121 research outputs found
Scaled penalization of Brownian motion with drift and the Brownian ascent
We study a scaled version of a two-parameter Brownian penalization model
introduced by Roynette-Vallois-Yor in arXiv:math/0511102. The original model
penalizes Brownian motion with drift by the weight process
where and
is the running maximum of the Brownian motion. It was
shown there that the resulting penalized process exhibits three distinct phases
corresponding to different regions of the -plane. In this paper, we
investigate the effect of penalizing the Brownian motion concurrently with
scaling and identify the limit process. This extends a result of Roynette-Yor
for the case to the whole parameter plane and reveals two
additional "critical" phases occurring at the boundaries between the parameter
regions. One of these novel phases is Brownian motion conditioned to end at its
maximum, a process we call the Brownian ascent. We then relate the Brownian
ascent to some well-known Brownian path fragments and to a random scaling
transformation of Brownian motion recently studied by Rosenbaum-Yor.Comment: 32 pages; made additions to Section
DISTRIBUTIONS ISOTOPIQUES DES PRODUITS DE TRANSFERTS TRÈS INÉLASTIQUES ENTRE IONS LOURDS
On compare les distributions isotopiques expérimentales des produits de transfert très inélastiques obtenus par les réactions 40Ca (284 MeV) + 40Ca et 40Ar (295 MeV) + 232Th
HIGH EXCITATION ENERGY STRUCTURES IN HEAVY ION COLLISIONS ON A208Pb TARGET
Energy spectra of fragments from the 36Ar +208Pb reaction at 11 MeV/n and 20Ne + 208Pb reaction at 30 MeV/n were measured using a time of flight spectrometer. Structures ranging up to 130 MeV excitation energy are observed in the inelastic spectra. These structures are shown to be due to an excitation of the208Pb target nucleus
Invariance of the white noise for KdV
We prove the invariance of the mean 0 white noise for the periodic KdV.
First, we show that the Besov-type space \hat{b}^s_{p, \infty}, sp <-1,
contains the support of the white noise. Then, we prove local well-posedness in
\hat{b}^s_{p, \infty} for p= 2+, s = -{1/2}+ such that sp <-1. In establishing
the local well-posedness, we use a variant of the Bourgain spaces with a
weight. This provides an analytical proof of the invariance of the white noise
under the flow of KdV obtained in Quastel-Valko.Comment: 18 pages. To appear in Comm. Math. Phy
Fish consumption and the risk of gastric cancer: systematic review and meta-analysis
<p>Abstract</p> <p>Background</p> <p>Gastric cancer is the fourth most frequently occurring malignancy after lung, breast, and colorectal cancer, and the second most common cause of death from cancer worldwide. Epidemiologic studies have examined the possible association between fish consumption and gastric cancer, but the results were inconclusive. We conducted a systematic review and meta-analysis to examine the association between fish intake and the risk of gastric cancer.</p> <p>Methods</p> <p>PubMed was searched for studies published in English-language journals from 1991 through 2009. We identified 17 epidemiologic studies (15 case-control and 2 cohort studies) that included relative risks (RRs) or odds ratios (ORs) estimates with 95% confidence intervals (CIs) of the relationship between gastric cancer and fish consumption. Data were extracted using standardized data forms. Summary RRs or ORs for the highest versus non/lowest fish consumption levels were calculated using random-effects model. Heterogeneity among studies was examined using Q and I<sup>2 </sup>statistics.</p> <p>Results</p> <p>In this study, 5,323 cases of gastric cancer and over 130,000 non-cases were included. The combined results from all studies indicated that the association between high fish consumption and reduced gastric cancer risk was not statistically insignificant (RR = 0.87, 95% CI = 0.71-1.07).</p> <p>Conclusions</p> <p>Current evidence indicated that the association between fish consumption and risk of gastric cancer remains unclear.</p
ÉTUDE DE L'INTERACTION DE NEUTRONS DE 14 MeV SUR 238U
Le spectre d'énergie des neutrons secondaires a été observé par temps de vol de 800 keV à 14 MeV. La distribution angulaire a été étudiée de 30° à 150°. A partir des spectres expérimentaux, on a déduit les spectres de fission et d'évaporation, puis déterminé la température des noyaux excités. Une évaluation du coefficient de densité de niveaux a été faite à partir du modèle du gaz de Fermi.The fast neutron interaction of 238U has been studied by measuring the secondary neutron spectrum as a function of angle (30° ⩽ θ ⩽ 150°). The measurements were made by the time-of-flight method and spectra were observed over the energy range 800 keV-14 MeV. From experimental data, the fission and evaporation spectra have been deduced. The Fermi-gas model and the calculated temperature were used to determine the nuclear level density coefficient
A remarkable σ-finite measure on C(R+, R) related to many Brownian penalisations
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