Search for magnetic monopoles with nuclear track detectors

This paper describes an experimental search for GUT magnetic monopoles in the MACRO experiment using the nuclear track subdetector CR39. After discussing the working principle, the charge resolution and the calibration of the detector, the experimental procedure for searching for magnetic monopoles is described. Since no candidates were found, the upper flux limits obtained by the MACRO CR39 used as a "stand alone detector" for magnetic monopoles of different magnetic charges are presented.Comment: 4 pages, 7 EPS figures included with epsfig, uses espcrc2.sty Talk given at the Sixth Topical Seminar on Neutrino and Astroparticle Physics, San Miniato, Italy, 17-21 May 199

Design and Modeling of an Integrated Micro-Transformer in a Flyback Converter

This paper presents the design and modeling of a square micro-transformer for its integration in a flyback converter. From the specifications of the switching power supply, we determined the geometric parameters of this micro-transformer. The π-electrical model of this micro-transformer highlights all parasitic effects generated by stacking of different material layers and permits to calculate the technological parameters by using the S-parameters. A good dimensioning of the geometrical parameters reduces efficiently the energy losses in the micro-transformer and permits to reach the desirable value of the converter output voltage. We have also simulated the electromagnetic effects with the help of the software FEMLAB3.1 in two cases. The first case, without ferromagnetic core, the second case with ferromagnetic core, in order to choose the micro-transformer that has better electromagnetic compatibility with the vicinity components. To validate dimensioning of the geometrical and technological parameters, we have simulated with the help of the software PSIM6.0, the equivalent electrical circuit of the converter containing the electrical circuit of the dimensioned planar micro-transformer

Q-balls in Underground Experiments

In this paper we present some features of Q-balls and we discuss their interactions with matter, and their energy losses in the Earth, for a large range of velocities. These calculations are used to compute the fractional geometrical acceptance of the MACRO detector. Furthermore a systematic analysis of the energy losses of Q-balls in three types of detectors is investigated. More specifically we have computed the light yield in liquid scintillators, the ionization in streamer tubes and the Restricted Energy Loss in the CR39 nuclear track detectors.Comment: 7 pages, 4 PS figures included with epsfig, uses espcrc2.sty Talk given at the Sixth Topical Seminar on Neutrino and Astroparticle Physics, San Miniato, Italy, 17-21 May 199

Design and Modeling of an Integrated Inductor in a Buck Converter DC-DC

This paper presents the design and modeling of a square inductor for its integration in Buck converter DC-DC. The first, we calculate the value of inductance. The second, we descript our inductor; dimensioning and electrical model. A buck micro converter schematic simulation coupled with ideal and integrated inductor was presented. This conceptual model of the buck is best understood in terms of the relation between current and voltage of the inductor. Finely, we have simulated the electromagnetic effects in two cases. The first case, an inductor in the air, the second case with substrate. Our geometry is created en 3D space dimension

Magnetic properties and interlayer coupling in Co/V multilayers

The magnetic properties of evaporated Co/V multilayer films have been studied by superconducting quantum interference device magnetometer and ferromagnetic-resonance (FMR). FMR has been used to study the interlayer exchange coupling and the FMR linewidth in Co/V multilayers at room temperature. Spin-waves resonance modes were observed in some Co/V multilayers and the relation of resonant field Hres with the mode number n obeys the so-called n2 law. The interlayer coupling constant was determined. The FMR linewidth, in parallel geometry, of the uniform mode was found to increase with decreasing Co thickness (10Å £ tCo £ 45Å) indicating that it corresponds to an interfacial effect

Time variations in the deep underground muon flux measured by MACRO

More than 30 million of high-energy muons collected with the MACRO detector at the underground Gran Sasso Laboratory have been used to search for flux variations of different natures. Two kinds of studies were carried out: search for periodic variations and for the occurrence of clusters of events. Different analysis methods, including Lomb-Scargle spectral analysis and Scan Test statistics have been applied to the data.Comment: 6 pages, 4 EPS figures. Talk given at the 29th ICRC, Pune, India, 3-10 August 200

A NEW APPROACH TO SYNTHESIS METHACRYLIC MONOMERS N-ALKYLMETHACRYLAMIDE USING AN ECOLOGIC AND FRIENDLY CATALYST MAGHNITE H+

In this paper, we have developed a novel procedure to synthesize four monomers formulated as 1,4-bis(Methacryloyl)Piperazine, N-Methacryloylmorpholine, N-Phenylmethacrylamide and N-Formyldimethacrylamide. N-Alkylmethacrylamide monomers are synthesized by the condensation of primary amine aniline and formamide or heterocyclic secondary amines such as piperazine and morpholine with methacrylic anhydride using an ecologic and friendly catalyst “Maghnite H+”, a proton exchanged montmorillonite clay by replacing a toxic reactant acryloyl chloride and triethylamine which are using in previously published studies. This new approach is even more interesting since this synthesis is carried out in bulk (without solvent) and at 0 °C for 2 hours, obtaining a better yield around 70% and selectivity to the product 100%. These monomers are characterized and confirmed by Infrared Spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy

Volvulus du grêle sur mésentère commun incomplet une redoutable complication rare chez l’adulte: à propos de 1 cas

Le mésentère commun résulte d'une anomalie de rotation du tube digestif. Il est caractérisé par la persistance d'une disposition anatomique embryonnaire secondaire à une anomalie de rotation de l'anse ombilicale primitive, constituant ainsi un méso commun à toute l'anse intestinale etune racine du mésentère extrêmement courte. Cette insuffisance de rotation est le plus souvent associée à un défaut d'accolement. Ces  anomalies de rotation intestinale peuvent aboutir à des complications redoutables parfois mortelles, qui surviennent généralement au cours de la période néonatale où à l'âge pédiatrique. On estime que la prévalence de ces malformations congénitales à l'âge adulte est de l'ordre de 0,2% à 0,5% âge auquel elles demeurent très souvent asymptomatiques et donc non diagnostiquées. Le diagnostic de volvulus total du grêle peut se faire dans des circonstances très variées: en urgence devant un tableau  d'occlusion intestinale aiguë, voire un état de choc pouvant conduire au décès, devant un tableau de douleurs abdominales répétées plus ou moins associées à des troubles du transit. Nous rapportons l'observation d'un patient de 18 ans admis pour volvulus total du grêle sur mésentère commun incomplet chez qui l'évolution était favorable