Quantum Critical Ferromagnetism in Ni x Pd1- x Alloys

We analyze the non-Fermi liquid behavior in the proximity of the quantum phase transition induced by the strong polarization of the electrons due to local magnetic moments in Ni _x Pd_1-x alloys. We use the renormalization group approach introduced by Hertz–Mi11is–Moriya (HMM) to estimate the temperature dependence of the electrical resistivity for the case of three dimensional itinerant ferromagnets. We study two different cases, namely, the clean and disordered ferromagnets, and argue that at the present time more experimental data are needed to decide if the HMM theory can accurately describe the physical properties in Ni _x Pd_1-x alloys.     

The renin-angiotensin system and the effect of propranolol upon the cerebral cortical and hypothalamic circulation in hypoxia

The regulatory mechanisms of the cerebral blood flow have preoccupied the physiology department of Cluj since the end of the 4th decade. These studies continued over the last years. The researches progressed from the studies of regulation by blood pressure changes to the nervous regulation and to the metabolic one. This paper's subject is the renin-angiotensin and adrenalin system influence on the changes of cerebral blood flow during the general hypoxic hypoxia and cephalic ischemia. Experiments were performed in 10 dogs anaesthetised with a mixture of chloralose, urethan and morphine. Hypoxic hypoxia was obtained by breathing a mixture of 11% oxygen in nitrogen, in a closed system and cerebral ischemic hypoxia by partial compression of the carotid arteries, after the ligation of the vertebral and thyroid arteries. The arterial blood pressure and the cerebral and hypothalamic blood flow, measured with the heated thermoelement, were registered. The plasma renin activity was tested radioimmunologically before, at 1.5 min, 5, 10 and 15 min, after the beginning of hypoxia. In ischemic hypoxia the experiment was repeated after venous perfusion with propranolol (0.6 mg/kg/h). The systemic blood pressure increased in both forms of hypoxia. The cortical and hypothalamic blood flow increased with the systemic arterial blood pressure. The hypothalamic blood flow remained stable or diminished a little. Propranolol increased the cerebral blood flow during ischemic hypoxia up to 300%. The i.v. administration of angiotensin (1-5 mg/kg) increased the cortical flow, while the hypothalamic flow remained self-regulated. Plasma renin activity increased more in general hypoxic hypoxia, than in cephalic ischemic hypoxia. After propranolol the increase was higher in this hypoxia. Propranolol produced a major activation of the renin-angiotensin system and of the cortical blood flow in ischemic cephalic hypoxia, the renin-angiotensin system being located in the cerebral structure. As well high doses of angiotensin produced cerebral vasodilatation in small cerebral vessels. This effect was found in our experiments in the cortical blood flow too. Our results indicate a beneficial propranolol effect on cortical circulation in ischemic hypoxia.     

Algorithmic mechanism design for load balancing in distributed systems

Computational grids are promising next-generation computing platforms for large-scale problems in science and engineering. Grids are large-scale computing systems composed of geographically distributed resources (computers, storage etc.) owned by self interested agents or organizations. These agents may manipulate the resource allocation algorithm in their own benefit, and their selfish behavior may lead to severe performance degradation and poor efficiency. In this paper, we investigate the problem of designing protocols for resource allocation involving selfish agents. Solving this kind of problems is the object of mechanism design theory. Using this theory, we design a truthful mechanism for solving the static load balancing problem in heterogeneous distributed systems. We prove that using the optimal allocation algorithm the output function admits a truthful payment scheme satisfying voluntary participation. We derive a protocol that implements our mechanism and present experiments to show its effectiveness.     

On the simulation of a corona discharge by the similarity theory methods

A general system of equations for a corona discharge has been derived and reduced to a dimensionless form using the methods of the similarity and dimension theory. Criteria and conditions for the similarity of the processes occurring during a corona discharge have been determined. Formulas for free space-charge density have been derived; the classical structure of the current-voltage characteristic for an arbitrary system of electrodes has been confirmed by different methods: using the theory of similarity, analyzing self-similar solutions, approximating the field distribution, and averaging the equation for the current density with respect to the volume of the interelectrode gap. It has been shown that the quadratic pattern of the current-voltage characteristics of the corona discharge results from the linear dependence of the electric field intensity and the linear threshold dependence of the density of free space carriers on the voltage.     

