bluuebunny/crossref_metadata_2025 huggingface dataset:
Intervertebral Disk Repair by Protein, Gene, or Cell Injection: A Framework for Rehabilitation‐Focused Biologics in the Spine
Authors: Zhang Yejia , Chee Ana , Thonar Eugene J.‐M.A. , An Howard S.
Published: June 2011

Low back pain carries an enormous socioeconomic burden. Current treatment modalities for symptomatic intervertebral disk (IVD) degeneration have limited and often inconsistent clinical benefits. Novel approaches with the potential to halt or even reverse disk degeneration and restore physiologic disk function, such as biological treatments, are therefore very attractive. The following barriers are impeding the development of successful therapeutic interventions: (1) the biology and pathophysiology of disk degeneration are not well understood, and (2) the precise relationship between IVD degeneration and low back pain remains unclear. This article reviews the structural changes that take place during IVD degeneration and their relationship to diskogenic back pain. It also presents treatment modalities that currently are under laboratory investigation and are being studied in clinical trials. The authors of recent studies have shown that the content of large proteoglycans, such as aggrecan and versican, decreases with aging and IVD degeneration, whereas the content of certain small proteoglycans, such as biglycan, increases. Proinflammatory cytokines such as interleukin‐1 and tumor necrosis factor‐α also are associated with IVD degeneration and are potential biomarkers of IVD degeneration and repair. Our group of investigators and others have developed in vitro models of IVD cell and explant culture in addition to in vivo animal models to study IVD degeneration and repair. With the use of these models, we have tested candidate therapeutic agents to assess their therapeutic potential for matrix restoration. When a rabbit annular puncture model of IVD degeneration was used, injections of either bone morphogenetic protein‐7 (also known as osteogenic protein‐1) or bone morphogenetic protein‐14 (also known as growth differentiation factor‐5) were shown to be effective in restoring IVD structures. On the basis of these data, the Food and Drug Administration has recently allowed the initiation of Investigational New Drug clinical trials on osteogenic protein‐1 and growth differentiation factor‐5 in the United States. Protein therapies such as other growth factors, inhibitors of degradation enzymes or cytokines, and cell therapies also are being investigated in laboratory settings with the goal of restoring disk function and alleviating back pain symptoms. These therapies may be used by physiatrists with the skills required to administer intradiskal injections and supervise a comprehensive rehabilitation program after the procedures. Ultimately, the clinical use of any biological treatment discussed in this article would require the collective efforts of clinicians and researchers.
Biomarker Development for Musculoskeletal Diseases
Authors: Huang Wan , Sowa Gwendolyn
Published: June 2011

More than one in 4 Americans has a musculoskeletal (MSK) disorder that requires medical diagnosis and treatment. Imaging tools are able to demonstrate structural changes but cannot reflect the disease activity or symptom severity of MSK conditions. This is of paramount concern in the aging population, in which imaging findings have poor correlation with symptoms, and multiple pain generators frequently coexist. Because levels of inflammatory and matrix breakdown products address disease activity, evaluation of biomarkers has the potential to provide assessment of active pain generators above and beyond the changes observable on imaging studies. This fact has stimulated research interest in the search for novel biomarkers of disease activity and response to treatment in body fluids. The goal is to develop panels of multi‐biomarkers, which could be used independently or in conjunction with the imaging tools, for the diagnosis, prognosis, and treatment validation in MSK diseases. The current review of MSK biomarkers is organized into 3 mechanistic categories: the metabolites of extracellular matrix of MSK tissues; inflammatory cytokines and chemokines; and pain‐related neuropeptides and/or chemicals. Although some representative biomarkers could be used alone, the fact that MSK diseases are multi‐tissue disorders that involve the muscles, bones, cartilage, and nerves suggests that panels of biomarkers may have greater potential than any single biomarker used in isolation. As advances in biotechnology make this a reality, multi‐biomarker panels that include all 3 categories of biomarkers, used either alone or in combination with imaging tools, has the potential to revolutionize the clinical approach to MSK diseases.
Biological Basis of Exercise‐Based Treatments for Musculoskeletal Conditions
Authors: Ambrosio Fabrisia , Tarabishy Ayman , Kadi Fawzi , Brown Elke H.P. , Sowa Gwendolyn
Published: June 2011

Exercise‐based therapies are the cornerstone of rehabilitation programs. While the benefits of exercise on systemic and tissue function are generally accepted, mechanisms underlying these benefits are sometimes poorly understood. An improved understanding of the effects of mechanical loading on molecular and cellular processes has the potential to lead to more disease‐specific and efficacious exercise‐based therapies. The purpose of this paper is to review the current literature examining the role of mechanical signaling on muscle and cartilage biology.
Identifying Inflammatory Targets for Biologic Therapies for Spine Pain
Authors: Jacobs Lloydine J. , Vo Nam , Kang James D.
Published: June 2011

