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Atomic mixing by replacement collision sequences and other cascade effects is well known to create chemical disorder in irradiated alloys. Most studies of irradiation-induced disordering have focused on ex situ analysis of irradiated samples; however, fast in situ techniques are necessary to measure disordering at elevated temperatures without significant interference from concurrent re-ordering processes. In the present work, we use in situ electron diffraction with high speed data collection to measure the initial change in the long-range order parameter S with ion dose ϕ during 500 keV Ne+ irradiation of Cu3Au foils. The data reveal an unexpected and dramatic increase in the disordering rate as the critical order–disorder transition temperature TC is approached. Molecular dynamics simulations show that this increase is not due to temperature-dependent cascade mixing. We attribute the enhanced disordering, instead, to coupling between point defect fluxes and the chemical state of order.
Ba-rich and Si-rich phlogopites occur in the talc-bearing rocks of the La Creuse sulfide ore deposit in Beaujolais, France. They form a group of compositions completely separated from the common Al-rich phlogopites that occur in the surrounding talc-free metasiltites and metarhyolites, with higher Ba and Mg and lower Al contents. The Ba-rich phlogopites have a relatively narrow compositional range (0.24 to 0.80 Ba per formula unit, for 44 valencies) with high and constant Si (5.8 atoms per formula unit, apfu) and Mg + Fe (5.6 apfu), probably buffered by the presence of talc. Compared to low-Al phlogopites from talc-free rocks, the excess charge introduced by the BaK–1 substitution is compensated by interlayer vacancies. Such a high level of interlayer vacancy (0.56 pfu), related to the talc-producing metasomatic conditions, is essential for the stability of this special group of Ba-rich and Si-rich phlogopites.
Single crystal X-ray diffraction analyses were performed. Ba-rich and Si-rich phlogopite is monoclinic, space group C2/m, (R = 5.31%) with a = 5.3185(5), b = 9.2136(9), c = 10.1349(11) Å and β = 100.131(11)°. The occupancies of Mg/Fe and K/Ba were refined exploring different vacancies. The solutions giving the best R factor (4.77%) and goodness-of-fit (1.06) are obtained with 15% < vacancy < 40% at the interlayer site.
Malaysia has an ageing population and an increasing number of older people who live alone. This study explores the social support and care arrangements of older people living alone in rural Malaysia. The study took a qualitative approach: semi-structured interviews were conducted with a purposive sample of Malay (N = 20) and Chinese (N = 20) Malaysians aged over 65. Five cross-cutting themes were identified through a thematic analysis: degrees of aloneness; relationships and social support; barriers to social support; and future illness, care and death. All participants said they lived alone; living arrangements, however, were often complex. For Malays, most support came from nearby adult children and relatives, whereas Chinese participants, who less frequently had adult children living locally, emphasised support from friends and neighbours. Emigrant adult children's assistance was mostly informational and financial, instrumental assistance was either substituted for money, or provided solely during periods of ill-health. Physical decline, limited telephone use, inadequate transportation and fears of crime were barriers to social support. Participants avoided thinking or talking about future care needs. These findings have implications for Malaysian old age policy, which is currently focused on supporting families to care for older relatives. Child migration and a growing preference for a period of independent living in old age may require policies and resources directed at older people as individuals to support their own efforts to remain independent, active and age ‘in place’.
Group III nitrides are promising materials for light emitting diodes (LEDs). The occurrence of structural defects strongly affects the efficiency of these LEDs. We investigate the optical properties of basal plane stacking faults (BFSs), and the assignment of specific spectral features to distinct defect types by direct correlation of localized emission bands measured by cathodoluminescence in a scanning electron microscope with defects found in high resolution (scanning) transmission electron microscopy and electron beam induced current at identical sample spots. Thus, we are able to model the electronic structure of BSFs addressing I1, I2, and E type BSFs in GaN and AlGaN with low Al content. We find hints that BSFs in semipolar AlGaN layers cause local changes of the Al content, which strongly affects the usability of AlGaN as an electron blocking layer in nitride based LEDs.
Cu90Ag10 alloys were subjected to severe plastic deformation at temperatures ranging from 25 to 400 °C and strain rates ranging from 0.1 to 6.25 s−1 using high-pressure torsion. The deformed samples were characterized by x-ray diffraction, transmission electron microscopy, and atom-probe tomography. A dynamic competition between shear-induced mixing and thermally activated decomposition led to the self-organization of the Cu–Ag system at length scales varying from a few atomic distances at room temperature to ≈50 nm at 400 °C. Steady-state microstructural length scales were minimally affected by varying the strain rate, although at 400 °C, the grain morphology did depend on strain-rate. Our results show that diffusion below 300 °C is dominated by nonequilibrium vacancies, and by comparison with previous Kinetic Monte Carlo simulations [D. Schwen et al., J. Mater. Res.28, 2687–2693 (2013)], their concentration could be obtained.
