Hard X-ray and low-energy gamma-ray spectrometers

Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resolution for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.     

Assessing climate change impacts on California hydropower generation and ancillary services provision

Climate change is already affecting species and their distributions. Distributional range changes have occurred and are projected to intensify for many widespread plants and animals, creating associated risks to many ecosystems. Here, we estimate the climate change-related risks to the species in globally significant biodiversity conservation areas over a range of climate scenarios, assessing their value as climate refugia. In particular, we quantify the aggregated benefit of countries’ emission reduction pledges (Intended Nationally Determined Contributions and Nationally Determined Contributions under the Paris Agreement), and also of further constraining global warming to 2 °C above pre-industrial levels, against an unmitigated scenario of 4.5 °C warming. We also quantify the contribution that can be made by using smart spatial conservation planning to facilitate some levels of autonomous (i.e. natural) adaptation to climate change by dispersal. We find that without mitigation, on average 33% of each conservation area can act as climate refugium (or 18% if species are unable to disperse), whereas if warming is constrained to 2 °C, the average area of climate refuges doubles to 67% of each conservation area (or, without dispersal, more than doubles to 56% of each area). If the country pledges are fulfilled, an intermediate estimate of 47–52% (or 31–38%, without dispersal) is obtained. We conclude that the Nationally Determined Contributions alone have important but limited benefits for biodiversity conservation, with larger benefits accruing if warming is constrained to 2 °C. Greater benefits would result if warming was constrained to well below 2 °C as set out in the Paris Agreement.     

Organization‐Led Migration,Individual Choice,and Refugee Resettlement in The U.S.: Seeking Regularities

The role of organizations in migration has received less attention than warranted; individual choice has typically been emphasized. As an in‐depth illustration, we consider refugee resettlement in the United States, post–World War II, wherein intermediary organizations play(ed) a major role. Central to this system are voluntary agencies (VOLAGs) and community organizations, but secondary migration also is critical. Attention is given to all refugees between 2000 and 2010, and in greater detail to Somalis. The latter provides deeper understanding through state refugee coordinators and case studies of Columbus, Ohio, Minneapolis, Minnesota, and Lewiston, Maine. Aside from process, it is evident that the geography of the foreign‐born settlement has been altered. While refugee resettlement and subsequent migration is the example, we broaden that to argue that migration studies have neglected the derived nature of movement via intermediary organizations; directed migrations and/or similar interventions have played a significant, if not dominant, role in population redistribution; and organization‐led migration should be considered in terms of general aspects, not simply as discrete case studies.