3,030 research outputs found
Determining the venting efficiency of simple chimneys for buoyant plumes
We present preliminary results from an examination of the capture and venting of a buoyant plume by a chimney. The aim is to enable improved management of indoor pollutant sources – for instance, the plume rising from a cooking pan in a kitchen or a cooking fire in a hut. Using the principle of dynamic similarity, we precise ly and controllably model the behaviour of indoor plumes by using saline solutions ejected into an enclosure containing freshwater. These well - established laboratory analogue techniques enable the location and concentration of tracer in the plume to be eas ily tracked, reflecting the evolution of pollutants carried in the plume. Focusing on a plume within a room containing a quiescent ambient environment, we identify two physical mechanisms potentially responsible for driving the removal of pollutants. The f irst, we describe as the capture of the plume, a process driven by the direct interaction between the plume and the evacuation opening; the second, we describe as the draining flow driven by a buoyant layer of fluid which may accumulate at the ceiling and is then evacuated through the effects of buoyancy. We first demonstrate that the addition of a simple cylindrical chimney that hangs downwards from an opening in the (analogue) ceiling increases the venting efficiency of these potentially polluting plumes. We go on to examine how the capture efficiency of these simple chimneys varies as the relative size of the plume and the chimney are altered, and demonstrate that simple model can provide predictions of the observed variation in capture efficiency
Controlo dos fatores de risco nos doentes hipertensos : uma tarefarit a cumprir
© 2019 Sociedade Portuguesa de Cardiologia. Published by Elsevier España, S.L.U. This is an open access article under CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)Cardiovascular (CV) disease is the leading cause of death in the Portuguese population, accounting for 29.8% of deaths in 2016, mainly due to stroke (10.6%) and coronary heart disease (CHD) (10.5%). Hypertension is the single most important risk factor for CV disease. In Portugal, its prevalence is high (approximately 42%), as demonstrated in previous studies, increases with age, and is usually associated with other risk factors and comorbidities.info:eu-repo/semantics/publishedVersio
Lp(a) como um novo alvo terapêutico na prevenção da doença cardiovascular : uma luz ao fundo do túnel?
© 2019 Sociedade Portuguesa de Cardiologia. Published by Elsevier España, S.L.U. This is an open access article under CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)Research on the importance of lipoprotein(a) [Lp(a)] gained new momentum when it became a potential therapeutic target. Our understanding of this mysterious circulating lipoprotein particle has undergone advances and setbacks since its discovery in 1963 by Kåre Berg’s group.1 Lp(a) is composed of liver-derived apolipoprotein A and apolipoprotein B-100, and has a similar structure to both low-density lipoprotein cholesterol (LDL-C) and plasminogen. Lp(a) thus has a proatherogenic and a prothrombotic component, and is associated with the pathogenesis of cardiovascular disease (CVD).info:eu-repo/semantics/publishedVersio
The impact of kinetic effects on the properties of relativistic electron-positron shocks
We assess the impact of non-thermally shock-accelerated particles on the
magnetohydrodynamic (MHD) jump conditions of relativistic shocks. The adiabatic
constant is calculated directly from first principle particle-in-cell
simulation data, enabling a semi-kinetic approach to improve the standard fluid
model and allowing for an identification of the key parameters that define the
shock structure. We find that the evolving upstream parameters have a stronger
impact than the corrections due to non-thermal particles. We find that the
decrease of the upstream bulk speed yields deviations from the standard MHD
model up to 10%. Furthermore, we obtain a quantitative definition of the shock
transition region from our analysis. For Weibel-mediated shocks the inclusion
of a magnetic field in the MHD conservation equations is addressed for the
first time
Canção no exílio: trajetória, sons e política no Cone Sul.
Com o Golpe Civil-Militar em 1964, o Brasil passou a viver uma experiência não tão
comum, a do exílio. Imediatamente ao início desta ditadura uma primeira leva de exilados
afastou do país brasileiros de destacada atuação, como profissionais liberais, políticos,
intelectuais e professores. Já conhecidos em suas atividades no Brasil e mesmo no exterior,
foram contratados por Universidades e diferentes órgãos não governamentais de diferentes
países. No exterior, realizaram atividades de denúncia contra a ditadura e criaram redes de
informação para abastecer de notícias sobre as ações da ditadura brasileira, particularmente,
sobre a repressão política e a censura.Organização, execução e patrocínio: UNILA e Itaipu-Paraguay - Parceria: NELOOL/UFSC & Universidad de VIG
Exploring the nature of collisionless shocks under laboratory conditions
Collisionless shocks are pervasive in astrophysics and they are critical to
understand cosmic ray acceleration. Laboratory experiments with intense lasers
are now opening the way to explore and characterise the underlying
microphysics, which determine the acceleration process of collisionless shocks.
We determine the shock character - electrostatic or electromagnetic - based on
the stability of electrostatic shocks to transverse electromagnetic
fluctuations as a function of the electron temperature and flow velocity of the
plasma components, and we compare the analytical model with particle-in-cell
simulations. By making the connection with the laser parameters driving the
plasma flows, we demonstrate that shocks with different and distinct underlying
microphysics can be explored in the laboratory with state-of-the-art laser
systems
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