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151.
DD Lund FM Faraci H Ooboshi BL Davidson DD Heistad 《Canadian Metallurgical Quarterly》1999,30(1):120-125
OBJECTIVE: Regional presynaptic dopaminergic function and its regulation by dopamine agonists in different stages of PD can be measured by L-[11C]dopa and PET. In the current investigation, we studied the effects of therapeutic apomorphine on L-[11C]dopa uptake in patients with early and advanced PD. BACKGROUND: With disease progression and chronic dopamine agonist treatment, motor response complications supervene in a majority of PD patients. It is assumed that both presynaptic and postsynaptic changes in the dopaminergic system act to modify dopaminergic efficacy. METHODS: Patients with early and advanced stages of PD were included in the study. All patients were investigated twice with PET and L-[11C]dopa drug free and during a subsequent standardized therapeutic apomorphine infusion. RESULTS: Subregional analysis of the striatum showed differences in the effects of apomorphine infusion on the L-[11C]dopa influx rate in the two patient categories. In patients with early and uncomplicated PD, apomorphine infusion decreased the L-[11C]dopa influx rate. This decrease was most pronounced in the dorsal part of the putamen. In advanced PD patients, apomorphine did not affect the striatal L-[11C]dopa influx rate. CONCLUSIONS: We suggest that in mild and stable PD an upregulated presynaptic inhibitory feedback regulation, particularly in the dorsal putamen, acts to maintain congruity within the dopaminergic system in response to antiparkinsonian medication. However, this inhibitory feedback regulation is diminished with the progression of nigrostriatal degeneration and chronic dopamine agonist treatment. 相似文献
152.
Wood Joanne V.; Heimpel Sara A.; Newby-Clark Ian R.; Ross Michael 《Canadian Metallurgical Quarterly》2006,90(6):ii
Reports an error in "Snatching Defeat From the Jaws of Victory: Self-Esteem Differences in the Experience and Anticipation of Success" by Joanne V. Wood, Sara A. Heimpel, Ian R. Newby-Clark and Michael Ross (Journal of Personality and Social Psychology, 2005[Nov], Vol 89[5], 764-780). There are typographical errors in Table 2 (certain values should not have been in bold face). The corrected table is provided in the erratum. (The following abstract of the original article appeared in record 2005-15658-009.) Successes--defined broadly as meeting important standards or receiving positive evaluations--are widely assumed to be enjoyed equally by people with high self-esteem (HSEs) and low self-esteem (LSEs). Three studies examined the contradictory hypothesis that HSEs react more favorably to success than do LSEs and that success brings about certain unfavorable consequences for LSEs. Undergraduate participants reacted to a laboratory-manipulated success (Studies 1 and 2) or imagined highly positive events in the future (Study 3). Self-esteem differences emerged in anxiety, thoughts about the self, and (in Study 3) thoughts about non-self-related aspects of the event. LSEs were more anxious than HSEs after succeeding, success improved HSEs' self-relevant thoughts but not LSEs', and LSEs focused more on success's negative aspects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
153.
It has been proposed that the current design of in-vehicle displays may not be appropriate for the older driver. This paper describes an empirical, road-based investigation of the benefits to older and younger drivers of providing landmarks within the instructions presented by an in-vehicle navigation system. Thirty two participants navigated a challenging urban route using either landmarks or distance information to identify the location of forthcoming manoeuvres. A range of driver behaviour measures were collected, including visual glance data, driving errors, driver workload, navigation errors, navigation confidence, and pre and post-trial driver attitudinal responses. Results show that, for older and younger drivers, landmarks reduced the time spent glancing to a visual display, reduced navigation and driving errors, and influenced driver confidence. There were some key differences between the older and younger drivers. The wider implications for the design of in-car interfaces for the older driver are discussed. 相似文献
154.
155.
Felix Hartanto Jussi Kangasharju Martin Reisslein Keith Ross 《Multimedia Tools and Applications》2006,31(2):221-245
Because Internet access rates are highly heterogeneous, many video content providers today make available different versions of the videos, with each version encoded at a different rate. Multiple video versions, however, require more server storage and may also dramatically impact cache performance in a traditional cache or in a CDN server. An alternative to versions is layered encoding, which can also provide multiple quality levels. Layered encoding requires less server storage capacity and may be more suitable for caching; but it typically increases transmission bandwidth due to encoding overhead. In this paper we compare video streaming of multiple versions with that of multiple layers in a caching environment. We examine caching and distribution strategies that use both versions and layers. We consider two cases: the request distribution for the videos is known a priori; and adaptive caching, for which the request distribution is unknown. Our analytical and simulation results indicate that mixed distribution/caching strategies provide the best overall performance.A shorter version of this work has appeared in Proc. of IEEE International Conference on Multimedia and Expo (ICME), Vol. 2, pages 45–48, Lausanne, Switzerland, August 2002 相似文献
156.
