Understanding the role of threading dislocations on 4H-SiC MOSFET breakdown under high temperature reverse bias stress.

The origin of dielectric breakdown was studied on 4H-SiC MOSFETs that failed after three months of high temperature reverse bias stress. A local inspection of the failed devices demonstrated the presence of a threading dislocation (TD) at the breakdown location. The nanoscale origin of the dielectric breakdown was highlighted with advanced high-spatial-resolution scanning probe microscopy (SPM) techniques. In particular, SPM revealed the conductive nature of the TD and a local increase of the minority carrier concentration close to the defect. Numerical simulations estimated a hole concentration 13 orders of magnitude larger than in the ideal 4H-SiC crystal. The hole injection in specific regions of the device explained the failure of the gate oxide under stress. In this way, the key role of the TD in the dielectric breakdown of 4H-SiC MOSFET was unambiguously demonstrated.

Transdermal Nicotine Treatment and Progression of Early Parkinson's Disease.

BACKGROUND: Epidemiologic studies show that smokers have a lower incidence of Parkinson's disease. Nicotine has been hypothesized to slow progression in early Parkinson's disease. METHODS: In a double-blind, placebo-controlled multicenter trial, we randomly assigned patients with Parkinson's disease, diagnosed within 18 months, who were in Hoehn and Yahr disease stage less than or equal to 2 (range from 0 to 5; higher scores indicate greater impairment), who were therapy naïve (except for stable monoamine-oxidase-B inhibition), and not requiring dopaminergic therapy, to transdermal nicotine or placebo. The primary end point was change in Unified Parkinson's Disease Rating Scale parts I­III (Total UPDRS) score (range from 0 to 172; higher scores indicate greater impairment) between baseline and 60 weeks (52 weeks of trial therapy, 8 weeks of washout). The first secondary end point was change in Total UPDRS from baseline to 52 weeks. Differences between groups were estimated using the Hodges­Lehmann (HL) method and tested with the exact two-sided stratified Mann­Whitney­Wilcoxon test according to the intention-to-treat principle. RESULTS: Among 163 participants, 101 were assessed for the primary end point. Mean worsening of Total UPDRS was 3.5 in the placebo versus 6.0 in the nicotine group (HL-difference with 95% CI: ­3 [­6 to 0], P=0.06). For the first secondary end point, analysis of 138 participants showed a mean worsening of 5.4 in the placebo versus 9.1 in the nicotine group (HL-difference with 95% CI: ­4 [­7 to ­1]). Dropout was mainly because of early treatment discontinuation or adverse events. Cutaneous adverse effects at the patch application site were common. In all, 34.6% of participants initiated dopaminergic therapy during participation. CONCLUSIONS: One-year transdermal nicotine treatment did not slow progression in early Parkinson's disease. (Funded by the Michael J. Fox Foundation for Parkinson's Research and others; ClinicalTrials.gov number, NCT01560754; EudraCT number, 2010-020299-42.)

Local steroid treatment in idiopathic carpal tunnel syndrome: short- and long-term efficacy.

A clinical and electrophysiological study evaluated the usefulness of local steroid therapy for carpal tunnel syndrome (CTS). To evaluate the efficacy of local steroid therapy 32 patients (53 nerves) were randomly assigned to one of two groups: one (27 nerves) received 15 mg methylprednisolone acetate injected locally and the other (26 nerves) received the same amount of saline solution. The injections were repeated after a week. Clinical and electrophysiological findings were evaluated, double blind, at regular intervals. A clear-cut efficacy of steroid treatment was found. Only 8% of nerves were not benefitted while a marked early improvement was observed in most of the nerves. In order to appraise the long-term effect of local steroid treatment on CTS, 53 patients (91 nerves) were studied and followed up by means of clinical and electrophysiological examinations performed every 2 months for 2 years. The benefit of steroid treatment was transient. About 50% of the nerves became worse within 6 months and 90% within 18 months. Only a small percentage (8%) of the nerves remained improved at the 2-years follow-up. The clinical features were not useful in foretelling the duration of the improvement, which appeared to be related to the antidromic SAP latency.

Prevalence survey of major neurological disorders in Sicily. Results of a pilot study.

A pilot study on the prevalence of neurological disorders in Sicily was carried out with a protocol never previously used in Italy. A screening questionnaire was administered to 1,601 subjects of a community, designed to identify patients with cerebrovascular diseases, epilepsy, extrapyramidal syndromes, peripheral neuropathies, migraine and intracranial neoplasms. Of 262 subjects who were identified as likely to be suffering from neurological illness, 248 (94.6%) were examined by a neurologist. Of these, 8.9% were found to be normal, 46.8% were suffering from non-neurological diseases, 44.3% had one or more neurological diseases (prevalence of 6.8%). This pilot study proved to be a good starting-point for a future major survey.

Autonomic nervous system dysfunction in chronic uraemics on haemodialysis.

A battery of cardiovascular reflex tests were performed in 35 patients with chronic renal failure on intermittent haemodialysis. An impairment of parasympathetic control was found isolated (14%) or combined with a damage of sympathetic control of cardiovascular system (26%). Moreover, maximum conduction velocity along sensory and motor fibres of posterior tibial nerve was measured in 21 patients. Autonomic dysfunction and somatic neuropathy did not appear strictly related.

Design and implementation of deformation algorithms for computer assisted orthopedic surgery: application to virtual implant database and preliminary results.

