1,428 research outputs found
Lamp enables measurement of oxygen concentration in presence of water vapor
Open-electrode ultraviolet source lamp radiates sufficient energy at 1800 angstroms and 1470 angstroms for use in a double-beam, duel-wavelength oxygen sensor. The lamp is filled with xenon at a pressure of 100 mm of Hg
Gravitational Couplings of Intrinsic Spin
The gravitational couplings of intrinsic spin are briefly reviewed. A
consequence of the Dirac equation in the exterior gravitational field of a
rotating mass is considered in detail, namely, the difference in the energy of
a spin-1/2 particle polarized vertically up and down near the surface of a
rotating body is . Here is the latitude and
, where and are, respectively, the angular
momentum and radius of the body. It seems that this relativistic quantum
gravitational effect could be measurable in the foreseeable future.Comment: LaTeX file, no figures, 16 page
Five Kepler target stars that show multiple transiting exoplanet candidates
We present and discuss five candidate exoplanetary systems identified with
the Kepler spacecraft. These five systems show transits from multiple exoplanet
candidates. Should these objects prove to be planetary in nature, then these
five systems open new opportunities for the field of exoplanets and provide new
insights into the formation and dynamical evolution of planetary systems. We
discuss the methods used to identify multiple transiting objects from the
Kepler photometry as well as the false-positive rejection methods that have
been applied to these data. One system shows transits from three distinct
objects while the remaining four systems show transits from two objects. Three
systems have planet candidates that are near mean motion
commensurabilities---two near 2:1 and one just outside 5:2. We discuss the
implications that multitransiting systems have on the distribution of orbital
inclinations in planetary systems, and hence their dynamical histories; as well
as their likely masses and chemical compositions. A Monte Carlo study indicates
that, with additional data, most of these systems should exhibit detectable
transit timing variations (TTV) due to gravitational interactions---though none
are apparent in these data. We also discuss new challenges that arise in TTV
analyses due to the presence of more than two planets in a system.Comment: Accepted to Ap
The ATLAS SCT grounding and shielding concept and implementation
This paper presents a complete description of Virgo, the French-Italian gravitational wave detector. The detector, built at Cascina, near Pisa (Italy), is a very large Michelson interferometer, with 3 km-long arms. In this paper, following a presentation of the physics requirements, leading to the specifications for the construction of the detector, a detailed description of all its different elements is given. These include civil engineering infrastructures, a huge ultra-high vacuum (UHV) chamber (about 6000 cubic metres), all of the optical components, including high quality mirrors and their seismic isolating suspensions, all of the electronics required to control the interferometer and for signal detection. The expected performances of these different elements are given, leading to an overall sensitivity curve as a function of the incoming gravitational wave frequency. This description represents the detector as built and used in the first data-taking runs. Improvements in different parts have been and continue to be performed, leading to better sensitivities. These will be detailed in a forthcoming paper
Controlled Trial of Azathioprine and Cyclosporin to Prevent Anti-LHA Antibodies due to Third-party Transfusion
Abstract. The beneficial effect of elective transfusion on renal allograft survival must be weighed against the risks of sensitisation. We report a randomised controlled trial in which patients in end-stage renal failure who were nonparous and not previously transplanted or transfused, were entered in a transfusion protocol during which one group received no drugs (controls), one received azathioprine, and one received cyclosporin. Each group was given three identical transfusions of leucocyte-enriched fresh blood at 2-3 week intervals. The transfused blood was of known HLA type and donor/recipient pairs were completely mismatched. Sensitisation rates were assessed by T and B cell cross-matches between donor and recipients and by the screening of all sera against lymphocytes from 40 random donors. Fifty-one patients have completed the protocol, 20 in the control group, 12 in the azathioprine group, and 19 in the cyclosporin group. The sensitisation rate in the control group was 30%, occasionally of high titre, and persistent. In the azathioprine group, 25% developed anti-HLA antibodies and reactivity was of high titre and was broadly specific. Sensitisation in the cyclosporin group was 10%, was narrowly specific, reacting with only 10% of a panel, and was transient. There was no difference in graft survival between the groups. We conclude that cyclosporin therapy concurrent with third-party transfusion reduces the incidence, titre, and duration of sensitisation