The costs associated with treating spine‐related conditions are enormous and are trending upward. Current methods employed to treat inflammatory‐mediated pain are targeted at alleviating symptoms, rather than correcting the underlying cause of disease. It is clear that a biochemical basis for inflammatory‐mediated intervertebral disk, facet joint, and nerve pain exists. Biologic therapies that address the underlying cause of pain could potentially decrease the costs associated with treating spine pathology. MMPs, IL‐1, TNF‐ α, IL‐6, NGF, bradykinin, prostaglandins, and nitric oxide are implicated in much of the catabolic effects seen in the pathogenesis of inflammatory‐mediated pain and are good targets for inhibition. The anticatabolic and anabolic effects of TIMPs, BMPs, TGF‐ β, and IGF‐1 are targets already shown to favorably impact disk matrix homeostasis. With rapid advances in biomedical technology, these interventions may be available for clinical use in the near future.
Testing IT
Authors: Watkins John , Mills Simon
Published: June 2011

Testing IT provides a complete, off-the-shelf software testing process framework for any testing practitioner who is looking to research, implement, roll out, adopt, and maintain a software testing process. It covers all aspects of testing for software developed or modified in-house, modified or extended legacy systems, and software developed by a third party. Software professionals can customize the framework to match the testing requirements of any organization, and six real-world testing case studies are provided to show how other organizations have done this. Packed with a series of real-world case studies, the book also provides a comprehensive set of downloadable testing document templates, proformas, and checklists to support the process of customizing. This new edition demonstrates the role and use of agile testing best practices and includes a specific agile case study.
TranslatingDharma: Scottish Missionary-Orientalists and the Politics of Religious Understanding in Nineteenth-Century Bombay
Authors: Numark Mitch
Published: June 2011

A consideration of colonial Bombay enriches the understanding of the activities and ideas of Christian missionaries and Orientalists in India and elucidates British conceptions of “the religions of India” and the production of colonialist knowledge. This article focuses on nineteenth-century Scottish missionary-Orientalists and examines how they and other Bombay-based Protestant missionaries understood the concept of religion, Christianity, and the structure, similitude and distinctiveness of “the religions” at the crucial moment when newly “discovered” religions were gaining recognition and a new vision of “world religions” was coming into being. It considers the writings on the religions and ethnographic scholarship of the Bombay Scottish missionaries, as well as their extensive and multifaceted interactions with Bombay's Hindu, Muslim, Jain, Parsi, Jewish, Roman Catholic and Andivasi communities. More specifically, it details the ways in which Bombay missionaries applied and related the concept of religion to diverse configurations of language, text, and practice that they understood as isomorphic species of the religion genus. By examining how Christian missionaries who were also Orientalists conceptualized a number of “religions” and interacted with numerous communities this article seeks to elucidate the presuppositions that shaped the ways in which Hinduism and the other “religions” of nineteenth-century Bombay were imagined.
Korea on the Brink: Reading theYŏnp'yŏngShelling and its Aftermath
Authors: Kim Nan
Published: June 2011

By late December 2010, the truculence of brinkmanship between the two Koreas made it easy to forget that more auspicious signs of compromise had come as recently as this past autumn. The resumption of reunions among separated Korean families in late October and early November appeared to signal a modest improvement in inter-Korean cooperation, raising hopes that a program of cross-border family meetings would not only continue, but also expand. Yet, those hopes were dashed only weeks later when a military crisis escalated off the west coast of the Korean peninsula. On November 23 in a contested maritime zone, a South Korean military exercise was challenged by a North Korean artillery unit, which escalated the confrontation by shelling a South Korean island—killing four South Koreans including two civilians. In the artillery exchange that followed between the two sides, five North Korean soldiers were killed. The stark contrast between the pathos of the tearful family reunions and the panic and anger following the shelling of Yŏnp'yŏng Island, illustrated how quickly the inter-Korean situation had deteriorated. During the same month when South Korea hosted world leaders at the G-20 summit in Seoul to discuss the state of the global economy and the risks of a brewing “currency war,” the family reunions and deadly artillery attack served as sobering reminders that the Korean War, never formally ended, still continues.
Is Every Action Morally Significant?
Authors: Haldane John
Published: June 2011

One form of scepticism about the possibility ofmoral theorydoes not deny that there is something describable as ‘the conduct of life’, but it argues that there is no special ethical account to be given of this since conduct has no identifiablymoraldimension. Here I explore the possibility that the problem of identifying distinctively moral aspects of action is explained by the thesis that the moral is ubiquitous; thateveryhuman actionis– not ‘may be’ – morally significant. To say, however, that morality is all pervasive is not to say anything about howdemandingmoral considerations may be. Reasons for action ultimately relate to promoting or protecting the human good, and their relative strength and urgency derives from the manner, extent and immediacy of their bearing upon this end and not from belonging to some logically distinct category.
From Idealism to Pragmatism: India and Asian Regional Integration
Authors: JAIN RAJENDRA K.
Published: June 2011

After being at the periphery for decades, India's proactive engagement with East and Southeast Asia has gradually transformed it into an active participant in Asian regional organizations and multilateral processes. This paper examines early Indian attempts at forging pan-Asian unity and assesses the motivations and impact of its Look East Policy. It evaluates India's changing role towards regional cooperation in South Asia and sub-regional groupings, the impact of domestic politics, and discusses how China has influenced Indian perceptions and strategy towards Asian regionalism. After a long gap, India is again contributing ideas on Asian integration and stresses that the broader East Asian integration process should remain open and inclusive.
Japanese Ideas of Asian Regionalism
Authors: INOGUCHI TAKASHI
Published: June 2011

