Bat species eaten by people in central Africa show evidence of symptomless Ebola infection.

Fruit bats as reservoirs of Ebola virus

Electrons move in solids at very high speed — traversing atomic layers and interfaces within tens to hundreds of attoseconds (an attosecond is a billionth of a billionth of a second). These astonishingly brief travel times will ultimately limit the speed of the electronics of the future. Physicists have now experimentally probed such electron dynamics in real time. The cover illustrates the first attosecond spectroscopic measurement in a solid, revealing a 110-attosecond difference in the travel time of two different types of electrons following photoexcitation in a tungsten crystal. The ability to time electrons moving in solids over merely a few interatomic distances makes it possible to probe the solid-state electronic processes occurring at the ultimate speed limit and thus helps to advance technologies such as computation, data storage and photovoltaics, which all rely on exquisite control of electron transport in ever smaller structures of solid matter. When exposing a tungsten crystal to intense light, the travel times of emitted electrons differ by 110 attoseconds, depending on whether they were originally tightly bound to one atom in the crystal or delocalized over many atoms. This ability to directly probe fundamental aspects of solid-state electron dynamics could aid the further development of modern technologies such as electronics, information processing and photovoltaics. Comprehensive knowledge of the dynamic behaviour of electrons in condensed-matter systems is pertinent to the development of many modern technologies, such as semiconductor and molecular electronics, optoelectronics, information processing and photovoltaics. Yet it remains challenging to probe electronic processes, many of which take place in the attosecond (1 as = 10-18 s) regime. In contrast, atomic motion occurs on the femtosecond (1 fs = 10-15 s) timescale and has been mapped in solids in real time1,2 using femtosecond X-ray sources3. Here we extend the attosecond techniques4,5 previously used to study isolated atoms in the gas phase to observe electron motion in condensed-matter systems and on surfaces in real time. We demonstrate our ability to obtain direct time-domain access to charge dynamics with attosecond resolution by probing photoelectron emission from single-crystal tungsten. Our data reveal a delay of approximately 100 attoseconds between the emission of photoelectrons that originate from localized core states of the metal, and those that are freed from delocalized conduction-band states. These results illustrate that attosecond metrology constitutes a powerful tool for exploring not only gas-phase systems, but also fundamental electronic processes occurring on the attosecond timescale in condensed-matter systems and on surfaces.

Attosecond spectroscopy in condensed matter

Several human and animal Ebola outbreaks have occurred over the past 4 years in Gabon and the Republic of Congo. The human outbreaks consisted of multiple simultaneous epidemics caused by different viral strains, and each epidemic resulted from the handling of a distinct gorilla, chimpanzee, or duiker carcass. These animal populations declined markedly during human Ebola outbreaks, apparently as a result of Ebola infection. Recovered carcasses were infected by a variety of Ebola strains, suggesting that Ebola outbreaks in great apes result from multiple virus introductions from the natural host. Surveillance of animal mortality may help to predict and prevent human Ebola outbreaks.

https://science.sciencemag.org/content/sci/303/5656/387.full.pdf

Multiple Ebola Virus Transmission Events and Rapid Decline of Central African Wildlife

In an age of accelerating biodiversity loss, this timely and critical volume summarizes recent advances in biodiversity-ecosystem functioning research and explores the economics of biodiversity and ecosystem services. The book starts by summarizing the development of the basic science and provides a meta-analysis that quantitatively tests several biodiversity and ecosystem functioning hypotheses. It then describes the natural science foundations of biodiversity and ecosystem functioning research including: quantifying functional diversity, the development of the field into a predictive science, the effects of stability and complexity, methods to quantify mechanisms by which diversity affects functioning, the importance of trophic structure, microbial ecology, and spatial dynamics. Finally, the book takes research on biodiversity and ecosystem functioning further than it has ever gone into the human dimension, describing the most pressing environmental challenges that face humanity and the effects of diversity on: climate change mitigation, restoration of degraded habitats, managed ecosystems, pollination, disease, and biological invasions.However, what makes this volume truly unique are the chapters that consider the economic perspective. These include a synthesis of the economics of ecosystem services and biodiversity, and the options open to policy-makers to address the failure of markets to account for the loss of ecosystem services; an examination of the challenges of valuing ecosystem services and, hence, to understanding the human consequences of decisions that neglect these services; and an examination of the ways in which economists are currently incorporating biodiversity and ecosystem functioning research into decision models for the conservation and management of biodiversity. A final section describes new advances in ecoinformatics that will help transform this field into a globally predictive science, and summarizes the advancements and future directions of the field. The ultimate conclusion is that biodiversity is an essential element of any strategy for sustainable development.

Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective

An intact forest landscape (IFL) is a seamless mosaic of forest and naturally treeless ecosystems with no remotely detected signs of human activity and a minimum area of 500 km2. IFLs are critical for stabilizing terrestrial carbon storage, harboring biodiversity, regulating hydrological regimes, and providing other ecosystem functions. Although the remaining IFLs comprise only 20% of tropical forest area, they account for 40% of the total aboveground tropical forest carbon. We show that global IFL extent has been reduced by 7.2% since the year 2000. An increasing rate of global IFL area reduction was found, largely driven by the tripling of IFL tropical forest loss in 2011–2013 compared to that in 2001–2003. Industrial logging, agricultural expansion, fire, and mining/resource extraction were the primary causes of IFL area reduction. Protected areas (International Union for Conservation of Nature categories I to III) were found to have a positive effect in slowing the reduction of IFL area from timber harvesting but were less effective in limiting agricultural expansion. The certification of logging concessions under responsible management had a negligible impact on slowing IFL fragmentation in the Congo Basin. Fragmentation of IFLs by logging and establishment of roads and other infrastructure initiates a cascade of changes that lead to landscape transformation and loss of conservation values. Given that only 12% of the global IFL area is protected, our results illustrate the need for planning and investment in carbon sequestration and biodiversity conservation efforts that target the most valuable remaining forests, as identified using the IFL approach.

The last frontiers of wilderness: Tracking loss of intact forest landscapes from 2000 to 2013

Because rapidly expanding human populations have devastated gorilla (Gorilla gorilla) and common chimpanzee (Pan troglodytes) habitats in East and West Africa, the relatively intact forests of western equatorial Africa have been viewed as the last stronghold of African apes1. Gabon and the Republic of Congo alone are thought to hold roughly 80% of the world's gorillas2 and most of the common chimpanzees1. Here we present survey results conservatively indicating that ape populations in Gabon declined by more than half between 1983 and 2000. The primary cause of the decline in ape numbers during this period was commercial hunting, facilitated by the rapid expansion of mechanized logging. Furthermore, Ebola haemorrhagic fever is currently spreading through ape populations in Gabon and Congo and now rivals hunting as a threat to apes. Gorillas and common chimpanzees should be elevated immediately to ‘critically endangered’ status. Without aggressive investments in law enforcement, protected area management and Ebola prevention, the next decade will see our closest relatives pushed to the brink of extinction.

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Sosthéne Ndong Obiang

Papers

Catastrophic ape decline in western equatorial Africa