Verification of CPT-invariance of QED bound states for the production of muonium or antimuonium in scattering of electrons or positrons by nuclei

A possibility of a verification of CPT-invariance of QED for bound states by example of muonium or antimuonium produced in reactions of scattering of electrons or positrons by nuclei is considered. The number of events of the muonium production is estimated for contemporary accelerators. The method of the detection of muonium by measuring of oscillations of the decay curve caused by the interference between the ground and excited state of muonium is suggested. The admixture of the excited muonium to the final state is calculated.Comment: 7 pages, 3 figures, Latex, published in JETP 74, 196 (2001), corrected mistypes in eqs. (2.2), (2.4), (2.7

Continuous selections of multivalued mappings

This survey covers in our opinion the most important results in the theory of continuous selections of multivalued mappings (approximately) from 2002 through 2012. It extends and continues our previous such survey which appeared in Recent Progress in General Topology, II, which was published in 2002. In comparison, our present survey considers more restricted and specific areas of mathematics. Note that we do not consider the theory of selectors (i.e. continuous choices of elements from subsets of topological spaces) since this topics is covered by another survey in this volume

Microfabrication and characterization of a silicon-based millimeter scale, PEM fuel cell operating with hydrogen, methanol, or formic acid

A silicon-based microfabricated fuel cell has been developed to provide a high energy and power density power source on the millimeter size scale. An integrated silicon microscale membrane electrode assembly (Si-μMEA) consisting of a Nafion 112™ membrane bonded between two electrodes on microstructured silicon substrates forms the core element of this polymer electrolyte membrane fuel cell. The use of silicon meshes that serve the purpose of catalyst support, current collector, and structural element provides a promising alternative to the traditional gas diffusion layer-based MEAs for the development of robust, high-performance microfuel cells. The cell performance was characterized using hydrogen, methanol, and concentrated formic acid–water fuels at the anode, and oxygen at the cathode. The catalyst used for each fuel was Pt black. Preliminary results show that the microfabricated fuel cell running on formic acid may be a promising alternative for fuel cell applications running at ambient temperature and pressure, provided additional work on catalyst improvement, assembly, and packaging is performed so that the power density achieves that of traditional forced fed PEM fuel cell design. © 2004 Elsevier B.V. All rights reserved