Thermodynamic Properties of the 2N-Piece Relativistic String

The thermodynamic free energy F(\beta) is calculated for a gas consisting of the transverse oscillations of a piecewise uniform bosonic string. The string consists of 2N parts of equal length, of alternating type I and type II material, and is relativistic in the sense that the velocity of sound everywhere equals the velocity of light. The present paper is a continuation of two earlier papers, one dealing with the Casimir energy of a 2N--piece string [I. Brevik and R. Sollie (1997)], and another dealing with the thermodynamic properties of a string divided into two (unequal) parts [I. Brevik, A. A. Bytsenko and H. B. Nielsen (1998)]. Making use of the Meinardus theorem we calculate the asymptotics of the level state density, and show that the critical temperatures in the individual parts are equal, for arbitrary spacetime dimension D. If D=26, we find \beta= (2/N)\sqrt{2\pi /T_{II}}, T_{II} being the tension in part II. Thermodynamic interactions of parts related to high genus g is also considered.Comment: 15 pages, LaTeX, 2 figures. Discussion in section 8 expande

EUS-derived criteria for distinguishing benign from malignant metastatic solid hepatic masses

Background Detection of hepatic metastases during EUS is an important component of tumor staging. Objective To describe our experience with EUS-guided FNA (EUS-FNA) of solid hepatic masses and derive and validate criteria to help distinguish between benign and malignant hepatic masses. Design Retrospective study, survey. Setting Single, tertiary-care referral center. Patients Medical records were reviewed for all patients undergoing EUS-FNA of solid hepatic masses over a 12-year period. Interventions EUS-FNA of solid hepatic masses. Main Outcome Measurements Masses were deemed benign or malignant according to predetermined criteria. EUS images from 200 patients were used to create derivation and validation cohorts of 100 cases each, matched by cytopathologic diagnosis. Ten expert endosonographers blindly rated 15 initial endosonographic features of each of the 100 images in the derivation cohort. These data were used to derive an EUS scoring system that was then validated by using the validation cohort by the expert endosonographer with the highest diagnostic accuracy. Results A total of 332 patients underwent EUS-FNA of a hepatic mass. Interobserver agreement regarding the initial endosonographic features among the expert endosonographers was fair to moderate, with a mean diagnostic accuracy of 73% (standard deviation 5.6). A scoring system incorporating 7 EUS features was developed to distinguish benign from malignant hepatic masses by using the derivation cohort with an area under the receiver operating curve (AUC) of 0.92; when applied to the validation cohort, performance was similar (AUC 0.86). The combined positive predictive value of both cohorts was 88%. Limitations Single center, retrospective, only one expert endosonographer deriving and validating the EUS criteria. Conclusion An EUS scoring system was developed that helps distinguish benign from malignant hepatic masses. Further study is required to determine the impact of these EUS criteria among endosonographers of all experience

Effect of resveratrol on alcohol-induced mortality and liver lesions in mice

BACKGROUND: Resveratrol is a polyphenol with important antiinflammatory and antioxidant properties. We investigated the effect of resveratrol on alcohol-induced mortality and liver lesions in mice. METHODS: Mice were randomly distributed into four groups (control, resveratrol-treated control, alcohol and resveratrol-treated alcohol). Chronic alcohol intoxication was induced by progressively administering alcohol in drinking water up to 40% v/v. The mice administered resveratrol received 10 mg/ml in drinking water. The animals had free access to standard diet. Blood levels were determined for transaminases, IL-1 and TNF-α. A histological evaluation was made of liver damage, and survival among the animals was recorded. RESULTS: Transaminase concentration was significantly higher in the alcohol group than in the rest of the groups (p < 0.05). IL-1 levels were significantly reduced in the alcohol plus resveratrol group compared with the alcohol group (p < 0.05). TNF-α was not detected in any group. Histologically, the liver lesions were more severe in the alcohol group, though no significant differences between groups were observed. Mortality in the alcohol group was 78% in the seventh week, versus 22% in the alcohol plus resveratrol group (p < 0.001). All mice in the alcohol group died before the ninth week. CONCLUSION: The results obtained suggest that resveratrol reduces mortality and liver damage in mice

Une nouvelle méthode d'étude cinétique de formation des hydrates de TBPB et de CO2 basée sur l'ATD

International audienceClathrate hydrates are crystalline compounds which can be used as phase change material (PCM) for thermal energy storage. Moreover hydrate slurries could be a good solution for industrial issues of cold distribution at various temperature levels. In fact, hydrates formed from tetra-n-butylphosphonium bromide (TBPB) + water mixtures have equilibrium conditions required for air-conditioning applications, with melting temperature at 281 K at atmospheric pressure. Moreover, their flowing conditions are also suitable. Hydrates are also able to trap molecules of carbon dioxide resulting in mixed hydrates when combined with TBPB salt. The present work investigates kinetics studies of CO2 hydrates and TBPB hydrates for various conditions of salt concentrations (15 %wt, 25 %wt and 37 %wt) and for a range of subcooling temperature between 3 and 8 K. A calorimetric method is used to determine the rate of hydrate formation thanks to a Differential Thermal Analysis (DTA). In a first time, the calorimetry method has been validated by evaluating the kinetic formation rate of CO2 hydrates then it was applied to TBPB hydrates. The results showed that the kinetic formation rate is faster when the driving force increases for each initial salt concentration. Finally, two empirical kinetics models have been tested for describing the experimental result, Avrami-Erofeev and Nakamura, and a better agreement is observed with Nakamura model

An assessment of SAPHIR calibration using quality tropical soundings

International audienceThe SAPHIR sounder (Sondeur Atmosphérique du Profil d'Humidité Intertropicale par Radiométrie) onboard the Megha-Tropiques (MT) platform is a cross track multi-channel microwave humidity sounder with 6 channels near the 183.31GHz water vapor absorption line, a maximum scan angle of 42.96° (resulting in a maximum incidence angle of 50.7°), a 1700 km wide swath and a footprint resolution of 10 km at nadir. SAPHIR L1A2 brightness temperature (BT) observations have been compared to brightness temperatures (BT) simulated by the radiative transfer model (RTM) RTTOV-10, using in situ measurements from radiosondes as input. Selected radiosonde humidity observations from the CINDY/DYNAMO campaign (September 2011 to March 2012) were spatio-temporally co-located with MT overpasses. Although several sonde systems were used during the campaign, all of the sites selected for this study used the Vaïsala RS92-SGPD system and were chosen in order to avoid discrepancies in data quality and biases. In order to interpret the results of the comparison between the sensor data and the RTM simulations, uncertainties associated with the data processing must be propagated throughout the evaluation. The magnitude of the bias was found to be dependent on the observing channel, increasing from 0.12 K for the 183.31 ± 0.2 GHz channel to 2.3 K for the 183.31 ± 11 GHz channel. Uncertainties and errors that could impact the BT biases were investigated. These can be linked to the RTM input and design, the radiosonde observations, the chosen methodology of comparison and the SAPHIR instrument itself