bluuebunny/crossref_metadata_2025 huggingface dataset:
Disposition of Aquifer System, Geo-electric Characteristics and Gamma-log Anomaly in the Kuttanad Alluvium of Kerala
Authors: Vinayachandran N. , Narayana A. C. , Najeeb K. MD. , Narendra P.
Published: March 2013

Kuttanad near the western coast of Kerala is a low lying area below mean sea level. The hydrogeological scenario in this wet land dominated tract, known as kole lands, was investigated by using the lithological and geophysical data generated under the R&D exploration programme of Central Ground Water Board (CGWB) during the year 2000, as also other related data generated till the year 2009. The hydrogeology of the tract is complex, and the presence of carbonaceous and organic matter in the soil and sub-soil influences the geochemical and geo-electric characteristics of the sub-surface geological formations as reflected by SP and resistivity logs. The lithologs and geophysical logs of bore wells were used to define the aquifer geometry. While the lateral and vertical variations of the aquifer systems identified were high, the bottom aquifer was relatively brackish over a large area. The gamma log behavior in these granular zones is anomalous and misguiding in nature. The radioactivities recorded against clay horizons were in the range of 130 to 200cps and in the granular zones 150 to 350 cps. The presence of monazite bearing sands at certain depths was responsible for anomalously high gamma counts against granular zones. The water quality in the granular zones was inferred from the electrical logs. The depth of occurrence of high radiation sand beds was also demarcated.
Geology and Geochemistry of Archaean Felsic Metavolcanic Rocks of the Eastern Part of the Kolar Greenstone Belt, Dharwar Craton, India: Implications for their Petrogenesis and Geodynamic Setting
Authors: Ugarkar A. G. , Solankar S. N. , Vasudev V. N.
Published: March 2013

In the Kolar greenstone belt of the Dharwar craton, felsic metavolcanics are encountered prominently in its eastern region around Surapalli and Marikoppa. These felsic volcanic rocks are essentially homogeneous and their bulk mineralogy is almost the same. They consist of phenocrysts of quartz and feldspar, set in a fine-grained quartzo-feldspathic groundmass. They are calc-alkaline rhyolite in composition, and are characterized by high SiO2 (av. 75.74 wt.%), moderate Al2O3 (av. 11.84 wt.%), Na2O (av. 3.55 wt.%), K2O (av. 3.26 wt%) contents and low Mg# (av. 6.07), Cr (av. 8 ppm), Ni (av. 8 ppm), Sr (av. 331 ppm.), Y (av. 7 ppm), Yb (av. 0.87 ppm) and Nb/Ta (av. 6.40) values, suggesting Tonalite-Trondhjemite-Granodiorite (TTG) affinity for these felsic volcanics. They are strongly fractionated [(La/Yb)N- =14.41 -48.70] with strong LREE enrichment [(La/Sm)N = 2.50-3.59] and strong HREE depletion [(Gd/Yb)N = 1.34 - 2.77] with positive Eu anomaly. The regional geological set-up, petrographic and geochemical characteristics suggest that these felsic volcanics probably were derived by partial melting of a subducting basalt slab at shallow depth without much involvement of mantle wedge in an island arc geodynamic setting.
Transgenerational effects of neonatal hypoxia‐ischemia in progeny
Authors: Infante Smitha K. , Rea Harriett C. , Perez‐Polo J.R.
Published: March 2013

Neonatal hypoxia‐ischemia (HI) affects 60% of low birth weight infants and up to 40% of preterm births. Cell death and brain injury after HI have been shown to cause long‐lasting behavioral deficits. By using a battery of behavioral tests on second generation 3‐week‐old rodents, we found that neonatal HI is associated with behavioral outcomes in the progeny of HI‐affected parents. Our results suggest an epigenetic transfer mechanism of some of the neurological symptoms associated with neonatal HI. Elucidating the transfer of brain injury to the next generation after HI calls attention to the risks associated with HI injury and the need for proper treatment to reverse these effects. Assessing the devastating extent of HI's reach serves as a cautionary tale to the risks associated with neonatal HI, and provides an incentive to create improved therapeutic measures to treat HI.
The Ties that Bind: A Network Analysis of Human Rights International Nongovernmental Organizations
Authors: Murdie Amanda
Published: March 2013

Much scholarship concerning human rights international nongovernmental organizations (HR-INGOs) focuses on the central role they play within transnational advocacy networks. Despite this theoretical focus on networks, there has been scant empirical attention on the characteristics of the HR-INGO network or on whether the network characteristics of a HR-INGO matter for its advocacy output. Introducing a new relational dataset on 681 HR-INGOs, this article finds that the HR-INGO network is somewhat like a public good and that the organizations who utilize it benefit in terms of their international advocacy output. Other findings focus on how the structural characteristics of organizations can influence their propensity to connect to each other and how ‘free-riding’ can limit the benefits organizations receive from the network.
ADDITIVE FUNCTIONAL INEQUALITIES AND DERIVATIONS ON HILBERT C*-MODULES
Authors: MORADLOU FRIDOUN
Published: March 2013

