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31.
This study examined the behavioral differences among liked and disliked hyperactive children and their normal peers during joint activities. 25 hyperactive children and 39 normal control subjects were selected and observed in high- and low-structured play settings (counterbalanced for order) in one of 3 dyadic groupings (10 liked hyperactive children, each with a control; 15 disliked hyperactive children, each with a control; and 7 control–control pairs). For the most part, the differences observed did not depend on setting or gender comparisons. Hyperactive children were more active, talkative, and physically off-task than their peers, but they made fewer positive social statements. Disliked hyperactive children made more negative statements with accompanying negative physical interactions. Specifically, in response to disliked hyperactive children, normal partners became more negative and active, were less talkative and cooperative, and engaged in more solitary play than when playing with other normal children. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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33.
In this second of a two-part article, we describe how the therapist's interpretations promote therapeutic progress. Any therapist behavior that is in accord with the patient's plan will be helpful to the patient, but interventions that are at cross purposes with the patient's plan will not be helpful. The implications of the plan concept for brief dynamic therapy are described and contrasted with other key technical, concepts such as transference interpretations, therapeutic alliance, and interpretive activity. The importance of understanding the patient's plan and intervening in accord with it are illustrated in several case vignettes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
34.
Failure recovery in a multidatabase environment is addressed. It is shown that local autonomy considerations force the designer of a multidatabase system to trade off certain desirable properties to achieve reliability for transaction management. Representative techniques in the research literature are contrasted and compared. The author's approach to the problem is described 相似文献
35.
Summary The Synchronization primitive P
* was introduced by Conradi in order to present a more compact and efficient algorithm for synchronization of concurrent readers and writers. Unfortunately, Conradi's solutions fail when the conventional definitions of semaphores are used in conjunction with this primitive. This paper proposes a definition of the semaphore operations P, V and P
* that make Conradi's readers-writers solutions correct. This definition is compatible with the definition given by Dijkstra.This work was partially supported by the National Science Foundation Grant Number MCS7702463 相似文献
36.
37.
A mathematical model of simultaneous mass, heat and momentum transfer for two-phase flow of a gas and a solid/liquid slurry was developed. The model was applied to calculation of the drying process of coal-water slurry droplets in a gas medium in a steady one-dimensional flow. The model was based on the well-known two-stage drying process for slurry droplets. After the first period of drying, in which the evaporation rate is controlled by the gas phase resistance, the evaporating liquid diffuses through the porous shell (crust) and then, by convection, into the gas medium. Inside the dry external crust of the drop, a wet central core forms, which shrinks as evaporation proceeds. The temperature of the slurry droplet rises. The process ends when the temperature of the dry outer crust reaches the coal ignition temperature in the case of combustion or when the moisture of the particle reaches the final required moisture. The developed model was based on one-dimensional balance equations of mass, energy and momentum for the liquid/solid and gas phases. The system of governing equations was represented by first-order differential equations and solved simultaneously. The numerical solution of the governing equations was obtained using Gear's method. The model permitted calculation 相似文献
38.
Mariposa: a wide-area distributed database system 总被引:7,自引:0,他引:7
Michael Stonebraker Paul M. Aoki Witold Litwin Avi Pfeffer Adam Sah Jeff Sidell Carl Staelin Andrew Yu 《The VLDB Journal The International Journal on Very Large Data Bases》1996,5(1):48-63
The requirements of wide-area distributed database systems
differ dramatically from those of local-area network systems. In a
wide-area network
(WAN) configuration, individual sites usually report to different system
administrators, have different access and charging algorithms, install
site-specific data type extensions, and have different constraints on
servicing remote requests. Typical of the last point are production
transaction environments, which are fully engaged during normal
business hours, and cannot take on additional load. Finally, there
may be many sites participating in a WAN distributed DBMS.
In this world, a single program performing global query
optimization using a cost-based optimizer will not work well.
Cost-based optimization does not respond well to site-specific type
extension, access constraints, charging algorithms, and time-of-day
constraints. Furthermore, traditional cost-based distributed
optimizers do not scale well to a large number of possible processing
sites. Since traditional distributed DBMSs have all used cost-based
optimizers, they are not appropriate in a WAN environment, and a new
architecture is required.
We have proposed and implemented an economic paradigm as the
solution to these issues in a new distributed DBMS called Mariposa.
In this paper, we present the architecture and implementation of
Mariposa and discuss early feedback on its operating characteristics.
Edited by Henry F. Korth and Amith Sheth.
Received November 1994 / Revised June 1995
/ Accepted September 14, 1995 相似文献
39.
Beate Pscheidt Zhibin Liu Richard Gaisberger Manuela Avi Wolfgang Skranc Karl Gruber Herfried Griengl Anton Glieder 《Advanced Synthesis \u0026amp; Catalysis》2008,350(13):1943-1948
Screening for stereoselective cyanohydrin synthesis in 96‐well plates was employed in the development of an efficient, pH‐stable hydroxynitrile lyase for the conversion of sterically hindered aliphatic aldehydes. Site‐saturation mutagenesis (SSM) resulted in a powerful catalyst for the stereoselective conversion of hydroxypivalaldehyde and pivalaldehyde to their corresponding (R)‐cyanohydrins (ee >97%) which are used as chiral building blocks (e.g., for pantothenic acid production). Furthermore, redesigning the PaHNL5 gene and improving its expression by Pichia pastoris with the help of a new PAOX1 promoter variant and the helper protein PDI (protein disulfide isomerase) led to elevated amounts of today’s most efficient biocatalyst for vitamin B5 synthesis. 相似文献
40.