bluuebunny/crossref_metadata_2025 huggingface dataset:
Weak Cayley tables and generalized centralizer rings of finite groups
Authors: HUMPHRIES STEPHEN P. , RODE EMMA L.
Published: August 2012

For a finite groupGwe study certain rings(k)Gcalledk-S-rings, one for eachk≥ 1, where(1)Gis the centraliser ringZ(ℂG) ofG. These rings have the property that(k+1)Gdetermines(k)Gfor allk≥ 1. We study the relationship of(2)Gwith the weak Cayley table ofG. We show that(2)Gand the weak Cayley table together determine the sizes of the derived factors ofG(noting that a result of Mattarei shows that(1)G=Z(ℂG) does not). We also show that(4)GdeterminesGfor any groupGwith finite conjugacy classes, thus giving an answer to a question of Brauer. We give a criteria for two groups to have the same 2-S-ring and a result guaranteeing that two groups have the same weak Cayley table. Using these results we find a pair of groups of order 512 that have the same weak Cayley table, are a Brauer pair, and have the same 2-S-ring.
Research on encouraging sketching in engineering design
Authors: Schmidt Linda C. , Hernandez Noe Vargas , Ruocco Ashley L.
Published: August 2012

The value of sketching in engineering design has been widely documented. This paper reviews trends in recent studies on sketching in engineering design and focuses on the encouragement of sketching. The authors present three experimental studies on sketching that look at (1) sketching assignments and their motivation, (2) the impact of a sketching lesson, and (3) the use of Smartpen technology to record sketching; overall these studies address the research question: Can sketching frequency be influenced in engineering education? Influencing sketching frequency is accomplished through motivation, learning, and use of technology for sketching, respectively. Results indicate that these three elements contribute to the encouragement of sketching in engineering design.
RATA.Gesture: A gesture recognizer developed using data mining
Authors: Chang Samuel Hsiao-Heng , Blagojevic Rachel , Plimmer Beryl
Published: August 2012

Although many approaches to digital ink recognition have been proposed, most lack the flexibility and adaptability to provide acceptable recognition rates across a variety of problem spaces. This project uses a systematic approach of data mining analysis to build a gesture recognizer for sketched diagrams. A wide range of algorithms was tested, and those with the best performance were chosen for further tuning and analysis. Our resulting recognizer, RATA.Gesture, is an ensemble of four algorithms. We evaluated it against four popular gesture recognizers with three data sets; one of our own and two from other projects. Except for recognizer–data set pairs (e.g., PaleoSketch recognizer and PaleoSketch data set) the results show that it outperforms the other recognizers. This demonstrates the potential of this approach to produce flexible and accurate recognizers.
Systematic abstraction of abstract machines
Authors: VAN HORN DAVID , MIGHT MATTHEW
Published: August 2012

We describe a derivational approach to abstract interpretation that yields novel and transparently sound static analyses when applied to well-established abstract machines for higher-order and imperative programming languages. To demonstrate the technique and support our claim, we transform the CEK machine of Felleisen and Friedman (Proc. of the 14th ACM SIGACT-SIGPLAN Symp. Prin. Program. Langs, 1987, pp. 314–325), a lazy variant of Krivine's machine (Higher-Order Symb. Comput. Vol 20, 2007, pp. 199–207), and the stack-inspecting CM machine of Clements and Felleisen (ACM Trans. Program. Lang. Syst. Vol 26, 2004, pp. 1029–1052) into abstract interpretations of themselves. The resulting analyses bound temporal ordering of program events; predict return-flow and stack-inspection behavior; and approximate the flow and evaluation of by-need parameters. For all of these machines, we find that a series of well-known concrete machine refactorings, plus a technique of store-allocated continuations, leads to machines that abstract into static analyses simply by bounding their stores. These machines are parameterized by allocation functions that tune performance and precision and substantially expand the space of analyses that this framework can represent. We demonstrate that the technique scales up uniformly to allow static analysis of realistic language features, including tail calls, conditionals, mutation, exceptions, first-class continuations, and even garbage collection. In order to close the gap between formalism and implementation, we provide translations of the mathematics as running Haskell code for the initial development of our method.
Every bit counts: The binary representation of typed data and programs
Authors: KENNEDY ANDREW J. , VYTINIOTIS DIMITRIOS
Published: August 2012

We show how the binary encoding and decoding of typed data and typed programs can be understood, programmed and verified with the help of question–answer games. The encoding of a value is determined by the yes/no answers to a sequence of questions about that value; conversely, decoding is the interpretation of binary data as answers to the same question scheme. We introduce a general framework for writing and verifying game-based codecs. We present games in Haskell for structured, recursive, polymorphic and indexed types, building up to a representation of well-typed terms in the simply-typed λ-calculus with polymorphic constants. The framework makes novel use of isomorphisms between types in the definition of games. The definition of isomorphisms together with additional simple properties make it easy to prove that codecs derived from games never encode two distinct values using the same code, never decode two codes to the same value and interpret any bit sequence as a valid code for a value or as a prefix of a valid code. Formal properties of the framework have been proved using the Coq proof assistant.
Fortifying macros
Authors: CULPEPPER RYAN
Published: August 2012