Japan is geographically located on the fringe of Asia. Japan's location is often divided between those arguing that Japan is inside Asia and those arguing it is outside Asia. Japanese ideas of Asian regionalism are thus immensely varied. This article details a number of Japanese ideas on Asian regionalism with author/agency, scope and method specified. Special mention is made of weak integration of government agencies, thus causing proliferation of many Japanese ideas within Asia. With the increasing self-assertiveness of China, the apparent peaking out of American hegemony, and the steady rise of non-Chinese Asians, Japan tries to maintain enduring alliance with the United States, to invigorate interdependence with China, and to reinvent new relationships with the countries of the East Asian Summit. Japanese ideas of Asian regionalism take those templates as guidelines to develop new ideas of Asian regionalism.
Task and Relationship Conflict at Work
Authors: Lehmann-Willenbrock Nale , Grohmann Anna , Kauffeld Simone
Published: June 2011

The distinction between task and relationship conflict is well established. Based on Jehn’s (1995) intragroup conflict scale, we developed an economic six-item questionnaire for assessing relationship and task conflict in work groups. Confirmatory factor analysis was performed on data from a convenience sample (N = 247), and confirmed the original two-factor solution. The stability of the obtained two-factor solution was supported by confirmatory factor analysis in a longitudinal design with a second sample (N = 431) from the industrial sector. In line with previous research, the two types of conflict were intercorrelated. Moreover, the two subscales showed differential longitudinal effects on team outcomes. Task conflict was beneficial for performance in nonroutine tasks (but not in routine tasks). Relationship conflict had a negative impact on team viability and coworker trust.
Psychometric Properties of the Polish Version of the Interpersonal Competence Questionnaire (ICQ-R)
Authors: Górska Magdalena
Published: June 2011

This article presents the development and validation of the Polish version of the Interpersonal Competence Questionnaire – Revised (ICQ-R; Buhrmester, 2002 ; Buhrmester, Furman, Wittenberg & Reis, 1988 ). A total of 372 pupils and students (222 women and 150 men) aged 18–25 were studied. The instrument’s five-factor structure was confirmed and its reliability was satisfactory. Construct validity was investigated with respect to the NEO-FFI and to information on the participants’ relationship experiences and satisfaction with life. The majority of the ICQ-R scales correlated positively with Extraversion and Conscientiousness and negatively with Neuroticism. Participants who had never been in a romantic relationship were less interpersonally competent than participants who had such an experience. Competence was also related to the duration of the longest relationship and the number of relationships. Life satisfaction correlated positively with all the ICQ-R scales except Conflict Resolution.
Does Media Use Have a Short-Term Impact on Cognitive Performance?
Authors: Maass Asja , Klöpper Klara Maria , Michel Friederike , Lohaus Arnold
Published: June 2011

It has often been shown that the amount of media use is negatively related to cognitive outcomes. The more time spent on media the poorer cognitive performance is. This association has mainly been found for general-audience, violent, and action-loaded contents but not for educational contents. Typically, long-term-explanations like the time-displacement hypothesis are considered to account for this relation, although this cannot fully explain the association. Additionally short-term explanations should be considered, since it can be expected that media-induced stress can impair information processing. The present study compares short-term effects regarding memory performance and the ability to concentrate, using four different experimental conditions (high- vs. low-arousing films and video games). It was also examined if the experienced level of stress mediates group differences and if habitual media, habitual use of age-restricted contents or the trait sensation seeking moderate this mediation. Participants consisted of N = 117 university students. They were asked to learn written items before media use and to recall these after having used the media. Further, the ability to concentrate was measured. Experimental groups differed with regard to the cognitive outcome measures after media use. A significant univariate difference was found for high- vs. low-arousing contents in general (independent of type of media), the high-arousing content leading to poorer ability to concentrate after media use. The expected mediating and moderating effects are not supported. The study yields evidence that short-term mechanisms might play a role in explaining the negative correlations between media use and cognitive performance.
The Challenge of Constructing Psychologically Believable Agents
Authors: Schönbrodt Felix D. , Asendorpf Jens B.
Published: June 2011

Embodied conversational agents (ECAs) are designed to provide natural and intuitive communication with a human user. One major current topic in agent design consequently is to enhance their believability, often by incorporating internal models of emotions or motivations. As psychological theories often lack the necessary details for direct implementation, many agent modelers currently rely on models that are rather marginal in current psychological research, or models that are created ad hoc with little theoretical and empirical foundation. The goal of this article is both to raise psychologists’ awareness of the central challenges in the process of creating psychologically believable agents, and to recommend existing psychological frameworks to the virtual agents community that seem particularly useful for implementation in ECAs. Special attention is paid to a computationally detailed model of basic social motives that seems particularly useful for implementation: the Zurich model of social motivation.
Brachial artery flow-mediated dilation is not affected by pregnancy or regular exercise participation
Authors: Weissgerber Tracey L. , Davies Gregory A. L. , Tschakovsky Michael E.
Published: June 2011

