443 research outputs found
P-T-t evolution of the Himalayan metamorphic core in the Mugu Karnali transect (Central Himalaya): preliminary data based on calculations of pseudosections
Abstract HKT-ISTP 2013
A
The Role of Inverse Compton Scattering in Solar Coronal Hard X-ray and Gamma-ray Sources
Coronal hard X-ray (HXR) and continuum gamma-ray sources associated with the
impulsive phase of solar flares have been the subject of renewed interest in
recent years. They have been interpreted in terms of thin-target, nonthermal
bremsstrahlung emission. This interpretation has led to rather extreme physical
requirements in some cases. For example, in one case, essentially all of the
electrons in the source must be accelerated to nonthermal energies to account
for the coronal HXR source. In other cases, the extremely hard photon spectra
of the coronal continuum gamma-ray emission suggest that the low energy cutoff
of the electron energy distribution lies in the MeV energy range. Here we
consider the role of inverse Compton scattering (ICS) as an alternate emission
mechanism in both the ultra- and mildly relativistic regimes. It is known that
relativistic electrons are produced during powerful flares; these are capable
of up-scattering soft photospheric photons to HXR and gamma-ray energies.
Previously overlooked is the fact that mildly relativistic electrons, generally
produced in much greater numbers in flares of all sizes, can up-scatter EUV/SXR
photons to HXR energies. We also explore ICS on anisotropic electron
distributions and show that the resulting emission can be significantly
enhanced over an isotropic electron distribution for favorable viewing
geometries. We briefly review results from bremsstrahlung emission and
reconsider circumstances under which nonthermal bremsstrahlung or ICS would be
favored. Finally, we consider a selection of coronal HXR and gamma-ray events
and find that in some cases the ICS is a viable alternative emission mechanism
Transient 3D simulations for the ASTRID Reactor: Preliminary Results for the ULOF initiation phase
The use of mobile phones for skin tumor screening
A lot of importance is attributed to mobile telemedicine these days, a topic that encompasses a wide and ever growing range of applications. Small, handheld devices such as camera mobile phones have come into every day use providing technically sophisticated tasks on a user-friendly level and can therefore be easily used in various fields of telemedicine. Dermatology is a perfect candidate for the use of telemedicine tools in general, as well as mobile devices in particular. The unique aspect of mobile teledermatology is that this system represents a filtering, or triage system, allowing a sensitive approach for the management of patients with emergent skin diseases. In order to investigate the feasibility of teleconsultation using a new generation of cellular phones, a clinical study to evaluate the accuracy of online diagnosis of skin tumours was conducted. Teledermoscopy represents a recent development of teledermatology that might add up additional information in the diagnosis of pigmented skin lesions. Teledermatology, mobile as well as stationary, can advance the reliability of diagnosis by expert consultations without expensive and time-consuming relocations. Consequently, the quality of patient's care can be raised and the costs of the health care system can be reduced
Genetic algorithm-based optimisation of the few-group structure for lead fast reactors analysis
The sub-arcsecond hard X-ray structure of loop footpoints in a solar flare
The newly developed X-ray visibility forward fitting technique is applied to
Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data of a limb
flare to investigate the energy and height dependence on sizes, shapes, and
position of hard X-ray chromospheric footpoint sources. This provides
information about the electron transport and chromospheric density structure.
The spatial distribution of two footpoint X-ray sources is analyzed using
PIXON, Maximum Entropy Method, CLEAN and visibility forward fit algorithms at
nonthermal energies from to keV. We report, for the first
time, the vertical extents and widths of hard X-ray chromospheric sources
measured as a function of energy for a limb event. Our observations suggest
that both the vertical and horizontal sizes of footpoints are decreasing with
energy. Higher energy emission originates progressively deeper in the
chromosphere consistent with downward flare accelerated streaming electrons.
The ellipticity of the footpoints grows with energy from at keV to at keV. The positions of X-ray emission are in
agreement with an exponential density profile of scale height ~km.
The characteristic size of the hard X-ray footpoint source along the limb is
decreasing with energy suggesting a converging magnetic field in the footpoint.