The trigger system of the NOMAD experiment
The NOMAD trigger system is described in the present paper. It is made up of a largearea plastic scintillator veto system, two trigger scintillator planes inside a 0.4~Tmagnetic field and their associated trigger electronics. Special features of the systemconsist of the use of proximity mesh photomultipliers which allow the trigger scintillators to operate in the magnetic field, and the use of custom-built VME moduleswhich perform the trigger logic decisions, the signal synchronisation and gate generation,event counting and livetime calculations. This paper also includes a description of each of the NOMAD triggers, with their calculated and measured rates, efficiencies and livetimes
A radium assay technique using hydrous titanium oxide adsorbent for the Sudbury Neutrino Observatory
As photodisintegration of deuterons mimics the disintegration of deuterons by
neutrinos, the accurate measurement of the radioactivity from thorium and
uranium decay chains in the heavy water in the Sudbury Neutrino Observatory
(SNO) is essential for the determination of the total solar neutrino flux. A
radium assay technique of the required sensitivity is described that uses
hydrous titanium oxide adsorbent on a filtration membrane together with a
beta-alpha delayed coincidence counting system. For a 200 tonne assay the
detection limit for 232Th is a concentration of 3 x 10^(-16) g Th/g water and
for 238U of 3 x 10^(-16) g U/g water. Results of assays of both the heavy and
light water carried out during the first two years of data collection of SNO
are presented.Comment: 12 pages, 4 figure
Measurement of the rate of nu_e + d --> p + p + e^- interactions produced by 8B solar neutrinos at the Sudbury Neutrino Observatory
Solar neutrinos from the decay of B have been detected at the Sudbury
Neutrino Observatory (SNO) via the charged current (CC) reaction on deuterium
and by the elastic scattering (ES) of electrons. The CC reaction is sensitive
exclusively to nu_e's, while the ES reaction also has a small sensitivity to
nu_mu's and nu_tau's. The flux of nu_e's from ^8B decay measured by the CC
reaction rate is
\phi^CC(nu_e) = 1.75 +/- 0.07 (stat)+0.12/-0.11 (sys.) +/- 0.05(theor) x 10^6
/cm^2 s.
Assuming no flavor transformation, the flux inferred from the ES reaction
rate is
\phi^ES(nu_x) = 2.39+/-0.34 (stat.)+0.16}/-0.14 (sys) x 10^6 /cm^2 s.
Comparison of \phi^CC(nu_e) to the Super-Kamiokande Collaboration's precision
value of \phi^ES(\nu_x) yields a 3.3 sigma difference, providing evidence that
there is a non-electron flavor active neutrino component in the solar flux. The
total flux of active ^8B neutrinos is thus determined to be 5.44 +/-0.99 x
10^6/cm^2 s, in close agreement with the predictions of solar models.Comment: 6 pages (LaTex), 3 figures, submitted to Phys. Rev. Letter
Production properties of K*(892) vector mesons and their spin alignment as measured in the NOMAD experiment
First measurements of K*(892) mesons production properties and their spin
alignment in nu_mu charged current (CC) and neutral current (NC) interactions
are presented. The analysis of the full data sample of the NOMAD experiment is
performed in different kinematic regions. For K*+ and K*- mesons produced in
nu_mu CC interactions and decaying into K0 pi+/- we have found the following
yields per event: (2.6 +/- 0.2 (stat.) +/- 0.2 (syst.))% and (1.6 +/- 0.1
(stat.) +/- 0.1 (syst.))% respectively, while for the K*+ and K*- mesons
produced in nu NC interactions the corresponding yields per event are: (2.5 +/-
0.3 (stat.) +/- 0.3 (syst.))% and (1.0 +/- 0.3 (stat.) +/- 0.2 (syst.))%. The
results obtained for the rho00 parameter, 0.40 +/- 0.06 (stat) +/- 0.03 (syst)
and 0.28 +/- 0.07 (stat) +/- 0.03 (syst) for K*+ and K*- produced in nu_mu CC
interactions, are compared to theoretical predictions tuned on LEP measurements
in e+e- annihilation at the Z0 pole. For K*+ mesons produced in nu NC
interactions the measured rho00 parameter is 0.66 +/- 0.10 (stat) +/- 0.05
(syst).Comment: 20 p
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