12,768 research outputs found
Electroweak Tests at Beta-beams
We explore the possibility of measuring the Weinberg angle from
(anti)neutrino-electron scattering using low energy beta beams, a method that
produces single flavour neutrino beams from the beta-decay of boosted
radioactive ions. We study how the sensitivity of a possible measurement
depends on the intensity of the ion beam and on a combination of different
Lorentz boosts of the ions.Comment: 10 pages, 6 figure
WHAT IS THE LENGTH OF A SNAKE?
The way that herpetologists have traditionally measuredlive snakes is by stretching them on a ruler andrecording the total length (TL). However, due to the thinconstitution of the snake, the large number of intervertebraljoints, and slim muscular mass of most snakes,it is easier to stretch a snake than it is to stretch anyother vertebrate. The result of this is that the length ofa snake recorded is infl uenced by how much the animalis stretched. Stretching it as much as possible is perhapsa precise way to measure the length of the specimenbut it might not correspond to the actual length ofa live animal. Furthermore, it may seriously injure a livesnake. Another method involves placing the snake in aclear plexiglass box and pressing it with a soft materialsuch as rubber foam against a clear surface. Measuringthe length of the snake may be done by outlining itsbody with a string (Fitch 1987; Frye 1991). However, thismethod is restricted to small animals that can be placedin a box, and in addition, no indications of accuracy of thetechnique are given. Measuring the snakes with a fl exibletape has also been reported (Blouin-Demers 2003)but when dealing with a large animals the way the tapeis positioned can produce great variance on the fi nal outcome.In this contribution we revise alternative ways tomeasuring a snake and propose a method that offers repeatableresults. We further analyze the precision of thismethod by using a sample of measurements taken fromwild populations of green anacondas (Eunectes murinus)with a large range of sizes
New coupled quintessence cosmology
A component of dark energy has been recently proposed to explain the current
acceleration of the Universe. Unless some unknown symmetry in Nature prevents
or suppresses it, such a field may interact with the pressureless component of
dark matter, giving rise to the so-called models of coupled quintessence. In
this paper we propose a new cosmological scenario where radiation and baryons
are conserved, while the dark energy component is decaying into cold dark
matter (CDM). The dilution of CDM particles, attenuated with respect to the
usual scaling due to the interacting process, is characterized by a
positive parameter , whereas the dark energy satisfies the equation
of state (). We carry out a joint statistical
analysis involving recent observations from type Ia supernovae, baryon acoustic
oscillation peak, and Cosmic Microwave Background shift parameter to check the
observational viability of the coupled quintessence scenario here proposed.Comment: 7 pages, 7 figures. Minor corrections to match published versio
Low-energy neutrinos at off-axis from a standard beta-beam
We discuss a scenario to extract up to 150 MeV neutrinos at a standard
beta-beam facility using one and two detectors off-axis. In particular we show
that the high-energy component of the neutrino fluxes can be subtracted through
a specific combination of the response of two off-axis detectors. A systematic
analysis of the neutrino fluxes using different detector geometries is
presented, as well as a comparison with the expected fluxes at a low-energy
beta-beam facility. The presented option could offer an alternative way to
perform low-energy neutrino experiments.Comment: 9 pages, 6 figure
Is the transition redshift a new cosmological number?
