2,377 research outputs found
The superficial brachial artery : a case report
A superficial brachial artery is an anomalous branch of the brachial artery that runs superficial to the median nerve; it is usually associated with a deep brachial branch that runs deep to this nerve. A case is described of a superficial brachial artery. It is of the type where the artery terminates in the cubital fossa by division into radial and ulnar arteries. It is associated with a superficial ulnar artery, and a deep brachial artery that is continued into the forearm as the common interosseous artery, a rare occurrence. The clinical importance and the dangers of this vascular anomaly are discussed. In reparative surgery, an accurate knowledge of the relationship, course and particularly the possible variations of the brachial artery is of considerable importance.peer-reviewe
Blue straggler masses from pulsation properties. II. Topology of the Instability Strip
We present a new set of nonlinear, convective radial pulsation models for
main sequence stars computed assuming three metallicities: Z=0.0001, 0.001 and
0.008. These chemical compositions bracket the metallicity of stellar systems
hosting SX Phoenicis stars (SXPs or pulsating Blue Stragglers), namely Galactic
globular clusters and nearby dwarf spheroidals. Stellar masses and luminosities
of the pulsation models are based on alpha--enhanced evolutionary tracks from
the BASTI website. We are able to define the topology of the instability strip
(IS), and in turn the pulsation relations for the first four pulsation modes.
We found that third overtones approach a stable nonlinear limit cycle.
Predicted and empirical IS agree quite well in the case of 49 SXPs belonging to
omega Cen. We used theoretical Period-Luminosity relations in B,V bands to
identify their pulsation mode. We assumed Z=0.001 and Z=0.008 as mean
metallicities of SXPs in omega Cen. We found respectively 13-15 fundamental,
22-6 first and 9-4 second overtone modes. Five are unstable in the third
overtone mode only for Z=0.001. Using the above mode identification and
applying the proper mass-dependent Period-Luminosity relations we found masses
ranging from ~1.0 to 1.2 Mo (=1.12, sigma=0.04 Mo) and from ~1.2 to 1.5 Mo
(=1.33, sigma=0.03 Mo) for Z=0.001 and 0.008 respectively. Our investigation
supports the use of evolutionary tracks to estimate of SXP masses. We will
extend our analysis to higher Helium content that may have an impact in our
understanding of the BSS formation scenario.Comment: 14 pages, 5 figures, 7 tables, ApJ accepte
Biofuel production with castor bean: A win-win strategy for marginal land
The urgency to reduce resource depletion and waste production is expected to lead to an economy based on renewable resources. Biofuels, for instance, are a great green alternative to fossil fuel, but they are currently derived from edible vegetable oils such as soybean, palm, and sunflower. Concerns have been raised about the social-economic implication and ecological impacts of biodiesel production. Cultivating new lands as biodiesel feedstock rather than food supply, with the consequent increase in food prices, leads to so-called indirect land-use change (ILUC). Establishing bioenergy crops with phytoremediation ability on contaminated soils offers multiple benefits such as improving soil properties and ecosystem services, decreasing soil erosion, and diminishing the dispersion of potentially toxic elements (PTEs) into the environment. Castor bean is an unpalatable, high-biomass plant, and it has been widely demonstrated to possess phytoremediation capability for several PTEs. Castor bean can grow on marginal lands not suitable for food crops, has multiple uses as a raw material, and is already used in biodiesel production. These characteristics make it perfect for sustainable biodiesel production. Linking biofuel production with environmental remediation can be considered a win-win strategy
Additive manufacturing of PLA to mimic the thrust force of mandibular bone during drilling
Edentulism is a condition that results in the partial or total loss of teeth. It may lead to problems during chewing and be a cause of self-isolation and low self-esteem. Edentulism can be resolved both with removable prostheses (dentures) and fixed implants, with the latter being more efficient. The installation of a fixed implant involves a real surgical operation in which the jaw/mandibular bone is drilled through a special drill. One of the main cautions the surgeon must have during the operation is not to sever the nerves during the drilling. Given the composition of the bone is different in each person, the drilling thrust force is variable and controlling its movement can sometimes be complicated. Therefore, being able to test the operation on a dummy may reduce the number of errors. Additive manufacturing with its high degree of customization and ability to produce objects with almost no geometrical limitations could provide the required features to realize the dummy. In this work, the drilling properties of samples made in PLA through Fused Filament Fabrication (FFF) were studied. The samples were designed to mimic the composition of the bone. Specifically, a thin, hard, and denser outer layer and a 25% internal filling were adopted. The samples were drilled with a dental drill properly connected to a collaborative robot
