An improved dual-frequency technique for the remote sensing of ocean currents and wave spectra

A two frequency microwave radar technique for the remote sensing of directional ocean wave spectra and surface currents is investigated. This technique is conceptually attractive because its operational physical principle involves a spatial electromagnetic scattering resonance with a single, but selectable, long gravity wave. Multiplexing of signals having different spacing of the two transmitted frequencies allows measurements of the entire long wave ocean spectrum to be carried out. A new scatterometer is developed and experimentally tested which is capable of making measurements having much larger signal/background values than previously possible. This instrument couples the resonance technique with coherent, frequency agility radar capabilities. This scatterometer is presently configured for supporting a program of surface current measurements

Passive Mode-Locking of Monolithic InGaAs/AlGaAs Double Quantum Well Lasers at 42GHz Repetition Rate

Pulse trains with a 42GHz repetition rate were generated by monolithic InGaAs/AlGaAs double quantum well lasers at a wavelength of 985 [angstroms]. The cavity was electrically divided into three regions, one providing gain and the other two providing saturable absorption. The optical modulation has a depth greater than 98% and full-width at half-maximum under 6ps, and bias conditions for sustained mode-locking are determined

The Linear Boltzmann Equation as the Low Density Limit of a Random Schrodinger Equation

We study the evolution of a quantum particle interacting with a random potential in the low density limit (Boltzmann-Grad). The phase space density of the quantum evolution defined through the Husimi function converges weakly to a linear Boltzmann equation with collision kernel given by the full quantum scattering cross section.Comment: 74 pages, 4 figures, (Final version -- typos corrected

Broadband Tuning (170nm) of InGaAs Quantum Well Lasers

The wavelength tuning properties of strained InGaAs quantum well lasers using an external grating for feedback is reported. Tunable laser oscillation has been observed over a range of 170 nm, between 840 and 1010 nm, under pulsed current excitation. The optimal conditions for broadband tunability for the InGaAs lasers are different from GaAs lasers, which is attributed to a difference in spectral gain curves. Together with an optimised GaAs quantum well laser the entire region between 740 and 1010 nm is spanned

Management of Hallucinations and Psychosis in Parkinson's Disease

This is the author's accepted manuscript, made available with permission of the publisher. The final published version is available from ScienceDirect: http://dx.doi.org/10.1016/j.amjopharm.2010.08.004 (See the Published Version link, above.)BACKGROUND: Hallucinations and psychosis are common in patients with Parkinson's disease (PD), with reported prevalences of up to 48% and 80%, respectively. However, few randomized, double-blind, placebo-controlled trials evaluating the treatment options have appeared in the literature. The studies that have been published were complicated by lack of agreement on the diagnosis of psychosis in PD, poor completion rates, mixed populations that included dementia, and other issues. Several reviews, guidelines, and consensus statements have sought to establish standards for treating these symptoms of PD. In 2006, the American Academy of Neurology (AAN) published a practice guideline (based on articles published up to 2004) for management of depression, psychosis, and dementia in patients with PD. Since then, a number of relevant studies have been published. OBJECTIVE: The purpose of this article was to review data that have appeared in the literature since publication of the AAN guideline regarding the management of hallucinations and psychosis in PD. METHODS: A literature search of the PubMed, CINAHL, and PsychInfo databases was conducted for human studies published in English from January 2004 to June 2010. All clinical studies were included except case reports and case series. Studies with <20 participants were also excluded. Search terms included psychosis, hallucinosis, hallucination, delusion, Parkinson, atypical antipsychotic, neuroleptic, aripiprazole, clozapine, olanzapine, quetiapine, risperidone, and ziprasidone. RESULTS: Thirteen studies were included in the review: 3 studies of clozapine, 7 studies of quetiapine, 2 head-to-head trials comparing quetiapine and clozapine, and 1 noncomparative trial of clozapine or quetiapine interventions. Most of the studies included participants with a mean age in the early to mid 70s and a mean duration of PD typically >10 years. CONCLUSIONS: Results of the identified studies suggested that patients with PD might benefit from long-term clozapine therapy. Results of the quetiapine studies were conflicting. However, no statistically significant difference in effectiveness was found between quetiapine and clozapine in comparative trials. The significance of the differences in treatment responses between patients with dementia and those without dementia remains unclear, and it was not possible to draw conclusions for or against other atypical antipsychotics because of insufficient evidence. Further studies are needed to address the methodologic issues in the current trials and to assess safety issues in larger cohorts

Foster impedance data modeling via singly terminated LC ladder networks

In this work, a lossless model is developed for the given Foster impedance data. In the model, a 2-port shortor open-terminated LC ladder is used. After applying the proposed algorithm, a realizable driving-point reactance function that fits the given data is obtained. Next, this function is synthesized, resulting in the desired model. In the algorithm, there is no need to select a circuit topology for the model. Two examples are given to illustrate the utilization of the proposed modeling algorithm

Parametric study of cavity length and mirror reflectivity in ultralow threshold quantum well InGaAs/AlGaAs lasers

Record low CW threshold currents of 16 μA at-room temperature and 21 μA at cryogenic temperature have been demonstrated in buried heterostructure strained layer, single quantum well InGaAs/AlGaAs lasers with a short cavity length and high reflectivity coatings

Very High Modulation Efficiency of Ultralow Threshold Current Single Quantum Well InGaAs Lasers

A record high current modulation efficiency of 5 GHz/[sqrt](mA) has been demonstrated in an ultralow threshold strained layer single quantum well InGaAs laser