182 research outputs found
Estado actual del estudio del sĂndrome de burnout en el deporte
El estudio del sĂndrome de burnout en el deporte comenzĂł en los años 80. Estos deportistas presentaban sĂntomas caracterizados por agotamiento emocional, despersonalizaciĂłn y baja realizaciĂłn personal. Como consecuencia llevaba a una disminuciĂłn progresiva de sus niveles de rendimiento deportivo, hasta ocasionar, en algunos casos, la retirada prematura de la prĂĄctica deportiva. Se hace una revisiĂłn de los estudios publicados desde el inicio del estudio de burnout en el deporte. El nĂșmero de estudios en esta ĂĄrea ha aumentado estos Ășltimos años, no obstante, quedan cuestiones apenas tratadas como programas de prevenciĂłn e intervenciĂłn, nuevos modelos teĂłricos y la importancia que puede tener las variables de personalidad en el origen y mantenimiento del sĂndrome
Performance of a day/night water heat storage system for heating and cooling of semi-closed greenhouses in mild winter climate
A novel system for heating/cooling greenhouses based on air/water heat exchangers connected to a thermally stratified water storage tank was tested in a small greenhouse compartment at the Experimental Station of the Cajamar Foundation in AlmerĂa, Spain. The system maintained a closed greenhouse (no natural ventilation) throughout the winter and spring during which a truss tomato crop was grown. Atmospheric CO2 concentration could be maintained during the daytime allowing for greater net photosynthesis in relation to a reference greenhouse in which traditional natural ventilation was used to control temperature and humidity. Three fine wire heat exchangers (FiwihexÂź) were installed 1 m above the crop when at full development. The heat exchangers allowed for a very efficient transfer of the sensible and latent heat accumulated in the compartment. During the winter, the daytime temperatures were maintained below the ventilation set point (30°C). During the night, the system was able to maintain temperatures above the heating set point (12°C), with stored warm water temperatures between 15 and 17°C after clear days. After cloudy days, with water temperatures between 11 and 13°C, the system could always keep a temperature gradient with the exterior of 4-6°C, enough to maintain greenhouse air temperatures above 8°C the entire night. When seasonal night air temperatures exceeded the heating set point, the hot water at the top of the tank was cooled to the wet bulb temperature by means of an open cooling tower. The cooled water was used for cooling the greenhouse, which allowed for closing the greenhouse for a longer period. The water condensate during the cooling mode, allowed for a high water saving and maintained the relative humidity very constant during the day (around 80%). During the night, humidity was kept at 90% without ever reaching saturation
Functional diversity of chemokines and chemokine receptors in response to viral infection of the central nervous system.
Encounters with neurotropic viruses result in varied outcomes ranging from encephalitis, paralytic poliomyelitis or other serious consequences to relatively benign infection. One of the principal factors that control the outcome of infection is the localized tissue response and subsequent immune response directed against the invading toxic agent. It is the role of the immune system to contain and control the spread of virus infection in the central nervous system (CNS), and paradoxically, this response may also be pathologic. Chemokines are potent proinflammatory molecules whose expression within virally infected tissues is often associated with protection and/or pathology which correlates with migration and accumulation of immune cells. Indeed, studies with a neurotropic murine coronavirus, mouse hepatitis virus (MHV), have provided important insight into the functional roles of chemokines and chemokine receptors in participating in various aspects of host defense as well as disease development within the CNS. This chapter will highlight recent discoveries that have provided insight into the diverse biologic roles of chemokines and their receptors in coordinating immune responses following viral infection of the CNS
Biology and fertility life table of Mahanarva fimbriolata (StÄl) (Hemiptera: Cercopidae) in sugarcane
Mahanarva fimbriolata (StĂ„l) (Hemiptera: Cercopidae) is the most important pest of sugarcane harvested without the use of fire to burn leaf trash. Its biology was studied for three generations in order to obtain basic information about its life cycle. A fertility life table was used to evaluate the quality of laboratory-reared insects. Data were obtained at a temperature of 25 ± 1ÂșC, RH of 70 ± 10%, and a 14-hour photophase. The incubation period lasted 21 days with a viability of 81%; the nymph stage had a duration of 37 days, with a 94% viability; the male and female longevities were 18 and 23 days, respectively, with a pre-oviposition period of 5 days and an oviposition period of 16 days, with a fecundity of 342 eggs, with a life-cycle (egg-adult) of 60 days. A net reproductive rate (Ro) of 131 females produced per female per generation was measured, with a finite rate of increase (lambda) of 1.085. The fertility life table proved to be adequate to be evaluate the quality of laboratory-reared M. fimbriolata populations.A cigarrinha-das-raĂzes, Mahanarva fimbriolata (StĂ„l) (Hemiptera: Cercopidae), Ă© considerada a principal praga da cana-de-açĂșcar colhida sem despalha a fogo no Brasil. Neste trabalho, estudou-se sua biologia por trĂȘs geraçÔes, visando obter informaçÔes bĂĄsicas sobre seu ciclo de vida. Para avaliar a qualidade dos insetos criados em laboratĂłrio utilizou-se a tabela de vida de fertilidade. Os dados foram obtidos sob temperatura de 25 ± 1ÂșC, UR de 70 ± 10% e fotofase de 14 horas. O perĂodo de incubação foi de 21 dias e a viabilidade de 81%; a duração da fase ninfal foi de 37 dias, com viabilidade de 94%; as longevidades de machos e de fĂȘmeas foram de 18 e 23 dias respectivamente, com perĂodo de prĂ©-oviposição de 5 dias e oviposição de 16 dias, com fecundidade de 342 ovos, com duração do ciclo de vida (ovo-adulto) de 60 dias. A taxa lĂquida de reprodução (Ro) foi de 131 fĂȘmeas geradas por fĂȘmea por geração e a taxa finita de aumento (lambda) de 1,085. A tabela de vida de fertilidade mostrou-se adequada para avaliar a qualidade de populaçÔes de M. fimbriolata mantidas em criação de laboratĂłrio
The exposure of the hybrid detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays.
It consists of a surface array to measure secondary particles at ground level
and a fluorescence detector to measure the development of air showers in the
atmosphere above the array. The "hybrid" detection mode combines the
information from the two subsystems. We describe the determination of the
hybrid exposure for events observed by the fluorescence telescopes in
coincidence with at least one water-Cherenkov detector of the surface array. A
detailed knowledge of the time dependence of the detection operations is
crucial for an accurate evaluation of the exposure. We discuss the relevance of
monitoring data collected during operations, such as the status of the
fluorescence detector, background light and atmospheric conditions, that are
used in both simulation and reconstruction.Comment: Paper accepted by Astroparticle Physic
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass . Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report
Numbe
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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