Recent advancements in monolithic AlGaAs/GaAs solar cells for space applications

High efficiency, two terminal, multijunction AlGaAs/GaAs solar cells were reproducibly made with areas of 0.5 sq cm. The multiple layers in the cells were grown by Organo Metallic Vapor Phase Epitaxy (OMVPE) on GaAs substrates in the n-p configuration. The upper AlGaAs cell has a bandgap of 1.93 eV and is connected in series to the lower GaAs cell (1.4 eV) via a metal interconnect deposited during post-growth processing. A prismatic coverglass is installed on top of the cell to reduce obscuration caused by the gridlines. The best 0.5 sq cm cell has a two terminal efficiency of 23.0 pct. at 1 sun, air mass zero (AM0) and 25 C. To date, over 300 of these cells were grown and processed for a manufacturing demonstration. Yield and efficiency data for this demonstration are presented. As a first step toward the goal of a 30 pct. efficient cell, a mechanical stack of the 0.5 sq cm cells described above, and InGaAsP (0.95 eV) solar cells was made. The best two terminal measurement to date yields an efficiency of 25.2 pct. AM0. This is the highest reported efficiency of any two terminal, 1 sun space solar cell

Drivers of taxonomic bias in conservation research : a global analysis of terrestrial mammals

Scientific knowledge of species and the ecosystems they inhabit is the cornerstone of modern conservation. However, research effort is not spread evenly among taxa (taxonomic bias), which may constrain capacity to identify conservation risk and to implement effective responses. Addressing such biases requires an understanding of factors that promote or constrain the use of a particular species in research projects. To this end, we quantified conservation science knowledge of the world's extant non-marine mammal species (n = 4108) based on the number of published documents in journals indexed on Clarivate Analytics' Web of Science (TM). We use an innovative hurdle model approach to assess the relative importance of several ecological, biogeographical and cultural factors for explaining variation in research production between species. The most important variable explaining the presence/absence of conservation research was scientific capacity of countries within the range of the species, followed by body mass and years since the taxonomic description. Research volume (more than one document) was strongly associated with number of years since the data describing on that species, followed by scientific capacity within the range of species, high body mass and invasiveness. The threat status was weakly associated to explain the presence/absence and research volume in conservation research. These results can be interpreted as a consequence of the dynamic interplay between the perceived need for conservation research about a species and its appropriateness as a target of research. As anticipated, the scientific capacity of the countries where a species is found is a strong driver of conservation research bias, reflecting the high variation in conservation research funding and human resources between countries. Our study suggests that this bias could be most effectively reduced by a combination of investing in pioneering research, targeted funding and supporting research in countries with low scientific capacity and high biodiversity.Peer reviewe

The 25 percent-efficient GaAs Cassegrainian concentrator cell

Very high-efficiency GaAs Cassegrainian solar cells have been fabricated in both the n-p and p-n configurations. The n-p configuration exhibits the highest efficiency at concentration, the best cells having an efficiency eta of 24.5 percent (100X, AM0, temperature T = 28 C). Although the cells are designed for operation at this concentration, peak efficiency is observed near 300 suns (eta = 25.1 percent). To our knowledge, this is the highest reported solar cell efficiency for space applications. The improvement in efficiency over that reported at the previous SPRAT conference is attributed primarily to lower series resistance and improved grid-line plating procedures. Using previously measured temperature coefficients, researchers estimate that the n-p GaAs cells should deliver approximately 22.5 percent efficiency at the operating conditions of 100 suns and T = 80 C. This performance exceeds the NASA program goal of 22 percent for the Cassegrainian cell. One hundred Cassegrainian cells have been sent to NASA as deliverables, sixty-eight in the n-p configuration and thirty-two in the p-n configuration

Public awareness and engagement in relation to the coastal oil spill in northeast Brazil

