A nontrivial subset of the jammed packings for rigid disks and spheres are those that can be obtained by sequential removal of particles from periodic crystalline arrays. This paper considers the enumeration problems presented by such packings that are based on the close-packed triangular disk lattice, and the face-centered and body-centered cubic sphere lattices. Three distinct categories of p...

BACKGROUND Treatment for suicidality can be delivered online, but evidence for its effectiveness is needed. OBJECTIVE The goal of our study was to examine the effectiveness of an online self-help intervention for suicidal thinking compared to an attention-matched control program. METHODS A 2-arm randomized controlled trial was conducted with assessment at postintervention, 6, and, 12 months...

This study examines attrition rates over the first four years of the New Zealand Attitudes and Values Study, a longitudinal national panel sample of New Zealand adults. We report the base rate and covariates for the following four distinct classes of respondents: explicit withdrawals, lost respondents, intermittent respondents and constant respondents. A multinomial logistic regression examined...

The artificial language Esperanto is spoken not only as a second language, by its proponents, but also as a native language by children of some of those proponents. The present study is a preliminary description of some characteristics of the Native Esperanto (NE) of eight speakers, ranging in age from six to fourteen years. As such, it is the first of its kind--previous works on NE are either ...

OBJECTIVES Identify characteristics distinguishing people who do and do not continue to participate in a longitudinal study and determine whether the longitudinal changes for people who continue are representative of the changes that would have occurred had longitudinal data been available from all of the initial participants. METHOD Moderately large samples of returning (N = 2,082) and nonre...

A delay in PhD completion, while likely undesirable for PhD candidates, can also be detrimental to universities if and when PhD delay leads to attrition/termination. Termination of the PhD trajectory can lead to individual stress, a loss of valuable time and resources invested in the candidate and can also mean a loss of competitive advantage. Using data from two studies of doctoral candidates ...

Does volunteer participation reduce depressive symptoms among older people? Does depression influence whether older people will volunteer? Might nonrandom attrition in a longitudinal study bias the relationship between volunteering and depression? This research addresses these questions with three-wave data from theAmericans' Changing Lives study. Multigroup structural equation models for compl...

Visualizing a three-dimensional relation among an exposure, an outcome, and a third factor is complicated, particularly when students are first being introduced to epidemiologic methods. The heuristic device described below can be used by teachers of epidemiology to help introductory students understand how a third factor will affect the association between an exposure and an outcome. The devic...

With so much emphasis on reducing attrition and becoming more efficient in the delivery of healthcare, there are many opportunities to leverage existing clinical data in drug development and to foster the practice of reverse translation. The application of quantitative approaches to convert clinical trial and real-world data to knowledge will continue to drive innovation. Herein we discuss rece...

A group of crossbred Dorset or Finnish Landrace ewes maintained under a synthetic light regimen (Light Treatment, 4 mo long days - 16 h light, 4 mo short days - 8 h light) and exposed to rams every 8 mo (January 1, September 1, May 1) was compared for lamb production over a period of 4.5 yr with two other comparable groups under natural daylight conditions, one exposed to rams once a year in th...