bluuebunny/crossref_metadata_2025 huggingface dataset:
Alternating Current Electro-Osmotic Flow of the Maxwell Fluids Through a Circular Micro-Pipe
Authors: Sun L.-X. , Jian Y.-J. , Chang L. , Zhang H.-Y. , Liu Q.-S.
Published: December 2012

Analytical solutions are presented for time periodic EOF flow of linear viscoelastic fluids through a cylindrical micro-pipe. The linear viscoelastic fluids used here are described by the general Maxwell model. The solution involves analytically solving the linearized Poisson-Boltzmann equation, together with the Cauchy momentum equation and the general Maxwell constitutive equation considering the depletion effect produced by the interaction between macro-molecules of the Maxwell fluid and the channel surface. The overall flow is divided into depletion layer and bulk flow outside of depletion layer. The velocity expressions of these two layers were obtained, respectively. By numerical computations, the influences of the periodic EOF electric oscillating Reynolds number Re, Deborah number De, depletion layer thickness δ and the viscosity ratio γ of Maxwell to Newtonian fluids on velocity profile are presented. For a prescribed De, the increasing Re will cause large changes of the EOF velocity with decreasing velocity magnitude. For a given Re, large De gives large EOF velocity magnitude. Increasing γ will lead to larger velocity amplitude for a given lower Re. However, at higher Re, the velocity amplitude decreases with the viscosity ratio γ, especially within the depletion layer. In addition, large depletion layer thickness gives small EOF velocity magnitude for fixed Re and De. Finally, the influence of De on energy dissipation is studied. These results provide a detail insight of the flow characteristic of this flow configuration.
Error Estimation for Neglecting Unsteady Hydrodynamic Forces in the Equation of Motion for an Immersed Pendulum
Authors: Yang F.-L.
Published: December 2012

The unsteady motion of a fully immersed solid sphere at low to moderate particle Reynolds number, from 1 to about 1600, has been modeled by considering the quasi-steady viscous drag, the added mass force, and the history force. The last force results from unsteady boundary layer growth and is often neglected in multiphase flow applications due to its complex formula. However, it has been shown that this unsteady viscous force is more crucial than the widely employed added mass force to describe an unsteady sphere motion. Thus, targeting the flow regime when the quasi-steady viscous drag is dominating, this work proposes two simple formulae to approximate the errors of neglecting either the history force or the added mass force in describing a fully immersed spherical pendulum motion. The proposed formulae are shown to capture the actual error when the numerical solution of a partial model that omits one force component is compared to the full model prediction when the sphere density is not too close to the ambient liquid.
The significance of the boundary between the Rhoscolyn and New Harbour formations on Holy Island, North Wales, to the deformation history of Anglesey
Authors: TREAGUS JACK E. , TREAGUS SUSAN H. , WOODCOCK NIGEL H.
Published: December 2012

The boundary between the Rhoscolyn and New Harbour formations on Holy Island, Anglesey, has been described as a high strain zone or as a thrust. The boundary is here described at four localities, with reference to the contrasting sedimentary and deformational character of the two formations. At one of these localities, Borth Wen, sandstones and conglomerates at the top of the Rhoscolyn Formation are followed, without any break, by tuffs and then mudstones of the New Harbour Formation. It is concluded that there is clear evidence of depositional continuity across the boundary here, and that both formations subsequently shared a common two-phase deformation. The first (D1) was manifestly different in intensity and scale in the two formations, whereas the second (D2) produced very similar structures in both. The other three localities provide continuity of sedimentary and tectonic features at this boundary in a traverse along the length of Holy Island, leading us to identify two previously unrecognized major D1 folds in addition to the Rhoscolyn Anticline. At one of these localities (Holyhead), we confirm the presence of Skolithos just below the boundary, supporting radiometric evidence for a lower Cambrian or later age for the Rhoscolyn Formation. A turbidite interpretation for both the Rhoscolyn and New Harbour formations best fits the available evidence. A deep-water depositional environment is still compatible with the sporadic presence of Skolithos burrows, but less so with reported observations of hummocky and swaley cross-stratification lower down the South Stack Group.
Proteolysis, lipolysis, volatile compounds and sensory characteristics of Hispánico cheeses made using frozen curd from raw and pasteurized ewe milk
Authors: Alonso Rocío , Picon Antonia , Gaya Pilar , Nuñez Manuel
Published: December 2012

