8,500 research outputs found
Underground Neutrino Detectors for Particle and Astroparticle Science: the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER)
The current focus of the CERN program is the Large Hadron Collider (LHC),
however, CERN is engaged in long baseline neutrino physics with the CNGS
project and supports T2K as recognized CERN RE13, and for good reasons: a
number of observed phenomena in high-energy physics and cosmology lack their
resolution within the Standard Model of particle physics; these puzzles include
the origin of neutrino masses, CP-violation in the leptonic sector, and baryon
asymmetry of the Universe. They will only partially be addressed at LHC. A
positive measurement of would certainly give a
tremendous boost to neutrino physics by opening the possibility to study CP
violation in the lepton sector and the determination of the neutrino mass
hierarchy with upgraded conventional super-beams. These experiments (so called
``Phase II'') require, in addition to an upgraded beam power, next generation
very massive neutrino detectors with excellent energy resolution and high
detection efficiency in a wide neutrino energy range, to cover 1st and 2nd
oscillation maxima, and excellent particle identification and
background suppression. Two generations of large water Cherenkov
detectors at Kamioka (Kamiokande and Super-Kamiokande) have been extremely
successful. And there are good reasons to consider a third generation water
Cherenkov detector with an order of magnitude larger mass than Super-Kamiokande
for both non-accelerator (proton decay, supernovae, ...) and accelerator-based
physics. On the other hand, a very massive underground liquid Argon detector of
about 100 kton could represent a credible alternative for the precision
measurements of ``Phase II'' and aim at significantly new results in neutrino
astroparticle and non-accelerator-based particle physics (e.g. proton decay).Comment: 31 pages, 14 figure
Superconformal mechanics, black holes, and non-linear realizations
The OSp(2|2)-invariant planar dynamics of a D=4 superparticle near the
horizon of a large mass extreme black hole is described by an N=2
superconformal mechanics, with the SO(2) charge being the superparticle's
angular momentum. The {\it non-manifest} superconformal invariance of the
superpotential term is shown to lead to a shift in the SO(2) charge by the
value of its coefficient, which we identify as the orbital angular momentum.
The full SU(1,1|2)-invariant dynamics is found from an extension to N=4
superconformal mechanics.Comment: 19 pages, plain latex file. Slightly shortened version, two
references adde
Recent Advances in Chromospheric and Coronal Polarization Diagnostics
I review some recent advances in methods to diagnose polarized radiation with
which we may hope to explore the magnetism of the solar chromosphere and
corona. These methods are based on the remarkable signatures that the
radiatively induced quantum coherences produce in the emergent spectral line
polarization and on the joint action of the Hanle and Zeeman effects. Some
applications to spicules, prominences, active region filaments, emerging flux
regions and the quiet chromosphere are discussed.Comment: Review paper to appear in "Magnetic Coupling between the Interior and
the Atmosphere of the Sun", eds. S. S. Hasan and R. J. Rutten, Astrophysics
and Space Science Proceedings, Springer-Verlag, 200
Fluctuations in the electron system of a superconductor exposed to a photon flux
We report on fluctuations in the electron system, Cooper pairs and
quasiparticles, of a superconducting aluminium film. The superconductor is
exposed to pair-breaking photons (1.54 THz), which are coupled through an
antenna. The change in the complex conductivity of the superconductor upon a
change in the quasiparticle number is read out by a microwave resonator. A
large range in radiation power can be chosen by carefully filtering the
radiation from a blackbody source. We identify two regimes. At high radiation
power, fluctuations in the electron system caused by the random arrival rate of
the photons are resolved, giving a straightforward measure of the optical
efficiency (48%). At low radiation power fluctuations are dominated by excess
quasiparticles, the number of which is measured through their recombination
lifetime
Population of human ventricular cell models calibrated with in vivo measurements unravels ionic mechanisms of cardiac alternans
Cardiac alternansis an important risk factor in cardiac physiology, and is related to the initiation of many pathophysiological conditions. However, the mechanisms underlying the generation of alternans remain unclear. In this study, we used a population of computational human ventricle models based onthe O’Hara model [1] to explore the effect of 11 key factors experimentally reported to be related to alternans. In vivo experimental datasets coming from patients undergoing cardiac surgery were used in the calibration of our in silico population of models. The calibrated models in the population were divided into two groups (Normal and Alternans) depending on alternans occurrence. Our results showed that there were significant differences in the following 5 ionic currents between the two groups: fast sodium current, sodium calcium exchanger current, sodium potassium pump current, sarcoplasmic reticulum (SR) calcium release flux and SR calcium reuptake flux. Further analysis indicated that fast sodium current and SR calcium uptake were the two most significant currents that contributed to voltage and calcium alternans generation, respectively
Biological parameters and parasitism capacity of Telenomus remus Nixon (Hymenoptera: Platygastridae) reared on natural and factitious hosts for successive generations.
Factitious hosts are largely used in parasitoid production. However, changes in parasitism capacity may happen when hosts are switched. Therefore, the ability of a parasitoid species to be reared on factitious host and still keep high level of parasitism on the natural target pest after successive rearing can determine parasitoid quality and must be investigated. Thus, we evaluated Telenomus remus parasitism on Corcyra cephalonica eggs compared with its natural host, Spodoptera frugiperda eggs, for different generations. After being reared on C. cephalonica, T. remus parasitism on S. frugiperda was evaluated to measure different T. remus biological parameters and parasitism capacity (parasitoid quality). Gradual increase in C. cephalonica eggs parasitized was observed over the generations, stabilizing on generation F7. The number of parasitized C. cephalonica eggs was similar among generations (from generation F7 to F19). Taking the lifetime parasitism into consideration, parasitism capacity is similar from T. remus reared on S. frugiperda eggs from those reared on C. cephalonica eggs (generation F19). When laboratory-produced T. remus on C. cephalonica eggs was exposed to the natural host, parasitism was higher on F5 generation and stable from generations F5 to F19. Therefore,parasitoids did not lose their ability to parasitize eggs of natural host assuring good quality of the laboratory-produced parasitoid using C. cephalonica eggs as factitious host
Matter profile effect in neutrino factory
We point out that the matter profile effect --- the effect of matter density
fluctuation on the baseline --- is very important to estimate the parameters in
a neutrino factory with a very long baseline. To make it clear, we propose the
method of the Fourier series expansion of the matter profile. By using this
method, we can take account of both the matter profile effect and its
ambiguity. For very long baseline experiment, such as L=7332km, in the analysis
of the oscillation phenomena we need to introduce a new parameter ---
the Fourier coefficient of the matter profile --- as a theoretical parameter to
deal with the matter profile effects.Comment: 21 pages, 15 figure
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