The differential expression of male sexual behavior in the Lewis, Fischer and Sprague-Dawley rat strains

Several indices of sexual behavior were characterized for male rats of the Lewis (LEW), Sprague-Dawley (SD) and Fischer (F344) strains. Males were permitted access to a receptive female of their own strain for five 50-min sessions every fifth day. LEW males emitted longer latencies (first mount, intromission, ejaculation and post-ejaculatory interval) and lower frequencies (mounts, intromissions, ejaculations, intromission ratio) relative to F344 males, with the SD strain in general, lying intermediate. Following this assessment, males of each strain were randomly assigned to females of their own or another strain to ascertain whether differences were due to differential female receptivity. Although there were no significant differences during this phase indicative of differential receptivity, the sample size may preclude a definitive interpretation of such results. The data were discussed in the context of other behavioral differences between the strains and the possible neurobiological mechanisms underlying these differences.     

Mental Rotation With Tangible Three‐Dimensional Objects: A New Measure Sensitive to Developmental Differences in 4‐ to 8‐Year‐Old Children

There is an emerging consensus that spatial thinking is fundamental to later success in math and science. The goals of this study were to design and evaluate a novel test of three‐dimensional (3D) mental rotation for 4‐ to 8‐year‐old children (N = 165) that uses tangible 3D objects. Results revealed that the measure was both valid and reliable and indicated steady growth in 3D mental rotation between the ages of 4 and 8. Performance on the measure was highly related to success on a measure of two‐dimensional (2D) mental rotation, even after controlling for executive functioning. Although children as young as 5 years old performed above chance, 3D mental rotation appears to be a difficult skill for most children under the age of 7, as indicated by frequent guessing and difficulty with mirror objects. The test is a useful new tool for studying the development of 3D mental rotation in young children.     

Contactless microfluidic pumping using microchannel-integrated carbon black composite membranes

The ability to pump and manipulate fluid at the micron-scale is a basic requirement for microfluidic platforms. Many current manipulation methods, however, require expensive and bulky external supporting equipment, which are not typically compatible for portable applications. We have developed a contactless metal electro-osmotic micropump capable of pumping conductive buffers. The pump operates using two pairs of gallium metal electrodes, which are activated using an external voltage source and separated from a main flow channel by a thin micron-scale polydimethylsiloxane (PDMS) membrane. The thin contactless membrane allows for field penetration and electro-osmotic flow within the microchannel, but eliminates electrode damage and sample contamination commonly associated with traditional DC electro-osmotic pumps that utilize electrodes in direct contact with the working fluid. Our previous work has demonstrated the effectiveness of this method in pumping deionized water. However, due to the high resistivity of PDMS, this method proved difficult to apply towards manipulating conductive buffers. To overcome this limitation, we fabricated conductive carbon black (CB) powder directly into the contactless PDMS membranes. The increased electrical conductivity of the contactless PDMS membrane significantly increased micropump performance. Using a microfluidic T-channel device and an electro-osmotic flow model, we determined the influence that CB has on pump pressure for CB weight percents varying between 0 and 20. The results demonstrate that the CB increases pump pressure by two orders of magnitude and enables effective operations with conductive buffers.     

Kinematic effects of a short-term fatigue protocol on punt-kicking performance

The punt kick is a fundamental skill used in several team sports; however, there has been a lack of research on how fatigue affects its technique. The purpose of this study was to determine the effects of short-term fatigue on punt-kicking performance. Eight elite and sub-elite Australian Football players performed maximal drop punt kicks on their preferred leg prior to, during and after a match-specific fatigue protocol. Optotrak Certus collected kinematic data from kick foot toe-off until ball contact. Repeated-measures analysis of variance showed a significant increase in 20 m sprint times after each short-term protocol, indicating fatigue. Foot speed did not significantly change with fatigue; however, increases in the range of motion at the pelvis and kicking thigh, along with increases in kicking thigh angular velocity, occurred. For the support leg, maximum knee flexion angular velocity increased while there was greater flexion found at the knee and hip, and greater range of motion at the knee. Players are able to make kinematic adaptations in order to maintain foot speed while punting for maximal distance after short-term efforts.     

