Numerical and Experimental Study on the Addition of Surface Roughness to Micro-Propellers

Micro aerial vehicles are making a large impact in applications such as search-and-rescue, package delivery, and recreation. Unfortunately, these diminutive drones are currently constrained to carrying small payloads, in large part because they use propellers optimized for larger aircraft and inviscid flow regimes. Fully realizing the potential of emerging microflyers requires next-generation propellers that are specifically designed for low-Reynolds number conditions and that include new features advantageous in highly viscous flows. One aspect that has received limited attention in the literature is the addition of roughness to propeller blades as a method of reducing drag and increasing thrust. To investigate this possibility, we used large eddy simulation to conduct a numerical investigation of smooth and rough propellers. Our results indicate that roughness produces a 2% increase in thrust and a 5% decrease in power relative to a baseline smooth propeller operating at the same Reynolds number of Rec = 6500, held constant by rotational speed. We corroborated our numerical findings using thrust-stand-based experiments of 3D-printed propellers identical to those of the numerical simulations. Our study confirms that surface roughness is an additional parameter within the design space for micro-propellers that will lead to unprecedented drone efficiencies and payloads.Comment: 23 Pages, 9 Figure

“It doesn’t mean I’m useless” How do young people experiencing psychosis contribute to their families and why are their contributions sometimes overlooked?

Purpose: Psychosis is often seen as a “burden” on families. and affected individuals frequently hold a negative view of themselves. This study explored the ways in which young adults who have experienced first episode psychosis (FEP) make a positive contribution within their families. Methods: Fifteen participants (seven young people with experience of psychosis and eight relatives) were interviewed separately. Their accounts were analysed using grounded theory methodology (Charmaz, 2006). Results: For many individuals, their experience had led to a catastrophic redefinition of their identity. However, they continued to contribute significantly both within their families and within their wider communities. The redefinition of identity sometimes appeared to create a ‘perceptual filter’ whereby both the person themselves and family members overlooked or minimised their contribution, focusing instead on being alert to signs of psychosis or illness. Conclusions: Shame and a focus on symptoms rather than achievements and contributions can significantly limit opportunities, expectations, and movement beyond an illness identity. It is important for clinicians to be aware of this and to help young people and their families to notice and value positive contribution, and so promote recovery, well-being and post-traumatic growth

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

Defining adult bonefish (Albula vulpes) movement corridors around Grand Bahama in the Bahamian Archipelago

Abstract Development on Grand Bahama in the Bahamian Archipelago during the 1950's to 1970's resulted in substantial changes to the island's geography. Hawksbill Creek, which potentially served as a natural migration route for fish from the north side to the south side of the island, was severed and replaced by a man-made canal called the Grand Lucayan Waterway (GLW). Bonefish (Albula spp.), a sport-fish that contributes more than $141 million to the Bahamian economy annually, is one such species that may have been affected. The purpose of this study was to determine contemporary movement corridors of adult bonefish during their spawning season (October to May) in Grand Bahamian waters. This was accomplished by using a passive acoustic telemetry array of 17 receivers and 30 transmitter-implanted individuals. A total of 26,108 detections were logged from 20 of the fish. Eight bonefish tagged on the north side used the GLW to access waters on the south, whereas no transmitter-implanted fish tagged on the south side fully traversed the man-made canal, suggesting that primary spawning areas may be located on the south side of the island. This result is consistent with previous reports that bonefish spawn near deep water which is easier to access on the south side of Grand Bahama. Further supporting this finding, two other bonefish tagged on the north side forayed around the east end of the island and were detected on receivers approximately 88 km from their tagging locations. Additionally, two other bonefish tagged on the north side were detected at the west end of the island, with one individual continuing its movements along the south side of the island for an approximate straight-line distance of 80 km. Canal use typically corresponded to days immediately prior to or after new or full moons, indicating that movements were related to spawning. This study suggests that despite historical habitat modifications, bonefish today use the GLW as a movement corridor for migrations during spawning season, emphasizing the importance of protecting the canal from any activities that could impede connectivity

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

Elite Suppressor–Derived HIV-1 Envelope Glycoproteins Exhibit Reduced Entry Efficiency and Kinetics

Elite suppressors (ES) are a rare subset of HIV-1–infected individuals who are able to maintain HIV-1 viral loads below the limit of detection by ultra-sensitive clinical assays in the absence of antiretroviral therapy. Mechanism(s) responsible for this elite control are poorly understood but likely involve both host and viral factors. This study assesses ES plasma-derived envelope glycoprotein (env) fitness as a function of entry efficiency as a possible contributor to viral suppression. Fitness of virus entry was first evaluated using a novel inducible cell line with controlled surface expression levels of CD4 (receptor) and CCR5 (co-receptor). In the context of physiologic CCR5 and CD4 surface densities, ES envs exhibited significantly decreased entry efficiency relative to chronically infected viremic progressors. ES envs also demonstrated slow entry kinetics indicating the presence of virus with reduced entry fitness. Overall, ES env clones were less efficient at mediating entry than chronic progressor envs. Interestingly, acute infection envs exhibited an intermediate phenotypic pattern not distinctly different from ES or chronic progressor envs. These results imply that lower env fitness may be established early and may directly contribute to viral suppression in ES individuals

Madagascar’s extraordinary biodiversity: Threats and opportunities

Madagascar's unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar's terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as themost prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar

Madagascar’s extraordinary biodiversity: Evolution, distribution, and use

Madagascar's biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar's past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique living laboratory for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth's biodiversity