A global inventory of photovoltaic solar energy generating units.

Photovoltaic (PV) solar energy generating capacity has grown by 41 per cent per year since 20091. Energy system projections that mitigate climate change and aid universal energy access show a nearly ten-fold increase in PV solar energy generating capacity by 20402,3. Geospatial data describing the energy system are required to manage generation intermittency, mitigate climate change risks, and identify trade-offs with biodiversity, conservation and land protection priorities caused by the land-use and land-cover change necessary for PV deployment. Currently available inventories of solar generating capacity cannot fully address these needs1-9. Here we provide a global inventory of commercial-, industrial- and utility-scale PV installations (that is, PV generating stations in excess of 10 kilowatts nameplate capacity) by using a longitudinal corpus of remote sensing imagery, machine learning and a large cloud computation infrastructure. We locate and verify 68,661 facilities, an increase of 432 per cent (in number of facilities) on previously available asset-level data. With the help of a hand-labelled test set, we estimate global installed generating capacity to be 423 gigawatts (-75/+77 gigawatts) at the end of 2018. Enrichment of our dataset with estimates of facility installation date, historic land-cover classification and proximity to vulnerable areas allows us to show that most of the PV solar energy facilities are sited on cropland, followed by aridlands and grassland. Our inventory could aid PV delivery aligned with the Sustainable Development Goals.

Reproductive isolation between divergent races of pea aphids on two hosts. II. Selection against migrants and hybrids in the parental environments.

Sympatric races of pea aphids on alfalfa and red clover are highly ecologically specialized and significantly reproductively isolated. Much of the restriction of gene flow between the specialized populations is due to habitat choice behavior of the winged colonizers (Via 1999). Here, we document additional pre- and postmating reproductive isolation through selection against migrants and hybrids in the parental environments. First, a group of randomly chosen genotypes from each race that were experimentally migrated between hosts had very low survival and reproduction on the alternate host relative to genotypes originating from that host (natives). Such selection against cross-host migrants forms a premating barrier to gene flow because it is likely to reduce migrant frequencies before the sexual forms are induced in the fall. Our reciprocal transplant experiment also shows that natural selection acts directly on individual migrants between the crops to favor host choice behavior: genotypes from each host suffered large losses of fitness when forced to migrate to the alternate host plant relative to the fitness they would have enjoyed had they been able to choose their native host. In a companion field study, sequential sampling throughout the summer in newly colonized fields of both alfalfa and clover revealed a decrease in the frequency of host-specific marker alleles characteristic of the alternate crop. These field data further support the hypothesis that selection disfavors migrants that cross between crops. Second, when two sets of F1 hybrids between the races were reciprocally tested on alfalfa and clover, both sets had significantly lower average fitness than the specialized parent in each of the two environments. This demographic selection against hybrids in the parental environments is a source of postmating reproductive isolation between the specialized races. Finally, significant genetic variation in fitness traits was seen among F1 hybrid genotypes from both crosses between alfalfa and clover specialists. Although this variation suggests that a generalized pea aphid could evolve, such generalists are not seen in field collections of these populations.

Risk adjusting capitation: applications in employed and disabled populations.

Risk adjustment may be a sensible strategy to reduce selection bias because it links managed care payment directly to the costs of providing services. In this paper we compare risk adjustment models in two populations (public employees and their dependents, and publicly-insured low income individuals with disabilities) in Washington State using two statistical approaches and three health status measures. We conclude that a two-part logistic/GLM statistical model performs better in populations with large numbers of individuals who do not use health services. This model was successfully implemented in the employed population, but the managed care program for the publicly insured population was terminated before risk adjustment could be applied. The choice of the most appropriate health status measure depends on purchasers' principles and desired outcomes.

State-sponsored programs for the uninsured: is there adverse selection?

Risk contracting by states for coverage of previously uninsured populations has been hampered by uncertainty regarding likely claims experience. This study reports on the utilization experience of two state programs offering subsidized coverage in commercial managed care organizations to low-income and previously uninsured people. Program participants used services similarly to people enrolled through large employer benefit plans. There was no evidence of pent-up demand or an unusual level of chronic illness. Similarly, there was little evidence of underutilization, although dissatisfaction and reported barriers to service were more frequent among nonwhite enrollees.

