3,785 research outputs found
Do Young Neutron Stars Which Show Themselves As AXPs, SGRs and Radio Pulsars Accrete?
We examined the fall-back disk models, and in general accretion, proposed to
explain the properties of anomalous X-ray pulsars (AXPs), soft gamma repeaters
(SGRs), and radio pulsars (PSRs). We checked the possibility of some gas
remaining around the neutron star after the supernova explosion. We also
compared AXPs and SGRs with the X-ray pulsars in X-ray binaries. We conclude
the existing models of accretion from a fall-back disk are insufficient to
explain the nature of AXPs/SGRs, particularly the SGR bursts. We also discussed
the proposed model of combination of magnetic dipole radiation and propeller
torques in order to explain the evolution of radio pulsars on the P-\.{P}
diagram. The predictions of this model contradict the observational data.Comment: 16 Pages, 1 Figur
Emitter Location Finding using Particle Swarm Optimization
Using several spatially separated receivers, nowadays positioning techniques, which are implemented to determine the location of the transmitter, are often required for several important disciplines such as military, security, medical, and commercial applications. In this study, localization is carried out by particle swarm optimization using time difference of arrival. In order to increase the positioning accuracy, time difference of arrival averaging based two new methods are proposed. Results are compared with classical algorithms and Cramer-Rao lower bound which is the theoretical limit of the estimation error
Smart Textiles for Soldier of the Future
The textile-based materials, equipped with nanotechnology and electronics, have a majorrole in the development of high-tech milltary uniforms and materials. Active intelligent textilesystems, integrated to electronics, have the capacity of improving the combat soldiers performanceby sensing, adopting themselves and responding to a situational combat need allowing thecombat soldiers to continue their mission. Meantime, smart technologies aim to help soldiersdo everyth~ngth ey need to do with a less number of equipment and a lighter load. In this study,recent developments on smart garments, especially designed for military usage owing to theirelectronic functions, and intelligent textlle-based materials that can be used in battlefield, areintroduced
Early phases of different types of isolated neutron star
Two Galactic isolated strong X-ray pulsars seem to be in the densest
environments compared to other types of Galactic pulsar. X-ray pulsar
J1846-0258 can be in an early phase of anomalous X-ray pulsars and soft gamma
repeaters if its average braking index is ~1.8-2.0. X-ray pulsar J1811-1925
must have a very large average braking index (n~11) if this pulsar was formed
by SN 386AD. This X-ray pulsar can be in an early phase of evolution of the
radio pulsars located in the region P~50-150 ms and \.{P}~10
s/s of the P-\.{P} diagram. X-ray/radio pulsar J0540-69 seems to be evolving in
the direction to the dim isolated thermal neutron star region on the P-\.{P}
diagram. Possible progenitors of different types of neutron star are also
discussed.Comment: to appear in the International Journal of Modern Physics
An Extremely Uncommon Case of Parasitic Infection Presenting as Eosinophilic Ascites in a Young Patient
We report the case of a 24-year-old male patient admitted for recent ascites and splenomegaly of unknown origin. The patient was referred to our institution with complaints of diarrhea, epigastric pain, abdominal cramping and weight loss over the past three weeks. The acute onset presented with colicky abdominal pain and peritoneal effusion. History revealed reduced appetite and weight gain of 7 kg over the last one month. His past medical history and family history was negative. He had no history of alcohol abuse or viral hepatitis infection. Laboratory data revealed normal transaminases and bilirubin levels, and alkaline phosphatase and gammaglutamyltransferase were within normal range. A diagnostic laparoscopy was performed which showed free peritoneal fluid and normal abdominal viscera. Upper gastrointestinal system endoscopy performed a few days later revealed diffuse severe erythematous pangastritis and gastroduodenal gastric reflux. Duodenal biopsies showed chronic nonspecific duodenitis. Antrum and corpus biopsies showed chronic gastritis. The ascitic fluid was straw-colored and sterile with 80% eosinophils. Stool exam was negative for parasitic infection. Treatment with albendazole 400 mg twice daily for 5 days led to the disappearance of ascites and other signs and symptoms. Three months after albendazole treatment the eosinophilic cell count was normal. The final diagnosis was consistent with parasitic infection while the clinical, sonographic and histological findings suggested an eosinophilic ascites. We emphasize the importance of excluding parasitic infection in all patients with eosinophilic ascites. We chose an alternative way (albendazole treatment) to resolve this clinical picture. With our alternative way for excluding this parasitic infection, we treated the patient and then found the cause
Simulation of the CMS Resistive Plate Chambers
The Resistive Plate Chamber (RPC) muon subsystem contributes significantly to
the formation of the trigger decision and reconstruction of the muon trajectory
parameters. Simulation of the RPC response is a crucial part of the entire CMS
Monte Carlo software and directly influences the final physical results. An
algorithm based on the parametrization of RPC efficiency, noise, cluster size
and timing for every strip has been developed. Experimental data obtained from
cosmic and proton-proton collisions at TeV have been used for
determination of the parameters. A dedicated validation procedure has been
developed. A good agreement between the simulated and experimental data has
been achieved.Comment: to be published in JINS
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Measurement of double-differential cross sections for top quark pair production in pp collisions at [Formula: see text][Formula: see text] and impact on parton distribution functions.
Normalized double-differential cross sections for top quark pair ([Formula: see text]) production are measured in pp collisions at a centre-of-mass energy of 8[Formula: see text] with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7[Formula: see text]. The measurement is performed in the dilepton [Formula: see text] final state. The [Formula: see text] cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and [Formula: see text] system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured [Formula: see text] cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution
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Measurement of the [Formula: see text] production cross section using events in the [Formula: see text] final state in pp collisions at [Formula: see text].
The cross section of top quark-antiquark pair production in proton-proton collisions at [Formula: see text] is measured by the CMS experiment at the LHC, using data corresponding to an integrated luminosity of 2.2[Formula: see text]. The measurement is performed by analyzing events in which the final state includes one electron, one muon, and two or more jets, at least one of which is identified as originating from hadronization of a b quark. The measured cross section is [Formula: see text], in agreement with the expectation from the standard model
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