Existing macro systems force programmers to make a choice between clarity of specification and robustness. If they choose clarity, they must forgo validating significant parts of the specification and thus produce low-quality language extensions. If they choose robustness, they must write in a style that mingles the implementation with the specification and therefore obscures the latter. This paper introduces a new language for writing macros. With the new macro system, programmers naturally write robust language extensions using easy-to-understand specifications. The system translates these specifications into validators that detect misuses—including violations of context-sensitive constraints—and automatically synthesize appropriate feedback, eliminating the need for ad hoc validation code.
Developmental competence of ovine oocyte following vitrification: effect of oocyte developmental stage, cumulus cells, cytoskeleton stabiliser, FBS concentration, and equilibration time
Authors: Shirazi Abolfazl , Taheri Fatemeh , Nazari Hassan , Norbakhsh-nia Maryam , Ahmadi Ebrahim , Heidari Banafsheh
Published: August 2012

The aim of the present study was to examine the effects of fetal bovine serum (FBS) concentration, equilibration time, and oocyte pre-treatment with cytochalasin B (CCB) on subsequent development of vitrified-warmed ovine immature (GVCOCs) and matured (MII) oocytes with (MIICOCs) or without cumulus cells (MIIDOs). In Experiment 1, the effects of FBS concentrations (10 and 20%) during the vitrification-warming procedure were examined. Survival rates after warming were not different between GVCOCs, MIICOCs and MIIDOs oocytes. After in vitro fertilization, rate of cleaved embryos in MIICOCs group at the presence of 20%FBS was higher than MIIDOs and GVCOCs groups. In Experiment 2, the effects of equilibration times (5, 7, and 10 min) were examined. There was no difference in survival rate of vitrified-warmed oocytes equilibrated at different times. Although, the rate of cleavage in MIICOCs and MIIDOs oocytes equilibrated for 10 and 7 min, respectively, was higher than 5 min equilibrated MIIDOs and 7 and 10 min equilibrated GVCOCs oocytes. In Experiment 3, the effects of oocyte pre-treatment with CCB were examined. Despite the insignificant difference in survival rate of vitrified-warmed ovine immature and matured oocytes, the rates of cleavage in CCB pretreated groups were significantly lower than untreated groups. Moreover, the blastocysts were only derived from those cumulus enclosed vitrified-warmed germinal vesicle (GV) and MII oocytes that had been exposed to 10% FBS in the absence of CCB. In conclusion, the presence of cumulus cells, 10% FBS, and the omission of CCB were beneficial for post-warming development of vitrified ovine oocytes.
Distribution and palaeoecology of Ordovician bivalves and gastropods from Girvan, SW Scotland
Authors: Stewart Sarah E.
Published: August 2012

Molluscs from the Middle and Upper Ordovician succession of Girvan, SW Scotland are common and diverse in some localities. The mollusc fauna consists mainly of gastropods, bivalves and various univalved molluscs (mimospirids and tergomyans), along with scarcer polyplacophorans, rostroconchs and cephalopods. The present study gives an overview of the distribution and palaeoecology of bivalves, gastropods and univalved molluscs and compares them with mollusc faunas worldwide. Gastropods, mimospirids and tergomyans are present from the Darriwilian (mid Llanvirn) onwards in both siliciclastic and carbonate facies, and increase in diversity through the Sandbian (Caradoc) and into the Katian (Ashgill). Bivalves first appeared in Girvan in the late Darriwilian (early Caradoc) in deep water siliciclastic facies; where they continued to be more abundant and diverse than in equivalent carbonate facies. Molluscs are initially Laurentian in aspect, though peri-Gondwanan faunal elements occur, particularly during the Sandbian. The pattern of bivalve and gastropod diversity found in the Ordovician of Girvan generally follows that of the known global diversity for these groups.
Applying luminescence methods to geoarchaeology: a case study from Stronsay, Orkney
Authors: Kinnaird Tim C. , Sanderson David C. W. , Woodward Naomi L.
Published: August 2012

Luminescence methods were used to date a palaeoenvironmental coastal exposure on Stronsay, Orkney. The section consists of glacial sediments that are overlain by intercalated peats and windblown sands, implying varying past environmental conditions. Rapid luminescence characterisation was undertaken using screening methods in combination with quantitative dating of selected samples, providing information on depositional processes and chronology. A temporal discontinuity between the glacial sediments and later peats encompasses the period associated with an important Mesolithic site located inland, and implies erosional episodes. The onset of blanket bog formation on Stronsay dates to 3760±330 yrs BP, consistent with observations elsewhere in Orkney and northern Scotland. Periods of enhanced aeolian activity on Stronsay occurred in the late Bronze Age (2700±265 yrs BP) and at the beginning of the Little Ice Age (650±75 yrs BP). Recent periods of sand deposition in the 19th and 20th centuries (AD 1865±20 and 1960±5) correspond to periods of known historic storminess. These results add to an expanding catalogue of data on sand movements throughout the Holocene in Orkney, and set a framework to interpret the evolution of nearby archaeological and natural landscapes from prehistoric to modern times.
The legal framework of humanitarian access in armed conflict
Authors: Schwendimann Felix
Published: August 2012

Obtaining and maintaining humanitarian access to populations in need by humanitarian actors is a challenge. A wide range of constraints on humanitarian access exist, including ongoing hostilities or an otherwise insecure environment, destruction of infrastructure, often onerous bureaucratic requirements, and attempts by parties to armed conflict to block access intentionally. The difficulties that these constraints present to humanitarians are frequently compounded by a lack of familiarity – on the part of states, non-state armed groups, and humanitarian relief organizations – with the legal framework. The main purpose of this article is to lay out the existing international legal framework regulating humanitarian access in situations of armed conflict.
Zur Rolle und Bedeutung künstlerischer Gemeinschaftsarbeiten
Authors: Richter-Reichenbach Karin-Sophie
Published: August 2012

