Reading Motivation: Multidimensional and Indeterminate.

The Motivations for Reading Questionnaire (MRQ) contains 54 items that are posited to tap 11 dimensions of reading motivation. The structural validity of the MRQ was investigated with 2 samples: (a) 328 students in Grades 3-5 from 2 suburban mid-Atlantic elementary schools and (b) 735 students in Grades 3-5 in 2 suburban southwestern elementary schools. With confirmatory factor analyses (CFAs), the theoretical 11-factor structure did not adequately fit the data in either sample. Subsequently, exploratory factor analyses found 8 factors for each sample with 6 factors defined by only 3 or 4 common items. However, a double CFA cross-validation found an inadequate fit for both samples. Given these results, the authors suggest that the MRQ be revised. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heterogeneity in Youth Symptom Trajectories Following Psychiatric Crisis: Predictors and Placement Outcome.

The authors examined heterogeneity in symptom trajectories among youths following psychiatric crises as well as the psychosocial correlates and placement outcomes associated with identified trajectories. Using semiparametric mixture modeling with 156 youths approved for psychiatric hospitalization, the authors identified 5 trajectories based on symptoms over the 16 months following crisis: high improved, high unimproved, borderline improved, borderline unimproved, and subclinical. Membership in unimproved symptom groups was associated with less suicidality, younger age, more youth hopelessness, and more caregiver empowerment. Improved symptom group membership predicted long-term decreases in days in out-of-home placements. More important, and in contrast with general impressions from the existing literature, findings suggest that a substantive proportion of youths with serious emotional disturbance sustain high levels of symptomatology following intensive mental health services. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Steady-state response of the parametrically excited axially moving string constituted by the Boltzmann superposition principle

Summary.  The steady-state transverse vibration of a parametrically excited axially moving string with geometric nonlinearity is investigated in this paper. The Boltzmann superposition principle is employed to characterize the material property of the string. The method of multiple scales is applied directly to the governing equation, which is a nonlinear partial-differential-integral equation. The solvability condition of eliminating the secular terms is established. Closed form solutions for the amplitude and the existence conditions of nontrivial steady-state response of the summation resonance are obtained. Some numerical examples showing effects of the viscoelastic parameter, the amplitude of excitation, the frequency of excitation, and the transport speed are presented. Received February 12, 2002; revised October 25, 2002 Published online: May 8, 2003 The research was supported by the National Natural Science Foundation of China (Project No. 10172056).     

Finite element analysis of electromagnetic scattering from a cavity

A finite element method (FEM) is implemented to compute the radar cross section of a two-dimensional (2D) cavity embedded in an infinite ground plane. The method is based on the variational formulation which uses the Fourier transform to couple the fields outside the cavity and those inside the cavity; hence, the scattering problem can be reduced to a bounded domain. The convergence of the discrete finite element problem is analyzed. Numerical results are presented and compared with those obtained by the standard finite element-Green function method and by the 2D integral equation method.     

Sputtering mechanisms near the threshold energy

Threshold energies for sputtering cannot be calculated directly but have to be evaluated from the energy dependence of the sputtering yields. This paper investigates trajectories of projectile and recoils near the threshold energy for sputtering, where the collision cascade becomes increasingly simple. Statistics of the different collision events show which processes dominate the sputtering close to the threshold energy for selfbombardment of different light and heavy targets. The differential cross-sections for scattering and recoil production explain qualitatively the probability for the various processes.     

Implicit Motor Learning in Parkinson's Disease.

Objective: This study examined whether disruption of performance is moderated in Parkinson's disease (PD) patients who acquire their motor behaviors in an implicit manner. Method: Twenty-seven patients with PD learned a hammering task in errorless (implicit) or errorful (explicit) conditions and were tested for robustness of motor performance under a secondary task load, which required them to continuously count backward as they performed the hammering task. Results: Patients in the errorless (implicit) motor learning condition exhibited robustness to secondary task loading, whereas patients in the errorful (explicit) motor learning condition did not. Conclusions: Implicit motor learning techniques should be considered by PD rehabilitation specialists in cases in which existing disruption to movements is exacerbated by conscious control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mining constrained gradients in large databases

Many data analysis tasks can be viewed as search or mining in a multidimensional space (MDS). In such MDSs, dimensions capture potentially important factors for given applications, and cells represent combinations of values for the factors. To systematically analyze data in MDS, an interesting notion, called "cubegrade" was recently introduced by Imielinski et al. [2002], which focuses on the notable changes in measures in MDS by comparing a cell (which we refer to as probe cell) with its gradient cells, namely, its ancestors, descendants, and siblings. We call such queries gradient analysis queries (GQs). Since an MDS can contain billions of cells, it is important to answer GQs efficiently. We focus on developing efficient methods for mining GQs constrained by certain (weakly) antimonotone constraints. Instead of conducting an independent gradient-cell search once per probe cell, which is inefficient due to much repeated work, we propose an efficient algorithm, LiveSet-Driven. This algorithm finds all good gradient-probe cell pairs in one search pass. It utilizes measure-value analysis and dimension-match analysis in a set-oriented manner, to achieve bidirectional pruning between the sets of hopeful probe cells and of hopeful gradient cells. Moreover, it adopts a hypertree structure and an H-cubing method to compress data and to maximize sharing of computation. Our performance study shows that this algorithm is efficient and scalable. In addition to data cubes, we extend our study to another important scenario: mining constrained gradients in transactional databases where each item is associated with some measures such as price. Such transactional databases can be viewed as sparse MDSs where items represent dimensions, although they have significantly different characteristics than data cubes. We outline efficient mining methods for this problem.     

A Multilayer Optical Packet Switching Network Based on the Kautz Graph and Optical Passive Star Couplers

The multihop optical network is the most appropriate solution to satisfy the increasing applications of Internet services. This paper extends the regular Kautz graph to one with multiple layers in order to produce more architectural variations. The connectivity between adjacent layers utilizes the systematic connection patterns of a regular Kautz graph. A routing algorithm based on its property is presented. Optical passive star (OPS) couplers are adopted to implement our new topologies. Three scheduling criteria that can solve the contention problem in the intermediate nodes are evaluated and compared in terms of their capability to improve the accessibility.