Comparison of max-plus automata and joint spectral radius of tropical matrices

Weighted automata over the max-plus semiring S are closely related to finitely generated semigroups of matrices over S. In this paper, we use results in automata theory to study two quantities associated with sets of matrices: the joint spectral radius and the ultimate rank. We prove that these two quantities are not computable over the tropical semiring, i.e. there is no algorithm that takes as input a finite set of matrices M and provides as output the joint spectral radius (resp. the ultimate rank) of M. On the other hand, we prove that the joint spectral radius is nevertheless approximable and we exhibit restricted cases in which the joint spectral radius and the ultimate rank are computable. To reach this aim, we study the problem of comparing functions computed by weighted automata over the tropical semiring. This problem is known to be undecidable and we prove that it remains undecidable in some specific subclasses of automata

Theoretical profiles of the Mg + resonance lines perturbed by collisions with He

International audienceThe effects of collision broadening by He are central to understanding the opacity of cool stellar atmospheres. Aims. DZ white dwarfs show metal lines which are, in many cases, believed to come from some rocky material, a remnant of a former exoplanetary system. The analysis of the Mg + resonance lines is a valuable method to determine the chemical abundances in these systems. Methods. Unified profiles of the strongest of the UV lines of Mg + have been calculated in the semi-classical approach using very recent ab initio potential energies. Results. We present the first theoretical line profile calculations of the resonance lines of Mg + that have been perturbed by helium in physical conditions of atmospheres in helium-rich white dwarfs with metal traces

Post cardiac surgery vasoplegia is associated with high preoperative copeptin plasma concentration

International audienceABSTRACT: INTRODUCTION: Post cardiac surgery vasodilatation is possibly related to a vasopressin deficiency that could be related to a chronic stimulation of the adeno-hypophysis. To assess vasopressin system activation, perioperative course of copeptin and vasopressin plasma concentrations have been studied in consecutive patients operated on cardiac surgery. METHODS: 64 consecutive patients scheduled for elective cardiac surgery with cardiopulmonary bypass were studied. Haemodynamic, laboratory and clinical data were recorded before and during cardiopulmonary bypass, and at the 8th post-operative hour (H8). At the same time, point's blood was withdrawn to determine plasma concentrations of arginine-vasopressin (AVP, radioimmunoassay) and copeptin (immunoluminometric assay). Post cardiac surgery vasodilation (PCSV) was defined as a mean arterial blood pressure less than 60 mmHg with a cardiac index [equal to or greater than] 2.2 L * min^-1 * m^-2, and was treated with norepinephrine (NE) in order to restore a mean blood pressure > 60 mmHg. Patients with PCSV were compared to the other patients (controls). Student's t, Fisher's exact test, or non parametric tests (Mann Whitney, Wilkoxon) were used when appropriate. A correlation between AVP and copeptin has been evaluated and a receiver-operator characteristic (ROC) analysis was calculated to assess the utility of preoperative copeptin to distinguish between controls and PCSV patients. RESULTS: Patients who experienced a PCSV have significantly higher copeptin plasma concentration before cardiopulmonary bypass (P <0.001) but lower AVP concentrations at H8 (P <0.01) than controls. PCSV patients had preoperative hyponatremia and decreased left ventricle ejection fraction, and experienced more complex surgery (redo). The area under the ROC curve of preoperative copeptin concentration was 0.86[plus/minus]0.04 [95%CI: 0.78-0.94] (P <0.001). The best predictive value for preoperative copeptin plasma concentration was 9.43 pmol/L with a sensitivity of 90% and a specificity of 77%. CONCLUSIONS: High preoperative copeptin plasma concentration is predictive of PSCV and suggests an activation of the AVP system before surgery that may facilitate depletion of endogenous AVP stores and a relative AVP deficit after surgery

Calcinose interstitielle diffuse chez le chien

Karsenti G., Groulade Paul, Guillon J.-C. Calcinose interstitielle diffuse chez le chien. In: Bulletin de l'Académie Vétérinaire de France tome 120 n°6, 1967. pp. 269-274

Particules d’aspect viral dans les cellules du lymphosarcome du chien

Dans le tissu ganglionnaire de deux chiens atteints de lymphosarcome, il a été trouvé des particules rappelant les virus des leucémies murines

Performances of Solid Oxide Cells with La0.97_{0.97}Ni0.5_{0.5}Co0.5_{0.5}O3−δ_{3-\delta} as Air-Electrodes

Based on previous studies of perovskites in the quasi-ternary system LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}$, La$_{0.97}$Ni$_{0.5}$Co$_{0.5}$O$_{3}$ (LNC) is chosen as the most promising air-electrode material in the series for solid oxide cells (SOCs). The properties of the material itself have been investigated in detail. However, the evaluation of LNC97 air electrodes in practical SOCs is still at a very early stage. In the present study, SOCs were prepared based on LNC97 air electrodes. The I-U performance of the SOCs in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes, i.e. reversible SOCs (r-SOCs), was investigated systematically for different air-electrode designs, temperatures and fuel gases. In general, the performance of the r-SOCs tested in the present study is higher than the published results of other LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}$-based SOCs and is comparable to or even better than state-of-the-art La$_{1-x}$Sr$_{x}$Fe$_{1-y}$Co$_{y}$O$_{3}$ (LSCF)-based SOCs. Mid-term operation of about 1000 h for SOCs in both SOFC and SOEC modes primarily proved the stability of LNC97-based air electrodes. Impedance spectra were systematically applied to understand the polarization processes of the SOCs

G0^0 Electronics and Data Acquisition (Forward-Angle Measurements)

The G$^0$ parity-violation experiment at Jefferson Lab (Newport News, VA) is designed to determine the contribution of strange/anti-strange quark pairs to the intrinsic properties of the proton. In the forward-angle part of the experiment, the asymmetry in the cross section was measured for $\vec{e}p$ elastic scattering by counting the recoil protons corresponding to the two beam-helicity states. Due to the high accuracy required on the asymmetry, the G$^0$ experiment was based on a custom experimental setup with its own associated electronics and data acquisition (DAQ) system. Highly specialized time-encoding electronics provided time-of-flight spectra for each detector for each helicity state. More conventional electronics was used for monitoring (mainly FastBus). The time-encoding electronics and the DAQ system have been designed to handle events at a mean rate of 2 MHz per detector with low deadtime and to minimize helicity-correlated systematic errors. In this paper, we outline the general architecture and the main features of the electronics and the DAQ system dedicated to G$^0$ forward-angle measurements.Comment: 35 pages. 17 figures. This article is to be submitted to NIM section A. It has been written with Latex using \documentclass{elsart}. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment In Press (2007