bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Fluorescence in Robotic General Surgery: Review of the Literature and State of the Art
Authors: Marano Alessandra , Priora Fabio , Lenti Luca Matteo , Ravazzoni Ferruccio , Quarati Raoul , Spinoglio Giuseppe
Published: May 2013

The initial use of the indocyanine green fluorescence imaging system was for sentinel lymph node biopsy in patients with breast or colorectal cancer. Since then, application of this method has received wide acceptance in various fields of surgical oncology, and it has become a valid diagnostic tool for guiding cancer treatment. It has also been employed in numerous conventional surgical procedures with much success and benefit to the patient. The advent of minimally invasive surgery brought with it a new use for fluorescence in helping to improve the safety of these procedures, particularly for single‐site procedures. In 2010, a near‐infrared camera was integrated into the da Vinci Si System, creating a combination of technical and minimally invasive advantages that have been embraced by several experienced surgeons. The use of fluorescence, although useful, is considered challenging. Only a few studies are currently available on the use of fluorescence in robotic general surgery, whereas many articles have focused on its application in open and laparoscopic surgery. Many of these reports describe promising and satisfactory results, although with some shortcomings. The purpose of this article is to review the current status of the use of fluorescence in general surgery and particularly its role in robotic surgery. We also review potential uses in the future.
Dynamic Neuromusculoskeletal Ultrasound Documentation of Brachial Plexus/Thoracic Outlet Compression during Elevated Arm Stress Testing
Authors: Fried Scott M. , Nazarian Levon N.
Published: May 2013

Background

The diagnosis and validation of thoracic outlet syndrome/brachial plexopathy (TOS) remains a difficult challenge for surgeons, neurologists, and radiologists. This is due to the fact that the responses of standard elevated arm stress tests can be considered somewhat subjective and can vary. Therefore, non-vascular TOS cases are presently diagnosed clinically, and any objective diagnosis has been controversial.

Methods

This is a technique paper describing the use of dynamic neuromusculoskeletal ultrasound to assist in the diagnosis of thoracic outlet/brachial plexus pathology. We propose a new way to observe the brachial plexus dynamically, so that physical verification of nerve compression between the anterior and middle scalene muscles can be clearly made at the onset of clinical symptoms. This gives away to objectively identify clinically significant brachial plexus compression.

Results

Dynamic testing can add objective analysis to tests such as the elevated arm stress tests and can correlate the onset of symptoms with plexus compression between the anterior and middle scalene muscles. With this, the area of pathologic compression can be identified and viewed while performing the dynamic testing. If compression is seen and the onset of symptoms ensues, this is a positive confirmatory test for the presence of TOS and a clinically significant disease.

Conclusions

This paper offers a simple, objective, and visual diagnostic test that can validate the presence or absence of brachial plexus compression during arm elevation in patients with brachial plexus injury and thoracic outlet syndrome. The online version of this article (doi:10.1007/s11552-013-9523-8) contains a video.
Raphael Cilento in Medicine and Politics
Authors: Finnane Mark
Published: May 2013

At the end of his working life as a medical bureaucrat, Raphael Cilento twice tried his hand at Australian federal politics. After an initial joust at a Senate seat, he was encouraged by the fledgling Australian Democratic Union to try the House of Representatives. His choice of electorate was heroic. The seat of McPherson (Qld) was held by Arthur Fadden, one time prime minister and perennial member for this Darling Downs electorate. Standing as an ‘Independent Democrat’, Cilento targeted the Italian community in Stanthorpe, a district where he picked up half the vote in his otherwise unsuccessful campaign. His candidature attracted some notice. Brisbane's Truth described Sir Raphael as ‘the most distinguished Queenslander to ever enter the Federal political arena’. This might seem a little hyperbolic, but seen in the larger context of Cilento's national and international work, it was a defensible proposition. Seen literally, it is slightly less defensible since Cilento was not Queensland born. Rather, he came to adopt Queensland — and to seek to advance its standing as an example of successful white settlement of the tropics.
Sugar and Ecological Imperialism
Authors: Moore Clive
Published: May 2013

The Pioneer Valley at Mackay is the centre of a thriving sugar industry that supports 120,000 people and brings millions of dollars into the Australian economy through milling sugar cane. The valley presents a vista of kilometre after kilometre of flat green and brown symmetrical patterns. In the growing season, rectangles striped with furrows carry on as far as the eye can see, blending into green blocks as the cane grows, with the pattern broken only by natural topographic features such as creeks, the Pioneer River, occasional hills and small towns. Cane totally dominates the flat land, but at the edges of the valley it is gradually overshadowed by the brown and grey of the higher untamed areas. Within this green, brown and grey picture is another pattern, the imposed logistics of roads, railways, and glistening galvanised roofs on the houses and sheds, softened by the dark green of mango and other fruit trees, stately hoop pines, fig and shade trees. On the edges of the valley floor, the hills become more numerous, feeding into the surrounding mountain ranges. The visual pattern partly relates to topography, but includes elements dating back to the shapes of the first land selections and subsequent surveying from the 1860s onwards, as well as the need for road and rail links between early settlements, and more recently by the needs of modern mechanical farming.
‘HOT MONEY’: GENDER AND THE POLITICS OF NEGOTIATION AND CONTROL OVER INCOME IN WEST AFRICAN SMALLHOLDER HOUSEHOLDS
Authors: Somé Batamaka
Published: May 2013