Hispánico cheese, manufactured from a mixture of cow and ewe milk, is representative of cheese varieties made using milk from more than one animal species in Mediterranean countries. The shortage of ewe milk production in autumn hinders the uniformity of Hispánico cheese composition throughout the year. To surmount this inconvenience of ewe milk seasonality, curds made in spring from raw and pasteurized ewe milk were stored frozen and used four months later for the manufacture of Hispánico cheese. Experimental cheeses were made by mixing fresh curd from pasteurized cow milk with thawed curd from raw or pasteurized ewe milk, and control cheese from a mixture of pasteurized cow and ewe milk in the same proportion. Characteristics of experimental and control cheeses throughout a 60-d ripening period were investigated. On the one hand, the experimental cheese containing frozen curd from raw ewe milk showed the highest counts of staphylococci, Gram-negative bacteria and coliforms, the highest levels of aminopeptidase and esterase activity, and the highest concentrations of free amino acids, free fatty acids, alcohols and esters. On the other, the experimental cheese containing frozen curd from pasteurized ewe milk had concentrations of free amino acids, free fatty acids and volatile compounds similar to those of control cheese, with the only exception being a higher level of ketones. Flavour intensity reached the highest scores in the experimental cheese containing frozen curd from raw ewe milk, followed by the experimental cheese containing frozen curd from pasteurized ewe milk. Flavour quality scores of both experimental cheeses were similar, and lower than those of control cheese.
Relationship between hearing loss and sexual dysfunction
Authors: Bakır S , Penbegül N , Gün R , Yorgancilar E , Kiniş V , Özbay M , Atar M , Güneş M
Published: December 2012

Objective:

Deafness may be one of the factors that leads to a change in sexual function. This study aimed to assess sexual function, in particular erectile dysfunction, in male patients with hearing loss.

Materials and methods:

We studied two groups: (1) adult men with acquired, bilateral, sensorineural hearing loss, and (2) healthy, adult, married men demonstrated to have normal hearing levels, as the control group. Sexual function was assessed using the International Index of Erectile Functions questionnaire, and quality of life using the 36-Item Short-Form Health Survey.

Results:

There was a statistically significant difference between the groups regarding the International Index of Erectile Functions questionnaire results (p <0.001), both for each of the five questionnaire domain scores and for the total score.

Conclusion:

Our results indicate that men with mild or moderate sensorineural hearing loss have poorer sexual health.
Human hepatic stellate cells in primary culture are safe targets forLeishmania donovani
Authors: ROSTAN O. , ROBERT-GANGNEUX F. , LAMBERT M. , SAMSON M. , GANGNEUX J. P.
Published: December 2012

Leishmaniaparasites can escape the immune response by invading cell types lacking leishmanicidal mechanisms. Silent persistence ofLeishmaniaparasites in the host organism is responsible for asymptomatic carriage and relapses after cured leishmaniasis. Here, we studied the interaction between Hepatic Stellate Cells (HSC) andLeishmania.An original model of human HSC in primary culture infected withL. donovaniwas developed. The presence of intracellular parasites was studied and quantified using optical and confocal microscopy. HSC characteristics were studied using microscopy, methylene blue assay, long-term cultures and qPCR. We showed for the first time that human HSC are permissive toL. donovaniinfection, with no modification of HSC survival, growth rate and proinflammatory and fibrogenic characteristics. Intracellular parasites did not replicate but HSC had no effect on their survival. Indeed, after a 40-day culture, infected HSC cultures transferred on NNN medium yielded new promastigotes that were able to proliferate and efficiently infect new cells. HSC are permissive toL. donovani, with neither parasite killing nor apparent cell damage. Thus, HSC could act as potent sanctuary cells forLeishmaniain the liver, which could partially explain parasite reactivation after an asymptomatic carriage or a cured visceral leishmaniasis.
Human reasoning includes a mental logic
Authors: O'Brien David P.
Published: December 2012

Oaksford & Chater (O&C) have rejected logic in favor of probability theory for reasons that are irrelevant to mental-logic theory, because mental-logic theory differs from standard logic in significant ways. Similar to O&C, mental-logic theory rejects the use of the material conditional and deals with the completeness problem by limiting the scope of its procedures to local sets of propositions.
Financial planning for social care in later life: the ‘shadow’ of fourth age dependency
Authors: PRICE DEBORA , BISDEE DINAH , DALY TOM , LIVSEY LYNNE , HIGGS PAUL
Published: December 2012

As policy makers in the United Kingdom and many other countries grapple with financing the needs of an ageing population, financial planning for social care in later life is high on political agendas. We draw on qualitative research with older couples in the United Kingdom about their intimate money practices to analyse the day-to-day meanings attributed to money, saving and consumption in the context of financial planning for later life and death. We find that expenditure on funerals and home adaptations is discussed, negotiated and planned, as is ‘downsizing’ to release capital from the home for financing day-to-day expenses and leisure expenses. These outcomes are within easy contemplation and indeed money practice of older couples. In contrast, end-of-life planning for domiciliary or residential care was virtually non-existent across all socio-economic groups, and couples employed a range of techniques to avoid making these discussions ‘real’. Costs (while well known) are seen as astronomical, details are scarce, intensive domiciliary care is never discussed, and death is seen as preferable to residential care. We theorise antipathy to care planning as a product of social and psychological construction of the ‘fourth age’ as a period of abjection, and therefore ‘wasted’ expenditure. Exhortations by policy makers for individuals to consider care costs will be ineffective without recognition of the cultural transformation of later life.
SUPPORTING DECISION MAKING IN CROSS-BORDER REGIONS: A HEALTH TECHNOLOGY ASSESSMENT TOOL FOR HOSPITALS
Authors: Knies Saskia , Lombardi Gloria , Commers Matt , Dauben Hans-Peter , Evers Silvia , Michelsen Kai , Oortwijn Wija , Opara Chibuzo , Brand Helmut
Published: December 2012

