694 research outputs found
Inward Motions of the Compact SiO Masers Around VX Sagittarii
We report Very Long Baseline Array (VLBA) observations of 43 GHz v=1, J=1-0
SiO masers in the circumstellar envelope of the M-type semi-regular variable
star VX Sgr at 3 epochs during 1999 April-May. These high-resolution VLBA
images reveal a persistent ringlike distribution of SiO masers with a projected
radius of ~3 stellar radii. The typical angular size of 0.5 mas for individual
maser feature was estimated from two-point correlation function analysis for
maser spots. We found that the apparent size scale of maser features was
distinctly smaller than that observed in the previous observations by comparing
their fractions of total power imaged. This change in the size scale of maser
emission may be related to stellar activity that caused a large SiO flare
during our observations. Our observations confirmed the asymmetric distribution
of maser emission, but the overall morphology has changed significantly with
the majority of masers clustering to the north-east of the star compared to
that lying to the south-west direction in 1992. By identifying 42 matched maser
features appearing in all the three epochs, we determined the contraction of an
SiO maser shell toward VX Sgr at a proper motion of -0.507 mas/yr,
corresponding to a velocity of about 4 km/s at a distance of 1.7 kpc to VX Sgr.
Such a velocity is on the order of the sound speed, and can be easily explained
by the gravitational infall of material from the circumstellar dust shell.Comment: 26 pages, 5 figures, 4 tables, accepted for publication in Ap
Relative astrometry of the J=1-0, v=1 and v=2 SiO masers towards R Leonis Minoris using VERA
Oxygen-rich Asymptotic Giant Branch (AGB) stars are intense emitters of SiO
and HO maser lines at 43 (J=1-0, v=1 and 2) and 22 GHz, respectively. VLBI
observations of the maser emission provides a unique tool to sample the
innermost layers of the circumstellar envelopes in AGB stars. Nevertheless, the
difficulties in achieving astrometrically aligned v=1 and v=2 SiO maser maps
have traditionally prevented a unique interpretation of the observations in
terms of physical underlying conditions, which depend on the nature of the SiO
pumping mechanism.
We have carried out observations of the SiO and HO maser emission towards
RLMi, using the astrometric capabilities of VERA. Due to the too-weak emission
of the reference calibrator we had to develop a special method to accurately
relate the coordinates for both transitions. We present relative
astrometrically aligned v=1 and v=2 J=1-0 SiO maser maps, at multiple epochs,
and discuss the astrophysical results. The incorporation of astrometric
information into the maps of SiO masers challenges the weak points in the
current theoretical models, which will need further refinements to address the
observations results.Comment: 17 pages, 8 figure
Alpha-methylnorepinephrine, a selective alpha2-adrenergic agonist for cardiac resuscitation
AbstractOBJECTIVESThe purpose of this study was to investigate the effects of a selective alpha2-adrenergic agonist, alpha-methylnorepinephrine (alphaMNE) as an alternative vasopressor agent during cardiopulmonary resuscitation (CPR).BACKGROUNDFor more than 40 years, epinephrine has been the vasopressor agent of choice for CPR. Its beta- and alpha1-adrenergic effects increase myocardial oxygen consumption, magnify global myocardial ischemia and increase the severity of postresuscitation myocardial dysfunction.METHODSVentricular fibrillation (VF) was induced in 20 Sprague-Dawley rats. After 8 min of untreated VF, mechanical ventilation and precordial compression began. AlphaMNE, epinephrine or saline placebo was injected into the right atrium 2 min after the start of precordial compression. As an additional control, one group of animals was pretreated with alpha2-receptor blocker, yohimbine, before injection of alphaMNE. Defibrillation was attempted 4 min later. Left ventricular pressure, dP/dt40, negative dP/dt and cardiac index were measured for an interval of 240 min after resuscitation.RESULTSExcept for saline placebo and yohimbine-treated animals, comparable increases in coronary perfusion pressure were observed after each drug intervention. All animals were successfully resuscitated. Left ventricular diastolic pressure, cardiac index, dP/dt40and negative dP/dt were more optimal after alphaMNE; this was associated with significantly better postresuscitation survival. Pretreatment with yohimbine abolished the beneficial effects of alphaMNE.CONCLUSIONSThe selective alpha2-adrenergic agonist, alphaMNE, was as effective as epinephrine for initial cardiac resuscitation but provided strikingly better postresuscitation myocardial function and survival
