Note: three-dimensional stereolithography for millimeter wave and terahertz applications.

Metal-coated polymers shaped by 3D stereolithography are introduced as a new manufacturing method for passive components for millimeter to terahertz electromagnetic waves. This concept offers increased design capabilities and flexibilities while shortening the manufacturing process of complex shapes, e.g., corrugated horns, mirrors, etc. Tests at 92.5, 140, and 170 GHz are reported.

THz-waves channeling in a monolithic saddle-coil for Dynamic Nuclear Polarization enhanced NMR.

A saddle coil manufactured by electric discharge machining (EDM) from a solid piece of copper has recently been realized at EPFL for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance experiments (DNP-NMR) at 9.4 T. The corresponding electromagnetic behavior of radio-frequency (400 MHz) and THz (263 GHz) waves were studied by numerical simulation in various measurement configurations. Moreover, we present an experimental method by which the results of the THz-wave numerical modeling are validated. On the basis of the good agreement between numerical and experimental results, we conducted by numerical simulation a systematic analysis on the influence of the coil geometry and of the sample properties on the THz-wave field, which is crucial in view of the optimization of DNP-NMR in solids.

Note: stacked rings for terahertz wave-guiding.

We demonstrate the construction of corrugated waveguides using stacked rings to propagate terahertz frequencies. The waveguide allows propagation of the same fundamental mode as an optical-fiber, namely, the HE(11) mode. This simple concept opens the way for corrugated wave-guides up to several terahertz, maintaining beam characteristics as for terahertz applications.

Redistribution of suprathermal electrons due to fishbone frequency jumps.

MHD instabilities driven by fast electrons identified as fishbonelike modes have been detected on Tore Supra during lower hybrid current drive discharges. Direct experimental evidence is reported of a novel feature: the regular redistribution of suprathermal electrons toward external tokamak regions which are correlated to periodic mode frequency jumps. Sharp drops of the electron temperature time trace are factually linked to the cyclical deterioration of the fast electron confinement.

Channeling chaos by building barriers.

Chaotic diffusion often represents a severe obstacle for the setup of experiments, e.g., in fusion plasmas or particle accelerators. We present a complete test of a method of control of Hamiltonian chaos, with both its numerical test and its first experimental realization on a paradigm for wave-particle interaction, i.e., a travelling wave tube. The core of our approach is a small apt modification of the system which channels chaos by building barriers to diffusion. Its experimental realization opens the possibility to practically achieve the control of a wide range of systems at a low additional cost of energy.

Experimental observation of nonlinear synchronization due to a single wave.

A test electron beam is propagated in a specially designed traveling wave tube. It interacts with a nonresonant wave, and its energy distribution is recorded at the tube output. We report the direct experimental observation of the spatially periodic electron velocity bunching, and of a nonlinear effect on the electron velocity modulation: the synchronization of the particles with the wave responsible for Landau damping in plasma physics. The results are explained by second order perturbation theory in the wave amplitude.

A randomized 4-arm multicenter study of interferon alfa-2b plus ribavirin in the treatment of patients with chronic hepatitis C not responding to interferon alone.

To determine whether a higher dosage of interferon (IFN) associated with ribavirin and/or prolonged time of administration may improve therapeutic efficacy, we conducted a 4-arm randomized trial on patients with chronic hepatitis C not responding to one or more previous treatment courses with IFN monotherapy. Group 1 (n = 139) received 3 million units (MU) IFN-alpha2b 3 times a week (t.i.w.) plus ribavirin 1,000 mg/d for 12 months; group 2 (n = 162) received 5 MU t.i.w. plus ribavirin for 12 months; group 3 (n = 142) received 3 MU t.i.w. plus ribavirin for 6 months; and group 4 (n = 151) received 5 MU t.i.w. plus ribavirin for 6 months. The primary end point was hepatitis C virus (HCV)-RNA clearance at the end of 6-month follow-up. HCV-RNA was negative in 15% of group 1, 23% of group 2, 11% of group 3, 16% of group 4 (group 2 vs. group 3, P =.04). Among patients with genotypes 1 and 4, sustained response was significantly higher in group 2 vs. group 3 (18% vs. 7%, P =.03; group 1 = 9%, group 4 = 12%, P = not significant [NS]). In patients with genotypes 2 and 3, sustained virologic response was not affected by the different regimens (group 1 = 32%, group 2 = 30%, group 3 = 30%, group 4 = 35%, P = NS). In conclusion, about 23% of nonresponders to IFN monotherapy may achieve a sustained response if re-treated by 5 MU t.i.w. IFN plus ribavirin 1,000 mg/d for 1 year. Patients with genotype 1 should receive a high dosage of IFN plus ribavirin for 12 months, whereas therapy for patients with genotype 2 or 3 should be less aggressive.