In this paper we investigate the following functional inequality
$
\begin{eqnarray*}
\| f(x-y-z) - f(x-y+z) + f(y) +f(z)\| \leq \|f(x+y-z) - f(x)\|
\end{eqnarray*}$
in Banach spaces, and employing the above inequality we prove the generalized Hyers–Ulam stability of derivations in Hilbert C*-modules.
SOCIAL IDENTITY AND ATTITUDES TOWARD FOREIGN POLICY: EVIDENCE FROM A YOUTH SURVEY IN TURKEY
Authors: Ciftci Sabri
Published: March 2013

This paper focuses on the relationship between social identity based on national, religious, or international affiliations and attitudes toward foreign policy in the Turkish context. Evidence is drawn from an original survey conducted among university students in Turkey. The results show that students' social identity has a significant correlation with their perceptions of foreign policy. Most Turkish university students provide conditional support for the new directions in Turkey's foreign policy, but those with an Islamic identity appear to be more supportive of the Adalet ve Kalkınma Partisi's (Justice and Development Party) policies. Most university students believe that Turkey's future lies in the European Union and the Central Asian Turkic republics rather than in the Middle East. Overall, the perceptions of educated youth toward foreign policy are shaped by both social identity and their conceptions of national interest.
THE RISE OF THE SUBCONTRACTOR STATE: POLITICS OF PSEUDO-PRIVATIZATION IN THE ISLAMIC REPUBLIC OF IRAN
Authors: Harris Kevan
Published: March 2013

Since 2009, analyses of Iran have stressed the centralizing takeover of the country's economy by a single state institution, the Islamic Revolutionary Guards Corps. At the same time, however, Iran's factionalized political elite uniformly advocate for rapid privatization of state-owned enterprises. Underneath this puzzling contradiction is a complex shift of economic ownership away from the state toward a variety of parastatal organizations including banks, cooperatives, pension funds, foundations, and military-linked contractors. The result is not a praetorian monolith but a subcontractor state. This article draws on interviews conducted in Iran during 2009 and 2010, primary data from parliamentary and governmental reports, and secondary sources to show how intraelite conflict and nonelite claims have structured the process of privatization. Framed comparatively with privatization outcomes in other middle-income countries, Iran's subcontractor state can be seen as a consequence of the way in which politics and society shaped the form of capitalism that has taken root in the Islamic Republic.
Locating Afghan History
Authors: Green Nile
Published: March 2013

Afghanistan's 20th century has long been seen through an analytical dichotomy. One concentration of historical scholarship has sought to explain the fraught progress of Afghan nation-building in the 1910s and 1920s. A second has sought to explain the unraveling of the Afghan nation after 1979. Weighted toward the decades at either end of the century, this dichotomized field has been problematic in both chronological (and thereby processual) and methodological terms. On the level of chronology, the missing long mid-section (indeed, half) of the century between the framing coups of 1929 and 1979 has made it difficult to convincingly join together the two bodies of scholarship. Not only has the missing middle further cemented the division of scholarly labor but it also has made it more difficult to connect the history of the last quarter of the century to that of the first quarter (except as a story of parallels), rendering them discrete narratives of development, one ending and the other beginning with a coup. The problems are deeper than this, though, extending from questions of chronology and process to matters of method. For if in its focus on nationalism and nation-building the first-quarter scholarship is framed within the neat boundaries of national spaces and actors, then in its focus on the unraveling of the nation and its peoples through the consequences of Soviet intervention, the last-quarter scholarship elevates nonnational actors as the key agents of historical process.
On Mobility in Afghan History
Authors: McChesney R. D.
Published: March 2013

If we leave aside the imperial histories of those powers for which Afghanistan has been a strategic concern, Afghan historiography has tended to follow a single trajectory: the history of the Pashtuns and their principal royal clan, the Durrani. The non-Pashtun part of the human ecology of the country tends to be summed up as “other groups,” as if that 60 percent of the population only has a history in relation to the royal clan and its state. As the other essays in this roundtable argue, there are many ways to approach Afghanistan's history more inclusively than through Kabul-centric, Pashtun-dominated, top-down narratives or those that focus on the strategic concerns of superpowers. Nile Green sees a half-century gap in the historiography, between the nation-building of the 1920s and the nation-demolishing of the 1990s and beyond, and proposes the study of “subnational and transnational groups” as one way to refine our understanding of the politics of the country during that middle era. James Caron traces an imagined bond with place reflected in rural oral imagery, while Amin Tarzi approaches Afghan historiography itself as a productive field of study. Other areas hardly touched in the existing scholarship are institutional histories (judicial, educational, and fiscal), for which there is a wealth of untapped documentation; the built environment (following the seminal works of Szabo and Barfield on domestic and rural architecture and Schinasi on urban architecture); labor history (including the interconnections of work specializations and industry with ethnic groups); and the history of human bondage in the country.
How Judges Use Weapons of Influence: The Social Psychology of Courts
Authors: Davidov Guy , Davidov Maayan
Published: March 2013

Research on compliance has shown that people can be induced to comply with various requests by using techniques that capitalise on the human tendencies to act consistently and to reciprocate. Thus far this line of research has been applied to interactions between individuals, not to relations between institutions. We argue, however, that similar techniques are applied by courts vis-à-vis the government, the legislature and the public at large, when courts try to secure legitimacy and acceptance of their decisions. We discuss a number of known influence techniques – including ‘foot in the door’, ‘low-balling’, ‘giving a reputation to uphold’ and ‘door in the face’ – and provide examples from Israeli case law of the use of such techniques by courts. This analysis offers new insights that can further the understanding of judicial decision-making processes.
Sex in older age in rural Malawi
Authors: FREEMAN EMILY K. , COAST ERNESTINA
Published: March 2013

