2,279 research outputs found
Correlating the interstellar magnetic field with protostellar jets and its sources
This article combines new CCD polarimetric data with previous information
about protostellar objects in a search for correlations involving the
interstellar magnetic field. Specifically, we carried out an optical
polarimetric study of a sample of 28 fields of 10 X 10 arcmin^2 located in the
neighborhood of protostellar jets and randomly spread over the Galaxy. The
polarimetry of a large number of field stars is used to estimate both the
average and dispersion of the interstellar magnetic field (ISMF) direction in
each region. The results of the applied statistical tests are as follows.
Concerning the alignment between the jet direction and the interstellar
magnetic field, the whole sample does not show alignment. There is, however, a
statistically significant alignment for objects of Classes 0 and I. Regarding
the interstellar magnetic field dispersion, our sample presents values slightly
larger for regions containing T Tauri objects than for those harboring younger
protostars. Moreover the ISMF dispersion in regions containing high-mass
objects tends to be larger than in those including only low-mass protostars. In
our sample, the mean interstellar polarization as a function of the average
interstellar extinction in a region reaches a maximum value around 3% for A(V)
= 5, after which it decreases. Our data also show a clear correlation of the
mean value of the interstellar polarization with the dispersion of the
interstellar magnetic field: the larger the dispersion, the smaller the
polarization. Based on a comparison of our and previous results, we suggest
that the dispersion in regions forming stars is larger than in quiescent
regions.Comment: ApJ accepte
Noninvasive mechanical ventilation may be useful in treating patients who fail weaning from invasive mechanical ventilation: a randomized clinical trial
Results Of 65 patients who failed T-piece trials, 28 were placed on NPPV and 37 were placed on IMV. The ages of patients in the NPPV and IMV groups were 67.6 ± 15.5 and 59.7 ± 17.6 years, respectively. Heart disease, post-surgery respiratory failure, and chronic pulmonary disease aggravation were the most frequent causes of IMV use. In both groups, ventilation time before T-piece trial was 7.3 ± 4.1 days. Heart and respiratory parameters were similar for the two groups at 1 and 30 minutes of T-piece trial. The percentage of complications in the NPPV group was lower (28.6% versus 75.7%), with lower incidences of pneumonia and tracheotomy. Length of stay in the intensive care unit and mortality were not statistically different when comparing the groups. Conclusion The results suggest that NPPV is a good alternative for ventilation of patients who fail initial weaning attempts. NPPV reduces the incidence of pneumonia associated with mechanical ventilation and the need for tracheotomy
Fractional Landau-Lifshitz-Gilbert equation
The dynamics of a magnetic moment or spin are of high interest to applications in technology. Dissipation in these systems is therefore of importance for improvement of efficiency of devices, such as the ones proposed in spintronics. A large spin in a magnetic field is widely assumed to be described by the Landau-Lifshitz-Gilbert (LLG) equation, which includes a phenomenological Gilbert damping. Here, we couple a large spin to a bath and derive a generic (non-)Ohmic damping term for the low-frequency range using a Caldeira-Leggett model. This leads to a fractional LLG equation, where the first-order derivative Gilbert damping is replaced by a fractional derivative of order sϵR≥0. We show that the parameter s can be determined from a ferromagnetic resonance experiment, where the resonance frequency and linewidth no longer scale linearly with the effective field strength
Pinto Beans (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e L.) as a Functional Food: Implications on Human Health
Most foods are considered functional in terms of providing nutrients and energy to sustain daily life, but dietary systems that are capable of preventing or remediating a stressed or diseased state are classified as functional foods. Dry beans (Phaseolus vulgaris L.) contain high levels of chemically diverse components (phenols, resistance starch, vitamins, fructooligosaccharides) that have shown to protect against such conditions as oxidative stress, cardiovascular disease, diabetes, metabolic syndrome, and many types of cancer, thereby positioning this legume as an excellent functional food. Moreover, the United States has a rich dry bean history and is currently a top producer of dry beans in the world with pinto beans accounting for the vast majority. Despite these attributes, dry bean consumption in the US remains relatively low. Therefore, the objective of this manuscript is to review dry beans as an important US agricultural crop and as functional food for the present age with an emphasis on pinto beans
On the regular-geometric-figure solution to the N-body problem
The regular-geometric-figure solution to the -body problem is presented in
a very simple way. The Newtonian formalism is used without resorting to a more
