Experimental discrimination of ion stopping models near the Bragg peak in highly ionized matter.

The energy deposition of ions in dense plasmas is a key process in inertial confinement fusion that determines the α-particle heating expected to trigger a burn wave in the hydrogen pellet and resulting in high thermonuclear gain. However, measurements of ion stopping in plasmas are scarce and mostly restricted to high ion velocities where theory agrees with the data. Here, we report experimental data at low projectile velocities near the Bragg peak, where the stopping force reaches its maximum. This parameter range features the largest theoretical uncertainties and conclusive data are missing until today. The precision of our measurements, combined with a reliable knowledge of the plasma parameters, allows to disprove several standard models for the stopping power for beam velocities typically encountered in inertial fusion. On the other hand, our data support theories that include a detailed treatment of strong ion-electron collisions.

Predictions for the energy loss of light ions in laser-generated plasmas at low and medium velocities.

The energy loss of light ions in dense plasmas is investigated with special focus on low to medium projectile energies, i.e., at velocities where the maximum of the stopping power occurs. In this region, exceptionally large theoretical uncertainties remain and no conclusive experimental data are available. We perform simulations of beam-plasma configurations well suited for an experimental test of ion energy loss in highly ionized, laser-generated carbon plasmas. The plasma parameters are extracted from two-dimensional hydrodynamic simulations, and a Monte Carlo calculation of the charge-state distribution of the projectile ion beam determines the dynamics of the ion charge state over the whole plasma profile. We show that the discrepancies in the energy loss predicted by different theoretical models are as high as 20-30%, making these theories well distinguishable in suitable experiments.

Controlling fast-electron-beam divergence using two laser pulses.

This Letter describes the first experimental demonstration of the guiding of a relativistic electron beam in a solid target using two colinear, relativistically intense, picosecond laser pulses. The first pulse creates a magnetic field that guides the higher-current, fast-electron beam generated by the second pulse. The effects of intensity ratio, delay, total energy, and intrinsic prepulse are examined. Thermal and Kα imaging show reduced emission size, increased peak emission, and increased total emission at delays of 4-6 ps, an intensity ratio of 10∶1 (second:first) and a total energy of 186 J. In comparison to a single, high-contrast shot, the inferred fast-electron divergence is reduced by 2.7 times, while the fast-electron current density is increased by a factor of 1.8. The enhancements are reproduced with modeling and are shown to be due to the self-generation of magnetic fields. Such a scheme could be of considerable benefit to fast-ignition inertial fusion.

[Multiple ossifying trichilemmal cysts of the scalp: a familial case]. / Kystes trichilemmaux ossifiants multiples du cuir chevelu : un cas familial.

INTRODUCTION: The trichilemmal cyst, also called pilar cyst, is a dermal epithelial cyst originating from the pilar follicle. It usually occurs in the scalp. Hereditary and ossifying cases are rare. CASE REPORT: We report the case of a 61-year-old woman presenting with familial multiple trichilemmal cysts, located in the scalp. The histological examination after surgical exeresis confirmed the diagnosis. The trichilemmal cysts featured intra-cystic ossification. The wide dimension of the lesions dimension imposed an extensive surgical scalp exeresis. Reconstruction was performed with a flap after skin expansion. DISCUSSION: The trichilemmal cyst is a benign tumor of skin appendages with a slow outcome. Multiple locations may require an extensive surgical scalp exeresis and lead to a problematic reconstruction. Hereditary cases require familial follow-up to prevent such problems.

[Sentinel node procedure in head and neck cutaneous melanoma]. / Ganglion sentinelle dans les mélanomes cutanés de l'extrémité cervicocéphalique.

INTRODUCTION: Sentinel lymph node (SLN) biopsy is frequently discussed in the management of cutaneous melanoma, especially in head and neck localizations where SLN biopsy is much more demanding. The benefits of SLN protocol are not proved yet. The aim of our study was to present our experience of SLN biopsy in head and neck cutaneous melanoma. PATIENTS AND METHODS: This retrospective study included all patients managed for head and neck malignant melanoma from 2002 to 2006. We reviewed the technique, implementation and difficulties of the procedure, postoperative outcome, and complications. RESULTS: Nineteen patients were included. An average of 2.2 lymph nodes were localized per patient using lymphoscintigraphy. Biopsy was impossible for one patient because the deep spinal node was not found. An average of 1.2 nodes was biopsied per patient. One patient presented with micrometastases. Another presented with lymphorrhea. DISCUSSION: Sentinel node biopsy is widely performed in the management of cutaneous melanoma but remains an option for these indications in the last update of the French Society of Dermatology. SLN biopsy is difficult to implement because of the complexity of head and neck lymphatic system.