This paper examines how older adults living in rural Malawi explain and understand their sex lives. We present sex in this setting as a field in which broader understandings of ageing, aged identities, and conceptions of person- or adulthood in older age are played out and constructed. Qualitative data were collected from men (N=20) and women (N=23) aged 50 to around 90 using in-depth multiple dependent interviews (N=135) between 2008 and 2010. The giving and receipt of sexual pleasure was considered natural and God-given. Primarily understood as a matter of ‘power’, sex was on the one hand, beneficial to older bodies, but on the other, not accessible to such bodies. Declining sexual frequency was associated with declining desire for sex, or frustration stemming from continued desire for sex. These discourses emerged from the way the ageing body was constructed as a weakened body, incompatible with understandings of adulthood based on physical productivity. Older men and women used sex to discursively respond to these challenges to their adulthood in two ways. Firstly, sex was used to confirm strength, physical productivity, and therefore, identity as an ‘adult’. Secondly, adulthood itself was redefined as being based on moral, rather than physical productivity, and refraining from sex was used to demonstrate wisdom, self-control and therefore their ‘adult’ identity. Our results provide in-depth understanding of the ways constructions of ageing and sex can influence complex experiences of marital and non-marital sex in older age. We contribute to debates on sexuality in the gerontological literature by moving discussion beyond the presentation of continued sexuality as somehow exceptional or an indicator of successful ageing. Finally, in a setting of considerable HIV prevalence at older ages, our results challenge a preoccupation with fertility and chronological age in the collection of sexual health data in Africa.
On the International Court of Justice and the Determination of Rules of Law
Authors: VILLALPANDO SANTIAGO
Published: March 2013

In the process of selection of articles for the International Court of Justice section at the Editorial Board of the Leiden Journal of International Law (LJIL), we tend to be seduced by those manuscripts which are effective in making use of the jurisprudence of the Court as an instrument to engage in an in-depth examination of substantive legal issues of a general nature. This reflects our conviction – hardly an original one, since it appears to be shared by our entire legal community – that the Court has a fundamental role to play in the advancement of international law as a legal system. It also echoes an idea that is present in the mission statement of our journal, which is conceived as ‘a forum for two vital areas, namely international legal theory and international dispute settlement’, thus establishing an intrinsic link between them. But how is the Court's contribution to the development of international law to be assessed? And what do we expect from a scholarly piece examining its case law in this respect?
Elevated troponin levels in previously healthy children: value of diagnostic modalities and the importance of a drug screen
Authors: Thankavel Poonam P. , Mir Arshid , Ramaciotti Claudio
Published: March 2013

Background:Myocardial injury in previously healthy children is rare, with a wide range of aetiologies. It is increasingly being identified on the basis of elevated troponin levels during routine evaluation of cardiorespiratory symptoms. Establishing the aetiology remains challenging because of the lack of an accepted work-up algorithm. Our objective was to delineate the contribution of diagnostic modalities and troponin patterns towards the final diagnosis.Methods:A retrospective chart review of previously healthy patients admitted to the Pediatric Cardiology Service with myocardial injury was carried out. Data analysed included echocardiograms, electrocardiograms, cardiac catheterisations, magnetic resonance imaging, drug screen tests, troponin values, and final diagnosis.Results: A total of 32 patients were identified. The diagnoses were: myocarditis in 16 patients, vasospasm due to drug use in seven, myopericarditis in six, anomalous coronary artery origins in two, and Prinzmetal's angina in one patient. The electrocardiograms were abnormal in 27 of the 32 patients (84%), echocardiograms in 18 of the 32 patients (56%), cardiac magnetic resonance imaging in two of the four patients (50%), urine drug screen in five of the 25 patients (20%), and cardiac catheterisations in two of the 15 patients (13%).Conclusions: Myocarditis is the most common aetiology of myocardial injury in children. Clinical history remains the basic screening tool; drug screens help identify coronary vasospasms secondary to drug use (22% of our cohort). Patients with anomalous coronaries had exertional symptoms. Initial troponin levels and progression were not diagnostic or prognostic. Catheterisation is of limited value and did not change management. Magnetic resonance imaging with gadolinium enhancement is probably the most useful test when initial evaluation is not diagnostic.
Pre-operative identification of an anomalous left coronary artery from the pulmonary artery in association with tetralogy of Fallot and an aortopulmonary window
Authors: McMahon Colin J. , Prendiville Terence , Nolke Lars
Published: March 2013

A newborn baby girl was diagnosed with tetralogy of Fallot and an aortopulmonary window. At 3 weeks of age, the coexistent diagnosis of an anomalous left coronary artery from the pulmonary artery was made. Initial surgical intervention included a Takeuchi baffle of the left coronary artery, closure of the aortopulmonary window, and placement of a right Blalock–Taussig shunt. Complete repair was undertaken at 12 months of age. Close pre-operative assessment of the coronary arterial anomaly is crucial in patients with an aortopulmonary window and tetralogy of Fallot.
Development of a Functional Analytical Nurse Observation Chart (FANOC)
Authors: Veale David , Warlow Selina , O'Donoghue Tara , Callow Chris
Published: March 2013