Zusammenfassung. Soll Therapie gelingen, so setzt sie eine gegenseitig vertrauende und respektierende Atmosphäre voraus, die zugleich aktiviert und arbeitsmotovierend zu wirken imstande ist. Langjährige eigene Erfahrungen zeigen, dass künstlerische Gemeinschaftsarbeiten in den verschiedensten alters- und herkunftsheterogenen Gruppen eben dies leisten. Der nachfolgende Aufsatz will dies exemplarisch an einem universitären Seminar mit Psychologiestudenten zeigen, ein Klientel, das mir bislang fremd war. Ein Ziel neben den oben genannten war es, diesem Klientel die Erfahrung zu vermitteln, dass und welch hohe Öffner-Funktion einer ganzheitlichen kreativen Arbeit zukommt. Gleichzeitig sollte ein Einblick in die Theorie und Praxis der von mir vertretenen ‚Pädagogischen Kunsttherapie’ gegeben werden. Medienwechsel wurde praktiziert, um einerseits Einblick in die infrage kommenden verschiedensten Künstlerischen Medien zu geben und andererseits an vorhandene Vorlieben Einzelner anzuknüpfen.
Entwicklung der kurzen strukturierten Kunsttherapie, KSKT®, einer ressourcenorientierten Kurzzeitintervention in der Psycho-Onkologie
Authors: Hopf Alexandra
Published: August 2012

Zusammenfassung. In einer onkologischen Akutklinik unterziehen sich Krebspatienten unterschiedlichen Therapien zur Behandlung ihrer Erkrankungen. Patienten, die psycho-onkologische Unterstützung in Anspruch nehmen, formulierten häufig Verunsicherung und Angst. Diese zeigen sich in Bezug auf ihre Selbstwahrnehmung, auf den Erfolg der Therapien, im Hinblick auf Belastungen und Veränderungen ihrer sozialen, ihrer materiellen Situation und in Bezug auf ihre bisherigen Rollen in Gesellschaft und Familie. Die Methode der kurzen strukturierten Kunsttherapie (KSKT®) ist spontan aus einer alltäglichen Betreuungssituation mit einer an Krebs erkrankten Patientin entstanden. Diese Patientin thematisierte Aspekte, die in eine Gestaltung einfließen können sollten und die dennoch gestaltbar bleiben sollte. Beziehungen und Ressourcen werden als flexible Bildteile repräsentiert. Die Collage als bildnerische Technik bot hier entsprechende Eigenschaften an. Collagenartiges Zusammensetzen einzelner, zuvor gefertigter Bildteile ermöglichte diese Flexibilität und bot genügend Spielraum für die Patientin. 1 Die genaue Beschreibung der einzelnen Arbeitsschritte der KSKT® folgen im Text. Das strukturierte Interventionsmanual zur KSKT® bietet Struktur um Patienten generell in existenziell verunsichernden Lebenssituationen ausreichend zu stabilisieren.
Nanoscale lignin particles as sources of dissolved iron to the ocean
Authors: Krachler Regina , von der Kammer Frank , Jirsa Franz , Süphandag Altan , Krachler Rudolf F. , Plessl Christof , Vogt Margret , Keppler Bernhard K. , Hofmann Thilo
Published: August 2012

Primary production in large areas of the open ocean is limited by low iron concentrations. Rivers are potential sources of iron to the ocean, however, riverine iron is prone to intense flocculation and sedimentation in the estuarine mixing zone. Here we report the detection of iron‐rich nanoparticles in a typical peatland‐draining creek which are resistant against salt‐induced flocculation i.e., their behavior is in sharp contrast to the well‐known behavior of Fe colloids in river waters. Sample fractionation by AsFlFFF (Asymmetric Flow Field Flow Fractionation) revealed that these powerful iron carriers are in the size range of only 0.5–3.0 nm hydrodynamic diameter. They were isolated from the water phase using solid phase extraction/gel permeation chromatography, and analyzed by a CuO oxidation/GC‐MS method. Our results suggest that the particles consist mainly of lignin catabolites and that gymnosperm as well as angiosperm tissues are contributors to the seawater‐resistant iron‐bearing DOM. Lignin phenols, which have no autochthonous source in the ocean, have been nevertheless found in low concentrations throughout the entire Arctic, Atlantic, and Pacific oceans. It is therefore tempting to speculate that peatland‐derived iron‐bearing lignin particles may have a sufficiently long half‐life in ocean waters to sustain iron concentration in extended regions of the ocean.
Three‐dimensional surface displacements and rotations from differencing pre‐ and post‐earthquake LiDAR point clouds
Authors: Nissen Edwin , Krishnan Aravindhan K. , Arrowsmith J. Ramón , Saripalli Srikanth
Published: August 2012

