Plastic scintillator-based dosimeters for ultra-high dose rate (UHDR) electron radiotherapy.

This paper reports the development of dosimeters based on plastic scintillating fibers imaged by a charge-coupled device camera, and their performance evaluation through irradiations with the electron Flash research accelerator located at the Centro Pisano Flash Radiotherapy. The dosimeter prototypes were composed of a piece of plastic scintillating fiber optically coupled to a clear optical fiber which transported the scintillation signal to the readout systems (an imaging system and a photodiode). The following properties were tested: linearity, capability to reconstruct the percentage depth dose curve in solid water and to sample in time the single beam pulse. The stem effect contribution was evaluated with three methods, and a proof-of-concept one-dimensional array was developed and tested for online beam profiling. Results show linearity up to 10 Gy per pulse, and good capability to reconstruct both the timing and spatial profiles of the beam, thus suggesting that plastic scintillating fibers may be good candidates for low-energy electron Flash dosimetry.

Pressure anisotropy and small spatial scales induced by velocity shear.

By including the full pressure tensor dynamics in a fluid plasma model, we show that a sheared velocity field can provide an effective mechanism that makes the initial isotropic pressure nongyrotropic. This is distinct from the usual gyrotropic anisotropy related to the fluid compressibility and usually accounted for in double-adiabatic models. We determine the time evolution of the pressure agyrotropy and discuss how the propagation of "magnetoelastic perturbations" can affect the pressure tensor anisotropization and its spatial filamentation, which are due to the action of both the magnetic field and the flow strain tensor. We support this analysis with a numerical integration of the nonlinear equations describing the pressure tensor evolution.

Hamiltonian stochastic processes induced by successive wave-particle interactions in stimulated Raman scattering.

The long-time dynamics of particles interacting resonantly with large-amplitude coherent plasma wave is investigated in the kinetic regime of stimulated Raman scattering in which particle trapping plays a major role (and which corresponds to a high value of the parameter k_{EPW}lambda_{D}, where k_{EPW} is the plasma wave vector and lambda_{D} is the electron Debye length). Using Vlasov simulations, the dynamics of such particles become stochastic when repeated wave-particle interactions take place. For small values of the ratio tau_{auto}/tau_{b} of the autocorrelation time to the bounce time of particle (condition usually met in backward propagation of the scattered wave) the turbulent regime results in the merging of phase-space trapping vortices according to a weak turbulencelike scenario. For high values of tau_{auto}/tau_{b} (or narrow spectrum of longitudinal electric field as met when only one plasma wave is present), the stochasticity is now induced by particle trapping, detrapping, and retrapping in the adiabatically fluctuating field. The stochastic transitions performed by resonant particles above (or below) the separatrix limit in phase space determine now the long-time plasma evolution.

[One-year follow-up and mobility assessment of schizophrenic patients in the Liege psychiatric care network]. / Evaluation d'un an de parcours de patients schizophrènes en service psychiatrique liégeois.

OBJECTIVE: The study was aimed at assessing the clinical evolution and mobility of schizophrenic patients within the healthcare network of the Psychiatric Platform of Liege (Belgium) after a one-year follow-up period. MATERIAL AND METHODS: The study material consisted of a random sample of 184 patients with schizophrenia drawn from the population of schizophrenic patients treated in the Liege psychiatric care network. The characteristics of these patients have been described previously (18). The 184 patients were followed-up for one-year and reassessed at the end of this period. Mobility (ie, changes between psychiatric care institutions, including home) was recorded for each patient within the institutional network. The diagnosis of schizophrenia was based on the DSM IV. Demographic, social and global functioning (GAF scale) data were collected from the "Résumé psychiatrique Minimum (RPM)", a clinical summary which has been imposed by the Belgian Ministry of Public Health for each psychiatric hospital stay. Symptom components were derived from the Psychosis Evaluation tool for Common Use by Caregivers (PECC). RESULTS: Among the 184 patients enrolled in the initial analysis, 6 refused to participate in the follow-up study. The 178 remaining schizophrenic patients included 131 men (74%) and 47 women (26%) with a mean age of 43.1 +/- 13.6 and 48.8 +/- 14.9 years, respectively (p<0.05). The majority of patients (53%) suffered from paranoid schizophrenia. At baseline, 63% of the patients were hospitalised full-time, 6% part-time and 31% received ambulatory care. During the one-year follow-up period, 4 patients died, including one from suicide. When considering mobility, 48% of the patients experienced at least one change of institution, whereas 52% of the patients didn't change at all (see figure 1). The total number of changes over the 1-year period amounted 189, yielding a mean value of 1.1 changes per patient per year. Changes mostly occurred between institutions of similar care setting (see figure 2). Transfers (30%) were also observed directly between hospital and home. A multivariate Poisson regression analysis showed that the number of changes was unrelated to gender and initial care setting but decreased with age (p<0.0001). It was also higher for patients with schizo-affective disorders (2.5 +/- 1.9, p<0.01) or with residual type (1.2 +/- 1.8; p<0.05) than for patients with other types of schizophrenia (ranging from 0.3 +/- 0.5 to 0.9 +/- 1.4). No association was found with initial GAF or PECC, except for negative symptoms (p<0.05). After one year, despite the high proportion of institutional changes (48% of the patients), the distribution of the patients according to care setting remained the same (p=0.77). However, GAF scores significantly improved from 39.7 +/- 16.1 to 44.4 +/- 16.1 (p<0.0001) and likewise for total PECC scores (70 +/- 19.1 vs 63.2 +/- 19.4, p<0.001). Excitatory and disease perception items of the PECC remained unchanged. CONCLUSION: The present study reveals that mobility within the institutional network did affect about half of the schizophrenic patients. Mobility was related to age, type of schizophrenia and disease evolution. Changes occur mainly between psychiatric structures of similar care setting but also directly from hospital to home without passing through an intermediate care structure. Further efforts should be made to provide schizophrenic patients with a more coordinated care provision throughout the course of their disease.

