925 research outputs found
Possible wave formation and martensitic transformation of iron particles in copper single crystals during argon ion bombardment
Chapter 15: Potential Surprises: Compound Extremes and Tipping Elements
The Earth system is made up of many components that interact in complex ways across a broad range of temporal and spatial scales. As a result of these interactions the behavior of the system cannot be predicted by looking at individual components in isolation. Negative feedbacks, or self-stabilizing cycles, within and between components of the Earth system can dampen changes (Ch. 2: Physical Drivers of Climate Change). However, their stabilizing effects render such feedbacks of less concern from a risk perspective than positive feedbacks, or self-reinforcing cycles. Positive feedbacks magnify both natural and anthropogenic changes. Some Earth system components, such as arctic sea ice and the polar ice sheets, may exhibit thresholds beyond which these self-reinforcing cycles can drive the component, or the entire system, into a radically different state. Although the probabilities of these state shifts may be difficult to assess, their consequences could be high, potentially exceeding anything anticipated by climate model projections for the coming century
Temperature Changes in the United States
Temperature is among the most important climatic elements used in decision-making. For example, builders and insurers use temperature data for planning and risk management while energy companies and regulators use temperature data to predict demand and set utility rates. Temperature is also a key indicator of climate change: recent increases are apparent over the land, ocean, and troposphere, and substantial changes are expected for this century. This chapter summarizes the major observed and projected changes in near-surface air temperature over the United States, emphasizing new data sets and model projections since the Third National Climate Assessment (NCA3). Changes are depicted using a spectrum of observations, including surface weather stations, moored ocean buoys, polar-orbiting satellites, and temperature-sensitive proxies. Projections are based on global models and downscaled products from CMIP5 (Coupled Model Intercomparison Project Phase 5) using a suite of Representative Concentration Pathways (RCPs; see Ch. 4: Projections for more on RCPs and future scenarios)
Contingent infrastructure and the dilution of âChinesenessâ: Reframing roads and rail in Kampala and Addis Ababa
Amid growing interest in Chinaâs role in financing and building infrastructure in Africa, there is still little research on how Chinese-financed infrastructures are negotiated and realised at the city and metropolitan scale. We compare the Light Rail Transit in Addis Ababa, Ethiopia with the expressway linking Kampala to Entebbe airport in Uganda, examining the processes of bargaining behind these transport infrastructures and their emergent effects on urban land use and city-dwellersâ mobility. We find that both projects were designed and implemented through opaque negotiations between African national elites and Chinese agencies, with little or no engagement from city authorities, leading to haphazard outcomes that are poorly integrated with broader planning. Yet we also suggest that despite being enabled and mediated by Chinese agencies, such projects do not embody a Chinese global vision. They instead reflect the entrepreneurial activities of Chinese contractors and the varying ways in which these connect with African national governmentsâ shifting priorities. Moreover, as they are subsumed into the urban context, these transposed infrastructures have been rapidly repurposed and their âChinesenessâ diluted, with one morphing into an infrastructure for the poor and the other into a site of private value extraction. We thus argue that, far from representing a domineering or neo-colonial influence, Chinese-financed infrastructures that land in institutionally complex African city-regions can be rapidly swallowed up into the political-economic landscape, producing contingent benefits and disbenefits that are far removed from the visions of any planners â Chinese or African, past or present
Face-centred cubic to body-centred cubic martensitic transformation of Fe-Co particles in a copper matrix
Local climate determines vulnerability to camouflage mismatch in snowshoe hares
AimPhenological mismatches, when lifeâevents become mistimed with optimal environmental conditions, have become increasingly common under climate change. Populationâlevel susceptibility to mismatches depends on how phenology and phenotypic plasticity vary across a speciesâ distributional range. Here, we quantify the environmental drivers of colour moult phenology, phenotypic plasticity, and the extent of phenological mismatch in seasonal camouflage to assess vulnerability to mismatch in a common North American mammal.LocationNorth America.Time period2010â2017.Major taxa studiedSnowshoe hare (Lepus americanus).MethodsWe used >Â 5,500 byâcatch photographs of snowshoe hares from 448 remote camera trap sites at three independent study areas. To quantify moult phenology and phenotypic plasticity, we used multinomial logistic regression models that incorporated geospatial and highâresolution climate data. We estimated occurrence of camouflage mismatch between haresâ coat colour and the presence and absence of snow over 7Â years of monitoring.ResultsSpatial and temporal variation in moult phenology depended on local climate conditions more so than on latitude. First, hares in colder, snowier areas moulted earlier in the fall and later in the spring. Next, hares exhibited phenotypic plasticity in moult phenology in response to annual variation in temperature and snow duration, especially in the spring. Finally, the occurrence of camouflage mismatch varied in space and time; white hares on dark, snowless background occurred primarily during lowâsnow years in regions characterized by shallow, shortâlasting snowpack.Main conclusionsLongâterm climate and annual variation in snow and temperature determine coat colour moult phenology in snowshoe hares. In most areas, climate change leads to shorter snow seasons, but the occurrence of camouflage mismatch varies across the speciesâ range. Our results underscore the populationâspecific susceptibility to climate changeâinduced stressors and the necessity to understand this variation to prioritize the populations most vulnerable under global environmental change.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154444/1/geb13049.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154444/2/geb13049_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154444/3/geb13049-sup-0001-Supinfo.pd
