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In Study One, a sample of 230 college students were asked to estimate the abuse potential and lethality of commonly used recreational drugs, both licit and illicit. In Study Two, a sample of 103 degreed nurses were asked to estimate the lethality of the same recreational drugs. The findings indicate that the illicit drugs under consideration are perceived as presenting the greatest danger to the user and that dangers attributed to the use of licit recreational drugs are generally minimized. Perception of danger was found to be unaffected by exposure to reported drug education programs. Results are discussed in terms of public health implications. 相似文献
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Detailed Real-Time Urban 3D Reconstruction from Video 总被引:2,自引:0,他引:2
M. Pollefeys D. Nistér J.-M. Frahm A. Akbarzadeh P. Mordohai B. Clipp C. Engels D. Gallup S.-J. Kim P. Merrell C. Salmi S. Sinha B. Talton L. Wang Q. Yang H. Stewénius R. Yang G. Welch H. Towles 《International Journal of Computer Vision》2008,78(2-3):143-167
The paper presents a system for automatic, geo-registered, real-time 3D reconstruction from video of urban scenes. The system
collects video streams, as well as GPS and inertia measurements in order to place the reconstructed models in geo-registered
coordinates. It is designed using current state of the art real-time modules for all processing steps. It employs commodity
graphics hardware and standard CPU’s to achieve real-time performance. We present the main considerations in designing the
system and the steps of the processing pipeline. Our system extends existing algorithms to meet the robustness and variability
necessary to operate out of the lab. To account for the large dynamic range of outdoor videos the processing pipeline estimates
global camera gain changes in the feature tracking stage and efficiently compensates for these in stereo estimation without
impacting the real-time performance. The required accuracy for many applications is achieved with a two-step stereo reconstruction
process exploiting the redundancy across frames. We show results on real video sequences comprising hundreds of thousands
of frames. 相似文献
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The Boolean Vector Machine (BVM) is a large network of extremely small processors with very small memories operating in SIMD mode using bit serial arithmetic. Individual processors communicate via a hardware implementation of the Cube Connected Cycles (CCC) network. A prototype BVM with 2048 processing elements, each with 200 binary bits of memory, is currently being built using VLSI technology.
The BVM's bit-serial arithmetic and the small memories of individual processors are apparently a drawback to its effectiveness when applied to large numerical problems. In this paper we analyze an implementation of a basic matrix-vector iteration algorithm for sparse matrices on the BVM. We show that a 220 Pe BVM can deliver over 1 billion (109) useful floating-point operations per second for this problem. The algorithm is expressed in a new language (BVL) which has been defined for programming the BVM. 相似文献
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This investigation consolidated the recent research on gender differences in self-concept among children and youth by conducting a systematic meta-analysis of research published since 1980, particularly involving self-concept as a multidimensional phenomenon. Through a comprehensive search process, 22 studies representing over 19,000 child and adolescent participants were analyzed. The articles included participant samples from 7 nations: the US, Australia, Northern Ireland, South Africa, Finland, Norway, and Canada. Participants ranged from 1st grade through 12th grade. Mean effect size estimates across dimensions showed a complex pattern of gender differences and similarities, some of which were consistent across grade levels and others of which were not. Although some of the findings defied stereotypes, several were consistent with previous notions regarding differences in self-concept based on gender. The direction and complexity of these results emphasizes the importance of discussing developmental differences in self-concept in a thoughtful and careful manner and argues against the use of simplistic global generalizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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In order to determine changes in breathing patterns brought about by resistive loading, ventilation was recorded in 11 healthy subjects with four linear resistances (3.57, 5.75, 8.76 and 13.13 cmH2O L(-1) sec) added in a random order throughout the entire breath. At steady state, a breath-by-breath analysis of airflow was used to quantify the pattern of breathing in terms of respiratory variables: TI, TE, Tt, VT, VT/TI, TI/Tt, and by taking TI, TE, VT all together (TRIAD) and also the shape of the entire airflow profile quantified by harmonic analysis (ASTER). Group analysis using ANOVA showed significant changes in all variables. There were increasing changes with increasing loads in all variables, the smallest changes being in TI/Tt. Within to between-individual comparisons between two loads showed that only TI/Tt and the ASTER were more similar within than between-individuals for all comparisons. It was concluded that at steady state mechanisms of load compensation come into play inducing changes in the pattern of breathing proportional to the loads while maintaining some of the individual characteristics. 相似文献
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Solving large, sparse, linear systems of equations is a fundamental problems in large scale scientific and engineering computation. A model of a general class of asynchronous, iterative solution methods for linear systems is developed. In the model, the system is solved by creating several cooperating tasks that each compute a portion of the solution vector. A data transfer model predicting both the probability that data must be transferred between two tasks and the amount of data to be transferred is presented. This model is used to derive an execution time model for predicting parallel execution time and an optimal number of tasks given the dimension and sparsity of the coefficient matrix and the costs of computation, synchronization, and communication.The suitability of different parallel architectures for solving randomly sparse linear systems is discussed. Based on the complexity of task scheduling, one parallel architecture, based on a broadcast bus, is presented and analyzed. 相似文献
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The advent of telehealth technology gives psychologists new opportunities to expand their practices in a cost-effective manner, but little is known about telehealth efficacy and costs. This study of 49 neuropsychology clients interviewed using videoconferencing and 49 matched in-person controls yielded no group differences in client ratings of interpersonal factors. Telehealth clients were more likely to want to repeat their experience, but psychologist satisfaction was lower for telehealth sessions. Telehealth costs were significantly lower than in-person costs. Concerns about ethical issues, billing, and licensure must be addressed to help practitioners capitalize on new telehealth opportunities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献