73 research outputs found

    Part I - Application of ultra-stable oscillators to one-way ranging systems. Part II - Fluctuation spectra of ultra- stable oscillators - Measurement and estimation Final report

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    Application of ultrastable oscillators to one-way ranging systems - Measurement technique for determining phase fluctuation spectrum of highly stable oscillator

    Optical altimeter receiver systems study and design for a spaceborne laser altimeter

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    Design and specifications for optical altimeter receiver system

    Retrodirective transponder feasibility experiment

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    Test program on feasibility of digital phase measuring subsystem of pulse-coherent retrodirective transponde

    Statistical Communication Theory

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    Contains reports on six research projects.National Institutes of Health (Grant MH-04737-02

    Improved results for N=(2,2) super Yang-Mills theory using supersymmetric discrete light-cone quantization

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    We consider the (1+1)-dimensional N=(2,2){\cal N}=(2,2) super Yang--Mills theory which is obtained by dimensionally reducing N=1{\cal N}=1 super Yang--Mills theory in four dimension to two dimensions. We do our calculations in the large-NcN_c approximation using Supersymmetric Discrete Light Cone Quantization. The objective is to calculate quantities that might be investigated by researchers using other numerical methods. We present a precision study of the low-mass spectrum and the stress-energy correlator . We find that the mass gap of this theory closes as the numerical resolution goes to infinity and that the correlator in the intermediate rr region behaves like rāˆ’4.75r^{-4.75}.Comment: 18 pages, 8 figure

    Airway stent complications: the role of follow-up bronchoscopy as a surveillance method.

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    Background: Airway stenting has become an integral part of the therapeutic endoscopic management of obstructive benign and malignant central airway diseases. Despite increased use of airway stents and frequent stent-associated complications, no clear guidelines for surveillance and maintenance exist. This study aim is to elucidate predictive factors associated with development of stent complications, as well as an optimal surveillance period for follow-up bronchoscopy for early detection and possible prevention of stent-associated complications. Methods: Retrospective cohort study of all patients who underwent airway stent placements at our institution from April 2010 to December 2013 for benign and malignant airway diseases. Metallic, silicone (straight, Y stent, T-tube) and hybrid stents were included in the study. Stent complications were analyzed at the time of follow-up bronchoscopy performed four to six weeks after initial stent placement or earlier if patients became symptomatic. Results: The study included 134 patients of which 147 stents were placed. Follow-up bronchoscopy was performed in 94 patients. Symptomatic status at the time of follow-up bronchoscopy was not associated with stent complications [odds ratio (OR) =1.88; 95% CI: 0.79-4.45; P=0.15]. Patient age, sex, indication for stent placement, and stent location, were not associated with development of complications (all P\u3e0.05). Compared to all other stents, hybrid stents were more likely to migrate (OR =6.60; 95% CI: 2.16-20.2; P=0.001) or obstruct by secretions (OR =2.53; 95% CI: 1.10-5.84; P=0.03). There were no complications associated with surveillance bronchoscopy. Conclusions: Surveillance bronchoscopy within 4 to 6 weeks of stent placement may be useful for early detection of complications and their subsequent management, regardless of symptomatic status and indication for stent placement. Prospective multicenter studies are needed to compare optimal surveillance methods and the impact on patient mortality, morbidity and healthcare costs
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