Bandstructure approach to near edge structure

We review the current state of the art in EELS fingerprinting by computer simulation, focusing on the bandstructure approach to the problem. Currently calculations are made using a one electron theory, but we describe in principle the way to go beyond this to include final state effects. We include these effects within the one electron framework using the Slater transition state formula and assess the errors involved. Two examples are then given which illustrate the use of the one electron approximation within density functional theory. Our approach is to combine predicted atomic structure with predicted electronic structure to assist in fingerprinting of complex crystal structures.

Electron energy-loss near-edge shape as a probe to investigate the stabilization of yttria-stabilized zirconia

The electron energy-loss near-edge structure (ELNES) at the O K edge has been studied in yttria-stabilized zirconia (YSZ). The electronic structure of YSZ for compositions between 3 and 15 mol % Y2O3 has been computed using a pseudopotential-based technique to calculate the local relaxations near the O vacancies. The results showed phase transition from the tetragonal to cubic YSZ at 10 mol % of Y2O3, reproducing experimental observations. Using the relaxed defect geometry, calculation of the ELNES was carried out using the full-potential linear muffin-tin orbital method. The results show very good agreement with the experimental O K-edge signal, demonstrating the power of using ELNES to probe the stabilization mechanism in doped metal oxides.

Water requirements as a bottleneck in the reintroduction of European roe deer to the southern edge of its range

Success rates of reintroduction programs are low, often owing to a lack of knowledge of site-specific ecological requirements. A reintroduction program of European roe deer (Capreolus capreolus (L., 1758)) in a dry Mediterranean region in Israel provides an opportunity to study the bottleneck effect of water requirements on a mesic-adapted species. Four does were hand-reared and released in a 10 ha site consisting of an early succession scrubland and a mature oak forest. We measured daily energy expenditure (DEE) and water turnover (WTO) using the doubly labeled water technique during summer and winter. DEE was similar in the summer and winter, but there was a significant difference in WTO and in the source of gained water. In winter, WTO was 3.3 L/day, of which 67% was obtained from vegetation. In summer, WTO dropped to 2.1 L/day, of which only 20% was obtained from the diet and 76% was gained from drinking. When the water source was moved to a nonpreferred habitat, drinking frequency dropped significantly, but water consumption remained constant. In a dry Mediterranean environment, availability of free water is both a physiological contraint and a behavioral constraint for roe deer. This study demonstrates the importance of physiological and behavioral feasibility studies for reintroduction programs.

Examining the presence of Arching-Action in Edge Stiffened Bridge Deck Cantilever Overhangs Subjected to a Wheel Load

Engineers have proposed the idea that there may be some arching action present in bridge deck cantilever overhangs stiffened along their longitudinal free edge, via a traffic barrier, subjected to a wheel load. This paper includes the details of a full-scale corrosion-free bridge deck with cantilever overhangs stiffened along their longitudinal free edge by a traffic barrier wall that has been constructed and tested under static and fatigue wheel loads at the University of Manitoba. It also reviews experimental test results and postulates various discussions that suggest the presence of arching-action in cantilever slab overhangs. Test results indicated static ultimate load capacities significantly greater than the ultimate capacity if the mode of failure and behavior of the cantilever overhang was completely flexural. These early results confirm and indicate the presence of arching-action resulting in a significant break-through in cantilever behavior when subjected to a wheel load. The theory to account for this arching-action is not yet developed and further research should be conducted.

The View from the Edge: The Proyecto Arqueológico Chihuahua (PAC) 1990 to 2010: An Overview

The work of the Proyecto Arqueológico Chihuahua (PAC) has played an integral role in defining the origins and characteristics of the Chihuahua culture area, also known as the Casas Grandes Regional System. PAC has developed a critical suite of radiocarbon dates for the southern zone, undertaken the first substantial investigations of the Viejo period (ca. A.D. 800textendash1200 or 1250) since the early 1960s, and added to knowledge of the southern Medio period (ca. A.D. 1250textendash1450). The project has also elucidated the chronology, settlement patterns, subsistence strategies, and technology for both periods. Results of our research indicate continuity between the Viejo period, characterized by small pithouse settlements, and the pueblo focused Medio period in the southern zone, with some poorly understood external influences from both western Mesoamerica to the south and the American Southwest to the north shaping events within the area.

