsatellite (SSR) markers spanning the whole genome. The 39 polymorphic markers allowed the detection of 381 alleles, with an average of 9.8 alleles per locus. A sizeable proportion of alleles (41.2%) were recorded as specific alleles and the majority of these were present at very low frequencies (rare alleles). Multivariate and model-based analyses partitioned the collection in seven clusters comprising the ten different Capsicum spp analysed: C. annuum, C. chinense, C. frutescens, C. pubescens, C. bacatum, C. chacoense and C. eximium. The data clearly showed the close relationships between C. chinense and C. frutescens. C. cardenasii and C. eximium were indistinguishable as a single, morphologically variable species. Moreover, C. chacoense was placed between C. baccatum and C. pubescens complexes. The C. annuum group was structured into three main clusters, mostly according to the pepper fruit shape, size and potential pungency. Results suggest that the diversification of C. annuum in Spain may occur from a rather limited gene pool, still represented by few landraces with ancestral traits. This ancient population would suffer from local selection at the distinct geographical regions of Spain, giving way to pungent and elongated fruited peppers in the South and Center, while sweet blocky and triangular types in Northern Spain
Correction: Absence of Zika virus among pregnant women in Vietnam in 2008.
International audienc
OUT to IN: Efeitos de um programa de intervenção psicomotora na autorregulação de crianças em idade pré-escolar
A autorregulação na idade pré-escolar é preditora do bem-estar e do sucesso pessoal e social na vida
adulta. O programa OUT to IN propõe uma abordagem de mediação corporal implementada no
espaço exterior do jardim de infância com o objetivo de melhorar as competências sócio-emocionais.
Este estudo tem como objetivo examinar o impacto do OUT to IN, na autorregulação de crianças em
idade pré-escolar. Participaram no estudo 32 crianças com idades entre os 3 e os 5 anos, 15 alocadas
ao Grupo de Controlo, que não participou na intervenção e 17 ao Grupo Experimental (GE), que
participou durante 10 semanas em sessões bissemanais, envolvendo atividades semi-dirigidas de
jogo de exercício, relaxação e simbolização. A autorregulação das crianças foi avaliada através de
duas provas, antes e após a intervenção. No final do programa, o GE evidenciou uma melhoria
significativa da autorregulação, avaliada por ambas as provas, comparativamente ao grupo de
controlo. Os resultados sugerem que o OUT to IN contribui para o desenvolvimento da
autorregulação de crianças de idade pré-escolar
Critical Dynamics of a Vortex Loop Model for the Superconducting Transition
We calculate analytically the dynamic critical exponent measured in
Monte Carlo simulations for a vortex loop model of the superconducting
transition, and account for the simulation results. In the weak screening
limit, where magnetic fluctuations are neglected, the dynamic exponent is found
to be . In the perfect screening limit, . We relate
to the actual value of observable in experiments and find that , consistent with some experimental results
Temperature and magnetic-field dependence of the conductivity of YBaCuO films in the vicinity of superconducting transition: Effect of Tc-inhomogeneity
Temperature and magnetic field dependences of the conductivity of YBaCuO
films in the transition region are analyzed taking into account spatial
inhomogeneity in transition temperature, Tc.
(i) An expression for the superconducting contribution to conductivity,
\sigma_s(T,H,Tc), of a homogeneous superconductor for H<<Hc2(T=0) is obtained
using the solution of the Ginzburg-Landau equation in form of perturbation
expansions [S.Ullah, A.T.Dorsey, PRB 44, 262 (1991)].
(ii) The error in \sigma_s(T,H,Tc) occurring due to the presence of
Tc-inhomogeneity is calculated and plotted on an H-T plane diagram. These
calculations use an effective medium approximation and a Gaussian distribution
of Tc.
(iii) Measuring the temperature dependences of a voltage, induced by a
focused electron beam, we determine spatial distributions of the critical
temperature for YBaCuO microbridges with a 2 micron resolution. A typical
Tc-distribution dispersion is found to be approximately 1K. For such
dispersion, error in \sigma_s(T,H,Tc) due to Tc-inhomogeneity exceeds 30% for
magnetic fields H < 1 T and temperatures |T-Tc| < 0.5 K.
(iv) Experimental R(T,H) dependences of resistance are well described by a
numerical solution of a set of Kirchoff equations for the resistor network
based on the measured spatial distributions of Tc and the expression for
\sigma_s(T,H,Tc).Comment: REVTeX, 12 pages including 7 figures, resubmitted to Phys. Rev.
- …