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Analyzing the Educational Impacts of a New Mobile Application to Aid Student Learning of Electric Fields
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Brownian dynamics simulations of sphere clusters in optical tweezers
No full text© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement Computationally modeling the behavior of wavelength-sized non-spherical particles in optical tweezers can give insight into the existence and stability of trapping equilibria as well as the optical manipulation of such particles more broadly. Here, we report Brownian dynamics simulations of non-spherical particles that account for detailed optical, hydrodynamic, and thermal interactions. We use a T-matrix formalism to calculate the optical forces and torques exerted by focused laser beams on clusters of wavelength-sized spheres, and we incorporate detailed diffusion tensors that capture the anisotropic Brownian motion of the clusters. For two-sphere clusters whose size is comparable to or larger than the wavelength, we observe photokinetic effects in elliptically-polarized beams. We also demonstrate that multiple trapping equilibria exist for a highly asymmetric chiral cluster of seven spheres. Our simulations may lead to practical suggestions for optical trapping and manipulation as well as a deeper understanding of the underlying physics
Reflections from the editors on the occasion of the 75th anniversary of the Gerontological Society of America
No full textImplications for evolutionary trends from the pairing frequencies among golden-winged and blue-winged warblers and their hybrids
No full text© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd Extensive range loss for the Golden-winged Warbler (Vermivora chrysoptera) has occurred in areas of intrusion by the Blue-winged Warbler (V. cyanoptera) potentially related to their close genetic relationship. We compiled data on social pairing from nine studies for 2,679 resident Vermivora to assess evolutionary divergence. Hybridization between pure phenotypes occurred with 1.2% of resident males for sympatric populations. Pairing success rates for Golden-winged Warblers was 83% and for Blue-winged Warblers was 77%. Pairing success for the hybrid Brewster\u27s Warbler was significantly lower from both species at 54%, showing sexual selection against hybrids. Backcross frequencies for Golden-winged Warblers at 4.9% were significantly higher than for Blue-winged Warblers at 1.7%. More frequent backcrossing by Golden-winged Warblers, which produces hybrid phenotypes, may contribute to the replacement of Golden-winged by Blue-winged Warblers. Reproductive isolation due to behavioral isolation plus sexual selection against hybrids was 0.960. Our analyses suggest that plumage differences are the main driving force for this strong isolation with reduced hybrid fitness contributing to a lesser degree. The major impact of plumage differences to reproductive isolation is compatible with genomic analyses (Current Biology, 2016, 26, 2313), which showed the largest genetic difference between these phenotypes occurred with plumage genes. These phenotypes have maintained morphological, behavioral, and ecological differences during two centuries of hybridization. Our estimate of reproductive isolation supports recognition of these phenotypes as two species. The decline and extirpation of the Golden-winged Warbler in almost all areas of recent sympatry suggest that continued coexistence of both species will require eco-geographic isolation
Supporting and Recognizing Excellence in Teaching: STP at 75
No full text© The Author(s) 2020. Established in 1945 as Division 2, one of the original divisions of the American Psychological Association, the Society for the Teaching of Psychology (STP) celebrates its 75th anniversary in 2020. On the occasion of STP’s 50th anniversary, Wight and Davis published a history of the Division’s first 50 years. Using that history, we summarize STP’s first 50 years and then focus on developments and changes during the last 25 years. We believe that STP has experienced greater change and growth in the last 25 years than it did in the first 50 years
Lingering Effects of Prenatal Alcohol Exposure on Basal and Ethanol-Evoked Expression of Inflammatory-Related Genes in the CNS of Adolescent and Adult Rats
No full text© Copyright © 2020 Doremus-Fitzwater, Youngentob, Youngentob, Gano, Vore and Deak. Emerging data suggest that alcohol’s effects on central inflammatory factors are not uniform across the lifespan. In particular, prenatal alcohol exposure (PAE) significantly alters steady-state levels of neuroimmune factors, as well as subsequent reactivity to later immune challenge. Thus, the current experiment investigated developmental sensitivities to, and long-lasting consequences of, PAE on ethanol-evoked cytokine expression in male and female adolescent and adult rats. Pregnant dams received either an ad libitum ethanol liquid diet (2.2% GD 6–8; 4.5% GD 9–10; 6.7% GD11–20; 35% daily calories from ethanol) or free-choice access to a control liquid diet and water. At birth, offspring were fostered to dams given free-choice access to the control liquid diet. Pups then matured until mid-adolescence [postnatal day (PD) 35] or adulthood (PD90), at which time they were challenged with either a binge-like dose of ethanol (4 g/kg; intragastrically) or tap water. During intoxication (3 h post-ethanol challenge), brains and blood were collected for assessment of neuroimmune gene expression (reverse transcription-polymerase chain reaction; RT-PCR) in the hippocampus, amygdala, and PVN, as well as for blood ethanol concentrations (BEC) and plasma corticosterone levels. Results revealed that rats challenged with ethanol at either PD35 or PD90 generally exhibited a characteristic cytokine signature of acute intoxication that we have previously reported: increased Il-6 and IkBα expression, with decreased Il-1β and Tnfα gene expression. With a few exceptions, this pattern of gene changes was observed in all three structures examined, at both ages of postnatal ethanol challenge, and in both sexes. While few significant effects of PAE were observed for ethanol-induced alterations in cytokine expression, there was a consistent (but nonsignificant) trend for PAE to potentiate the expression of Il-6 and IkBα in all groups except adult females. Although these data suggest that later-life ethanol challenge was a far greater driver of inflammatory signaling than PAE, the current results demonstrate PAE resulted in subtle long-term alterations in the expression of many key neuroinflammatory factors associated with NF-κB signaling. Such long-lasting impacts of PAE that may engender vulnerability to later environmental events triggering neuroinflammatory processes, such as chronic ethanol exposure or stress, could contribute to heightened vulnerability for PAE-related alterations and deficits
The impact of leader communication on free-riding: An incentivized experiment with empowering and directive styles
No full text© 2019 Elsevier Inc. Organizations often appoint leaders to foster cooperation. This paper studies the effect of leader communication on free-riding behavior using controlled and incentivized experiments. Leaders are asked to choose public messages from a set that induces a particular leadership style and to send them to subjects matched in groups to play a repeated, finite-horizon public good game. Using a between-subjects design, empowering and directive message sets are studied. Treatments are implemented with and without opportunities for two-way leader follower communication to study the impact of free-form communication. In the absence of opportunities for two-way leader follower communication, leaders assigned to the empowering messages treatment are more effective in mitigating free-riding than leaders assigned to the directive messages treatment. In its presence, contributions in both treatments are higher. The design allows for the study of a more interactive form of directive leadership by combining directive public messages with two-way leader follower communication