Hyperfine Interactions in Antiferromagnetic EuTe using the Te-125 Mossbauer Resonance

Europium telluride crystallizes in the NaCl structure and is antiferromagnetic with a Néel temperature TN of 9.6 K. We have used the 35.5 keV Møssbauer transition in Te-125 to examine the nature of the spontaneous magnetic moment which has been observed in conducting samples below TN. At 80 K the Mössbauer resonance spectrum consisted of a single absorption line comparable in width with the spectrum of nonmagnetic cubic ZnTe, indicating the absence of a significant quadrupole splitting at this temperature. At 4.2 K the line-width increased by a factor of 1.5, which is equivalent to a single magnetic hyperfine field at the Te sites of about 73 kOe. The line showed gradual broadening with increasing external longitudinal magnetic field up to 70 kOe at 4.2 K. These observations are consistent with the magnetization measurements as well as with recent spin-echo NMR experiments showing resonances which may be attributed to Te-125. We conclude from the shape of the Mössbauer line that the broadening observed at 4.2 K is most likely due to a single magnetic hyperfine field of magnitude 73 kOe acting at the Te sites. An applied magnetic field Hsite, but near the canted to paramagnetic transition (H≈66 kOe at 4.2 K) the observed hyperfine field increases more rapidly with H, reaching a value of 112 kOe when H=70 kOe

Toward a New Normal: Trauma, Diversity, and the New Orleans Urban Long-Term Research Area Exploratory (ULTRA-Ex) Project

Though it is widely held that social-ecological diversity is critical for resilience and the recovery of post-trauma urban systems, there is disagreement over issues of causes and impacts. In this paper, we present analysis and findings of the impact of trauma on patterns of social-ecological diversity in New Orleans in the years following the Hurricane Katrina disaster (August-September 2005). We first provide an overview of conceptualizations of trauma and urban ecosystem resilience, and discuss programmatic research questions and objectives. We then examine city-wide land use / land cover change, showing that flood trauma reduced landscape-level ecological diversity across New Orleans. By reconstructing archival biotic surveys of indicator organisms, we also show that many ecological communities within New Orleans experienced an acute decline, followed by recovery over time. Census-based analyses indicate that ethno-racial diversity also increased over time. Unlike pre-Katrina conditions, ethno-racial and landscape-level ecological diversity were negatively correlated after the disaster as a consequence of contrasting responses to flooding. Our analyses and findings highlight the complexity and challenges of conceptualizing, operationalizing, and measuring social-ecological diversity and related processes of resilience

Shapes, marbles and pebbles: template-based content creation for location-based games

This paper presents the TOTEM framework for supporting the content creation and structuring for location-based games. Shapes (templates), Marbles (instances) and Pebbles (raw data) build the conceptual background while two integrated tools support the overall workflow: TOTEM.Designer, a web-application that allows for desktop-based authoring and TOTEM.Scout, a mobile app that allows for in-situ authoring. The TOTEM framework supports different user roles and allows inexperienced users to collect and create content. All data can be exported and easily added to external games

Rotary engine cooling system

A rotary engine has a substantially trochoidal-shaped housing cavity in which a rotor planetates. A cooling system for the engine directs coolant along a single series path consisting of series connected groups of passages. Coolant enters near the intake port, passes downwardly and axially through the cooler regions of the engine, then passes upwardly and axially through the hotter regions. By first flowing through the coolest regions, coolant pressure is reduced, thus reducing the saturation temperature of the coolant and thereby enhancing the nucleate boiling heat transfer mechanism which predominates in the high heat flux region of the engine during high power level operation