Social media data is a rich source of information to assess human activities in catastrophic events. Here, we use social media data to understand how the 2019 Brazilian oil spill influenced social attitudes. Data were collected from the globally popular Instagram platform between August 1, 2019 and March 1, 2020. First, we manually identified the 5 most popular (portuguese language) hashtags related to the oil spill #oleonononordeste;#desastreambiental;#ma rsemoleo;#sosnordeste;#ma rsempetroleo. In the sequence, we collected information on captions, post metadata and users associated with posts retrieved using the selected hashtags. We identified a total of 7,413 posts. These posts were grouped in topics: government (47.76%), protest (24.37%), volunteers (24.45%), biodiversity (0.003%), origin (0.006%), tourism (0.008%) and others (0.016%). All topics had the peak of posts in October and November 2019. Nevertheless, interest in the oil spill was temporary, with most posts appearing in the 2-4 months after the beginning of the disaster. Our findings illustrate the enormous potential of using social media data for understanding and monitoring human engagement with environmental disasters, but also suggest that conservationists and environmental groups may only have a limited 'window of opportunity' to engage and mobilize public support for remediation and restoration efforts.Peer reviewe

A big data approach to identify the loss of coastal cultural ecosystem services caused by the 2019 Brazilian oil spill disaster

In August 2019, the Northeast coast of Brazil was impacted by an extensive oil spill, with immediate effects on marine and coastal ecosystems and significant impacts on tourism and food security. The human dimension of those impacts also includes the loss of cultural ecosystem services (CES); the non-material benefits stemming from strongly rooted cultural practices and relationships with nature. CES are of great importance for local residents and visitors that flock to Brazilian iconic beaches, however, they are difficult to measure using traditional assessment methods due to their subjective and non-tangible nature. Here, we use a big data approach to assess and map the loss of CES in the Northeast coast of Brazil caused by the recent oil spill. We analysed 2,880 digital images (published on the image sharing platform Flickr) taken before and during the disaster in affected locations, using a combination of automated techniques. Results showed a sharp decline in the number of users posting photos of locations affected by oil spill, and a decline in photos representing landscape and cultural appreciation. Our big data approach provides a fast and automated way to assess CES at large spatial scales that can be used to monitor the social impacts of environmental disasters.Peer reviewe

Spondias mombin as a reservoir of fruit fly parasitoid populations in the Eastern Amazon: an undervalued ecosystem service.

Fruit flies are economically important pests that infest a wide variety of host trees. The environmental damage caused by traditional pesticide-based control methods has prompted scientists to seek less damaging alternatives such as biological control by native species. Parasitoids, especially Braconidae species, have excellent potential as biological control agents for fruit flies, being both generalists and well distributed geographically. Native fruit trees that support medium or high levels of these parasitoids could therefore play an important role in biological control strategies. A good potential example is Spondias mombin L. in the Brazilian Amazon, which hosts several species of fruit flies and associated parasitoids. Here, we provide a unique synthesis of over nearly two decades of data from the east Amazon, clearly demonstrating the potential of S. mombin to act as a source and reservoir of fruit fly parasitoids. This important ecosystem service (biological control) provided by the parasitoids and supported by S. mombin could be further enhanced through conservation of this plant species in its natural environment

Local and regional drivers influence how aquatic community diversity, resistance and resilience vary in response to drying

Disturbance events govern how the biodiversity of ecological communities varies in both space and time. In freshwater ecosystems, there is evidence that local and regional‐scale drivers interact to influence ecological responses to drying disturbances. However, most research provides temporal snapshots at the local scale, whereas few studies encompass a gradient of drying severity spanning multiple years. Using a dataset of rare spatiotemporal extent and detail, we demonstrate how independent and interacting local and regional‐scale factors drive shifts in the α and β diversities of communities in dynamic river ecosystems. We examined aquatic invertebrate assemblage responses to hydrological variability (as characterized by monthly observations of instream conditions) at 30 sites over a 12‐year period encompassing typical years and two severe drought disturbances. Sites varied in their disturbance regimes and hydrological connectivity at both local (i.e. site‐specific) and regional (i.e. river catchment) scales. Whereas α diversity was mainly influenced by local factors including flow permanence and the temporal extent of ponded and dry conditions, both temporal and spatial β diversities also responded to regional‐scale metrics such as the spatial extent of flow and hydrological connectivity. We observed stronger local negative responses for taxa with lower capacities to tolerate drying (i.e. resistance) and/or to recover after flow resumes (i.e. resilience), whereas taxa with functional traits promoting resilience made an increasing contribution to spatial β diversity as hydrological connectivity declined. As droughts increase in extent and severity across global regions, our findings highlight the functional basis of taxonomic responses to disturbance and connectivity, and thus advance understanding of how drying disturbances shape biodiversity in river networks. Our identification of the role of regional hydrological factors could inform catchment‐scale management strategies that support ecosystem resilience in a context of global change