What is a Quantum Shock Wave?

Shock waves are examples of the far-from-equilibrium behavior of matter; they are ubiquitous in nature, yet the underlying microscopic mechanisms behind their formation are not well understood. Here, we study the dynamics of dispersive quantum shock waves in a one-dimensional Bose gas, and show that the oscillatory train forming from a local density bump expanding into a uniform background is a result of quantum mechanical self-interference. The amplitude of oscillations, i.e., the interference contrast, decreases with the increase of both the temperature of the gas and the interaction strength due to the reduced phase coherence length. Furthermore, we show that vacuum and thermal fluctuations can significantly wash out the interference contrast, seen in the mean-field approaches, due to shot-to-shot fluctuations in the position of interference fringes around the mean.

Laryngoscope handles: a potential for infection.

Laryngoscope handles do not usually come in direct contact with the patient's mucous membranes. Consequently, routine disinfection of laryngoscope handles is not currently standard practice unless gross contamination is clearly evident. Recent reports indicate that apparently clean handles may be contaminated with blood or body fluids. No report examined microbes on handles. The present article describes the incidence and types of microbes on laryngoscope handles after their use in the operating rooms of a 502-bed medical center in northwestern Pennsylvania. Twenty laryngoscope handles were cultured on Mueller Hinton 5% sheep blood agar plates. The plates were incubated at 37 degrees C for 48 hours and examined for growth. The identification, incidence, and susceptibility patterns of organisms were determined. Microorganisms were present on all 20 laryngoscope handles. Nine different types were isolated; some strains were resistant to multiple antibiotics. Organisms were categorized as contaminants or opportunistic pathogens. The presence of opportunistic pathogens places anesthesia providers and patients at risk of nosocomial infections. Based on the recommendations of the 1997 American Association of Nurse Anesthetists' Infection Control Guide and the results of the present study, institutional guidelines should be established for the use of disposable laryngoscope covers, high-level (destroying all microorganisms with the exception of high numbers of bacterial spores) disinfection, or sterilization of laryngoscope equipment between each patient use.

Marketing Medicaid drugs: an analysis of cost factors.

The cost of drugs dispensed through the Medicaid program is the focus of this article. The research question addressed is, "What variables raise or lower the expense of marketing drugs to Medicaid recipients?" Medicaid drug programs are dichotomized into high- and low-cost groups and variables are identified that are linked with either the more or less expensive programs. Three groups should be interested in identifying factors that increase or decrease the cost of marketing drugs to Medicaid patients--pharmacy managers, Medicaid administrators at the state and federal levels, and public aid recipients.

Cost-benefit analysis of prospective pharmacokinetic dosing of nortriptyline in depressed inpatients.

A retrospective chart review was conducted on depressed inpatients to determine the economic impact of prospective pharmacokinetic dosing vs. empirical dosing of tricyclic antidepressants. The benefit/cost ratio of 2.5 indicated that the benefits of prospective dosing more than doubled the cost. The prospectively dose patients were discharged significantly earlier, i.e. 6.1 days than the empirically dosed patients and they also returned to work significantly earlier, i.e. 55.4 days than the control group.

Interpretation of research data: other multivariate methods.

Four techniques of multivariate data analysis are described: discriminant analysis, factor analysis, cluster analysis, and multidimensional scaling. Objectives and applications, data requirements, mechanism of operation, methods of evaluation, and advantages and disadvantages of each method are covered. Multivariate methods are not substitutes for the researcher's use of proper study design. Investigators should try to avoid using a favorite or familiar technique across all research situations.