1,732 research outputs found
Instruments of RT-2 Experiment onboard CORONAS-PHOTON and their test and evaluation IV: Background Simulations using GEANT-4 Toolkit
Hard X-ray detectors in space are prone to background signals due to the
ubiquitous cosmic rays and cosmic diffuse background radiation that
continuously bombards the satellites which carry the detectors. In general, the
background intensity depends on the space environment as well as the material
surrounding the detectors. Understanding the behavior of the background noise
in the detector is very important to extract the precise source information
from the detector data. In this paper, we carry out Monte Carlo simulations
using the GEANT-4 toolkit to estimate the prompt background noise measured with
the detectors of the RT-2 Experiment onboard the CORONAS-PHOTON satellite.Comment: 21 pages, 10 figures, Accepted for publication in Experimental
Astronomy (in press
Temperature dependent asymmetry of the nonlocal spin-injection resistance: evidence for spin non-conserving interface scattering
We report nonlocal spin injection and detection experiments on mesoscopic
Co-Al2O3-Cu spin valves. We have observed a temperature dependent asymmetry in
the nonlocal resistance between parallel and antiparallel configurations of the
magnetic injector and detector. This strongly supports the existence of a
nonequilibrium resistance that depends on the relative orientation of the
detector magnetization and the nonequilibrium magnetization in the normal metal
providing evidence for increasing interface spin scattering with temperature.Comment: 5 pages, 4 figures, accepted for publication in PRL, minor
corrections (affiliation, acknowledgements, typo
The Oxidative Decarboxylation Of Polyaminocarboxylic Acids - II. A Comparative Kinetic Study Of The Oxidation Of NTA, EDTA, CDTA And Dtpa With Cerium(IV) In Sulfuric Acid Media
The rates of oxidation of four chelating agents, NTA, EDTA, CDTA, and DTPA with Ce(IV), in sulfuric acid media, were determined spectrophotometrically by a stopped-flow technique. The reductive ability is in the order CDTA \u3e EDTA \u3e DTPA \u3e NTA. The influence of varying the acidity of the medium was studied, and in each case a maximum in the rate constant vs. [H+] plot was observed. A possible interpretation of the reactivities and the influence of acidity is advanced. © 1971 Springer-Verlag
The Oxidative Decarboxylation Of Polyaminocarboxylic Acids - I. A Study Of The Reaction Of Ethylenedinitrilotetraacetic Acid (EDTA) With Cerium (IV) In Acid Solution
The reaction between Ce(IV) and EDTA was followed titrimetrically and spectrophotometrically and was found to occur in stages. Four equivalents of Ce(IV) are reduced per mole of EDTA almost instantaneously at room temperature. With increasing temperature and reaction time an ultimate of about 14 equivalents of Ce (IV) is consumed per mole of EDTA. Carbon dioxide, formaldehyde, and other yet unidentified compounds are the products of oxidation of EDTA. The kinetics of the reaction in aqueous sulfuric acid was studied over the temperature range 11.7°-40°C by a spectrophotometric technique. The effects of the acidity of the medium and of added salts are reported. © 1969 Springer-Verlag
Xanthogranulomatous Appendicitis in a Child: Report of a Case and Review of the Literature
Xanthogranulomatous inflammation is a well-described inflammatory process, which may involve any organ but is most frequently encountered in the gall bladder and the kidney. There are rare reports of xanthogranulomatous appendicitis (XA) in the adult population, but only one brief mention of such a diagnosis in a child. In this report, we describe the case of an 11-year-old boy who presented with clinical signs and symptoms of acute appendicitis necessitating appendectomy. Upon microscopic examination, the appendix showed the typical features of XA. To the best of our knowledge, this is the first well-described case XA in a noninterval appendix in a child. We also reviewed the limited medical literature on the subject
Thermally activated magnetization reversal in monoatomic magnetic chains on surfaces studied by classical atomistic spin-dynamics simulations
We analyze the spontaneous magnetization reversal of supported monoatomic
chains of finite length due to thermal fluctuations via atomistic spin-dynamics
simulations. Our approach is based on the integration of the Landau-Lifshitz
equation of motion of a classical spin Hamiltonian at the presence of
stochastic forces. The associated magnetization lifetime is found to obey an
Arrhenius law with an activation barrier equal to the domain wall energy in the
chain. For chains longer than one domain-wall width, the reversal is initiated
by nucleation of a reversed magnetization domain primarily at the chain edge
followed by a subsequent propagation of the domain wall to the other edge in a
random-walk fashion. This results in a linear dependence of the lifetime on the
chain length, if the magnetization correlation length is not exceeded. We
studied chains of uniaxial and tri-axial anisotropy and found that a tri-axial
anisotropy leads to a reduction of the magnetization lifetime due to a higher
reversal attempt rate, even though the activation barrier is not changed.Comment: 2nd version contains some improvements and new Appendi
LSR0602+3910 - Discovery of a Bright Nearby L-type Brown Dwarf
We report the discovery of LSR0602+3910, an L dwarf of class L1. The object
was initially identified by Lepine et al. (2002) as a new high proper motion
star lying close to the Galactic plane. Its 2MASS J-K_s=1.43 is consistent with
an L dwarf, which we now confirm spectroscopically. In addition, we see a
signature of Li I absorption, making LSR0602+3910 a brown dwarf, one of the
brightest known (K_s=10.86). Among L dwarfs it is second in brightness to the
combined light of 2MASS 0746+20, a close binary system. We see no indication
that LSR0602+3910 is a binary, although high-resolution imaging will be
required to confirm this. Spectroscopic and photometric distance estimates
agree very well, placing LSR0602+3910 at d=10.6+-0.8 pc. LSR0602+3910 was most
likely missed in previous searches because of its proximity to the plane, the
region that most searches avoided. We estimate that some 40% of bright L dwarfs
are missed because of this selection effect.Comment: Accepted to ApJL. Revised version discusses LP 944-20 and has an
updated L-dwarf tabl
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Reliable intraocular pressure measurement using automated radio-wave telemetry
Purpose To present an autonomous intraocular pressure (IOP) measurement technique using a wireless implantable transducer (WIT) and a motion sensor. Methods: The WIT optical aid was implanted within the ciliary sulcus of a normotensive rabbit eye after extracapsular clear lens extraction. An autonomous wireless data system (AWDS) comprising of a WIT and an external antenna aided by a motion sensor provided continuous IOP readings. The sensitivity of the technique was determined by the ability to detect IOP changes resulting from the administration of latanoprost 0.005% or dorzolamide 2%, while the reliability was determined by the agreement between baseline and vehicle (saline) IOP. Results: On average, 12 diurnal and 205 nocturnal IOP measurements were performed with latanoprost, and 26 diurnal and 205 nocturnal measurements with dorzolamide. No difference was found between mean baseline IOP (13.08±2.2 mmHg) and mean vehicle IOP (13.27±2.1 mmHg) (P=0.45), suggesting good measurement reliability. Both antiglaucoma medications caused significant IOP reduction compared to baseline; latanoprost reduced mean IOP by 10% (1.3±3.54 mmHg; P<0.001), and dorzolamide by 5% (0.62±2.22 mmHg; P<0.001). Use of latanoprost resulted in an overall twofold higher IOP reduction compared to dorzolamide (P<0.001). Repeatability was ±1.8 mmHg, assessed by the variability of consecutive IOP measurements performed in a short period of time (≤1 minute), during which the IOP is not expected to change. Conclusion: IOP measurements in conscious rabbits obtained without the need for human interactions using the AWDS are feasible and provide reproducible results
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