The recent explosion in sub‐meter resolution airborne LiDAR data raises the possibility of mapping detailed changes to Earth's topography. We present a new method that determines three‐dimensional (3‐D) coseismic surface displacements and rotations from differencing pre‐ and post‐earthquake airborne LiDAR point clouds using the Iterative Closest Point (ICP) algorithm. Tested on simulated earthquake displacements added to real LiDAR data along the San Andreas Fault, the method reproduces the input deformation for a grid size of ∼50 m with horizontal and vertical accuracies of ∼20 cm and ∼4 cm, values that mimic errors in the original spot height measurements. The technique also measures rotations directly, resolving the detailed kinematics of distributed zones of faulting where block rotations are common. By capturing near‐fault deformation in 3‐D, the method offers new constraints on shallow fault slip and rupture zone deformation, in turn aiding research into fault zone rheology and long‐term earthquake repeatability.
Changes in orographic precipitation patterns caused by a shift from snow to rain
Authors: Pavelsky Tamlin M. , Sobolowski Stefan , Kapnick Sarah B. , Barnes Jason B.
Published: August 2012

Climate warming will likely cause a shift from snow to rain in midlatitude mountains. Because rain falls faster than snow, it is not advected as far by prevailing winds before reaching the ground. A shift in precipitation phase thus may alter precipitation patterns. Using the Weather Research and Forecasting (WRF) regional climate model at 27‐9‐3 km resolutions over the California Sierra Nevada, we conducted an idealized experiment consisting of a present climate control run and two additional simulations in which (a) fall speed for snow is similar to rain and (b) all precipitation is constrained to fall as liquid. Rather than simulating future climates directly, these perturbation experiments allow us to test the potential impacts of changing precipitation phase in isolation from other factors such as variable large‐scale atmospheric circulation. Relative to the control, both perturbations result in a rain shadow deepened by ∼30–60%, with increased focusing of precipitation on the western Sierra Nevada slopes best resolved at ≤9 km resolutions. Our results suggest that altered precipitation phase associated with climate change will likely affect spatial distributions of water resources, floods, and landslides in the Sierra Nevada and similar midlatitude mountain ranges.
Stress state estimation by geophysical logs in NanTroSEIZE Expedition 319‐Site C0009, Kumano Basin, southwest Japan
Authors: Wu Hung‐Yu , Kinoshita Masataka , Sanada Yoshinori
Published: August 2012

To understand the stress regime in the shallow portion of the Nankai Trough seismogenic zone, we carefully investigated the resistivity image logs at IODP Site C0009 that penetrated to 1600 meters below the sea floor (mbsf) in the central Kumano forearc basin. During the riser drilling, several downhole measurements were run including image logs, caliper and comprehensive geophysical logs sets. Borehole resistivity images obtained by a wireline‐logging tool were reprocessed in order to eliminate image artifacts generated by sticky tool movements, etc. The constraints on the possible magnitude and orientation of horizontal principal stresses are provided from the borehole images, rock strength, and logging data. The absence of borehole breakouts above 1285 mbsf represents a small difference (<10 MPa) between horizontal principal stresses and reflects the normal faulting and strike–slip faulting stress regimes. A stable, continuous breakout was observed in the resistivity image logs suggest that the stress state is in a strike–slip faulting and tending to reverse faulting regime below 1285 mbsf. The differential horizontal stress (up to 15 MPa) is significantly larger than in the shallow portion of the borehole (SHAMX ≫ Sv > Shmin).
Static stress interactions in extensional earthquake sequences: An example from the South Lunggar Rift, Tibet
Authors: Ryder Isabelle , Bürgmann Roland , Fielding Eric
Published: August 2012

An extensional earthquake sequence occurred in 2004–8 across a graben in the South Lunggar Rift on the Tibetan Plateau. We use InSAR data to determine the location, fault geometry and slip distribution of these earthquakes and to test whether the sequence is compatible with static stress triggering. The Mw 6.2 and 6.3 earthquakes in 2004 and 2005 both ruptured west‐dipping faults on the east side of a graben. In 2008, a Mw 6.7 earthquake ruptured a pair of east‐dipping fault segments on the other side of the graben, offset from the earlier ruptures. We compute first‐order dislocation models of stress change and demonstrate that the order and spatial configuration of this sequence of events is compatible with triggering by static stress transfer. A continuation of the sequence would be most likely to occur on the northern extension of the 2008 rupture, although variable slip rate along the rift may mean that the sequence has run its course. The InSAR data for the 2008 earthquake also reveal slip on a fault that cuts the graben at a highly oblique angle. We suggest that this is a release fault accommodating differential throw in the hanging wall, and associate the deformation with a Mw 6.0 aftershock. Activity on such a release fault has not been directly imaged before. The Zhongba sequence is one of several examples of recent clustered normal‐fault earthquakes on the Plateau, and may be an example of phase‐locking of similar faults.
Impact of tropical cyclones on the ocean heat budget in the Bay of Bengal during 1999: 1. Model configuration and evaluation
Authors: Wang Jih‐Wang , Han Weiqing , Sriver Ryan L.
Published: August 2012

