4,150 research outputs found
Manganese-56 coincidence-counting facility precisely measures neutron-source strength
Precise measurement of neutron-source strength is provided by a manganese 56 coincidence-counting facility using the manganese-bath technique. This facility combines nuclear instrumentation with coincidence-counting techniques to handle a wide variety of radioisotope-counting requirements
Molecular vibration in cold collision theory
Cold collisions of ground state oxygen molecules with Helium have been
investigated in a wide range of cold collision energies (from 1 K up to 10
K) treating the oxygen molecule first as a rigid rotor and then introducing the
vibrational degree of freedom. The comparison between the two models shows that
at low energies the rigid rotor approximation is very accurate and able to
describe all the dynamical features of the system. The comparison between the
two models has also been extended to cases where the interaction potential He -
O is made artificially stronger. In this case vibration can perturb rate
constants, but fine-tuning the rigid rotor potential can alleviate the
discrepancies between the two models.Comment: 11 pages, 3 figure
Estabilidade de carotenoides em derivados de milho biofortificado com precursores de vitamina A durante o armazenamento.
Chemical reactivity of ultracold polar molecules: investigation of H + HCl and H + DCl collisions
Quantum scattering calculations are reported for the H+HCl(v,j=0) and
H+DCl(v,j=0) collisions for vibrational levels v=0-2 of the diatoms.
Calculations were performed for incident kinetic energies in the range 10-7 to
10-1 eV, for total angular momentum J=0 and s-wave scattering in the entrance
channel of the collisions. Cross sections and rate coefficients are
characterized by resonance structures due to quasibound states associated with
the formation of the H...HCl and H...DCl van der Waals complexes in the
incident channel. For the H+HCl(v,j=0) collision for v=1,2, reactive scattering
leading to H_2 formation is found to dominate over non-reactive vibrational
quenching in the ultracold regime. Vibrational excitation of HCl from v=0 to
v=2 increases the zero-temperature limiting rate coefficient by about 8 orders
of magnitude.Comment: 9 pages, 6 figures, submitted to Euro. Phys. J. topical issue on
"Ultracold Polar Molecules: Formation and Collisions
Polarization in the inner region of Pulsar Wind Nebulae
We present here the first effort to compute synthetic synchrotron
polarization maps of Pulsar Wind Nebulae (PWNe). Our goal is to highlight how
polarization can be used as an additional diagnostic tool for the flow
structure in the inner regions of these nebulae. Recent numerical simulations
suggest the presence of flow velocities ~0.5 c in the surroundings of the
termination shock, where most of the high energy emission comes from. We
construct polarization maps taking into account relativistic effects like
Doppler boosting and position angle swing. The effect of different bulk
velocities is clarified with the help of a toy-model consisting of a uniformly
emitting torus. We also present a map based on recent numerical simulations of
the entire nebula and compare it with presently available data. The comparison
with upcoming high resolution observations could provide new insight into the
inner structure of the nebula and put constraints on the geometrical properties
of the magnetic field.Comment: Accepted for publication on A&A, 6 pages, 2 figure
Retenção de carotenoides após processamento via moagem a seco de grãos de milho biofortificado.
Paraneoplastic necrotizing myopathy associated with adenocarcinoma of the lung - a rare entity with atypical onset: a case report.
Introduction. Inflammatory myopathies (such as dermatomyositis and polymyositis) are well-recognized paraneoplastic syndromes. However, paraneoplastic necrotizing myopathy is a more recently defined clinical entity, characterized by rapidly progressive, symmetrical, predominantly proximal muscle weakness with severe disability, and associated with a marked increase in serum muscle enzyme levels. Paraneoplastic necrotizing myopathy requires muscle biopsy for diagnosis, which typically shows massive necrosis of muscle fibers with limited or absent inflammatory infiltrates. Case presentation. We report the case of an 82-year-old Italian-born Caucasian man who was admitted to hospital because of heart failure and two drop attacks. Over the following days, he developed progressive severe weakness, dysphagia, and dysphonia. Testing showed increasing serum muscle enzyme levels. Electromyography showed irritative myopathy of the proximal muscles and sensorimotor polyneuropathy. Muscle biopsy (left vastus lateralis) showed massive necrosis of muscle fibers with negligible inflammatory infiltrates, complement membrane attack complex deposition on endomysial capillaries, and moderate upregulation of major histocompatibility complex-I. Computed tomography of the thorax showed a nodular mass in the apex of the right lung. The patient was diagnosed with paraneoplastic necrotizing myopathy. In spite of high-dose corticoid therapy, he died 1 month later because of his aggressive cancer. Subsequent electron microscopic examination of a muscle biopsy specimen showed thickened walls and typical pipestem changes of the endomysial capillaries, with swollen endothelial cells. Poorly differentiated adenocarcinoma of the lung was confirmed on post-mortem histological examination. Conclusions: Paraneoplastic necrotizing myopathy is a rare syndrome with outcomes ranging from fast progression to complete recovery. Treatment with corticosteroids is often ineffective, and prognosis depends mainly on the characteristics of the underlying cancer. This case shows that paraneoplastic necrotizing myopathy may have an atypical appearance, and should be considered in elderly patients with neoplastic disease. In this case, the diagnosis was delayed by the unusual clinical picture that suggested heart disease rather than muscle disease
The Evolution of FTK, a Real-Time Tracker for Hadron Collider Experiments
We describe the architecture evolution of the highly-parallel dedicated
processor FTK, which is driven by the simulation of LHC events at high
luminosity (1034 cm-2 s-1). FTK is able to provide precise on-line track
reconstruction for future hadronic collider experiments. The processor,
organized in a two-tiered pipelined architecture, execute very fast algorithms
based on the use of a large bank of pre-stored patterns of trajectory points
(first tier) in combination with full resolution track fitting to refine
pattern recognition and to determine off-line quality track parameters. We
describe here how the high luminosity simulation results have produced a new
organization of the hardware inside the FTK processor core.Comment: 11th ICATPP conferenc
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