Background: There has been little evaluation or development of nurse observation charts on psychiatric in-patient units since they were first introduced. Aim: We aimed to develop a new nursing chart that adds a functional and contextual assessment of the observed behaviour. We describe its initial evaluation in an in-patient setting. Method: A member of the staff coded a participant's behaviour as either an instance of an individual's daily life problem; or an improvement; or a non-clinically relevant behaviour. We evaluated the charts in 14 in-patients and compared the coding of the behaviour against that of one of the investigators. Results: After brief training the inter-rater agreement resulted in Kappa = 0.496 with p < .001. Removal of a rating of neutral behaviours resulted in a higher Kappa = 0.546 with p < .001. Conclusions: The inter-rater reliability was only moderate for the Functional Analytical Nurse Observation Charts. Frequent training and support from management and therapy staff is required to maintain a psychologically informed environment and observation in an in-patient setting. An area for further research is to explore the impact that a FANOC has on staff satisfaction and an individual's experience of care, and whether it can assist in determining mediators of change before an improvement in symptoms.
Depth of -singularities and base change of relative canonical sheaves
Authors: Patakfalvi Zsolt , Schwede Karl
Published: March 2013

For a characteristic-$p\gt 0$variety$X$with controlled$F$-singularities, we state conditions which imply that a divisorial sheaf is Cohen–Macaulay or at least has depth$\geq $3 at certain points. This mirrors results of Kollár for varieties in characteristic 0. As an application, we show that relative canonical sheaves are compatible with arbitrary base change for certain families with sharply$F$-pure fibers.
Defining and measuring party system nationalization
Authors: Lago Ignacio , Montero José Ramón
Published: March 2013

In this paper, we propose a new measure of party system nationalization based on a minimalist definition of the phenomenon. A perfectly nationalized party system is a party system with only national parties or, in other words, without sub-national parties. Instead of the homogeneity of parties’ vote shares or the number of parties throughout the country, our measure captures the aspirations of parties to be national whose proxy is the proportion of districts (weighted by seats) that a party runs a candidate. The measure is compared with existing indicators through a longitudinal analysis of 256 elections in 18 Western European countries from 1945 to 1998.
Traumagedächtnis bei Kindern mit Posttraumatischer Belastungsstörung
Authors: Lorenz Elvira
Published: March 2013

Das Gedächtnis spielt eine wichtige Rolle bei der Entstehung und Behandlung von Posttraumatischer Belastungsstörung (PTBS). Die vorliegende Überblicksarbeit beschäftigt sich mit der Frage nach dem empirischen Nachweis von traumabezogenen Gedächtnisstörungen im Kindesalter. Die bisherigen Untersuchungen zeigen ein heterogenes Bild. Es gibt Hinweise auf eine Beeinträchtigung der Hirnreifungsprozesse sowie der Erinnerungsqualität bei Kindern und Jugendlichen mit PTBS. Jedoch im Gegensatz zu Befunden im Erwachsenenalter wiesen traumatisierte Kinder ein größeres Hippocampusvolumen im Vergleich zur Kontrollgruppe auf. Die Zusammenschau der Befunde macht den großen Bedarf an weiterführenden Untersuchungen deutlich.
Robust stability criterion of fractional‐order functions for interval fractional‐order systems
Authors: Gao Zhe , Liao Xiaozhong
Published: March 2013

This study presents a sufficient and necessary stability condition for the stability of interval fractional‐order systems. An effective constructive method of the value set on the disturbance function of an interval fractional‐order system is investigated to reduce the burden of computations for the redundant vertices and edges. Based on the zero exclusion principle, a test function and terminal conditions are proposed to verify the stability of interval fractional‐order systems. Finally, a numerical example is given to illustrate the effectiveness of this proposed stability theorem.
Design and experimentation of acceleration‐level drift‐free scheme aided by two recurrent neural networks
Authors: Zhang Zhijun , Zhang Yunong
Published: March 2013

To solve the joint‐angle and joint‐velocity drift problems in cyclic motion of redundant robot manipulators, an acceleration‐level drift‐free (ALDF) scheme subject to a linear equality constraint is proposed, of which the effectiveness is analysed and proved via the theory of second‐order system. The scheme is then reformulated into a quadratic program (QP). Furthermore, two recurrent neural networks (RNNs) are developed for solving the resultant QP problem. The first RNN solver is based on Zhang et al's neural‐dynamic method and called Zhang neural network (ZNN), whereas the other is based on the gradient‐descent method and called gradient neural network (GNN). Comparison results based on computer simulations between the ZNN and GNN solvers with a circular‐path tracking task demonstrate that the ZNN solver has faster convergence and fewer errors. In addition, the hardware experiments of tracking a straight‐line path and a rhombic path based on a six degrees of freedom manipulator validate the physical realisability and efficacy of the proposed ALDF scheme and the two RNN QP‐solvers. Moreover, the position, velocity and acceleration error analyses indicate the accuracy of the proposed ALDF scheme and the corresponding RNN QP‐solvers.
Adaptive boundary control for flexible two‐link manipulator based on partial differential equation dynamic model
Authors: Zhang Linjun , Liu Jinkun
Published: March 2013