Health care utilization for the "newly insured": results from the Washington Basic Health Plan.

The risk of providing coverage for low-income people formerly without insurance is unknown. We conducted an evaluation to describe the use of services from 1989-1992 for members of the Basic Health Plan (BHP), a subsidized health insurance program for low-income individuals in the state of Washington. There was evidence of pent-up demand for care for those who had been without insurance for more than a year. Overall, members in the BHP program were not high users of care, although one of the three plans we examined had significantly higher utilization than the other two. BHP total expenditures were comparable to those for state employees and lower than those for Medicaid recipients.

Will uninsured people volunteer for voluntary health insurance? Experience from Washington State.

OBJECTIVES: In national and local discussions of health care reform, there is disagreement about whether a national health insurance plan should be mandatory or voluntary. This study describes characteristics of low- income people who were more likely or less likely to be covered by a voluntary plan. METHODS: Survey data were available from an evaluation of Washington State's Basic Health Plan, which offered subsidized health insurance to low-income residents. For those subjects who were eligible and uninsured at baseline, those who joined were compared with those who did not join on a variety of demographic and health-related characteristics. RESULTS: There were substantial differences between those who did and did not join the Basic Health Plan. Those who did not enroll were generally less well-off, with less education, lower income, and worse health. Many had never had health insurance. CONCLUSIONS: If health care reform results in a voluntary plan, additional measures may be needed to ensure that less advantaged citizens have adequate access to health care.

Voluntary public health insurance for low-income families: the decision to enroll.

A dominant issue in the health reform debate is whether insurance coverage should be voluntary or mandatory. Clearly, the factors that determine who will seek voluntary coverage are relevant to this policy issue. This article uses experience from Washington State's Basic Health Plan to examine the enrollment choices of low-income families in a state-subsidized voluntary insurance plan offered through managed care organizations. We hypothesize that the decision to enroll, which encompasses the decisions to purchase insurance coverage and to select a particular plan, is influenced by four factors: the family's financial vulnerability, their risk perception, the price of coverage, and the transition costs of enrolling. Our enrollment model is supported by the data and has important implications for the design of voluntary programs. Families who choose to enroll are more likely to have a female head of household, young children, and a family member who has a part-time job and some college education. Higher premiums and availability of other insurance coverage decrease the probability of enrolling.

Who enrolled in a state program for the uninsured: was there adverse selection?

Managed care plans may hesitate to participate in programs for uninsured persons because they fear adverse selection, whereby only the sickest people or highest users would choose to join the program. We studied this issue in Washington State's Basic Health Plan, a demonstration program that provides subsidized health insurance for families earning less than 200% of the poverty level. We interviewed people in three counties who enrolled in the program, and compared them to people in the same counties who were eligible but did not enroll. There were substantial differences between enrollees and eligibles in education, age, income, employment, race, and insurance status. In spite of these demographic and access differences, health status was remarkably similar for enrollees and eligibles, with the few significant differences favoring the enrollees. In addition, previous and subsequent use of health services was similar or lower for enrollees. The results for health status and utilization were similar across the three counties, even though the counties and the providers were quite different. We conclude that there is no evidence of adverse selection. This is welcome news for the health plans, but suggests that the BHP may not have reached those most in need of insurance.

Estimating county percentages of people without health insurance.

County data on the percentage of people without health insurance are seldom available, although state program planning requires such information. As part of an evaluation of Washington's Basic Health Plan (BHP), we conducted a telephone survey in nine Washington counties to estimate the percentage of people under the age of 65 who were uninsured. We used regression analysis to estimate the percentage uninsured in a county as a function of the percentage unemployed. Two validation approaches yielded very good results, suggesting that the equation could be used to estimate the percentage uninsured in unsurveyed counties. The variation ranged from 15% to 23% uninsured in the 9 surveyed counties, and was estimated to range from 9% to 35% among the state's 39 counties. With proper caution, estimates based on this equation can probably be used in other states if better data are unavailable.