Familial interruption of the aortic arch

Diazepam is known to decrease organophosphate nerve agent-induced convulsions, neuropathology, and lethality in rhesus monkeys. We report that, when added to the previously fielded treatment regimen (pyridostigmine, atropine, and pralidoxime chloride), diazepam significantly protects the performance of rhesus monkeys trained in an equilibrium task, the Primate Equilibrium Platform (PEP), against deficits induced by the nerve-agent soman. If administered soon enough to minimize the occurrence of convulsions, diazepam should increase the probability of mission accomplishment and eventual complete recovery from nerve agent poisoning. Diazepam was fielded by the United States military services during Operations Desert Shield and Storm for the treatment of possible organophosphate toxicity.     

Integration of temporal and ordinal information during serial interception sequence learning.

The expression of expert motor skills typically involves learning to perform a precisely timed sequence of movements. Research examining incidental sequence learning has relied on a perceptually cued task that gives participants exposure to repeating motor sequences but does not require timing of responses for accuracy. In the 1st experiment, a novel perceptual-motor sequence learning task was used, and learning a precisely timed cued sequence of motor actions was shown to occur without explicit instruction. Participants learned a repeating sequence through practice and showed sequence-specific knowledge via a performance decrement when switched to an unfamiliar sequence. In the 2nd experiment, the integration of representation of action order and timing sequence knowledge was examined. When either action order or timing sequence information was selectively disrupted, performance was reduced to levels similar to completely novel sequences. Unlike prior sequence-learning research that has found timing information to be secondary to learning action sequences, when the task demands require accurate action and timing information, an integrated representation of these types of information is acquired. These results provide the first evidence for incidental learning of fully integrated action and timing sequence information in the absence of an independent representation of action order and suggest that this integrative mechanism may play a material role in the acquisition of complex motor skills. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Continuous-wave terahertz system with electro-optical terahertz phase control

A method of electro-optical control of the terahertz (THz) phase in continuous-wave photomixing THz systems is suggested and demonstrated. The method enables phase-sensitive detection without any moving mechanical components in the system. Additionally, the method allows lock-in detection without a mechanical chopper, which increases the signal-to-noise ratio of the system.     

Picosecond pulse generation in a GaAs/GaAlAs single-quantum-welllaser at the first and second subband transition

Picosecond optical pulses are generated in a single-quantum-well laser at the n=2 or n=1 quantized transition by tuning the optical gain spectra via the intracavity losses. The results for the generated pulses are discussed with respect to the influence of differential gain (dg/dN) and nonlinear gain saturation (∈) effects     

Effect of local medical opinion leaders on quality of care for acute myocardial infarction: a randomized controlled trial

CONTEXT: The effectiveness of recruiting local medical opinion leaders to improve quality of care is poorly understood. OBJECTIVE: To evaluate a guideline-implementation intervention of clinician education by local opinion leaders and performance feedback to (1) increase use of lifesaving drugs (aspirin and thrombolytics in eligible elderly patients, beta-blockers in all eligible patients) for acute myocardial infarction (AMI), and (2) decrease use of a potentially harmful therapy (prophylactic lidocaine). DESIGN: Randomized controlled trial with hospital as the unit of randomization, intervention, and analysis. SETTING: Thirty-seven community hospitals in Minnesota. PATIENTS: All patients with AMI admitted to study hospitals over 10 months before (1992-1993, N=2409) or after (1995-1996, N=2938) the intervention. INTERVENTION: Using a validated survey, we identified opinion leaders at 20 experimental hospitals who influenced peers through small and large group discussions, informal consultations, and revisions of protocols and clinical pathways. They focused on (1) evidence (drug efficacy), (2) comparative performance, and (3) barriers to change. Control hospitals received mailed performance feedback. MAIN OUTCOME MEASURES: Hospital-specific changes before and after the intervention in the proportion of eligible patients receiving each study drug. RESULTS: Among experimental hospitals, the median change in the proportion of eligible elderly patients receiving aspirin was +0.13 (17% increase from 0.77 at baseline), compared with a change of -0.03 at control hospitals (P=.04). For beta-blockers, the respective changes were +0.31 (63% increase from 0.49 at baseline) vs +0.18 (30% increase from baseline) for controls (P=.02). Lidocaine use declined by about 50% in both groups. The intervention did not increase thrombolysis in the elderly (from 0.73 at baseline), but nearly two thirds of eligible nonrecipients were older than 85 years, had severe comorbidities, or presented after at least 6 hours. CONCLUSIONS: Working with opinion leaders and providing performance feedback can accelerate adoption of some beneficial AMI therapies (eg, aspirin, beta-blockers). Secular changes in knowledge and hospital protocols may extinguish outdated practices (eg, prophylactic lidocaine). However, it is more difficult to increase use of effective but riskier treatments (eg, thrombolysis) for frail elderly patients.     

Nonlinear dynamics of semiconductor laser emission under variablefeedback conditions

A study was made of the behavior of external cavity semiconductor lasers with tilted external cavity mirrors providing variable feedback. The appearance of intermittent breakdowns of the light intensity induced by the tilting of the external mirror is demonstrated. The rate of the breakdowns of the light intensity is directly related to the relaxation oscillation frequency of the external cavity semiconductor laser. The authors describe the experimental observations theoretically by the coupled rate equations for the electric field density and the carrier density     

Picosecond gain dynamics of an actively mode-locked external-cavitylaser diode

We report a new experimental approach to study the temporal gain dynamics of an actively mode-locked external-cavity laser diode. The experiment can be viewed as an electrical pump-optical probe technique. Picosecond time resolution is achieved by synchronizing the actively mode-locked semiconductor laser to a mode-locked Ti:sapphire laser. The transmission of the Ti:sapphire pulses through the active region of the laser diode is then measured as a function of photon energy and delay time. Our experiment allows to investigate the dynamics of the entire gain spectrum with picosecond time resolution since the Ti:sapphire laser is wavelength tunable. On the basis of these data we are able to determine directly the wavelength dependence of the differential gain. The results compare well with microscopic calculations. The implication for the mode-locking behavior of the diode laser is discussed     

AlGaInAs/InP 1.5 μm MQW DFB laser diodes exceeding 20 GHzbandwidth

Buried mushroom multiquantum well DFB laser diodes with compressively strained GaInAs quantum wells and asymmetric confinement layer design are fabricated with a combined MBE/MOCVD technology. Packaged devices exhibit high -3 dB IM bandwidths for very low bias levels and a record bandwidth for this material system of 21 GHz     

High spectral tuning range of a modelocked InGaAs/InGaAsP MQW laserdiode due to light hole gain contribution

We report on modelocking of an external cavity multi quantum well semiconductor laser with an extremely wide spectral tuning range. Pulse widths in the order of 30 ps were obtained spectrally tunable from 1448 to 1563 nm. The broadening of the gain spectrum is experimentally shown to be due to the additional contribution of the electron n=1 to the light hole n=1 transition. This conclusion is supported by numerical calculations