The impacts of two consecutive, strong tropical cyclones (TCs) – 04B (10/15–10/19) and 05B (10/25–11/3) in 1999 (hereafter, TC1 and TC2) – on the upper ocean temperature and surface height of the Bay of Bengal (BoB) are examined using the Hybrid Coordinate Ocean Model (HYCOM). The HYCOM control run is driven by the Cross‐Calibrated MultiPlatform (CCMP) satellite winds, European Center for Medium‐Range Weather Forecasts Re‐analysis Interim (ERAI) surface reanalysis data, and Tropical Rainfall Measuring Mission precipitation. In order to investigate ocean response to high wind conditions, which are not well resolved by the CCMP or ERAI products, a modified Rankine vortex is adopted to reconstruct the TC winds in an experimental run. Wind stress is determined from wind speed when considering the level‐off and decline of drag coefficient at wind speed of 34 m/s and greater. The experimental run reproduces the strong SST reduction (∼−3°C) near the Orissa seashore along and on the right of the TC tracks. TC2 (category 5) cools the BoB SST less than TC1 (category 4) likely due to the initial SST depression by TC1. TC2 has higher winds and lingers over the ocean longer than TC1, and hence the onshore Ekman transport and mass convergence induced by TC2 wind is more prominent. The HYCOM mixed layer temperatures and depths to the south of the BoB generally agree with the observations very well. The simulations, however, have weaker vertical temperature gradient in the thermocline layer, suggesting that HYCOM produces a more diffusive thermocline than the observations.
Long‐term trends in nitrogen oxide emissions from motor vehicles at national, state, and air basin scales
Authors: McDonald Brian C. , Dallmann Timothy R. , Martin Elliot W. , Harley Robert A.
Published: August 2012

A fuel‐based approach is used to estimate nitrogen oxides (NOx = NO + NO2) emissions from gasoline‐ and diesel‐powered motor vehicles. Estimates are made at the national level for the period 1990–2010. Vehicle emissions are also estimated at the state level for California, and for the South Coast (Los Angeles) and San Joaquin Valley air basins. Fuel‐based emission estimates are compared with predictions from widely used emission inventory models. Changes in diesel NOxemissions vary over time: increasing between 1990 and 1997, stable between 1997 and 2007, and decreasing since 2007. In contrast, gasoline engine‐related NOxemissions have decreased steadily, by ∼65% overall between 1990 and 2010, except in the San Joaquin Valley, where reductions were not as large due to faster population growth. In the San Joaquin Valley, diesel engines were the dominant on‐road NOxsource in all years considered (reaching ∼70% in 2010). In the urbanized South Coast air basin, gasoline engine emissions dominated in the past and have been comparable to on‐road diesel sources since 2007 (down from ∼75% in 1990). Other major anthropogenic sources of NOxare added to compare emission trends with trends in surface pollutant observations and satellite‐derived data. When all major anthropogenic NOx sources are included, the overall emission trend is downward in all cases (−45% to −60%). Future reductions in motor vehicle NOxwill depend on the effectiveness of new exhaust after‐treatment controls on heavy‐duty trucks, as well as further improvements todurabilityof emission control systems on light‐duty vehicles.
Pleistocene equatorial Pacific dynamics inferred from the zonal asymmetry in sedimentary nitrogen isotopes
Authors: Rafter Patrick A. , Charles Christopher D.
Published: August 2012

There is little agreement among models in predicting the average state of the tropical Pacific when subjected to enhanced greenhouse gas forcing. This uncertainty emphasizes the importance of reconstructing past variability in tropical Pacific climate through episodes of significant and estimable radiative forcing. Thus far, efforts along these lines have concentrated primarily on inferences of sea surface temperature variability from deep‐sea sediments. Here we offer a different view of the equatorial Pacific over the past ∼1.2 million years (Myr)—before and after the mid‐Pleistocene shift in the structure of ice ages. The zonal gradient in the nitrogen isotopic composition of sediment across the equatorial Pacific reflects nutrient delivery to the surface and, by extension, ocean dynamical properties. Over the last ∼1.2 Myr, the variability of eastern equatorial Pacific nutrient upwelling (inferred from relative nitrate utilization) was highly correlated with local seasonal insolation. By contrast, nitrate utilization was insensitive to the 100,000 year cycle that dominated many other aspects of the Pleistocene ice ages, including greenhouse gas concentrations. A strong linear relationship between relative nitrate utilization and seasonal insolation over the past ∼1 million years suggests a predictable response of one primary determinant of tropical Pacific climate change.
Altered Neurochemical Profile after Traumatic Brain Injury: 1H-MRS Biomarkers of Pathological Mechanisms
Authors: Harris Janna L , Yeh Hung-Wen , Choi In-Young , Lee Phil , Berman Nancy E , Swerdlow Russell H , Craciunas Sorin C , Brooks William M
Published: August 2012

Specific neurochemicals measured with proton magnetic resonance spectroscopy (1H-MRS) may serve as biomarkers of pathological mechanism in the brain. We used high field in vivo1H-MRS to measure a detailed neurochemical profile after experimental traumatic brain injury (TBI) in rats. We characterized neurochemical changes in the contused cortex and the normal-appearing perilesional hippocampus over a time course from 1 hour to 2 weeks after injury. We found significant changes in 19 out of 20 neurochemicals in the cortex, and 9 out of 20 neurochemicals in the hippocampus. These changes provide evidence of altered cellular metabolic status after TBI, with specific compounds proposed to reflect edema, excitotoxicity, neuronal and glial integrity, mitochondrial status and bioenergetics, oxidative stress, inflammation, and cell membrane disruption. Our results support the utility of 1H-MRS for monitoring cellular mechanisms of TBI pathology in animal models, and the potential of this approach for preclinical evaluation of novel therapies.
Kosten einer leitliniengerechten Versorgung von Hepatitis-B-Patienten in Deutschland
Authors: Stahmeyer J. , Becker H. , Heidelberger S. , Wiebner B. , Deterding K. , Cornberg M. , Manns M.-P. , Krauth C. , Wedemeyer H.
Published: August 2012