A Comparison of Three-Step Approaches for Auxiliary Variables in Latent Class and Latent Profile Analysis

In this article, 3-step methods to include predictors and distal outcomes in commonly used mixture models are evaluated. Two Monte Carlo simulation studies were conducted to compare the pseudo class (PC), Vermunt’s (2010), and the Lanza, Tan, and Bray (LTB) 3-step approaches with respect to bias of parameter estimates in latent class analysis (LCA) and latent profile analysis (LPA) models with auxiliary variables. For coefficients of predictors of class membership, results indicated that Vermunt’s method yielded more accurate estimates for LCA and LPA compared to the PC method. With distal outcomes of latent classes and latent profiles, the LTB method produced the lowest relative bias of coefficient estimates and Type I error rates close to nominal levels.     

The effect of deloading tape on medial gastrocnemius muscle fascicle behaviour during dynamic exercise

This study examined the effect of diamond deloading tape on medial gastrocnemius (MG) muscle behaviour during exercise in healthy adults (n = 27). A randomised cross-over trial assessed the effect of tape (no-tape, sham-tape and deload-tape) on ankle and MG fascicle kinematics during three heel raise-lower exercises [double leg (DL), single leg (SL) and loaded single leg (LSL)]. There was no effect of tape on standing fascicle length (FL) or pennation angle (PA), or ankle or knee joint angle. There was a significant effect of tape on ankle kinematics for all exercises. Both the deload-tape and sham-tape resulted in less ankle plantar flexion but had no effect on dorsiflexion. There was a significant effect of tape on FL change for the SL and LSL exercise. Compared to no-tape, the deload-tape resulted in less fascicle shortening during ankle plantar flexion, and more fascicle lengthening during ankle dorsiflexion. For the LSL exercise, deload-tape caused MG fascicles to operate at longer lengths, for a given joint angle. Diamond taping, with or without added tension, has only a small effect on ankle and MG fascicle kinematics during the heel raise-lower exercise. With the exception of the LSL exercise, both tape conditions resulted in similar changes in the FL-angle relations.     

Supporting Preschoolers and Their Families who are Recently Resettled Refugees

According to the United Nations High Commission for Refugees, the number of refugees worldwide was 10.5 million in 2009 and this number continues to grow (United Nations Refugee Agency, 2010 United Nations Refugee Agency. 2010. UNHRC—The U.N. Refugee Agency website Geneva, , Switzerland Retrieved February 4, 2010, from http://www.unhcr.org/pages/49c3646c2.html [Google Scholar]). There is a shortage of evidence based practices and information regarding the state of service provision for young refugee children and their families in preschool programs. In this qualitative study, 25 early childhood educators participated in semi-structured interviews to illuminate the experiences of teachers as they work with preschool children and families in a small New England refugee resettlement community. Themes identified were barriers and facilitators related to two main categories of communication issues and cultural complexities. Implications for future research, teacher preparation programs, professional development and early childhood programs are discussed.     

Modelling age and secular differences in fitness between basketball players

Concerns about the value of physical testing and apparently declining test performance in junior basketball players prompted this retrospective study of trends in anthropometric and fitness test scores related to recruitment age and recruitment year. The participants were 1011 females and 1087 males entering Basketball Australia's State and National programmes (1862 and 236 players, respectively). Players were tested on 2.6 +/- 2.0 (mean +/- s) occasions over 0.8 +/- 1.0 year. Test scores were adjusted to recruitment age (14-19 years) and recruitment year (1996-2003) using mixed modelling. Effects were estimated by log transformation and expressed as standardized (Cohen) differences in means. National players scored more favourably than State players on all tests, with the differences being generally small (standardized differences, 0.2-0.6) or moderate (0.6-1.2). On all tests, males scored more favourably than females, with large standardized differences (>1.2). Athletes entering at age 16 performed at least moderately better than athletes entering at age 14 on most tests (standardized differences, 0.7-2.1), but test scores often plateaued or began to deteriorate at around 17 years. Some fitness scores deteriorated over the 8-year period, most notably a moderate increase in sprint time and moderate (National male) to large (National female) declines in shuttle run performance. Variation in test scores between National players was generally less than that between State players (ratio of standard deviations, 0.83-1.18). More favourable means and lower variability in athletes of a higher standard highlight the potential utility of these tests in junior basketball programmes, although secular declines should be a major concern of Australian basketball coaches.