Visually impaired users require web page interfaces that they can interact with. Providing such interfaces is necessary to serve this community, and is required by government regulation. This paper describes the unique web access requirements of visually impaired users. It reviews surveys of the suitability of web sites for the partially sighted and blind. Most web sites do not meet the requirements of the UK and other governments. In addition, serving the visually impaired is a marketing opportunity for organizations, as there is an ever increasing population with potential sight problems. 相似文献
157.
Augmented geophysical data interpretation through automated velocity picking in semblance velocity images 总被引:1,自引:0,他引:1
J. Ross Beveridge Charlie Ross Darrell Whitley Barry Fish 《Machine Vision and Applications》2002,13(3):141-148
Velocity picking is the problem of picking velocity–time pairs based on a coherence metric between multiple seismic signals.
Coherence as a function of velocity and time can be expressed as a 2D color semblance velocity image. Currently, humans pick
velocities by looking at the semblance velocity image; this process can take days or even weeks to complete for a seismic
survey. The problem can be posed as a geometric feature-matching problem. A feature extraction algorithm can recognize islands
(peaks) of maximum semblance in the semblance velocity image: a heuristic combinatorial matching process can then be used
to find a subset of peaks that maximizes the coherence metric. The peaks define a polyline through the image, and coherence
is measured in terms of the summed velocity under the polyline and the smoothness of the polyline. Our best algorithm includes
a constraint favoring solutions near the median solution for the local area under consideration. First, each image is processed
independently. Then, a second pass of optimization includes proximity to the median as an additional optimization criterion.
Our results are similar to those produced by human experts.
Accepted: 15 June 2001 相似文献
158.
D.L. Ross D.M. Osborne J.H. George 《Structural and Multidisciplinary Optimization》2002,23(6):460-466
While a considerable body of research has investigated the dual response problem, there is a need to reflect decision maker preferences in the simultaneous optimization of the response functions. In this paper, we present a mathematically rigorous approach for incorporating decision maker preferences. By interpreting the Lagrangian as a value function and the Lagrange multiplier as a preference ratio, candidate solutions are explored that reflect decision maker preferences. We consider the dual response approach to the simultaneous maximization of two responses modelled as quadratic forms. A function relating the responses and the value of the Lagrange multiplier is derived, and appropriate restrictions for the multiplier are discussed. We present the approach in algorithmic form and provide an example that demonstrates the application of the method. 相似文献
159.
It can be difficult for new faculty to get the information they need on issues such as teaching, advising, and setting up a research program. While some have excellent mentors, others have come to rely on trial and error or word of mouth. In 1996, the NSF Engineering Education Scholars Workshop began at Carnegie Mellon University to address the needs of new and future engineering faculty by:
- ? providing professional teaching development;
- ? offering guidance in supervising graduate students and conducting research;
- ? discussing likely engineering education and research challenges in the 21st century; and
- ? providing intellectual and social support with colleagues.
160.
In the last decade of the 20th century, we have witnessed a resurgence of interest in fuel cell technology, a technology whose basic principles were demonstrated in the mid-19th century. One of the drivers of this resurgence is the use of hydrogen as a transportation fuel, and the certification by the California Air Resources Board (CARB) of a hydrogen - air fuel cell powered vehicle as a "zero emission vehicle" or ZEV. Another driver is the simplicity of construction and assembly of fuel cell stacks when a polymer membrane is used as the electrolyte versus the more conventional aqueous electrolyte. The polymer electrolyte membrane (PEM) fuel cell offers the promise of substantially lower cost for the cell hardware. Unfortunately, two of the fundamental catalytic limitations that have plagued fuel cells for more than a century still remain: 1.) it is difficult to use any fuel other than highly purified hydrogen; 2.) there has been no cost-effective replacement of Pt as the electrocatalyst. Fortunately, there are signs that help is on the way, particularly with respect to the development of new electrocatalysts for electrooxidation of impure hydrogen, e.g. CO-contaminated, or even syngas. In this article, we describe some of these developments, which have come from over two decades of basic research on electrocatalysis. 相似文献