269 research outputs found
X-ray flares on the UV Ceti-type star CC Eridani: a "peculiar" time-evolution of spectral parameters
Context: Weak flares are supposed to be an important heating agent of the
outer layers of stellar atmospheres. However, due to instrumental limitations,
only large X-ray flares have been studied in detail until now.
Aims: We used an XMM-Newton observation of the very active BY-Dra type binary
star CC Eri in order to investigate the properties of two flares that are
weaker than those typically studied in the literature.
Methods: We performed time-resolved spectroscopy of the data taken with the
EPIC-PN CCD camera. A multi-temperature model was used to fit the spectra. We
inferred the size of the flaring loops using the density-temperature diagram.
The loop scaling laws were applied for deriving physical parameters of the
flaring plasma. We also estimated the number of loops involved in the observed
flares.
Results: A large X-ray variability was found. Spectral analysis showed that
all the regions in the light curve, including the flare segments, are
well-described by a 3-T model with variable emission measures but,
surprisingly, with constant temperatures (values of 3, 10 and 22 MK). The
analysed flares lasted ~ 3.4 and 7.1 ks, with flux increases of factors
1.5-1.9. They occurred in arcades made of a few tens of similar coronal loops.
The size of the flaring loops is much smaller than the distance between the
stellar surfaces in the binary system, and even smaller than the radius of each
of the stars. The obtained results are consistent with the following ideas: (i)
the whole X-ray light curve of CC Eri could be the result of a superposition of
multiple low-energy flares, and (ii) stellar flares can be scaled-up versions
of solar flares.Comment: 14 pages, 12 figures. Accepted for publication in Astronomy &
Astrophysic
Carcinoma bronquiolo-alveolar en perro : un caso clínico. Diagnóstico y tratamiento quirúrgico
Se describe un caso clínico de un perro Staffordshire Bull Terrier macho de 2 años de edad que presentaba un historial de insuficiencia respiratoria. Tras la exploración física, se aprecia la existencia de un derrame pleural procediéndo-se a realizar diferentes pruebas diagnósticas para establecer su causa incluyendo la toracocentesis y cultivo bacteriológico, radiología y ecografía torácica. Se describe la vía de abordaje quirúrgico uti- lizada en este caso (esternotomía mediana); así como, la intervención de lobectomía a la que fue sometido el paciente. La pieza de extirpación quirúrgica fue remitida para su análisis histopatolóqico, confirmando el diagnóstico de carcinoma bronquiolo-alveolar primario de pulmón.A clinical case is described of a two year oid male Staffordshire Bull Terrier who was sent with a history of respiratory insufficiency. After a physical examination a pleural effusion was found preceeding various diagnostics such as thoracocentesis, bacteriological culture, thoracic radiographs and an ultrasound were issued to establish the cause. The surgical approach (medium esternotomy) and the lobectomy the patient suffered from are described. The surgical sample was sent to be analised histopatholoqícally, confirming the pulmonary primary bronchiolar-alvcolar carcinoma diagnostic
Dificultades en la Accesibilidad Web de las Universidades Españolas de acuerdo a la Norma WCAG 2.0
The purpose of the study has been to learn of possible limitations in the level of accessibility of 74 Spanish universities’ web sites. The tool, TAW, was used to detect the existing barriers in each web, based on the WCAG 2.0 regulation. After an automatic and manual review of the principles, guidelines and criteria of priority levels A and AA, a percentage analysis showed that none of the universities surpassed these aspects entirely for either of the two web pages analysed, although the university with the best accessibility on both web pages was the University of Granada, followed by the University of Alicante. The study concludes by recommending revisions and adjustments to resolve these problems and to facilitate web accessibility.El propósito del estudio ha sido conocer posibles limitaciones en el nivel de accesibilidad de las páginas principales y de estudiantes, de los sitios web de 74 Universidades españolas, para lo cual se ha utilizado la herramienta TAW, que permite analizar, de acuerdo a la norma WCAG 2.0, la existencia de barreras en ellas. Después de revisar automática y manualmente los Principios, Pautas y Criterios de conformidad de la norma, en sus niveles de prioridad A y AA, un análisis porcentual constata que ni una sola de las universidades los supera en su totalidad en ninguna de las dos páginas analizadas, aunque la mejor situada en accesibilidad es la de Granada en ambas páginas, seguida de la de Alicante. Se concluye recomendando hacer chequeos y ajustes para resolver estos problemas y facilitar la accesibilidad web
Relationship between the gingival biotype and the results of root covering surgical procedures : a systematic review
Tissue biotypes are related to the results of periodontal therapy, conventional prosthodontics, implant therapy and root covering procedures. We conducted a systematic review (SR) of the literature about the relationship between the gingival biotype and
Job qualification and satisfaction: a study about employment which we have been previously trained for
Esta investigación, que ha contado con 80 sujetos, explora la relación entre las diferentes dimensiones de la satisfacción laboral y la cualificación del trabajo (relacionado o no con los currículos académicos previos). Se ha realizado utilizando Cuestionario de Satisfacción Laboral S20/23. Los resultados han sido significativos, confirmándose la hipótesis: hemos encontrado mayor satisfacción laboral en los sujetos que desarrollan trabajos cualificados y menor satisfacción en los que desarrollan trabajos no cualificados.This research study, which had 80 subjects, explores the relationship between different dimensions of job satisfaction and job qualification (related or not to prior academic curriculum). The study was carried out using Job Satisfaction Questionnaire S20/23. The results were significant, confirming the hypothesis: we found greater job satisfaction in subjects who carry out skilled jobs and lower satisfaction in those who carry out unskilled jobs.Psicología Socia