Leitliniengerechte Versorgungskosten sind bisher nur für wenige Krankheiten berechnet worden. Auch für volkswirtschaftlich bedeutende Infektionserkrankungen, wie die infektiösen Hepatitiden und HIV, gibt es keine Untersuchungen. Auf der Basis der aktuellen S3-Leitlinie − Prophylaxe, Diagnostik und Therapie der Hepatitis-B-Virus-Infektion − von 2011 wurden für die Patientengruppen HBsAg-Träger, Immuntolerante und die chronischen Hepatitis-B-Patienten mit und ohne Zirrhose die Kosten für eine leitliniengerechte Basisdiagnostik, Monitoring und Therapie errechnet. Das Modell wurde auf einen Zeitraum von 5 Jahren bezogen. Bei den Untersuchungskosten fallen die virologische Diagnostik und die bildgebenden Verfahren ins Gewicht. Hauptkostenfaktor ist aber die Therapie mit Interferon oder Polymeraseinhibitoren. Auch unter der Annahme, das nur 25 % der Infizierten erfasst werden, belaufen sich die 5-Jahres-Gesamtkosten in Deutschland auf über 2,5 Mrd. €. Damit ist die chronische Hepatitis B eine Erkrankung mit hohen Versorgungskosten. Ziel einer leitliniengerechten Versorgung ist die Verhinderung der Leberzirrhose mit ihren Komplikationen sowie des Leberzellkarzinoms. Eine konsequente Schutzimpfung gegen Hepatitis B als Prophylaxe scheint unter der Betrachtung der Versorgungskosten volkswirtschaftlich rational.
Development of a YAG laser system for the edge Thomson scattering system in ITER
Authors: Hatae T. , Yatsuka E. , Hayashi T. , Yoshida H. , Ono T. , Kusama Y.
Published: August 2012

A prototype YAG laser system for the edge Thomson scattering system in ITER has been newly developed. Performance of the laser amplifier was improved by using flow tubes made of samarium-doped glass; the small signal gain reached 20 at its maximum. As a result, an output energy of 7.66 J at 100 Hz was successfully achieved, and the performance exceeded the target performance (5 J, 100 Hz).
Solitary waves in a general class of granular dimer chains
Authors: Jayaprakash K. R. , Vakakis Alexander F. , Starosvetsky Yuli
Published: August 2012

We report on a countable infinity of traveling solitary waves in a class of highly heterogeneous ordered one-dimensional granular media, in particular, granular dimers composed of an infinite number of periodic sets of “heavy” elastic spherical beads in contact with N “light” ones; these media are denoted as 1:N granular dimers. Perfectly elastic Hertzian interaction between beads is assumed and no dissipative forces are taken into account in our study; moreover, zero pre-compression is assumed, rendering the dynamics strongly nonlinear through complete elimination of linear acoustics from the problem. After developing a general asymptotic methodology for the 1:N granular dimer, we focus on the case N=2 and prove numerically and asymptotically the existence of a countable infinity of traveling solitary waves in the 1:2 dimer chain. These solitary waves, which can be regarded as anti-resonances in these strongly nonlinear media, are found to be qualitatively different than those previously studied in homogeneous and 1:1 dimer chains (i.e., composed of alternating heavy and light beads) which possess symmetric velocity waveforms. In contrast, for traveling solitary waves in 1:2 dimers, the velocity waveforms of the responses of the heavy beads are symmetric, whereas those of the light beads are non-symmetric. Interestingly, we show that no such solitary waves can be realized in general 1:N granular dimers with N>2, although near-solitary waves can exist in these systems based on slow-fast frequency approximations.
Band structure of photonic crystal with dispersive and lossy materials using Dirichlet-to-Neumann wave vector eigen equation method
Authors: Jiang Bin , Zhang Yejin , Wang Yufei , Zheng Wanhua
Published: August 2012

We present the Dirichlet-to-Neumann wave vector eigen equation (DtN-WVEE) method to calculate the band structure of photonic crystal (PhC) with dispersive and lossy materials, and then use finite-difference time-domain method to verify the validity of the results of the DtN-WVEE method. Since the material is lossy with a non-zero imaginary part of epsilon, the wave vector of PhC band structure also has a non-zero imaginary part which results in the reduction of the intensity of the mode. We further present the band structure which gives the relationship among the normalized frequency, the real part of the wave vector, and the imaginary part of the wave vector. To our knowledge, the band structure of lossy PhC has not been well studied yet, and our results can be useful in designing the devices using surface plasmon polariton effect.
A generalized kinetic model for heterogeneous gas-solid reactions
Authors: Xu Zhijie , Sun Xin , Khaleel Mohammad A.
Published: August 2012

We present a generalized kinetic model for gas-solid heterogeneous reactions taking place at the interface between two phases. The model studies the reaction kinetics by taking into account the reactions at the interface, as well as the transport process within the product layer. The standard unreacted shrinking core model relies on the assumption of quasi-static diffusion that results in a steady-state concentration profile of gas reactant in the product layer. By relaxing this assumption and resolving the entire problem, general solutions can be obtained for reaction kinetics, including the reaction front velocity and the conversion (volume fraction of reacted solid). The unreacted shrinking core model is shown to be accurate and in agreement with the generalized model for slow reaction (or fast diffusion), low concentration of gas reactant, and small solid size. Otherwise, a generalized kinetic model should be used.
Formulation and implementation of a unitary group adapted state universal multi-reference coupled cluster (UGA-SUMRCC) theory: Excited and ionized state energies
Authors: Sen Sangita , Shee Avijit , Mukherjee Debashis
Published: August 2012

