Note: Efficient diode laser line narrowing using dual, feed-forward + feed-back laser frequency control.

We have achieved distributed feedback laser diode line narrowing by simultaneously acting on the diode current via a feed-back loop and on an external electrooptic phase modulator in feed-forward actuator. This configuration turns out to be very efficient in reaching large bandwidth in the phase correction: up to 15 MHz with commercial laser control units. About 98% of the laser power undergoes narrowing. The full width at half maximum of the narrowed optical spectrum is of less than 4 kHz. This configuration appears to be very convenient as the delay in the feed-forward control electronics is easily compensated for by a 20 m optical fiber roll.

Desynchronization: a novel model to induce heart failure.

BACKGROUND: Previous large animal heart failure models led to inhomogeneous results. Therefore, we developed a novel model combining rapid pacing with forced ventricular desynchronization. METHODS: Heart failure was induced in 20 pigs during a pacing period of 21 days. Group A (n = 10) received one right ventricular lead (220 bpm). In group B (n = 10), two leads were implanted in different right ventricular regions with beat-to-beat alternation of activation sites (each lead 110 bpm). Sham-operated pigs (n = 6) served as controls. Hemodynamics were invasively evaluated and tissue was analyzed by immunohistochemistry and zymography. RESULTS: Hemodynamics were significantly more impaired in group B with an increase of pulmonary capillary wedge and central venous pressure and a reduction of cardiac index (control 4.3 +/- 0.1 l/min/m (2); A 3.6 +/- 0.2; B 2.9 +/- 0.2, P < 0.05). Heart-to-body weight ratio was significantly higher in group B. Histological analyses showed a significant increase of cell diameters and interstitial fibrosis with significantly higher collagen contents in group B. CONCLUSION: The new model with a combination of rapid pacing and forced desynchronization of the ventricular contraction is superior to traditional heart failure models induced solely by rapid pacing.

New manifestation of atomic parity violation in cesium: a chiral optical gain induced by linearly polarized 6S-7S excitation.

We have detected, by using stimulated emission, an atomic parity violation (APV) in the form of a chiral optical gain of a cesium vapor on the 7S-6P(3/2) transition, consecutive to linearly polarized 6S-7S excitation. We demonstrate the validity of this detection method of APV, by presenting a 9% accurate measurement of expected sign and magnitude. We stress several advantages of this new approach which fully exploits the cylindrical symmetry of the setup. Future measurements at the percent level will provide an important cross-check of an existing more precise result obtained by a different method.

Psychological predictors of sexual behaviors related to AIDS transmission.

This study was designed to assess the differential value of several psychological variables with regard to predicting safe-sex behavior. A sample of 94 male and 179 female undergraduate students, ranging in age from 16 to 66 years, were surveyed about sexual issues related to safe-sex practices. The survey included scales measuring participants' knowledge of transmission of AIDS, self-perception of safe-sex communication, fear and concern about AIDS, attitudes toward AIDS victims, and self-report of risky behavior. Several interesting relationships among predictor variables were found. For instance, favorable attitudes toward AIDS victims were positively correlated with knowledge about AIDS transmission, perceived communication with partners about safe sex, and fear of acquiring AIDS. However, only two predictor variables were independently predictive of self-reports of risky sexual behavior; specifically, fear about AIDS transmission was positively correlated with risky behavior, while communication was negatively correlated with risky behavior. These data suggest a need for a model that allows for complex, reciprocal relationships between the cognitive, emotional, and behavioral components of safe-sex practice. Implications are applied to research with college populations.

Implementing a continuous renal replacement therapies program.

Initiating and maintaining a continuous renal replacement therapy (CRRT) program presented more challenges than first anticipated; however, problems remained within the health care team's ability to solve. Here a multidisciplinary group reflects on what was done, should have been done, and remains to be done to offer effective CRRT at this university medical center. All participating members have come to realize that communication and collaboration are necessary to accomplish implementation of a complex program such as CRRT.