906 research outputs found
Spectral response of atmospheric electric field measurements near AC high voltage power lines
A sua necessidade e importùncia na prevenção da criminalidade
A necessidade de que haja um Sistema de Investigação Criminal (SIC) coeso na PolĂcia Nacional de SĂŁo TomĂ© e PrĂncipe (PNSTP) Ă© o culminar de uma resposta mais acertada/eficaz, capaz de fazer frente a estas transformaçÔes (a globalização e a alteração do mundo criminolĂłgico, isto Ă©, os seus modus operandi) que se tem presenciado atualmente, nĂŁo sĂł ao nĂvel internacional como tambĂ©m ao nĂvel nacional. Neste contexto Ă© essencial a implementação de uma polĂtica eficaz para que a PNSTP adquira, de facto, verdadeiras competĂȘncias e capacidades de investigação. No Ăąmbito deste estudo pretende-se identificar, se o modelo de investigação criminal existente em Portugal Ă© adequado para a realidade santomense e desenvolver um modelo para SĂŁo TomĂ© e PrĂncipe. O estudo realizado revela que hĂĄ necessidade de implementação de um modelo de investigação criminal em STP, que assente numa polĂtica de partilha de competĂȘncia de investigação criminal com a PolĂcia de Investigação Criminal (PIC), sem prejuĂzo Ă investigação de crimes reservados a esta Ășltima. Conclui-se que o modelo existente em Portugal serve para ser implementado em STP.The need for the existence of a strong Criminal Investigation System in SĂŁo TomĂ© and Principeâs National Police is the summit of a more assertive/effective response, capable of facing this transformations (globalization and the modification of the criminal world, this is, itâs modi operandi) that are seen nowadays, not only in an international level but also in the national level. In this context it is of substance the implementation of a effective policy so that STPNP acquires, in fact, real competences and capabilities for criminal investigation. In this study we aim to identify, if the criminal investigation model which exists in Portugal is adequate for the SĂŁo TomĂ© and Principeâs reality and to develop a model for SĂŁo TomĂ© and Principe and, consequently, for the STPNP through the creation of a Criminal Investigation System. The study reveals that there is the need to implement a criminal investigation model in STP which stands on a policy of shared criminal investigation competences with the Criminal Investigation Police, without prejudice regarding the investigation which are reserved to the latter. It is concluded that the model which exists in Portugal is suitable for implementation in STP
Compactness and asymptotic behavior in nonautonomous linear parabolic equations with unbounded coefficients in
We consider a class of second order linear nonautonomous parabolic equations
in R^d with time periodic unbounded coefficients. We give sufficient conditions
for the evolution operator G(t,s) be compact in C_b(R^d) for t>s, and describe
the asymptotic behavior of G(t,s)f as t-s goes to infinity in terms of a family
of measures mu_s, s in R, solution of the associated Fokker-Planck equation
Modulation of urban atmospheric electric field measurements with the wind direction in Lisbon (Portugal)
Atmospheric electric field measurements (potential gradient, PG) were retrieved in
the urban environment of the city of Lisbon (Portugal). The measurements were performed
with a Benndorf electrograph at the Portela Meteorological station in the suburbs of the city
(NE from the centre). The period of 1980 to 1990 is considered here. According to wind
direction, different content and types of ions and aerosols arrive at the measurement site
causing significant variations to the PG. To the south there are significant pollution sources
while to the north such sources are scarcer . The Iberian Peninsula is found east of the station
and the Atlantic Ocean covers the western sector, Wind directions are divided in four sectors:
i) NW: 270Âș †Ξ †360Âș; ii) NE: 0 †Ξ †90Âș; iii) SE: 90 †Ξ †180Âș; iv) SW: 180Âș †Ξ †270Âș.
Analysis of weekly cycle, caused by anthropogenic pollution related with urban activity, was
undertaken for each wind sector. NW sector has been shown to be less affected by this cycle,
which is attributed to the effect of marine air. The daily variation of NE sector for weekends
reveals a similar behaviour to the Carnegie curve, which corresponds to a clean air daily variation of PG, following universal time, independent of measurement site
New insight into the relation between star formation activity and dust content in galaxies
(Abridged) We assemble a sample of 3258 low-redshift galaxies from the SDSS
DR6 with complementary photometric observations by GALEX, 2MASS and IRAS at
far-ultraviolet and infrared wavelengths. We use a recent, simple but
physically motivated model to interpret the observed spectral energy
distributions of the galaxies in this sample in terms of statistical
constraints on physical parameters describing the star formation history and
dust content. The focus on a subsample of 1658 galaxies with highest S/N
observations enables us to investigate most clearly several strong correlations
between various derived physical properties of galaxies. We find that the
typical dust mass of a star-forming correlates remarkably well with the star
formation rate (SFR). We also find that the dust-to-stellar mass ratio, the
ratio of dust mass to star formation rate and the fraction of dust luminosity
contributed by the diffuse interstellar medium all correlate strongly with
specific SFR. A comparison with recent models of chemical and dust evolution of
galaxies suggests that these correlations could arise, at least in part, from
an evolutionary sequence. As galaxies form stars, their ISM becomes enriched in
dust, while the drop in gas supply makes the specific SFR decrease.
