953 research outputs found
Modelling solar low-lying cool loops with optically thick radiative losses
We investigate the increase of the DEM (differential emission measure)
towards the chromosphere due to small and cool magnetic loops (height
~Mm, ~K). In a previous paper we analysed the
conditions of existence and stability of these loops through hydrodynamic
simulations, focusing on their dependence on the details of the optically thin
radiative loss function used. In this paper, we extend those hydrodynamic
simulations to verify if this class of loops exists and it is stable when using
an optically thick radiative loss function. We study two cases: constant
background heating and a heating depending on the density. The contribution to
the transition region EUV output of these loops is also calculated and
presented. We find that stable, quasi-static cool loops can be obtained by
using an optically thick radiative loss function and a background heating
depending on the density. The DEMs of these loops, however, fail to reproduce
the observed DEM for temperatures between . We also show the
transient phase of a dynamic loop obtained by considering constant heating rate
and find that its average DEM, interpreted as a set of evolving dynamic loops,
reproduces quite well the observed DEM.Comment: Accepted for publication in A&A on Aug 21st 2015. arXiv admin note:
text overlap with arXiv:1112.030
Direct calorimetric measurements of isothermal entropy change on single crystal W-type hexaferrites at the spin reorientation transition
We report on the magnetic field induced isothermal entropy change, \Delta
s(Ha, T), of W-type ferrite with CoZn substitution. Entropy measurements are
performed by direct calorimetry. Single crystals of the composition
BaCoZnFeO, prepared by the flux method, are measured at
different fixed temperatures under an applied field perpendicular and parallel
to the c axis. At 296 K one deduces a value of K = 8.7 \times 10^{4} J
m for the first anisotropy constant, which is in good agreement with the
literature. The spin reorientation transition temperature is estimated to take
place between 200 and 220 K
Repetitive transcranial magnetic stimulation reduces remote apoptotic cell death and inflammation after focal brain injury.
After focal brain injuries occur, in addition to the effects that are attributable to the primary site of damage, the resulting functional impairments depend highly on changes that occur in regions that are remote but functionally connected to the site of injury. Such effects are associated with apoptotic and inflammatory cascades and are considered to be important predictors of outcome. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique that is used to treat various central nervous system (CNS) pathologies and enhance functional recovery after brain damage.
OBJECTIVE:
This study examined the efficacy of rTMS in mitigating remote degeneration and inflammation and in improving functional recovery in a model of focal brain damage.
METHODS:
Rats that were undergoing hemicerebellectomy (HCb) were treated with an rTMS protocol for 7 days, and neuronal death indices, glial activation, and functional recovery were assessed.
RESULTS:
rTMS significantly reduced neuronal death and glial activation in remote regions and improved functional recovery.
CONCLUSIONS:
Our finding opens up a completely new scenario for exploiting the potential of rTMS as an anti-apoptotic and anti-inflammatory treatment
Comparing extrapolations of the coronal magnetic field structure at 2.5 solar radii with multi-viewpoint coronagraphic observations
The magnetic field shapes the structure of the solar corona but we still know
little about the interrelationships between the coronal magnetic field
configurations and the resulting quasi-stationary structures observed in
coronagraphic images (as streamers, plumes, coronal holes). One way to obtain
information on the large-scale structure of the coronal magnetic field is to
extrapolate it from photospheric data and compare the results with
coronagraphic images. Our aim is to verify if this comparison can be a fast
method to check systematically the reliability of the many methods available to
reconstruct the coronal magnetic field. Coronal fields are usually extrapolated
from photospheric measurements typically in a region close to the central
meridian on the solar disk and then compared with coronagraphic images at the
limbs, acquired at least 7 days before or after to account for solar rotation,
implicitly assuming that no significant changes occurred in the corona during
that period. In this work, we combine images from three coronagraphs
(SOHO/LASCO-C2 and the two STEREO/SECCHI-COR1) observing the Sun from different
viewing angles to build Carrington maps covering the entire corona to reduce
the effect of temporal evolution to ~ 5 days. We then compare the position of
the observed streamers in these Carrington maps with that of the neutral lines
obtained from four different magnetic field extrapolations, to evaluate the
performances of the latter in the solar corona. Our results show that the
location of coronal streamers can provide important indications to discriminate
between different magnetic field extrapolations.Comment: Accepted by A&A the 20th of May, 201
Serum Vitamin D as a Biomarker in Autoimmune, Psychiatric and Neurodegenerative Diseases
Vitamin D is a steroid hormone regulating calcium-phosphorus homeostasis, immune response and brain function. In the past thirty years, an increasing number of cohort studies, meta-analyses and randomized controlled trials (RTCs) evaluated the serum levels of 25-hydroxyvitamin D [25(OH)D], which is considered the Vitamin D status biomarker, in patients affected by neurological, psychiatric and autoimmune diseases. Although an association between low 25(OH)D serum levels and the prevalence of these diseases has been found, it is still unclear whether the serum 25(OH)D measurement can be clinically useful as a biomarker for diagnosis, prognosis and predicting treatment response in neurodegeneration, mental illness and immune-mediated disorders. The lack of standardized data, as well as discrepancies among the studies (in the analytical methods, cut-offs, endpoints and study sets), weakened the findings achieved, hindered pooling data, and, consequently, hampered drawing conclusions. This narrative review summarizes the main findings from the studies performed on serum 25(OH)D in neurological, psychiatric and autoimmune diseases, and clarifies whether or not serum 25(OH)D can be used as a reliable biomarker in these diseases
Cofradías de esclavos negros, morenos y mulatos libres en la Catedral de Santo Domingo, Primada de América
The evangelization of the indigenous and spiritual assistance to the colonizers and Creoles, was a priority in the conquest and colonization of the Indies. The black slave was also evangelized but with different strategies, one of them was the brotherhood, which was installed in the churches and fulfilled an essential function giving the slave participation in religious and social events. For this reason, the objective of this research is to describe the brotherhoods of blacks, brunettes and mulattos that existed in the Cathedral of Santo Domingo, its composition and religious syncretism.La evangelización del indígena y la asistencia espiritual a los colonizadores y criollos fue prioridad en la conquista y colonización, de las Indias. El esclavo negro, también fue evangelizado, pero con estrategias diferentes, siendo una de ellas las cofradías, que se instalaron en las iglesias y cumplieron una función esencial dándole participación al esclavo en eventos religiosos y sociales. Por tal motivo, el objetivo de esta investigación es describir las cofradías de negros, morenos y mulatos que existieron en la Catedral de Santo Domingo, su composición y el sincretismo religioso
Air pollution and related respiratory diseases: the experience of a Local Health Authority in Liguria (North Italy)
Background. Numerous epidemiological studies have shown that air pollution due to both industry and heavy traffic has short- and long-term effects on health. The study was carried out in an industrial area with heavy urban and motorway traffic in the Province of Genoa (Italy).
