The effects of growth hormone in children with a GH deficiency: a report of 5 cases

The authors describe 5 cases, 3 boys and 2 girls, with idiopathic growth hormone deficiency in prepubertal age, treated with human growth hormone. In four of five cases the response to treatment with GH was relevant. Only in one case (F1) the response was negative. The results of this study confirm that rhGH is a safe and effective therapy in children with GHD.     

New method for assessing the global quality of energy systems

Comparisons of various energy systems are often made from partial, limited standpoints that do not take into due consideration the numerous factors involved in such systems. A more complete assessment of the global quality of energy systems must consider a wider range of characteristics, such as: conversion and transportation yields, energy potential, added value, risk of accidents during conversion and transportation, coefficients of transportability and storability, and polluting emissions (carbon monoxide, carbon dioxide, sulphur and nitrogen oxides, unburnt hydrocarbons, dust, radionuclides and dispersed heat).

This paper not only identifies and quantifies the parameters that allow the above qualities to be expressed, but also defines a tree-structured energy-quality index system which starts from the parameters identified and makes it possible to obtain a global summary index, through various intermediate levels of aggregation.

Our objective is to make an instrument available to professionals (engineers, policymakers and energy managers) which allows them to concentrate their attention each time, according to the specific needs in question, on particular aspects of the quality of the energy, or to obtain numerical indicators that briefly express quality in the broadest sense.

In addition, a sample application of the proposed method is presented, using data gathered mainly from the literature on alternative systems for power production and space heating by fossil fuels.     

Behavior of a vibrating wire near the liquid3He-vacuum interface and in a saturated3He-4He mixture

In this paper we describe the effect of the vicinity of a liquid³He-vacuum interface on the behavior of a vibrating wire viscometer. It was found that in the fluid near the liquid interface the quality factor is lower than in the bulk liquid. We further report on the observation of a doubling of the resonance peak of the wire in a saturated³He-⁴He mixture. The frequencies and amplitudes of the two peaks strongly depend on the distance between the phase boundary and the vibrating wire; the temperature and the velocity of the phase boundary have no significant influence on the peak frequencies. The observed peak doubling is attributed to the coupling of the vibrating wire with a standing second-sound wave in the dilute phase where the volume of the dilute phase can be regarded as a resonating cavity for second sound.     

The use of stokeslets to describe the arbitrary translation of a disk near a plane wall

A previously presented method is extended to describe the fully three-dimensional Stokes flow generated by the translation in any direction of an arbitrarily oriented disk in fluid bounded by a plane wall. The velocity field is represented solely in terms of stokeslet distributions on the disk, modified to take account of the bounding wall according to the century-old idea of Lorentz. Sets of integral equations of the second kind, not all disjoint, are obtained for the Abel transforms in each Fourier mode of the density functions. However, only a few modes need be considered in determining the flow field to order D ^-3, where D is the distance of the disk axis from the wall. Less detail is required to evaluate the drag force and torque experienced by the disk.     

Uniform temperature cooling power of the superfluid Stirling refrigerator

Uniform temperature cooling power measurements of a superfluid Stirling refrigerator are presented for³He-⁴He molar concentrations of 5.9%, 17% and 36% and for temperatures between 0.37 K and 1.4 K. The results are compared to an ideal Fermi gas model and to a more general thermodynamic model. The Fermi model agrees well with the 5.9% concentration data; however, the more elaborate model is needed for higher concentration mixtures.     

A behavioral approach to linear exact modeling

The behavioral approach to system theory provides a parameter-free framework for the study of the general problem of linear exact modeling and recursive modeling. The authors present the solution of the (continuous-time) polynomial-exponential time series modeling problem. Both recursive and nonrecursive solutions are provided and classified according to properties like complexity and controllability. It is shown, in particular, that recursive modeling corresponds to updating by means of a cascade inter-connection of systems. As a special case, the solution of several other problems, such as rational interpolation, realization, and modeling of arbitrary discrete-time time series, is obtained     

Stabilization of uncertain boundary control systems

We consider a class of linear infinite-dimensional systems subject to boundary uncertainties, which are linear and time-invariant. Using a deterministic approach to the design of stabilizing feedback controls, uniform exponential stability of the zero state is achieved. Lyapunov techniques are combined with Datko or Ichikawa theory. Three illustrative examples are presented.     

Nitric oxide reduction and carbon monoxide oxidation over carbon-supported copper-chromium catalysts

Carbon supported copper-chromium catalysts are shown to be very active for both the reduction of nitric oxide with carbon monoxide and the oxidation of carbon monoxide with oxygen. Mixed copper-chromium oxide active phases have good activity in the simultaneous removal of nitric oxide and carbon monoxide from exhaust gases. The influence of several catalyst variables has been investigated. The activity per volume of catalyst increases with increasing loading, while the intrinsic activity shows a maximum around C/M=100−50. An optimum catalyst for nitric oxide reduction and carbon monoxide oxidation has a copper/chromium ratio of 2/1. The apparent activation energy for the carbon monoxide oxidation over carbon supported copper-chromium catalysts is 77 kJ/mol, suggesting that the Cu---O bond rupture is the rate-limiting process. The reduction of nitric oxide takes place at higher temperatures. Since all catalysts have a low selectivity for molecular nitrogen formation at lower temperatures, the dissociation of nitric oxide is probably rate determining, resulting in a slightly reduced catalyst system. In an excess of carbon monoxide the reaction is first-order in nitric oxide and zero-order in carbon monoxide. Moisture inhibits the reaction by reversible competitive adsorption, whereas carbon dioxide does not. Oxygen completely inhibits the reduction of nitric oxide due to the more rapid reoxidation of the catalytic sites compared to nitric oxide. Therefore, the reduction of nitric oxide takes place only when all oxygen has been converted and, hence, is shifted to higher temperatures. As a possible consequence, the production of nitrous oxide is reduced. Nitric oxide and molecular oxygen react preferentially with carbon monoxide, so, in an excess of oxidizing component, gasification of the carbon support occurs at higher temperatures after carbon monoxide has been completely consumed.     

Structural and chemical analysis of C : H,O /Si : H,O multilayers deposited by reactive RF sputtering

Hydro-oxygenated carbon (C : H,O) and silicon (Si : H,O) layers are deposited by RF sputtering of graphite and silicon targets in a mixture of argon, hydrogen and oxygen gases. C : H,O/Si : H,O/C : H,O/Si : H,O... multilayers are obtained by sequential deposition of C : H,O and Si : H,O layers. Infrared (IR) spectroscopy, Grazing Incidence X-ray Diffraction (GIXD) and X-ray Photoelectron Spectroscopy (XPS) techniques have been used to analyse the formed multilayers. The IR spectra made on as deposited structures show the presence of Si---C, Si---O, C---O, Si---H, C---H and C=C bonds. This result indicates an interfacial reactivity between Si : H,O and C : H,O layers. The latter result is confirmed by the XPS measurements. After an annealing at 850°c for two hours under argon atmosphere (10^-3 mbar), the concentration of the Si---C bonds is increased by a factor two while the Si---H and C---H bonds disappear complet The GIXD measurements show that the multilayers are amorphous when annealed below 750°C, and they are crystallized with the formation of the α-SiC phase if the heat treatment is made at 850°C. The mean size of the microcrystallites is 50 Å about.