Fabric analysis of Allende matrix using EBSD

Abstract— Fabric analysis of the interstitial matrix material in primitive meteorites offers a novel window on asteroid formation and evolution. Electron backscatter diffraction (EBSD) has allowed fabrics in these fine‐grained materials to be visualized in detail for the first time. Our data reveal that Allende, a CV3 chondrite, possesses a uniform, planar, short‐axis alignment fabric that is pervasive on a broad scale and is probably the result of deformational shortening related to impact or gravitational compaction. Interference between this matrix fabric and the larger, more rigid components, such as dark inclusions (DIs) and calcium‐aluminium‐rich inclusions (CAIs), has lead to the development of locally oriented and intensified matrix fabrics. In addition, DIs possess fabrics that are conformable with the broader matrix fabric. These results suggest that DIs were in situ prior to the deformational shortening event responsible for these fabrics, thus providing an argument against dark inclusions being fragments from another lithified part of the asteroid (Kojima and Tomeoka 1996; Fruland et al. 1978). Moreover, both DIs and Allende matrix are highly porous (?25%) (Corrigan et al. 1997). Mobilizing a highly porous DI during impact‐induced brecciation without imposing a fabric and incorporating it into a highly porous matrix without significantly compacting these materials is improbable. We favor a model that involves Allende DIs, CAIs, and matrix accreting together and experiencing the same deformation events.     

Looking for a White Male Effect in Generation Z: Race,Gender, and Political Effects on Environmental Concern and Ambivalence

The “White male effect” has been presented in past literature as a way to explain the tendency for White males to have lower environmental concern and risk perceptions than female and non-White individuals. Recently, research has proposed the “White male effect” may be a “conservative White male effect,” due to findings that political ideology impacts environmental concern. This study used a sample of young college-educated adults from Generation Z to test whether the conservative White male effect is present for environmental concern and ambivalence toward a proenvironmental worldview in this younger generation. Online surveys were distributed to undergraduate students at a large northeastern university in spring of 2016. A total of 1,940 surveys were returned. Results showed a lack of a unique White male, or conservative White male, effect above and beyond differences explained by gender, Whiteness, and political affiliation. The implications of this effect’s absence are discussed.     

Ecosystem Services in a Transitional Forest Landscape: Shifting Trajectories in Southeast Michigan,USA

North American forests provide multiple ecosystem services, such as carbon storage, biodiversity, and recreation. These services are often coordinated through multifunctional management, whereby various users and owners contribute to collective agendas. Forests in exurban “transition” zones are crucial components in the sustainability of broader metropolitan landscapes, but represent a particularly understudied confluence of ecosystem services and multifunctional management. In this paper, we develop a place-based approach to assess ecosystem services in transitional forests (those between rural and urban). We demonstrate how trajectories of forest composition are linked with shifting ecosystem services that both shape and are shaped by management activities. Sited in Stinchfield Woods, a forest in southeast Michigan, this study draws on a household survey, interviews, ecological data, and archival information. Given variations in priorities over time and among different users, we suggest that coordinated, adaptive management may improve provisioning of ecosystem services in ways that benefit multiple users.     

Is public awareness and perceived threat of climate change associated with governmental mitigation targets?

Social scientists and science communicators are concerned about the apparent discrepancy between the scientific consensus on climate change (Anderegg et al. Proc Natl Acad Sci 107:12107–12109, 2010; Doran and Zimmerman EOS Trans Am Geophys Union 90:22–3, 2009) and the general public’s views (Knight Environ Sociol 2:101–113, 2016; Lee et al. Nat Clim Chang 5:1014–1020, 2015). It is reasoned that increased public awareness and perceived threat of climate change may pressure governments to enact policy to counteract climate change (e.g. setting stringent carbon emissions targets). Despite a logical link between public awareness and government-set emissions targets, this relationship remains untested. We examined the relationship between public awareness about and perceived threat of climate change and governmental emissions targets across 71 countries and 1 region. We found a positive association between the proportions of a country’s population that are aware of climate change and the unconditional emissions reduction targets set by that country in the Paris Agreement (Rogelj et al. Nature 534:631–639, 2016). However, the proportion of people in a country who perceive climate change as a personal threat was not associated with higher emissions reduction targets. Our results suggest that public awareness may be an important part of garnering the public support required for policies designed to mitigate climate change to succeed.     

