Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon

Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism-observed only for times before the shock breakout at the inner cone tip-is due to self-generated resistive magnetic fields of ∼0.5-1  kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

Controlling the fast electron divergence in a solid target with multiple laser pulses

Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.

[Otosclerosis: retrospective study of 36 cases]

L'objectif de l’étude est de rapporter notre expérience concernant la prise en charge de l'otospongiose et comparer nos résultats avec ceux de la littérature. Nous rapportons une étude rétrospective concernant 36 cas d'otospongiose colligés au service d'Oto-rhino-laryngologie de l'hôpital militaire Avicenne de Marrakech, entre Janvier 2009 et Décembre 2012. L’âge moyen des patients était de 38 ans avec une nette prédominance masculine (77%). Notre étude a révélé un retard diagnostique (stades audiométriques II et III). Ce diagnostic est le plus souvent simple, très fortement suspecté dès la première consultation devant l'existence d'une surdité de transmission ou mixte à tympan normal qui constitue le signe de découverte le plus prépondérant et constant dans notre série (100%), accompagnée parfois d'acouphènes (41%). L'existence d'antécédents familiaux de la maladie a été retenue chez 33,33%. L'audiométrie tonale liminaire et la tympanométrie ont été réalisées chez tous nos patients (100%) évoquant le diagnostic dans la majorité des cas. La tomodensitométrie, non obligatoire, reste indispensable pour le diagnostic différentiel et surtout permet de prévoir les difficultés opératoires ainsi que les éventuelles associations pathologiques. Tous les patients ont subit une intervention chirurgicale comportant soit une platinectomie partielle ou totale(83%) ou une platinotomie. L’évolution et les résultats ont été généralement satisfaisants, par ailleurs nous avons constaté la survenue d'un cas de fistule périlymphatique, la persistance des acouphènes chez six patients et une surdité de transmission chez trois patients.

Deleterious effects of nonthermal electrons in shock ignition concept

Shock ignition concept is a promising approach to inertial confinement fusion that may allow obtaining high fusion energy gains with the existing laser technology. However, the spike driving laser intensities in the range of 1-10 PW/cm2 produces the energetic electrons that may have a significant effect on the target performance. The hybrid numerical simulations including a radiation hydrodynamic code coupled to a rapid Fokker-Planck module are used to asses the role of hot electrons in the shock generation and the target preheat in the time scale of 100 ps and spatial scale of 100 μm. It is shown that depending on the electron energy distribution and the target density profile the hot electrons can either increase the shock amplitude or preheat the imploding shell. In particular, the exponential electron energy spectrum corresponding to the temperature of 30 keV in the present HiPER target design preheats the deuterium-tritium shell and jeopardizes its compression. Ways of improving the target performance are suggested.

[Pseudotumor form of primary nasopharyngeal tuberculosis: apropos of 2 new cases and review of the literature]

La tuberculose primitive du nasopharynx est rare, nous présentons deux observations révélées par un aspect pseudo tumoral et à travers lesquelles nous soulevons le problème de diagnostic différentiel avec les lésions malignes du nasopharynx. La première observation concerne un jeune patient de 22 ans hospitalisé pour obstruction nasale bilatérale évoluant dans un contexte d'apyrexie et de conservation de l’état général. La nasofibrosopie et le scanner ont monté un processus tumoral évoquant une hypertrophie des végétations adénoïdes. Le deuxième cas est celui d'un homme de 45 ans tabagique chronique qui a présenté une adénopathie latérocervicale droite, une obstruction nasale et une otite séromuqueuse homolatérale. La nasophibroscopie et le scanner on montré un bourgeon tumoral postéro latéral droit du nasopharynx évoquant un carcinome nasopharyngé. Les biopsies du nasopharynx et les études histologiques, chez les deux patients, ont confirmé le diagnostic de tuberculose. La recherche d'autres localisations était négative. Le pronostic était favorable après 6 mois de traitement antibacillaire. La tuberculose primitive du cavum est rare, elle revêt le plus souvent des formes pseudotumorales et pose des problèmes de diagnostic différentiel avec les tumeurs nasopharyngées, son pronostic sous traitement antibacillaire est.

Ablation pressure driven by an energetic electron beam in a dense plasma

An intense beam of high energy electrons may create extremely high pressures in solid density materials. An analytical model of ablation pressure formation and shock wave propagation driven by an energetic electron beam is developed and confirmed with numerical simulations. In application to the shock-ignition approach in inertial confinement fusion, the energy transfer by fast electrons may be a dominant mechanism of creation of the igniting shock wave. An electron beam with an energy of 30 keV and energy flux 2-5 PW/cm(2) can create a pressure amplitude more than 300 Mbar for a duration of 200-300 ps in a precompressed solid material.

Lymphome B primitif à grandes cellules CD20-, CD79a+ apparu sur un ulcère veineux chronique de jambe

BACKGROUND

Large B-cell lymphoma of the leg in elderly subjects, of intermediate prognosis according to the new EORTC classification, may present as nodular or ulcerated forms. There has been relatively little study of the various etiological hypotheses advanced, including venous insufficiency. We report the case of an elderly man with chronic leg ulcer, recently undergoing modification, in which microscopy revealed large B-cell lymphoma (CD20-).

PATIENTS AND METHODS

A 78 year-old man presented chronic ulcer of the right leg of mixed origin with severe venous insufficiency and arteritis. In the previous 2 months, 2 nodules appeared in the centre of the ulcer. Histological examination of a skin biopsy revealed the presence of large B-cell lymphoma and immunohistochemical analysis showed positive anti-CD79a+, CD20- antibody labeling of cells. Staging studies showed only locoregional invasion. Because of the positive CD20- labeling, ZEM chemotherapy (idarubicine, cyclophosphamide, prednisolone) was given, resulting in disappearance of the nodules after four months and preliminary epidermal healing of the ulcer. Several months later, severe infectious complications necessitated amputation. Examination of the excised sample showed no residual tumor.

