Demonstration of a semiconductor external cavity laser using a UVwritten grating in a planar silica waveguide

The authors report the first demonstration of a semiconductor external cavity waveguide laser, modulated at 2.5 Gbit/s over 100 km of standard optical fibre using a UV written grating in a planar silica waveguide as the feedback element     

Selection of rainbow trout resistant to viral haemorrhagic septicaemia virus and transmission of resistance by gynogenesis

In 1984 a programme of selection for resistance to viral haemorrhagic septicaemia virus (VHSV) in rainbow trout was initiated. The progenies of 14 males were submitted to a VHSV waterborne challenge. The mortality ranged from 30 to 95% and the heritability of resistance was estimated to be 0.63 +/- 0.26. One male consistently provided the most resistant offspring, and the second generation was produced from sires and dams selected among these families. The mean resistance improved and several females giving birth to resistant offspring were identified (0-10% mortality while the mortality in the controls was from 70 to 90%). The meiotic gynogenetic progeny of these females also demonstrated high resistance (mortality less than 10%). The role of superficial tissues in the resistance was confirmed and there was a striking difference in the growth of VHSV in fins excised and infected in vitro. The fins from resistant fish replicated the virus poorly as compared with the fins of susceptible fish.     

High dose intravenous immune globulins and plasma exchange in Guillain-Barré Syndrome

We report the effects of treatment with plasma-exchange (PE) and intravenous immune globulins (IVIg) in 36 out of 50 patients with Guillain-Barré syndrome (GBS) recruited by an incidence study in the Emilia-Romagna region of Italy. Comparison of the patients treated with PE and IVIg showed no significant differences in terms of effectiveness in improving the clinical course of GBS: at one month, respectively 11.1% and 25% had recovered, and 55.5% and 58.3% had improved by at least one grade. These results are in agreement with those of the Dutch GBS trial. No relapses were observed in either group. Moreover, our results showed no difference in clinical outcome at 1 and 3 months between the patients receiving only one therapy and those receiving two; a second cycle of therapy did not seem to improve the clinical course of the disease significantly. We conclude that PE and IVIg are both safe and effective therapies for GBS.     

Comparative study of the treatment of prostatic adenoma: laser photocoagulation versus endoscopic resection

OBJECTIVE: Resection of the prostate using a Nd YAG laser is designed to destroy benign prostatic hyperplasia responsible for bladder neck obstruction. This technique is currently under investigation. PATIENTS AND TECHNIQUE: A total of 56 patients, with a minimal follow-up of 6 months and presenting indications for endoscopic resection of the prostate were treated by TULIP [22] or VLAP [34] laser coagulation. The objective and subjective results were compared to a group of patients [30] treated by endoscopic resection during the same period. Results are expressed as the percentage of patient responding to treatment in terms of objective (peak flow rate > 15 ml/s with improvement > 30% or between 12 and 15 ml, but improvement > 50%) and subjective parameters (IPSS < 7 and improvement > 30% or between 7 and 10, but improvement < 50%). RESULTS: With a minimal follow-up of 6 months, the objective response rates were 55.5% (TULIP), 84.6% (VLAP) and 83.2% (TURP), while the subjective response rates were 55.5% (TULIP), 92.3% (VLAP) and 83.3% (TURP). The hospital stay was significantly shorter in the laser group (2.1 VLAP and 3.3 TULIP; 4.93 TURP). In the TULIP group, 3 patients were incontinent and 4 developed chronic prostatitis. At 6 months, 4 patients in the VLAP group and 6 patients in the TULIP group had to undergo a complementary TURP. CONCLUSION: These results indicate that laser photocoagulation is effective in the treatment of benign prostatic hyperplasia. The VLAP technique appears to be better adapted to this indication. The benefit of VLAP will be more clearly demonstrated by the randomized study currently underway, provided the length of hospital stay, postoperative complications and cost-effectiveness ratio are taken into account. In contrast, the TULIP system is associated with numerous complications which appear to be unacceptable.     

Machine learning in control of functional electrical stimulationsystems for locomotion

Two machine learning techniques were evaluated for automatic design of a rule-based control of functional electrical stimulation (FES) for locomotion of spinal cord injured humans. The task was to learn the invariant characteristics of the relationship between sensory information and the FES-control signal by using off-line supervised training. Sensory signals were recorded using pressure sensors installed in the insoles of a subject's shoes and goniometers attached across the joints of the affected leg. The FES-control consisted of pulses corresponding to time intervals when the subject pressed on the manual push-button to deliver the stimulation during FES-assisted ambulation. The machine learning techniques used were the adaptive logic network (ALN) and the inductive learning algorithm (IL). Results to date suggest that, given the same training data, the IL learned faster than the ALN while both performed the test rapidly. The generalization was estimated by measuring the test errors and it was better with an ALN, especially if past points were used to reflect the time dimension. Both techniques were able to predict future stimulation events. An advantage of the ALN over the IL was that ALN's can be retrained with new data without losing previously collected knowledge. The advantages of the IL over the ALN were that the IL produces small, explicit, comprehensible trees and that the relative importance of each sensory contribution can be quantified     

An analytical model for alloyed ohmic contacts using a trilayer transmission line model

This paper describes a Transmission Line Model approach to the modeling and analysis of alloyed planar ohmic contacts. It briefly reviews the standard Transmission Line Model (TLM) commonly used to characterize a planar ohmic contact. It is shown that in the case of a typical Au-Ge-Ni alloyed ohmic contact, a more realistic model based on the TLM should take into account the presence of the alloyed layer at the metal-semiconductor interface. In this paper, such a model is described. It is based on three layers and the two interfaces between them, thus forming a Tri-Layer Transmission Line Model (TLTLM). Analytical expressions are derived for the contact resistance Re and the contact end resistance Rc of this structure, together with a current division factor, S. Values for the contact parameters of this TLTLM model are inferred from experimentally reported values of Re and Re for two types of contact. Using the analytical outcomes of the TLTLM, it is shown that the experimental results obtained using a standard TLM can have considerable discrepancies.<>     

Si/SiGe epitaxial-base transistors. I. Materials, physics, andcircuits

A detailed review of SiGe epitaxial base technology is presented, which chronicles the progression of research from materials deposition through device and integration demonstrations, culminating in the first SiGe integrated circuit application. In part I of this paper, the requirements and processes for high-quality SiGe film preparation are discussed, with emphasis on fundamental principles. A detailed overview of SiGe HBT device design and implications for circuit applications is then presented