Phase formation and thermal stability of ultrathin nickel-silicides on Si(100)

The solid-state reaction and agglomeration of thin nickel-silicide films was investigated from sputter deposited nickel films (1-10 nm) on silicon-on-insulator (100) substrates. For typical anneals at a ramp rate of 3 degrees C/s, 5-10 nm Ni films react with silicon and form NiSi, which agglomerates at 550-650 degrees C, whereas films with a thickness of 3.7 nm of less were found to form an epitaxylike nickel-silicide layer. The resulting films show an increased thermal stability with a low electrical resistivity up to 800 degrees C

Slow shocks and conduction fronts from Petschek reconnection of skewed magnetic fields: two-fluid effects

In models of fast magnetic reconnection, flux transfer occurs within a small portion of a current sheet triggering stored magnetic energy to be thermalized by shocks. When the initial current sheet separates magnetic fields which are not perfectly anti-parallel, i.e. they are skewed, magnetic energy is first converted to bulk kinetic energy and then thermalized in slow magnetosonic shocks. We show that the latter resemble parallel shocks or hydrodynamic shocks for all skew angles except those very near the anti-parallel limit. As for parallel shocks, the structures of reconnection-driven slow shocks are best studied using two-fluid equations in which ions and electrons have independent temperature. Time-dependent solutions of these equations can be used to predict and understand the shocks from reconnection of skewed magnetic fields. The results differ from those found using a single-fluid model such as magnetohydrodynamics. In the two-fluid model electrons are heated indirectly and thus carry a heat flux always well below the free-streaming limit. The viscous stress of the ions is, however, typically near the fluid-treatable limit. We find that for a wide range of skew angles and small plasma beta an electron conduction front extends ahead of the slow shock but remains within the outflow jet. In such cases conduction will play a more limited role in driving chromospheric evaporation than has been predicted based on single-fluid, anti-parallel models

Thermal performance of two heat exchangers for thermoelectric generators

Thermal performance of heat exchanger is important for potential application in integrated solar cell/module and thermoelectric generator (TEG) system. Usually, thermal performance of a heat exchanger for TEGs is analysed by using a 1D heat conduction theory which ignores the detailed phenomena associated with thermo-hydraulics. In this paper, thermal and mass transports in two different exchangers are simulated by means of a steady-state, 3D turbulent flow k -e model with a heat conduction module under various flow rates. In order to simulate an actual working situation of the heat exchangers, hot block with an electric heater is included in the model. TEG model is simplified by using a 1D heat conduction theory, so its thermal performance is equivalent to a real TEG. Natural convection effect on the outside surfaces of the computational model is considered. Computational models and methods used are validated under transient thermal and electrical experimental conditions of a TEG. It is turned out that the two heat exchangers designed have a better thermal performance compared with an existing heat exchanger for TEGs, and more importantly, the fin heat exchanger is more compact and has nearly half temperature rise compared with the tube heat exchanger

The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts

The apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives

Response Validity in Forensic Neuropsychology: Exploratory Factor Analytic Evidence of Distinct Cognitive and Psychological Constructs

Forensic neuropsychology studies usually address either cognitive effort or psychological response validity. Whether these are distinct constructs is unclear. In 122 participants evaluated in a compensation-seeking context, the present Exploratory Factor Analysis examined whether forced-choice cognitive effort measures (Victoria Symptom Validity Test, Test of Memory Malingering, Letter Memory Test) and Minnesota Multiphasic Personality Inventory, Second Edition (MMPI-2) validity scales (L, F, K, FBS, Fp, RBS, Md, Dsr2, S) load on independent factors. Regardless of factor rotation strategy (orthogonal or oblique), four response validity factors emerged by means of both Principal Components Analysis (82.7% total variance) and Principal-Axis Factor Analysis (74.1% total variance). The four factors were designated as follows: Factor I, with large loadings from L, K, and S—underreporting of psychologicalsymptoms; Factor II, with large loadings from FBS, RBS, and Md—overreporting of neurotic symptoms; Factor III, with large loadings from VSVT, TOMM, and LMT—insufficient cognitive effort; and Factor IV, with the largest loadings from F, Fp, and Dsr2—overreporting of psychotic/rarely endorsed symptoms. Results reflect the heterogeneity of response validity in forensic samples referred for neuropsychological evaluation. Administration of both cognitive effort measures and psychological validity scales is imperative to accurate forensic neuropsychological assessment. (JINS, 2007, 13, 440–449.

Fast and slow two-fluid magnetic reconnection

We present a two-fluid magnetohydrodynamics (MHD) model of quasi-stationary, two-dimensional magnetic reconnection in an incompressible plasma composed of electrons and ions. We find two distinct regimes of slow and fast reconnection. The presence of these two regimes can provide a possible explanation for the initial slow build up and subsequent rapid release of magnetic energy frequently observed in cosmic and laboratory plasmas.Comment: 16 pages, 2 figures, 1 tabl

Airborne Fine Particulate Matter (PM-10) in Southeast Chicago

published or submitted for publicationis peer reviewedOpe

Effective dynamics using conditional expectations

The question of coarse-graining is ubiquitous in molecular dynamics. In this article, we are interested in deriving effective properties for the dynamics of a coarse-grained variable $\xi(x)$, where $x$ describes the configuration of the system in a high-dimensional space $\R^n$, and $\xi$ is a smooth function with value in $\R$ (typically a reaction coordinate). It is well known that, given a Boltzmann-Gibbs distribution on $x \in \R^n$, the equilibrium properties on $\xi(x)$ are completely determined by the free energy. On the other hand, the question of the effective dynamics on $\xi(x)$ is much more difficult to address. Starting from an overdamped Langevin equation on $x \in \R^n$, we propose an effective dynamics for $\xi(x) \in \R$ using conditional expectations. Using entropy methods, we give sufficient conditions for the time marginals of the effective dynamics to be close to the original ones. We check numerically on some toy examples that these sufficient conditions yield an effective dynamics which accurately reproduces the residence times in the potential energy wells. We also discuss the accuracy of the effective dynamics in a pathwise sense, and the relevance of the free energy to build a coarse-grained dynamics

Microbiome Engineering: A Promising Approach to Improve Coral Health

The world’s coral reefs are threatened by the cumulative impacts of global climate change and local stressors. Driven largely by a desire to understand the interactions between corals and their symbiotic microorganisms, and to use this knowledge to eventually improve coral health, interest in coral microbiology and the coral microbiome has increased in recent years. In this review, we summarize the role of the coral microbiome in maintaining a healthy metaorganism by providing nutrients, support for growth and development, protection against pathogens, and mitigation of environmental stressors. We explore the concept of coral microbiome engineering, that is, precise and controlled manipulation of the coral microbiome to aid and enhance coral resilience and tolerance in the changing oceans. Although coral microbiome engineering is clearly in its infancy, several recent breakthroughs indicate that such engineering is an effective tool for restoration and preservation of these valuable ecosystems. To assist with identifying future research targets, we have reviewed the common principles of microbiome engineering and its applications in improving human health and agricultural productivity, drawing parallels to where coral microbiome engineering can advance in the not-too-distant future. Finally, we end by discussing the challenges faced by researchers and practitioners in the application of microbiome engineering in coral reefs and provide recommendations for future work