In cranio-maxillofacial and in trauma surgery while making osteosynthesis the surgeons want to reposition bone fractures and make fixation using implants and fixations devices. These devices need to be bent during surgery or prior surgery to fit geometrical boundary conditions defined by the individual anatomy of the patient. In clinical routine, surgeons must frequently repeat several times the "bend and try" process until they get the best fitting. This process often requires up to twenty minutes for a single osteosynthesis plate. A realistic deformation algorithm is then a pre-requisite to a computer-aided planning system which aims to help surgeons to optimally pre-bend the implant in respect to an individual patient bone structure. It has been shown that computer assisted planning system for bendable implant improves the results and operation outcome: shorter operation time, more accuracy, less post-operative implant failure, etc. This paper presents our preliminary results on implementing different types of deformation algorithms in the context of computer assisted orthopedic surgery.

Effect of ampicillin on neuromuscular transmission in healthy men: a single-fiber electromyographic study.

Ampicillin is considered a 'safe' drug in patients with neuromuscular transmission disorders although recently some doubt has been raised. The effect of ampicillin on neuromuscular transmission was studied in healthy subjects by means of single-fiber electromyography. A statistically significant increase of mean jitter value and of recordings with abnormally high jitter occurred after ampicillin treatment in comparison to basal examinations. Such results reaffirm that ampicillin might not be completely harmless in patients with neuromuscular transmission disturbances.

Electrophysiological study of the snout reflex in normal subjects and in parkinsonian and pseudobulbar patients.

The snout reflex appeared to be electrophysiologically present in a great majority of normal subjects. Nevertheless, a facilitation of the R2 responses of the snout reflex was found in parkinsonian patients while in pseudobulbar patients an augmentation of the R1 took place. The snout reflex, therefore, seemed to behave in a similar way as the blink reflex. In order to explain the reported findings the authors took into account the different effects of the lesions of the lateral and ventral motor system upon the oligo- and multisynaptic reflexes.

Single-fiber electromyography for studying the effect of betamethasone on normal neuromuscular junctions in man.

The effects of steroids on normal end-plate in vivo were evaluated in man by using single-fiber electromyography (SFEMG). SFEMG was performed on voluntarily activated extensor digitorium communis muscle under basal conditions and 1 week later an intramuscular injection of 4 mg betamethasone per day was administered for 7 days. Ten patients with low back pain were examined. Steroid therapy did not induce any statistically significant variation either of the mean jitter value or of the percentage of recordings with abnormally high jitter. The results of this study do not give evidence of a direct effect of steroids on normal neuromuscular junction.

Comparative analysis of autonomic and somatic dysfunction in chronic uraemia.

The relationship between autonomic dysfunction and peripheral somatic neuropathy was investigated in uraemics. The battery of autonomic tests included R-R interval variation test, deep breathing, Valsalva manoeuvre, heart rate and blood pressure responses to standing, and sustained handgrip. Maximum conduction velocity along sensory and motor fibres of the posterior tibial nerve was measured. An impairment of parasympathetic reflexes was more frequent than a sympathetic damage, but with no relationship to the degree of electrophysiological disturbances. Cardiovascular autonomic dysfunction and somatic neuropathy in uraemia result to be two different entities in incidence and perhaps in pathogenesis.

Peripheral neuropathy in amyotrophic chorea-acanthocytosis.

We investigated involvement of the peripheral nervous system in 6 patients with amyotrophic chorea-acanthocytosis. Electromyographic and neurographic findings, and pathological changes as demonstrated by examination of biopsy specimens of muscle and sural nerve indicate that most patients had an axonal sensorimotor polyneuropathy with more pronounced involvement of the distal portion of the nerves. Results obtained in one patient raised the question of an anterior horn cell disorder.

Muscle rearrangement in patients with hemiparesis after stroke: an electrophysiological and morphological study.

Skeletal muscle changes were evaluated in patients suffering from hemiparesis after stroke. Concentric needle EMG and single fiber EMG of the paretic gastrocnemius medialis muscle were performed. Maximal amplitude of H, T and M responses in calf muscles of both the affected and the unaffected sides were determined by usual electrophysiological techniques. Muscle biopsy of the lateral gastrocnemius muscle of the affected side was performed to determine the distribution of fiber types and fiber sizes. Fibrillation activity and positive sharp waves occurred in paretic muscles in patients with more recent hemiparesis while the duration of motor unit potentials was prolonged in patients with long-lasting disease. The H/M ratio was increased on the paretic side. The percentage of type 1 fibers was augmented in most patients with normal mean diameter and low atrophy factor. The percentage of type 2 fibers was reduced with decreased mean diameters and with a high atrophy factor. Such changes may be related to inactivity or transsynaptic degeneration of type 2 motoneurons as a consequence of the interruption of the corticospinal tract. Increased percentage of type 1 fibers may be due to a collateral reinnervation process or a motor unit type transformation.

Effect of ACTH4-10 on nerve fiber regeneration after sciatic nerve crush in rabbits: an electrophysiological and morphological study.

Crush of sciatic nerve in rabbits supported by morphologic and electrophysiologic data was used to evaluate the effects of ACTH4-10 on nerve fiber regeneration. Treated animals showed a statistically significant higher regeneration rate than did control rabbits. Fiber density and mean diameters of myelinated nerve fibers were measured in semithin nerve sections at 1 and 3 cm distal from the crushed point at three different time points. Nerve fiber density results were higher in ACTH4-10-than in vehicle-treated rabbits. This difference showed an unequivocal trend and attained a statistically significant level in the sections 3 cm distal from the crush. ACTH4-10 seemed therefore to have a beneficial effect on nerve fiber regeneration.