involved rotating coordinate system. Those configurations occur for other kinds
of interactions beyond the gravitational ones for some special values of the
parameters of the forces. For the harmonic oscillator, in particular, it is
shown that the -body problem is reduced to one-body problems.Comment: To appear in Eur. J. Phys. (5 pages
Preparation and Electrochemical Characterization of a Carbon Ceramic Electrode Modified with Ferrocenecarboxylic Acid
The present paper describes the characterization of a carbon ceramic electrode modified with ferrocenecarboxylic acid (designated as CCE/Fc) by electrochemical techniques and its detection ability for dopamine. From cyclic voltammetric experiments, it was observed that the CCE/Fc presented a redox pair at Epa = 405 mV and Epc = 335 mV (ΔE = 70 mV), related to the ferrocene/ferrocenium process. Studies showed a considerably increase in the redox currents at the same oxidation potential of ferrocene (Epa = 414 mV vs. Ag/AgCl) in the presence of dopamine (DA), differently from those observed when using only the unmodified CCE, in which the anodic peak increase was considerably lower. From SWV experiments, it was observed that the AA (ascorbic acid) oxidation at CCE/Fc occurred in a different potential than the DA oxidation (with a peak separation of approximately 200 mV). Moreover, CCE/Fc did not respond to different AA concentrations, indicating that it is possible to determine DA without the AA interference with this electrode
Statistical Analysis of the Droplet Size Distribution of Tire Pyrolysis Oil-Diesel Oil Sprays
The liquid product obtained from tire pyrolysis process, called tire pyrolysis oil (TPO), has a great attraction as an alternative fuel, as it has a viscosity of 5.43 cSt (Sharma et al., 2016), density of 921 kg/mÂł (Gamboa et al., 2020), surface tension of 0.028 N/m (Chumpitaz et al., 2019), and higher heating value of 46.32 MJ/kg (Das et al., 2017), which are similar to diesel oil. These physical and chemical properties have motivated research into its application in furnaces, boilers and compression ignition engines. Generally, TPO is blended with diesel or biodiesel in order to decrease the percentage of sulfur and improve the cetane number of the fuel blend (Sharma et al., 2016). However, the evaluation of the quality and applicability of TPO has been focused mainly on combustion emissions and the performance of thermal equipment fueled with this fuel (and diesel/biodiesel blends), where the atomization process has been ignored, which is closely linked with the efficiency of liquid fuel evaporation and combustion. Thus, in this work, an evaluation of the atomization quality of blends of tire pyrolysis oil and diesel oil was carried out based on the comparison of the uniformity parameters of the drop size distribution of fuel sprays. The distribution function used was the Log-Normal function, as it allowed reconstructing the droplet size distribution of the sprays with only the mass median diameter and Sauter mean diameter. These values were measured using the Malvern Spraytec laser diffraction system model STP5936 (Chumpitaz et al., 2019). The fuel sprays were generated with a twin-fluid atomizer (type Y-jet) operating at air-to-fuel mass ratio (RAL) in the range of 0.05 to 0.35. The results showed that the higher the percentage by mass of TPO in the fuel blend, the lower the uniformity of the spray. Furthermore, a uniform TPO-DO spray with smaller mean diameters (0.15) are applied and percentages of TPO in the blend less than 5% are used
Remote Sensing analysis of the meanders migration in the Mamorecillo River between 1985 and 2012, Bolivia
The morphology of a channel, in a space-time resolution, suffers with sedimentological processes of erosion, transport and deposition. Processes that are more accentuated in meandering channels. In the present work the objective is to analyze, identify and discuss the changes occurred in spatial and temporal sequence in the form of the meanders and river bed of a section of the Mamorecillo River between the provinces of Cochabamba and Santa Cruz - Bolivia. Characterized by being an extensively meandering river - characteristic of the river basin in which it is inserted, the Amazon Basin, the present study, through remote sensing resources, seeks to discuss and correlate the changes occurred in the channel in a period of twenty-seven years (1985-2012). As well as understanding the processes of migration of the meanders that this section of the Mamorecillo River suffered through the sedimentological processes of erosion and deposition and consequently understand the processes in the Amazon basin. For the accomplishment of the work, the studied area was delimited and allied with geoprocessing tools such as software and aerial images, the main geomorphological features were identified and their changes discussed during the studied period. In this work, we intend to correlate and verify the inter-dependence (referring to the sedimentological and / or hydrological contribution) that exists between the Mamorecillo River and the Chimoreacute; and Ichilo rivers
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