Most development interventions targeting rural women's economic empowerment measure success through returns from women's on-farm or off-farm activities and the income they generate. This article suggests that special emphasis needs to be laid on income control, not just its generation, in order to take account of the more or less subtle socio-cultural obstacles and other structures of constraint hindering women in this regard. The article draws from ethnographic case studies conducted for a doctoral dissertation project in south-west Burkina Faso to show how women in cotton-farming zones strategize to circumvent customary rules and control their on-farm incomes. The context is an organic cotton-farming project targeting women. I argue that understanding these constraints and strategies provides policy makers and development practitioners with tools for a better grasp of the social landscape – and that this, in turn, enables them to reach empowerment goals.
SURVIVAL STRATEGIES AND CITIZENSHIP CLAIMS: YOUTH AND THE UNDERGROUND OIL ECONOMY IN POST-AMNESTY NIGER DELTA
Authors: Ugor Paul U.
Published: May 2013

Focusing on Gbekebor, a small rural community in Burutu Local Government Area in Delta State, this article examines the rise of small-scale artisanal oil refineries in the oil-rich Niger Delta area in south-eastern Nigeria. Mostly owned and run by unemployed youth in the Delta region, this informal underground oil economy is a classic example of the ways in which the mass of disgruntled youth in Nigeria have now evolved their own new survival strategies in the face of inauspicious social and economic conditions in everyday life. In the article, therefore, I argue that the growth of illegal refineries in the Niger Delta region represents ordinary people's desperate search for economic and social justice for themselves and their communities when the state and superordinate economic regimes (oil corporations) operating in the Delta area have connived to deny ordinary people their social and economic rights as citizens.
EXTRACTION OFFSHORE, POLITICS INSHORE, AND THE ROLE OF THE STATE IN EQUATORIAL GUINEA
Authors: Campos-Serrano Alicia
Published: May 2013

Recent economic and socio-political dynamics in the territories that form Equatorial Guinea are related, in different ways, to the extraction of hydrocarbons from its Exclusive Economic Zone since the mid-1990s. These transformations are strongly mediated by specific social groups, especially the family that has held power since 1968 and transnational oil companies, whose relationships are central to the exclusive political configuration in the country. The article analyses this particular form of extraversion of power as part of a broader history of the region, in which the role of the state's sovereignty as articulated during decolonization is shown to be instrumental in the allocation of rights and the political economy of oil today. The article also discusses the spaces that the new political economy of oil has opened for alternative transnational connections around the country.
An evolutionary and developmental perspective on the loss of regionalization in the limbs of derived ichthyosaurs
Authors: MAXWELL ERIN E. , SCHEYER TORSTEN M. , FOWLER DONALD A.
Published: May 2013

Ichthyosaurs, a lineage of extinct Mesozoic marine reptiles, have garnered attention in both the palaeontological and developmental literature for the unique limb morphology seen in derived genera. These morphologies include an increase in the number of phalanges per digit (hyperphalangy) and in the number of digits (hyperdactyly), but most interestingly also a shift in element identity. Elements distal to the stylopodium acquire characteristics of mesopodial elements, such as a rounded, nodular shape and a loss of perichondral bone on the anterior and posterior surfaces. Here, we examine numerous aspects of the loss of proximodistal identity in ichthyosaur limbs including phylogenetic progression of the loss of perichondral bone, histology and microstructure of the elements retaining perichondral bone in derived taxa, and correlates of intraspecific variation in degree of perichondral bone reduction in a derived ichthyosaur,Stenopterygius quadriscissus. Results show that loss of limb element identity occurred progressively over ichthyosaurian evolution, and the notches seen on the anterior surface of limb elements in derived ichthyosaurs are homologous to the long bone shafts in terrestrial tetrapods. Variation in the number of notches inS. quadriscissuscan best be explained through delayed ossification of the anterior perichondrium, indicating a heterochronic component to the loss of identity. We propose a developmental mechanism – gradual expansion of the polyalanine region of HoxD13 over ichthyosaurian evolution – to explain the progressive loss of limb regionalization as well as the heterochronic delay in perichondral ossification.
UNDERSTANDING A LANGUAGE OF ‘ARISTOCRACY’, 1700–1850
Authors: GOODRICH AMANDA
Published: May 2013

This article engages with current debates about linguistic usage in a new way. It examines linguistic change, the shifts in frequency of usage of ‘aristocracy’, both qualitatively and quantitatively, at specific moments and over time, in print during the period 1700 to 1850. Digital resources are utilized to provide broad quantitative evidence not previously available to historians. The potential use and value of digitized sources is also explored in calculating the volume and frequency of keyword appearance within a broad set of genres. This article also examines qualitatively usage of ‘aristocracy’ by contemporaries and historians and concludes that historians have often used the term anachronistically. It reveals that for much of the eighteenth century ‘aristocracy’ was entirely a political term confined primarily to the educated elite but that by 1850 it had become a common social descriptor of an elite class. It also compares the trajectory of usage of ‘aristocracy’ with that of ‘democracy’ and accounts for the divergence in such usage. It is argued here that analysing the prevalence and usage of ‘aristocracy’ in contemporary contexts reveals an important narrative of linguistic changes that parallel shifts in political and social culture.
INFRASTRUCTURAL GLOBALIZATION: LIGHTING THE CHINA COAST, 1860s–1930s
Authors: BICKERS ROBERT
Published: May 2013

