915 research outputs found
A New Sub-Period-Minimum Cataclysmic Variable With Partial Hydrogen Depletion And Evidence Of Spiral Disk Structure
We present time-resolved spectroscopy and photometry of CSS 120422:111127+571239 (=SBS 1108+574), a recently discovered SU UMa-type dwarf nova whose 55 minute orbital period is well below the cataclysmic variable (CV) period minimum of similar to 78 minutes. In contrast with most other known CVs, its spectrum features He I emission of comparable strength to the Balmer lines, implying a hydrogen abundance less than 0.1 of long-period CVs-but still at least 10 times higher than that in AM CVn stars. Together, the short orbital period and remarkable helium-to-hydrogen ratio suggest that mass transfer in CSS 120422 began near the end of the donor star's main-sequence lifetime, meaning that this CV is a strong candidate progenitor of an AM CVn system as described by Podsiadlowski et al. Moreover, a Doppler tomogram of the Ha line reveals two distinct regions of enhanced emission. While one is the result of the stream-disk impact, the other is probably attributable to spiral disk structure generated when material in the outer disk achieves a 2:1 orbital resonance with respect to the donor.NSF AST-1211196, AST-9987045Department of Physics at the University of Notre DameNSF Telescope System Instrumentation Program (TSIP)Ohio Board of RegentsOhio State University Office of ResearchAstronom
Magnetotunneling Between Two-dimensional Electron Gases in InAs-AlSb-GaSb Heterostructures
We have observed that the tunneling magnetoconductance between
two-dimensional (2D) electron gases formed at nominally identical InAs-AlSb
interfaces most often exhibits two sets of Shubnikov-de Haas oscillations with
almost the same frequency. This result is explained quantitatively with a model
of the conductance in which the 2D gases have different densities and can
tunnel between Landau levels with different quantum indices. When the epitaxial
growth conditions of the interfaces are optimized, the zero-bias
magnetoconductance shows a single set of oscillations, thus proving that the
asymmetry between the two electron gases can be eliminated.Comment: RevTeX format including 4 figures; submit for publicatio
Intraventricular Thrombi with Systemic Embolization: Two Clinical Cases
A formação de trombos intraventriculares é um complicação frequente nos doentes com miocardiopatia dilatada e enfarte agudo do miocárdio, sendo o risco de embolização sistémica muito variável em função da patologia subjacente e características subjacentes dos trombos. Os autores descrevem dois casos clínicos relativos a dois doentes internados no mesmo dia com trombos intraventriculares, volumosos, protuberantes e muito móveis, no contexto de miocardiopatia dilatada e enfarte agudo do miocárdio, que embolizaram para os membros inferiores. Salientam a importância da ecocardiografia no diagnóstico, caracterização morfológica inicial e controlo evolutivo dos trombos intraventriculares, aspectos fundamentais na avaliação do risco embólico. Na ausência de recomendações específicas quanto às opções terapêuticas – anticoagulação, trombólise ou remoção cirúrgica, os autores sublinham a necessidade de avaliação individualizada, «caso a caso», tendo em conta o risco embólico, hemorrágico, e cirúrgico
Weighing-in-motion wireless system for sustainable railway transport
Railway transport is well known as one of the safest and most energy-efficient transport modes, thus favoring its strengthening as part of a sustainable transport system. Yet, the track service life and the quality of the ride on a railway are dependent upon different factors, which can be assessed by a diverse set of technology based systems. In this context, this paper presents the EVO4Rail project that seeks to design, develop and implement a wireless monitoring system for weighing-in-motion and detecting faulty wheels in railway vehicles, positively impacting railway operation, maintenance and management, ultimately aiming at a sustainable rail transport.info:eu-repo/semantics/publishedVersio
Model for deriving benthic irradiance in the Great Barrier Reef from MODIS satellite imagery