Heat transfer at electrohydrodynamic pumping through in an evaporator-condensing system

The article considers the hydrodynamic and temperature dependencies of heat and mass transfer in an evaporator-condensing system representing a pulsating heat pipe with a built-in heater used as an evaporator, a vapor condenser, and an electrohydrodynamic pump for forced pumping through of a coolant. The influence of the electric current intensity and voltage on the electrohydrodynamic pump, the applied power, the temperature head, and other factors on the heat transfer has been investigated in order to reveal the physical peculiarities of the processes under investigation and the creation of a background for their calculation. An electric field is used only in the electrohydrodynamic pump, which is situated outside of the evaporator and condenser. The experimental data are treated in the form of “rectified” dependencies having a generalized character between the dependent and governing parameters of the process. The obtained results can be used for in-depth investigations, as well as for the design and fabrication of cooling and compact thermostabilizing electrohydrodynamic devices.     

Unconventional method used in synthesis of polyphosphoesters

Polyphosphonates, polyphosphates, polyarylazophosphonates and polyarylazophosphates were synthesized by a new alternative to the classical phase transfer catalysis, respectively, the modified inverse phase transfer catalysis (IPTC) polycondensation of various phenylphosphonic (phosphoric) dichlorides (phenylphosphonic dichloride, phenylphosphoric dichloride, p-chlorophenylphosphoric dichloride) with bisphenols: bisphenol A, tetrabromobisphenol A, bis-(4-hydroxyphenyl)methane (bisphenol F), 4,4′-dihydroxyazobenzene. The polymers were characterized by infrared spectroscopy and magnetic resonance (¹H-NMR, ³¹P-NMR, ¹³C-NMR) spectroscopy. Yields in the range of 63.5–85% and molecular weights (M _w) of ~2,000–8,200 g mol^?1 were obtained. Polyphosphonates were stable up 210–270 °C and polyphosphates up 190–220 °C in air atmosphere. For a correct estimation of the thermal behavior of similar compounds, a kinetic analysis using a modified version of Non Parametric Kinetic method for representative polyphosphonate and polyphosphate was realized. The studies made on the hydrolytic degradation of the synthesized polyphosphates show that the most stable polymer under alkali-catalyzed degradation is the polyphosphate obtained by IPTC of phenylphosphoric dichloride and bisphenol A.     

Electrical filtration of dielectric liquids from semiconducting and conducting particles

Certain problems of electrical purification of dielectric oils (for example, transformer oil) to remove micron-sized semiconducting and conducting particles are considered. A solution of the problem concerning the dependence of the particle concentration on the time in the output of an electrofilter both at a zero and a nonzero flow rate is given. It is shown that, in both cases, the mathematical structure of the solutions is the same. Thus, it is possible to use the same formulas with the parameters of the given mode. Physical and mathematical interpretations of the experimental results are proposed. Equations for the theoretical dependences corresponding to the experimental ones are obtained and their graphs are plotted. The experimental data, which are in good agreement with the theoretical results, are generalized using dimensionless logarithmic equations.     

Electroconvective rotation of a dielectric liquid in external electric fields

The rotational electroconvective motion of liquid dielectrics in an ordinary and in two crossed electric fields is considered from the point of view of the action of the mechanical moments on the liquid. The main peculiarities of the polarization of ideal, nonideal, and poor conducting dielectrics are found. The problems concerning the rotation of the liquid in the crossed fields are solved, and the known experimental results on water film rotation in such fields are explained.     

Open-Source Model Checking

We present GMC², a software model checker for GCC, the open-source compiler from the Free Software Foundation (FSF). GMC², which is part of the GMC static-analysis and model-checking tool suite for GCC under development at SUNY Stony Brook, can be seen as an extension of Monte Carlo model checking to the setting of concurrent, procedural programming languages. Monte Carlo model checking is a newly developed technique that utilizes the theory of geometric random variables, statistical hypothesis testing, and random sampling of lassos in Büchi automata to realize a one- sided error, randomized algorithm for LTL model checking. To handle the function call/return mechanisms inherent in procedural languages such as C/C++, the version of Monte Carlo model checking implemented in GMC² is optimized for pushdown-automaton models. Our experimental results demonstrate that this approach yields an efficient and scalable software model checker for GCC.