This article calls for attention to be paid to the infrastructures that underpinned nineteenth-century globalization, and the use of better-known technological developments and global patterns of professional migration. It does so by outlining the work of the Marine Department of the Chinese Maritime Customs Service after 1868, focusing on its development of a network of lighthouses along the coast of China in its political and comparative contexts. These lights were at once local sites and nodes within a developing national and global system, and evolving practices around circulation of data and best practice, accepted international standards, technology transfer, and maritime safety. The Customs Service was a Chinese government agency, albeit within the British orbit of influence, but acted as a buffer between China and foreign interests and pressures.
CONSIGNING JUSTICE TO HISTORY: TRANSITIONAL TRIALS AFTER THE SECOND WORLD WAR
Authors: PRIEMEL KIM CHRISTIAN
Published: May 2013

This article reviews recent historical investigations of transitional trials held after the Second World War. It identifies three main strands of historiography. One group of studies has been dominated by the trials' participants who have shaped the perception of the trials' scope, their achievements, and their shortcomings, and pursued political, legal, or biographical agendas. A second group has treated the trials as a mere epilogue to the history of the deceased regimes. A third, more profound approach has conceptualized the trials as places where collective memory was assembled, configured, and shaped. This notion opens the debate to an analysis of how law and history on the one hand, jurisdiction, jurisprudence, and historiography on the other interact and how they impact on one another. The article compares and evaluates the benefits drawn from this research. It finds that historical analyses which take seriously the epistemological premises of the law as well as the courtroom's performativity manage to bypass well-trodden paths of interpretation which either deplore the limited, inadequate punishment meted out, or celebrate the triumphant march from Nuremberg to The Hague. The article concludes that such interdisciplinary readings help to avoid widespread disillusionment with the results of transitional trials.
Impact of grazing intensity on herbage quality, feed intake and live weight gain of sheep grazing on the steppe of Inner Mongolia
Authors: MÜLLER K. , DICKHOEFER U. , LIN L. , GLINDEMANN T. , WANG C. , SCHÖNBACH P. , WAN H. W. , SCHIBORRA A. , TAS B. M. , GIERUS M. , TAUBE F. , SUSENBETH A.
Published: May 2013

The grassland steppe of Inner Mongolia is traditionally used for sheep grazing. However, overgrazing reduced vegetation cover in winter, thereby increasing soil erosion and consequently, degradation of the steppe vegetation. Grazing intensity (GI) is still the most important factor in pasture management. Hence, the aim of the current study was to evaluate the effect of GI on grassland and sheep performance. A grazing experiment was conducted from July until September in 2005, 2006 and 2007 in which six different GI ranging from very light (GI 1), light (GI 2), light-moderate (GI 3), moderate (GI 4) and heavy (GI 5) to very heavy (GI 6) were tested. Each GI treatment comprised two adjacent plots that were alternately used for grazing or hay-making each year. Variables measured included herbage mass (HM) and chemical composition, digestibility of ingested organic matter (dOM), organic matter intake (OMI) and live weight gain (LWG) of sheep. The HM decreased significantly with increasing GI from 1·01 t (GI 1) to 0·45 t dry matter (DM)/ha (GI 6). There were only minor effects of GI on chemical composition and digestibility of standing herbage. Moreover, dOM, OMI and hence, digestible OMI did not differ between GI. Across all study years, LWG of sheep was not influenced by GI so that LWG per hectare increased with increasing GI, reaching a maximum of 730 g/d at GI 6 compared with 181 g/d at GI 1. However, a strong decrease in LWG per sheep with increasing stocking rate was found in 2005 when annual rainfall was less than half of the long-term average, resulting in a similar LWG per hectare across the range of tested stocking rates. The results therefore show that intensive grazing does not reduce growth of individual animals in most years, but increases LWG per unit of land area and thus, income of farmers. The alternating use of pastures for grazing or hay-making might have mitigated the negative effects of heavy grazing on herbage and animal performance. Nevertheless, high GI may negatively affect grassland productivity in the long term and the lack of HM on offer on heavy grazed pastures in dry years will require supplement feeding at the end of the vegetation period or the untimely sale of animals.
Telltale Tails: A New Approach to Estimating Unique Market Information Shares
Authors: Grammig Joachim , Peter Franziska J.
Published: May 2013

The trading of securities on multiple markets raises the question of each market’s share in the discovery of the informationally efficient price. We exploit salient distributional features of multivariate financial price processes to uniquely determine these contributions, thereby resolving the main drawback of the widely used Hasbrouck (1995) methodology, which merely provides upper and lower bounds of a market’s information share. We show how tail dependence of price changes, which may emerge as a result of differences in market design, can be exploited to estimate unique information shares. Two empiricalapplications illustrate the practical use of the new methodology.
Corporate Governance and Risk Taking in Pension Plans: Evidence from Defined Benefit Asset Allocations
Authors: Phan Hieu V. , Hegde Shantaram P.
Published: May 2013

