995 resultados para Sima, Guang, 1019-1086.
Resumo:
The SuperWASP cameras are wide-field imaging systems at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, and at the Sutherland Station of the South African Astronomical Observatory. Each instrument has a field of view of some 482 deg2 with an angular scale of 13.7" pixel-1, and is capable of delivering photometry with accuracy better than 1% for objects having V~7.0-11.5. Lower quality data for objects brighter than V~15.0 are stored in the project archive. The systems, while designed to monitor fields with high cadence, are capable of surveying the entire visible sky every 40 minutes. Depending on the observational strategy, the data rate can be up to 100 Gbytes per night. We have produced a robust, largely automatic reduction pipeline and advanced archive, which are used to serve the data products to the consortium members. The main science aim of these systems is to search for bright transiting exoplanet systems suitable for spectroscopic follow-up observations. The first 6 month season of SuperWASP-North observations produced light curves of ~6.7 million objects with 12.9 billion data points.
Resumo:
Oscillations in network bright points (NBPs) are studied at a variety of chromospheric heights. In particular, the three-dimensional variation of NBP oscillations is studied using image segmentation and cross-correlation analysis between images taken in light of Ca II K3, Ha core, Mg I b2, and Mg I b1-0.4 Å. Wavelet analysis is used to isolate wave packets in time and to search for height-dependent time delays that result from upward- or downward-directed traveling waves. In each NBP studied, we find evidence for kink-mode waves (1.3, 1.9 mHz), traveling up through the chromosphere and coupling with sausage-mode waves (2.6, 3.8 mHz). This provides a means for depositing energy in the upper chromosphere. We also find evidence for other upward- and downward-propagating waves in the 1.3-4.6 mHz range. Some oscillations do not correspond to traveling waves, and we attribute these to waves generated in neighboring regions.
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X-ray spectra of the late-type star AB Dor obtained with the XMM-Newton satellite are analyzed. AB Dor was particularly active during the observations. An emission measure reconstruction technique is employed to analyze flare and quiescent spectra, with emphasis on the Fe XVII 15 - 17 angstrom wavelength region. The Fe XVII 16.78 angstrom/ 15.01 angstrom line ratio increases significantly in the hotter flare plasma. This change in the ratio is opposite to the theoretical predictions and is attributed to the scattering of 15.01 angstrom line photons from the line of sight. The escape probability technique indicates an optical depth of approximate to 0.4 for the 15.01 angstrom line. During the flare, the electron density is 4.4(-1.6)(+2.7) x 10(10) cm(-3), and the fractional Fe abundance is 0.5 +/- 0.1 of the solar photospheric value Using these parameters, a path length of approximate to 8000 km is derived. There is no evidence of opacity in the quiescent X-ray spectrum of the star.
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Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory. For the first time, cospatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images and spectra were used to determine the flux of nonthermal electrons accelerated during the impulsive phase of an M2.2 flare. When we assumed a thick-target model, the injected electron spectrum was found to have a spectral index of similar to 7.3, a low-energy cutoff of similar to 20 keV, and a resulting flux of >= 4 x10(10) ergs cm(-2) s(-1). The dynamic response of the atmosphere was determined using CDS spectra; we found a mean upflow velocity of 230 +/- 38 km s(-1) in Fe (XIX) (592.23 angstrom) and associated downflows of 36 +/- 16 and 43 +/- 22 km s(-1) at chromospheric and transition region temperatures, respectively, relative to an averaged quiet- Sun spectra. The errors represent a 1 j dispersion. The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory.
Resumo:
Using a before and after study design, we compared protocolised weaning from mechanical ventilation with usual non-protocolised practice in intensive care. Outcomes (duration of mechanical ventilation, duration of intubation, intensive care stay) and complications (re-intubations, tracheostomy, mortality) were compared between baseline (Phase I) and following implementation of protocolised weaning (Phase II). Over the same period, we collected data in a second (reference) unit to monitor practice changes over time. In the intervention unit, outcomes were longer in Phase II compared with Phase I (all p < 0.005). When adjusted for admission APACHE II score and diagnostic category, only intensive care stay remained significantly longer (p = 0.002). There were significantly more tracheostomies in Phase II (p = 0.004). The reference unit demonstrated no statistically significant differences in study outcomes or complications between Phases. Protocolised weaning did not reduce the duration of mechanical ventilation and was not associated with an increased rate of re-intubation or intensive care unit mortality.
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In this paper we analyze the representation of the body in blogs by women with breast cancer. Taking into account both texts and images, we study the representation of the body on the basis of the body problems proposed by Frank (1995): control, body-relatedness, other-relatedness and desire. In the blogs studied we find a desiring and dyadic body, which is understood as part of a network of affection and care. The diagnosis of cancer can generate both dissociation, when the body is experienced as a threat, and association, a wish to be connected to it. In relation to control, a clear will of predictability is observed but traces of assumption of contingency also appear.
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Charge exchange X-ray and far-ultraviolet (FUV) aurorae can provide detailed insight into the interaction between solar system plasmas. Using the two complementary experimental techniques of photon emission spectroscopy and translation energy spectroscopy, we have studied state-selective charge exchange in collisions between fully ionized helium and target gasses characteristic of cometary and planetary atmospheres (H2O, CO2, CO, and CH4). The experiments were performed at velocities typical for the solar wind (200-1500 km s(-1)). Data sets are produced that can be used for modeling the interaction of solar wind alpha particles with cometary and planetary atmospheres. These data sets are used to demonstrate the diagnostic potential of helium line emission. Existing Extreme Ultraviolet Explorer (EUVE) observations of comets Hyakutake and Hale-Bopp are analyzed in terms of solar wind and coma characteristics. The case of Hale-Bopp illustrates well the dependence of the helium line emission to the collision velocity. For Hale-Bopp, our model requires low velocities in the interaction zone. We interpret this as the effect of severe post-bow shock cooling in this extraordinary large comet.