Whether brachial artery FMD (flow-mediated dilation) is altered in pregnancy by 28–35 weeks compared with non-pregnant women remains controversial. The controversy may be due to limitations of previous studies that include failing to: (i) test non-pregnant controls in the mid-late luteal phase, (ii) account for effects of pregnancy on the dilatory shear stimulus, (iii) account for physical activity or (iv) control for inter-individual variation in the time to peak FMD. In the present study, brachial artery FMD was measured in 17 active and eight sedentary pregnant women (34.1±1.6 weeks of gestation), and in 19 active and 11 sedentary non-pregnant women (mid-late luteal phase). Decreased vascular tone secondary to increased shear stress contributes minimally to pregnancy-induced increases in baseline brachial artery diameter, as shear stress removal during distal cuff inflation in pregnant women did not reduce diameter to baseline levels observed in non-pregnant controls. Neither the shear stimulus nor the percentage FMD was affected by pregnancy or regular exercise. Continuous diameter measurements are required to control for delayed peak dilation during pregnancy (57±15 compared with 46±15 s; P=0.012), as post-release diameter measured at 60 or 55–65 s post-release underestimated FMD to a greater extent in non-pregnant than in pregnant women.
Chronic HgCl2 treatment increases vasoconstriction induced by electrical field stimulation: role of adrenergic and nitrergic innervation
Authors: Blanco-Rivero Javier , Furieri Lorena B. , Vassallo Dalton V. , Salaices Mercedes , Balfagón Gloria
Published: June 2011

In the present study, we have investigated the possible changes in rat mesenteric artery vascular innervation function caused by chronic exposure to low doses of HgCl2 (mercuric chloride), as well as the mechanisms involved. Rats were divided into two groups: (i) control, and (ii) HgCl2-treated rats (30 days; first dose, 4.6 μg/kg of body weight; subsequent dose, 0.07 μg·kg−1 of body weight·day−1, intramuscularly). Vasomotor response to EFS (electrical field stimulation), NA (noradrenaline) and the NO donor DEA-NO (diethylamine NONOate) were studied, nNOS (neuronal NO synthase) and phospho-nNOS protein expression were analysed, and NO, O2− (superoxide anion) and NA release were also determined. EFS-induced contraction was higher in the HgCl2-treated group. Phentolamine (1 μmol/l) decreased the response to EFS to a greater extent in HgCl2-treated rats. HgCl2 treatment increased vasoconstrictor response to exogenous NA and NA release. L-NAME (NG-nitro-L-arginine methyl ester; 0.1 mmol/l) increased the response to EFS in both experimental groups, but the increase was greater in segments from control animals. HgCl2 treatment decreased NO release and increased O2− production. Vasodilator response to DEA-NO was lower in HgCl2-treated animals. Tempol increased DEA-NO-induced relaxation to a greater extent in HgCl2-treated animals. nNOS expression was similar in arteries from both experimental groups, whereas phospho-nNOS was decreased in segments from HgCl2-treated animals. HgCl2 treatment increased vasoconstrictor response to EFS as a result of, in part, reduced NO bioavailability and increased adrenergic function. These findings offer further evidence that mercury, even at low concentrations, is an environmental risk factor for cardiovascular disease.
Oscillons: An encounter with dynamical chaos in 1953?
Authors: Denisov S. , Ponomarev A. V.
Published: June 2011

We discuss the works of one of electronic art pioneers, Ben F. Laposky (1914–2000), and argue that he might have been the first to create a family of essentially nonlinear analog circuits that allowed him to observe chaotic attractors.
Quenching dynamics in CdSe/ZnS core/shell quantum dots-gold nanoparticle conjugates in aqueous solution
Authors: Jin Li-Hua , Li Song-Mei , Kwon Bong-Joon , Cho Yong-Hoon
Published: June 2011

We investigated carrier dynamics of luminescence quenching in CdSe/ZnS core/shell quantum dots (QDs) in the absence and presence of gold nanoparticles (Au NPs) in aqueous solution. We emphasized that the observed quenching phenomenon in the QDs-Au NP composites can be a result of the interplay of the Förster resonance energy transfer and surface plasmon enhancement process of Au NPs on QDs. Different QDs with emission wavelengths varying from 545 to 619 nm were used to investigate the quenching dynamics. The recovery dynamics of the quenching was also confirmed by the addition of sodium chloride in the QDs-Au NP composites.
Convective transport by intermittent blob-filaments: Comparison of theory and experiment
Authors: D’Ippolito D. A. , Myra J. R. , Zweben S. J.
Published: June 2011

A blob-filament (or simply “blob”) is a magnetic-field-aligned plasma structure which is considerably denser than the surrounding background plasma and highly localized in the directions perpendicular to the equilibrium magnetic field B. In experiments and simulations, these intermittent filaments are often formed near the boundary between open and closed field lines, and seem to arise in theory from the saturation process for the dominant edge instabilities and turbulence. Blobs become charge-polarized under the action of an external force which causes unequal drifts on ions and electrons; the resulting polarization-induced E × B drift moves the blobs radially outwards across the scrape-off-layer (SOL). Since confined plasmas generally are subject to radial or outwards expansion forces (e.g., curvature and ∇B forces in toroidal plasmas), blob transport is a general phenomenon occurring in nearly all plasmas. This paper reviews the relationship between the experimental and theoretical results on blob formation, dynamics and transport and assesses the degree to which blob theory and simulations can be compared and validated against experiments.
Terahertz generation using a resonant-tunneling-like configuration in graphene
Authors: Dragoman D. , Dragoman M. , Hartnagel H.
Published: June 2011

