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171.
The effects of a combination of the alpha2-adrenergic receptor antagonist (+/-)-idazoxan with L-DOPA methyl ester were examined in three of four female adult monkeys (Macaca nemestrina) rendered hemiparkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). (+/-)-Idazoxan (0.16, 0.63, and 1.0 mg/kg) was given i.m. 10 min before L-DOPA methyl ester (12.5 mg/kg). (+/-)-Idazoxan reduced the maximum peak of contralateral circling elicited during the first hour following injection of L-DOPA methyl ester, but prolonged the duration of the circling response up to 50% (p < 0.05). The data support a role for alpha2-adrenergic receptor mechanisms in modulating the effects of L-DOPA on nigrostriatal dopamine function in the MPTP monkey model of hemiparkinsonism. 相似文献
172.
Lunn KE Paulsen KD Roberts DW Kennedy FE Hartov A West JD 《IEEE transactions on medical imaging》2003,22(11):1358-1368
Brain shift during open cranial surgery presents a challenge for maintaining registration with image-guidance systems. Ultrasound (US) is a convenient intraoperative imaging modality that may be a useful tool in detecting tissue shift and updating preoperative images based on intraoperative measurements of brain deformation. We have quantitatively evaluated the ability of spatially tracked freehand US to detect displacement of implanted markers in a series of three in vivo porcine experiments, where both US and computed tomography (CT) image acquisitions were obtained before and after deforming the brain. Marker displacements ranged from 0.5 to 8.5 mm. Comparisons between CT and US measurements showed a mean target localization error of 1.5 mm, and a mean vector error for displacement of 1.1 mm. Mean error in the magnitude of displacement was 0.6 mm. For one of the animals studied, the US data was used in conjunction with a biomechanical model to nonrigidly re-register a baseline CT to the deformed brain. The mean error between the actual and deformed CT's was found to be on average 1.2 and 1.9 mm at the marker locations depending on the extent of the deformation induced. These findings indicate the potential accuracy in coregistered freehand US displacement tracking in brain tissue and suggest that the resulting information can be used to drive a modeling re-registration strategy to comparable levels of agreement. 相似文献
173.
Francis Jeffry Pelletier 《Journal of Logic, Language and Information》2001,10(1):87-114
In this essay I will consider two theses that are associated with Frege,and will investigate the extent to which Frege really believed them.Much of what I have to say will come as no surprise to scholars of thehistorical Frege. But Frege is not only a historical figure; he alsooccupies a site on the philosophical landscape that has allowed hisdoctrines to seep into the subconscious water table. And scholars in a widevariety of different scholarly establishments then sip from thesedoctrines. I believe that some Frege-interested philosophers at various ofthese establishments might find my conclusions surprising.Some of these philosophical establishments have arisen from an educationalmilieu in which Frege is associated with some specific doctrine at theexpense of not even being aware of other milieux where other specificdoctrines are given sole prominence. The two theses which I will discussillustrate this point. Each of them is called Frege's Principle, but byphilosophers from different milieux. By calling them milieux I do not want to convey the idea that they are each located at some specificsocio-politico-geographico-temporal location. Rather, it is a matter oftheir each being located at different places on the intellectuallandscape. For this reason one might (and I sometimes will) call them(interpretative) traditions. 相似文献
174.
Philippe Baptiste Peter Brucker Marek Chrobak Christoph Dürr Svetlana A. Kravchenko Francis Sourd 《Journal of Scheduling》2007,10(2):139-146
We study the problem of preemptive scheduling of n} jobs with given release times on m identical parallel machines. The objective is to minimize the average flow time. In this paper, show that when all jobs have
equal processing times then the problem can be solved in polynomial time using linear programming. Our algorithm can also
be applied to the open-shop problem with release times and unit processing times. For the general case (when processing times
are arbitrary), we show that the problem is unary NP-hard.
P. Baptiste and C. Dürr: Supported by the NSF/CNRS grant 17171 and ANR/Alpage.
P. Brucker: Supported by INTAS Project 00-217 and by DAAD PROCOPE Project D/0427360.
M. Chrobak: Supported by NSF grants CCR-0208856 and INT-0340752.
S. A. Kravchenko: Supported by the Alexander von Humboldt Foundation. 相似文献
175.
Information on subcategorization and selectional restrictions in a valency dictionary is important for natural language processing
tasks such as monolingual parsing, accurate rule-based machine translation and automatic summarization. In this paper we present
an efficient method of assigning valency information and selectional restrictions to entries in a bilingual dictionary, based
on information in an existing valency dictionary. The method is based on two assumptions: words with similar meaning have
similar subcategorization frames and selectional restrictions; and words with the same translations have similar meanings.
Based on these assumptions, new valency entries are constructed for words in a plain bilingual dictionary, using entries with
similar source-language meaning and the same target-language translations. We evaluate the effects of various measures of
semantic similarity. 相似文献
176.
A distributed model predictive control (DMPC) framework is proposed. The physical plant structure and the plant mathematical model are used to partition the system into self-sufficient estimation and control nodes. Local measurements at the nodes are used to estimate the relevant plant states. This information is then used in the model predictive control calculations. Communication among relevant nodes during estimation and control calculations provides improvement over the performance of completely decentralized controllers. The DMPC framework is demonstrated for the level control of an experimental four-tank system. The performance of the DMPC system for disturbance rejection is compared with other control configurations. The results indicate that the proposed framework provides significant improvement over completely decentralized MPC controllers, and approaches the performance of a fully centralized design. 相似文献
177.
