9,037 research outputs found
Parametric instabilities in magnetized multicomponent plasmas
This paper investigates the excitation of various natural modes in a
magnetized bi-ion or dusty plasma. The excitation is provided by parametrically
pumping the magnetic field. Here two ion-like species are allowed to be fully
mobile. This generalizes our previous work where the second heavy species was
taken to be stationary. Their collection of charge from the background neutral
plasma modifies the dispersion properties of the pump and excited waves. The
introduction of an extra mobile species adds extra modes to both these types of
waves. We firstly investigate the pump wave in detail, in the case where the
background magnetic field is perpendicular to the direction of propagation of
the pump wave. Then we derive the dispersion equation relating the pump to the
excited wave for modes propagating parallel to the background magnetic field.
It is found that there are a total of twelve resonant interactions allowed,
whose various growth rates are calculated and discussed.Comment: Published in May 2004; this is a late submission to the archive. 14
pages, 8 figure
Telerobotic workstation design aid
Telerobot systems are being developed to support a number of space mission applications. In low earth orbit, telerobots and teleoperated manipulators will be used in shuttle operations and space station construction/maintenance. Free flying telerobotic service vehicles will be used at low and geosynchronous orbital operations. Rovers and autonomous vehicles will be equipped with telerobotic devices in planetary exploration. In all of these systems, human operators will interact with the robot system at varied levels during the scheduled operations. The human operators may be in either orbital or ground-based control systems. To assure integrated system development and maximum utility across these systems, designers must be sensitive to the constraints and capabilities that the human brings to system operation and must be assisted in applying these human factors to system development. The simulation and analysis system is intended to serve the needs of system analysis/designers as an integrated workstation in support of telerobotic design
Suppression of allograft rejection with FK506: I. prolonged cardiac and liver survival in rats following short-course therapy
Heterotopic heart and orthotopic liver grafts from ACI donors were transplanted to Lewis rat recipients that were treated with a 3 (or 4) day course of FK506 IM that was started on postoperative day 0, 2, 3, 4, 5, or 6. Hearts, which rejected after a median of 6 days in untreated controls, always had prolonged survival (median 91 days) when treatment was started on postoperative day 4. The results were inferior when treatment was started earlier or later than this, but even when the first dose of FK506 was on postoperative day 5, one day before rejection was imminent in controls, the median survival was 50 days. The poorest results with a median graft survival of only 36 days were obtained when injections were on days 0–3. Results were similar with liver grafts that rejected after a median time of 10 days in nontreated controls but that usually survived permanently after a 3 (or 4) day FK506 course starting on day 0, 2, 3, or 4. Therapy started on day 6 was too late. © 1990 by Williams & Wilkins
Hamster-to-rat heart and liver xenotransplantation with FK506 plus antiproliferative drugs
Heterotopic hamster hearts transplanted to unmodified LEW rats underwent humoral rejection in 3 days. Survival was prolonged to a median of 4 days with 2 mg/kg/day FK506. As monotherapy, 15 mg/kg/day cyclophosphamide greatly prolonged graft survival-far more than could be accomplished with RS-61443, brequinar (BQR), mizoribine, methotrexate, or deoxyspergualin. However, when FK506 treatment, which was ineffective alone, was combined with a short induction course (14 or 30 days) of subtherapeutic BQR, RS-61443, or cyclophosphamide, routine survival of heart xenografts was possible for as long as the daily FK506 was continued. In addition, a single large dose of 80 mg/kg cyclophosphamide 10 days preoperatively allowed routine cardiac xenograft survival under FK506. The ability of these antimetabolites to unmask the therapeutic potential of FK506 correlated, although imperfectly, with the prevention of rises of preformed heterospecific cytotoxic antibodies immediately postoperatively. As an adjunct to FK506, azathioprine was of marginal value, whereas mizoribine, methotrexate, and deoxyspergualin (DSPG) were of intermediate efficacy. After orthotopic hepatic xenotransplantation, the perioperative survival of the liver with its well-known resistance to antibodies was less dependent than the heart on the antimetabolite component of the combined drug therapy, but the unsatisfactory results with monotherapy of FK506, BQR, RS-61443, or cyclophosphamide were changed to routine success by combining continuous FK506 with a short course of any of the other drugs. Thus, by breaking down the antibody barrier to xenotransplantation with these so-called antiproliferative drugs, it has been possible with FK506 to transplant heart and liver xenografts with consistent long-term survival of healthy recipients
P4‐026: Use of statins, LDL‐C and incidence of cognitive impairment or dementia in a seven‐year cohort study of older Mexican‐Americans
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152653/1/alzjjalz2008052090.pd
The german camera evaluation project - results from the geometry group
The so-called German camera evaluation project was initiated by the German society of Photogrammetry, Remote Sensing and Geoinformation (DGPF) in order to allow for comprehensive empirical test on photogrammetric digital airborne camera systems. During this test, the digital camera systems DMC, Ultracam-X, ADS40 (2nd generation), JAS-150, Quattro DigiCAM and AIC-x1 were flown in the test site Vaihingen/Enz in summer 2008. In addition, RMK analogue images and ALS50 LiDAR data were recorded for comparison, while reference measurements on the ground were made available as well. Parts of the test field were also covered from hyper-spectral sensor flights, namely the AISA+ and ROSIS system. After data collection all this material was prepared, documented and distributed to more than 30 institutions which participated in the evaluation and formed the project network of expertise. This evaluation phase included topics like the analysis of geometric accuracy and sensor calibration, the radiometric performance including on-site radiometric calibration and multi-spectral land classifications. Additionally, the performance of photogrammetric surface model generation and the potential of manual stereo plotting from digital images were investigated. Within this paper, the major findings from the geometric evaluations, namely sensor orientation and height model generation are presented
Оценка погрешности выделения сигнала из шума на основе синхронного детектирования
Объектом исследования является метод синхронного детектирования, его применение и оценка погрешностей при разных параметрах.
Цель работы – анализ составляющих погрешности при выделении сигнала методом синхронного детектирования.
В процессе исследования проводился анализ принципа синхронного детектирования, аналитический обзор средств измерений на основе синхронного детектирования. Также проводилась оценка составляющих погрешности при отклонении частот детектируемого и опорного сигнала, влияние некогерентности опорного сигнала, влияние не ортогональности опорных сигналов.
В результате исследования были получены оценки составляющих
погрешности при отклонении частот детектируемого и опорного сигнала, а также было выявлено влияние некогерентности опорного сигнала, влияние не ортогональности опорных сигналов. Экономическая эффективность/значимость работы: реализация данного научно-технического проекта, позволяет увеличить эффективность производства, с ресурсосберегающей стороны путем внедрения новых синхронных усилителей с меньшей погрешностью, это позволит производить измерения более точно.The object of the study is the method of synchronous detection, its application and estimation of errors in different parameters.
The work purpose – the analysis of the error components when the selection signal by the method of synchronous detection.
In the process of investigation the analysis of the principle of synchronous detection, analytical review of measurement tools based on synchronous detection. Also was evaluated the components of the error in the frequency deviation detected and the reference signal, the influence of the incoherence of the reference signal, the influence of orthogonality of a reference signal.
The study produced estimates of the components of
error in the frequency deviation detected and the reference signal, but also revealed the effects of incoherence of the reference signal, the influence of orthogonality of a reference signal. Economic efficiency and significance of the work: the implementation of this research project, allows to increase production efficiency, resource-saving hand through the introduction of new synchronous amplifiers with reduced error, this will allow to measure more precisely
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