681 research outputs found

    Could we learn more about HERA high Q2Q^2 anomaly from LEP200 and TEVATRON? R-parity violation scenario

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    The excess of high Q2Q^2 events at HERA reported in the early 1997 by H1 and ZEUS collaborations has become the subject of extensive studies in the framework of several models related to new physics. Here we concentrate on the most promising, from our point of view, model describing HERA anomaly. We update our previous analysis and take into account new HERA statistics of the 1997 year. HERA events are considered within the R-parity broken SUSY model for a specific scenario with several non-zero couplings. R-parity broken SUSY with several non-zero couplings could explain both high Q2e++jetsQ^2 e^+ + jets and μ++jets\mu^+ + jets observed at HERA. The consequence of such a particular scenario is the excess of high Q2Q^2 di- or tri-jet events at HERA. The relation of this scenario for LEP and TEVATRON colliders is considered. This study shows that if a squark resonance does take place at HERA, supersymmetry with broken R-parity can be revealed at either LEP200 or TEVATRON in the near future.Comment: 15 pages, LaTeX file with 9 eps figure

    Analysis of the booster DC to DC converter with feedback

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    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

    Minimal Supersymmetric Standard Model within CompHEP software package

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    The Minimal Supersymmetric Standard Model is presented as a model for the CompHEP software package as a set of files containing the complete Lagrangian of the MSSM, particle contents and parameters. All resources of CompHEP with a user-friendly interface are now available for the phenomenological study of the MSSM. Various special features of the model are discussed.Comment: 11 pages, LaTeX, submitted to Comp. Phys. Communicatio

    Development of a method of electrodeposition of non-ferrous metals on a rotating cathode covered with gallium

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    Electrodeposition of copper and nickel from acidic solutions using a rotating cathode coated with liquid and solid gallium has been studied. Methods of nonferrous metals separation from the gallium coating of the cathode were determined. Electrodeposition on the liquid gallium coating was carried out at a temperature of 50 °C. Separation of metals from gallium was performed by alkaline treatment. On the solid gallium cathode coating, electrodeposition was performed at 25 °C. The metal precipitates were separated from the cathode after it was heated. When using cathode with hard gallium coating the reduction of electric power consumption for copper by 85 % and for nickel by 15 % was obtained

    Development of a method of electrodeposition of non-ferrous metals on a rotating cathode covered with gallium

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    Electrodeposition of copper and nickel from acidic solutions using a rotating cathode coated with liquid and solid gallium has been studied. Methods of nonferrous metals separation from the gallium coating of the cathode were determined. Electrodeposition on the liquid gallium coating was carried out at a temperature of 50 °C. Separation of metals from gallium was performed by alkaline treatment. On the solid gallium cathode coating, electrodeposition was performed at 25 °C. The metal precipitates were separated from the cathode after it was heated. When using cathode with hard gallium coating the reduction of electric power consumption for copper by 85 % and for nickel by 15 % was obtained

    Comparative genomic analyses of nickel, cobalt and vitamin B12 utilization

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    Background: Nickel (Ni) and cobalt (Co) are trace elements required for a variety of biological processes. Ni is directly coordinated by proteins, whereas Co is mainly used as a component of vitamin B12. Although a number of Ni and Co-dependent enzymes have been characterized, systematic evolutionary analyses of utilization of these metals are limited. Results: We carried out comparative genomic analyses to examine occurrence and evolutionary dynamics of the use of Ni and Co at the level of (i) transport systems, and (ii) metalloproteomes. Our data show that both metals are widely used in bacteria and archaea. Cbi/NikMNQO is the most common prokaryotic Ni/Co transporter, while Ni-dependent urease and Ni-Fe hydrogenase, and B12-dependent methionine synthase (MetH), ribonucleotide reductase and methylmalonyl-CoA mutase are the most widespread metalloproteins for Ni and Co, respectively. Occurrence of other metalloenzymes showed a mosaic distribution and a new B12-dependent protein family was predicted. Deltaproteobacteria and Methanosarcina generally have larger Ni- and Co-dependent proteomes. On the other hand, utilization of these two metals is limited in eukaryotes, and very few of these organisms utilize both of them. The Ni-utilizing eukaryotes are mostly fungi (except saccharomycotina) and plants, whereas most B12-utilizing organisms are animals. The NiCoT transporter family is the most widespread eukaryotic Ni transporter, and eukaryotic urease and MetH are the most common Ni- and B12-dependent enzymes, respectively. Finally, investigation of environmental and other conditions and identity of organisms that show dependence on Ni or Co revealed that host-associated organisms (particularly obligate intracellular parasites and endosymbionts) have a tendency for loss of Ni/Co utilization. Conclusion: Our data provide information on the evolutionary dynamics of Ni and Co utilization and highlight widespread use of these metals in the three domains of life, yet only a limited number of user proteins

    Comparative genomic analyses of nickel, cobalt and vitamin B12 utilization

    Get PDF
    Background: Nickel (Ni) and cobalt (Co) are trace elements required for a variety of biological processes. Ni is directly coordinated by proteins, whereas Co is mainly used as a component of vitamin B12. Although a number of Ni and Co-dependent enzymes have been characterized, systematic evolutionary analyses of utilization of these metals are limited. Results: We carried out comparative genomic analyses to examine occurrence and evolutionary dynamics of the use of Ni and Co at the level of (i) transport systems, and (ii) metalloproteomes. Our data show that both metals are widely used in bacteria and archaea. Cbi/NikMNQO is the most common prokaryotic Ni/Co transporter, while Ni-dependent urease and Ni-Fe hydrogenase, and B12-dependent methionine synthase (MetH), ribonucleotide reductase and methylmalonyl-CoA mutase are the most widespread metalloproteins for Ni and Co, respectively. Occurrence of other metalloenzymes showed a mosaic distribution and a new B12-dependent protein family was predicted. Deltaproteobacteria and Methanosarcina generally have larger Ni- and Co-dependent proteomes. On the other hand, utilization of these two metals is limited in eukaryotes, and very few of these organisms utilize both of them. The Ni-utilizing eukaryotes are mostly fungi (except saccharomycotina) and plants, whereas most B12-utilizing organisms are animals. The NiCoT transporter family is the most widespread eukaryotic Ni transporter, and eukaryotic urease and MetH are the most common Ni- and B12-dependent enzymes, respectively. Finally, investigation of environmental and other conditions and identity of organisms that show dependence on Ni or Co revealed that host-associated organisms (particularly obligate intracellular parasites and endosymbionts) have a tendency for loss of Ni/Co utilization. Conclusion: Our data provide information on the evolutionary dynamics of Ni and Co utilization and highlight widespread use of these metals in the three domains of life, yet only a limited number of user proteins
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