Our Globally Changing Climate
Since the Third U.S. National Climate Assessment (NCA3) was published in May 2014, new observations along multiple lines of evidence have strengthened the conclusion that Earth's climate is changing at a pace and in a pattern not explainable by natural influences. While this report focuses especially on observed and projected future changes for the United States, it is important to understand those changes in the global context (this chapter). The world has warmed over the last 150 years, especially over the last six decades, and that warming has triggered many other changes to Earth's climate. Evidence for a changing climate abounds, from the top of the atmosphere to the depths of the oceans. Thousands of studies conducted by tens of thousands of scientists around the world have documented changes in surface, atmospheric, and oceanic temperatures; melting glaciers; disappearing snow cover; shrinking sea ice; rising sea level; and an increase in atmospheric water vapor. Rainfall patterns and storms are changing, and the occurrence of droughts is shifting
Dose-Additive Carcinogenicity of a Defined Mixture of âDioxin-like Compoundsâ
Use of the dioxin toxic equivalency factor (TEF) approach in human risk assessments assumes that the combined effects of dioxin-like compounds in a mixture can be predicted based on a potency-adjusted dose-additive combination of constituents of the mixture. In this study, we evaluated the TEF approach in experimental 2-year rodent cancer bioassays with female Harlan Sprague-Dawley rats receiving 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3,3âČ,4,4âČ,5-pentachlorobiphenyl (PCB-126), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of the three compounds. Statistically based doseâresponse modeling indicated that the shape of the doseâresponse curves for hepatic, lung, and oral mucosal neoplasms was the same in studies of the three individual chemicals and the mixture. In addition, the dose response for the mixture could be predicted from a combination of the potency-adjusted doses of the individual compounds. Finally, we showed that use of the current World Health Organization dioxin TEF values adequately predicted the increased incidence of liver tumors (hepatocellular adenoma and cholangiocarcinoma) induced by exposure to the mixture. These data support the use of the TEF approach for dioxin cancer risk assessments
Corrigendum: A Meta-Analysis of the Effect of Bacillus Calmette-Guérin Vaccination Against Bovine Tuberculosis:Is Perfect the Enemy of Good?
More than 50 million cattle are likely exposed to bovine tuberculosis (bTB) worldwide, highlighting an urgent need for bTB control strategies in low- and middle-income countries (LMICs) and other regions where the disease remains endemic and test-and-slaughter approaches are unfeasible. While Bacillus Calmette-GuĂ©rin (BCG) was first developed as a vaccine for use in cattle even before its widespread use in humans, its efficacy against bTB remains poorly understood. To address this important knowledge gap, we conducted a systematic review and meta-analysis to determine the direct efficacy of BCG against bTB challenge in cattle, and performed scenario analyses with transmission dynamic models incorporating direct and indirect vaccinal effects (âherd-immunityâ) to assess potential impact on herd level disease control. The analysis shows a relative risk of infection of 0.75 (95% CI: 0.68, 0.82) in 1,902 vaccinates as compared with 1,667 controls, corresponding to a direct vaccine efficacy of 25% (95% CI: 18, 32). Importantly, scenario analyses considering both direct and indirect effects suggest that disease prevalence could be driven down close to Officially TB-Free (OTF) status (<0.1%), if BCG were introduced in the next 10-year time period in low to moderate (<15%) prevalence settings, and that 50â95% of cumulative cases may be averted over the next 50 years even in high (20â40%) disease burden settings with immediate implementation of BCG vaccination. Taken together, the analyses suggest that BCG vaccination may help accelerate control of bTB in endemic settings, particularly with early implementation in the face of dairy intensification in regions that currently lack effective bTB control programs
Below the Belt? Territory and Development in Chinaâs International Rise
Chinaâs internationalization has been heralded by some as a new era of SouthâSouth cooperation. Yet such framings of development are pitched at an abstract space of the âglobal Southâ which conceals more than it reveals. With some theory moving towards ontologies of âglobal developmentâ, we need to capture both the connectedness and the local specificity of increasingly diffuse processes. This article sets out a more fine-grained understanding of how political territories and processes are imagined and produced by and through Chinaâs internationalization, focusing on infrastructure as a âtechnologyâ of territorialization. Much of the focus on Chinaâs internationalization has been on state-to-state relations, but this obscures the âomni-channel politicsâ that China practises. Using a critical literature review and illustrative case study, this article develops the idea of omni-channel politics to posit a view of âtwistedâ territories in which political processes and development outcomes are more complex and contingent
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