Severe and complicated Falciparum malaria in Italian travelers.

Imported malaria has been an important public health problem in Western countries in the last 20 years, since international travel has become an increasing habit for nonimmune populations and since chemoresistance to most antimalarial drugs has been spreading throughout the world. Moreover, immigration from African and Asian countries has been rapidly increasing, especially in Italy in the last few years. Malaria had been widespread in Italy in the past, but no new autochthonous cases have been reported since 1961. Nonetheless the number of reported cases throughout the country has been steadily growing because of imported malaria1-3 in nonimmune travelers as well as in immigrants from tropical countries. In our experience as well as according to other statistics, the vast majority of patients have Plasmodium falciparum malaria acquired in Africa.4,5 The clinical spectrum of this disease is wide, and severe cases are frequently observed, including a few fatal cases, which, although rare, are highlighted by mass media and impress the public opinion.5-8 The purpose of this study was to examine the clinical spectrum of malaria, with particular interest in severe falciparum malaria, and to define the frequency of this phenomenon and epidemiologic characteristics of patients who experience it as a life-threatening disease.

Natural beta interferon in acute type-C hepatitis patients: a randomized controlled trial.

AIM OF THE STUDY: A multicentre randomized controlled trial to assess whether a short course of beta-interferon could reduce the rate of chronic evolution of acute hepatitis C, in line with recent observations, was started in Northern Italy in 1991. METHODS: Forty acute hepatitis C patients were randomized to receive natural beta interferon 3,000,000 international units intramuscularly three times a week for 4 weeks or symptomatic drugs, and were followed up for a median period of 22.5 months. RESULTS: The chronicity rate was 75% (15/20 patients) in the interferon-treated group, and 80% (16/20) in the untreated group. No difference in the duration of the acute phase of hepatitis was observed. Hepatitis C virus ribonucleic acid was determined in 21 cases and was positive in 19 cases at baseline and in 15/17 chronic and 1/4 non chronic cases at the end of follow-up. Side effects of therapy (flu-like syndrome in 40% of cases) were mild and short-lasting. No aminotransferase flare-ups were observed during treatment. CONCLUSIONS: Beta interferon at the suggested regimen is well tolerated but does not seem to significantly influence the natural course of acute hepatitis C.

Clinical and Diagnostic Aspects of Travelers' Diarrhea due to Cyclospora Organisms.

Cyclospora sp, a recently described protozoan, is associated with prolonged self-limiting and relapsing diarrhea. The species has a worldwide distribution and a high prevalence in tropical countries. Some reports suggest that the agent is a common cause of travelers' diarrhea.

Clinical and microscopical features of small-intestinal microsporidiosis in patients with AIDS.

Intestinal microsporidiosis by Enterocytozoon bieneusi is an increasingly recognized infection in AIDS patients. We report eight cases of microsporidiosis. All patients were severely immunodepressed. Clinical features were highly variable. Patients were followed up for a mean period of 7.8 months. All patients had persistent infection during the follow-up and spore excretion remained constant. Two patients became asymptomatic during the follow-up. None of the patients presented clinical and echographic signs of biliary involvement. Treatment with albendazole, metronidazole or paromomycin failed to produce a durable clinical response or to eradicate the organism. Cases were identified by stool examination and additionally investigated with light and electron microscopy. It was found that light microscopy was a sensitive method, while electron microscopy was less sensitive but allowed the definition of the infecting species. The modified trichrome stain was a satisfactory method for diagnosis on fecal smears. The calcofluor stain and the combination of DAPI with calcofluor was a rapid and simple staining method for screening.

[Hospital costs of patients with AIDS]. / Costo ospedaliero del malato di AIDS.

We carried out a retrospective research into the hospital care cost of 52 AIDS cases we observed in our department, in the period 1984-1988. These patients required an average of 3.2 hospital admissions per year, and 101.3 hospitalization days per year, spending more than one fourth of their life span after their diagnosis of AIDS, in a hospital. The total care cost was Lit. 1,133,614,000, mostly due to the hospital stay (65.0%), but the introduction of expensive drugs will increase the cost of treatment. The average daily cost per patient was Lit. 227,900. Prognosis and cost vary according to the kind of opportunistic infection or neoplasm. The prolongation of hospitalization in consequence of social and economic problems is very frequent. A better accessibility of diagnostic systems, and a development of day-hospital and social services could reduce AIDS patients costs.