In this studies, adaptive boundary control for a flexible two‐link manipulator with a changeable payload at the free‐end. Taking into account the infinite‐dimensionality of the flexural dynamics, this study proposes a partial differential equation (PDE) model, so that the problem of possible spillover instability caused by the neglect of flexible modes can be avoided. Based on the PDE model, an adaptive boundary control scheme is designed to regulate joint position and suppress elastic vibration while compensating for parametric uncertainties. The asymptotic stability of the closed‐loop system is validated theoretically. The effectiveness of the control scheme is also verified by the numerical simulations.
Fault diagnosis and fault‐tolerant control for non‐Gaussian non‐linear stochastic systems using a rational square‐root approximation model
Authors: Yao Lina , Qin Jifeng , Wang Aiping , Wang Hong
Published: March 2013

The purpose of the fault detection and diagnosis of stochastic distribution control systems is to use the measured input and the system output probability density functions (PDFs) to obtain the fault information of the system. In this paper, the rational square‐root B‐spline model is used to represent the dynamics between the output PDF and the input. This is then followed by the novel design of a non‐linear neural network observer‐based fault diagnosis (FD) algorithm so as to diagnose the fault in the dynamic part of such systems. Convergency analysis is performed for the error dynamic system raised from the fault detection and diagnosis phase using the Lyapunov stability theorem. Finally, based on the FD information, a new fault‐tolerant control based on proportional integral tracking control scheme is designed to make the post‐fault PDF still track the given distribution. A simulated example is given to illustrate the efficiency of the proposed algorithms.
Dead‐time compensation of constrained linear systems with bounded disturbances: output feedback case
Authors: Santos Tito L. M. , Limon Daniel , Normey‐Rico Julio E. , Raffo Guilherme V.
Published: March 2013

This study presents an analysis about state estimation and dead‐time compensation effect over constrained control systems with bounded disturbances and dead‐time. It is shown that input‐to‐state stability and constraint satisfaction can be guaranteed by using an equivalent dead‐time free system with measurable states and modified disturbances. This result may be useful to simplify synthesis and analysis of a given constrained control strategy. A linear output feedback control scheme and a tube‐based model predictive control strategy are used as motivating examples.
On the interactions between poly(ethylene oxide) and graphite oxide: A comparative study by different computational methods
Authors: Garcia-Yoldi I. , Álvarez F. , Colmenero J.
Published: March 2013

The aim of this work is to investigate polymer···substrate interactions for a polymer nanocomposite material: poly(ethylene oxide) (PEO) confined in graphite oxide (GO). Six discrete and simplified models (one for PEO and five for GO) have been chosen in order to reproduce the most likely PEO···GO interactions. Twelve potential interaction energy curves have been built using the models and curve minima have been optimized using the 2nd order Møller-Plesset perturbation theory (MP2)/6-31+G(d) method. The intermolecular interactions have been analyzed in terms of distances, stabilities, and bond critical points properties revealing several dispersion assisted π-interactions and the most stable hydrogen bond interaction between the hydrogen of the GO hydroxyl groups and the oxygen of the PEO. MP2 results have been compared with five density functionals developed by Truhlar and Zhao (M05, M05-2X, M05-2X, M06-HF, and M06-L).
Double-sided tin nanowire arrays for advanced thermal interface materials
Authors: Feng Bo , Faruque Fardin , Bao Peng , Chien An-Ting , Kumar Satish , Peterson G. P.
Published: March 2013

This investigation examines a type of thermal interface material (TIM) based on a double-sided array of tin nanowires (NWs) prepared using a hot-pressing approach with the assistance of anodic aluminum oxide templates. The metal based TIM effectively reduces the contact resistance, while the flexible nanowires show excellent mechanical compliance to increase the actual contact area with the mating rough surfaces. The results indicate that the overall thermal contact resistance of the two rough copper surfaces assisted by the tin NW array, can reduce the overall resistance to 29 mm2KW-1 at 0.25 MPa and 20 mm2KW-1 at 1.0 MPa.
Theoretical reconstruction of realistic dynamics of highly coarse-grainedcis-1,4-polybutadiene melts
Authors: Lyubimov I. Y. , Guenza M. G.
Published: March 2013

The theory to reconstruct the atomistic-level chain diffusion from the accelerated dynamics that is measured in mesoscale simulations of the coarse-grained system, is applied here to the dynamics of cis-1,4-polybutadiene melts where each chain is described as a soft interacting colloidal particle. The rescaling formalism accounts for the corrections in the dynamics due to the change in entropy and the change in friction that are a consequence of the coarse-graining procedure. By including these two corrections the dynamics is rescaled to reproduce the realistic dynamics of the system described at the atomistic level. The rescaled diffusion coefficient obtained from mesoscale simulations of coarse-grained cis-1,4-polybutadiene melts shows good agreement with data from united atom simulations performed by Tsolou et al. [Macromolecules 38, 1478 (2005)]10.1021/ma0491210. The derived monomer friction coefficient is used as an input to the theory for cooperative dynamics that describes the internal dynamics of a polymer moving in a transient regions of slow cooperative motion in a liquid of macromolecules. Theoretically predicted time correlation functions show good agreement with simulations in the whole range of length and time scales in which data are available.
Influence of trap location on the efficiency of trapping in dendrimers and regular hyperbranched polymers
Authors: Lin Yuan , Zhang Zhongzhi
Published: March 2013

