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A 3D model for the simulation of inductively coupled plasma torches (ICPTs) working at atmospheric pressure is presented, using a customized version of the computational fluid dynamics (CFD) commercial code FLUENT®. The induction coil is taken into account in its actual 3D shape, showing the effects on the plasma discharge of removing the axisymmetric hypothesis of simplification, which characterizes 2D approaches. Steady flow and energy equations are solved for optically thin argon plasmas under the assumptions of local thermodynamic equilibrium (LTE) and laminar flow. The electromagnetic field equations are solved on an extended grid in the vector potential form. In order to evaluate the importance of various 3D effects on calculated plasma temperature and velocity fields, comparisons of our new results with the ones obtainable from 2D models and from an improved 2D model that includes 3D coil effects are presented. 3D results are shown for torches working under various geometric and operating conditions and with different coil shapes, including conventional helicoidal, as well as planar, elliptical, and double-stage configurations.

We report a case in which life support for cardiogenic shock was achieved by a nonpulsatile venoarterial bypass, and left ventricular decompression was obtained by a catheter placed percutaneously through the aortic valve into the left ventricle. The blood drained from the left ventricle was pumped into the femoral artery. The normalization of left heart filling pressures allowed the resolution of pulmonary edema, and the patient underwent a successful heart transplantation following 7 days of mechanical cardiocirculatory support.

Abstract:: The paper deals with the time-dependent numerical simulation of inductively-coupled plasma torches during the ignition transient, which is induced by a graphite rod and leads to the final, self-sustaining plasma condition. The study has been performed by using a 2D time-dependent fluid-magnetic code based on the SIMPLER algorithm within the assumptions of laminar flow, local thermodynamic equilibrium conditions and optically thin plasma. The graphite rod has been treated as a real obstacle for the gas and the electron emission due to the thermoionic effect has been suitably taken into account. The advantage of using a time-dependent code in order to select different plasma operating conditions that can lead to stable discharges is pointed out. Results for both argon and air discharges are presented for different torch geometries, RF frequencies and inlet gas configurations (also including the presence of a carrier gas injected along the axis of the torch). Moreover, the final self-sustaining plasma configurations obtained are compared, when available, with results coming from static models, which have been published by other authors.

Summary In this paper we present a product quadrature rule for the discretization of the well-known linear transport equation in slab geometry. In particular we give an algorithm for constructing the weights of the rule and prove that the order of convergence isO(n-3+d), d>0 small as we like. Numerical examples are given, and our formula is also compared with product Simpson rules. Finally, we examine a Nyström method based on our quadrature.

Linear forced oscillations in a Vlasov plasma are studied using a recently proposed model that generalizes the classic theory of Debye shielding through a space integro-differential equation for the amplitude of the oscillating electric potential. The equation involves a second order space differential operator and an integral term whose kernel depends on ion and electron equilibrium distributions. The integro-differential equation is solved by means of a synthesis method, similar to the techniques usually employed in neutron transport. The kernel of the integral term is split in two parts; the first is a diffusion-like kernel, approximating the exact one, while the second plays the role of a remainder term, to be iterated according to a synthesis scheme. The diffusive kernel contains a free complex parameter, whose optimum value is to be searched in order to accelerate the convergence of the method. The performance of the method is discussed, and results in physically significant cases are shown.

1. An adenosine triphosphatase membrane system, dependent on Mg2+ and activated further by Na++K+, was prepared from goldfish anterior intestine by differential centrifugation of homogenized intestinal scrapings. 2. The affinity of this preparation for Na+ in the presence of K++Mg2+, for K+ in the presence of Na++Mg2+ and for Mg2+ alone, measured at 37°, did not depend on the previous environmental temperature of the fish. When Na++K+ were added to preparations from 8°-acclimatized fish the affinity for Mg2+ increased; this was not seen with preparations from 30°-acclimatized fish. 3. Part of the Mg2+-activated adenosine triphosphatase was inhibited by Na+ and the amount of inhibition appeared to increase at high acclimatization temperatures. 4. This Na+-inhibited adenosine triphosphatase was separated from the (Na++K+)-activated enzyme by centrifugation on sucrose density gradients. 5. Preparations from 8°-acclimatized fish contained less Mg2+-activated and more (Na++K+)-activated adenosine triphosphatase than did similar fractions from 30°-acclimatized fish. 6. Acclimatization to different environmental temperatures might involve one form of adenosine triphosphatase changing to another. The origin of various membranes seen in microsomal fractions must, however, be established before this hypothesis can be tested further.

Transmission and scanning electron microscopy indicate that rabbit platelets incubated in protein-poor medium retain their reactivity to shape change-inducing agents such as 5-hydroxytryptamine, adenosine-5′-diphosphate and chlorpromazine. Such platelets may be used as models for drug-membrane interactions, e.g. in neuronal cells.

Myelin basic protein (MBP) isolated from bovine spinal cord caused a marked shape change reaction of human blood platelets which was not accompanied by the release reaction and not inhibited by methysergide and spiroperidol. Only those basic proteins, including MBP, which had previously shown to exert neuronal depolarisation also induced the shape change reaction. Therefore, these findings may extend the use of platelets as neuronal models.

Several cases of human rickettsiosis caused by Rickettsia parkeri were recently documented in the Parana´ River delta of Argentina, where the tick vector is Amblyomma triste Koch. As cattle suffer recurrent A. triste infestations, they are at risk of becoming infected with R. parkeri. Herein we investigated the dynamics of R. parkeri and its A. triste vector in a herd of beef cattle. Cattle were followed for 18 mo and samples were analyzed for the presence of antibodies against four Rickettsia species (R. parkeri, Rickettsia bellii, Rickettsia amblyommii, and Rickettsia felis) and also for the presence of rickettsial DNA. Additionally, cattle were examined for attached ticks and questing adult ticks were collected. All ticks were analyzed for the presence of rickettsial DNA. No evidence of rickettsemia was found in any cow, but the high R. parkeri infection rate documented in A. triste both questing in the study area (13.9%) and feeding on cattle (19.8%) and the identification of antibodies against R. parkeri antigen in 90% of cattle are evidence that infection is taking place. Altogether, our data suggest that A. triste ticks are capable of naturally exposing cattle to R. parkeri. However, the progress of R. parkeri infection and its impact on bovine health and production remain to be established.