Improving sample preheating capabilities for dynamic loading on high-pulsed power drivers.

The CEA operates several High-Pulsed Power (HPP) drivers for dynamic loading experiments. The aim of these experiments is to provide quantitative information about the response of various materials of interest, mainly under quasi-isentropic compression. In order to improve our ability to explore these materials' behavior over a wide range of thermodynamic paths and starting from various non-ambient conditions, we developed a device capable of pre-heating both metallic and nonmetallic samples up to several hundred degrees prior to loading. This device is based on conductive heating and on a configuration that allows homogeneous heating with unprecedented temperature stability on our HPP platforms. Moreover, it is designed to allow efficient sample heating, within extremely severe electromagnetic environments associated with such platforms. The main features of this preheating device, whose design was guided by extensive thermal simulations, are presented, along with various technical solutions that enabled its insertion in a reliable experimental configuration on our HPP drivers. The results obtained from preliminary experiments on a composite material (carbon fibers embedded in epoxy resin) and on a high purity copper sample preheated to 323 K and 573 K, respectively, are presented. The performance and robustness of this heating device are potentially valuable for extending the range of studies in dynamic loading experiments for various materials under ramp compression using HPP drivers.

Recent molecular biology methods for foulbrood and nosemosis diagnosis.

Honey-bee colony losses are an increasing problem in Western countries. There are many different causes, including infections due to various pathogens. Molecular biology techniques have been developed to reliably detect and identify honey-bee pathogens. The most sensitive, specific and reliable is the quantitative real-time polymerase chain reaction (qPCR) methodology. This review of the literature describes various studies where qPCR was used to detect, identify and quantify four major honey-bee pathogens: the bacteria Paenibacillus larvae and Melissococcus plutonius (the causative agents of American foulbrood and European foulbrood, respectively) and the microsporidia Nosema apis and N. ceranae (the causative agents of nosemosis). The application of qPCR to honey-bee pathogens is very recent, and techniques are expected to improve rapidly, leading to potential new prospects for diagnosis and control. Thus, qPCR techniques could shortly become a powerful tool for investigating pathogenic infections and increasing our understanding of colony losses.

Fourier-limited seeded soft x-ray laser pulse.

We present what we believe to be the first measurement of the spectral properties of a soft x-ray laser seeded by a high-order harmonic beam. Using an interferometric method, the spectral profile of a seeded Ni-like krypton soft x-ray laser (32.8 nm) generated by optical field ionization has been experimentally determined, and the shortest possible pulse duration has been deduced. The source exhibits a Voigt spectral profile with an FWHM of 3.1+/-0.3 mA, leading to a Fourier-transform pulse duration of 4.7 ps. This value is comparable with the upper limit of the soft x-ray pulse duration determined by experimentally investigating the gain dynamics, from which we conclude that the source has reached the Fourier limit. The measured bandwidth is in good agreement with the predictions of a radiative transfer code, including gain line narrowing and saturation rebroadening.

Spread of infectious chronic bee paralysis virus by honeybee (Apis mellifera L.) feces.

Knowledge of the spreading mechanism of honeybee pathogens within the hive is crucial to our understanding of bee disease dynamics. The aim of this study was to assess the presence of infectious chronic bee paralysis virus (CBPV) in bee excreta and evaluate its possible role as an indirect route of infection. Samples of paralyzed bees were (i) produced by experimental inoculation with purified virus and (ii) collected from hives exhibiting chronic paralysis. CBPV in bee heads or feces (crude or absorbed onto paper) was detected by reverse transcription-PCR. CBPV infectivity was assessed by intrathoracic inoculation of bees with virus extracted from feces and by placement of naive bees in cages previously occupied by contaminated individuals. CBPV RNA was systematically detected in the feces of naturally and experimentally infected bees and on the paper sheets that had been used to cover the floors of units containing bees artificially infected with CBPV or the floor of one naturally infected colony. Both intrathoracic inoculation of bees with virus extracted from feces and placement of bees in contaminated cages provoked overt disease in naive bees, thereby proving that the excreted virus was infectious and that this indirect route of infection could lead to overt chronic paralysis. This is the first experimental confirmation that infectious CBPV particles excreted in the feces of infected bees can infect naive bees and provoke overt disease by mere confinement of naive bees in a soiled environment.

