1,136 research outputs found
Kinematic study of planetary nebulae in NGC 6822
By measuring precise radial velocities of planetary nebulae (which belong to
the intermediate age population), H II regions, and A-type supergiant stars
(which are members of the young population) in NGC 6822, we aim to determine if
both types of population share the kinematics of the disk of H I found in this
galaxy.
Spectroscopic data for four planetary nebulae were obtained with the high
spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the
Magellan telescope at Las Campanas Observatory. Data for other three PNe and
one H II region were obtained from the SPM Catalog of Extragalactic Planetary
Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m
telescope at the Observatorio Astron\'omico Nacional, M\'exico. In the
wavelength calibrated spectra, the heliocentric radial velocities were measured
with a precision better than 5-6 km s. Data for three additional H II
regions and a couple of A-type supergiant stars were collected from the
literature. The heliocentric radial velocities of the different objects were
compared to the velocities of the H i disk at the same position.
From the analysis of radial velocities it is found that H II regions and
A-type supergiants do share the kinematics of the H I disk at the same
position, as expected for these young objects. On the contrary, planetary
nebula velocities differ significantly from that of the H I at the same
position. The kinematics of planetary nebulae is independent from the young
population kinematics and it is closer to the behavior shown by carbon stars,
which are intermediate-age members of the stellar spheroid existing in this
galaxy. Our results are confirming that there are at least two very different
kinematical systems in NGC 6822
Combined therapies of antithrombotics and antioxidants delay in silico brain tumor progression
Glioblastoma multiforme, the most frequent type of primary brain tumor, is a
rapidly evolving and spatially heterogeneous high-grade astrocytoma that
presents areas of necrosis, hypercellularity and microvascular hyperplasia. The
aberrant vasculature leads to hypoxic areas and results in an increase of the
oxidative stress selecting for more invasive tumor cell phenotypes. In our
study we assay in silico different therapeutic approaches which combine
antithrombotics, antioxidants and standard radiotherapy. To do so, we have
developed a biocomputational model of glioblastoma multiforme that incorporates
the spatio-temporal interplay among two glioma cell phenotypes corresponding to
oxygenated and hypoxic cells, a necrotic core and the local vasculature whose
response evolves with tumor progression. Our numerical simulations predict that
suitable combinations of antithrombotics and antioxidants may diminish, in a
synergetic way, oxidative stress and the subsequent hypoxic response. This
novel therapeutical strategy, with potentially low or no toxicity, might reduce
tumor invasion and further sensitize glioblastoma multiforme to conventional
radiotherapy or other cytotoxic agents, hopefully increasing median patient
overall survival time.Comment: 8 figure
Pure hydrogen from biogas: Intensified methane dry reforming in a two-zone fluidized bed reactor using permselective membranes
Methane dry reforming of biogas can be a sustainable source of hydrogen but the development of this technology is hindered by limitations such as endothermicity and catalyst deactivation by coke. A two zone fluidized bed reactor coupling permselective Pd/Ag membranes counteracts them and allows to intensify the process obtaining a stable pure hydrogen production. Here we report the effect of operation variables (i.e., temperature, total bed height, nature and partial pressure of regenerative agent, relative height of the regeneration and reaction zones, and use of an activation period) on the yield to hydrogen and stability of the process. Hydrogen over-yields, compared with the conventional fluidized bed reactor, in the range of +200% to +100% were obtained for the entire interval of temperatures 475–575 °C whilst maintaining stable operation by continuous catalyst regeneration. Around 70% of it was pure hydrogen coming from the permeate side of the membranes. The proposed reactor configuration greatly increases both methane conversion and selectivity to hydrogen (expressed as H 2 /CO ratio), not only in relation to our own conventional reactor findings but also regarding other published results
Health-related quality of life among smoking relapsers
Background: Previous studies have shown that smoking is associated with health-related quality of life (HRQoL) impairment. In order to evaluate HRQoL in a sample of Spanish relapsers, a cross-sectional study was conducted. Method: The sample was made up of 775 smokers who had relapsed after a period of abstinence. HRQoL was evaluated using the Euro-Qol questionnaire (EQ-5D); through the descriptive profile, the EQ-5D index and the visual analogue scale (EQ-VAS). Results: Higher nicotine dependence was related to worse HRQL. According to the EQ-VAS, higher daily cigarette consumption and more years smoking were related to worse perceived health. In the EQ-5D those who had quit smoking in the previous year perceived worse health. Mobility and anxiety/ depression are the dimensions affected by smoking. Those who are more nicotine dependent (OR = 2.29) and have been smoking for longer (OR = 4.12) are more likely to have mobility problems; and those who are nicotine dependent (OR = 1.85) and relapsed more than a year ago (OR = 0.63), are more likely to experience anxiety/ depression. Conclusions: Nicotine dependence demonstrated a determining effect on HRQOL deterioration in smokers who have relapsed
Efecto de la música sobre la ansiedad y el dolor en pacientes con ventilación mecánica
La capacidad de la música para aliviar la ansiedad o el dolor ha sido utilizada ampliamente a lo largo de la historia. Objetivo: Examinar los efectos de la música sobre la ansiedad y el dolor en pacientes con ventilación mecánica invasiva. Diseño: Un ensayo aleatorizado controlado con medidas repetidas. Material y método: estudio prospectivo experimental con distribución aleatoria, en un hospital universitario de tercer nivel, de enero de 2009 a junio de 2010. La muestra fue de 44 participantes. La intervención consistió en una sesión musical de 30 min, con auriculares, en habitación individual. Al grupo control se le mantuvo sin ningún cambio en el entorno habitual de una unidad de cuidados intensivos. A cada paciente se le realizaron un mÃnimo de 3 y un máximo de 5 sesiones musicales. La música fue escogida por el paciente entre una selección musical preparada por el equipo investigador. La ansiedad, el dolor y las variables hemodinámicas frecuencia cardiaca, frecuencia respiratoria, tensión arterial sistólica y diastólica se midieron en el momento basal, tras la sesión musical y una hora después de la audición musical. Resultados: La musicoterapia disminuyó significativamente la ansiedad (p = 0,000), medida con la escala de Ansiedad Estado-Rasgo (STAI). No hubo diferencia significativa en los niveles de dolor (p = 0,157), medida con la escala visual analógica. No se demostró efecto sumativo a lo largo de las múltiples sesiones. Conclusión: La música reduce la ansiedad en los pacientes con ventilación mecánica invasiva, pudiéndose establecer como una herramienta no farmacológica a añadir a las opciones terapéuticas de las cuales disponemos
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