Three-dimensional magnetic structures generated by the development of the filamentation (Weibel) instability in the relativistic regime.

We present three-dimensional, fully relativistic, fluid simulations of the dynamics of inhomogeneous counter streaming beams with the aim of understanding the magnetic structures that can be expected to form as a consequence of the development of the so-called Weibel instability. Ringlike structures in the transverse direction are generated as a consequence of the development of a spatially resonant mode. We describe the structures generated by beams of equal initial density and velocity and by a fast, less dense beam compensated by a slower, denser beam. We consider these two cases as schematic models of a laser produced beam propagating in a plasma with nearly equal density and in a plasma much denser than the injected beam.

[An example of the evaluation of risks of repeated movements in pottery plants located in western Liguria]. / Un esempio di valutazione del rischio da movimenti ripetuti in aziende del comparto ceramico del ponente ligure.

Pottery manufacturing is typical in western Liguria and it represents one of the most important economical resources of this area. The major part of manufacturers are handicrafts, although some bigger firms have developed industrialized production cycles. Both types of productions, however, require hand work at almost all levels of processing. Most workers are women and a significant part of these are affected by Carpal Tunnel Syndrome. INAIL (Direzione Regionale Liguria) carries on a dedicated program for employers' insurance and Health & Safety implementation but--in order to do so--INAIL needs to achieve more knowledge about risk factors in this field. The aim of this study was to assess CTD risk in two pottery industries located in Albisola: in particular, two productions Cycles equipped with assembly lines have been investigated. The method used for risk assessment was OCRA Index (OCcupational Repetitive Actions), adapted to be applied to pottery industries.

Secondary instabilities and vortex formation in collisionless-fluid magnetic reconnection.

It is shown that the pattern of current layers formed within a magnetic island in the nonlinear phase of magnetic field line reconnection in a collisionless two-dimensional fluid plasma is subject to the onset of a secondary instability, the effect of which increases with decreasing electron temperature. In the cold electron limit the saturation of the island growth is accompanied by a turbulent redistribution of the current layers and by the development of long lived fluid vortices while, in the opposite limit, the current layer structure remains regular.

[Diagnostic, symptomatic and sanitary assessment of schizophrenic patients in Liege psychiatric institutions]. / Analyse diagnostique, symptomatologique et sanitaire des patients schizophrènes en service psychiatrique liégeois.

This study was designed to provide a diagnostic, symptomatologic and sanitary assessment of schizophrenic patients in the network of institutions of the Plate-Forme Psychiatrique Liégeoise (Liège, Belgium). The diagnosis of schizophrenia was based on the DSM IV. Demographic, social and global functioning (GAF scale) data were collected from the Résumé Psychiatrique Minimum (RPM) , a clinical summary which has been imposed for each psychiatric hospital stay by the Belgian Ministry of Public Health. Symptoms components were derived from the Psychosis Evaluation tool for Commom Use by Caregivers (PECC). In the 44 participating institutions, 793 cases of schizophrenia were reported (533 men and 260 women) with a mean age of 46.1 14.4 years. The study confirmed the predominance of men in schizophrenia (67%) but revealed that women were about 6 years higher than men. PECC symptoms were studied in a random sample of 184 patients extracted from the 793 initial patients and analysed with respect to age, sex and type of care (full-time or part-time hospitalization, ambulatory care). Negative, cognitive and total PECC scores did not vary with sex but were positively correlated with age. Hospitalized patients were significantly older than the others. The cognitive deficit was significantly higher in hospitalized patients than in other patients, while the perception of the disease tended to be more apparent in ambulatory than in hospitalized patients. Data were also related to social information and global functioning. The GAF scores increased with age but were comparable in men and women. Moreover, GAF scores were significantly lower in catatonic type schizophrenia patients than in others.