The traditional state universal multi-reference coupled cluster (SUMRCC) theory uses the Jeziorski-Monkhorst (JM) based Ansatz of the wave operator: Ω = ∑μΩμ|ϕμ⟩⟨ϕμ|, where Ωμ = exp (Tμ) is the cluster representation of the component of Ω inducing virtual excitations from the model function ϕμ. In the first formulations, ϕμs were chosen to be single determinants and Tμs were defined in terms of spinorbitals. This leads to spin-contamination for the non-singlet cases. In this paper, we propose and implement an explicitly spin-free realization of the SUMRCC theory. This method uses spin-free unitary generators in defining the cluster operators, {Tμ}, which even at singles-doubles truncation, generates non-commuting cluster operators. We propose the use of normal-ordered exponential parameterization for Ω:∑μ{exp (Tμ)}|ϕμ⟩⟨ϕμ|, where {} denotes the normal ordering with respect to a common closed shell vacuum which makes the “direct term” of the SUMRCC equations terminate at the quartic power. We choose our model functions {ϕμ} as unitary group adapted (UGA) Gel'fand states which is why we call our theory UGA-SUMRCC. In the spirit of the original SUMRCC, we choose exactly the right number of linearly independent cluster operators in {Tμ} such that no redundancies in the virtual functions \documentclass[12pt]{minimal}\begin{document}$\lbrace \chi _\mu ^l\rbrace$\end{document}{χμl} are involved. Using example applications for electron detached/attached and h-p excited states relative to a closed shell ground state we discuss how to choose the most compact and non-redundant cluster operators. Although there exists a more elaborate spin-adapted JM-like ansatz of Datta and Mukherjee (known as combinatoric open-shell CC (COS-CC), its working equations are more complex. Results are compared with those from COS-CC, equation of motion coupled cluster methods, restricted open-shell Hartree-Fock coupled cluster, and full configuration interaction. We observe that our results are more accurate with respect to most other theories as a result of the use of the cluster expansion structure for our wave operator. Our results are comparable to those from the more involved COS-CC, indicating that our theory captures the most important aspects of physics with a considerably simpler scheme.
Ab initio ground state phenylacetylene–argon intermolecular potential energy surface and rovibrational spectrum
Authors: Cybulski Hubert , Fernández Berta , Henriksen Christian , Felker Peter M.
Published: August 2012

We evaluate the phenylacetylene–argon intermolecular potential energy surface by fitting a representative number of ab initio interaction energies to an analytic function. These energies are calculated at a grid of intermolecular geometries, using the CCSD(T) method and the aug-cc-pVDZ basis set extended with a series of 3s3p2d1f1g midbond functions. The potential is characterized by two equivalent global minima where the Ar atom is located above and below the phenylacetylene plane at a distance of 3.5781 Å from the molecular center of mass and at an angle of 9.08° with respect to the axis perpendicular to the phenylacetylene plane and containing the center of mass. The calculated interaction energy is −418.9 cm−1. To check further the potential, we obtain the rovibrational spectrum of the complex and the results are compared to the available experimental data.
Dynamical reaction pathways in Eley-Rideal recombination of nitrogen from W(100)
Authors: Quintas-Sánchez E. , Larrégaray P. , Crespos C. , Martin-Gondre L. , Rubayo-Soneira J. , Rayez J.-C.
Published: August 2012

The scattering of atomic nitrogen over a N-pre-adsorbed W(100) surface is theoretically described in the case of normal incidence off a single adsorbate. Dynamical reaction mechanisms, in particular Eley-Rideal (ER) abstraction, are scrutinized in the 0.1–3.0 eV collision energy range and the influence of temperature on reactivity is considered between 300  and 1500 K. Dynamics simulations suggest that, though non-activated reaction pathways exist, the abstraction process exhibits a significant collision energy threshold (0.5 eV). Such a feature, which has not been reported so far in the literature, is the consequence of a repulsive interaction between the impinging and the pre-adsorbed nitrogens along with a strong attraction towards the tungsten atoms. Above threshold, the cross section for ER reaction is found one order of magnitude lower than the one for hot-atoms formation. The abstraction process involves the collision of the impinging atom with the surface prior to reaction but temperature effects, when modeled via a generalized Langevin oscillator model, do not affect significantly reactivity.
Structural phases formed by NO2/CO co-adsorption on Au{111} surfaces
Authors: Zhang Tianfu , King David A. , Driver Stephen M.
Published: August 2012

Exposing a Au{111} surface to NO2 and then to CO at temperatures around 120 K in ultra-high vacuum gives rise to molecular overlayers in which the two species are co-adsorbed, which we have investigated using low-temperature scanning tunnelling microscopy. Under NO2-rich conditions, a (√7 × √7)R19.1° phase with 3:1 NO2:CO stoichiometry forms. Under CO-rich conditions, this phase co-exists with other phases having 2:1 and 1:1 NO2:CO stoichiometries and different symmetries, and with bare Au surface. Structural models for these phases are discussed. Individual domains of the (√7 × √7)R19.1° phase are chiral, by virtue of the arrangement of their achiral components, an observation that may have more general implications.
Multiscale reactive molecular dynamics
Authors: Knight Chris , Lindberg Gerrick E. , Voth Gregory A.
Published: August 2012