A gastropod fauna has been studied from upper Pliensbachian – upper Toarcian deposits of two sections of the Causses Basin (southern France) in order to investigate the mode of recovery after the early Toarcian anoxic event. The fauna consists of 15 species, one of which is new (Bathrotomaria kronzwilmesorum sp. nov.). Their stratigraphical distribution shows two peaks of diversity – in the Bifrons Zone (Bifrons Subzone) and in the Aalensis Zone (Mactra Subzone) – which reflect brief times during which the oxygen content and bottom consistency favoured the settlement of a relatively diversified fauna. In the Variabilis–Pseudoradiosa zones, gastropods are only represented by two species. This probably indicates more severe and unstable environmental conditions, only allowing the survival of gastropod taxa with wide adaptive capacities. The very low species diversity and the discontinuous and slow faunal recovery were probably determined by physiographic factors. The Causses area was a small basin confined by exposed lands and open towards the central part of western Tethys. Gastropods described here occur exclusively in the Toarcian – early Aalenian communities of the European epicontinental seas, whereas species from the central region of western Tethys are absent. Geographic isolation and marginal location of the Causses Basin restricted faunal exchange with the western European epicontinental seas, preventing fast recovery after the anoxic event. Gastropods of the central region of the western Tethys were probably unable to settle and colonize that area due to the strongly different environment.
The nanoscale precipitation induced by 1.8 MeV ion irradiation in Cu1−xVx thin films, with x ≈ 0.09 and 0.91, was studied by atom probe tomography. For the Cu91V9 alloys, irradiation in the range of 300–500 °C led to steady-state compositional patterning of V-rich nanoprecipitates. V nanoprecipitates larger than ∼10 nm in diameter, moreover, contained Cu-rich cores, resulting in an unusual “cherry-pit” nanostructure. The number of these pits within one precipitate increased with the precipitate size, but with the volume fraction of pits within a given precipitate remaining roughly constant, from ∼1.5 to 5%. Similar irradiations performed on V91Cu9 also resulted in an enhanced precipitation reaction, but with smaller Cu-rich nanoprecipitates, <3 nm in diameter, and no “cherry pits.” These results are rationalized using recent atomistic simulations that have explored the conditions for stabilizing by ion irradiation “cherry-pit” nanostructures in immiscible A–B alloy systems, such as Cu–V.
The avoidability of binary patterns by binary cube-free words is investigated and the exact bound between unavoidable and avoidable patterns is found. All avoidable patterns are shown to be D0L-avoidable. For avoidable patterns, the growth rates of the avoiding languages are studied. All such languages, except for the overlap-free language, are proved to have exponential growth. The exact growth rates of languages avoiding minimal avoidable patterns are approximated through computer-assisted upper bounds. Finally, a new example of a pattern-avoiding language of polynomial growth is given.
Compositional patterning in two-phase immiscible alloys during severe plastic deformation at elevated temperatures has been investigated. Kinetic Monte Carlo computer simulations were used to test the proposed idea that patterning derives from a dynamic competition between homogenization by forced chemical mixing and phase separation by thermally activated diffusion [P. Bellon and R.S. Averback, Phys. Rev. Lett.74, 1819 (1995) and F. Wu et al., Acta Mater.54, 2605 (2006)]. We utilize the concept of pair diffusion coefficients to compare thermal diffusion with forced chemical mixing and discuss the fundamentally different behavior with respect to pair separation distance in both mechanisms. While the general ideas of this model are verified and are in good quantitative agreement with our simulations, it is found that the dynamic processes of alloys under high-temperature shear are very complex, even in highly idealized systems, making experimental verification of this model very difficult. We illustrate our findings for a model AB alloy with properties similar to Cu–Ag by showing how alloy morphology and solubility depend on shear rate, temperature, and composition.
With the precise, nearly-continuous photometry from the Kepler satellite and the sub-milliarcsecond resolving capabilities of the CHARA Array, astronomy is entering a new age for the imaging and understanding of stellar magnetic activity. We present first results from our Guest Observer Program, where 180 single-epoch surface image reconstructions of KIC 5110407 have revealed differential rotation and hints of magnetic activity cycles based on both spot and flare variations. Analysis of our larger, full dataset will establish in unprecedented detail how surface magnetic activity correlates with stellar age and spectral type. In addition to Kepler work, we have harnessed the power of the world's largest infrared interferometer to “directly” image the spotted surfaces of a few of the closest RS CVn systems, allowing a comparison of contemporaneous Doppler and light-curve inversion imaging techniques.