DISCUSSION

Many causal links have been proposed between large B-cell lymphoma of the leg and aetiologies such as infectious agents, Koebner phenomenon and chronic lymphedema, as well as various other vascular factors. A number of hypotheses were proposed in the present case. It may have been leg ulcer cutaneous B-cell lymphoma, or, more likely, development of lymphoma on a chronic mixed ulcer, with the respective roles of vascular disease, local immunosuppression and antigenic stimulation subject to debate.

Real-time PCR for quantification of human herpesvirus 6 DNA from lymph nodes and saliva

A real-time quantitative PCR assay has been developed to measure human herpesvirus 6 (HHV-6) DNA in biological specimens. The assay sensitivity was 10 copies of DNA per well, with a linear dynamic range of 10 to 10(7) copies of HHV-6 DNA. Intra- and interassay variations were, respectively, 0.88 and 0.8% for samples containing 10(2) DNA copies, 0.99 and 0.96% for samples containing 10(4) copies, and 0.76 and 0.9% for samples containing 10(6) copies. Among 34 saliva samples from healthy subjects, 26 were found to contain HHV-6 DNA (76.5%; median, 23,870 copies/ml), and following a single freeze-thaw cycle, 25 of the same samples were found to be positive for HHV-6 DNA, although at a statistically significantly lower concentration (median, 3,497 copies/ml). The assay enabled detection of HHV-6 DNA in lymph node biopsies from patients with Hodgkin's disease (HD) (13 of 37 patients [35.1%]), B-cell neoplasms (8 of 36 patients [22.2%]), and T- or NK-cell neoplasms (3 of 13 patients [23.1%]), with concentrations ranging from 100 to 864,640 HHV-6 copies per microg of DNA (HHV-6B being found in every case except two). All HD patients infected with HHV-6 presented clinically with the nodular sclerosis subtype of HD. The real-time quantitative PCR assay developed here was simple to perform and was sensitive over a wide range of HHV-6 concentrations. It therefore appears to be of potential value in clinical investigation or diagnosis of HHV-6 infection.

[Certification of cause of death in Tunisia]

We have led a study about 2251 death witch are declared during 1996 in the Great-Tunis. Results are following: The hospital deaths are as many betters certified that the physician is a specialist. The cause mention rate is about 88.6% for death observed by specialists against 28.5% for those observed by internists. Paradoxically, a precise cause mention is best for deaths that are observed outside hospitals and when the physician is an internist. Badly define morbid states represent 17.1% of outside hospitals mentioned causes against 30.8% in the Hospital. They represent 12% of causes mentioned by internist against 30.1% of those mentioned by specialists. Despite death medical certificate obligation, the strong proportion of badly defined morbid states characterizes death causes. We hope that this situation will be improved by the new model usage of the witch will be introduced since 2000. This certificate mentions death causes distinguished in initial, immediate and associated. This certificate has be the object of the decree n degree 99-1043 of 17 may 1999.

[Diabetes insipidus revealing primary malignant non-Hodgkin's lymphoma of bone]

INTRODUCTION

Diabetes insipidus is a very rare, occasionally misleading, revealing symptom of non Hodgkin's malignant lymphoma. We report a case of this uncommon association and a review of the literature is done.

EXEGESIS

Soon after a transient attack of diplopia due to a 6th cranial nerve palsy, idiopathic cerebral diabetes insipidus was diagnosed in a 32-year-old immunocompetent man. As anterior hypopituitarism was absent, the patient was discharged and treated with desmopressin acetate. Six months later, recurrence of diploplia together with raised erythrocyte sedimentation rate was observed and B cell lymphoma was observed in the iliac bone and skull, with extension into the right cavernous sinus. Both tumoral lesions led to important uptake of gallium-67. After a 26-month follow-up following intensive chemotherapy including autologous peripheral stem cell transplantation and local radiotherapy, lymphoma symptoms had disappeared, but the patient's condition had only partially improved with regard to diabetes insipidus. The association of lymphoma and diabetes insipidus which has only been reported in 14 cases is discussed.

CONCLUSION

Since endocrine symptoms are often preceding hematological diagnosis, malignant lymphomas should systematically be viewed as potential etiology of diabetes insipidus. Magnetic resonance imaging which is more sensitive than computerized tomography in revealing brain lymphomas is mandatory. Gallium scan imaging might help guide the diagnosis in some instances.

Thymoma-associated pancytopenia: effectiveness of cyclosporine A

Aplastic anemia is a rare complication of thymoma and is properly documented in only few cases. Here, we report the case of a previously healthy, 65-year-old patient who was found simultaneously to have a spindle-cell thymoma and severe hypoplastic anemia with a mild infiltration of the bone marrow by CD4+ and CD8+ T lymphocytes, CD16+ natural killer cells, and a decrease in blood CD4/CD8 ratio. Cultures of marrow erythroid progenitors demonstrated serum inhibitor. While steroids, cyclophosphamide and antilymphocyte globulin failed to improve hematopoiesis, cyclosporine A (Cy-A) led to a partial, stable remission that was sustained for 4 years. Since Cy-A has been associated with good responses in three cases of thymoma-associated red cell aplasia, we recommend its use in cases of thymoma-associated cytopenias refractory to steroids and cyclophosphamide.