The influence of emotional dissonance and resources at work on job burnout among Chinese human service employees. 总被引:1,自引:0,他引:1
The authors extended Hobfoll's Conservation of Resources (COR) model to examine the influence of emotional dissonance and work resources on burnout among 392 Chinese human service employees. Bivariate correlation results showed that emotional dissonance correlated positively with display rules and burnout, but negatively with work resources, specifically, satisfactory work relations and job rewards. Results of structural equation modeling analyses supported the extension of the COR model to study the dissonance-resources-burnout association. In the revised model, display rules had a direct impact on emotional dissonance, which in turn influenced burnout indirectly through the mediation of work resources. Limitations of the study and implications for work stress management are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
178.
McGlone Francis; Vallbo Ake B.; Olausson Hakan; Loken Line; Wessberg Johan 《Canadian Metallurgical Quarterly》2007,61(3):173
Somatic sensation comprises four main modalities, each relaying tactile, thermal, painful, or pruritic (itch) information to the central nervous system. These input channels can be further classified as subserving a sensory function of spatial and temporal localization, discrimination, and provision of essential information for controlling and guiding exploratory tactile behaviours, and an affective function that is widely recognized as providing the afferent neural input driving the subjective experience of pain, but not so widely recognized as also providing the subjective experience of affiliative or emotional somatic pleasure of touch. The discriminative properties of tactile sensation are mediated by a class of fast-conducting myelinated peripheral nerve fibres--A-beta fibres--whereas the rewarding, emotional properties of touch are hypothesized to be mediated by a class of unmyelinated peripheral nerve fibres--CT afferents (C tactile)--that have biophysical, electrophysiological, neurobiological, and anatomical properties that drive the temporally delayed emotional somatic system. CT afferents have not been found in the glabrous skin of the hand in spite of numerous electrophysiological explorations of this area. Hence, it seems reasonable to conclude that they are lacking in the glabrous skin. A full understanding of the behavioural and affective consequences of the differential innervation of CT afferents awaits a fuller understanding of their function. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
179.
New elementary farfield and nearfield time-harmonic water waves, observed from a Galilean reference frame, are given. These
two related classes of waves are modifications of classical elementary plane waves that are obtained in a simple way, using
only elementary fundamental considerations, by analyzing waves that slowly grow from rest at time T = −∞ and are bounded in the farfield. This approach circumvents the need for a radiation condition, which may indeed be regarded
as (indirectly) satisfied ab initio by the elementary farfield and nearfield waves given here. The farfield waves are the
product of classical elementary waves by a function, called radiation function, that is defined explicitly in terms of the
dispersion function. Thus, this radiation function is valid not only for water waves, but more generally for a broad class
of linear dispersive waves. For illustration and verification purposes, elementary stationary-phase considerations are used
to determine the main properties (phase and group velocities, wave patterns, asymptote and cusp lines) of farfield waves,
and two particular classes of water waves—steady ship waves and time-harmonic waves generated by an offshore structure—in
uniform finite water depth are considered. The elementary nearfield waves can readily be used to construct free-surface Green
functions or in a spectral representation of nearfield flows. 相似文献
180.
Sónia Cláudia Vitorino Cristina Gerald Francis Moore Priscila Raquel Fernandes Costa Goela John David Icely Alice Newton 《International journal of remote sensing》2013,34(6):2347-2377
Water-leaving reflectance (ρw) data from the European Space Agency ocean colour sensor Medium Resolution Imaging Spectrometer (MERIS) was validated with in situ ρw between October 2008 and November 2011, off Sagres on the southwest coast of the Iberian Peninsula. The study area is exceptional, since Stations A, B, and C at 2, 10, and 18 km offshore are in optically deep waters at approximately 40, 100, and 160 m, respectively. These stations showed consistently similar bio-optical properties, characteristic of Case 1 waters, enabling the evaluation of adjacency effects independent of the usual co-varying inputs of coastal waters. Using the third reprocessing of MERIS with the standard MEGS 8.1 processor, four different combinations of procedures were tested to improve the calibration between MERIS products and in situ data. These combinations included no vicarious adjustment (NoVIC), vicarious adjustment (VIC), and, for mitigating the effects of land adjacency on MERIS ρw, the improved contrast between ocean and land (ICOL) processor (version 2.7.4) and VIC + ICOL. Out of approximately 130 potential matchups for each station, 38–77%, 74–86%, and 88–90% were achieved at Stations A, B, and C, respectively, depending on which of the four combinations were used. Analyses of ρw comparing these various procedures, including statistics, scatter plots, histograms, and MERIS full-resolution images, showed that the VIC procedure compared with NoVIC produced minimal changes to the calibration. For example, at the oceanic Station C, the regression slope was closer to unity at all wavelengths with NoVIC compared to VIC, whereas, with the exception of wavelengths 412 and 443 nm, the intercept, mean ratio (MR), absolute percentage difference (APD), and relative percentage difference (RPD) were better with NoVIC. The differences for MR and APD indicate that there was marginal improvement for these two bands with VIC, and an over-adjustment with RPD. ICOL also showed inconsistent results for improving the retrieval of the near-shore conditions, but under some conditions, such as ρw at wavelength 560 nm, the improvement was striking. VIC + ICOL showed results intermediate between those of VIC and ICOL implemented separately. In relation to other validation sites, the offshore Station C at Sagres had much in common with the Mediterranean deep water, BOUSSOLE buoy, although the matchup statistics between MERIS ρw and in situ ρw were much better for Sagres than for BOUSSOLE. Strikingly, the matchup statistics for ρw at Sagres were very similar to those for the Acqua Alta Oceanographic Tower (AAOT), where the AAOT showed more scatter at 412 nm, probably because of the atmospheric correction where the aerosol optical thickness is higher at the AAOT. Conversely, Sagres showed much greater scatter at 665 nm in the red as the values were generally close to the limits of detection owing to the clearer waters at Sagres compared to the more turbid waters at the AAOT. 相似文献