Based on theoretical advice and empirical evidence suggesting that risk taking in asset allocation enhances pension returns, we evaluate empirically whether good corporate governance leads to a larger allocation of pension assets to risky securities as compared to safe investments. Our findings suggest that firms with good external and internal corporate governance take more risk by investing heavily in equities and allocating a smaller share of the plan assets to cash, government debt, and insurance company accounts. The main underlying mechanisms appear to be higher investment returns and better pension funding status associated with higher equity and lower safe asset allocations.
Dynamics of laser induced micro-shock waves and hot core plasma in quiescent air
Authors: Leela Ch. , Bagchi Suman , Kumar V. Rakesh , Tewari Surya P. , Kiran P. Prem
Published: May 2013

We present our results on spatio-temporal evolution of laser plasma produced shockwaves (SWs) and hot core plasma (HCP) created by focused second harmonic (532 nm, 7 ns) of Nd-YAG laser in quiescent atmospheric air at f/#10 focusing geometry. Time resolved shadowgraphs imaged with the help of an ICCD camera with 1.5 ns temporal resolution revealed the presence of two co-existing sources simultaneously generating SWs. Each of the two sources independently led to a spherical SW following Sedov-Taylor theory along the laser propagation direction with a maximum velocity of 7.4 km/s and pressure of 57 MPa. While the interaction of SWs from the two sources led to a planar SW in the direction normal to the laser propagation direction. The SW detaches from the HCP and starts expanding into the ambient air at around 3 µs indicating the onset of asymmetric expansion of the HCP along the z-axis. The asymmetric expansion is observed till 10 µs beyond which the SW leaves the field of view followed by a deformation of the irradiated region in the XY-plane due to the penetration of surrounding colder air in to the HCP. The deformation in the XY-plane lasts till 600 µs. The dynamics of rapidly expanding HCP is observed to be analogous to that of cavitation bubble dynamics in fluids.
Characterization of a dual-gas multi-jet gas puff target for high-order harmonic generation using extreme ultraviolet shadowgraphy
Authors: Wachulak P.W. , Wegrzynski L. , Bartnik A. , Fok T. , Jarocki R. , Kostecki J. , Szczurek M. , Fiedorowicz H.
Published: May 2013

Characterization measurements and modes of operation of a novel, dual-gas multi-jet target, developed for experiments on high-order harmonic generation, are presented. The target has been formed by pulsed injection of argon through a nozzle in a form of linearly oriented small orifices. The argon jets were separated with the helium jets formed by injection of helium through alternate orifices in the nozzle. The targets have been characterized by extreme ultraviolet backlighting at 13.5 nm wavelength. Density profiles for this type of targets have been obtained, to our knowledge, for the first time.
Should International Law Ensure the Moral Acceptability of War?
Authors: DILL JANINA
Published: May 2013

Jeff McMahan's challenge to conventional just-war theory is an attempt to apply to the use of force between states a moral standard whose pertinence to international relations (IR) is decreasingly contestable and the regulation of which international law (IL) is, therefore, under pressure to afford: the preservation of individual rights. This compelling endeavour is at an impasse given the admission of many ethicists that it is currently impossible for international humanitarian law (IHL) to regulate killing in war in accordance with individuals’ liability. IHL's failure to consistently protect individual rights, specifically its shortfall compared to human rights law, has raised questions about IHL's adequacy also among international lawyers. This paper identifies the features of war that ground the inability of IL to regulate it to a level of moral acceptability and characterizes the quintessential war as presenting what I call an ‘epistemically cloaked forced choice’ regarding the preservation of individual rights. Commitment to the above moral standard, then, means that IL should not prejudge the outcome of wars and must, somewhat paradoxically, diverge from morality when making prescriptions about the conduct of hostilities. In showing that many confrontations between states inevitably take the form of such epistemically cloaked forced choices, the paper contests the argument by revisionist just-war theorists like McMahan that the failure of IL to track morality in war is merely a function of contingent institutional desiderata. IHL, with its moral limitations, has a continuing role to play in IR.
TALENT UTILIZATION AND SEARCH FOR THE APPROPRIATE TECHNOLOGY
Authors: Regev Tali , Zoabi Hosny
Published: May 2013

This paper presents a model of development that is driven by matching between talents and technologies. Differences in productivity across countries are amplified by three dimensions of talent utilization: the range of talents utilized, the density of a specific talent utilized, and the average match quality in the economy. In our model, higher productivity increases the number of technologies available, enhancing the opportunities for individuals to match their talents to specific technologies and increasing the returns to search. More intensive search further contributes to talent utilization.
Azimuthal Projections: Data Rotation and Projection Switching in Real Time
Authors: Nolze Gert
Published: May 2013