Interestingly, as a result, a young, actively star-forming galaxy with low
dust-to-gas ratio may still be highly dusty because it contains large amounts
of interstellar gas. This may be important for the interpretation of the
infrared emission from young, gas-rich star-forming galaxies at high redshift.
Our study provides a useful local reference for future statistical studies of
the star formation and dust properties of galaxies at high redshifts.Comment: 15 pages, 10 figures, accepted for publication in MNRAS.
Full-resolution figures available from
http://users.physics.uoc.gr/~dacunha/paper_dacunha.pd
Dispersion and collapse in stochastic velocity fields on a cylinder
The dynamics of fluid particles on cylindrical manifolds is investigated. The
velocity field is obtained by generalizing the isotropic Kraichnan ensemble,
and is therefore Gaussian and decorrelated in time. The degree of
compressibility is such that when the radius of the cylinder tends to infinity
the fluid particles separate in an explosive way. Nevertheless, when the radius
is finite the transition probability of the two-particle separation converges
to an invariant measure. This behavior is due to the large-scale
compressibility generated by the compactification of one dimension of the
space
Homogenized dynamics of stochastic partial differential equations with dynamical boundary conditions
A microscopic heterogeneous system under random influence is considered. The
randomness enters the system at physical boundary of small scale obstacles as
well as at the interior of the physical medium. This system is modeled by a
stochastic partial differential equation defined on a domain perforated with
small holes (obstacles or heterogeneities), together with random dynamical
boundary conditions on the boundaries of these small holes.
A homogenized macroscopic model for this microscopic heterogeneous stochastic
system is derived. This homogenized effective model is a new stochastic partial
differential equation defined on a unified domain without small holes, with
static boundary condition only. In fact, the random dynamical boundary
conditions are homogenized out, but the impact of random forces on the small
holes' boundaries is quantified as an extra stochastic term in the homogenized
stochastic partial differential equation. Moreover, the validity of the
homogenized model is justified by showing that the solutions of the microscopic
model converge to those of the effective macroscopic model in probability
distribution, as the size of small holes diminishes to zero.Comment: Communications in Mathematical Physics, to appear, 200
Group-based physical activity interventions for postpartum women with children aged 0â5Â years old: a systematic review of randomized controlled trials
Background: It is estimated that less than one third of women (28%) worldwide, are not sufficiently active, and there is evidence indicating physical activity (PA) participation is lower during pregnancy and the postpartum period. Despite the importance of educating and encouraging postpartum women to engage in PA, existing systematic reviews have only focused on examining the impact of individually tailored PA interventions and on specific postpartum populations such as women who are inactive (i.e., do not meet PA recommendations) or women at risk of gestational diabetes mellitus or postnatal depression. This review aims to fill this gap by examining the impact of group-based PA interventions on postpartum womenâs PA levels or other health behavior outcomes. Methods: A systematic literature search was conducted using four electronic databases (MEDLINE, CINAHL, EMBASE and PsychInfo) of published studies between 1st January 2000 and 31st October 2020. Studies were included if they targeted postpartum women with no current health conditions, had children aged 0â5Â years, and engaged postpartum women in a group-based PA program that reported PA or other health behavior outcomes. Out of a total of 1091 articles that were initially identified, six were included. Results: Group-based PA interventions were moderately successful in changing or increasing postpartum womenâs self-reported PA levels and psychological wellbeing in the first 2Â years of their offspringâs life. Overall, group-based PA interventions were not successful in changing or increasing postpartum womenâs objectively measured PA levels, but only one study objectively measured postpartum womenâs PA levels. Narrative synthesis highlights the heterogeneity of the outcomes and methodologies used, and the low to medium risk of bias in the included studies. Conclusion: To strengthen the evidence-base for group-based PA programs with postpartum women there is an on-going need for more rigorous randomised controlled trials of appropriate length (at least 3Â months in duration) with an adequate dose of group-based PA sessions per week (to meet PA guidelines), and that utilise objective measures of PA. In addition, future PA interventions for this population should include, at the very least, fidelity and process data to capture the characteristics or design features that appeal most to postpartum women
Perfil da mortalidade na unidade de tratamento intensivo de adultos no Hospital de ClĂnicas de Porto Alegre
Analysis of factors influencing the ultrasonic fetal weight estimation
Objective: The aim of our study was the evaluation of sonographic fetal weight estimation taking into consideration 9 of the most important factors of influence on the precision of the estimation. Methods: We analyzed 820 singleton pregnancies from 22 to 42 weeks of gestational age. We evaluated 9 different factors that potentially influence the precision of sonographic weight estimation ( time interval between estimation and delivery, experts vs. less experienced investigator, fetal gender, gestational age, fetal weight, maternal BMI, amniotic fluid index, presentation of the fetus, location of the placenta). Finally, we compared the results of the fetal weight estimation of the fetuses with poor scanning conditions to those presenting good scanning conditions. Results: Of the 9 evaluated factors that may influence accuracy of fetal weight estimation, only a short interval between sonographic weight estimation and delivery (0-7 vs. 8-14 days) had a statistically significant impact. Conclusion: Of all known factors of influence, only a time interval of more than 7 days between estimation and delivery had a negative impact on the estimation
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