The manuscript presents a simple graphene-based device able to generate at room temperature ultrashort pulses in the sub-picosecond range and thus able to generate signals up to 3–4 THz and beyond. The electrons produced by a short laser pulse incident on a graphene monolayer excite two oblique gates polarized with different dc voltages. The two gates are biased such that the quantum transmission has an isolated sharp peak in a narrow energy bandwidth. Such a transmission mimics the main property of a resonant tunneling structure, usually consisting of a semiconductor heterostructure, and generates an electric pulse with sub-picosecond duration and a spectrum with a cutoff frequency that can exceed 3 THz.
The problem of deficiency indices for discrete Schrödinger operators on locally finite graphs
Authors: Golénia Sylvain , Schumacher Christoph
Published: June 2011

The number of self-adjoint extensions of a symmetric operator acting on a complex Hilbert space is characterized by its deficiency indices. Given a locally finite unoriented simple tree, we prove that the deficiency indices of any discrete Schrödinger operator are either null or infinite. We also prove that all deterministic discrete Schrödinger operators which act on a random tree are almost surely self-adjoint. Furthermore, we provide several criteria of essential self-adjointness. We also address some importance to the case of the adjacency matrix and conjecture that, given a locally finite unoriented simple graph, its deficiency indices are either null or infinite. Besides that, we consider some generalizations of trees and weighted graphs.
Atomic layer deposition of Pb(Zr,Ti)Ox on 4H-SiC for metal-ferroelectric-insulator-semiconductor diodes
Authors: Zhang Feng , Perng Ya-Chuan , Choi Ju H. , Wu Tao , Chung Tien-Kan , Carman Gregory P. , Locke Christopher , Thomas Sylvia , Saddow Stephen E. , Chang Jane P.
Published: June 2011

Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 insulation layer on 4H-SiC substrate for metal-ferroelectric-insulator-semiconductor (MFIS) device applications. The as-deposited PZT was amorphous but crystallized into a perovskite polycrystalline structure with a preferred [002] orientation upon rapid thermal annealing (RTA) at 950 °C. The capacitance-voltage and current-voltage characteristics of the MFIS devices indicate carrier injection to the film induced by polarization and Fowler-Nordheim (FN) tunneling when electric field was high. The polarization-voltage measurements exhibited reasonable remanent and saturation polarization and a coercive electrical field comparable to that reported for bulk PZT. The piezoresponse force microscope measurements confirmed the polarization, coercive, and retention properties of ultra-thin ALD PZT films.
Large electric-induced pyroelectric properties in (Pb0.87La0.02Ba0.1) (Zr0.7Sn0.24Ti0.06)O3 antiferroelectric ceramics with excess PbO
Authors: Zhang Qingfeng , Jiang Shenglin , Zeng Yike , Fan Maoyan , Zhang Guangzu , Zhang Yangyang , Yu Yan , Wang Jing , He Jungang
Published: June 2011

(Pb0.87La0.02Ba0.1) (Zr0.7Sn0.24Ti0.06)O3 (PLBZST) antiferroelectric ceramics with the addition of 0–9 wt. % excess PbO were fabricated by the conventional solid-state reaction process, and their microstructure, dielectric, and pyroelectric properties were systemically investigated. When excess PbO content was less than 9 wt. %, two pyrochlore phases were formed along with the perovskite phase. Compared with common specimens, PLBZST antiferroelectric ceramics with excess PbO exhibited a higher pyroelectric coefficient and a lower dielectric loss, which are beneficial for the development of pyroelectric devices. Around the Curie temperature, as the excess PbO increased from 0 wt. % to 9 wt. %, PLBZST ceramics’ pyroelectric coefficient increased from 1600 μC/m2K to 4000 μC/m2K, and the figure of merit increased from 40 × 10−5 Pa−0.5 to 140 × 10−5 Pa−0.5 under a 400 V/mm dc field. The largest figure of merit of 200 × 10−5 Pa−0.5, which is about 8 times higher than that of conventional phase transition materials barium strontium titanate (BST), was obtained in PLBZST ceramics with 6 wt. % excess PbO when a 600 V/mm dc bias field was applied. Therefore, improvement of pyroelectric property is beneficial for the development of infrared detectors.
Largely enhanced energy density in epitaxial SmCo5/Fe/SmCo5 exchange spring trilayers
Authors: Sawatzki S. , Heller R. , Mickel Ch. , Seifert M. , Schultz L. , Neu V.
Published: June 2011