Pole figures are often used to present crystal orientation data. The huge number of single orientation measurements acquired by electron backscatter diffraction (EBSD) poses a challenge for pole figure representation due to the large number of calculations required. This significantly reduces the speed at which the data may be rotated and affects the ability to switch between different projection types. In the present work, it will be shown that satisfactory representation of orientation data in different projection types can generally be achieved by an imaging of a spherical projection. With this approach, explicit calculation of the projections is no longer required, allowing for both real-time dataset rotation and real-time switching between all projection types relevant to materials science. The technique can be applied to any other directional property distribution, for example, not only for EBSD orientation presentation.
A VARIANT OF HOFSTADTER’S SEQUENCE AND FINITE AUTOMATA
Authors: ALLOUCHE JEAN-PAUL , SHALLIT JEFFREY
Published: May 2013

Following up on a paper of Balamohan et al. [‘On the behavior of a variant of Hofstadter’s $q$-sequence’, J. Integer Seq. 10 (2007)], we analyze a variant of Hofstadter’s $Q$-sequence and show that its frequency sequence is 2-automatic. An automaton computing the sequence is explicitly given.
Die Wirksamkeit neuropsychologischer Trainingsverfahren bei Kindern und Jugendlichen mit Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS)
Authors: Amonn Frauke , Frölich Jan , Döpfner Manfred
Published: May 2013

Aktuelle neuropsychologische Erkenntnisse zur Pathogenese von Aufmerksamkeitsdefizit-Hyperaktivitätsstörungen haben in jüngster Zeit verstärkt zur Untersuchung der Effektivität spezifischer Trainings- und Therapieverfahren der betroffenen kognitiven Defizite beigetragen. In der vorliegenden Übersicht wurden über eine Medline-Recherche die Ergebnisse bereits vorliegender neuropsychologischer Therapieverfahren zusammengetragen. Aufgrund der geringen Studienzahl auf diesem Gebiet wurden neben randomisierten Studien zum Teil Arbeiten mit geringerem Evidenzgrad einbezogen, zum Teil auch Einzelfallberichte. Als Suchwörter wurden verwendet: Kognitive Trainings und Behandlungsverfahren, neuropsychologische Behandlungsverfahren, computergestützte Behandlungsverfahren/-trainings bei ADHS. Die Ergebnisse der vorliegenden Studien lassen aufgrund der heterogenen Zusammensetzung der Studienkollektive, der Anwendung unterschiedlicher diagnostischer Kriterien, der Effektmessung, der Verwendung sehr unterschiedlicher Trainingsverfahren als auch der Behandlungsdauer nur sehr vorläufige Schlussfolgerungen auf deren Wirksamkeit zu. Auch der Grad der Generalisierung von Therapieeffekten verbleibt bislang unklar. Trotz der oben genannten Einschränkungen weisen die vorliegenden Studienergebnisse darauf hin, dass neuropsychologische Therapieverfahren zumindest in der Behandlung einiger spezifischer kognitiver Defizite wirksam sein könnten. Als nächster Schritt wären Replikationsstudien unter der Verwendung vergleichbarer Therapiemodule und -bedingungen bei homogenen Stichproben erforderlich.
The N-terminal region of two-pore channel 1 regulates trafficking and activation by NAADP
Authors: Churamani Dev , Hooper Robert , Rahman Taufiq , Brailoiu Eugen , Patel Sandip
Published: May 2013

TPCs (two-pore channels) are NAADP (nicotinic acid–adenine dinucleotide phosphate)-sensitive Ca2+-permeable ion channels expressed on acidic organelles. In the present study we show that deletion of the N-terminal region redirects TPC1 to the ER (endoplasmic reticulum). The introduction of fluorophores at the N-terminus of TPC1 does not affect its subcellular location, but does reversibly abolish NAADP sensitivity. Our results reveal a dual role for the N-terminus in localization and function of TPC1.
Influence of uniaxial stress on the ferroelectric-to-paraelectric phase change in barium titanate
Authors: Schader Florian H. , Aulbach Emil , Webber Kyle G. , Rossetti George A.
Published: May 2013

The dielectric behavior near the ferroelectric-to-paraelectric phase transition of 〈001〉C-oriented single crystal and polycrystalline barium titanate (BaTiO3) was investigated as a function of uniaxial compressive stress in the temperature range from 25 to 200 °C. An increase in the Curie point (TC) and decrease in the Curie-Weiss temperature (θ) were observed with increasing stress for both single crystal and polycrystalline samples, resulting in an increase in the first order nature of the phase transition as measured by the temperature difference (TC – θ). With increasing applied stress levels, the permittivity versus temperature curves of polycrystalline samples were found to broaden and flatten near the Curie point, which was not observed for the single crystals. The experimental results were analyzed using a classical 2-4-6 Landau polynomial. The observed increase in the first order nature of the ferroelectric-to-paraelectric phase transition with uniaxial stress was explained by a linear dependence of the quartic coefficient of the Landau series on stress.
Structural and magnetic characterization of the intermartensitic phase transition in NiMnSn Heusler alloy ribbons
Authors: Sánchez Llamazares J. L. , Flores-Zúñiga H. , Ríos-Jara D. , Sánchez-Valdes C. F. , García-Fernández T. , Ross C. A. , García C.
Published: May 2013

