Chemical vapour deposition synthetic diamond: materials, technology and applications

Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form, however non-planar geometries are also possible and enable a number of key applications. This article reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, based on the ability to synthesize a consistent and engineered high performance product.Comment: 51 pages, 16 figure

Axonal Regeneration and Neuronal Function Are Preserved in Motor Neurons Lacking ß-Actin In Vivo

The proper localization of ß-actin mRNA and protein is essential for growth cone guidance and axon elongation in cultured neurons. In addition, decreased levels of ß-actin mRNA and protein have been identified in the growth cones of motor neurons cultured from a mouse model of Spinal Muscular Atrophy (SMA), suggesting that ß-actin loss-of-function at growth cones or pre-synaptic nerve terminals could contribute to the pathogenesis of this disease. However, the role of ß-actin in motor neurons in vivo and its potential relevance to disease has yet to be examined. We therefore generated motor neuron specific ß-actin knock-out mice (Actb-MNsKO) to investigate the function of ß-actin in motor neurons in vivo. Surprisingly, ß-actin was not required for motor neuron viability or neuromuscular junction maintenance. Skeletal muscle from Actb-MNsKO mice showed no histological indication of denervation and did not significantly differ from controls in several measurements of physiologic function. Finally, motor axon regeneration was unimpaired in Actb-MNsKO mice, suggesting that ß-actin is not required for motor neuron function or regeneration in vivo

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Territory, River, and Maritime Claims in the Western Hemisphere: Regime Type, Rivalry, and MIDs from 1901 to 2000

Issues remain at the core of armed conflict. Territory, in particular, appears to increase substantially the probability of inter-state violence and is concluded by many to be one of the most critical correlates of war onset. While scholars have called for an issue-based approach to the study of international relations for some time, recent data collection efforts allow the emergence and management of contentious issues over time to be studied more directly. Our argument and evidence suggest that territory is not necessarily contentious by itself, but is contentious in dyadic contexts characterized by rivalry. Using data from the Issue Correlates of War project, which codes specific government assertions of ownership to territory, river, and maritime locations, we find strategic rivalry, coupled with territorial claims, produces some of the most conflict-prone dyads. Further, jointly democratic domestic institutions do not appear to reduce the hazard of violent conflict over territorial issues within the context of rivalry, although they substantially reduce the hazard of violent conflict among states outside the context of rivalry

Opportunities and Presidential Uses of Force

Political vulnerability is thought to influence the opportunities available to the US president to engage in uses of force abroad. Conventional theories linking economic misfortune and partisan opposition to presidential uses of force detail the incentives and constraints facing the president in decisions to use force. In contrast, these theories’ strategic counterparts focus on the ability of US adversaries to respond to the president’s vulnerability through either avoidance or exploitation. The behavior of US adversaries is thought to critically affect the president’s opportunities to use force. Conventional and strategic accounts of the linkage between domestic political vulnerability and the use of force provide contradictory expectations. To assess these theories we identify hypotheses related to four dependent and selection variables corresponding to dispute initiation and reciprocation involving the US. These hypotheses are tested with a two-stage Heckman Probit model to account for selection effects due to strategic interaction. The results are most supportive of orthodox diversionary theory. Our findings challenge the other perspectives evaluated—the strategic conflict avoidance (SCA) perspective, Howell and Pevehouse’s party cover approach, and Schultz’s signaling model.congressional-executive relations; diversionary theory; partisan cover theory; presidential use of force; signaling theory; strategic conflict avoidance; war powers

Enforcing order: Territorial reach and maritime piracy

Existing studies of piracy focus attention on the institutional determinants of maritime piracy, but neglect variation in governments’ reach over territory. We argue that the effect of state capacity on piracy is a function of states’ ability to extend authority over the country’s entire territory. We expect that government reach—a function of geographic factors such as the distance between a country’s capital and its coastline—mediates the effect of state capacity on piracy. Weak governments allow for the planning and implementation of attacks and reduce the risk of capture, but particularly so if sufficient distance separates pirates from political authority. An empirical analysis of country-year data on maritime piracy collected by the International Maritime Bureau for the 1995-2013 period shows that capital-coastline distance mediates the effect of institutional fragility on piracy as hypothesized. These results remain robust for alternative operationalizations of state capacity and reach. In addition, the models perform well in terms of predictive power, forecasting piracy quite accurately for 2013. The expectations and evidence presented in this paper help explain why states with intermediate levels of state capacity but low levels of reach—such as Indonesia, Tanzania or Venezuela—struggle with substantial incidence of piracy

Generational effects of culture and digital media in former Soviet Republics

Abstract In public opinion, social and digital media provide means for influence as well as sorting according to pre-existing values. Here we consider types of media usage versus opinion using new polling results in the former Soviet republics (FSRs) of Belarus, Ukraine, and Georgia. Over 1000 individuals in each country were asked about a news event (the January 6 riot at the U.S. Capitol) and about the long-term future of their country. We find that year of birth and country of residence, rather than self-reported media reliance, consistently predicted the respondents’ views, particularly on the future of their country. The timing of these differences suggests a cultural difference between generations growing up in the Soviet Union (likely more pro-Russian) versus afterward, in an FSR (more pro-Western). Whereas digital media choice is somewhat correlated with perceptions of a recent, international news event, the more predictive factors are longer-term cultural values and age cohorts within each nation