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Measurements of electron capture and ionization of O-2 molecules in collisions with H+ and O+ ions have been made over an energy range 10 - 100 keV. Cross sections for dissociative and nondissociative interactions have been separately determined using coincidence techniques. Nondissociative channels leading to O-2(+) product formation are shown to be dominant for both the H+ and the O+ projectiles in the capture collisions and only for the H+ projectiles in the ionization collisions. Dissociative channels are dominant for ionizing collisions involving O+ projectiles. The energy distributions of the O+ fragment products from collisions involving H+ and O+ have also been measured for the first time using time-of-flight methods, and the results are compared with those from other related studies. These measurements have been used to describe the interaction of the energetic ions trapped in Jupiter's magnetosphere with the very thin oxygen atmosphere of the icy satellite Europa. It is shown that the ionization of oxygen molecules is dominated by charge exchange plus ion impact ionization processes rather than photoionization. In addition, dissociation is predominately induced through excitation of electrons into high-lying repulsive energy states ( electronically) rather than arising from momentum transfer from knock-on collisions between colliding nuclei, which are the only processes included in current models. Future modeling will need to include both these processes.
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We report here the first detection of hectometer-size objects by the method of serendipitous stellar occultation. This method consists of recording the diffraction shadow created when an object crosses the observer's line of sight and occults the disk of a background star. One of our detections is most consistent with an object between Saturn and Uranus. The two other diffraction patterns detected are caused by Kuiper Belt objects beyond 100 AU from the Sun and hence are the farthest known objects in the solar system. These detections show that the Kuiper Belt is much more extended than previously believed and that the outer part of the disk could be composed of smaller objects than the inner part. This gives critical clues to understanding the problem of the formation of the outer planets of the solar system.
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The photometric and spectroscopic properties of 26 well-observed Type Ia Supernovae (SNe Ia) were analyzed with the aim of exploring SN Ia diversity. The sample includes (Branch) normal SNe, as well as extreme events such as SN 1991T and SN 1991bg, while the truly peculiar SNe Ia, SN 2000cx and SN 2002cx, are not included in our sample. A statistical treatment reveals the existence of three different groups. The first group (FAINT) consists of faint SNe Ia similar to SN 1991bg, with low expansion velocities and rapid evolution of Si II velocity. A second group consists of normal SNe Ia, also with high temporal velocity gradient (HVG), but with brighter mean absolute magnitude =-19.3 and higher expansion velocities than the FAINT SNe. The third group includes both normal and SN 1991T-like SNe Ia: these SNe populate a narrow strip in the Si II velocity evolution plot, with a low-velocity gradient (LVG), but have absolute magnitudes similar to HVGs. While the FAINT and HVG SNe Ia together seem to define a relation between R(Si II) and ���m15(B), the LVG SNe either do not conform to that relation or define a new, looser one. The R(Si II) premaximum evolution of HVGs is strikingly different from that of LVGs. We discuss the impact of this evidence on the understanding of SN Ia diversity, in terms of explosion mechanisms, degree of ejecta mixing, and ejecta-circumstellar material interaction.
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Winter is energetically challenging for small herbivores because of greater energy requirements for thermogenesis at a time when little energy is available. We formulated a model predicting optimal wintering body size, accounting for the scaling of both energy expenditure and assimilation to body size, and the trade-off between survival benefits of a large size and avoiding survival costs of foraging. The model predicts that if the energy cost of maintaining a given body mass differs between environments, animals should be smaller in the more demanding environments, and there should be a negative correlation between body mass and daily energy expenditure (DEE) across environments. In contrast, if animals adjust their energy intake according to variation in survival costs of foraging, there should be a positive correlation between body mass and DEE. Decreasing temperature always increases equilibrium DEE, but optimal body mass may either increase or decrease in colder climates depending on the exact effects of temperature on mass-specific survival and energy demands. Measuring DEE with doubly labeled water on wintering Microtus agrestis at four field sites, we found that DEE was highest at the sites where voles were smallest despite a positive correlation between DEE and body mass within sites. This suggests that variation in wintering body mass between sites was due to variation in food quality/availability and not adjustments in foraging activity to varying risks of predation.
Resumo:
Among the duties of the government bodies’ members of the different entities, which are connected to the good government, the duty of loyalty must be underlined. This duty, derived from the good-faith duty, obliges to act in the interest of the entity in case of conflict of interest, and to subordinate one’s own interests, except when there is an authorisation. Loyalty duty is applicable both to managers, who must manage the entity’s interest, and to partners, according to the common purpose derived from the company contract. This duty, at the same time, includes some particular rules, referred to transparency, remuneration, prohibition of competition, self-contracting... This essay compares the regulation of the duty of loyalty and its realizations in the different Cooperative Laws in Spain, both referring to the managers and to the partners, comparing this, at the same time, with the regulation of these aspects in companies’ general legislation, an in the Spanish Corporate Enterprises Act in particular, in order to obtain a general view of the issue, a necessary basis to go more deeply into it, and suggesting some preliminary conclusions or assessments.