In order to enhance the energy density (BH)max as a key property for permanent magnet applications, exchanged-coupled trilayers of SmCo5/Fe/SmCo5 with fixed SmCo5 layer thicknesses (25 nm) and varying soft magnetic Fe film thickness have been epitaxially grown by pulsed laser deposition on Cr buffered MgO(110) substrates. The effect of the increasing soft layer thickness on the reversal mechanism and improved remanence due to the higher Fe-volume fraction was investigated by vibrating sample magnetometry in external fields up to 9 T. As the energy density strongly depends on the volume of the samples, emphasis is put on multilayer architecture investigation and reliable thickness determination. Concerning the latter all applied analysis methods as energy dispersive x-ray analysis, Rutherford backscattering spectroscopy and transmission electron microscopy confirm energy densities with maximum values of 312 kJ/m3 (39 MGOe) for a soft layer thickness of 12.6 nm.
SIESTA: A scalable iterative equilibrium solver for toroidal applications
Authors: Hirshman S. P. , Sanchez R. , Cook C. R.
Published: June 2011

A new solver for rapidly obtaining magnetohydrodynamic (MHD) equilibria in toroidal systems in the presence of islands and stochastic regions is described. It is based on the Kulsrud-Kruskal MHD energy minimization principle. To carry out this minimization, small displacements are made around a convenient set of curvilinear coordinates obtained from a nearby three-dimensional equilibrium that assumes nested surfaces. Because the changes of the magnetic fields and pressure are small, corresponding to small changes in the initial magnetic and kinetic energies, solutions for the linearized perturbations can be used to rapidly and iteratively find lower energy states with magnetic islands. A physics-based preconditioner is developed to accelerate the convergence of the iterative procedure to obtain an ideal MHD equilibrium with broken magnetic surfaces (islands).
Synthesis, electrical transport and optical properties of polyaniline-zirconium nanocomposite
Authors: Gupta K. , Jana P. C. , Meikap A. K.
Published: June 2011

Here, we report the synthesis of polyaniline-zirconium nanocomposite by chemical oxidative polymerization of aniline. Structural, thermal, and morphological properties of the samples are characterized by XRD, FTIR, TGA, SEM, and UV-Vis spectroscopy. Crystalline behavior of the nanocomposite has been obtained due to the presence of zirconium nanoparticles in polyaniline. FTIR analysis reveals the formation of polyaniline and changes to the structure of polyaniline due to the presence of zirconium nanoparticles. Granular morphology of the nanocomposite has been obtained from SEM micrographs and its conductivity has been increased due to the incorporation of zirconium nanoparticles. Temperature dependence of the resistivity has been fitted with ln [ρ(T)] ∝ T−1/4 which indicates three dimensional variable range hopping transport mechanism. ac conductivity follows the correlated barrier hopping transport mechanism. Some optical parameters like bandgap (Eg), peak transition energy (E0), and peak broadening parameter (C) are evaluated from real and imaginary dielectric functions. The value of the bandgap indicates the formation of a polaron lattice structure of the protonated emeraldine form of polyaniline.
Electron-impact excitation cross sections into Ne(2p53p) levels for plasma applications
Authors: Jung R. O. , Piech Garrett A. , Keeler M. L. , Boffard John B. , Anderson L. W. , Lin Chun C.
Published: June 2011

One requirement for plasma spectroscopy analysis and modeling of neon discharges is a set of electron-impact excitation cross sections covering excitation from both the 2p6 ground state and from the four 2p53s levels. We present experimental measurements for excitation cross sections into four J = 1 levels of the 2p53p configuration from the J = 0 and J = 2 2p53s metastable levels. A complete set of cross sections into all ten levels of the 2p53p configuration (2px in Paschen’s notation) from the ground state, the two metastable levels and the two resonance levels of the 2p53s configuration (1sy in Paschen’s notation) are compiled in convenient form. The resonance cross sections are obtained from an empirical scaling relationship between the measured metastable excitation cross sections and the corresponding optical oscillator strengths.
Effect of layer separation, InAs thickness, and rapid thermal annealing on the optical emission from a multi-layer quantum wire structure
Authors: Cui K. , Robinson B. J. , Thompson D. A. , Botton G. A.
Published: June 2011

Multi-layer InAs quantum wire stacks with different layer separations (8, 15, and 25 nm) and InAs thicknesses (3, 4, 5, and 7 monolayers [ML]) were grown on and embedded in In0.53Ga0.27Al0.20As barrier/spacer layers lattice-matched to an InP substrate. For the samples with 4 ML of InAs and different layer separations, double peak photoluminescence was observed from quantum wire stacks separated by 8 nm, and with a 15 nm spacer layer a long wavelength component was observed extending from the main peak. Only a single peak was found as the spacer layer thickness was increased to 25 nm. For the quantum wire stacks with different InAs layer thicknesses and a separation of 8 nm, double peak photoluminescence spectra were observed in the sample with 4 ML of InAs, and a main peak with a long wavelength component was obtained from the sample with 3 ML of InAs. Only a single peak was detectable for the InAs layer thicknesses of 5 and 7 ML. The optical emission features were studied via temperature and excitation laser power dependent photoluminescence. Based on the photoluminescence and transmission electron microscopy observations, photoluminescence spectral features can be attributed to a bi-modal height distribution in certain samples. In order to extend the optical emission to room temperature, the sample with 5 ML of InAs and an 8 nm spacer layer was subjected to post-growth rapid thermal annealing at different temperatures. The emission wavelength was tunable from 1.63 to 1.72 μm at room temperature.
Quantum nanojunctions as spintronic logic operators: Gate response in a two input ballistic interferometer
Authors: Bellucci S. , Onorato P.
Published: June 2011

