11,068 research outputs found
Identification of red supergiants in nearby galaxies with mid-IR photometry
The role of episodic mass loss in massive star evolution is one of the most
important open questions of current stellar evolution theory. Episodic mass
loss produces dust and therefore causes evolved massive stars to be very
luminous in the mid-infrared and dim at optical wavelengths. We aim to increase
the number of investigated luminous mid-IR sources to shed light on the late
stages of these objects. To achieve this we employed mid-IR selection criteria
to identity dusty evolved massive stars in two nearby galaxies. The method is
based on mid-IR colors, using 3.6 {\mu}m and 4.5 {\mu}m photometry from
archival Spitzer Space Telescope images of nearby galaxies and J-band
photometry from 2MASS. We applied our criteria to two nearby star-forming dwarf
irregular galaxies, Sextans A and IC 1613, selecting eight targets, which we
followed up with spectroscopy. Our spectral classification and analysis yielded
the discovery of two M-type supergiants in IC 1613, three K-type supergiants
and one candidate F-type giant in Sextans A, and two foreground M giants. We
show that the proposed criteria provide an independent way for identifying
dusty evolved massive stars, that can be extended to all nearby galaxies with
available Spitzer/IRAC images at 3.6 {\mu}m and 4.5 {\mu}m.Comment: 8 pages, 4 figures, A&A in pres
Long-Term Safety of Tedizolid in a Patient With Spondilodiscitis After Switch From Linezolid Due to Toxicity
The patient is a 57-year-old man with liver cirrhosis, Bricker anastomosis after a radical cystoprostatectomy and, a history of bacteremias caused by extended-spectrum -lactamase-positive Escherichia coli, Enterococcus faecium, and Candida albicans. He presented with persistent low back pain and was diagnosed with vertebral osteomyelitis, for which he received ertapenem-linezolid treatment. However, after 20 days, linezolid had to be discontinued because of myelotoxicity and metabolic acidosis. The patient was switched to tedizolid, which, in combination with ertapenem, was successfully given for 114 days until biopsy showed no growth of gram-positive cocci. We conclude that tedizolid can be an alternative to linezolid in case of toxicity, especially in long-term treatments
Geometry Diagnostics of a Stellar Flare from Fluorescent X-rays
We present evidence of Fe fluorescent emission in the Chandra HETGS spectrum
of the single G-type giant HR 9024 during a large flare. In analogy to solar
X-ray observations, we interpret the observed Fe K line as being
produced by illumination of the photosphere by ionizing coronal X-rays, in
which case, for a given Fe photospheric abundance, its intensity depends on the
height of the X-ray source. The HETGS observations, together with 3D Monte
Carlo calculations to model the fluorescence emission, are used to obtain a
direct geometric constraint on the scale height of the flaring coronal plasma.
