614 research outputs found
Modeling the West Nile virus force of infection in the avian host population in Northern Italy
High Energy Neutrinos From Superheavy Dark Matter Annihilation
Superheavy ( GeV) particles produced during inflation may be the
dark matter, independent of their interaction strength. Strongly interacting
superheavy particles will be captured by the sun, and their annihilation in the
center of the sun will produce a flux of energetic neutrinos that should be
detectable by neutrino telescopes. Depending on the particle mass, event rates
in a cubic-kilometer detector range from several per hour to several per year.
The signature of the process is a predominance of tau neutrinos, with a
relatively flat energy spectrum of events ranging from 50 GeV to many TeV, and
with the mean energy of detected tau neutrinos about 3 TeV.Comment: 24 pages, 7 figure
decays in SUSY models without R-parity
Being strictly forbidden in the standard model, experimental detection of the
lepton flavor violating decays and would constitute an unmistakable indication of new physics. We
study these decays in supersymmetric models without R-parity and without lepton
number. In order to derive order of magnitude predictions for the branching
ratios, we assume a horizontal U(1) symmetry with horizontal charges chosen to
explain the magnitude of fermion masses and quark mixing angles. We find that
the branching ratios for decays with a pair in the final state are
not particularly suppressed with respect to the lepton flavor conserving
channels. In general in these models {\rm B}[b\to\mu^+\mu^-(X)]\lsim {\rm
B}[b(\bar b)\to\tau^+\mu^-(X)] \lsim {\rm B}[b\to\tau^+\tau^-(X)]. While in
some cases the rates for final states can be up to one order of
magnitude larger than the lepton flavor violating channel, due to better
efficiencies for muon detection and to the absence of standard model
contributions, decays into final states appear to be better suited to
reveal this kind of new physics.Comment: 15 pages, LaTeX, 3 ps-figures (uses epsfig.sty) Minor typos
corrected, one normalization factor added to Eq. (3.11). To be published on
Phys. Rev.
2D seismic tomography of Somma-Vesuvius: Description of the experiment and preliminary results
A multidisciplinary project for the investigation of Mt. Vesuvius structure was started in 1993. The core of the project is represented by a high resolution seismic tomography study by using controlled and natural sources. The main research objective is to investigate the feeding system of the volcano and to retrieve details of the upper crustal structure in the area. A first 2D active seismic experiment was performed in May 1994, with the aim of studing the feasibility of using tomographic techniques for exploring the volcano interiors. Particularly, this experiment was designed to obtain information on the optimal sources-receivers configuration and on the depth extension of the volume sampled by shot-generated seismic waves. 66 three-component seismic stations and 16 single-component analogue instruments were installed by several Italian and French groups to record signals generated by three on-land, underground explosions. Sources and geophones were deployed along a 30-km NW-SE profile passing through the volcano crater. Receivers were placed at an average spacing of 250 m in the middle of the recording line and at 500 m outside. The arrival time data base was complemented by first P and S readings of microearthquakes which occurred in the recent past within the volcano. The first arrival data set was preliminarily used to determine the shallow structure of the volcano by applying Thurber's (1983) tomographic inversion technique. This analysis shows evidence for a high-velocity body which extends vertically from about 400 m below the crater down to at least 3000 m and for a shallow 300-500 m thick low-velocity cover which borders the edifice. Data from the distant shot show evidence for arrivals of deep reflected/converted phases and provide information on the deeper structure under the volcano. The results from the interpretation of 2D data are used for planning a 3D tomographic survey which will be carried out in 1996
EXPRESSÃO DAS CADERINAS NOS TUMORES MAMÁRIOS EM CADELAS
Mammary tumors are among the mostcommon neoplasia of canine females. The occurrenceof metastasis may be detected by proteic markers.Among them, exist the E-cadherin, a member ofcadherin family known for its important role in theregulation of intercellular adhesion in epithelial tissues.Studies suggest that E-cadherin may function as atumor and invasion suppressor molecule. Cadherinactivity is regulated by multiple mechanisms, includinginteraction with other proteins such as catenins. In thisreview, the authors approach the cadherin family andother related adhesion proteins including its function,physiopathology and potential use as marker fordiagnosis and prognosis of canine mammary tumors.Key words: cadherin, immunohistochemistry,As neoplasias mamárias são as que maisacometem as cadelas. O desenvolvimento do câncerpode levar à ocorrência de metástases que podemser detectadas por marcadores protéicos. Um destesmarcadores é a E-caderina, um membro da famíliadas caderinas conhecida por desempenhar um papelimportante na regulação da adesão intercelular emtecidos epiteliais. Estudos apontam que as E-caderinaspodem funcionar como moléculas supressorasde tumor e de invasão. A atividade das caderinas éregulada por múltiplos mecanismos, incluindo a interaçãocom outras proteínas como as cateninas. Nestarevisão os autores abordam a família das caderinas,incluindo sua função, fisiopatologia e potencial usocomo marcadores de diagnóstico e prognóstico nasneoplasias mamárias na cadela
