1,196 research outputs found
Coronal loop hydrodynamics. The solar flare observedon November 12 1980 revisited: the UV line emission
We revisit a well-studied solar flare whose X-ray emission originating from a
simple loop structure was observed by most of the instruments on board SMM on
November 12 1980. The X-ray emission of this flare, as observed with the XRP,
was successfully modeled previously. Here we include a detailed modeling of the
transition region and we compare the hydrodynamic results with the UVSP
observations in two EUV lines, measured in areas smaller than the XRP rasters,
covering only some portions of the flaring loop (the top and the foot-points).
The single loop hydrodynamic model, which fits well the evolution of coronal
lines (those observed with the XRP and the \FeXXI 1354.1 \AA line observed with
the UVSP) fails to model the flux level and evolution of the \OV 1371.3 \AA
line.Comment: A&A, in press, 6 pages, 5 figure
A Statistical Approach for Improving the Performance of a Testing Methodology for Measurement Software
This paper describes the significant enhancements brought to an original methodology designed for testing measurement software.
In a previous paper, the authors proposed a blackbox seven-step procedure that allows the functional verification of complex instrument software to be performed.
The main features of the procedure are concerned with the following: 1) the ability of reproducing actual correlations among the software inputs and 2) the need for a limited number of test cases.Making use of innovative statistical techniques, themethodology performance and reliability have been enhanced.
Two further steps have been added with the aim of improving the correlation coefficient assessments and providing the estimations with a confidence level. Finally, a new strategy has been studied to optimize the number of test cases.
The effects of the new solutions on the performance of the methodology are evaluated by applying the procedure to a complex softwaremodule employed in an automotive system. A comparison with the previous methodology version is also reported
Experience with the Platelia Candida ELISA for the diagnosis of invasive candidosis in neonatal patients
ABSTRACTThis preliminary study evaluated the use of the Platelia Candida antigen kit for the diagnosis of invasive candidosis in 70 of 184 pre-term infants admitted to a neonatal intensive care unit between March 2004 and March 2006. The frequency of confirmed candidaemia was 6.5%. The sensitivity and specificity of the assay were 94.4% and 94.2%, respectively, with a positive predictive value of 85% and a negative predictive value of 98%. These results suggest that the inclusion of regular serological surveillance for mannanaemia in some pre-term infants would complement blood cultures for the early detection of candidosis
The three-body recombination of a condensed Bose gas near a Feshbach resonance
In this paper, we study the three-body recombination rate of a homogeneous
dilute Bose gas with a Feshbach resonance at zero temperature. The ground state
and excitations of this system are obtained. The three-body recombination in
the ground state is due to the break-up of an atom pair in the quantum
depletion and the formation of a molecule by an atom from the broken pair and
an atom from the condensate. The rate of this process is in good agreement with
the experiment on Na in a wide range of magnetic fields.Comment: 10 pages, 2 figures, to be published in Phys. Rev.
Experiments on fertilization of no-till systems in the brazilian Cerrado. Part I. potash fertilization of cover crops and its potential for the following soybean crop.
Since the 1970s, when Brazilian farmers started to practice no-till in the state of Parana, this form of cultivation has spread rapidly throughout the country. It currently accounts for approximately 26 million ha, or more than 40 percent of the total national area under seasonal crops (FEBRAPDP, 2008). The rapid expansion of no-till across states, which are the main producers of soybean and maize (Parana, Santa Catarina, Rio Grande do Sul in the Southern region and Goias, Mato Grosso, Mato Grosso do Sul in the Central-Western region of the country), has meant that Brazil has become one of the world’s leaders in no -till practice, approaching that of the acreage in the United States of America in 2005/2006
Combined Bulk and Surface Radiation Damage Effects at Very High Fluences in Silicon Detectors: Measurements and TCAD Simulations
In this work we propose a new combined TCAD radiation damage modelling
scheme, featuring both bulk and surface radiation damage effects, for the
analysis of silicon detectors aimed at the High Luminosity LHC. In particular,
a surface damage model has been developed by introducing the relevant
parameters (NOX, NIT) extracted from experimental measurements carried out on
p-type substrate test structures after gamma irradiations at doses in the range
10-500 Mrad(Si). An extended bulk model, by considering impact ionization and
deep-level cross-sections variation, was included as well. The model has been
validated through the comparison of the simulation findings with experimental
measurements carried out at very high fluences (2 10^16 1 MeV equivalent
n/cm^2) thus fostering the application of this TCAD approach for the design and
optimization of the new generation of silicon detectors to be used in future
HEP experiments.Comment: 8 pages, 14 figures. arXiv admin note: text overlap with
arXiv:1611.1013
Emotionotopy in the human right temporo-parietal cortex
AbstractHumans use emotions to decipher complex cascades of internal events. However, which mechanisms link descriptions of affective states to brain activity is unclear, with evidence supporting either local or distributed processing. A biologically favorable alternative is provided by the notion of gradient, which postulates the isomorphism between functional representations of stimulus features and cortical distance. Here, we use fMRI activity evoked by an emotionally charged movie and continuous ratings of the perceived emotion intensity to reveal the topographic organization of affective states. Results show that three orthogonal and spatially overlapping gradients encode the polarity, complexity and intensity of emotional experiences in right temporo-parietal territories. The spatial arrangement of these gradients allows the brain to map a variety of affective states within a single patch of cortex. As this organization resembles how sensory regions represent psychophysical properties (e.g., retinotopy), we propose emotionotopy as a principle of emotion coding
X-ray emission from dense plasma in CTTSs: Hydrodynamic modeling of the accretion shock
High spectral resolution X-ray observations of CTTSs demonstrate the presence
of plasma at T~2-3X10^6 K and n_e~10^11-10^13 cm^-3, unobserved in
non-accreting stars. Stationary models suggest that this emission is due to
shock-heated accreting material, but they do not allow to analyze the stability
of such material and its position in the stellar atmosphere. We investigate the
dynamics and the stability of shock-heated accreting material in CTTSs and the
role of the stellar chromosphere in determining the position and the thickness
of the shocked region. We perform 1-D HD simulations of the impact of the
accretion flow onto chromosphere of a CTTS, including the effects of gravity,
radiative losses from optically thin plasma, thermal conduction and a well
tested detailed model of the stellar chromosphere. Here we present the results
of a simulation based on the parameters of the CTTS MP Mus. We find that the
accretion shock generates an hot slab of material above the chromosphere with a
maximum thickness of 1.8X10^9 cm, density n_e~10^11-10^2 cm^-3, temperature
T~3X10^6 K and uniform pressure equal to the ram pressure of the accretion flow
(~450 dyn cm^-2). The base of the shocked region penetrates the chromosphere
and stays where the ram pressure is equal to the thermal pressure. The system
evolves with quasi-periodic instabilities of the material in the slab leading
to cyclic disappearance and re-formation of the slab. For an accretion rate of
~10^-10 M_sun yr^-1, the shocked region emits a time-averaged X-ray luminosity
L_X~7X10^29 erg s^-1, which is comparable to the X-ray luminosity observed in
CTTSs of the same mass. Furthermore, the X-ray spectrum synthesized from the
simulation matches in detail all the main features of the O VIII and O VII
lines of the star MP Mus.Comment: Accepted for publication as a Letter in Astronomy & Astrophysic
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