The trapping process in polymer systems constitutes a fundamental mechanism for various other dynamical processes taking place in these systems. In this paper, we study the trapping problem in two representative polymer networks, Cayley trees and Vicsek fractals, which separately model dendrimers and regular hyperbranched polymers. Our goal is to explore the impact of trap location on the efficiency of trapping in these two important polymer systems, with the efficiency being measured by the average trapping time (ATT) that is the average of source-to-trap mean first-passage time over every staring point in the whole networks. For Cayley trees, we derive an exact analytic formula for the ATT to an arbitrary trap node, based on which we further obtain the explicit expression of ATT for the case that the trap is uniformly distributed. For Vicsek fractals, we provide the closed-form solution for ATT to a peripheral node farthest from the central node, as well as the numerical solutions for the case when the trap is placed on other nodes. Moreover, we derive the exact formula for the ATT corresponding to the trapping problem when the trap has a uniform distribution over all nodes. Our results show that the influence of trap location on the trapping efficiency is completely different for the two polymer networks. In Cayley trees, the leading scaling of ATT increases with the shortest distance between the trap and the central node, implying that trap's position has an essential impact on the trapping efficiency; while in Vicsek fractals, the effect of location of the trap is negligible, since the dominant behavior of ATT is identical, respective of the location where the trap is placed. We also present that for all cases of trapping problems being studied, the trapping process is more efficient in Cayley trees than in Vicsek fractals. We demonstrate that all differences related to trapping in the two polymer systems are rooted in their underlying topological structures.
Surface-sensitive conductivity measurement using a micro multi-point probe approach
Authors: Perkins Edward , Barreto Lucas , Wells Justin , Hofmann Philip
Published: March 2013

An instrument for microscale electrical transport measurements in ultra-high vacuum is presented. The setup is constructed around collinear lithographically-created multi-point probes with a contact spacing down to 500 nm. Most commonly, twelve-point probes are used. These probes are approached to the surface via piezoelectric positioners. Standard four-point resistance measurements can be performed using any combination of contacts out of the twelve available. Current/voltage measurements are taken semi-automatically for a variety of the possible contact configurations, effectively emulating measurements with an equidistant four-point probe for a wide range of contact spacings. In this way, it is possible to distinguish between bulk-like and surface-like conduction. The paper describes the design of the instrument and the approach to data and error analysis. Application examples are given for epitaxial graphene on SiC and degenerately doped Bi2Se3.
Inversion-channel GaAs(100) metal-oxide-semiconductor field-effect-transistors using molecular beam deposited Al2O3 as a gate dielectric on different reconstructed surfaces
Authors: Chang Y. C. , Chang W. H. , Merckling C. , Kwo J. , Hong M.
Published: March 2013

Inversion-channel metal-oxide-semiconductor field-effect-transistors (MOSFETs) have been fabricated using in-situ molecular beam deposited Al2O3 as a gate dielectric directly on freshly molecular beam epitaxy grown Ga-stabilized (4 × 6) and As-covered c(4 × 4) GaAs(100) reconstructed surfaces. The MOSFET using the former surface gives a drain current (Id) of 92 μA/μm and a transconductance (Gm) of 43 μS/μm in an 1 μm gate length configuration; these values are more than 100 times higher than those attained in the MOSFET using the latter surface, which has an Id of 0.47 μA/μm and a Gm of 0.45 μS/μm. The enhancement of the inversion currents and Gm may indicate Fermi-level unpinning at the oxide/GaAs(100) interface. The result further confirms that the mid-gap interfacial trap densities of 2 × 1012 eV−1 cm−2 and of exceeding 1013 eV−1cm−2 in the samples on the Ga-stabilized and the As-covered GaAs(100) surfaces, respectively, are correlated to the inversion-channel device performance.
Capturing molten globule state of α-lactalbumin through constant pH molecular dynamics simulations
Authors: Bhattacharjee Nicholus , Rani Pooja , Biswas Parbati
Published: March 2013

The recently developed methods of constant pH molecular dynamics directly captures the correlation between protonation and conformation to probe protein structure, function, and dynamics. In this work, we investigate the effect of pH on the conformational properties of the protein human α-lactalbumin. Constant pH simulations at both acidic and alkaline medium indicate the formation of the molten globule state, which is in accordance with the previous experimental observations (especially, in acidic medium). The size of the protein measured by its radius of gyration (RG) exhibits a marked increase in both acidic and alkaline medium, which matches with the corresponding experimentally observed value of RG found in the molten globule. The probability of native contacts is also considerably reduced at acidic and basic pH as compared to that of native structure crystallized at neutral pH. The mean fractal dimension D2 of the protein records a sharp increase in basic medium as compared to those in neutral and acidic solutions implying a significant pH induced conformational change. The mean square fluctuations of all residues of the entire protein are found to increase by several folds in both acidic and basic medium, which may be correlated with the normalized solvent accessibility of the residues indicating role of solvent accessible surface area on protein internal dynamics. The helices comprising the α-domain of the protein are moderately preserved in the acidic and alkaline pH. However, the β-sheet structures present in the β-domain are completely disrupted in both acidic as well as basic pH.
Modeling of localized reflow in solder/magnetic nanocomposites for area-array packaging
Authors: Xu Siyang , Pickel Andrea D. , Prasitthipayong Anya , Habib Ashfaque H. , McHenry Michael E.
Published: March 2013

We have modeled the reflow process of FeCo magnetic nanoparticle (MNP)-based solder composites with eddy current power loss of substrate and magnetic power losses of solder bumps. For an area array package without MNPs when subjected to 300 kHz ac magnetic field, the eddy current power loss can result in excessive temperatures that can cause substrate damage. Temperature profiles with different MNP concentration were simulated and the results showed localized reflow of solders to enable low-temperature assembly. The temperatures at different times and positions in solder composites were analyzed. We also modeled thermal profiles for solder composites with 0.2 wt. % MNP in 1 MHz and 3 MHz magnetic field. Such high field frequency generated larger power losses in MNPs and is shown to increase the heating efficiency.
Controlling crystal self-assembly using a real-time feedback scheme
Authors: Klotsa Daphne , Jack Robert L.
Published: March 2013

We simulate crystallisation of hard spheres with short-ranged attractive potentials as a model self-assembling system. Using measurements of correlation and response functions, we develop a method whereby the interaction parameters between the particles are automatically tuned during the assembly process, in order to obtain high-quality crystals and avoid kinetic traps. The method we use is independent of the details of the interaction potential and of the structure of the final crystal—we propose that it can be applied to a wide range of self-assembling systems.
Disagreement between theory and experiment grows with increasing rotational excitation of HD(v′, j
′) product for the H + D2 reaction
Authors: Jankunas Justin , Sneha Mahima , Zare Richard N. , Bouakline Foudhil , Althorpe Stuart C.
Published: March 2013

The Photoloc technique has been employed to measure the state-resolved differential cross sections of the HD(v′, j′) product in the reaction H + D2 over a wide range of collision energies and internal states. The experimental results were compared with fully dimensional, time-dependent quantum mechanical calculations on the refined Boothroyd-Keogh-Martin-Peterson potential energy surface. We find nearly perfect agreement between theory and experiment for HD(v′, j′) product states with low to medium rotational excitation, e.g., HD(v′ = 1, j′ = 3) at a collision energy, Ecoll, of 1.72 eV, HD(v′ = 1, j′ = 3, 5) at Ecoll = 1.97 eV, and HD(v′ = 3, j′ = 3) at Ecoll = 1.97 eV. As the rotational angular momentum, j′, of HD(v′, j′) increases, the agreement between theoretical predictions and experimental measurements worsens but not in a simple fashion. A moderate disagreement between theory and experiment has been found for HD(v′ = 0, j′ = 12) at Ecoll = 1.76 eV and increased monotonically for HD(v′ = 0, j′ = 13) at Ecoll = 1.74 eV, HD(v′ = 0, j′ = 14) at Ecoll = 1.72 eV, and HD(v′ = 0, j′ = 15) at Ecoll = 1.70 eV. Disagreement was not limited to vibrationless HD(v′, j′) product states: HD(v′ = 1, j′ = 12) at Ecoll = 1.60 eV and HD(v′ = 3, j′ = 8, 10) at Ecoll = 1.97 eV followed a similar trend. Theoretical calculations suggest more sideways/forward scattering than has been observed experimentally for high j′ HD(v′, j′) states. The source of this discrepancy is presently unknown but might be the result of inaccuracy in the potential energy surface.
Ferrofluid droplet heating and vaporization under very large magnetic power: A thermal boundary layer model
Authors: Cristaldo C. F. C. , Fachini F. F.
Published: March 2013

In this work, heating and vaporization of a liquid droplet with dispersed magnetic nanoparticles (ferrofluid) are analyzed. The ferrofluid droplet is in a quiescent inert gas phase with a temperature which is set down equal to, higher and lower than the liquid boiling temperature. Under these conditions, an alternating magnetic field is applied and, as a result, the magnetic nanoparticles generate heat by the Brownian relaxation mechanism. In this mechanism, the magnetic dipoles present a random orientation due to collisions between the fluid molecules and nanoparticles. The magnetic dipoles tend to align to the magnetic field causing rotation of the nanoparticles. Consequently the temperature increases due to the energy dissipated by the friction between the resting fluid and the rotating nanoparticles. Assuming a very large magnetic power and a uniform distribution of nanoparticles, the droplet core is uniformly heated. A thermal boundary layer is established in the liquid-phase adjacent to the droplet surface due to heat flux from the ambient atmosphere. The temperature profile inside the thermal boundary layer is obtained in appropriate time and length scales. In the present model, the ferrofluid droplet is heated up to its boiling temperature in a very short time. In addition, the combination of the heat generated by magnetic nanoparticles and heat conduction from gas phase results in a higher vaporization rate. Under specific conditions, the boiling temperature is achieved not at the surface but inside the thermal boundary layer. Moreover, the results point out that the thermal boundary layer depends directly on the vapor Lewis number but the vaporization rate reciprocally on it.
Generalized model of the dielectric function of AlInGaP alloys
Authors: Turcotte S. , Daraselia M.
Published: March 2013

Optical phenomena affecting the performance of (AlxGa1−x)0.52In0.48P based optoelectronic devices, such as solar cells and light emitting diodes, depend critically on the determination of the optical constants of these alloys throughout their compositional range. In this work, a generalization of the description of the dielectric function of (AlxGa1−x)0.52In0.48P alloys as a function of the Al composition x is obtained for 0.052 < x < 1, over the energy range of 1.25–5 eV. By comparison to previous approaches used to describe the dielectric function of AlInGaP alloys, the parametric model of Johs et al. [Thin Solid Films 313–314, 137 (1998)] represents a generalization of previous models, being fully Kramers-Kronig consistent and flexible enough to describe the non-parabolic behavior of the joint density of states away from given critical points of the Brillouin zone. It also matches our experimental data for the absorption coefficient below the fundamental band edge. The results suggest that part of the states originating from the L region of the Brillouin zone become available at Γ, leading to a decrease and an increase of the oscillator strengths of the E1 and E0 transitions, respectively. In addition, it is found that the contributions of indirect transitions from the X point of the Brillouin zone can be neglected as the vertical transitions largely dominate the description of the dielectric function of such alloys.
An exact solution of the linearized Boltzmann transport equation and its application to mobility calculations in graphene bilayers
Authors: Paussa A. , Esseni D.
Published: March 2013

This paper revisits the problem of the linearized Boltzmann transport equation (BTE), or, equivalently, of the momentum relaxation time, momentum relaxation time (MRT), for the calculation of low field mobility, which in previous works has been almost universally solved in approximated forms. We propose an energy driven discretization method that allows an exact determination of the relaxation time by solving a linear, algebraic problem, where multiple scattering mechanisms are naturally accounted for by adding the corresponding scattering rates before the calculation of the MRT, and without resorting to the semi-empirical Matthiessen's rule for the relaxation times. The application of our rigorous solution of the linearized BTE to a graphene bilayer reveals that, for a non monotonic energy relation, the relaxation time can legitimately take negative values with no unphysical implications. We finally compare the mobility calculations provided by an exact solution of the MRT problem with the results obtained with some of the approximations most frequently employed in the literature and so discuss their accuracy.
First principle structural determination of (B2O3)n (n = 1–6) clusters: From planar to cage
Authors: Li Lifen , Cheng Longjiu
Published: March 2013

The structure of (B2O3)n clusters (n = 1–6) are investigated using the method combining the genetic algorithm with density functional theory. Benchmark calculations indicate that TPSSh functional is reliable in predicting the energetic sequences of different isomers of (B2O3)n cluster compared to the high-level coupled cluster method. The global minimum (GM) structures of (B2O3)n clusters are planar up to n = 3, and cages at n = 4–6. A Td fullerene is found in the GM structure at n = 6. The stability of three-dimensional structures increases with the size of the cluster according to the analysis of the calculated atomization energy. Natural bonding analysis given by adaptive natural density partitioning reveals delocalized π-bonding in the 4-membered and 6-membered rings, and it is aromatic at the centers of cages and rings.
Streaked radiography of an irradiated foam sample on the National Ignition Facility
Authors: Cooper A. B. R. , Schneider M. B. , MacLaren S. A. , Moore A. S. , Young P. E. , Hsing W. W. , Seugling R. , Foord M. E. , Sain J. D. , May M. J. , Marrs R. E. , Maddox B. R. , Lu K. , Dodson K. , Smalyuk V. , Graham P. , Foster J. M. , Back C. A. , Hund J. F.
Published: March 2013

Streaked x-ray radiography images of annular patterns in an evolving tantalum oxide foam under the influence of a driven, subsonic radiation wave were obtained on the National Ignition Facility. This is the first successful radiography measurement of the evolution of well-defined foam features under a driven, subsonic wave in the diffusive regime. A continuous record of the evolution was recorded on an x-ray streak camera, using a slot-apertured point-projection backlighter with an 8 ns nickel source (7.9 keV). Radiography images were obtained for four different annular patterns, which were corrected using a source-dependent flat-field image. The evolution of the foam features was well-modeled using the 3D KULL radiation hydrodynamics code. This experimental and modeling platform can be modified for scaled high-energy-density laboratory astrophysics experiments.
Investigation of the origin of glassiness in La0.5Sr0.5CoO3
Authors: Manna Kaustuv , Elizabeth Suja , Anil Kumar P. S.
Published: March 2013

A comprehensive magnetic study has been carried out on the two sets of La0.5Sr0.5CoO3 samples with a view to understand the origin of low temperature glassiness in the ferromagnetic state. The samples prepared by the conventional solid-state synthesis method show a low temperature shoulder in both dc magnetization as well as in the ac susceptibility measurements, which exhibit characteristics of glassiness such as the frequency dependence and memory effect. These observations suggest the existence of a distinct low temperature cluster-glass like phase within dominant ferromagnetic phase. But, once the same sample is properly homogenized by repeated grinding and annealing process, the low temperature glassy phase disappears, and it shows a pure ferromagnetic behavior. Our comparative study clearly reveals that the reentrant spin-glass like nature is not intrinsic to La0.5Sr0.5CoO3 system, in fact this is an outcome of the compositional inhomogeneity.