Analysis of the booster DC to DC converter with feedback

The field effect power transistors are used in many applications in electromechanical systems. Control of the field effect power transistors requires isolated 5V control signals and isolated 12V DC sources. The first problem is resolved by using optical pairs: light emitting diodes with phototransistors. The second problem can be resolved by using impulse voltage sources. The primary coil of a transformer is connected to the battery by a transistor switch. In the first period of operation of this voltage source, the energy is stored in the magnetic field of transformer’s inductance. In the second period, the energy is delivered to the output voltage source. Energy is delivered from the secondary transformer’s coil to the output capacitor through a diode. As a rule, one separate voltage source has a small power, that is why one impulse voltage source can have the necessary number of isolated output voltage sources, i.e., 3, 6, 9, 12, etc So, we can design an impulse DC to DC voltage source with multiple isolated output voltage sources. By changing the charge time of the inductor, we can control the output voltage by using negative feedback proportional to the output voltage and / or a current. In the report, different variants of impulse voltage sources are considered, with analog base elements and on the base of microprocessors. Analyses operation of these impulse voltage sources enable us to determine the period (frequency) of internal operation with ordered maximum transformer efficiency values. The concept of controlled impulse voltage sources is very important because these sources are very simple. They are reliable and have high level of electrical isolation

On the Mathematical Simulation of the Measuring of the Intraocular Pressure by Maklakov Method

Maklakov’s method for measurement of the intraocular pressure (IOP) is based on approach, in which an eyeball is modeled as a thin-walled spherical liquid-filled shell. Measuring the IOP one estimates the diameter of the circular contact area of the cornea and the tonometer. In the clinic special tables are used to estimate the IOP relating to the measured diameter. However nowadays the calculating of such tables is based on the empirical values of the IOP. In the present paper the mathematical simulation of the measuring of the intraocular pressure by Maklakov method is considered

Variations of cosmic rays according to the data of interplanetary probes Zond-3 and Venus-2

Cosmic ray intensity variation measured by Zond 3 and Venus 2 interplanetary probe

New weapons in the war on malaria : halting the disease is crucial to improving overall health in Tanzania

French version available in IDRC Digital Library: Nouvelles armes dans la guerre contre le paludisme : éradiquer la maladie pour améliorer la santé générale en TanzanieEvidence showing the large impact of malaria on Tanzanians’ health has provided the impetus for significant policy changes on how to treat and prevent the disease across the country. The fight against malaria is now proceeding on many fronts, from preventative measures such as the promotion of insecticide-treated bednets to the introduction of more effective treatments, such as new drug therapies

Quantum interference effects of γ radiation under crossing-anticrossing of nuclear levels in an RF field

The quantum interference effects occurring in resonant scattering of a γ photon in the multilevel γ-optical medium 57Fe, affected by an external RF field, have been theoretically investigated. It is shown that a significant reconstruction of the hyperfine structure of nuclear states leads to the interference of partial forwardscattering amplitudes of a γ photon and, therefore, to a significant change in the nuclear refractive index of the γ-optical medium, depending on the amplitude, frequency, and phase of the external RF field. The conditions are found under which the effect of electromagnetically induced transparency can be observed in the technique of in-phase detection of γ photons. © Allerton Press, Inc. 2007

Analysis of vibration impact on stability of dewetting thin liquid film

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description is reasonable and the amplitude equation holds. The linear and nonlinear analyses of the amplitude equation and the numerical computations show that such vibration stabilizes the film against dewetting and rupture.Comment: 19 pages, 11 figure

Coherent influence of RF field on the gamma-optical properties of a medium upon crossing-anticrossing of nuclear levels

A new approach to the observation of electromagnetic-induced transparency in gamma optics is proposed. For this purpose, the propagation of a resonant gamma photon in a 57Fe magnetic medium affected by an external radiofrequency (RF) field is considered. It is demonstrated that, in the case of crossing-anticrossing, a resonant RF field significantly transforms gamma-optical properties of the medium that become dependent on its parameters. This allows coherent control of the group velocity of gamma photons and controlled filtering of unpolarized gamma radiation in the sample to be realized. © Nauka/Interperiodica 2007

Dark matter and structure formation a review

This paper provides a review of the variants of dark matter which are thought to be fundamental components of the universe and their role in origin and evolution of structures and some new original results concerning improvements to the spherical collapse model. In particular, I show how the spherical collapse model is modified when we take into account dynamical friction and tidal torques

Neutral Particles in Light of the Majorana-Ahluwalia Ideas

The first part of this article (Sections I and II) presents oneself an overview of theory and phenomenology of truly neutral particles based on the papers of Majorana, Racah, Furry, McLennan and Case. The recent development of the construct, undertaken by Ahluwalia [{\it Mod. Phys. Lett. A}{\bf 9} (1994) 439; {\it Acta Phys. Polon. B}{\bf 25} (1994) 1267; Preprints LANL LA-UR-94-1252, LA-UR-94-3118], could be relevant for explanation of the present experimental situation in neutrino physics and astrophysics. In Section III the new fundamental wave equations for self/anti-self conjugate type-II spinors, proposed by Ahluwalia, are re-casted to covariant form. The connection with the Foldy-Nigam-Bargmann-Wightman- Wigner (FNBWW) type quantum field theory is found. The possible applications to the problem of neutrino oscillations are discussed.Comment: REVTEX file. 21pp. No figure

Effect of short PSG peptide fragments on the cytokine profile in Wistar rats during allogeneic transplantation <i>in vivo</i>

Pregnancy-specific beta-1-glycoprotein (PSG) is a protein with pleiotropic biological effects, particularly immunoregulatory and immunosuppressive potential. The use of recombinant PSG may exert therapeutic effects in experimental animals with induced autoimmune diseases. Recently, a search for the biological effects of short linear motifs (SLiMs) has become a new strategy for designing the pharmacological compounds. Tetrapeptide regions have been identified in the primary structure of several PSGs: YQCE, YECE and YACS, these SLiMs exhibit immunomodulatory activity. The aim of our study was to evaluate the prospectives for usage of PSG peptide fragments as pharmacological agents to modulate transplant immunity. We used an original model of host-versus-graft response in male Wistar rats transplanted with bone marrow, without prior conditioning treatment of recipients. We used a cocktail of the PSG peptide fragments administered to Wistar rats in the course of allogeneic bone marrow transplantation (BM) in dynamic manner, evaluating the cytokine profile as an integral index of immune response. Cytokine levels were determined by multiplex method using Bio-Plex ProTM Rat 23-Plex kit. Statistical processing of the data was performed by means of two-way analysis of variance and Tukey’s post hoc test for multiple comparisons. We have found that the levels of pro-inflammatory cytokines (IFNγ, IL-1α, IL-1β, IL-18), as well as the contents of G-CSF, GM-CSF and IL-7 were increased in the animals injected with BM only. In the group of animals injected with BM + PSG peptides, an increase in IFNγ, IL-6, TNFα was observed, which decreased by the end of the experiment. Increased levels of antiinflammatory cytokines IL-4 and IL-13 were detected in blood serum of the animals on day +14. Moreover, administration of PSG peptides also led to increase in IL-2, M-CSF, MCP-1, and RANTES levels on day 14 from the beginning of the experiment, and to a gradual decrease in their levels till the end of the experiment. Meanwhile, control group showed a marked tendency for increase of these and other cytokines. Thus, it was shown that the use of PSG peptides upon development of immune response to BM allograft may promote a return to normal levels for the most cytokines studied, thus presuming the immunopharmacological potential of these peptides. The obtained data can be used to develop a pharmacological preparation of the studied peptides to correct the imbalance of immune system