6,585 research outputs found
Ca II 8542 \AA\ brightenings induced by a solar microflare
We study small-scale brightenings in Ca II 8542 \AA\ line-core images to
determine their nature and effect on localized heating and mass transfer in
active regions. High-resolution 2D spectroscopic observations of an active
region in the Ca II 8542 \AA\ line were acquired with the GFPI attached to the
1.5-meter GREGOR telescope. Inversions of the spectra were carried out using
NICOLE. We identified three brightenings of sizes up to 2"x2". We found
evidence that the brightenings belonged to the footpoints of a microflare (MF).
The properties of the observed brightenings disqualified the scenarios of
Ellerman bombs or IRIS bombs. However, this MF shared some common properties
with flaring active-region fibrils or flaring arch filaments (FAFs): (1) FAFs
and MFs are both apparent in chromospheric and coronal layers according to the
AIA channels, and (2) both show flaring arches with lifetimes of about 3.0-3.5
min and lengths of about 20". The inversions revealed heating by 600 K at the
footpoint location in the ambient chromosphere during the impulsive phase.
Connecting the footpoints, a dark filamentary structure appeared in the Ca II
line-core images. Before the start of the MF, the spectra of this structure
already indicated average blueshifts, meaning upward motions of the plasma
along the LOS. During the impulsive phase, these velocities increased up to
-2.2 km/s. Downflows dominated at the footpoints. However, in the upper
photosphere, slight upflows occurred during the impulsive phase. Hence,
bidirectional flows are present in the footpoints of the MF. Conclusions: We
detected Ca II brightenings that coincided with the footpoint location of an
MF. The MF event led to a rise of plasma in the upper photosphere, both before
and during the impulsive phase. Excess mass, previously raised to at most
chromospheric layers, slowly drained downward along arches toward the
footpoints of the MF.Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 6
figures, 1 online movi
Exploiting graphic processing units parallelism to improve intelligent data acquisition system performance in JET's correlation reflectometer
The performance of intelligent data acquisition systems relies heavily on their processing capabilities and local bus bandwidth, especially in applications with high sample rates or high number of channels. This is the case of the self adaptive sampling rate data acquisition system installed as a pilot experiment in KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. In order to do so it must transfer acquired data to a memory buffer in the host processor and run heavy computational algorithms for each data block. The processing capabilities of the host CPU and the bandwidth of the PXI bus limit the maximum sample rate that can be achieved, therefore limiting the maximum bandwidth of the phenomena that can be studied. Graphic processing units (GPU) are becoming an alternative for speeding up compute intensive kernels of scientific, imaging and simulation applications. However, integrating this technology into data acquisition systems is not a straight forward step, not to mention exploiting their parallelism efficiently. This paper discusses the use of GPUs with new high speed data bus interfaces to improve the performance of the self adaptive sampling rate data acquisition system installed on JET. Integration issues are discussed and performance evaluations are presente
Bayesian Inversion of Stokes Profiles
[abridged] Inversion techniques are the most powerful methods to obtain
information about the thermodynamical and magnetic properties of solar and
stellar atmospheres. In the last years, we have witnessed the development of
highly sophisticated inversion codes that are now widely applied to
spectro-polarimetric observations. The majority of these inversion codes are
based on the optimization of a complicated non-linear merit function. However,
no reliable and statistically well-defined confidence intervals can be obtained
for the parameters inferred from the inversions. A correct estimation of the
confidence intervals for all the parameters that describe the model is
mandatory. Additionally, it is fundamental to apply efficient techniques to
assess the ability of models to reproduce the observations and to what extent
the models have to be refined or can be simplified. Bayesian techniques are
applied to analyze the performance of the model to fit a given observed Stokes
vector. The posterior distribution, is efficiently sampled using a Markov Chain
Monte Carlo method. For simplicity, we focus on the Milne-Eddington approximate
solution of the radiative transfer equation and we only take into account the
generation of polarization through the Zeeman effect. However, the method is
extremely general and other more complex forward models can be applied. We
illustrate the ability of the method with the aid of academic and realistic
examples. We show that the information provided by the posterior distribution
turns out to be fundamental to understand and determine the amount of
information available in the Stokes profiles in these particular cases.Comment: 15 pages, 12 figures, accepted for publication in A&
Physiological characteristics of libero and central volleyball players
The aim of this study is to determine the intensity of effort in competition of the libero and central players by measuring heart rate and blood lactate. A sample of 30 players from 10 teams was used. Heart rate was measured by telemetry during the matches. Blood samples were obtained when there were substitutions for the players and about 300 samples were taken. Significant differences were observed in mean and maximal heart rate values between the central players and the libero (p<0.01). Mean and maximal heart rate values tended to decrease in the last sets in all the positions analysed. Higher levels have been observed in the libero when the set is lost than when it is won. (p<0.01). With regard to blood lactate, significant differences were found in mean values between the two central players and the libero (p<0.01). It was observed that 40.9% of all the blood lactate concentrations, regardless of the position, corresponded to values higher than 4 mmol•l-1, and 2.8% were above 8 mmol•l-1. These values are far higher than those found in earlier studies
Quality assurance of surface wind observations from automated weather stations