The Role of Sediment Dynamics for Inorganic Accretion Patterns in Southern California’s Mediterranean-Climate Salt Marshes

Salt marsh resilience to sea-level rise depends on marsh plain elevation, tidal range, subsurface processes, as well as surface accretion, of which suspended-sediment concentration (SSC) is a critical component. However, spatial and temporal patterns of inorganic sedimentation are poorly quantified within and across Salicornia pacifica (pickleweed)-dominated marshes. We compared vertical accretion rates and re-examined previously published suspended-sediment patterns during dry-weather periods at Seal Beach Wetlands, which is characterized by a mix of Spartina foliosa (cordgrass) and pickleweed, and for Mugu Lagoon, where cordgrass is rare. Mugu Lagoon occurs higher in the tidal frame and receives terrigenous sediment from an adjacent creek. Feldspar marker horizons were established in winter 2013–2014 to measure accretion. Accretion rates at Seal Beach Wetlands and Mugu Lagoon were 6 ± 0.5 mm/year (mean ± SE) and 2 ± 0.3 mm/year. Also, the estimated sediment flux (g/year) across the random feldspar plots was 3.5 times higher at Seal Beach Wetlands. At Mugu Lagoon, accretion was higher near creeks, although not statistically significant. Dry-weather SSC showed similar concentrations at transect locations across sites. During wet weather, however, SSC at Mugu Lagoon increased at all locations, with concentrations decaying farther than 8 m from tidal creek edge. Based on these results from Mugu Lagoon, we conclude accretion patterns are set by infrequent large flooding events in systems where there is a watershed sediment source. Higher accretion rates at Seal Beach Wetlands may be linked to lower-marsh elevations, and thus more frequent inundation, compared with Mugu Lagoon.     

Thule Fishing Revisited: The Economic Importance of Fish at the Pembroke and Bell Sites,Victoria Island,Nunavut

Geografisk Tidsskrift—Danish Journal of Geography 110(2):261–278, 2010

In a comprehensive overview of evidence for fishing in the Thule period of the eastern North American Arctic, Whitridge (2001) noted that fish bones are either extremely rare or absent in archaeofaunal samples, despite the fact that artifact assemblages typically contain a variety of fishing implements. In this paper, we present new faunal data from two sites on southeastern Victoria Island, Nunavut, which offer a marked contrast to this pattern. The Pembroke site, located just north of Cambridge Bay, is a small Thule site probably occupied during an early migration into the region. The Bell site, located on the Ekalluk River, is a more substantial site, occupied for a much longer duration during the Thule period. These sites are located in areas devoid of many taxa preferred by Thule peoples, which led the sites' occupants to rely on caribou and fish for much of their winter subsistence. At the Bell site, storage of caribou and fish was critical for winter survival. However, the occupants of the Pembroke site appear to have been unable to acquire sufficient stores during the fall, and therefore relied on fishing through the ice during winter to supplement their inadequate stores. Although both sites indicate a more important economic role for fish than has been recorded on any other eastern Arctic Thule winter site, the use of fish at the two sites differs markedly, adding nuance to archaeologically known Thule subsistence patterns.     

Hypsographic Demography Across Scale

The typical framework for assessing human population distribution is across a flat, two-dimensional landscape. We alter this perspective by examining population distribution with respect to a third dimension, elevation. This alternative framework, termed hypsographic demography, conceptually provides a more complete visualization and understanding of population distribution. We apply hypsographic demography to North Carolina from the scale of the entire state to streams of different sizes. At the state scale, elevation and population are generally inversely correlated. The flat coastal plain contains the majority of the population at low elevations, whereas higher elevations contain smaller populations due to steep topography, which limits development. At the county scale, the historic location and expansion of cities was more closely correlated with observed patterns of hypsographic demography than elevation or topography. At the scale of the stream, the influence of topography on hypsographic demographics gains importance where topography limits the land available to develop. We use this approach to illustrate how changing the perspective for viewing population distribution can be applied to floodplain policy.     

Landscape,development, technology and drivers: The geography of drownings associated with automobiles in Texas floods, 1950–2004

More than 200 people have died in automobiles that have encountered flooded roadways in Texas from 1950 to 2004. This study examines the geographical processes that create flood hazards associated with automobile travel to discern the most important factors in their genesis. A database of drowning cases caused by motorists' interactions with flooded roadways in Texas was compiled for the study period. We examine the circumstances and spatial patterns of these events by addressing the following questions: where have motorists drowned? How did rates and spatial patterns of accidents change over the study period? To the extent that we can determine, what were the characteristics of the roads, the drivers, and the landscapes when and where deaths occurred? What factors appear to explain the temporal and spatial distributions of hazard? We conclude that roadway familiarity might have emboldened drivers to attempt to surmount water rushing across a road, that time of day was clearly an important characteristic of the accidents, and that roadway characteristics and sex and age of the drivers seem not to be key contributing factors. The most important factors, however, are associated with growth: increases in population and increased automobile registrations drive the propensity for increased automobile-flood hazards.