Adding an integrator for the stabilization problem

We study the relationship between the following two properties: P1: The system is locally asymptotically stabilizable; and P2: The system is locally asymptotically stabilizable; where . Dayawansa, Martin and Knowles have proved that these properties are equivalent if the dimension n = 1. Here, using the so called Control Lyapunov function approach, (a) we propose another more constructive and somewhat simpler proof of Dayawansa, Martin and Knowles's result; (b) we show that, in general, P1 does not imply P2 for dimensions n larger than 1; (c) we prove that P2 implies P1 if some extra assumptions are added like homogeneity of the system. By using the latter result recursively, we obtain a sufficient condition for the local asymptotic stabilizability of systems in a triangular form.     

Chronic hepatitis C in hemodialysis patients

Hepatitis C virus (HCV) is an important cause of chronic hepatitis in dialysis patients. With regard to epidemiology, the time on haemodialysis, the (previous) use of intravenous drugs as well as the number of blood transfusions received are important risk factors. There are strong indications suggesting nosocomial transmission of HCV. Strict application of infection prevention procedures in haemodialysis units is mandatory to restrain spread of HCV infection. Preliminary results show equal efficacy of alpha-interferon in normalisation of serum transaminases in dialysis patients and in patients with normal kidney function. However, in both groups relapses occur often, despite induction of remission. Antiviral therapy (with interferon and ribavirin) is emerging as a valid option to induce HCV eradication in dialysis patients. Thereafter, transplantation may be considered.     

Gaussian Fitting Parameters of the ESA PLANCK HFI Beams

We present Gaussian fitting parameters of simulated beams of the High Frequency Instrument (HFI) of the ESA PLANCK mission. This space probe is designed for measuring the anisotropy of temperature and polarization of the Cosmic Microwave Background (CMB). The six HFI spectral bands cover the frequency range 0.1 - 1 THz with 52 bolometers. Their beams are computed by multi-mode physical optics propagation of the source field from the apertures of the horns simulated by the scattering matrix approach. Computed power patterns are fitted by the elliptical Gaussian beams minimizing the peak difference between the two power distributions within the beam. This approximation is generally considered as acceptable from the scientific viewpoint, although we show that induced errors are far from negligible.     

A disaggregate econometric analysis of electricity distribution capital costs

Under the assumption that electric utilities minimize their capital, labor, and electric losses costs in each local distribution system, capital input demand functions are developed at a highly disaggregated level and econometrically estimated, using cross-sectional data on 55 communities served by Long Island Lighting Company. These functions are then used to clarify such policy issues as the allocation of joint capital costs on the basis of marginal costs, the existence of economies of scale and density, and the appropriateness of natural monopoly status for electricity distribution.     

Circulating IgA-immune complexes in Henoch-Sch?nlein purpura. A longitudinal study of their relationship to disease activity and vascular deposition of IgA

In Henoch-Sch?nlein purpura immune complexes in inflamed vessel walls characteristically contain immunoglobulin A(IgA). To determine whether IgA is also the predominant immunoglobulin in circulating immune complexes, we compared the results of three immune complex assays with specificities for different classes of immunoglobulins in a longitudinal study of 37 patients (30 children and seven adults) with Henoch-Sch?nlein purpura. Circulating IgA-containing immune complexes were detected by their reactivity with a low avidity anti-IgA antibody in 27 of the 37 patients. IgA was simultaneously present in cutaneous vessel walls in 95 percent of the patients with circulating IgA-containing immune complexes. High levels of IgA-containing immune complexes were found only during the initial phase of the disease. Immune complexes containing bound complement breakdown products were demonstrated by binding to conglutinin. IgA was found in these immune complexes in 17 patients, IgG in 17 and IgM in nine patients. There was no apparent relation with the class of immunoglobulin in the deposits. Conglutinin-binding immune complexes were present later in the course of the disease and after remission. C1q-binding immune complexes were only found in two patients. These findings suggest that immune complexes-containing IgA may initiate the vasculitis of Henoch-Sch?nlein purpura, whereas complement-reacted immune complexes containing immunoglobulins of the other classes appear in the circulation in a later phase.     

On the stabilization of controllable and observable systems by an output feedback law

For control systems which can be locally stabilized in small time by means of a dynamic periodic time-varyingstate feedback law, we give a sufficient condition on Lie derivatives of the output for local stabilization in small time by means of a dynamic periodic time-varyingoutput feedback law. If the system is analytic our sufficient condition is also necessary.     

Transvenous kidney puncture. New procedure for withdrawal of kidney tissue

A transvenous catheter technique for renal puncture is described which was successful in 9 of 11 punctures performed in 8 dogs. Macrohematuria was not observed in any case. Autopsy revealed only small subcapsular hematomas. The advantage of this procedure is the reduced risk of bleeding achieved by peripheral puncture and by-passing of the great central vessels with aid of phlebographic controls. Moreover localization of kidneys by excretion urography--impossible in patients with renal insufficiency--is unnecessary.     

Fluorine motion in PbF2: Fe3+ studied by ESR

The Fe³⁺ ion is used as an ESR probe to detect the mobility of the F^? ions in the superionic conductor PbF₂. At room temperature the ESR spectrum is characterized by a superhyperfine structure with ¹⁹A = 22 G. At rising temperature the s.h.f. structure collapses due to vacancy-diffusion with a hopping rate of about 4.10⁸.s^?1.