The vertical sizes of X-ray sources are inconsistent with simple collisional
transport in a single density scale height but can be explained using a
multi-threaded density structure in the chromosphere.Comment: 7 pages, 7 figures, submitted to Ap
Determination of hydraulic parameters in experimental soil columns from the southeast of Buenos Aires province
La cuenca del RÃo Quequén Grande
constituye una región representativa de
los sistemas agrÃcolas pampeanos. El
acuÃfero en esta región es la principal
fuente de abastecimiento de agua para
todos los usos, lo que pone de manifiesto
la importancia de desarrollar los elementos
necesarios para el estudio de la movilidad
de los contaminantes a través de los suelos
hacia la zona saturada. El objetivo del
presente trabajo fue obtener parámetros
hidráulicos bajo condiciones de saturación
en columnas intactas de distintos tipos de
suelos de la región, contemplando suelos
de uso agrÃcola y natural. Se estudiaron dos
series de suelo: Serie Azul y Serie Semillero
Buck, con muestras tomadas en dos sectores
próximos a las localidades de LoberÃa y La
Dulce, respectivamente. Las columnas fueron
eluidas con una solución acuosa de iones
cloruro y se midió el incremento progresivo
de conductividad. A partir de las curvas
de arribo obtenidas, se ajustó la ecuación
de transporte, obteniendo los valores de
dispersividad y porosidad. Dichos parámetros
no presentaron diferencias significativas
según el uso para los suelos de LoberÃa,
de textura franco arcillosa, indicando que
la labranza no producirÃa modificaciones
evidentes en el perfil del suelo. En La Dulce,
donde los suelos poseen una textura más
arenosa, los parámetros variaron según
el uso del suelo, presentando una mayor
dispersividad y menor porosidad del suelo
bajo explotación agrÃcola extensiva.The Quequén Grande river basin is
representative of the farming systems from the
Pampas region. The aquifer is the main source
of water supply for all uses, which highlights the
importance to study the mobility of contaminants
through the soil to the saturated zone. The aim
of this study was to obtain hydraulic parameters
of different soil types in the region according
to land use (agricultural and natural) under
saturated conditions. Two study areas were
selected close to the cities La Dulce (Azul Series
Soil) and LoberÃa (Semillero Buck Series Soil),
as representatives of the dominant soil types
in this area. The columns were eluted with an
aqueous solution containing chloride ions and
the progressive increase was measured at the
end of the column. From the experimental data
the breakthrough curve was adjusted using
MATLAB software while dispersivity and porosity
values were determined from modeled data.
These parameters did not differ significantly in
LoberÃa, so it is assumed that tillage does not
produce significant changes in the soil profile.
Conversely, in La Dulce land use affects the
hydraulic properties of the soil leading to lower
porosity and higher dispersivity values in soils
under tillage use.Fil: Grondona, Sebastián I..
Universidad Nacional de Mar del PlataFil: MartÃnez, Daniel E..
Universidad Nacional de Mar del PlataFil: Benavente, Miguel.
Universidad Nacional de Mar del PlataFil: Gonzalez, Mariana.
Universidad Nacional de Mar del PlataFil: Massone, Héctor E..
Universidad Nacional de Mar del PlataFil: Miglioranza, Karina S. B..
Universidad Nacional de Mar del Plat
Forward fitting STIX visibilities
Aims. We seek to determine to what extent the problem of forward fitting visibilities measured by the Spectrometer/Telescope Imaging X-rays (STIX) on board Solar Orbiter becomes more challenging with respect to the same problem in the case of previous hard X-ray solar imaging missions. In addition, we aim to identify an effective optimization scheme for parametric imaging for STIX. Methods. This paper introduces a global search optimization for forward-fitting STIX visibilities and compares its effectiveness with respect to the standard simplex-based optimization used so far for the analysis of visibilities measured by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). We made this comparison by considering experimental visibilities measured by both RHESSI and STIX, as weel as synthetic visibilities generated by accounting for the STIX signal formation model. Results. We found that among the three global search algorithms for parametric imaging, particle swarm optimization (PSO) exhibits the best performances in terms of both stability and computational effectiveness. This method is as reliable as the simplex method in the case of RHESSI visibilities. However, PSO is significantly more robust when applied to STIX simulated and experimental visibilities. Conclusions. A standard optimization based on local search of minima is not effective enough for forward-fitting the few visibilities sampled by STIX in the spatial frequency plane. Therefore, more sophisticated optimization schemes based on global search must be introduced for parametric imaging in the case of the Solar Orbiter X-ray telescope. The forward-fitting routine based on PSO proved to be significantly robust and reliable, and it could be considered as an effective candidate tool for parametric imaging in the STIX context
Melanoma Screening with Cellular Phones
Background. Mobile teledermatology has recently been shown to be suitable for teledermatology despite limitations in image definition in preliminary studies. The unique aspect of mobile teledermatology is that this system represents a filtering or triage system, allowing a sensitive approach for the management of patients with emergent skin diseases. Methodology/Principal Findings. In this study we investigated the feasibility of teleconsultation using a new generation of cellular phones in pigmented skin lesions. 18 patients were selected consecutively in the Pigmented Skin Lesions Clinic of the Department of Dermatology, Medical University of Graz, Graz (Austria). Clinical and dermoscopic images were acquired using a Sony Ericsson with a built-in two-megapixel camera. Two teleconsultants reviewed the images on a specific web application (http://www.dermahandy.net/default.asp) where images had been uploaded in JPEG format. Compared to the face-to-face diagnoses, the two teleconsultants obtained a score of correct telediagnoses of 89% and of 91.5% reporting the clinical and dermoscopic images, respectively. Conclusions/Significance. The present work is the first study performing mobile teledermoscopy using cellular phones. Mobile teledermatology has the potential to become an easy applicable tool for everyone and a new approach for enhanced self-monitoring for skin cancer screening in the spirit of the eHealth program of the European Commission Information for Society and Media
Avaliação algimétrica e sinérgica em cães tratados pela levomepromazina, induzidos pelo tiopental e mantidos pelo sevofluorano, pré-tratados ou não pelo butorfanol
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