Objectives: The aim of this study was to develop an health technology assessment (HTA) decision tool to support the decision-making process on health technologies for hospital decision makers in cross-border regions.

Methods: Several methods were used to collect information necessary to develop the cross-border mini-HTA decision tool. The literature was inventoried on HTA in border regions and local settings and the use of HTA by local decision makers. Semi-structured interviews with hospital decision makers in cross-border regions were also performed. Based on group discussion of the resulting information, it was decided to use the Danish mini-HTA guideline as a starting point for development of the decision tool. After finishing the first version of the decision tool it was tested in two pilot studies

Results: Some questions in the Danish mini-HTA guideline were not relevant. Other questions needed rephrasing and questions about cross-border situations were added. The pilots showed several missing topics, including legal questions and reimbursement issues. The final decision tool consists of three sections: a general section, a section for hospitals not cooperating cross-border and a section for hospitals that are cooperating with hospitals across a national or regional border.

Conclusions: Based on our literature search, this may be the first cross-border mini-HTA decision tool. The decision tool will be of help for healthcare professionals and decision makers in border settings who would like to use HTA evidence to support their decision-making process.
CONDITIONAL SOJOURN TIMES OF PROCESSOR-SHARING QUEUES
Authors: Lee Wei-Yi , Wang Chia-Li
Published: December 2012

Queues operated by a processor-sharing mode have important applications in many modern systems. However, because of the simultaneous sharing of service capacity by all customers, the distribution function and moments of the sojourn time are difficult to derive, even with a given initial condition. In addition, when a limit on the number of customers in the system is enforced to ensure the quality of service, the sojourn time becomes more complicated. In recent literature, the distribution function is obtained via the Laplace–Stieltjes transform. In this paper, we take a pure algebraic approach to derive the moments of the sojourn time. We obtain an iterative formula and use it to investigate properties of the conditional sojourn time. The approach is simple and intuitive, and applies to queues with multiple class customers as well.
When do infants begin recognizing familiar words in sentences?
Authors: DEPAOLIS RORY A. , VIHMAN MARILYN M. , KEREN-PORTNOY TAMAR
Published: December 2012

Previous studies have shown that by 11 but not by 10 months infants recognize words that have become familiar from everyday life independently of the experimental setting. This study explored the ability of 10-, 11-, and 12-month-old infants to recognize familiar words in sentential context, without experimental training. The headturn preference procedure was used to contrast passages containing words likely to be familiar to the infants with passages containing words unlikely to have been previously heard. Two stimulus words were inserted near the beginning and end of each of a set of simple sentence frames. The ability to recognize the familiar words within sentences emerged only at 12 months of age. The contrast between segmentation abilities as they emerge as a result of everyday exposure to language, as assessed here, and those abilities as measured in studies in which words are experimentally trained is discussed in terms of memory-based mechanisms.
Planning and its discontents: contradictions and continuities in remaking China's great cities, 1950–2010
Authors: LIANG SAMUEL Y.
Published: December 2012

This article offers a theoretical overview of the urbanization legacy of China's great cities since 1949. It shows a persistent contradiction between ideology/planning and urban sprawl/cellular urbanism. The symbolic function of city planning reflects official ideology giving the city a unified formal structure, but the implementation of the city plan is compromised in the process of urban development. The state governance fragments Chinese urban society into emplaced groups. This social division takes effect through the spatial division of various compounds that negotiate with rather than conform to city planning. Using a case-study of Guangzhou's urban development, the article shows how the state-led spatial practices continue in the post-socialist era and how a new kind of developmental ideology informs urban developments.
Semi-detached Britain? Reviewing suburban engagement in twentieth-century society
Authors: BALDERSTONE LAURA
Published: December 2012