We demonstrate a simple, spectrally resolved ocean color remote sensing model to estimate benthic photosynthetically active radiation (bPAR) for the waters of the Great Barrier Reef (GBR), Australia. For coastal marine environments and coral reefs, the underwater light field is critical to ecosystem health, but data on bPAR rarely exist at ecologically relevant spatio-temporal scales. The bPAR model presented here is based on Lambert-Beer’s Law and uses: (i) sea surface values of the downwelling solar irradiance, Es(λ); (ii) high-resolution seafloor bathymetry data; and (iii) spectral estimates of the diffuse attenuation coefficient, Kd(λ), calculated from GBR-specific spectral inherent optical properties (IOPs). We first derive estimates of instantaneous bPAR. Assuming clear skies, these instantaneous values were then used to obtain daily integrated benthic PAR values. Matchup comparisons between concurrent satellite-derived bPAR and in situ values recorded at four optically varying test sites indicated strong agreement, small bias, and low mean absolute error. Overall, the matchup results suggest that our benthic irradiance model was robust to spatial variation in optical properties, typical of complex shallow coastal waters such as the GBR. We demonstrated the bPAR model for a small test region in the central GBR, with the results revealing strong patterns of temporal variability. The model will provide baseline datasets to assess changes in bPAR and its external drivers and may form the basis for a future GBR water-quality index. This model may also be applicable to other coastal waters for which spectral IOP and high-resolution bathymetry data exist
Concomitant pulmonary embolism and aortic dissection: approach to anticoagulation
Os autores descrevem um caso de uma doente admitida após episódio pré-sincopal
associado a precordialgia e cujo ecocardiograma sumário feito no Servic¸o de Urgência demonstrou alterac¸ões compatíveis com tromboembolismo pulmonar, tendo a doente sido submetida
a terapêutica fibrinolítica, após episódio de paragem cardiorrespiratória. Na angiotomografia
de tórax feita posteriormente para confirmac¸ão diagnóstica demonstra-se a presenc¸a não só de
trombos no nível da artéria pulmonar, mas também de dissec¸ão da aorta Stanford B, tendo-se
optado pela manutenc¸ão de anticoagulac¸ão terapêutica e a doente evoluído de forma favorável.The authors describe a case of a patient admitted with a pre-syncopal episode and precordial discomfort, and whose cardiac ultrasound performed in the Emergency Room was suggestive of Pulmonary Embolism. The patient was submitted to fibrinolytic therapy after cardiac arrest. The computerized tomography done after this episode not only confirmed the presence of pulmonary embolism but had also shown a Stanford Type B Aortic Dissection. The option was to maintain the therapeutic anticoagulation, having the patient evolved favourably.info:eu-repo/semantics/publishedVersio
The relationship between dry eye and sleep quality
Purpose: Sleep is an important determinant of health and quality of life. This study aimed to clarify the association between dry eye and sleep quality using a large population-based cohort. Methods: 71,761 participants (19-94 yrs, 59.4% female) from the Lifelines cohort in the Netherlands were assessed for dry eye using the Women's Health Study Dry Eye Questionnaire. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI). Logistic regression was used to examine the relationship between poor sleep quality (PSQI score > 5) and dry eye, while correcting for age, sex, BMI, education, income, and 51 possible confounding comorbidities, including autoimmune diseases and psychiatric disorders. Results: Overall, 8.9% of participants had dry eye. Of these, 36.4% had poor sleep quality compared to 24.8% of controls (OR 1.52 (95%CI 1.44-1.60), P < 0.0001, corrected for age and sex). After correcting for all comorbidities, dry eye was still associated with poor sleep (OR 1.20 (95%CI 1.11-1.28), P < 0.0001). This relationship was seen across all ages and sexes. Patients with dry eye scored worse on all subcomponents of the PSQI. Almost one-in-two (44.9%) persons with dry eye symptoms "often" or "constantly" had poor sleep quality. This proportion was similar to participants with sleep apnea and osteoarthritis. Additionally, increasing symptom frequency was tied to increased prevalence of poor sleep quality. Conclusions: All components of sleep quality were significantly reduced in participants with dry eye, even after correcting for comorbidities. These results indicate the substantial impact of dry eye on patients' lives, especially for those with frequent symptoms
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