459 research outputs found
Italian Magnetic Network and magnetic reference fields at 2010.0
The Istituto Nazionale di Geofisica e Vulcanologia (INGV) has systematically
undertaken the task of making measurements of the Earth's magnetic field in Italy. By tradition and because of the elongated geometric shape of our peninsula and islands, in Italy, a grid of more than 110
points, called the first order repeat stations, with an average spacing around 55-60 km, is in operation. Over this grid the measurements are repeated regularly, every 5 years. A survey of 131 repeat stations of the Italian Magnetic Network (including 2 observatories, 11 stations in Albania, 3 stations in Corsica and 1 in Malta) was carried out between 2009 and
2010 with the main purpose of updating our magnetic cartography. We describe the characteristics of magnetic first and second order networks,
the magnetic measurements and the data reduction procedure. In agreement
with the recommendations of MagNetE Committee, we report new repeat station data measured and reduced at 2010.0. An analytical expression, a second order polynomial, in latitude and longitude for the field elements, was determined, and coefficients for 2010.0 and average secular
variation over the period 2005-2010, were obtained. The new maps for Italy, for D, F, H and Z at the epoch 2010.0, are shown. A selection of stations from the Italian Magnetic Network, based on their low values of anomaly with respect to a 'normal' field, is also proposed for future surveys
A simple method for the determination of lipid composition of human bile
The Entero-Test, a device for easy sampling of gastrointestinal contents, including bile, has been used for determination of biliary lipid composition. The device consists of a weighted gelatin capsule containing 140 cm of a highly absorbent nylon line. The capsule is swallowed while one end of the string is taped to the face. After 3.5 h, when the line has reached the duodenum, gallbladder contraction is stimulated by intramuscular administration of ceruletide. The line is pulled out, and the last 15 cm are eluted four times in methanol. Total bile acids (by 3 alpha-hydroxysteroid-dehydrogenase assay), individual bile acids (by high performance liquid chromatography), phospholipids (by assay of lipid-soluble phosphorus), and cholesterol (by gas-liquid chromatography) are determined in the eluate. Tests in vitro demonstrated no preferential binding and a good recovery of biliary lipids from the thread. Similar values of biliary cholesterol saturation were obtained by means of duodenal intubation and of the Entero-Test in a series of 12 subjects (r = 0.952). In 5 subjects, individual bile acids were also measured and were found to be similar with both techniques (r = 0.948). When the test was repeated over 3 days in a series of 7 subjects, biliary cholesterol saturation was found to be remarkably reproducible (CV = 7.6%). Thus, the Entero-Test is a convenient technique for the determination of biliary lipid composition, which can be particularly useful in longitudinal studies
Serum 25-hydroxyvitamin D3 concentrations and prevalence of cardiovascular disease among type 2 diabetic patients.
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Precise measurement of the top quark mass in the dilepton channel at D0
We measure the top quark mass (mt) in ppbar collisions at a center of mass
energy of 1.96 TeV using dilepton ttbar->W+bW-bbar->l+nubl-nubarbbar events,
where l denotes an electron, a muon, or a tau that decays leptonically. The
data correspond to an integrated luminosity of 5.4 fb-1 collected with the D0
detector at the Fermilab Tevatron Collider. We obtain mt = 174.0 +- 1.8(stat)
+- 2.4(syst) GeV, which is in agreement with the current world average mt =
173.3 +- 1.1 GeV. This is currently the most precise measurement of mt in the
dilepton channel.Comment: 7 pages, 4 figure
Journal Staff
We present the first measurements of the differential cross section d sigma/dp(T)(gamma) for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapidities vertical bar y(gamma)vertical bar < 1.0 and transverse momenta 30 < p(T)(gamma) < 200 GeV. The b-quark jets are required to have p(T)(jet) > 15 GeVand vertical bar y(jet)vertical bar < 1.5. The ratio of differential production cross sections for gamma + 2 b-jets to gamma + b-jet as a function of p(T)(gamma) is also presented. The results are based on the proton-antiproton collision data at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next- to- leading order perturbative QCD calculations as well as predictions based on the k(T)- factorization approach and those from the sherpa and pythia Monte Carlo event generators
Direct measurement of the mass difference between top and antitop quarks
We present a direct measurement of the mass difference between top and
antitop quarks (dm) in lepton+jets top-antitop final states using the "matrix
element" method. The purity of the lepton+jets sample is enhanced for
top-antitop events by identifying at least one of the jet as originating from a
b quark. The analyzed data correspond to 3.6 fb-1 of proton-antiproton
collisions at 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron
Collider. The combination of the e+jets and mu+jets channels yields dm = 0.8
+/- 1.8 (stat) +/- 0.5 (syst) GeV, which is in agreement with the standard
model expectation of no mass difference.Comment: submitted to Phys. Rev.
Measurement of the top quark pair production cross section in the lepton+jets channel in proton-antiproton collisions at =1.96 TeV
We present a measurement of the inclusive top quark pair production cross
section in \ppbar collisions at (\sqrt{s}=1.96) TeV utilizing data
corresponding to an integrated luminosity of \lumi\ collected with the D0
detector at the Fermilab Tevatron Collider. We consider final states containing
one high- isolated electron or muon and at least two jets, and we
perform three analyses: one exploiting specific kinematic features of \ttbar
events, the second using -jet identification, and the third using both
techniques to separate \ttbar\ signal from background. In the third case, we
determine simultaneously the cross section and the ratio of the
production rates of +heavy flavor jets and +light flavor jets, which
reduces the impact of the systematic uncertainties related to the background
estimation. Assuming a top quark mass of 172.5 GeV, we obtain
pb. This result agrees with
predictions of the standard model.Comment: 19 pages, 6 figures, submitted to Phys. Rev.
Search for first generation leptoquark pair production in the electron + missing energy + jets final state
We present a search for the pair production of first generation scalar
leptoquarks (LQ) in data corresponding to an integrated luminosity of 5.4
fb collected with the D0 detector at the Fermilab Tevatron Collider in
ppbar collisions at TeV. In the channel , where q, q' are u or d quarks, no significant excess
of data over background is observed, and we set a 95% C.L. lower limit of 326
GeV on the leptoquark mass, assuming equal probabilities of leptoquark decays
to eq and .Comment: 7 pages, 6 figures, submitted to PRD-R
Search for the standard model and a fermiophobic Higgs boson in diphoton final states
We present a search for the standard model Higgs boson and a fermiophobic
Higgs boson in the diphoton final states based on 8.2 fb-1 of ppbar collisions
collected with the D0 detector at the Fermilab Tevatron Collider. No excess of
data above background predictions is observed and upper limits at the 95% C.L.
on the cross section multiplied by the branching fraction are set which are the
most restrictive to date. A fermiophobic Higgs boson with a mass below 112.9
GeV is excluded at the 95% C.L.Comment: 12 pages, 21 figures, submitted to PR
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