Variable stars in Terzan 5: additional evidence of multi-age and multi-iron stellar populations
Terzan 5 is a complex stellar system in the Galactic bulge, harboring stellar
populations with very different iron content ({\Delta}[Fe/H] ~1 dex) and with
ages differing by several Gyrs. Here we present an investigation of its
variable stars. We report on the discovery and characterization of three RR
Lyrae stars. For these newly discovered RR Lyrae and for six Miras of known
periods we provide radial velocity and chemical abundances from spectra
acquired with X-SHOOTER at the VLT. We find that the three RR Lyrae and the
three short period Miras (P<300 d) have radial velocity consistent with being
Terzan 5 members. They have sub-solar iron abundances and enhanced
[{\alpha}/Fe], well matching the age and abundance patterns of the 12 Gyr
metal-poor stellar populations of Terzan 5. Only one, out of the three long
period (P>300 d) Miras analyzed in this study, has a radial velocity consistent
with being Terzan 5 member. Its super-solar iron abundance and solar-scaled
[{\alpha}/Fe] nicely match the chemical properties of the metal rich stellar
population of Terzan 5 and its derived mass nicely agrees with being several
Gyrs younger than the short period Miras. This young variable is an additional
proof of the surprising young sub-population discovered in Terzan 5.Comment: 20 pages, 4 figures, in press on the Ap
Efficient polarization squeezing in optical fibers
We report on a novel and efficient source of polarization squeezing using a
single pass through an optical fiber. Simply passing this Kerr squeezed beam
through a carefully aligned lambda/2 waveplate and splitting it on a
polarization beam splitter, we find polarization squeezing of up to 5.1 +/- 0.3
dB. The experimental setup allows for the direct measurement of the squeezing
angle.Comment: 4 pages, 4 figure
Experimental performance comparison between circular and elliptical tubes in evaporative condensers
In refrigeration systems, evaporative condensers have two main advantages compared to other condensation heat exchangers: They operate at lower condensation temperature than traditional air-cooled condensers and require a lower quantity of water and pumping power compared to evaporative towers. The heat and mass transfer that occur on tube batteries are difficult to study. The aim of this work is to apply an experimental approach to investigate the performance of an evaporative condenser on a reduced scale by means of a test bench, consisting of a transparent duct with a rectangular test section in which electric heaters, inside elliptical pipes (major axis 32 mm, minor axis 23 mm), simulate the presence of the refrigerant during condensation. By keeping the water conditions fixed and constant, the operating conditions of the air and the inclination of the heat transfer geometry were varied, and this allowed to carry out a sensitivity analysis, depending on some of the main parameters that influence the thermo-fluid dynamic phenomena, as well as a performance comparison. The results showed that the heat transfer increases with the tube surface exposed directly to the air as a result of the increase in their inclination, that has been varied in the range 0–20°. For the investigated conditions, the average increase, resulting by the inclination, is 28%
The power of teaming up HST and Gaia:The first proper motion measurement of the distant cluster NGC 2419
Aims: We present the first measurement of the proper motion and orbit of the
very distant and intriguing globular cluster NCG 2419. Methods: We have
combined data from HST and Gaia DR1 to derive the relative proper motions of
stars in the direction to the cluster. To tie to an absolute reference frame we
have used a background galaxy located in the field. Results: We find the
absolute proper motion of NGC 2419 to be ,
)=() mas/yr. We have integrated the
orbit of the cluster in a Galactic potential and found it to oscillate between
53 kpc and 98 kpc on a nearly polar orbit. This makes it very
likely that NGC 2419 is a former cluster of the Sagittarius dwarf spheroidal
galaxy, also because it shares the same sense of rotation around the Milky Way.Comment: 5 pages, 4 figures, accepted for publication by A&A Letter
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