Particle motion in Stokes flow near a plane fluid-fluid interface. Part 1. Slender body in a quiescent fluid

The present study examines the motion of a slender body in the presence of a plane fluid–fluid interface with an arbitrary viscosity ratio. The fluids are assumed to be at rest at infinity, and the particle is assumed to have an arbitrary orientation relative to the interface. The method of analysis is slender-body theory for Stokes flow using the fundamental solutions for singularities (i.e. Stokeslets and potential doublets) near a flat interface. We consider translation and rotation, each in three mutually orthogonal directions, thus determining the components of the hydrodynamic resistance tensors which relate the total hydrodynamic force and torque on the particle to its translational and angular velocities for a completely arbitrary translational and angular motion. To illustrate the application of these basic results, we calculate trajectories for a freely rotating particle under the action of an applied force either normal or parallel to a flat interface, which are relevant to particle sedimentation near a flat interface or to the processes of particle capture via drop or bubble flotation

The Researcher Social Network: a social network based on metadata of scientific publications

Scientific journals can capture a scholar’s research career. A researcher’s publication data often reflects his/her research interests and their social relations. It is demonstrated that scientist collaboration networks can be constructed based on co-authorship data from journal papers. The problem with such a network is that researchers are limited within their professional social network. This work proposes the idea of constructing a researcher’s social network based on data harvested from metadata of scientific publications and personal online profiles. We hypothesize that data, such as, publication keywords, personal interests, the themes of the conferences where papers are published, and co-authors of the papers, either directly or indirectly represent the authors’ research interests, and by measuring the similarity between these data we are able to construct a researcher social network. Based on the four types of data mentioned above, social network graphs were plotted, studied and analyzed. These graphs were then evaluated by the researchers themselves by giving ratings. Based on this evaluation, we estimated the weight for each type of data, in order to blend all data together to construct one ideal researcher’s social network. Interestingly, our results showed that a graph based on publication’s keywords were more representative than the one based on publication’s co-authorship. The findings from the evaluation were used to propose a dynamic social network data model

The effect of grade retention on academic and social-behavioral outcomes for students with disabilities in elementary grades

There is a lack of research examining the rates and effect of grade retention, a widely used intervention at schools, among students with disabilities. The existing research evidence of retention effects among students without disabilities remains inconclusive, which might result from the differences in analytical methodologies, sample selections and measurement errors. The purpose of the present study was to examine the retention rates, academic and behavioral trajectories of retained versus promoted students with disabilities, and the effect of grade retention for students with disabilities using the nationally representative Special Education Elementary Longitudinal Study (SEELS) dataset. Hierarchical linear modeling (HLM) was conducted to investigate the trajectories of being retained at three different time points (kindergarten, first and second grade) on later academic and social development trajectories among students with disabilities (N = 13,176). Propensity score matching (PSM) was used to infer causal inferences by creating two equivalent groups matched on a set of baseline measures. Results indicated that retention rates for students with disabilities are much higher than that for students without disabilities reported in previous studies. In addition, retention rates differ, albeit slightly, by student demographic characteristics such as race, gender, EL status, family income and disability types. Retained students with disabilities do not differ significantly from their promoted peers in terms of academic and behavioral trajectories with an exception of mathematics at kindergarten. The analysis of propensity score matching indicated that there is no effect of grade retention on reading performances but retention results in significant worse math performances for students with disabilities.Special Educatio