1,961 research outputs found
Valoración biomecánica de la acción de los brazos y pierna libre en saltadores de altura de élite
El objetivo del presente estudio ha sido cuantificar cómo los saltadores de altura de élite
utilizan sus brazos y pierna libre para incrementar la velocidad vertical del centro de gravedad en
el despegue. Este estudio ha sido llevado a cabo sobre una muestra de seis saltadores utilizando el
análisis cinematográfico tridimensional y aplicando el método del momento relativo (Lees, A. y
Barton, G. 1996) para valorar la acción de los segmentos libres. Los valores de los picos del
momento relativo han sido, del brazo más cercano a la barra de 9.3 kg m s-1, del brazo más lejano
11.2 kg m s-1 y la pierna libre 17.4 kg m s-1. En el momento inicial de la batida la pierna libre ha
obtenido un momento relativo positivo en contraste con el momento negativo que obtenían los
brazos. Durante la batida el momento relativo alcanzó un pico de 40.31 kg m s-1, en el 63% del
tiempo que duró la batida. Los brazos han tenido una mayor contribución al momento relativo final
del cuerpo que la pierna libre debido al mayor incremento que se ha producido en el momento
relativo durante la batida.
Las diferencias en el momento generado por los segmentos y el momento total del cuerpo alcanzó
el 9.3 %, valor que ha sido considerado como la contribución de los segmentos libres al rendimiento
del salto.
Palabras Clave: Salto de altura, análisis biomecánico, momento relativo
Recent activity of the Be/X-ray binary system SAX J2103.5+4545
Aims. We present a multiwavelength study of the Be/X-ray binary system SAX
J2103.5+4545 with the goal of better characterizing the transient behaviour of
this source.
Methods. SAX J2103.5+4545 was observed by Swift-XRT four times in 2007 from
April 25 to May 5, and during quiescence in 2012 August 31. In addition, this
source has been monitored from the ground-based astronomical observatories of
El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain) and Sierra
Nevada (Granada, Spain) since 2011 August, and from the TUBITAK National
Observatory (Antalya, Turkey) since 2009 June. We have performed spectral and
photometric temporal analyses in order to investigate the different states
exhibited by SAX J2103.5+4545.
Results. In X-rays, an absorbed power law model provided the best fit for all
the XRT spectra. An iron-line feature at ~6.42 keV was present in all the
observations except for that taken during quiescence in 2012. The photon
indexes are consistent with previous studies of SAX J2103.5+4545 in high/low
luminosity states. Pulsations were found in all the XRT data from 2007
(2.839(2) mHz; MJD 54222.02), but not during quiescence. Both optical outbursts
in 2010 and 2012 lasted for about 8/9 months (as the one in 2007 probably did
and the current one in 2014 might do) and were most probably caused by mass
ejection events from the Be star that eventually fed the circumstellar disc.
All of these outbursts started about 3 months before the triggering of the
X-ray activity, and about the same period before the maximum of the H_alpha
line equivalent width (in emission) was reached at only ~ -5 \AA. In this work
we found that the global correlation between the BV variability and the X-ray
intensity was also observed at longer wavelengths in the IR domain.Comment: 11 pages, 7 figures, and online material (2 tables). Submitted to A&A
in 2014 Januar
Utilization of slaughter-house by products as nitrogen source for filamentous fungi in submerged fermentation, with simultaneous deodorization
Proton radiation effect on InAs avalanche photodiodes
With increasing interest over the past decade in space-related remote sensing and communications using near-infrared (NIR) wavelengths, there is a need for radiation studies on NIR avalanche photodiodes (APDs), due to the high radiation environment in space. In this work, we present an experimental study of proton radiation effects on performance parameters of InAs APDs, whose sensitivity extends from visible light to ∼3.5 μm. Three irradiation energies (10.0, 31.4, and 58.8 MeV) and four fluences (109 to 1011 p/cm2) were used. At the harshest irradiation condition (10.0 MeV energy and 1011 p/cm2 fluence) the APDs' avalanche gain and leakage current showed a measurable degradation. However, the responsivity of the APDs was unaffected under all conditions tested. The data reported in this article is available from the figshare digital repository (DOI: https://dx.doi.org/10.15131/shef.data.4560562)
Voxel based stochastic modeling of complex materials