We compute the Fe fluorescent emission induced by the emission of a single
flaring coronal loop which well reproduces the observed X-ray temporal and
spectral properties according to a detailed hydrodynamic modeling. The
predicted Fe fluorescent emission is in good agreement with the observed value
within observational uncertainties, pointing to a scale height \rstar. Comparison of the HR 9024 flare with that recently observed on II
Peg by Swift indicates the latter is consistent with excitation by X-ray
photoionization.Comment: accepted for publication on the Astrophysical Journal Letter
KINETIC AND KINEMATIC ANALYSIS OF THE DOMINANT AND NON-DOMINANT KICKING LEG IN THE TAEKWONDO ROUNDHOUSE KICK
The purpose of this study was to examine kinematic variables relevant to kick performance with the dominant and non-dominant leg, in a roundhouse kick measured from three execution distances. Forty-three taekwondo athletes that had competitive taekwondo experience participated in the study. A dependent t-test indicated that there were no differences between extremities at any distance (p > .01). Based on these results, competitive taekwondo players do not seem to reveal differences in limb kinematics. The results also showed the influence of the distance from which the dominant leg explains a larger percentage of variance in reaction time (24%), execution time (20%) and total response time (60%) of the non-dominant leg from a short distance, whereas regarding impact force (22%), this higher percentage is explained from a long distance
Face Centered Anisotropic Surface Impedance Boundary Conditions in FDTD
Thin sheet models are essential to allow shielding effectiveness of composite enclosures and vehicles to be modelled. Thin dispersive sheets are often modeled using surface impedance models in finite-difference time-domain (FDTD) codes in order to deal efficiently with the multi-scale nature of the overall structure. Such boundary conditions must be applied to collocated tangential electric and magnetic fields on either side of the surface; this is usually done on the edges of the FDTD mesh cells at the electric field sampling points. However, these edge based schemes are difficult to implement accurately on stair-cased surfaces. Here we present a novel face centered approach to the collocation of the fields for the application of the boundary condition. This approach naturally deals with the ambiguities in the surface normal that arise at the edges on stair-cased surfaces, allowing a simpler implementation. The accuracy of the new scheme is compared to edge based and conformal approaches using both planar sheet and spherical shell canonical test cases. Stair-casing effects are quantified and the new face-centered scheme is shown have up to 3 dB lower error than the edge based approach in the cases considered, without the complexity and computational cost of conformal techniques
Relationship Between Jump Capacity and Performance in BMX Cycling
The objective of this study is to assess the relationship between the results obtained on different vertical jump tests and the top score recorded during a BMX (Bicycle Moto-Cross) test and the rider''s performance. To do so, 10 BMX pilots participated in this study; 5 regarded as the elite group (EG) (age: 18.8 +/- 3.7, weight: 68.4 +/- 8.5 kg, height: 174 +/- 9 cm and previous BMX experience: 8 +/- 3.8 years) and 5 regarded as the recreational group (RG) (age: 19.8 +/- 4.8, weight: 69.2 +/- 11.7 kg, height: 170 +/- 9 cm, previous BMX experience: 4.2 +/- 1.3 years). Vertical jump capacity was obtained using the Bosco protocol, i.e. vertical squat jump (SJ), vertical countermovement jump (CMJ), drop jump (DJ) and repetitive jump (RJ), and time in race in a BMX circuit was determined. The results indicate a direct relationship between the time used to complete the circuit and the height of the jump reached in SJ (r: -.801; p:.017), CMJ (r : -.798; p :.018) and DJ (r : -.782; p:.022). This all suggests that assessing jump capacity using the Bosco test may be a useful tool for assessing BMX performance
Energy mapping of large refrigerated warehouses co-located with renewable energy sources across Europe
Powering refrigerated warehouses by renewable energy sources (RES) turns from an extravagancy to a routine. RES intermittency requires suitable energy storage for both off-grid and on-grid applications. Cryogenic energy storage, integrated synergistically with RES and large refrigerated warehouses, is a promising environmentally friendly technology (addressed by the EU CryoHub project). Hence, studies were carried out to identify where large energy-intensive refrigerated warehouses are situated across Europe and how much power they consume. By employing diverse instruments and data sources, some 1049 warehouses were established, while 503 energy intensive ones were mapped and further co-located with 3200 solar PV and 11700 onshore wind parks to discover the best areas for RES integration across EU28. As compared with similar international surveys, the CryoHub statistics covers simultaneously warehouse capacity, geographical location and energy data, which permit a comprehensive analysis and strategic planning in both food refrigeration and energy sectors
Hamiltonian embedding of the massive noncommutative U(1) theory
We show that the massive noncommutative U(1) can be embedded in a gauge
theory by using the BFFT Hamiltonian formalism. By virtue of the peculiar
non-Abelian algebraic structure of the noncommutative massive U(1) theory,
several specific identities involving Moyal commutators had to be used in order
to make the embedding possible. This leads to an infinite number of steps in
the iterative process of obtaining first-class constraints. We also shown that
the involutive Hamiltonian can be constructed.Comment: 8 pages, Revtex (multicol
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