Effects of publication bias on conservation planning

Conservation planning needs reliable information on spatial patterns of biodiversity. However, existing data sets are skewed: some habitats, taxa, and locations are under-represented. Here, we map geographic publication density at the sub-national scale of individual 'provinces'. We query the Web of Science catalogues SCI and SSCI for biodiversity-related publications including country and province names (for the period 1993-2016). We combine these data with other provincial-scale factors hypothesised to affect research (i.e. economic development, human presence, infrastructure and remoteness). We show that sites that appear to be understudied, compared with the biodiversity expected from their bioclimatic conditions, are likely to have been inaccessible to researchers for a diversity of reasons amongst which current or recent armed conflicts are notable. Finally, we create a priority list of provinces where geographic publication bias is of most concern, and discuss how our provincial-scale model can assist in adjusting for publication biases in conservation planning.Comment: 10 pages; 3 figures; 1 table;R code on https://github.com/raffael-hickisch; data at https://zenodo.org/record/998889; interactive at http://bit.ly/publication_density_ma

Recent progress in the CoCrNi alloy system

The exceptional mechanical properties, particularly at cryogenic temperatures, of the equiatomic CoCrNi alloy are documented in numerous published studies. Similar to the equiatomic CoCrFeMnNi (so called Cantor alloy), from which the ternary alloy was derived, the CoCrNi ternary possesses low stacking fault energy that promotes complex deformation modes, as well as the activation of deformation twinning at ambient temperatures and increased strain. In addition to outstanding deformation mechanisms, chemical short-range order and face-centered cubic (FCC)-hexagonal close packed (HCP) transitions have been verified in this alloy and prove to be key factors contributing to the alloy\u27s notable properties. The relationship between stacking fault energy and FCC→HCP phase transitions has been developed over the years through other low stacking fault materials, but the question that arises is: do well established physical metallurgical mechanisms require modification when applied to systems such as CoCrNi given their compositional complexity? Local chemical order plays an important role in that it brings the deviation from the random solid solution behavior generally expected from complex concentrated alloys. In this review, the fundamental atomistic deformation mechanisms of the CoCrNi alloy will be reviewed with a focus on deformation substructures and chemical short-range ordering. Recent studies on microstructural engineering through thermo-mechanical processing and efforts to enhance the tensile properties of the CoCrNi derived systems with minor alloying additions are discussed. Finally, future directions of research, which involve applying current understanding of the underlying mechanisms towards alloy design strategies, are discussed

Two-Stage Passive Vibration Isolator

The design and testing of a structural system were implemented to hold the optics of the planned Space Interferometry Mission (SIM) at positions and orientations characterized by vibrational translation and rotation errors of no more than a few nanometers or a few milliarcseconds, respectively. Much of the effort was devoted to a test bed for verifying the predicted behavior of a vibration- isolation structural subsystem working together with an active control system for positioning and orienting the SIM optics. There was considerable emphasis on the vibration-isolation subsystem, which was passive and comprised two stages. The main sources of vibration were six reaction wheels in an assembly denoted the "backpack." The first vibration-isolation stage consisted of hexapod isolator mounts - one for each reaction wheel - characterized by a natural vibration frequency of 10 Hz. The second stage was a set of three beams, disposed between the backpack and the structure that held the SIM optics, that were flexured such that they transmitted only bending loads, with a natural vibrational frequency and damping of about 5 Hz and 4 percent, respectively. Preliminary test results were presented and characterized as demonstrating the effectiveness of the two-stage vibration-isolation design

Functional Characterization of a Novel Family of Acetylcholine-Gated Chloride Channels in Schistosoma mansoni

Acetylcholine is the canonical excitatory neurotransmitter of the mammalian neuromuscular system. However, in the trematode parasite Schistosoma mansoni, cholinergic stimulation leads to muscle relaxation and a flaccid paralysis, suggesting an inhibitory mode of action. Information about the pharmacological mechanism of this inhibition is lacking. Here, we used a combination of techniques to assess the role of cholinergic receptors in schistosome motor function. The neuromuscular effects of acetylcholine are typically mediated by gated cation channels of the nicotinic receptor (nAChR) family. Bioinformatics analyses identified numerous nAChR subunits in the S. mansoni genome but, interestingly, nearly half of these subunits carried a motif normally associated with chloride-selectivity. These putative schistosome acetylcholine-gated chloride channels (SmACCs) are evolutionarily divergent from those of nematodes and form a unique clade within the larger family of nAChRs. Pharmacological and RNA interference (RNAi) behavioral screens were used to assess the role of the SmACCs in larval motor function. Treatment with antagonists produced the same effect as RNAi suppression of SmACCs; both led to a hypermotile phenotype consistent with abrogation of an inhibitory neuromuscular mediator. Antibodies were then generated against two of the SmACCs for use in immunolocalization studies. SmACC-1 and SmACC-2 localize to regions of the peripheral nervous system that innervate the body wall muscles, yet neither appears to be expressed directly on the musculature. One gene, SmACC-1, was expressed in HEK-293 cells and characterized using an iodide flux assay. The results indicate that SmACC-1 formed a functional homomeric chloride channel and was activated selectively by a panel of cholinergic agonists. The results described in this study identify a novel clade of nicotinic chloride channels that act as inhibitory modulators of schistosome neuromuscular function. Additionally, the iodide flux assay used to characterize SmACC-1 represents a new high-throughput tool for drug screening against these unique parasite ion channels

Topologically Protected Helical States in Minimally Twisted Bilayer Graphene

In minimally twisted bilayer graphene, a moir{\'e} pattern consisting of AB and BA stacking regions separated by domain walls forms. These domain walls are predicted to support counterpropogating topologically protected helical (TPH) edge states when the AB and BA regions are gapped. We fabricate designer moir{\'e} crystals with wavelengths longer than 50 nm and demonstrate the emergence of TPH states on the domain wall network by scanning tunneling spectroscopy measurements. We observe a double-line profile of the TPH states on the domain walls, only occurring when the AB and BA regions are gapped. Our results demonstrate a practical and flexible method for TPH state network construction.Comment: 12 pages, 4 figure

Potential Cislunar and Interplanetary Proving Ground Excursion Trajectory Concepts

NASA has been investigating potential translunar excursion concepts to take place in the 2020s that would be used to test and demonstrate long duration life support and other systems needed for eventual Mars missions in the 2030s. These potential trajectory concepts could be conducted in the proving ground, a region of cislunar and near-Earth interplanetary space where international space agencies could cooperate to develop the technologies needed for interplanetary spaceflight. Enabled by high power Solar Electric Propulsion (SEP) technologies, the excursion trajectory concepts studied are grouped into three classes of increasing distance from the Earth and increasing technical difficulty: the first class of excursion trajectory concepts would represent a 90-120 day round trip trajectory with abort to Earth options throughout the entire length, the second class would be a 180-210 day round trip trajectory with periods in which aborts would not be available, and the third would be a 300-400 day round trip trajectory without aborts for most of the length of the trip. This paper provides a top-level summary of the trajectory and mission design of representative example missions of these three classes of excursion trajectory concepts