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"Frank, D"
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Detection of amitraz resistance and reduced treatment efficacy in the Varroa Mite, Varroa destructor, within commercial beekeeping operations
The parasitic mite Varroa destructor and the associated viruses it transmits are responsible for most instances of honey bee colony losses in the United States. As such, beekeepers utilize miticides to control Varroa populations. Widespread resistance has developed to the miticides fluvalinate and coumaphos. However, Varroa has largely maintained susceptibility to amitraz despite a long and extensive use history. Anecdotal reports of reduced amitraz effectiveness have been a widely discussed contemporary issue among commercial beekeepers. Amitraz resistance was measured by in vitro bioassays with technical amitraz as well as Apivar® efficacy tests. Amitraz resistance was evaluated in commercial beekeeping operations in Louisiana, New York, and South Dakota with a long history of amitraz use. This research shows that amitraz remains an effective Varroa control product in many operations. However, apiaries across operations displayed a wide range of amitraz resistance from no resistance to high resistance that resulted in Varroa control failure. The resistance ratios from in vitro amitraz bioassays were correlated with reduced Apivar® efficacy, demonstrating bona fide cases of Varroa control failures due to amitraz resistance. Therefore, amitraz resistance monitoring protocols need to be developed. A resistance monitoring network should be established to ensure the sustainability of miticide use for Varroa control.
Journal Article
Introduction to 3D game programming with DirectX 12
\"This updated bestseller provides an introduction to programming interactive computer graphics, with an emphasis on game development using DirectX 12. The book is divided into three main parts: basic mathematical tools, fundamental tasks in Direct3D, and techniques and special effects. It includes new Direct3D 12 features such as hardware tessellation and the compute shader, and covers advanced rendering techniques such as ambient occlusion, normal and displacement mapping, shadow rendering, particle systems, and character animation. Includes a companion DVD with code and figures.\"--Page 4 of cover.
Book
Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides
Chalcogen vacancies are generally considered to be the most common point defects in transition metal dichalcogenide (TMD) semiconductors because of their low formation energy in vacuum and their frequent observation in transmission electron microscopy studies. Consequently, unexpected optical, transport, and catalytic properties in 2D-TMDs have been attributed to in-gap states associated with chalcogen vacancies, even in the absence of direct experimental evidence. Here, we combine low-temperature non-contact atomic force microscopy, scanning tunneling microscopy and spectroscopy, and state-of-the-art ab initio density functional theory and GW calculations to determine both the atomic structure and electronic properties of an abundant chalcogen-site point defect common to MoSe
2
and WS
2
monolayers grown by molecular beam epitaxy and chemical vapor deposition, respectively. Surprisingly, we observe no in-gap states. Our results strongly suggest that the common chalcogen defects in the described 2D-TMD semiconductors, measured in vacuum environment after gentle annealing, are oxygen substitutional defects, rather than vacancies.
The nature of defects in transition metal dichalcogenide semiconductors is still under debate. Here, the authors determine the atomic structure and electronic properties of chalcogen-site point defects common to monolayer MoSe
2
and WS
2
, and find that these are substitutional defects, where a chalcogen atom is substituted by an oxygen atom, rather than vacancies.
Journal Article
Interacting bactofilins impact cell shape of the MreB-less multicellular Rhodomicrobium vannielii
Most non-spherical bacteria rely on the actin-like MreB cytoskeleton to control synthesis of a cell-shaping and primarily rod-like cell wall. Diverging from simple rod shape generally requires accessory cytoskeletal elements, which locally interfere with the MreB-guided cell wall synthesis. Conserved and widespread representatives of this accessory cytoskeleton are bactofilins that polymerize into static, non-polar bundles of filaments. Intriguingly, many species of the Actinobacteria and Rhizobiales manage to grow rod-like without MreB by tip extension, yet some of them still possess bactofilin genes, whose function in cell morphogenesis is unknown. An intricate representative of these tip-growing bacteria is Rhodomicrobium vannielii ; a member of the hitherto genetically not tractable and poorly studied Hyphomicrobiaceae within the MreB-less Rhizobiales order. R . vannielii displays complex asymmetric cell shapes and differentiation patterns including filamentous hyphae to produce offspring and to build dendritic multicellular arrays. Here, we introduce techniques to genetically access R . vannielii , and we elucidate the role of bactofilins in its sophisticated morphogenesis. By targeted mutagenesis and fluorescence microscopy, protein interaction studies and peptidoglycan incorporation analysis we show that the R . vannielii bactofilins are associated with the hyphal growth zones and that one of them is essential to form proper hyphae. Another paralog is suggested to represent a novel hybrid and co-polymerizing bactofilin. Notably, we present R . vannielii as a powerful new model to understand prokaryotic cell development and control of multipolar cell growth in the absence of the conserved cytoskeletal element, MreB.
Journal Article
Use of science to guide city planning policy and practice: how to achieve healthy and sustainable future cities
Land-use and transport policies contribute to worldwide epidemics of injuries and non-communicable diseases through traffic exposure, noise, air pollution, social isolation, low physical activity, and sedentary behaviours. Motorised transport is a major cause of the greenhouse gas emissions that are threatening human health. Urban and transport planning and urban design policies in many cities do not reflect the accumulating evidence that, if policies would take health effects into account, they could benefit a wide range of common health problems. Enhanced research translation to increase the influence of health research on urban and transport planning decisions could address many global health problems. This paper illustrates the potential for such change by presenting conceptual models and case studies of research translation applied to urban and transport planning and urban design. The primary recommendation of this paper is for cities to actively pursue compact and mixed-use urban designs that encourage a transport modal shift away from private motor vehicles towards walking, cycling, and public transport. This Series concludes by urging a systematic approach to city design to enhance health and sustainability through active transport and a move towards new urban mobility. Such an approach promises to be a powerful strategy for improvements in population health on a permanent basis.
Journal Article
The risk of indoor sports and culture events for the transmission of COVID-19
Nearly all mass gathering events worldwide were banned at the beginning of the COVID-19 pandemic, as they were suspected of presenting a considerable risk for the transmission of SARS-CoV-2. We investigated the risk of transmitting SARS-CoV-2 by droplets and aerosols during an experimental indoor mass gathering event under three different hygiene practices, and used the data in a simulation study to estimate the resulting burden of disease under conditions of controlled epidemics. Our results show that the mean number of measured direct contacts per visitor was nine persons and this can be reduced substantially by appropriate hygiene practices. A comparison of two versions of ventilation with different air exchange rates and different airflows found that the system which performed worst allowed a ten-fold increase in the number of individuals exposed to infectious aerosols. The overall burden of infections resulting from indoor mass gatherings depends largely on the quality of the ventilation system and the hygiene practices. Presuming an effective ventilation system, indoor mass gathering events with suitable hygiene practices have a very small, if any, effect on epidemic spread.
Mass gathering events represent a risk for transmission of SARS-CoV-2. Here, the authors describe an experimental indoor test event in which individual contacts were measured and use aerosol and epidemiological modelling to evaluate transmission risks of different types of restrictions in the arena.
Journal Article