724 research outputs found
HISTORICAL AND ARCHAEOSEISMIC STUDIES IN THE POLLINO AREA
Section 1. Reappraisal of the January 8, 1693 Pollino earthquake Section 2. Archaeoseismic field survey Section 3. Investigation of damaged speleothem
Comparative assessment of the food purchase program and the national school feeding program's impact in Ubá, Minas Gerais, Brazil
Role of interventional radiology in the management of complications after pancreatic surgery: a pictorial review
Pancreatic resections are surgical procedures associated with high incidence of complications, with relevant morbidity and mortality even at high volume centres. A multidisciplinary approach is essential in the management of these events and interventional radiology plays a crucial role in the treatment of patients developing post-surgical complications. This paper offers an overview on the interventional radiological procedures that can be performed to treat different type of complications after pancreatic resection. Procedures such as percutaneous drainage of fluid collections, percutaneous transhepatic biliary procedures, arterial embolisation, venous interventions and fistula embolisation are viable treatment options, with fewer complications compared with re-look surgery, shorter hospital stay and faster recovery. A selection of cases of complications following pancreatic surgery managed with interventional radiological procedure are presented and discussed. Teaching Points \u2022 Interventional radiology is crucial to treat complications after pancreatic surgery \u2022 Percutaneous drainage of collections can be performed under ultrasound or computed tomography guidance \u2022 Percutaneous biliary procedures can be used to treat biliary complications \u2022 Venous procedures can be performed effectively through transhepatic or transjugular access \u2022 Fistulas can be treated effectively by percutaneous embolisation
Phonon-induced dephasing of localized optical excitations
The dynamics of strongly localized optical excitations in semiconductors is studied including electron-phonon interaction. The coupled microscopic equations of motion for the interband polarization and the carrier distribution functions contain coherent and incoherent contributions. While the coherent part is solved through direct numerical integration, the incoherent one is treated by means of a generalized Monte Carlo simulation. The approach is illustrated for a simple model system. The temperature and excitation energy dependence of the optical dephasing rate is analyzed and the results are compared to those of alternative approaches
Neutrino Masses, Mixing and New Physics Effects
We introduce a parametrization of the effects of radiative corrections from
new physics on the charged lepton and neutrino mass matrices, studying how
several relevant quantities describing the pattern of neutrino masses and
mixing are affected by these corrections. We find that the ratio omega = sin
theta / tan theta_atm is remarkably stable, even when relatively large
corrections are added to the original mass matrices. It is also found that if
the lightest neutrino has a mass around 0.3 eV, the pattern of masses and
mixings is considerably more stable under perturbations than for a lighter or
heavier spectrum. We explore the consequences of perturbations on some flavor
relations given in the literature. In addition, for a quasi-degenerate neutrino
spectrum it is shown that: (i) starting from a bi-maximal mixing scenario, the
corrections to the mass matrices keep tan theta_atm very close to unity while
they can lower tan theta_sol to its measured value; (ii) beginning from a
scenario with a vanishing Dirac phase, corrections can induce a Dirac phase
large enough to yield CP violation observable in neutrino oscillations.Comment: 14 pages, 21 figures. Uses RevTeX4. Added several comments and
references. Final version to appear in PR
The ARGO-YBJ Experiment Progresses and Future Extension
Gamma ray source detection above 30TeV is an encouraging approach for finding
galactic cosmic ray origins. All sky survey for gamma ray sources using wide
field of view detector is essential for population accumulation for various
types of sources above 100GeV. To target the goals, the ARGO-YBJ experiment has
been established. Significant progresses have been made in the experiment. A
large air shower detector array in an area of 1km2 is proposed to boost the
sensitivity. Hybrid detection with multi-techniques will allow a good
discrimination between different types of primary particles, including photons
and protons, thus enable an energy spectrum measurement for individual specie.
Fluorescence light detector array will extend the spectrum measurement above
100PeV where the second knee is located. An energy scale determined by balloon
experiments at 10TeV will be propagated to ultra high energy cosmic ray
experiments
High Altitude test of RPCs for the ARGO-YBJ experiment
A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory
(Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive
Air Showers was studied. Efficiency and time resolution measurements at the
pressure and temperature conditions typical of high mountain laboratories, are
reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met
A measurement of the tau mass and the first CPT test with tau leptons
We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV
using tau pairs from Z0 decays. To test CPT invariance we compare the masses of
the positively and negatively charged tau leptons. The relative mass difference
is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.
Measurement of the B0 Lifetime and Oscillation Frequency using B0->D*+l-v decays
The lifetime and oscillation frequency of the B0 meson has been measured
using B0->D*+l-v decays recorded on the Z0 peak with the OPAL detector at LEP.
The D*+ -> D0pi+ decays were reconstructed using an inclusive technique and the
production flavour of the B0 mesons was determined using a combination of tags
from the rest of the event. The results t_B0 = 1.541 +- 0.028 +- 0.023 ps, Dm_d
= 0.497 +- 0.024 +- 0.025 ps-1 were obtained, where in each case the first
error is statistical and the second systematic.Comment: 17 pages, 4 figures, submitted to Phys. Lett.
First Measurement of Z/gamma* Production in Compton Scattering of Quasi-real Photons
We report the first observation of Z/gamma* production in Compton scattering
of quasi-real photons. This is a subprocess of the reaction e+e- to
e+e-Z/gamma*, where one of the final state electrons is undetected.
Approximately 55 pb-1 of data collected in the year 1997 at an e+e-
centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been
analysed. The Z/gamma* from Compton scattering has been detected in the
hadronic decay channel. Within well defined kinematic bounds, we measure the
product of cross-section and Z/gamma* branching ratio to hadrons to be
(0.9+-0.3+-0.1) pb for events with a hadronic mass larger than 60 GeV,
dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60
GeV, dominated by (e)egamma* production, this product is found to be
(4.1+-1.6+-0.6) pb. Our results agree with the predictions of two Monte Carlo
event generators, grc4f and PYTHIA.Comment: 18 pages, LaTeX, 5 eps figures included, submitted to Physics Letters
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