Observations from Supernovae Type Ia (SNe Ia) provided strong evidence for an
expanding accelerating Universe at intermediate redshifts. This means that the
Universe underwent a transition from deceleration to acceleration phases at a
transition redshift of the order unity whose value in principle depends
on the cosmology as well as on the assumed gravitational theory. Since
cosmological accelerating models endowed with a transition redshift are
extremely degenerated, in principle, it is interesting to know whether the
value of itself can be observationally used as a new cosmic
discriminator. After a brief discussion of the potential dynamic role played by
the transition redshift, it is argued that future observations combining SNe
Ia, the line-of-sight (or "radial") baryon acoustic oscillations, the
differential age of galaxies, as well as the redshift drift of the spectral
lines may tightly constrain , thereby helping to narrow the parameter
space for the most realistic models describing the accelerating Universe.Comment: 12 pages, 5 figures. Some discussions about how to estimate the
transition redshift have been added. New data by Planck and H(z) data have
been mentioned. New references have been adde
Acoustic oceanographic buoy (version 1)
SiPLAB Report 06/05, FCT, University of Algarve,2005.One of the known impairements in the application of ocean acoustic tomography in operational scenarios has been the size, weight and difficulty of operation of actual ocean going equipment, such as hydrophone arrays and acoustic sources. The Acoustic Oceanographic Buoy - AOB is meant to be, at its final stage, an easy to deploy and easy to maintain autonomous vertical array that puts together in a single system acoustic and non-acoustic sensors, self-storing of geotime and GPS referred data, on the buoy preprocessing capabilities and network seamless integrability and data online transfer via a wireless lan high speed link. These capabilities make the AOB a versatile system for a variety of applications such as ocean tomography, underwater communications, rapid environmental assessment (REA), passive and multistatic sonar and underwater target tracking. The AOB version 1 described in this report was developed between 2003 and 2004 and tested at sea during the MREA’03 and MREA’04 sea trials
INTIFANTE'00 sea trial data report - Events I,II and III
Rep 02/01 - SiPLAB
4/May/2001This report describes the data acquired during Events I,
II and III of the INTIFANTE'00 sea trial, that took
place from 9 - 29 October 2000, o the Tr oia
Peninsula, near Set ubal, Portugal
Acoustic Oceanographic Buoy Test during the MREA’03 Sea Trial
Rep 04/03 - SiPLAB
10/Nov/2003Environmental inversion of acoustic signals for bottom and water column properties is
being proposed in the literature as an interesting concept for complementing direct hydrographic
and oceanographic measurements for Rapid Environmental Assessment (REA).
The acoustic contribution to REA can be cast as the result of the inversion of ocean
acoustic properties to be assimilated into ocean circulation models specifically tailored
and calibrated to the scale of the area under observation. Traditional ocean tomography
systems and methods for their requirements of long and well populated receiving
arrays and precise knowledge of the source/receiver geometries are not well adapted to
operational Acoustic REA (AREA).
An innovative concept that responds to the operational requirements of AREA is being
proposed under a Saclantcen JRP jointly submitted by the the Universit´e Libre de
Bruxelles (ULB), SiPLAB/CINTAL at University of Algarve, the Instituto Hidrogr´afico
(IH) and the Royal Netherlands Naval College (RNLNC) and approved by Saclantcen
in 2003 under the 2004 SPOW. That concept includes the development of water column
and geo-acoustic inversion methods being able to retrieve environmental true properties
from signals received on a drifting network of Acoustic-Oceanographic Buoys (AOB). A
prototype of an AOB and a preliminary version of the inversion code, was tested at sea
during the Maritime Rapid Environment Assessment’2003 sea trial (MREA’03) and is
described in this report together with the results obtained.This report presents the AOB system and the results obtained during its testing in the
MREA’03 sea trial. The MREA’03 sea trial took place off the Italian coast, near Elba I.
in the period 26 May - 27 June 2003.
The authors of this report would like to thank: the SACLANT Undersea Research Centre for the opportunity for participating in
the sea trial
• the scientist in charge Dr. Emanuel Coelho; the collaboration of Saclantcen personnel; the master and crew of the R/V Alliance; the contribution of Prof. J.-P. Hermand from ULB for the discussions and pictures
shown in this report
Common Variable Immunodeficiency Associated with Hepatosplenic T-Cell Lymphoma Mimicking Juvenile Systemic Lupus Erythematosus
Common variable immunodeficiency (CVID) is a heterogeneous disorder with susceptibility to infections, autoimmune manifestations, and cancer. To our knowledge, CIVD with T-cell lymphoma mimicking juvenile systemic lupus erythematosus (JSLE) was not described in the literature, and one case was reported herein. An 8-year-old female was admitted in our Pediatric Immunology Unit with a clinical history of hypogammaglobulinemia, recurrent upper respiratory infections, and pneumonias. She had a marked decrease of three serum immunoglobulin isotypes, and the diagnosis of CVID was established. At the age of 17 years, she presented with oral ulceration, nonerosive arthritis, nephritis, serositis, cytopenia, positive antiphospholipid antibodies, and positive antinuclear antibody fulfilling the American College of Rheumatology (ACR) criteria for SLE. She was treated with intravenous methylprednisolone for three consecutive days, and intravenous immunoglobulin, and maintenance therapy of chloroquine, azathioprine and prednisone 40 mg/day. Two months later, she died of septic shock secondary to acute pneumonia. The necropsy showed hepatosplenic T-cell lymphoma with diffuse involvement of bone marrow, spleen, liver, and lungs. The lymphoma cells were positive for CD3 immunostaining and negative for CD20 and lysozyme. In conclusion, the association of CVID and hepatosplenic T-cell lymphoma may simulate JSLE diagnosis
- …