We discuss the electron transport for a spin polarized current through a ballistic quantum nanojunction formed by two quantum dots (QDs) and a semiconducting quantum wire. We explore the possibilities of designing spintronic logic gates at the nano-scale level derivedfrom this device. Just one electron with a given spin polarization fills each QD and the stationary binary digit consists of the spin-up and spin-down of a single electron. Thus the spin polarizations of those electrons are treated as the two inputs of the gates. The AND, XOR, XNOR, and NOR gate response in the system is investigated beginning with the calculation of the low bias conductance-energy characteristic in the ballistic regime. Our study suggests that, for an appropriate choice of the working Fermi energy and of the distance between the QDs, a high output current (in the logical sense) appears for certain combinations of the inputs while it vanishes for others. It clearly demonstrates the logic gate behavior and this aspect may be utilized in designing a spintronic logic operator.
Contrast between the vertical and horizontal mercury discharge lamps
Authors: Ben Hamida M. B. , Helali H. , Araoud Z. , Charrada K.
Published: June 2011

This paper discusses the thermal behavior of a high pressure mercury lamp in a horizontal position, compared with that of a vertical lamp. The model adopted is three-dimensional, steady, and powered DC. After the model validation, we analyzed temperature fields and velocities for the case of the lamp in a horizontal position by comparing it with those of a lamp in vertical position. This setting initially fixed the wall temperature equal to 1000 K. However, the morphology of the temperature profile in the case of the horizontal lamp indicates that the temperature of the wall cannot be uniform. Thus, we have, in a second time, performed an energy balance at the wall to calculate its temperature. This aims to understand the influence of convection on the thermal properties of the source.
Stratified turbulence at the buoyancy scale
Authors: Waite Michael L.
Published: June 2011

Numerical simulations of forced stratified turbulence are presented, and the dependence on horizontal resolution and grid aspect ratio is investigated. Simulations are designed to model the small-scale end of the atmospheric mesoscale and oceanic submesoscale, for which high horizontal resolution is usually not feasible in large-scale geophysical fluid simulations. Coarse horizontal resolution, which necessitates the use of thin grid aspect ratio, yields a downscale stratified turbulence energy cascade in agreement with previous results. We show that with increasing horizontal resolution, a transition emerges at the buoyancy scale 2πU/N, where U is the rms velocity and N is the Brunt–Väisälä frequency. Simulations with high horizontal resolution and isotropic grid spacing exhibit a spectral break at this scale, below which there is a net injection of kinetic energy by nonlinear interactions with the large-scale flow. We argue that these results are consistent with a direct transfer of energy to the buoyancy scale by Kelvin–Helmholtz instability of the large-scale vortices. These findings suggest the existence of a distinct subrange of stratified turbulence between the buoyancy and Ozmidov scales. This range must be at least partially resolved or parameterized to obtain robust simulations of larger-scale turbulence.
A mathematical framework for forcing turbulence applied to horizontally homogeneous stratified flow
Authors: Rao K. J. , de Bruyn Kops S. M.
Published: June 2011

It is often desirable to study turbulent flows at steady state even if the flow has no inherent source of turbulence kinetic energy. Doing so requires a forcing schema, and various methods applicable to laboratory experiments or numerical simulations have been studied extensively for turbulence that is isotropic and homogeneous in three dimensions. A review of existing schemata for simulations is used to form a framework for more general forcing methods. In this framework, the problem of developing a forcing method is abstracted into the two problems of (1) prescribing the spectrum of the input power and (2) specifying a force that has the desired characteristics and that adds energy to the flow with the correct spectrum. The framework is used to construct three forcing methods for simulating horizontally homogeneous and isotropic, vertically stratified turbulence. They are implemented in a pseudo-spectral large-eddy simulations and their characteristics are analyzed. The framework is then used to characterize existing laboratory experiments. While no exact analogy can be drawn between forcing in esoteric pseudo-spectral simulations and forcing in physical experiments, there are many similarities. It is suggested that the forcing framework can be applied to predict and systematically test the effects of configuration choices made in the design of simulations and laboratory experiments.
The investigation of point defect modes of phononic crystal for high Q resonance
Authors: Li Feng , Liu Jun , Wu Yihui
Published: June 2011

Point defect cavity was constructed in a two-dimensional phononic crystal plate. It was excited by a small piezo chip in the cavity, and the vibrations of each point defect mode were detected by an optical interferometer. Point defect modes on 2D phononic crystal plate in vacuum, air, and with water loaded were investigated theoretically and experimentally. It is shown that the Q factors of the point defect modes are determined by inner attenuation, bandgap effects, and medium. The SSS mode (breathing mode) has highest Q factor in vacuum and air among nine modes thanks to low inner attenuation and low energy leakage. By selectively loading the PC with water on one side, the point defect modes with shear movement surfaces suffer lower attenuation and still have rather high Q factors. These conclusions will help to design a new kind of resonator or sensor.
Ab initio molecular dynamics simulation of binary Cu64Zr36 bulk metallic glass: Validation of the cluster-plus-glue-atom model
Authors: Tian Hua , Zhang Chong , Wang Lu , Zhao JiJun , Dong Chuang , Wen Bin , Wang Qing
Published: June 2011

