Interacting non-BPS black holes

We explain how to exploit systematically the structure of nilpotent orbits to obtain a solvable system of equations describing extremal solutions of (super-)gravity theories, i.e. systems that can be solved in a linear way. We present the procedure in the case of the STU model, where we show that all extremal solutions with a flat three-dimensional base are fully described with the help of three different nilpotent orbits: the BPS, the almost-BPS and the composite non-BPS. The latter describes a new class of solutions for which the orientation of half of the constituent branes have been inverted with respect to the BPS one, such that all the centres are intrinsically non-BPS, and interact with each others. We finally recover explicitly the ensemble of the almost-BPS solutions in our formalism and present an explicit two-centre solution of the new class.Comment: 49 page

Prospective Evaluation of a Hospital Epidemiologist's Activities at a European Tertiary-Care Medical Center

Abstract Objective: Assessment of the distribution of tasks and consultations provided by the hospital epidemiologist (HE) at University Hospital of Zurich (UHZ). Design: Prospective collection of data on hospital epidemiology consultations over a 3-year period (1995-1997). Time spent per consultation and activities of infection control practitioners were not recorded. Setting: A 1,040-bed tertiary-care university hospital in Zurich, Switzerland. Results: Between January 1, 1995, and December 31, 1997, the HE received 1,660 requests for consultation. Advice or action was sought in the following areas: epidemiology (27.5% of requests); quality assurance, including antibiotic utilization and technology assessment (24.8%); infection control and practice guidelines (22.5%); disinfection and sterilization (11.6%); clinical infectious diseases (13.4%). During 1997, 35% of epidemiology consults were related to methicillin-resistant Staphylococcus aureus and 5.8% to tuberculosis. Public or private hospitals not affiliated with UHZ requested 40% of all consults. Conclusions: This study shows that HEs are involved in many different activities. Only 27.5% of hospital epidemiology consultations were directly related to issues of epidemiology. Practical knowledge of the methodologies for continuous quality improvement and assessment of various new technologies is important for HEs. The results of this study may be useful in discussions between HEs and administrators about allocation of resources or issues of reimbursemen

Epidemiology and Clinical Impact of Glycopeptide Resistance in Staphylococcus aureus

Abstract : Staphylococcus aureus with resistance to glycopeptide antibiotics has been considered to be a rare cause of clinically relevant infections. A review of the current literature shows that this is indeed the case for infections caused by S. aureus with high-level resistance to vancomycin (VRSA), as only isolated cases have been reported. VRSA develops following the insertion of the vanA gene, which is transferred from enterococci with vancomycin resistance. On the other hand, infections caused by S. aureus with intermediate resistance to glycopeptides (VISA), or heterogeneously expressed intermediate level glycopeptide resistance (hVISA), are more common. These infections are associated with clinical failure of glycopeptide therapy. While the biochemical and phenotypic features including a thickened cell wall of hVISA and VISA are well known, the genetic basis of these phenotypes remains unknown. Certain genetic regulatory elements such as agr II are associated with reduced susceptibility of S. aureus to glycopeptides. Available data suggest that certain infections might be successfully treated using higher doses of vancomycin. However, as treatment failure is particularly common in infections with a high bacterial load, it may be necessary to resort to other antibiotics such as linezolid, often combined with surgical intervention, in order to successfully treat these infections. Open questions regarding diagnosis, pathogenesis, epidemiology, and treatment of glycopeptide resistance in S. aureus are addressed in this review. Clinicians should be aware of these aspects, since S. aureus remains one of the most important bacteria in modern medicin