X-ray polarization spectroscopy to study anisotropic velocity distribution of hot electrons produced by an ultra-high-intensity laser.

The anisotropy of the hot-electron velocity distribution in ultra-high-intensity laser produced plasma was studied with x-ray polarization spectroscopy using multilayer planar targets including x-ray emission tracer in the middle layer. This measurement serves as a diagnostic for hot-electron transport from the laser-plasma interaction region to the overdense region where drastic changes in the isotropy of the electron velocity distribution are observed. These polarization degrees are consistent with analysis of a three-dimensional polarization spectroscopy model coupled with particle-in-cell simulations. Electron velocity distribution in the underdense region is affected by the electric field of the laser and that in the overdense region becomes wider with increase in the tracer depth. A full-angular spread in the overdense region of 22.4 degrees -2.4+5.4 was obtained from the measured polarization degree.

[Necrotic angiodermatitis: evaluation of an early skin graft treatment]. / Angiodermite nécrosante : évaluation du traitement antalgique par excision-autogreffe cutanée précoce.

Necrotic angio-dermatitis is a quite frequent ischemic ulceration found in various skin microvessels diseases. It usually occurs in elderly over 60 years particularly on legs. Lesions are rapidly spreading and very painful, without any response to common pain medicines. We went, through our 21 cases series, to confirm the analgesic effect of early excision and skin grafting.

[Isolated mandibular B-cell lymphoma revealed by inferior alveolar nerve anesthesia]. / Lymphome B mandibulaire isolé révélé par une anesthésie du nerf alvéolaire inférieur.

INTRODUCTION: Mandibular lymphomas are rare and most often revealed by painless swelling. The authors report the case of a mandibular lymphoma revealed by an isolated lesion of the inferior alveolar nerve evolving for eight months. CASE REPORT: A 41-year-old male patient was followed for left mandibular pain, with progressive hypoesthesia of the left inferior alveolar nerve. The radiological assessments remained normal during eight months. Then a vestibular tumor developed in front of tooth 34. The biopsy revealed a B-cell lymphoma. No other localization was found. The patient was in complete remission two years after polychemotherapy. DISCUSSION: Our observation is unusual in its clinical presentation. Mandibular lymphomas most often present as a painless swelling, sometimes ulcerated in the mouth. They are very rarely diagnosed after an isolated hypoesthesia of V3. Lymphomas are the second most frequent head and neck lymphomas after epidermoid carcinomas, but the frequency seems to be increasing. In almost all the cases, they present as B-cell tumours of the DLBCL subtype in the WHO classification. Mandibular localizations account for only 0.6% of the cases. They are often misdiagnosed as a dental problem. The complete remission rate after chemotherapy ranges from 60 to 80% at one year. Nevertheless, the prognosis remains bad with a survival rate of only 50% at five years.

[Contribution of the posterior auricular artery in the vascularization of the facial nerve in prestylian space: anatomical study and surgical applications]. / Contribution de l'artère auriculaire postérieure à la vascularisation du nerf facial dans l'espace préstylien : étude anatomique et conséquences chirurgicales.

INTRODUCTION: The aim of our study was to establish a systematization of collateral branches originating from posterior auricular artery to facial nerve in prestylian space. MATERIALS AND METHODS: Thirty posterior auricular arteries were studied on 15 fresh cadavers after selective patent blue injection. We observed subsequent colouration of facial nerve. Number and topography of collateral branches were highlighted. RESULTS: Posterior auricular artery supplied facial nerve in 67%. Collateral branches dedicated to facial nerve could be classified into three types: type 1 corresponded to one artery in prestylian space, type 2 to several branches in prestylian space; finally type 3 featured several branches originating from posterior auricular artery in prestylian space on the one hand, in superficial retroauricular area on the other hand. CONCLUSION: Posterior auricular artery is the main blood supply to facial nerve in prestylian space. In most of the cases, branches to facial nerve originate deeply in parotid space. Nevertheless nervous branches may originate from superficial retroauricular segment of posterior auricular artery. Their damage during surgical procedures as bat ear surgery can cause definitive facial nerve palsy.

[Trapezio second metacarpal joint: anatomical study and clinical matters]. / Articulation du trapèze avec le second métacarpien: étude anatomique et intérêts cliniques.