We have performed ab initio molecular dynamics simulation of Cu64Zr36 alloy at descending temperatures (from 2000 K to 400 K) and discussed the evolution of short-range order with temperature. The pair-correlation functions, coordination numbers, and chemical compositions of the most abundant local clusters have been analyzed. We found that icosahedral short-range order exists in the liquid, undercooled, and glass states, and it becomes dominant in the glass states. Moreover, we demonstrated the existence of Cu-centered Cu8Zr5 icosahedral clusters as the major local structural unit in the Cu64Zr36 amorphous alloy. This finding agrees well with our previous cluster model of Cu-Zr-based BMG as well as experimental evidences from synchrotron x ray and neutron diffraction measurements.
Selective fibronectin adsorption against albumin and enhanced stem cell attachment on helium atmospheric pressure glow discharge treated titanium
Authors: Han Inho , Vagaska Barbora , Joo Park Bong , Lee Mi Hee , Jin Lee Seung , Park Jong-Chul
Published: June 2011

Successful tissue integration of implanted medical devices depends on appropriate initial cellular response. In this study, the effect of helium atmospheric pressure glow discharge (He-APGD) treatment of titanium on selective protein adsorption and the initial attachment processes and focal adhesion formation of osteoprogenitor cells and stem cells were examined. Titanium disks were treated in a self-designed He-APGD system. Initial attachment of MC3T3-E1 mouse pre-osteoblasts and human mesenchymal stem cells (MSCs) was evaluated by MTT assay and plasma membrane staining followed by morphometric analysis. Fibronectin adsorption was investigated by Enzyme-Linked ImmunoSorbant Assay. MSCs cell attachment to treated and non-treated titanium disks coated with different proteins was verified also in serum-free culture. Organization of actin cytoskeleton and focal adhesions was evaluated microscopically. He-APGD treatment effectively modified the titanium surfaces by creating a super-hydrophilic surface, which promoted selectively higher adsorption of fibronectin, a protein of critical importance for cell/biomaterial interaction. In two different types of cells, the He-APGD treatment enhanced the number of attaching cells as well as their attachment area. Moreover, cells had higher organization of actin cytoskeleton and focal adhesions. Faster acceptance of the material by the progenitor cells in the early phases of tissue integration after the implantation may significantly reduce the overall healing time; therefore, titanium treatment with He-APGD seems to be an effective method of surface modification of titanium for improving its tissue inductive properties.
Analyticity and uniform stability in the inverse spectral problem for Dirac operators
Authors: Hryniv Rostyslav O.
Published: June 2011

We prove that the inverse spectral mapping reconstructing the square integrable potentials of Dirac operators on [0, 1] in the AKNS form from their spectral data (two spectra or one spectrum and the corresponding norming constants) is analytic and uniformly stable in a certain sense.
Shortening x-ray pulses for pump-probe experiments at synchrotrons
Authors: Navirian H. A. , Herzog M. , Goldshteyn J. , Leitenberger W. , Vrejoiu I. , Khakhulin D. , Wulff M. , Shayduk R. , Gaal P. , Bargheer M.
Published: June 2011

We implemented an experimental scheme for ultrafast x-ray diffraction at storage rings based on a laser-driven Bragg-switch that shortens the x-ray pulses emitted from an undulator. The increased time-resolution is demonstrated by observing changes of intensity, position and width of the diffraction peaks of a La0.7Sr0.3MnO3/SrTiO3 superlattice sample after optical excitation, i.e., by quantitatively measuring the propagation of an expansion wave through the sample. These experimental transients with timescales of 35 to 60 ps evidence a reduction of the x-ray pulse duration by a factor of two.
Binary jumps in continuum. I. Equilibrium processes and their scaling limits
Authors: Finkelshtein Dmitri L. , Kondratiev Yuri G. , Kutoviy Oleksandr V. , Lytvynov Eugene
Published: June 2011

Let Γ denote the space of all locally finite subsets (configurations) in \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^d$\end{document}Rd. A stochastic dynamics of binary jumps in continuum is a Markov process on Γ in which pairs of particles simultaneously hop over \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^d$\end{document}Rd. In this paper, we study an equilibrium dynamics of binary jumps for which a Poisson measure is a symmetrizing (and hence invariant) measure. The existence and uniqueness of the corresponding stochastic dynamics are shown. We next prove the main result of this paper: a big class of dynamics of binary jumps converge, in a diffusive scaling limit, to a dynamics of interacting Brownian particles. We also study another scaling limit, which leads us to a spatial birth-and-death process in continuum. A remarkable property of the limiting dynamics is that its generator possesses a spectral gap, a property which is hopeless to expect from the initial dynamics of binary jumps.