Phase transitions and structural and magnetic properties of rapidly solidified Ni50Mn38Sn12 alloy ribbons have been studied. Ribbon samples crystallize as a single-phase, ten-layered modulated (10M) monoclinic martensite with a columnar-grain microstructure and a magnetic transition temperature of 308 K. By decreasing the temperature, martensite undergoes an intermartensitic phase transition around 195 K. Above room temperature, the high temperature martensite transforms into austenite. Below 100 K, magnetization hysteresis loops shift along the negative H-axis direction, confirming the occurrence of an exchange bias effect. On heating, the thermal dependence of the coercive field HC shows a continuous increase, reaching a maximum value of 1017 Oe around 50 K. Above this temperature, HC declines to zero around 195 K. But above this temperature, it increases again up to 20 Oe falling to zero close to 308 K. The coercivity values measured in both temperature intervals suggest a significant difference in the magnetocrystalline anisotropy of the two martensite phases.
A linear- and sublinear-scaling method for calculating NMR shieldings in atomic orbital-based second-order Møller-Plesset perturbation theory
Authors: Maurer Marina , Ochsenfeld Christian
Published: May 2013

An atomic-orbital (AO) based formulation for calculating nuclear magnetic resonance chemical shieldings at the second-order Møller-Plesset perturbation theory level is introduced, which provides a basis for reducing the scaling of the computational effort with the molecular size from the fifth power to linear and for a specific nucleus to sublinear. The latter sublinear scaling in the rate-determining steps becomes possible by avoiding global perturbations with respect to the magnetic field and by solving for quantities that involve the local nuclear magnetic spin perturbation instead. For avoiding the calculation of the second-order perturbed density matrix, we extend our AO-based reformulation of the Z-vector method within a density matrix-based scheme. Our pilot implementation illustrates the fast convergence with respect to the required number of Laplace points and the asymptotic scaling behavior in the rate-determining steps.
A nonempirical scaling correction approach for density functional methods involving substantial amount of Hartree–Fock exchange
Authors: Zheng Xiao , Zhou Ting , Yang Weitao
Published: May 2013

A nonempirical scaling correction (SC) approach has been developed for improving bandgap prediction in density functional theory [X. Zheng, A. J. Cohen, P. Mori-Sánchez, X. Hu, and W. Yang, Phys. Rev. Lett. 107, 026403 (2011)10.1103/PhysRevLett.107.026403]. For finite systems such as atoms and molecules, the SC approach restores the Perdew–Parr–Levy–Balduz condition [Phys. Rev. Lett. 49, 1691 (1982)10.1103/PhysRevLett.49.1691] that the total electronic energy should scale linearly with number of electrons between integers. Although the original SC approach is applicable to a variety of mainstream density functional approximations, it gives zero correction to the Hartree–Fock method. This is because the relaxation of orbitals with the change in electron number is completely neglected. In this work, with an iterative scheme for the evaluation of Fukui function, the orbital relaxation effects are accounted for explicitly via a perturbative treatment. In doing so, the SC approach is extended to density functionals involving substantial amount of Hartree–Fock exchange. Our new SC approach is demonstrated to improve systematically the predicted Kohn–Sham frontier orbital energies, and alleviate significantly the mismatch between fundamental and derivative gaps.
Effects of temperature dependent pre-amorphization implantation on NiPt silicide formation and thermal stability on Si(100)
Authors: Ozcan Ahmet S. , Wall Donald , Jordan-Sweet Jean , Lavoie Christian
Published: May 2013

Using temperature controlled Si and C ion implantation, we studied the effects of pre-amorphization implantation on NiPt alloy silicide phase formation. In situ synchrotron x-ray diffraction and resistance measurements were used to monitor phase and morphology evolution in silicide films. Results show that substrate amorphization strongly modulate the nucleation of silicide phases, regardless of implant species. However, morphological stability of the thin films is mainly enhanced by C addition, independently of the amorphization depth.
High-resolution electron spin resonance analysis of ion bombardment induced defects in advanced low-κ insulators (κ = 2.0-2.5)
Authors: Afanas'ev V. V. , Nguyen A. P. D. , Houssa M. , Stesmans A. , Tőkei Zs. , Baklanov M. R.
Published: May 2013

Electron spin resonance analysis of defects generated by ion bombardment in different low-permittivity (low-κ) SiO2-based insulating films reveals common types of encountered defects: The EX center (g = 2.0025) and a broad line centered at g = 2.0028 tentatively associated with dangling bonds of carbon atoms backbonded to C or Si atoms. The efficiency of defect generation varies, depending on the type of bombarding ions and the technology of insulator synthesis. However, the two identified defects are observed in all studied cases, suggesting that these defects correspond to the most stable atomic configurations resulting from the network damage of the low-κ materials.
Hierarchical Nyström methods for constructing Markov state models for conformational dynamics
Authors: Yao Yuan , Cui Raymond Z. , Bowman Gregory R. , Silva Daniel-Adriano , Sun Jian , Huang Xuhui
Published: May 2013

