3,475 research outputs found
Temperature dependent characterization of optical fibres for distributed temperature sensing in hot geothermal wells
This study was performed in order to select a proper fibre for the
application of a distributed temperature sensing system within a hot geothermal
well in Iceland. Commercially available high temperature graded index fibres
have been tested under in-situ temperature conditions. Experiments have been
performed with four different polyimide coated fibres, a fibre with an aluminum
coating and a fibre with a gold coating. To select a fibre, the relationship
between attenuation, temperature, and time has been analyzed together with SEM
micrographs. On the basis of these experiments, polyimide fibres have been
chosen for utilisation. Further tests in ambient and inert atmosphere have been
conducted with two polyimide coated fibres to set an operating temperature
limit for these fibres. SEM micrographs, together with coating colour changes
have been used to characterize the high temperature performance of the fibres.
A novel cable design has been developed, a deployment strategy has been worked
out and a suitable well for deployment has been selected.Comment: PACS: 42.81.Pa, 93.85.Fg, 47.80.Fg, 91.35.Dc, 07.20.Dt, 07.60.V
Stochastic background from extra-galactic double neutron stars
We present Monte Carlo simulations of the extra galactic population of
inspiralling double neutron stars, and estimate its contribution to the
astrophysical gravitational wave background, in the frequency range of ground
based interferometers, corresponding to the last thousand seconds before the
last stable orbit when more than 96 percent of the signal is released. We show
that sources at redshift z>0.5 contribute to a truly continuous background
which may be detected by correlating third generation interferometers.Comment: 13 pages, 7 figures - proceeding of a talk given at the 11th GWDAW,
to appear in CQ
The Coulomb law in the pure gauge U(1) theory on a lattice
We study the heavy charge potential in the Coulomb phase of pure gauge
compact U(1) theory on the lattice. We calculate the static potential
from Wilson loops on a lattice and compare
with the predictions of lattice perturbation theory. We investigate finite size
effects and, in particular, the importance of non-Coulomb contributions to the
potential. We also comment on the existence of a maximal coupling in the
Coulomb phase of pure gauge U(1) theory.Comment: 14 pages. LaTeX file and 3 postscript figure
Improving the sensitivity of future GW observatories in the 1-10 Hz band: Newtonian and seismic noise
The next generation gravitational wave interferometric detectors will likely be underground detectors to extend the GW detection frequency band to frequencies below the Newtonian noise limit. Newtonian noise originates from the continuous motion of the Earth’s crust driven by human activity, tidal stresses and seismic motion, and from mass density fluctuations in the atmosphere. It is calculated that on Earth’s surface, on a typical day, it will exceed the expected GW signals at frequencies below 10 Hz. The noise will decrease underground by an unknown amount. It is
important to investigate and to quantify this expected reduction and its effect on the sensitivity of future detectors, to plan for further improvement strategies. We report about some of these aspects. Analytical models can be used in the simplest scenarios to get a better qualitative and semi-quantitative understanding. As more complete modeling can be done numerically, we will discuss also some results obtained with a finite-element-based modeling tool. The method is verified by comparing its results with the results of analytic calculations for surface detectors. A key point about noise models is their initial parameters and conditions, which require detailed information about seismic motion in a real scenario. We will describe an effort to characterize the seismic activity at the Homestake mine which is currently in progress. This activity is specifically aimed to provide informations and to explore the site as a possible candidate for an underground observatory. Although the only compelling reason to put the interferometer underground is to reduce the Newtonian noise, we expect that the more stable underground environment will have a more general positive impact on the sensitivity.We will end this report with some considerations about seismic and suspension noise
HOT WIRE METHOD FOR THE THERMAL CHARACTERIZATION OF MATERIALS: INVERSE PROBLEM APPLICATION
An experimental set-up of the hot wire method is presented. The present design
allows the measurement of the temperatures at two different points on the heating
wire with an acquisition system that performs measurements at a frequency of 1kHz
with a 12 bit numerical converter. An analytical solution for the direct model for the
time dependent problem of heat transfer is employed. It is based on the quadrupole
method which basically consists in a transfer matrix approach which is possible
through the use of Laplace transforms. It extends the electrical analogy of heat
transfer problems using the notion of impedance, and allows to take into account the
thermal behavior of the wire, as well as contact resistance and heat loss effects in a
very simple straightforward way. In the identification process carried on the
temperature experimental data relies on a sampling of the data that is
logarithmically spaced in time. The initial guesses for the thermal conductivity
values are obtained applying the well known and ideal model of the linear
temperature evolution versus the logarithm of the time. These values are used to
start up the algorithms that are applied in the minimization of the cost functional of
the squared residues between measured and calculated temperatures. The precision
of the estimates is assessed with the calculated confidence bounds obtained by the
variance-covariance matrix at the converged solution
Double Penguins and the Contribution of Vector Meson--like States to the Decays
Using perturbative QCD, the contribution at the leading twist, leading
level, of charm and up quark loops to the decays and is presented. In the case of , the relative importance of these contributions depend
upon the unknown CKM matrix elements and .
Assuming that the ratio is bounded
between as is suggested by the Particle Data Group, the
error in extracting by these decays is estimated.Comment: 4 double column pages, revtex, 3 figures attached, 2 figures added
indicating less optimism concerning the accuracy at which
can be extracted: to appear in PR
Symptom burden among patients with Renal Cell Carcinoma (RCC): content for a symptom index
© 2007 Harding et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Subnuclear localization, rates and effectiveness of UVC-induced unscheduled DNA synthesis visualized by fluorescence widefield, confocal and super-resolution microscopy
Unscheduled DNA synthesis (UDS) is the final stage of the process of repair of DNA lesions induced by UVC. We detected UDS using a DNA precursor, 5-ethynyl-2′-deoxyuridine (EdU). Using wide-field, confocal and super-resolution fluorescence microscopy and normal human fibroblasts, derived from healthy subjects, we demonstrate that the sub-nuclear pattern of UDS detected via incorporation of EdU is different from that when BrdU is used as DNA precursor. EdU incorporation occurs evenly throughout chromatin, as opposed to just a few small and large repair foci detected by BrdU. We attribute this difference to the fact that BrdU antibody is of much larger size than EdU, and its accessibility to the incorporated precursor requires the presence of denatured sections of DNA. It appears that under the standard conditions of immunocytochemical detection of BrdU only fragments of DNA of various length are being denatured. We argue that, compared with BrdU, the UDS pattern visualized by EdU constitutes a more faithful representation of sub-nuclear distribution of the final stage of nucleotide excision repair induced by UVC. Using the optimized integrated EdU detection procedure we also measured the relative amount of the DNA precursor incorporated by cells during UDS following exposure to various doses of UVC. Also described is the high degree of heterogeneity in terms of the UVC-induced EdU incorporation per cell, presumably reflecting various DNA repair efficiencies or differences in the level of endogenous dT competing with EdU within a population of normal human fibroblasts
Exact Calculation of , \
We present an exact calculation of the Wilson coefficients
associated with the dipole moment operators. We also give an estimate of the
branching ratio for . We find that higher dimensional
effects are under control within for .Comment: 12 pages (plain TeX), 2 postscript figures available upon request.
UM-TH-93-20 , IP-ASTP-29-9
- …