INTRODUCTION: An unusual dislocation of the column of the thumb associated with a fracture of the base of the second metacarpal inspired an anatomical study of the trapeziosecond metacarpal joint. MATERIALS AND METHODS: Forty-five dissections of the palmar aspect of trapeziometacarpal joint aimed at focusing on palmar ligaments and tendons reinforcing the joints. RESULTS: Trapeziosecond metacarpal joint is a constant little diarthrosis reinforced by a palmar ligament stressed between the crest of the trapezium and the base of the second metacarpal. The tendon of flexor radialis carpi muscle is an active link due to strong vinculae to trapezium bone and distal attachment to the bases of both second and third metacarpals. CONCLUSION: The connections between the trapezium and the base of the second metacarpal bone play a role in the treatment of thumb instability and their mechanical importance is illustrated in our original clinical observation.

[Orthopaedic treatment of extraarticular condylar fractures of the mandible: retrospective study of 39 unilateral cases]. / Traitement orthopédique des fractures extra-articulaires de la région condylienne de la mandibule : étude rétrospective de 39 fractures unifocales.

INTRODUCTION: Although for an increasing number of authors open reduction and internal fixation (ORIF) is becoming the standard of care for mandibular subcondylar fractures, functional treatment is still performed worldwide. The aim of this study was to evaluate the results of functional treatment in isolated mandibular subcondylar fractures. MATERIAL AND METHODS: Patients presenting with an isolated low subcondylar fracture between 1998 and 2004 were enrolled in a retrospective study. We focused on the epidemiology, type of fracture, degree of displacement, treatment protocol and short-term outcome. Patients were interviewed to evaluate long-term results. RESULTS: Thirty-nine patients were enrolled in this retrospective study. The mean displacement was 15 degrees of medial angulation and a shortening of the ramus ranging around 5mm. Thirty-one patients recovered normal mandibular function (mouth opening more than 45 mm, with no or minimal deviation). Sixteen presented with TMJ disorders, deemed minor by the patients themselves. None of them required any specific treatment. Eighteen had posttraumatic occlusal discomfort corrected by dentistry or prosthetic adaptation. Long-term follow-up X-rays showed minor residual condylar displacement. In all cases, patients estimated their treatment acceptable. DISCUSSION: The orthopedic treatment of low subcondylar fractures provides acceptable functional results. This technique is simple, safe and remains a valuable therapeutic option. In the future, experience with surgical management will probably lead to specific indications of both closed and open methods.

High flux of relativistic electrons produced in femtosecond laser-thin foil target interactions: characterization with nuclear techniques.

We present a protocol to characterize the high energy electron beam emitted in the interaction of an ultraintense laser with matter at intensities higher than 10(19) W cm(-2). The electron energies and angular distributions are determined as well as the total number of electrons produced above a 10 MeV threshold. This protocol is based on measurements with an electron spectrometer and nuclear activation techniques, combined with Monte Carlo simulations based on the GEANT3 code. The method is detailed and exemplified with data obtained with polypropylene and copper thin solid targets at a laser intensity of 2x10(19) W cm(-2). Special care is taken of the different sources of uncertainties. In particular, the reproducibility of the laser shots is considered.

Fast electron transport and induced heating in solid targets from rear-side interferometry imaging.

Fast adiabatic plasma heating of a thin solid target irradiated by a high intensity laser has been observed by an optical fast interferometry diagnostic. It is driven by the hot electron current induced by the laser plasma interaction at the front side of the target. Radial and longitudinal temperature profiles are calculated to reproduce the observed rear-side plasma expansion. The main parameters of the suprathermal electrons (number, temperature, and divergence) have been deduced from these observations.

[Third molar surgery under general anesthesia: a review of 180 patients]. / Extraction des dents de sagesse sous anesthésie générale : à propos de 180 patients.

BACKGROUND: Third molar surgery is an important part of the activity in a maxillofacial surgery department. This common activity is often under-evaluated by patients who forget its surgical aspect. The aim of this study was to evaluate our practice, and especially complications, with special consideration given to medicolegal aspects. MATERIALS AND METHODS: All the patients operated between September 2004 and July 2006 were enrolled in a retrospective study. This population is described, with the indications, follow-up, and complications. RESULTS: One hundred and eighty patients were reviewed (sex-ratio 1, mean age 27 years). The most frequent indications were impaction and pain. The mean duration of hospitalization was 1.7 days and temporary disability, one week. Local infection occurred in 8%; there was neurological complication in 2% for the inferior alveolar nerve, and 1% for the lingual nerve. These were all transient cases. DISCUSSION: Third molar surgery is an important and profitable part of the activity in a maxillofacial surgery department. Standardized information is necessary even if the rate of complications remains low.