Markov state models (MSMs) have become a popular approach for investigating the conformational dynamics of proteins and other biomolecules. MSMs are typically built from numerous molecular dynamics simulations by dividing the sampled configurations into a large number of microstates based on geometric criteria. The resulting microstate model can then be coarse-grained into a more understandable macrostate model by lumping together rapidly mixing microstates into larger, metastable aggregates. However, finite sampling often results in the creation of many poorly sampled microstates. During coarse-graining, these states are mistakenly identified as being kinetically important because transitions to/from them appear to be slow. In this paper, we propose a formalism based on an algebraic principle for matrix approximation, i.e., the Nyström method, to deal with such poorly sampled microstates. Our scheme builds a hierarchy of microstates from high to low populations and progressively applies spectral clustering on sets of microstates within each level of the hierarchy. It helps spectral clustering identify metastable aggregates with highly populated microstates rather than being distracted by lowly populated states. We demonstrate the ability of this algorithm to discover the major metastable states on two model systems, the alanine dipeptide and trpzip2 peptide.
On oblique and parallel shedding behind an inclined plate
Authors: Yang Dan , Pettersen Bjørnar , Andersson Helge I. , Narasimhamurthy Vagesh D.
Published: May 2013

Three-dimensional wake instabilities in the form of oblique shedding and vortex dislocations in the flow past an inclined flat plate of angle of attack 20° and Reynolds number 1000 have been reported earlier [D. Yang, B. Pettersen, H. I. Andersson, and V. D. Narasimhamurthy, Phys. Fluids 24, 084103 (2012)]10.1063/1.4744982. In the current study, direct numerical simulations were performed to further explore this bifurcation. At lower Reynolds numbers, i.e., well below 525, the three-dimensional wake was found to be stable and in a parallel shedding mode. However, as the Reynolds number increases, it was observed that both parallel and oblique vortex sheddings arose naturally. Vortex dislocations appeared at the juxtaposition of oblique and parallel shedding modes. The velocity signals were analyzed by a wavelet transformation, from which the instantaneous characteristics of three-dimensional vortex shedding were obtained and examined. Results show that the phase difference of shed vortex rollers in the spanwise direction gave a symmetric probability density function. This indicates that both positive and negative shedding angles (relative to the axis of the plate) occur with equal likelihood.
Trap states in InAlN/AlN/GaN-based double-channel high electron mobility transistors
Authors: Zhang Kai , Xue JunShuai , Cao MengYi , Yang LiYuan , Chen YongHe , Zhang JinCheng , Ma XiaoHua , Hao Yue
Published: May 2013

We present a detailed analysis of trap states in InAlN/AlN/GaN double-channel high electron mobility transistors grown by pulsed metal organic chemical vapor deposition. By frequency dependent conductance measurements, trap densities and time constants at both InAlN/AlN/GaN interfaces were determined. Two types of traps, with a high density of up to ∼1014 cm−2 eV−1, were observed existing at the higher InAlN/AlN/GaN interface. On the other hand, the density dramatically decreased to ∼1012 cm−2 eV−1 for traps located at lower InAlN/AlN/GaN interface on which a low-temperature grown GaN (LT-GaN) layer was deposited. Additionally, photo-assisted capacitance-voltage measurements were performed to estimate deep-level defects, yielding a low density of 1.79 × 1011 cm−2 acting as negative fixed charges at the LT-GaN and lower InAlN interface.
A general moment expansion method for stochastic kinetic models
Authors: Ale Angelique , Kirk Paul , Stumpf Michael P. H.
Published: May 2013

Moment approximation methods are gaining increasing attention for their use in the approximation of the stochastic kinetics of chemical reaction systems. In this paper we derive a general moment expansion method for any type of propensities and which allows expansion up to any number of moments. For some chemical reaction systems, more than two moments are necessary to describe the dynamic properties of the system, which the linear noise approximation is unable to provide. Moreover, also for systems for which the mean does not have a strong dependence on higher order moments, moment approximation methods give information about higher order moments of the underlying probability distribution. We demonstrate the method using a dimerisation reaction, Michaelis-Menten kinetics and a model of an oscillating p53 system. We show that for the dimerisation reaction and Michaelis-Menten enzyme kinetics system higher order moments have limited influence on the estimation of the mean, while for the p53 system, the solution for the mean can require several moments to converge to the average obtained from many stochastic simulations. We also find that agreement between lower order moments does not guarantee that higher moments will agree. Compared to stochastic simulations, our approach is numerically highly efficient at capturing the behaviour of stochastic systems in terms of the average and higher moments, and we provide expressions for the computational cost for different system sizes and orders of approximation. We show how the moment expansion method can be employed to efficiently quantify parameter sensitivity. Finally we investigate the effects of using too few moments on parameter estimation, and provide guidance on how to estimate if the distribution can be accurately approximated using only a few moments.
Pressure induced structural phase transition in solid oxidizer KClO3: A first-principles study
Authors: Yedukondalu N. , Ghule Vikas D. , Vaitheeswaran G.
Published: May 2013