Efficient edge domination in regular graphs

An induced matching of a graph G is a matching having no two edges joined by an edge. An efficient edge dominating set of G is an induced matching M such that every other edge of G is adjacent to some edge in M. We relate maximum induced matchings and efficient edge dominating sets, showing that efficient edge dominating sets are maximum induced matchings, and that maximum induced matchings on regular graphs with efficient edge dominating sets are efficient edge dominating sets. A necessary condition for the existence of efficient edge dominating sets in terms of spectra of graphs is established. We also prove that, for arbitrary fixed p ≥ 3, deciding on the existence of efficient edge dominating sets on p-regular graphs is NP-complete. © 2008 Elsevier B.V. All rights reserved.

Unusual surface and edge morphologies, sp2 to sp3 hybridized transformation and electronic damage after Ar+ ion irradiation of few-layer graphene surfaces

Roughness and defects induced on few-layer graphene (FLG) irradiated by Ar+ ions at different energies were investigated using X-ray photoemission spectroscopy (XPS) and atomic force microscopy techniques. The results provide direct experimental evidence of ripple formation, sp2 to sp3 hybridized carbon transformation, electronic damage, Ar+ implantation, unusual defects and edge reconstructions in FLG, which depend on the irradiation energy. In addition, shadowing effects similar to those found in oblique-angle growth of thin films were seen. Reliable quantification of the transition from the sp2-bonding to sp3-hybridized state as a result of Ar+ ion irradiation is achieved from the deconvolution of the XPS C (1s) peak. Although the ion irradiation effect is demonstrated through the shape of the derivative of the Auger transition C KVV spectra, we show that the D parameter values obtained from these spectra which are normally used in the literature fail to account for the sp2 to sp3 hybridization transition. In contrast to what is known, it is revealed that using ion irradiation at large FLG sample tilt angles can lead to edge reconstructions. Furthermore, FLG irradiation by low energy of 0.25 keV can be a plausible way of peeling graphene layers without the need of Joule heating reported previously

Admission Control for TCP Flows Using Packet Classes and Edge-to-edge Measurements of Aggregates

TCP flows from applications such as the web or ftp are well supported by a Guaranteed Minimum Throughput Service (GMTS), which provides a minimum network throughput to the flow and, if possible, an extra throughput. We propose a scheme for a GMTS using Admission Control (AC) that is able to provide different minimum throughput to different users and that is suitable for "standard" TCP flows. Moreover, we consider a multidomain scenario where the scheme is used in one of the domains, and we propose some mechanisms for the interconnection with neighbor domains. The whole scheme uses a small set of packet classes in a core-stateless network where each class has a different discarding priority in queues assigned to it. The AC method involves only edge nodes and uses a special probing packet flow (marked as the highest discarding priority class) that is sent continuously from ingress to egress through a path. The available throughput in the path is obtained at the egress using measurements of flow aggregates, and then it is sent back to the ingress. At the ingress each flow is detected using an implicit way and then it is admission controlled. If it is accepted, it receives the GMTS and its packets are marked as the lowest discarding priority classes; otherwise, it receives a best-effort service. The scheme is evaluated through simulation in a simple "bottleneck" topology using different traffic loads consisting of "standard" TCP flows that carry files of varying sizes

The response of the sea ice edge to atmospheric and oceanic jet formation

The sea ice edge presents a region of many feedback processes between the atmosphere, ocean, and sea ice (Maslowski et al.). Here the authors focus on the impact of on-ice atmospheric and oceanic flows at the sea ice edge. Mesoscale jet formation due to the Coriolis effect is well understood over sharp changes in surface roughness such as coastlines (Hunt et al.). This sharp change in surface roughness is experienced by the atmosphere and ocean encountering a compacted sea ice edge. This paper presents a study of a dynamic sea ice edge responding to prescribed atmospheric and oceanic jet formation. An idealized analytical model of sea ice drift is developed and compared to a sea ice climate model [the Los Alamos Sea Ice Model (CICE)] run on an idealized domain. The response of the CICE model to jet formation is tested at various resolutions. It is found that the formation of atmospheric jets at the sea ice edge increases the wind speed parallel to the sea ice edge and results in the formation of a sea ice drift jet in agreement with an observed sea ice drift jet (Johannessen et al.). The increase in ice drift speed is dependent upon the angle between the ice edge and wind and results in up to a 40% increase in ice transport along the sea ice edge. The possibility of oceanic jet formation and the resultant effect upon the sea ice edge is less conclusive. Observations and climate model data of the polar oceans have been analyzed to show areas of likely atmospheric jet formation, with the Fram Strait being of particular interest.

Are leaf-litter frogs and lizards affected by edge effects due to forest fragmentation in Brazilian Atlantic forest?

FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo