14,292 research outputs found
Novel String Banana Template Method of Track Reconstruction for high Multiplicity Events with Significant Multiple Scattering
Novel String Banana Template Method (SBTM) for track reconstruction in high
multiplicity events in non-uniform magnetic field spectrometer with emphasis on
the lowest momenta tracks with significant Multiple Scattering (MS) is
described. Two steps model of track with additional parameter/s which takes
into account MS for this particular track is introduced. SBTM is time efficient
and demonstrates better resolutions than another method equivalent to the Least
Squares method (LSM).Comment: 3 pages, 3 figures, DPF2004 Proceeding, International Journal of
Modern Physics
Flavor violating decays of the Higgs bosons in the THDM-III
We calculate the branching ratios for the decays of neutral Higgs bosons
() into pairs of fermions, including flavor violating
processes, in the context of the General Two Higgs Doublet Model III.Comment: 23 pages, 10 figures, 6 tables. Text clarifying equations and
references added, typos correction
Mid-infrared Variability from the Spitzer Deep Wide-field Survey
We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey to investigate the variability of objects in 8.1 deg^2 of the NOAO Deep Wide Field Survey Boötes field. We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5 ÎŒm bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r > 0.8) and that their joint variance (Ï_(12)) exceeds that for all sources with the same magnitude by 2Ï. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBoötes survey, radio catalogs, 24 ÎŒm selected active galactic nucleus (AGN) candidates, and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24 ÎŒm AGN candidates, and spectroscopically identified AGNs show variability. The exact fractions depend on both the search depth and the selection criteria. For example, 12% of the 1131 known z>1 AGNs in the field and 14%-17% of the known AGNs with well-measured fluxes in all four Infrared Array Camera bands meet our standard selection criteria. The mid-IR AGN variability can be well described by a single power-law structure function with an index of Îł â 0.5 at both 3.6 and 4.5 ÎŒm, and an amplitude of S _0 â 0.1 mag on rest-frame timescales of 2 yr. The variability amplitude is higher for shorter rest-frame wavelengths and lower luminosities
Optical Conductivity in a Two-Band Superconductor: Pb
We demonstrate the effect of bandstructure on the superconducting properties
of Pb by calculating the strong-coupling features in the optical conductivity,
, due to the electron-phonon interaction. The importance of
momentum dependence in the calculation of the properties of superconductors has
previously been raised for MgB. Pb resembles MgB in that it is a two
band superconductor in which the bands' contributions to the Fermi surface have
very different topologies. We calculate by calculating a
memory function which has been recently used to analyze of
BiSrCaCuO. In our calculations the two components of
the Fermi surface are described by parameterizations of de Haas--van Alphen
data. We use a phonon spectrum which is a fit to neutron scattering data. By
including the momentum dependence of the Fermi surface good agreement is found
with the experimentally determined strong-coupling features which can be
described by a broad peak at around 4.5 meV and a narrower higher peak around 8
meV of equal height. The calculated features are found to be dominated by
scattering between states within the third band. By contrast scattering between
states in the second band leads to strong-coupling features in which the height
of the high energy peak is reduced by compared to that of the low
energy peak. This result is similar to that in the conventional isotropic
(momentum independent) treatment of superconductivity. Our results show that it
is important to use realistic models of the bandstructure and phonons, and to
avoid using momentum averaged quantities, in calculations in order to get
quantitatively accurate results
The High Frequency Instrument of Planck: Requirements and Design
The Planck satellite is a project of the European Space Agency based on a wide international collaboration, including United States and Canadian laboratories. It is dedicated to the measurement of the anisotropy of the Cosmic Microwave Background (CMB) with unprecedented sensitivity and angular resolution. The detectors of its High frequency Instrument (HFI) are bolometers cooled down to 100 mK. Their sensitivity will be limited by the photon noise of the CMB itself at low frequencies, and of the instrument background at high frequencies. The requirements on the measurement chain are directly related to the strategy of observation used for the satellite. Due to the scanning on the sky, time features of the measurement chain are directly transformed into angular features in the sky maps. This impacts the bolometer design as well as other elements: For example, the cooling system must present outstanding temperature stability, and the amplification chain must show, down to very low frequencies, a flat noise spectrum
Use of High Sensitivity Bolometers for Astronomy: Planck High Frequency Instrument
The Planck satellite is dedicated to the measurement of the anisotropy of the Cosmic Microwave Background (CMB) with unprecedented sensitivity and angular resolution. It is a
project of the European Space Agency based on a wide international collaboration, including United States and Canadian laboratories. The detectors of its High Frequency Instrument (HFI) are bolometers cooled down to 100 mK. Their sensitivity will be limited by the photon noise of
the CMB itself at low frequencies, and of the instrument background at high frequencies. The requirements on the measurement chain are directly related to the strategy of observation used for the satellite. This impacts the bolometer design as well as other elements: The cooling system must present outstanding temperature stability, and the amplification chain must show a flat noise spectrum down to very low frequencies
Deep Herschel view of obscured star formation in the Bullet cluster
We use deep, five band (100â500 ÎŒm) data from the Herschel Lensing Survey (HLS) to fully constrain the obscured star formation rate, SFR_(FIR), of galaxies in the Bullet cluster (z = 0.296), and a smaller background system (z = 0.35) in the same field. Herschel detects 23 Bullet cluster members with a total SFRFIR = 144±14 M_â yr^(-1). On average, the background system contains brighter far-infrared (FIR) galaxies, with ~50% higher SFRFIR (21 galaxies; 207 ± 9 M_â yr^(-1)). SFRs extrapolated from 24 ÎŒm flux via recent templates (SFR_(24 ”m)) agree well with SFRFIR for ~60% of the cluster galaxies. In the remaining ~40%, SFR24 ”m underestimates SFR_(FIR) due to a significant excess in observed S_(100)/S_(24) (rest frame S_(75)/S_(18)) compared to templates of the same FIR luminosity
Neutrinos and Future Concordance Cosmologies
We review the free parameters in the concordance cosmology, and those which
might be added to this set as the quality of astrophysical data improves. Most
concordance parameters encode information about otherwise unexplored aspects of
high energy physics, up to the GUT scale via the "inflationary sector," and
possibly even the Planck scale in the case of dark energy. We explain how
neutrino properties may be constrained by future astrophysical measurements.
Conversely, future neutrino physics experiments which directly measure these
parameters will remove uncertainty from fits to astrophysical data, and improve
our ability to determine the global properties of our universe.Comment: Proceedings of paper given at Neutrino 2008 meeting (by RE
Effects of Intravenous Aspirin on Prostaglandin Synthesis and Kidney Function in Intensive Care Patients
The effects of intravenous acetylsalicylic acid (1.0 g bolus) on renal function and prostaglandin synthesis were evaluated in a prospective, controlled study in eight patients in an intensive care unit. Four of these patients had congestive heart failure. Administration of acetylsalicylic acid caused significant antidiuresis (â56%), antinatriuresis (â82%), renin suppression (â26%) and decreased GFR (â41%). All of these changes were completely reversible within 1-2 hours and tended to be more pronounced in the patients with congestive heart failure. Urinary excretion of prostaglandin E was depressed profoundly (â93%) and did not return to more than 45% of control 6 h after the administration of acetylsalicylic acid. We conclude that intravenous acetylsalicylic acid affects kidney function in a manner similar to other prostaglandin synthesis inhibitors. Its effects are, however, short-lived. The inhibition of urinary PGE2 excretion outlasts GFR depression, antidiuresis, antinatriuresis and renin suppression by several hour
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