Operation of a continuous flow liquid helium magnetic microscopy cryostat as a closed cycle system.

We demonstrate successful operation of a continuous flow liquid helium magnetic cryostat (Oxford Instruments, Microstat MO) in closed cycle operation using a modular cryocooling system (ColdEdge Technologies, Stinger). For the system operation, we have developed a custom gas handling manifold and we show that despite the lower cooling power of the cryocooler with respect to the nominal cryostat cooling power requirements, the magnetic cryostat can be operated in a stable manner. We provide the design of the gas handling manifold and a detailed analysis of the system performance in terms of cooling times, magnetic field ramping rates, and vibrations at the sample. Base temperatures can be reached within 10 h while the superconducting magnet can be energized at a ramping rate of 0.5 T/min. Vibrations are measured interferometrically and show amplitudes with a root mean square on the order of 5 nm, permitting the use of the system for sensitive magnetic microscopy experiments.

Discriminating between Coherent and Incoherent Light with Planar Metamaterials.

Planar metamaterials represent a powerful paradigm of optical engineering, which enables one to control the flow of light across structured material interfaces in the absence of high-order diffraction modes. We report on a discovery that planar metamaterials of a certain type, formed by nanopatterned metal films, respond differently to spatially coherent and incoherent light, enabling robust speckle-free discrimination between different degrees of light coherence. The effect has no direct analogue in natural optical materials and may find applications in nanoscale metadevices enhancing imaging, vision, detection, communication, and metrology.

Relationship between tablet splitting and compliance, drug acquisition cost, and patient acceptance.

As managed care pharmacy continues to grow and medication costs increase, pharmacy managers are continually looking for ways to reengineer distributive services to provide the most cost-effective care. In an effort to save money, the San Diego Veterans Affairs Healthcare System (SDVAHS) and other health systems have implemented tablet-splitting programs targeted at high-cost and widely prescribed medications. Despite this growing practice, published research examining the effects on compliance rates, patient acceptance, and actual cost savings is lacking. A recent computer-assisted literature search revealed only one study of tablet splitting that addressed patient compliance and acceptance. In that study, patients taking lovastatin and using a tablet splitter were mailed a questionnaire to assess their impressions of tablet splitting. A majority of the patients found tablet splitters easy to use and reported that compliance was not hindered. However, compliance was subjectively evaluated through patients' responses to questions; actual tablet counts were not performed. Furthermore, actual cost savings (if any) were not determined.

Computer dosing program for the initiation of vancomycin therapy.

The predictive performance of a computer dosing program used for initiating vancomycin therapy was studied. Initial serum vancomycin concentrations in 31 adult patients receiving vancomycin were estimated by using a computer program (T.D.M.S.) incorporating a two-compartment open model. Sixty-two serum vancomycin concentrations at steady state (Css) were obtained before and after one-hour infusions and compared with estimated Css values. Bias and precision were evaluated by calculating median error (ME) and median absolute error (MAE), respectively. Population-based estimates of volume of distribution (V) and clearance (CL) were compared with those obtained by fitting each patient's data set by using Bayesian analysis (BA) and non-linear least-squares regression (NLLS). Median (mean +/- S.D.) bias and precision for peak Css were 7.7 (10.2 +/- 10.8) and 7.7 (10.6 +/- 10.5) mg/L, and for trough Css were 7.4 (7.7 +/- 7.6) and 7.4 (8.8 +/- 6.2) mg/L. The medians were significantly different from zero. Estimated median (mean +/- S.D.) V, CL, and half-life were 0.72 L/kg, 0.60 (0.67 +/- 0.21) mL/min/kg, and 11.59 (12.87 +/- 3.91) hours. Median (mean +/- S.D.) CL values determined by BA and NLLS were 0.86 (0.89 +/- 0.32) and 0.85 (0.92 +/- 0.34) mL/min/kg, respectively. Both CL values were significantly greater than the population-based estimate. However, median V values determined by BA and NLLS did not differ from the population-based estimate. A revised clearance model derived from Bayesian analysis of data for the first 21 patients was tested in the 10 other patients and appeared to improve the predictive performance of the a priori model.(ABSTRACT TRUNCATED AT 250 WORDS)

Norethisterone and gestational diabetes.

In a single practice during the 21 years 1971-1991, the incidence of gestational diabetes in pregnancies in which norethisterone was prescribed was 32.4% (22 of 69) in comparison with 7.1% in pregnancies in which the women did not take norethisterone (137 of 1,684) (p < 0.001). Gestational diabetes was no less severe (degree of hyperglycaemia, need for insulin therapy) when associated with norethisterone. However, follow-up revealed that gestational diabetes when associated with norethisterone had a lesser risk of emerging diabetes mellitus and impaired glucose tolerance. Masculinization of a female fetus occurred in 5 of 39 (12.8%) exposed to norethisterone; all were cases of clitoral hypertrophy not requiring surgical treatment. Norethisterone in these 69 pregnancies accounted for 33.3% (5 of 15) cases of clitoral hypertrophy diagnosed in 100,756 consecutive births.

Concentration guidelines for parenteral antibiotics in fluid-restricted patients.

A guideline for the preparation of peripherally administered antibiotics in fluid-restricted patients was developed. A maximum osmolality of 560 mOsmol/kg was selected since this corresponds to the theoretical osmolality of dextrose 5% in NaCl 0.9%, a solution commonly administered peripherally without significant incidence of phlebitis. Percentage concentrations corresponding to 560 mOsmol/kg of 26 intravenous antibiotics were calculated using sodium chloride equivalents. The antibiotics were reconstituted using sterile water, dextrose 5%, and NaCl 0.9% to provide an osmolality of 560 mOsmol/kg. The resulting solutions were measured for osmolality using a freezing-point depression osmometer. A total of 78 solutions were prepared and measured in triplicate. Of the 78 measured osmolalities, 67 (86 percent) were within 20 percent of the desired 560 mOsmol/kg. Only two osmolalities were more than 10 percent above the projected value. The percentage concentrations of 26 antibiotics in three solutions corresponding to 560 mOsmol/kg are presented. A method is also provided for tailoring concentrations to achieve desired osmolalities other than 560 mOsmol/kg.