Influencia del ángulo de incidencia en el retemblado en procesos de torneado

El presente trabajo estudia el fenómeno del retemblado en un proceso de corte de metal. El efecto del roce entre la herramienta de corte y el material de trabajo es parcialmente explicado utilizando un modelo matemático. La influencia del ángulo de incidencia de la herramienta en el proceso de corte de metal es analizada experimentalmente a través de diagramas de estabilidad

A new Luminous Variable in M33

We present a new luminous star in M33 located in the nuclear region. The star shows strong FeII and [FeII] forest, hydrogen emissions in the spectrum, as well as nebular lines. TiII and SiII lines were detected in absorption, their radial velocity shifted by ~ -30km/s relative to emission lines. The star is variable over seven years with 0.5 mag variations over a year. We studied its spectral energy distribution together with five confirmed Luminous Blue Variables and Var A in M33 using homogeneous data and methods. We found the star's bolometric luminosity to be log(L/Lsun)~6.27, a surface temperature of T~16000K and black body temperatures of two dust components of T~900 and 420K. The new star has properties intermediate between the LBVs and VarA (probable cool hypergiant). In the same time it has a hot photosphere, LBV-like luminosity and an extensive circumstellar material (strong [CaII] lines). In these seven luminous variables in M33 we find the total range of the hot component luminosities is 1.0 dex, but that of the dust componets is 2.0 dex. We conclude that the dust phenomenon in the luminous variables is temporary and variable, and that dust activity may follow strong eruptions.Comment: 5 pages, 6 figures; MNRAS Letter accepte

Avalanche Merging and Continuous Flow in a Sandpile Model

A dynamical transition separating intermittent and continuous flow is observed in a sandpile model, with scaling functions relating the transport behaviors between both regimes. The width of the active zone diverges with system size in the avalanche regime but becomes very narrow for continuous flow. The change of the mean slope, Delta z, on increasing the driving rate, r, obeys Delta z ~ r^{1/theta}. It has nontrivial scaling behavior in the continuous flow phase with an exponent theta given, paradoxically, only in terms of exponents characterizing the avalanches theta = (1+z-D)/(3-D).Comment: Explanations added; relation to other model

The structure of hot gas in Cepheus B

By observing radiation-affected gas in the Cepheus B molecular cloud we probe whether the sequential star formation in this source is triggered by the radiation from newly formed stars. We used the dual band receiver GREAT onboard SOFIA to map [C II] and CO 13--12 and 11--10 in Cep B and compared the spatial distribution and the spectral profiles with complementary ground-based data of low-$J$ transitions of CO isotopes, atomic carbon, and the radio continuum. The interaction of the radiation from the neighboring OB association creates a large photon-dominated region (PDR) at the surface of the molecular cloud traced through the photoevaporation of C^+. Bright internal PDRs of hot gas are created around the embedded young stars, where we detect evidence of the compression of material and local velocity changes; however, on the global scale we find no indications that the dense molecular material is dynamically affected.Comment: Accepted for publication in A&A (SOFIA/GREAT special issue

Search for LBV Candidates in the M33 Galaxy

A total of 185 luminous blue variable (LBV) candidates with V < 18.5 and B-V < 0.35 are selected based on the photometrical Survey of Local Group Galaxies made by P. Massey et al. 2006. The candidates were selected using aperture photometry of H-alpha images. The primary selection criterion is that the prospective candidate should be a blue star with H-aplha emission. In order not to miss appreciably reddened LBV candidates, we compose an additional list of 25 presumably reddened (0.35 < B-V < 1.2, V < 18.5) emission star candidates. A comparison with the list of known variables in the M33 galaxy showed 29% of our selected candidates to be photometrically variable. We also find our list to agree well with the lists of emission-line objects obtained in earlier papers using different methods.Comment: 6 figure

Evaluation of bone mineral with dexa in youth soccer players

El objetivo de este estudio fue evaluar la densidad mineral ósea (DMO) y el contenido mineral óseo (CMO) de los segmentos corporales durante un periodo de entrenamiento de seis meses. Se evaluaron a 41 futbolistas juveniles profesionales en dos momentos, una al comienzo (TI) y otra al final (TF) de la intervención con el equipo de absorciometría dual de rayos X (DEXA). Se lograron aumentos significativos en la DMO en los segmentos corporales de la cadera, columna lumbar, triangulo de Ward, tronco y del cuerpo total (p<0.05). También se obtuvo un incremento significativo del CMO en la cadera, columna lumbar, pierna, tronco y costillas (p<0.05). El entrenamiento de futbol fortaleció el CMO y la DMO del hueso de la extremidad inferior y de la caja torácica, con lo cual el fútbol podría ser una actividad útil para la mejorar la mineralización y fortalecimiento del hueso, para prevenir lesiones y fracturasThe objective of this study was to assess bone mineral density (BMD) and bone mineral content (BMC) of body segments for a six months training period. 41 professional youth players were evaluated in two moments, one at the beginning (TI) and another at the end (TF) of the intervention with the dual energy x-ray absorptiometry equipment (DEXA). Significant increases in BMD were achieved in the body segments of the hip, lumbar spine, ward triangle, trunk and total body (p <0.05). There was also a significant increase in BMC in the hip, lumbar spine, leg, trunk and ribs (p <0.05). Soccer training strengthened the BMC and BMD of the lower limb bone and the rib cage, which could be a useful activity to improve bone mineralization and strengthening, to prevent injuries and fracture