High pressure behavior of potassium chlorate (KClO3) has been investigated from 0 to 10 GPa by means of first principles density functional theory calculations. The calculated ground state parameters, transition pressure, and phonon frequencies using semiempirical dispersion correction scheme are in excellent agreement with experiment. It is found that KClO3 undergoes a pressure induced first order phase transition with an associated volume collapse of 6.4% from monoclinic (P21/m) → rhombohedral (R3m) structure at 2.26 GPa, which is in good accord with experimental observation. However, the transition pressure was found to underestimate (0.11 GPa) and overestimate (3.57 GPa) using local density approximation and generalized gradient approximation functionals, respectively. Mechanical stability of both the phases is explained from the calculated single crystal elastic constants. In addition, the zone center phonon frequencies have been calculated using density functional perturbation theory at ambient as well as at high pressure and the lattice modes are found to soften under pressure between 0.6 and 1.2 GPa. The present study reveals that the observed structural phase transition leads to changes in the decomposition mechanism of KClO3 which corroborates with the experimental results.
A characterization of the Helmholtz free energy
Authors: Sanami Abolfazl
Published: May 2013

Let \documentclass[12pt]{minimal}\begin{document}$\mathcal {{{H}}}$\end{document}H be a finite dimensional complex Hilbert space, \documentclass[12pt]{minimal}\begin{document}${\mathbb {B}}(\mathcal {{{H}}})_{+}$\end{document}B(H)+ be the set of all positive semi-definite operators (matrices) on \documentclass[12pt]{minimal}\begin{document}$\mathcal {{{H}}}$\end{document}H and φ is a (not necessarily linear) map of \documentclass[12pt]{minimal}\begin{document}${\mathbb {B}}(\mathcal {{{H}}})_{+}$\end{document}B(H)+ preserving the generalized Helmholtz free energy. In this paper, under suitable conditions we prove that there exists either a unitary or an anti-unitary operator U on \documentclass[12pt]{minimal}\begin{document}$\mathcal {{{H}}}$\end{document}H such that φ(A) = UAU* for any \documentclass[12pt]{minimal}\begin{document}$A \in {\mathbb {B}}(\mathcal {{{H}}})_{+}$\end{document}A∈B(H)+.
Metal–organic frameworks with wine-rack motif: What determines their flexibility and elastic properties?
Authors: Ortiz Aurélie U. , Boutin A. , Fuchs Alain H. , Coudert François-Xavier
Published: May 2013

We present here a framework for the analysis of the full tensors of second-order elastic constants of metal–organic frameworks, which can be obtained by ab initio calculations. We describe the various mechanical properties one can derive from such tensors: directional Young's modulus, shear modulus, Poisson ratio, and linear compressibility. We then apply this methodology to four different metal–organic frameworks displaying a wine-rack structure: MIL-53(Al), MIL-47, MIL-122(In), and MIL-140A. From these results, we shed some light into the link between mechanical properties, geometric shape, and compliance of the framework of these porous solids. We conclude by proposing a simple criterion to assess the framework compliance, based on the lowest eigenvalue of its second-order elastic tensor.
Adsorption induced transitions in soft porous crystals: An osmotic potential approach to multistability and intermediate structures
Authors: Bousquet David , Coudert François-Xavier , Fossati Alexandre G. J. , Neimark Alexander V. , Fuchs Alain H. , Boutin Anne
Published: May 2013

Soft porous crystals are flexible metal-organic frameworks that respond to physical stimuli (temperature, pressure, and gas adsorption) by large changes in their structure and unit cell volume. We propose here a thermodynamic treatment, based on the osmotic ensemble, of the interplay between guest adsorption and host deformation, where the bare host material can undergo elastic deformation, as well as structural transitions between metastable phases in the case of a multistable material. We show that in addition to structural transitions between metastable phases of bistable or multistable host frameworks, a new guest-stabilized host phase can be created when the size of the adsorbate is larger than the empty material's pore size. We then confront the findings of our approach with experimental data for systems exhibiting phenomena such as gate opening and breathing.
Low energy (e,2e) coincidence studies of NH3: Results from experiment and theory
Authors: Nixon Kate L. , Murray Andrew James , Chaluvadi Hari , Ning Chuangang , Colgan James , Madison Don H.
Published: May 2013

Experimental and theoretical triple differential cross sections (TDCS) from ammonia are presented in the low energy regime with outgoing electron energies from 20 eV down to 1.5 eV. Ionization measurements from the 3a1, 1e1, and 2a1 molecular orbitals were taken in a coplanar geometry. Data from the 3a1 and 1e1 orbitals were also obtained in a perpendicular plane geometry. The data are compared to predictions from the distorted wave Born approximation and molecular-three-body distorted wave models. The cross sections for the 3a1 and 1e1 orbitals that have p-like character were found to be similar, and were different to that of the 2a1 orbital which has s-like character. These observations are not reproduced by theory, which predicts the structure of the TDCS for all orbitals should be similar. Comparisons are also made to results from experiment and theory for the iso-electronic targets neon and methane.
Improved ion acceleration via laser surface plasma waves excitation
Authors: Bigongiari A. , Raynaud M. , Riconda C. , Héron A.
Published: May 2013

The possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10λ0), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities ranging from 1019 to 1020 Wcm−2μm2. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find an enhancement of the maximum ion energy of a factor ∼2 compared to the cases where the target surface is flat.