[Taxonomy of Apis mellifera viruses]. / Les virus infectant l'abeille Apis mellifera : le point sur leur classification.

With the exception of the filamentous virus, all viruses of the honey bee (Apis mellifera L.) are single stranded RNA viruses. At the time of their discovery, they have been classified as picorna-like viruses. Progress in molecular biology allowed sequencing some of them and revealed they were differed from picornaviruses. Two new taxons were therefore created: the Iflavirus genus and the Dicistroviridae family, which includes the genus Cripavirus, the unique genus of this family. These viruses differ from the picornaviruses at the genomic level by the order of genes and, in the case of dicistrovirus, by the organization of these genes in two ORF, each having their own regulation system. The phylogenetic analysis of members of both taxons generally shown only few similarities at the nucleotide and amino-acid level. However, within each taxon, some viruses show strong similarities, reflecting a probable common origin. Geographical isolates of the same viruses showgenetic and protein variability, which are new illustrations of the potential evolution of RNA viruses.

Detection of a novel border disease virus subgroup in Tunisian sheep.

Nine pestiviruses isolated from different batches of a contaminated Tunisian sheep pox vaccine and one Tunisian field ovine isolate of border disease virus (BDV) were studied at the antigenic and molecular levels. Seroneutralization tests were carried out on three vaccine isolates, the Tunisian field isolate and representative reference strains of the different pestivirus groups. The antigenic study showed that the Tunisian isolates were closer to the two BDV reference strains than to the Alfort-187 and the NADL reference strains. Comparison of the nucleotide sequences of the 5'-non coding regions of all the Tunisian isolates to those of other pestiviruses have shown that these isolates were distinct from the established pestivirus species. The entire N(pro)-E2 coding sequences of four Tunisian isolates were determined and compared to other pestiviruses. Segregation of these pestiviruses based on the N(pro)-E2 region was identical to that obtained with the 5'UTR sequences. The phylogenetic tree obtained with these sequences showed that the Tunisian isolates formed a separate branch between the BDV and CSFV groups, and consequently a possible new species within the pestivirus genus. However, as indicated by the antigenic study and the host origin of the isolates, the Tunisian isolates were assigned to a novel subgroup within the BDV species.

Red cell filterability and chronic renal failure.

Filterability has been studied during chronic renal failure (with creatinin level above 350 mumol/l); red cells were washed thrice with 9 g/l NaCl or 40 g/l human serum albumin), adjusted to give a PCV of 0.3 and filtered on polycarbonate sieves with pore sizes of 5 micrometer. In the uremic patients groups, the results are heterogeneous and show a significant reduction of the red cell filterability. The filtration time is not well correlated with the degree of uraemia but with the haemoglobin level.

[Congenital bundle-of-his focal tachycardias. Cooperative study of 7 cases]. / Tachycardies focales hissiennes congénitales. Etude coopérative de sept cas

The authors described seven cases of supraventricular tachycardia with atrio-ventricular dissociation, associated with the activity of an automatic focus in the bundle of His. These tachycardias, which appear at birth or are discovered at a very young age, appear to be congenital and sometimes familial, and are always isolated, having no associated cardiac abnormality. They give rise to cardiac failure, which is more marked when the rate is high (180-260/mn) and particularly resistant to treatment. The most effective form of treatment is amiodarone, almost always used in combination with digitalis. The anatomical abnormality, which was studied in the first case, is a contricting fibrosis around the main trunk of the bundle of His, and the appearances are reminiscent of those found in conditions of congenital atrio-ventricular block.

[Ventricular septal defect with aortic failure (Laubry and Pezzi syndrome). Surgical indications and results. Apropos of 20 cases]. / La comunication interventriculaire avec insuffisance aortique (syndrome de Laubry et Pezzi). Indications opératiores et résultats

The association of aortic incompetence and ventricualr septal defect is rare, but justifies the regular supervision of all patients with VSD. It seems to be found more commonly in cases where the VSD is above the crista. Early operation appears to be justified, and in a large number of cases this avoids the progressive worsening of the aortic incompetence; this in turn leads to better results with the conservative surgical procedures.