Direct evidence of strongly inhomogeneous energy deposition in target heating with laser-produced ion beams.

We report on strong nonuniformities in target heating with intense, laser-produced proton beams. The observed inhomogeneity in energy deposition can strongly perturb equation of state (EOS) measurements with laser-accelerated ions which are planned in several laboratories. Interferometric measurements of the target expansion show different expansion velocities on the front and rear surfaces, indicating a strong difference in local temperature. The nonuniformity indicates at an additional heating mechanism, which seems to originate from electrons in the keV range.

Untreated growth hormone deficiency with extremely short stature, bone dysplasia, cleft lip--palate and severe mental retardation in a 26-year-old man with a de novo unbalanced translocation t(1;12)(q24;q24).

We report on a 26-year-old patient presenting with extremely short stature (height 72cm, weight 6.5kg, OFC 42.5cm), facial dysmorphism, cleft lip--palate, severe mental retardation and de novo 1q24.2--q25.2 and 12q24.31 interstitial deletion. He was the only child of non-consanguineous parents and his birth length was 43cm. He had severe feeding difficulties and required enteral nutrition until the age of 3 years. Standard cytogenetic analysis showed an apparently balanced de novo translocation t(1;12)(q24;q24). Endocrine studies at 11 years of age for severe growth retardation revealed multiple pituitary hormone deficiency with severe growth hormone deficiency, but the child was untreated because of associated mental retardation. At 26 years of age, he could not walk or speak and had no signs of puberty. Investigations revealed spondylo-epi-metaphyseal dysplasia with severe osteoporosis, enlarged aorta when compared to the patient's size and apparently normal pituitary development. High resolution karyotype showed a 1q24-q25 deletion, and comparative genomic hybridization studies confirmed the 1q interstitial deletion. FISH studies of both breakpoints using PACs and BACs enabled us to further characterize the 1q interstitial deletion (1q24.2-1q25.2) and also revealed a 12q24.31 interstitial microdeletion. This case is compared with previously reported patients with similar deletions, but the untreated pituitary deficiency could also be responsible in part for the severity of the growth deficiency. This observation is of interest for two reasons. First, these deletions could be a clue in the search for a gene responsible for growth hormone deficiency/midline defects. Second, it shows the importance of molecular cytogenetics in the study of de novo apparently balanced translocation with abnormal phenotype.

[Socioeconomic adjustment in young cleft lip-palate patients]. / Intégration socioéconomique des jeunes adultes opérés de fentes labiomaxillopalatines.

INTRODUCTION: The aim of our study was to evaluate socioeconomic adjustment of young adults after treatment for cleft lip and palate. MATERIALS AND METHODS: A retrospective study was made including patients born from 1975 to 1986 and followed-up in our department. The investigation was based on response to a questionnaire that partly replicated a national survey of social and economic life in the population (standard of living survey Burgundy, Insee France 1999). The control group was constituted by individuals taken from a regional probability sample of households. This report covered education, employment, and marriage. RESULTS: 41 patients were enrolled in this retrospective study and compared to 972 young adults. There was a significant delay in the independence process, regarding housing and marriage. Patients remained in normal limits concerning employment. However the patients' education history showed a significant delay, and a higher rate of vocational courses. DISCUSSION: The independence process showed a significant delay in cleft lip-palate patients, as well as education history. Nevertheless the final socioeconomic adjustment was similar to that of the general population.

[Peri-implantitis or squamous cell carcinoma?]. / Péri-implantite ou carcinome épidermoïde?

INTRODUCTION: Squamous cell carcinoma developed around dental implants has seldom been described. It simulates peri-implantitis. The authors present two cases and a literature review. CASE REPORTS: A 70 year-old woman presented with an exophytic tumor developed around dental implants placed in the anterior part of the mandible. Panoramic X-rays showed major osteolysis, especially around the distal abutment implants. A 72 year-old patient, smoker, presented with chronic lichen planus; he was carrying two implants supporting an overdenture with ball-attachments, placed 15 years before. He presented with an ulcerated symphyseal tumor, bone loss around implant in position 43. The implant had been spontaneously pushed out. In both cases the diagnosis was squamous cell carcinoma. DISCUSSION: Few cases of squamous cell carcinoma developed around dental implants have been reported. They initially mimic peri-implantitis. The carcinogenic role of the implant has never been established. Another hypothesis is the migration of malignant cells, originating from a mucosal tumor, through the sulcus. Risk factors for squamous cell carcinoma (smoking or alcohol consumption, precancerous lesions) are an indication for a permanent follow-up. Biopsies will prove the diagnosis.