In the present study an object oriented stochastic approach is proposed for the construction of synthetic, computational models of complex materials. The conventional approach to model and study materials mechanics will be outlined, indicating its limitations to deal with complex heterogeneous materials. The proposed object oriented integrative modeling will be explained emphasizing its advantages compared to continuum mechanics when dealing with complex materials. Finally, the stochastic assembly of complex materials synthetic samples is described and the architecture of the 3M2S (multiphysics materials modeling and simulation system) is shown, indicating further work based on 3M2s
Voxel based stochastic modeling of complex materials
In the present study an object oriented stochastic approach is proposed for the construction of synthetic, computational models of complex materials. The conventional approach to model and study materials mechanics will be outlined, indicating its limitations to deal with complex heterogeneous materials. The proposed object oriented integrative modeling will be explained emphasizing its advantages compared to continuum mechanics when dealing with complex materials. Finally, the stochastic assembly of complex materials synthetic samples is described and the architecture of the 3M2S (multiphysics materials modeling and simulation system) is shown, indicating further work based on 3M2s
Detection of a large Be circumstellar disk during X-ray quiescence of XTE J1946+274
We present a multiwavelength study of the Be/X-ray binary system XTE
J1946+274 with the main goal of better characterizing its behavior during X-ray
quiescence. We aim to shed light on the mechanism which triggers the X-ray
activity for this source. XTE J1946+274 was observed by Chandra-ACIS during
quiescence in 2013 March 12. In addition, this source has been monitored from
the ground-based astronomical observatories of El Teide (Tenerife, Spain),
Roque de los Muchachos (La Palma, Spain) and Sierra Nevada (Granada, Spain)
since 2011 September, and from the TUBITAK National Observatory (Antalya,
Turkey) since 2005 April. We have performed spectral and photometric temporal
analyses in order to investigate the quiescent state and transient behavior of
this binary system. In 2006, a long mass ejection event took place from the Be
star, lasting for about seven years. We also found that a large Be
circumstellar disk was present during quiescence, although major X-ray activity
was not observed. We made an attempt to explain this scenario by assuming the
permanently presence of a tilted and warped Be circumstellar disk. The 0.3-10
keV X-ray spectrum during quiescence was well fitted with either an absorbed
blackbody or absorbed power-law models. The main parameters obtained for these
models were kT=1.43+/-0.17 and Gamma=0.9+/-0.4 (with N_H~2-7E+22 cm-2). The
0.3-10 keV flux of the source was ~0.8E-12 erg-1 cm-2 s-1. Pulsations were
found with P_pulse=15.757(1) s (MJD 56363.115) and an rms pulse fraction of
32.1(3)%. The observed X-ray luminosity during quiescent periods may be
explained by the neutron star being in supersonic propeller regimen.Comment: 9 pages, 7 figures, accepte
Perinatal asphyxia: CNS development and deficits with delayed onset
Perinatal asphyxia constitutes a prototype of obstetric complications occurring when pulmonary
oxygenation is delayed or interrupted. The primary insult relates to the duration of the period
lacking oxygenation, leading to death if not re-established. Re-oxygenation leads to a secondary
insult, related to a cascade of biochemical events required for restoring proper function. Perinatal
asphyxia interferes with neonatal development, resulting in long-term deficits associated to mental
and neurological diseases with delayed clinical onset, by mechanisms not yet clarified.
In the experimental scenario, the effects observed long after perinatal asphyxia have been explained
by over expression of sentinel proteins, such as poly(ADP-ribose) polymerase-1 (PARP-1),
competing for NAD+ during re-oxygenation, leading to the idea that sentinel protein inhibition
constitutes a suitable therapeutic strategy. Asphyxia induces transcriptional activation of proinflammatory
factors, in tandem with PARP-1 overactivation, and pharmacologically induced
PARP-1 inhibition also down-regulates the expression of proinflammatory cytokines.
Nicotinamide has been proposed as a suitable PARP-1 inhibitor. Its effect has been studied in
an experimental model of global hypoxia in rats. In that model, the insult is induced by immersing
rat foetuses into a water bath for various periods of time. Following asphyxia, the pups are
delivered, treated, and nursed by surrogate dams, pending further experiments. Nicotinamide
rapidly distributes into the brain following systemic administration, reaching steady state
concentrations sufficient to inhibit PARP-1 activity for several hours, preventing several of the
long-term consequences of perinatal asphyxia, supporting the idea that it constitutes a lead for
exploring compounds with similar or better pharmacological profiles
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