Methods. The study was carried out from June 2005 to July 2008. An epidemiologic study was conducted by monitoring an elementary/ middle school situated in an area of recent industrial development and an elementary/middle school located in an area free from sources of industrial pollution. Furthermore, we conducted an investigation of workers in commercial premises situated in one area of heavy vehicular traffic. In the study areas, environmental monitoring campaigns were carried out in order to determine the association between indoor and outdoor pollution and respiratory disorders.
Results and discussion. The study did not bring to light any specific health problems attributable with certainty to industrial emissions. The impact of pollution caused by motor traffic proved to be greater than that due to industrial emissions. More exhaustive sampling campaigns should be implemented in order to quantify the effects of specific sources of emissions and to correlate these sources with pollutants (industry, urban traffic, motorway traffic)
Cannabinoid CB2 receptor (CB2R) stimulation delays rubrospinal mitochondrial-dependent degeneration and improves functional recovery after spinal cord hemisection by ERK1/2 inactivation.
Spinal cord injury (SCI) is a devastating condition of CNS that often results in severe functional impairments for which there are no restorative therapies. As in other CNS injuries, in addition to the effects that are related to the primary site of damage, these impairments are caused by degeneration of distal regions that are connected functionally to the primary lesion site. Modulation of the endocannabinoid system (ECS) counteracts this neurodegeneration, and pharmacological modulation of type-2 cannabinoid receptor (CB2R) is a promising therapeutic target for several CNS pathologies, including SCI. This study examined the effects of CB2R modulation on the fate of axotomized rubrospinal neurons (RSNs) and functional recovery in a model of spinal cord dorsal hemisection (SCH) at the cervical level in rats. SCH induced CB2R expression, severe atrophy, and cell death in contralateral RSNs. Furthermore, SCH affected molecular changes in the apoptotic cascade in RSNs - increased cytochrome c release, apoptosome formation, and caspase-3 activity. CB2R stimulation by its selective agonist JWH-015 significantly increased the bcl-2/bax ratio, reduced cytochrome c release, delayed atrophy and degeneration, and improved spontaneous functional recovery through ERK1/2 inactivation. These findings implicate the ECS, particularly CB2R, as part of the endogenous neuroprotective response that is triggered after SCI. Thus, CB2R modulation might represent a promising therapeutic target that lacks psychotropic effects and can be used to exploit ECS-based approaches to counteract neuronal degeneration
Thermal Behavior Assessment of Two Types of Roofs of the Dominican Vernacular Housing
The Dominican vernacular architecture, based on the indigenous bohio with Spanish influence, is built with natural materials, such as the royal palm (Roystonea Hispaniolana) and the cana palm (Sabal Dominguensis). This model of housing has remained practically unchanged for five centuries, responding adequately to the Caribbean tropical climate. In the twentieth century, start to replace the traditional palm leaf roof by a corrugated sheet zinc, significantly affecting the temperature inside these houses and altering the conditions of living comfort. For this reason, the aim of this research is to evaluate the thermal behavior of two roof types of vernacular housing. One type is a cana palm leaf roof and the other is a corrugated sheet zinc roof. The houses are in the towns of Villa Sombrero and Sabana Buey, Peravia Province, in the southwest of the Dominican Republic, a region with a Tropical savanna climate (Aw) according to the Köppen-Geiger climate classification. The climate is characterized by temperatures from 20°C to 38°C, with rainfall below 500 mm per year. The technique and tools used for this research are: Infrared Thermography (IRT) and digital thermometer for measure of thermal properties of roof materials, a thermometer and hygrometer to measure the relative humidity and temperature inside and outside of the houses, and carbon monoxide (CO) and carbon dioxide (CO2) meter. Passive IRT is used to measures the temperature differences of a structure that are generated under normal conditions. The results indicate that there is a difference in temperature between one type of roofing material and the other. Finding that houses with palm leaf roofs have lower temperature than corrugated sheet zinc roof and present a temperature difference between the interior and exterio
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