Mejoramiento de la calidad de vida de las niñas, niños y adolescente en estado de vulnerabilidad en la provincia de Ilo - Moquegua a través de la creación de un albergue infantil y adolescente con un centro técnico productivo
Esta investigación se realizó con el fin de mejorar la “calidad de vida” de las niñas, niños y
adolescentes en estado vulnerable desde que llegan al albergue hasta su reinserción a la
sociedad. Todo esto será posible gracias a la creación de un Albergue donde podrán vivir en
un ambiente familiar y un Centro Técnico Productivo dedicado a la su formación Técnica y
que cumple con los requerimientos básicos para su funcionamiento bajo los estándares y
normativas que cada entidad encargada regula. Se evalúa la problemática social y la existencia
de espacios que brinden el servicio Educativo Técnico y de albergue.
El proyecto se encuentra ubicado en la provincia de Ilo, Moquegua.
Es importante ver la Arquitectura desde el lado humano, para poder contribuir a la mejora de
nuestra especie mediante espacios creados con las condiciones aptas para realizar actividades
y que no solo sean un espacio encerrado para cumplir alguna función intrascendente.Tesi
Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1, 6-heptadiene-3,5-dione) Blocks the Chemotaxis of Neutrophils by Inhibiting Signal Transduction through IL-8 Receptors
We investigated the impact of curcumin on neutrophils. Chemotactic activity via human recombinant IL-8 (hrIL-8) was significantly inhibited by curcumin. Curcumin reduced calcium ion flow induced by internalization of the IL-8 receptor. We analyzed flow cytometry to evaluate the status of the IL-8 receptor after curcumin treatment. The change in the distribution of receptors intracellularly and on the cell surface suggested that curcumin may affect the receptor trafficking pathway intracellulary.
Rab11 is a low molecular weight G protein associated with the CXCR recycling pathway. Following curcumin treatment, immunoprecipitation studies showed that the IL-8 receptor was associated with larger amounts of active Rab11 than that in control cells. These data suggest that curcumin induces the stacking of the Rab11 vesicle complex with CXCR1 and CXCR2 in the endocytic pathway. The mechanism for antiinflammatory response by curcumin may involve unique regulation of the Rab11 trafficking molecule in recycling of IL-8 receptors
OmniLRS: A Photorealistic Simulator for Lunar Robotics
Developing algorithms for extra-terrestrial robotic exploration has always
been challenging. Along with the complexity associated with these environments,
one of the main issues remains the evaluation of said algorithms. With the
regained interest in lunar exploration, there is also a demand for quality
simulators that will enable the development of lunar robots. % In this paper,
we explain how we built a Lunar simulator based on Isaac Sim, Nvidia's robotic
simulator. In this paper, we propose Omniverse Lunar Robotic-Sim (OmniLRS) that
is a photorealistic Lunar simulator based on Nvidia's robotic simulator. This
simulation provides fast procedural environment generation, multi-robot
capabilities, along with synthetic data pipeline for machine-learning
applications. It comes with ROS1 and ROS2 bindings to control not only the
robots, but also the environments. This work also performs sim-to-real rock
instance segmentation to show the effectiveness of our simulator for
image-based perception. Trained on our synthetic data, a yolov8 model achieves
performance close to a model trained on real-world data, with 5% performance
gap. When finetuned with real data, the model achieves 14% higher average
precision than the model trained on real-world data, demonstrating our
simulator's photorealism.% to realize sim-to-real. The code is fully
open-source, accessible here: https://github.com/AntoineRichard/LunarSim, and
comes with demonstrations.Comment: 7 pages, 4 figure
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