Deep XMM-Newton observation of the Eta Chamaleontis cluster
The members of the Eta Chamaleontis cluster are in an evolutionary stage in
which disks are rapidly evolving. It also presents some peculiarities, such as
the large fraction of binaries and accretion disks, probably related with the
cluster formation process. Its proximity makes this stellar group an ideal
target for studying the relation between X-ray emission and those stellar
parameters. The main objective of this work is to determine general X-ray
properties of the cluster members in terms of coronal temperature, column
density, emission measure, X-ray luminosity and variability. We also aim to
establish the relation between the X-ray luminosity of these stars and other
stellar parameters, such as binarity and presence of accretion disks. A study
of flare energies for each flare event and their relation with some stellar
parameters is also performed. We used proprietary data from a deep XMM-Newton
observation pointed at the core of the Eta Chamaleontis cluster. Specific
software for the reduction of XMM-Newton data was used for the analysis of our
observation. For the detection of sources, we used the wavelet-based code
PWDetect. General coronal properties were derived from plasma model fitting. We
also determined variability of the Eta Chamaleontis members in the EPIC
field-of-view. A total of six flare-like events were clearly detected in five
different stars. For them, we derived coronal properties during the flare
events and pseudo-quiescent state separately. In our observations, stars that
underwent a flare event have higher X-ray luminosities in the pseudo-quiescent
state than cluster members with similar spectral type with no indications of
flaring, independently whether they have an accretion disk or not. Observed
flare energies are typical of both pre-main and main-sequence M stars. We
detected no difference between flare energies of stars with and without an
accretion disk.Comment: Accepted for publication in Astronomy and Astrophysics. 12 pages, 30
individual figure
Dificultades en la Accesibilidad Web de las Universidades Españolas de acuerdo a la Norma WCAG 2.0
The 8-Odorant Barcelona Olfactory Test (BOT-8): Validation of a New Test in the Spanish Population During the COVID-19 Pandemic
COVID-19; Pèrdua d'olfacte; Prova de l'olfacteCOVID-19; Loss of smell; Smell testCOVID-19; Pérdida de olfato; Prueba del olfatoBackground and objective: Most smell tests are difficult to implement in daily clinical practice owing to their long duration. The aim of the present study was to develop and validate a short, easy-to-perform, and reusable smell test to be implemented during the COVID-19 pandemic.
Methods: The study population comprised 120 healthy adults and 195 patients with self-reported olfactory dysfunction (OD). The 8-Odorant Barcelona Olfactory Test (BOT-8) was used for detection, memory/recognition, and forced-choice identification. In addition, a rose threshold test was performed, and a visual analog scale was applied. The Smell Diskettes Olfaction Test (SDOT) was used for correlation in healthy volunteers, and the University of Pennsylvania Smell Identification Test (UPSIT) was used for patients with OD to establish cut-offs for anosmia and hyposmia. In order to take account of the COVID-19 pandemic, disposable cotton swabs with odorants were compared with the original test.
Results: In healthy persons, the mean (SD) BOT-8 score was 100% for detection, 94.5% (1.07) for memory/recognition, and 89.6% (0.86) for identification. In patients with OD, the equivalent values were 86% (32.8), 73.2% (37.9), and 77.1% (34.2), respectively. BOT-8 demonstrated good test-retest reliability, with agreement of 96.7% and a quadratic k of 0.84 (P<.001). A strong correlation was observed between BOT-8 and SDOT (r=0.67, P<.001) and UPSIT (r=0.86, P<.001). Agreement was excellent for disposable cotton swabs, with a k of 0.79 compared with the original test. The cut-off point for anosmia was ≤3 (area under the curve, 0.83; sensitivity, 0.673; specificity, 0.993).
Conclusion: BOT-8 offers an efficient and fast method for assessment of smell threshold, detection, memory, and identification in daily clinical practice. Disposable cotton swabs with odorants proved to be useful and safe during the COVID-19 pandemic
Criteria for spectral classification of cool stars using high-resolution spectra
We have compiled a large number of optical spectra of cool stars taken with different high-resolution echelle spectrographs (R ≃ 40 000). Many of those are available as spectral libraries (Montes et al. 1997, 1998, 1999,
Producción y descomposición de hojarasca en el bosque natural de Cayo Quemado, Livingston, Izabal, Guatemala
Los bosques naturales de los sistemas marino costeros son importantes por los bienes y servicios ambientales que prestan. Sin embargo, en la Costa Atlántica del país son vulnerables a múltiples amenazas. Como parte de un inventario de carbono del bosque natural Cayo Quemado, se cuantificó la producción y descomposición de hojarasca de las especies vegetales predominantes por unidad de área: Mangle rojo (Rhizophora mangle) 38.14%, zapotón (Pachira aquatica) 19.07%, cahue (Pterocarpus officinalis) 18.56% y anonillo (Rollinia pittieri) 7.22%. En bloques de 30 x 30 m, fueron colocadas en forma aleatoria trampas de 2 x 2 m, y bolsas de descomposición con 200 g de hojarasca fresca, con tres repeticiones, con lecturas cada 30 días. Se concluye que el mangle rojo aportó 0.6015, el zapotón 0.2701, el cahué 0.1836 y el anonillo 0.1119 para un total de 1.1671 MgC/ha, equivalentes a 4.28 MgCO2/ha. Así mismo, se determinó que después de cinco meses de descomposición la masa seca remanente fue de cahué (47.9%), zapotón (40.94%), mangle (38.86%) y anonillo (30.41%) en base a peso seco. El rol de las especies vegetales asociadas a los manglares es de suma importancia por su naturaleza recalcitrante y preservación del Cayo Quemado per se
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