Meteorological data of good quality arc important for understanding both global and regional climates In this respect, great efforts have been made to evaluate temperature- and precipitation-related records This study summarizes the evaluations made to date of the quality of wind speed and direction records acquired at 41 automated weather stations in the northeast of the Iberian Peninsula Observations were acquired from 1992 to 2005 at a temporal resolution of 10 and 30 min A quality assurance system was imposed to select) the records for 1) manipulation errors associated with storage and management of the data. 2) consistency limits to to ensure that observations ale within their natural limits of variation, and 3) temporal consistency to assess abnormally low/high variations in the individual time series In addition. the most important biases of the dataset are analyzed and corrected wherever possible A total of 1 8% wind speed and 3 7% wind direction records was assumed invalid. pointing to specific problems in wind measurement The study not only tiles to contribute to the science with the creation of a wind damsel of unmoved quality. but it also reports on potential errors that could be plc:sent in other wind dataset
Forest plantations in Manabí (Ecuador): assessment of fragmentation and connectivity to support dry tropical forests conservation
In many tropical regions, national forests plantation programs have been promoted. Those plantations frequently contribute to habitat changes. However, the associated effects of forest plantations on habitat fragmentation and landscape connectivity are unclear. From 2008 to 2018, we examined land use changes, plantations, and deforestation of the Manabí province (Ecuador) provided by the Ecuadorian Ministry of the Environment. Four scenarios were created: (i) land uses in 2008, (ii) land uses in 2018, (iii) land uses in 2018 without deforestation, and iv) land uses in 2018 including reforestation. Fragmentation and connectivity metrics were analyzed using ArcGisPro and Graphad 2.6 software, respectively. Puma yagouaroundi was selected as the reference species. At regional scale, forest plantations had a significant effect on land uses changes and fragmentation during the study period. Forests decreased from 33.7% to 32.4% between 2008 and 2018, although other natural land uses, mostly those involving shrubs, increased by almost double (from 2.4% to 4.6%). Most of the deforestation affected native forests during this period, and most reforested areas in 2018 covered former agricultural land. Fragmentation decreased in the number of patches and increased in the average patch size. When considering reforestation, deforestation was higher than the reforested area (58 km2 of difference), increasing the number of patches but with smaller size. Reforestation increased connectivity with a higher number of links and distance, particularly in central and extreme northeast areas of Manabí province. The scenario without deforestation also increased connectivity for Puma yagouaroundi in the west part of the Manabí province. Our findings suggest that forest plantations contribute to forest conservation by increasing the connectivity between fragmented patches
Facies generadoras de carbón en el Westfaliense superior de la Cuenca Carbonífera Central Asturiana
La Cuenca Carbonífera Central Asturiana constituye una cuenca de antepais individualizada en la Zona Cantábrica durante el Carbonifero Superior coincidiendo con la máxima actividad de la orogenia Hercinica. Durante el Westfaliense, se acumularon en ella importantes volúmenes de material clástico procedentes de los relieves en elevación situados al W. Los abanicos aluviales costeros constituyeron unos sistemas deposicionales muy eficientes en la dispersión de estos materiales, generaron extensas cuñas clásticas en relación con las cuales se originaron capas de carbón explotables. En este trabajo se estudian varios litosomas de edad Westfaliense Superior que representan episodios progradantes de estos sistemas sobre ambientes marinos someros v de transición. El análisis e interpretación de sus facies y geometrías permite la reconstrucción de las condiciones ambientales en que se generaron las capas de carbón asociadas a cada una de las unidades estudiadas. Estas se desarrollaron: 1) en zonas marginales a los lóbulos progradantes y zonas interlóbulos y 2) sobre los mismos una vez que éstos fueron abandonados y previamente a su enterramiento
Crystallization and preliminary X-ray diffraction analysis of the N-terminal domain of Paenibacillus barcinonensis xylanase 10C containing the CBM22-1-CBM22-2 tandem
A construct containing the CBM22-1-CBM22-2 tandem forming the N-terminal domain of Paenibacillus barcinonensis xylanase 10C (Xyn10C) has been purified and crystallized. A xylan-binding function and an affinity for mixed [beta]-1,3/[beta]-1,4 glucans have previously been demonstrated for some members of the CBM22 family. The sequence of the tandem is homologous to the N-terminal domains found in several thermophilic enzymes. Crystals of this tandem were grown by the streak-seeding method after a long optimization strategy. The structure has been determined by molecular replacement to a resolution of 2.43 Å and refinement is under way. This study represents the first structure containing two contiguous CBM22 modules, which will contribute to a better understanding of the role that this multiplicity plays in fine-tuning substrate affinit
HIV and antiretroviral treatment knowledge gaps and psychosocial burden among persons living with HIV in Lima, Peru
This study aims to describe knowledge on HIV and antiretroviral (ARV) treatment and psychosocial factors among people living with HIV (PLWH) in Lima, Perú, to explore characteristics associated to this knowledge, and determine its impact on sustained viral suppression. A cross-sectional survey was conducted among 171 PLWH at the largest referral health care center in Lima. The psychosocial factors measured were depression, risk of alcoholism, use of illegal drugs and disclosure. A participant had "poor knowledge" when less than 80% of replies were correct. Sustained viral suppression was defined as two consecutive viral loads under 50 copies/mL. A total of 49% and 43% had poor HIV and ARV knowledge respectively; 48% of the study population screened positive for depression and 27% reported feeling unsupported by the person they disclosed to. The largest gaps in HIV and ARV knowledge were among 98 (57%) that did not recognize that HIV increased the risk of cancer and among 57 (33%) participants that did not disagree with the statement that taking a double dose of ARV if they missed one. Moderate depression was significantly associated to poor HIV and ARV knowledge. Non-disclosure and being on ARVs for less than 6 months were associated with not achieving sustained viral suppression. Our findings highlight important HIV and ARV knowledge gaps of PLWH and a high burden of psychosocial problems, especially of depression, among PLWH in Lima, Peru. Increasing knowledge and addressing depression and disclosure could improve care of PLWH
- …