Many processes important to chemistry, materials science, and biology cannot be described without considering electronic and nuclear-level dynamics and their coupling to slower, cooperative motions of the system. These inherently multiscale problems require computationally efficient and accurate methods to converge statistical properties. In this paper, a method is presented that uses data directly from condensed phase ab initio simulations to develop reactive molecular dynamics models that do not require predefined empirical functions. Instead, the interactions used in the reactive model are expressed as linear combinations of interpolating functions that are optimized by using a linear least-squares algorithm. One notable benefit of the procedure outlined here is the capability to minimize the number of parameters requiring nonlinear optimization. The method presented can be generally applied to multiscale problems and is demonstrated by generating reactive models for the hydrated excess proton and hydroxide ion based directly on condensed phase ab initio molecular dynamics simulations. The resulting models faithfully reproduce the water-ion structural properties and diffusion constants from the ab initio simulations. Additionally, the free energy profiles for proton transfer, which is sensitive to the structural diffusion of both ions in water, are reproduced. The high fidelity of these models to ab initio simulations will permit accurate modeling of general chemical reactions in condensed phase systems with computational efficiency orders of magnitudes greater than currently possible with ab initio simulation methods, thus facilitating a proper statistical sampling of the coupling to slow, large-scale motions of the system.
Micro optical power meter for direct in situ measurement of light transmitted from microscopic systems and focused on micro-samples
Authors: Zhang Gangping , Huang Yao-Xiong
Published: August 2012

This paper reports a micro optical power meter which is able to perform effective and precise measurement on the optical power at the focus of different microscopic systems. The power meter can be easily placed on the stages of different microscopes and even partly immersed into solution to directly measure the optical power transmitted from the microscope objective and focused on the sample suspended in solution. The testing experiments demonstrated that the power meter has the characteristics of high precision, excellent linearity, high sensitivity, good stability, and high responding speed. It can accurately measure power levels from 0.1 to 50 mW in visible wavelength in various conditions and environments, which may encounter in practical applications. The optical power measurements using the power meter performed in some biological cell culturing solutions and in air for the same laser light reveal the first time that the powers measured in solutions were about 5%–8% greater than that measured in air at the same position. This not only suggests the necessity of performing direct measurement in situ in solution to obtain the real optical power projected on the suspended samples, but also indicates that such a micro optical power meter can meet almost all the requirements of optical power measurement in different fields from biomedicine to material sciences.
Near-exit flow physics of a moderately overpressured jet
Authors: Saffaraval Farhad , Solovitz Stephen A.
Published: August 2012

The developing region of high-speed jets is studied using particle image velocimetry methods. Ensemble-averaged and fluctuating velocity profiles were measured at a range of exit pressures, from a subsonic pressure-balanced case to an overpressured condition 3.2 times atmospheric. When pressure-balanced, the mean flow structure showed gradual development to a bell-shaped profile at approximately 8 diameters downstream, but the turbulent Reynolds stresses were far below self-similar levels. When overpressured, the mean structure displayed a series of compressions and expansions, including a normal shock, and the flow was far from Gaussian after 8 downstream diameters. The turbulent stresses were more suppressed than in the pressure-balanced jet, with little change exhibited in the jet core except very near the normal shock. Instantaneous vorticity contours also showed that the shear layer was divided into two bands at overpressure. This suggests that the turbulent eddies driving entrainment in the near-exit region were substantially weaker than in the self-similar region, which would result in lower mass flow from the ambient.
Characterization of grain boundaries in multicrystalline silicon with high lateral resolution using conductive atomic force microscopy
Authors: Rumler Maximilian , Rommel Mathias , Erlekampf Jürgen , Azizi Maral , Geiger Tobias , Bauer Anton J. , Meißner Elke , Frey Lothar
Published: August 2012

In this work, the electrical characteristics of grain boundaries (GBs) in multicrystalline silicon with and without iron contamination are analyzed by fixed voltage current maps and local I/V curves using conductive AFM (cAFM). I/V characteristics reveal the formation of a Schottky contact between the AFM tip and the sample surface. The impact of both, the polarity of the applied voltage and the illumination by the AFM laser on the behavior of GBs was analyzed systematically. Depending on the polarity of the applied voltage and the iron content of the sample, grain boundaries alter significantly the recorded current flow compared to the surrounding material. The results also show a clear influence of the AFM laser light on the electrical behavior of the grain boundaries. Conductive AFM measurements are furthermore compared to data obtained by electron beam induced current (EBIC), indicating that cAFM provides complimentary information.
Sizeable magnetic circular dichroism of artificially precipitated Co clusters in amorphous carbon
Authors: Hsu H. S. , Su W. Y. , Chien P. C. , Kuo S. T. , Sun S. J. , Chuang P. Y. , Lee C. H. , Hwang G. H.
Published: August 2012

This study examines sizeable magnetic circular dichroism (MCD) in Co(20%)-doped amorphous carbon (a-C) films. While as-grown films exhibit a non-detectable MCD signal, films that undergo rapid thermal annealing (RTA) at 600°C in a vacuum yield broad MCD spectra with a large amplitude of ∼3.9 × 104 deg/cm in saturation field 0.78 T at the σ-σ* gap transition (∼5.5 eV). In such films after RTA, the metastable Co-C bonding is decomposed and suitable Co nanoparticles/a-C interfaces are thus formed. Our results indicate that the large change in MCD is contributed from Co nanoparticles and associated with the spin-dependent electronic structure at the Co/a-C interfaces.