INTEGRAL and XMM-Newton observations towards the unidentified MeV source GRO J1411-64

The COMPTEL unidentified source GRO J1411-64 was observed by INTEGRAL, and its central part, also by XMM-Newton. The data analysis shows no hint for new detections at hard X-rays. The upper limits in flux herein presented constrain the energy spectrum of whatever was producing GRO J1411-64, imposing, in the framework of earlier COMPTEL observations, the existence of a peak in power output located somewhere between 300-700 keV for the so-called low state. The Circinus Galaxy is the only source detected within the 4$\sigma$ location error of GRO J1411-64, but can be safely excluded as the possible counterpart: the extrapolation of the energy spectrum is well below the one for GRO J1411-64 at MeV energies. 22 significant sources (likelihood $> 10$) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the COMPTEL source position uncertainty make an association hard to quantify and thus risky. The unique peak of the power output at high energies (hard X-rays and gamma-rays) resembles that found in the SED seen in blazars or microquasars. However, an analysis using a microquasar model consisting on a magnetized conical jet filled with relativistic electrons which radiate through synchrotron and inverse Compton scattering with star, disk, corona and synchrotron photons shows that it is hard to comply with all observational constrains. This and the non-detection at hard X-rays introduce an a-posteriori question mark upon the physical reality of this source, which is discussed in some detail

Left Ventricle Quantification with Cardiac MRI: Deep Learning Meets Statistical Models of Deformation

Deep learning has been widely applied for left ventricle (LV) analysis, obtaining state of the art results in quantification through image segmentation. When the training datasets are limited, data augmentation becomes critical, but standard augmentation methods do not usually incorporate the natural variation of anatomy. In this paper we propose a pipeline for LV quantification applying our data augmentation methodology based on statistical models of deformations (SMOD) to quantify LV based on segmentation of cardiac MR (CMR) images, and present an in-depth analysis of the effects of deformation parameters in SMOD performance. We trained and evaluated our pipeline on the MICCAI 2019 Left Ventricle Full Quantification Challenge dataset, and achieved average mean absolute error (MAE) for areas, dimensions, regional wall thickness and phase of 106 mm2, 1.52 mm, 1.01 mm and 8.0% respectively in a 3-fold cross-validation experiment

Curvas de crecimiento de cereales forrajeros de invierno. I. Avena (Avena sativa L.)

The trial was carried out to study dry matter yields of 6 oat (Avena sativa L.) cultivars, and the seasonal growth distribution. Green standing crop was clipped every 7 days in 90 plots arranged at random in 5 series with 3 repetitions each. The environmental conditions determined a very short growing period, principally in early cultivars. Significant differences (P &lt; 0,05) were observed between Millauquén INTA (2,164.0 kg MS/ha) and 82/2866 Sv. and Suregrain cultivars (1,431.5 and 1,464.8 kg MS/ha, respectively). The growth equations of each cultivar was determined. The highest growth rate (28.54 kg MS/ha/day) corresponded to Millauquén INTA, and was shown at early june. Millauquén INTA, Sra. 74/76864 and Moregrain showed a better dry matter distribution than the resto during the entire growth season.El ensayo se realizó con el propósito de estudiar en forma comparativa el rendimiento de materia seca de 6 variedades cultivadas de avena (Avena sativa L.) y la distribución estacional del mismo. Se adoptó una metodología de cortes secuenciales, trabajando con 90 parcelas dispuestas en 5 series con 3 repeticiones. Las condiciones ambientales determinaron un acortamiento pronunciado de la estación de crecimiento, particularmente en los cultivares precoces. Existieron diferencias significativas (P &lt; 0;05) entre la variedad cultivada Millauquén INTA (2.164,0 kg MS/ha) y los cultivares 82/2866 Sv. y Suregrairi (1.431,5 y 1.464,8 kg MS/ha, respectivamente). Se determinaron las ecuaciones descriptivas del crecimiento para cada cultivar. La máxima tasa de producción (28,54 kg MS/ha/día correspondió a la variedad cultivada Millauquén INTA, a comienzos de junio. Esta variedad, al igual que los cultivares Sra.74 /76864 y Moregrain, mostró una distribución más uniforme de la materia seca a través del tiempo