Optimal treatment duration of glyceryl trinitrate for chronic anal fissure: results of a prospective randomized multicenter trial
Background: Chronic anal fissure (CAF) is a painful condition that is unlikely to resolve with conventional conservative management. Previous studies have reported that topical treatment of CAF with glyceryl trinitrate (GTN) reduces pain and promotes healing, but optimal treatment duration is unknown. Methods: To assess the effect of different treatment durations on CAF, we designed a prospective randomized trial comparing 40 versus 80 days with twice daily topical 0.4% GTN treatment (Rectogesic®, Prostrakan Group). Chronicity was defined by the presence of both morphological (fibrosis, skin tag, exposed sphincter, hypertrophied anal papilla) and time criteria (symptoms present for more than 2 months or pain of less duration but similar episodes in the past). A gravity score (1 = no visible sphincter; 2 = visible sphincter; 3 = visible sphincter and fibrosis) was used at baseline. Fissure healing, the primary endpoint of the study, maximum pain at defecation measured with VAS and maximum anal resting pressure were assessed at baseline and at 14, 28, 40 and 80 days. Data was gathered at the end of the assigned treatment. Results: Of 188 patients with chronic fissure, 96 were randomized to the 40-day group and 92 to the 80-day group. Patients were well matched for sex, age, VAS and fissure score. There were 34 (19%) patients who did not complete treatment, 18 (10%) because of side effects. Of 154 patients who completed treatment, 90 (58%) had their fissures healed and 105 (68%) were pain free. There was no difference in healing or symptoms between the 40- and the 80-day group. There was no predictor of fissure healing. A low fissure gravity score correlated with increased resolution of pain (P < 0.05) and improvement of VAS score (P < 0.05) on both univariate and multivariate analysis. A lower baseline resting pressure was associated with better pain resolution on univariate analysis (P < 0.01). VAS at defecation and fissure healing significantly improved until 40 days (P < 0.001), while the difference between 40 and 80 days was not significant. Conclusion: We found no benefits in treating CAF with topical GTN for 80 days compared to 40 days. Fissure healing and VAS improvement continue until 6 weeks of treatment but are unlikely thereafter. © 2010 Springer-Verlag
Decaying Dark Matter in the Supersymmetric Standard Model with Freeze-in and Seesaw mechanims
Inspired by the decaying dark matter (DM) which can explain cosmic ray
anomalies naturally, we consider the supersymmetric Standard Model with three
right-handed neutrinos (RHNs) and R-parity, and introduce a TeV-scale DM sector
with two fields \phi_{1,2} and a discrete symmetry. The DM sector only
interacts with the RHNs via a very heavy field exchange and then we can explain
the cosmic ray anomalies. With the second right-handed neutrino N_2 dominant
seesaw mechanism at the low scale around 10^4 GeV, we show that \phi_{1,2} can
obtain the vacuum expectation values around the TeV scale, and then the
lightest state from \phi_{1,2} is the decay DM with lifetime around \sim
10^{26}s. In particular, the DM very long lifetime is related to the tiny
neutrino masses, and the dominant DM decay channels to \mu and \tau are related
to the approximate \mu-\tau symmetry. Furthermore, the correct DM relic density
can be obtained via the freeze-in mechanism, the small-scale problem for power
spectrum can be solved due to the decays of the R-parity odd meta-stable states
in the DM sector, and the baryon asymmetry can be generated via the soft
leptogensis.Comment: 24 pages,3 figure
Renormalization Group Induced Neutrino Mass in Supersymmetry without R-parity
We study supersymmetric models without R parity and with universal soft
supersymmetry breaking terms. We show that as a result of the renormalization
group flow of the parameters, a misalignment between the directions in field
space of the down-type Higgs vacuum expectation value and of the
term is always generated. This misalignment induces a mixing between the
neutrinos and the neutralinos, resulting in one massive neutrino. By means of a
simple approximate analytical expression, we study the dependence on the
different parameters that contribute to the misalignment and to . In
large part of the parameter space this effect dominates over the standard
one-loop contributions to ; we estimate 1 MeV \lsim m_\nu \lsim 1 GeV.
Laboratory, cosmological and astrophysical constraints imply m_\nu \lsim 100
eV. To be phenomenologically viable, these models must be supplemented with
some additional mechanism to ensure approximate alignment and to suppress
.Comment: 21 pages, LaTex. Few points clarified, results unchanged. Final
version to appear on Physical Review
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