Semi-fermionic representation for spin systems under equilibrium and non-equilibrium conditions

We present a general derivation of semi-fermionic representation for spin operators in terms of a bilinear combination of fermions in real and imaginary time formalisms. The constraint on fermionic occupation numbers is fulfilled by means of imaginary Lagrange multipliers resulting in special shape of quasiparticle distribution functions. We show how Schwinger-Keldysh technique for spin operators is constructed with the help of semi-fermions. We demonstrate how the idea of semi-fermionic representation might be extended to the groups possessing dynamic symmetries (e.g. singlet/triplet transitions in quantum dots). We illustrate the application of semi-fermionic representations for various problems of strongly correlated and mesoscopic physics.Comment: Review article, 40 pages, 11 figure

Antimicrobial Activity and Spectrum of Cefovecin, a New Extended- Spectrum Cephalosporin, against Pathogens Collected from Dogs and Cats in Europe and North America

Cefovecin is a new extended-spectrum semisynthetic cephalosporin indicated for the treatment of bacterial infections in dogs and cats. This study evaluated the in vitro activity and spectrum of cefovecin against 2,641 recent clinical isolates (1,660 canine and 981 feline isolates) from Europe and the United States. MIC determinations against cefovecin and other reference antimicrobials were performed by broth microdilution methods recommended by the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS). Cefovecin demonstrated bactericidal activity against both gram-positive and gram-negative pathogens. Cefovecin exhibited in vitro activity against all major aerobic and anaerobic bacterial pathogens associated with skin, urinary tract, and periodontal infections in dogs and cats. The MIC(90) values of cefovecin against Staphylococcus intermedius, Escherichia coli, and Pasteurella multocida were 0.25 μg/ml, 1.0 μg/ml, and 0.06 μg/ml, respectively. No significant differences were observed in terms of the activities of cefovecin against pathogens from different European countries and against pathogens of European and U.S. origin

ZIRCONIUM PHOSPHONATES LAYERED STRUCTURE CATALYSTS WITH ORGANIC-ACID PENDANTS .1. PREPARATION AND PHYSICAL-PROPERTIES

Zirconium phosphonates layered structure (ZPLS) materials with various organic pendant groups have been synthesized. Their physical properties were investigated by means of SEM, BET, XRD, TGA/DTA and FT-IR. These properties, crystallinity in particular, depended strongly on preparation conditions and the nature of the pendant. In general, samples with a sulfonic acid pendant were not as crystalline as the carboxylic acid analogs. Crystalline samples exhibited a plate-like morphology as commonly observed for layered structure materials. Interlayer spacing of these materials was roughly proportional to the size of the pendant. In comparison with a conventional cation exchanged resin (Amberlyst 15), the layered structures with a sulfonic acid pendant showed similar IR characteristics, but much better thermal stabilityclose0