Theory, Data, and Deterrence: A Response to Kenwick, Vasquez, and Powers

Kenwick, Vasquez, and Powers question whether empirical evidence supports the claim that defense pacts deter conflict as our prior research has concluded. We review the theoretical argument for why defense pacts should deter conflict and consider the challenges inherent in evaluating deterrence using observational data. We then consider whether the research design choices of Kenwick et al. improve upon our research design. We demonstrate that claims that defense pacts deter conflict are robust to many of these changes in research design, and we argue that the consequential difference, while perhaps appropriate for testing the Steps-to-War argument, is not appropriate for testing the deterrent effect of defense pacts. We conclude by noting that a deterrence effect of defense pacts is not necessarily incompatible with aspects of the Steps-to-War argument, and we suggest profitable new directions for testing the Steps-to-War approach

Silicon Carbide for Novel Quantum Technology Devices

Silicon carbide (SiC) has recently been investigated as an alternative material to host deep optically active defects suitable for optical and spin quantum bits. This material presents a unique opportunity to realise more advanced quantum-based devices and sensors than currently possible. We will summarise key results revealing the role that defects have played in enabling optical and spin quantum measurements in this material such as single photon emission and optical spin control. The great advantage of SiC lies in its existing and well-developed device processing protocols and the possibilities to integrate these defects in a straightforward manner. There is particular current interest in nanomaterials and nanophotonics in SiC that could, once realised, introduce a new platform for quantum nanophotonics and in general for photonics. We will summarise SiC nanostructures exhibiting optical emission due to multiple polytypic bandgap engineering and deep defects. The combination of nanostructures and in-built paramagnetic defects in SiC could pave the way for future single-particle and single-defect quantum devices and related biomedical sensors with single-molecule sensitivity. We will review relevant classical devices in SiC (photonics crystal cavities, microdiscs) integrated with intrinsic defects. Finally, we will provide an outlook on future sensors that could arise from the integration of paramagnetic defects in SiC nanostructures and devices

Careful Commitments: Democratic States and Alliance Design

Evidence suggests that leaders of democratic states experience high costs from violating past commitments. We argue that because democratic leaders foresee the costs of violation, they are careful to design agreements they expect to have a high probability of fulfilling. This may cause democratic leaders to prefer flexible or limited commitments. We evaluate our argument by analyzing the design of alliance treaties signed by countries of the world between 1815 and 2003. We find that alliances formed among democratic states are more likely to include obligations for future consultation rather than precommitting leaders to active conflict, and defense pacts formed among democratic states are more likely to specify limits to the conditions under which member states must join their partners in conflict. This research suggests that separating screening effects and constraining effects of international agreements is even more difficult than previously believed. States with the greatest likelihood of being constrained are more carefully screened

What Do Students Experience as Peer Leaders of Learning Teams?

In a course for engineering freshmen, peer leaders facilitated optional study sessions, which implemented peer-led team learning workshops. Some leaders were paid teaching assistants, but most were undergraduate volunteers. To understand the experiences of the peer leaders, we asked them to keep weekly reflective journals. By performing a basic qualitative analysis of fourteen journals from two semesters, we developed a description of the experience of leading peer-led team learning workshops over the course of the semester. At the beginning of the semester, the leaders were apprehensive about teaching and concerned with correctly answering students’ questions. As the semester progressed, the leaders were often frustrated with the difficulty of teaching, and the leaders tried new ways of encouraging student participation. At the end of the semester, the leaders reported that they increased self-confidence, developed an appreciation for intellectual diversity, and gained an increased interest in teaching

Tracing the Origins and Evolution of Small Planets using Their Orbital Obliquities

We recommend an intensive effort to survey and understand the obliquity distribution of small close-in extrasolar planets over the coming decade. The orbital obliquities of exoplanets--i.e., the relative orientation between the planetary orbit and the stellar rotation--is a key tracer of how planets form and migrate. While the orbital obliquities of smaller planets are poorly explored today, a new generation of facilities coming online over the next decade will make such observations possible en masse. Transit spectroscopic observations with the extremely large telescopes will enable us to measure the orbital obliquities of planets as small as $\sim2R_{\oplus}$ around a wide variety of stars, opening a window into the orbital properties of the most common types of planets. This effort will directly contribute to understanding the formation and evolution of planetary systems, a key objective of the National Academy of Sciences' Exoplanet Science Strategies report.Comment: Submitted to the Astro2020 call for science white papers. 7 pages, 2 figure

Antimony uptake and toxicity in sunflower and maize growing in SbIII and SbV contaminated soil

Using pot experiments, we investigated the uptake of antimony (Sb) by sunflower (Helianthus annuus L. cv. Iregi), and maize (Zea mays L. cv. Magister) in two different soils, a potting mix and an agricultural soil. In one treatment Sb was added to the experimental soils as KSb(OH)6 ("SbV-treatment”) and in the other as Sb2O3 ("SbIII-treatment”). Soluble soil Sb concentrations were linearly related to the applied Sb rates, ranging from 0.02 (controls) to 175mgL−1 soil solution. Accumulation of Sb tended to be slightly higher in the SbV treatment in sunflower, while no difference in Sb uptake between the two Sb treatments was found in maize. The half maximal effective concentration (EC50) values derived from the dose-response curves were higher for the SbV than for the SbIII treatment when they were related to soluble soil Sb concentrations, but differences became insignificant when they were related to shoot Sb concentrations. Maize was substantially more sensitive to Sb toxicity than sunflower, indicating physiological differences in Sb tolerance between the two plant species. Our results show that on soils with high Sb contamination, as often found in shooting ranges, plants may suffer from Sb toxicit