Assessing the Potential Threat of Widely Used Agrochemicals to Honey Bee (Apis mellifera L.) Drones and Workers

Honey bees (Apis mellifera) have been experiencing an ongoing decline in population over the last half century despite their tremendous importance to agriculture. A variety of environmental pressures have been implicated in this decline including pesticides commonly found within the hive and foraging environments. To assess the potential effect of exposure to in-hive pesticides on drone spermatozoa viability, we compared the viability of spermatozoa collected from drones reared in pesticide-free wax to that of drones reared in wax contaminated with field-relevant doses of several common agrochemicals, including chlorothalonil and chlorpyrifos, and miticides, including fluvalinate, coumaphos and amitraz. Our results suggest a significant negative effect of in-hive pesticide exposure during development on spermatozoa viability. The greatest risk of exposure to pesticides, however, is faced by a subset of workers, foragers, that function in food collection from floral resources. The activity of honey bee foragers contributes approximately $17 billion annually in pollination services for several major crops in the United States including almond, which is completely dependent on honey bees for pollination. To assess the effects of pesticides commonly used during almond bloom on honey bee forager survival, foragers were exposed to label dose variants of the fungicides iprodione, boscalid/pyraclostrobin formulation and azoxystrobin alone and in combination. Label dose variants of two insect growth regulators, methoxyfenozide and pyriproxyfen, as well as an acaricide, bifenazate, were also assessed for their effects on forager survival. We utilized a wind tunnel and atomizer set up (wind-speed: 2.9 m/s) to simulate field-relevant exposure of honey bees to these chemicals during aerial application in almond orchards. Our results indicate a significant decrease in forager survival resulting from exposure to pesticides commonly applied during almond bloom. To assess the effects of commonly used mosquito control insecticides on honey bee forager mortality, foragers were exposed using a wind tunnel-atomizer assembly simulating exposure from ultra-low volume spray truck application (wind-speed: 1.8 m/s). Significant acute forager mortality resulted from exposure to the mosquito control insecticides when applied above and below the manufacturer application rate

Exotic paired phases in ladders with spin-dependent hopping

Fermions in two-dimensions (2D) when subject to anisotropic spin-dependent hopping can potentially give rise to unusual paired states in {\it unpolarized} mixtures that can behave as non-Fermi liquids. One possibility is a fully paired state with a gap for fermion excitations in which the Cooper pairs remain uncondensed. Such a "Cooper-pair Bose-metal" phase would be expected to have a singular Bose-surface in momentum space. As demonstrated in the context of 2D bosons hopping with a frustrating ring-exchange interaction, an analogous Bose-metal phase has a set of quasi-1D descendent states when put on a ladder geometry. Here we present a density matrix renormalization group (DMRG) study of the attractive Hubbard model with spin-dependent hopping on a two-leg ladder geometry. In our setup, one spin species moves preferentially along the leg direction, while the other does so along the rung direction. We find compelling evidence for the existence of a novel Cooper-pair Bose-metal phase in a region of the phase diagram at intermediate coupling. We further explore the phase diagram of this model as a function of hopping anisotropy, density, and interaction strength, finding a conventional superfluid phase, as well as a phase of paired Cooper pairs with d-wave symmetry, similar to the one found in models of hard-core bosons with ring-exchange. We argue that simulating this model with cold Fermi gases on spin dependent optical lattices is a promising direction for realizing exotic quantum states.Comment: 10 pages, 12 figure

A mechanistic study of the EC′ mechanism – the split wave in cyclic voltammetry and square wave voltammetry

In this paper, a detailed investigation of electrochemical reactions coupled with homogenous chemical steps using cyclic voltammetry (CV) and square wave voltammetry (SWV) was carried out to study the electrocatalytic (EC’) mechanism. In CV, parameters including scan rate, electrode material and redox reactant were investigated while in SWV, parameters including substrate concentrations and frequencies were altered to demonstrate EC’ mechanism. Mechanistic studies focused on the EC’ mechanism using L-cysteine with ferrocenecarboxylic acid and 1,1 ′-ferrocenedicarboxylic acid respectively. Voltammetric responses were recorded and under conditions of high chemical rate constant and low substrate concentration, a split wave was observed in both CV and SWV studies

Younger adolescents’ perceptions of physical activity, exergaming, and virtual reality:qualitative intervention development study

Background. Novel strategies to promote physical activity (PA) in adolescence are required. The vEngage study aims to test whether a virtual reality (VR) exergaming intervention can engage younger adolescents (13-15 year old) with physical activity. Objective: This study aimed to gather adolescents’ views of using VR to encourage PA and identify the key features they would like to see in a VR exergaming intervention via interviews. Methods: Participants were recruited through two schools in London, UK. Semi-structured interviews were conducted with adolescents about their views on PA and what might work to increase PA, technology, knowledge and experience of VR, and desired features in a VR exergaming intervention. Data were analysed using Framework Analysis. Results: 31 13-15 year olds (58% female, 62% from non-white ethnicities) participated in this interview study. The vast majority had no awareness of government PA recommendations, but felt they should be more thoroughly informed. All participants were positive about the use of VR in PA promotion. Rewards, increasing challenges and a social/multiplayer aspect were identified by participants as crucial aspects to include in a VR exercise game. Barriers were related to cost of high-end systems. Being able to exercise at home was very appealing. VR exergaming was viewed as a way to overcome multiple perceived social and cultural barriers to PA, particularly for girls. Conclusions: Key elements that should be incorporated into a VR for health intervention were identified and described. These also included the use of rewards, novelty and enjoyment in immersive game play, multi-player options, real-world elements, as well as continual updates and new challenge levels. The use of VR to promote PA in adolescents is promising, but some barriers were raised