The current study examined the impact of television and Internet food advertising on Australian parents and children.
Parents and their children aged 8 to 14 years were exposed to a television advertisement, an Internet advertisement or a control picture for four commonly advertised energy-dense, nutrient-poor foods.
Online web panel survey, Australia.
Parents (n 1302) and their children aged 8 to 14 years (n 1302).
After a single exposure to each advertisement, parent respondents in the two exposure conditions evaluated the products more favourably, had a greater desire to consume the products and thought the product could be consumed more frequently than those in the control condition. Similar trends were observed among children, although the differences were statistically significant only for the frequency of food consumption in the Internet advertisement condition and the evaluation of one product.
The results have implications for assumptions of adults’ immunity to advertising. This is of particular importance in efforts to address child obesity and the reliance on parents to mediate the effects of food advertising.
Tells famously capture the historical sequences of the earliest farmers—but digging them is not easy. With a depth of strata of 17m at Dikili Tash, the earliest occupation was out of reach of a trench. But our researchers got there by coring, extending the date of the first occupation back 1000 years, and deducing, from small samples, the changing environment and possible connections with Anatolia.
The Russian School Twin Registry (RSTR) was established in 2012, supported by a grant from the Government of the Russian Federation. The main aim of the registry is to contribute to Progress in Education through Gene-Environment Studies (PROGRESS). The formation of the registry is ongoing and it is expected that most schools in the Russian Federation (approximately 50,000 schools) will contribute data to the registry. With a total of 13.7 million students in Grades 1–11 (ages 7–18), the potential number of twin pairs exceeds 100,000. Apart from the large sample size and its representative nature, the RSTR has one unique feature: in collaboration with the International Advisory Committee to the Registry, genetically sensitive cross-cultural investigations are planned, aided by the use of the common assessment instruments. Other strengths of the registry include the assessment of a large sample of non-twin school children, including those studying in the same classes as the twins in the registry. It is hoped that the RSTR will provide an important research platform for national and international educationally relevant research.
Forced chemical mixing during severe plastic deformation was investigated at Cu-Nb face-centered-cubic (fcc)/body-centered-cubic (bcc) interfaces using molecular-dynamics simulations. Three Cu-Nb interfaces were considered, with either Kurdjumov-Sachs or Nishiyama-Wassermann orientation relationship (OR) between fcc and bcc phases. Forced mixing of a spherical bcc-Nb precipitate in fcc-Cu was also studied for comparison. Deformation was imposed by shape-preserving cycles using two different modes, biaxial compression and biplanar shearing to investigate the effects of strain path. For biplanar shear, the chemical mixing rate is strongly dependent on structure of the interface, with the Kurdjumov-Sachs OR and a (111)Cu‖(110)Nb habit plane being particularly resistant to mixing. During compression, no such dependence was found. Influences of interface diffuseness and roughness on stability were also investigated. The simulations show the interface mixing is inversely related to interface shear strength during shear deformation, but dominated by dislocation-glide through the Cu phase and subsequent absorption at Cu-Nb interfaces during compression deformation.
Extreme impacts can result from extreme weather and climate events, but can also occur without extreme events. This chapter examines two broad categories of impacts on human and ecological systems, both of which are influenced by changes in climate, vulnerability, and exposure: first, the chapter primarily focuses on impacts that result from extreme weather and climate events, and second, it also considers extreme impacts that are triggered by less-than-extreme weather or climate events. These two categories of impacts are examined across sectors, systems, and regions. Extreme events can have positive as well as negative impacts on ecosystems and human activities.
Economic losses from weather- and climate-related disasters have increased, but with large spatial and interannual variability (high confidence, based on high agreement, medium evidence). Global weather- and climate-related disaster losses reported over the last few decades reflect mainly monetized direct damages to assets, and are unequally distributed. Estimates of annual losses have ranged since 1980 from a few US$ billion to above 200 billion (in 2010 dollars), with the highest value for 2005 (the year of Hurricane Katrina). In the period 2000 to 2008, Asia experienced the highest number of weather- and climate-related disasters. The Americas suffered the most economic loss, accounting for the highest proportion (54.6%) of total loss, followed by Asia (27.5%) and Europe (15.9%). Africa accounted for only 0.6% of global economic losses. Loss estimates are lower bound estimates because many impacts, such as loss of human lives, cultural heritage, and ecosystem services, are difficult to value and monetize, and thus they are poorly reflected in estimates of losses. [4.5.1, 18.104.22.168, 22.214.171.124]