Over the last century, cultural and scholarly depictions of middle-class suburbia have created a stereotype that suggests detachment, indifference and the decline of community engagement. Yet, such accounts oversimplify the middle-class experience and the evolving nature of the urban/suburban relationship. Offering a review of existing literature, this article seeks to challenge existing stereotypes by revaluating the social networks constructed by middle-class ‘suburbans’. Far from detached and disengaged, the spatial analysis of associational membership in post-war Leicester reveals the need for a much wider revision of the British suburban narrative.
Prehospital Sepsis Project (PSP): Knowledge and Attitudes of United States Advanced Out-of-Hospital Care Providers
Authors: Báez Amado Alejandro , Hanudel Priscilla , Perez Maria Teresa , Giraldez Ediza M. , Wilcox Susan R.
Published: December 2012

Introduction

Severe sepsis and septic shock are common and often fatal medical problems. The Prehospital Sepsis Project is a multifaceted study that aims to improve the out-of-hospital care of patients with sepsis by means of education and enhancement of skills. The objective of this Project was to assess the knowledge and attitudes in the principles of diagnosis and management of sepsis in a cohort of United States out-of-hospital care providers.

Methods

This was cross-sectional study. A 15-item survey was administered via the Web and e-mailed to multiple emergency medical services list-servers. The evaluation consisted of four clinical scenarios as well as questions on the basics of sepsis. For intra-rater reliability, the first and the fourth scenarios were identical. Chi-square and Fisher's Exact testing were used to assess associations. Relative risk (RR) was used for strength of association. Statistical significance was set at .05.

Results

A total of 226 advanced EMS providers participated with a 85.4% (n = 193) completion rate, consisting of a 30.7% rural, 32.3% urban, and 37.0% suburban mix; 82.4% were paramedics and 72.5% had worked in EMS >10 years. Only 57 (29.5%) participants scored both of the duplicate scenarios correctly, and only 19 of the 193 (9.8%) responded to all scenarios correctly. Level of training was not a predictor of correctly scoring scenarios (P = .71, RR = 1.25, 95% CI = 0.39-4.01), nor was years of service (P = .11, RR = 1.64, 95% CI = 0.16-1.21).

Conclusions

Poor understanding of the principles of diagnosis and management of sepsis was observed in this cohort, suggesting the need for enhancement of education. Survey items will be used to develop a focused, interactive Web-based learning program. Limitations include potential for self-selection and data accuracy.

Báez AA, Hanudel P, Perez MT, Giraldez EM, Wilcox SR. Prehospital sepsis project (PSP): knowledge and attitudes of United States advanced out-of-hospital care providers. Prehosp Disaster Med. 2013;28(2):1-3.
Confocal Raman Microscopy. Thomas Dieing, Olaf Hollricher, and Jan Toporski (Eds.)
Authors: Schlücker Sebastian
Published: December 2012

Confocal Raman Microscopy. Thomas Dieing, Olaf Hollricher, and Jan Toporski (Eds.). Springer, New York, 2011, 289 pages. ISBN 978-3642125218

Raman microscopy is the combination of Raman spectroscopy with optical light microscopy and was first presented in the mid-1970s. It combines the advantages of vibrational Raman spectroscopy as a noninvasive technique providing a wealth of chemical information on the properties of molecules and solids with the imaging capabilities and small sample volume requirements of an optical microscope. “Seeing is believing”: Raman microscopy can visualize the inherent chemical inhomogeneity of a sample without the need of external labels, information that cannot be obtained from simply looking at an unstained sample in the standard optical microscope. During the last decade, confocal Raman microscopy has gone through a rapid development with respect to instrumentation and software as well as the diversity of applications.
Age-modulated association between prefrontal NAA and the BDNF gene
Authors: Salehi Basira , Preuss Nora , van der Veen Jan Willem , Shen Jun , Neumeister Alexander , Drevets Wayne C. , Hodgkinson Colin , Goldman David , Wendland Jens R. , Singleton Andrew , Gibbs Jesse R. , Cookson Mark R. , Hasler Gregor
Published: December 2012

Brain-derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of psychiatric and neurological disorders and in the mechanisms of antidepressant pharmacotherapy. Psychiatric and neurological conditions have also been associated with reduced brain levels of N-acetyl-aspartate (NAA), which has been used as a putative marker of neural integrity. However, few studies have explored the relationship between BDNF polymorphisms and NAA levels directly. Here, we present data from a single-voxel proton magnetic resonance spectroscopy study of 64 individuals and explore the relationship between BDNF polymorphisms and prefrontal NAA level. Our results indicate an association between a single nucleotide polymorphism (SNP) within BDNF, known as rs1519480, and reduced NAA level (p = 0.023). NAA levels were further predicted by age and Asian ancestry. There was a significant rs1519480 × age interaction on NAA level (p = 0.031). Specifically, the effect of rs1519480 on NAA level became significant at age ⩾34.17 yr. NAA level decreased with advancing age for genotype TT (p = 0.001) but not for genotype CT (p = 0.82) or CC (p = 0.34). Additional in silico analysis of 142 post-mortem brain samples revealed an association between the same SNP and reduced BDNF mRNA expression in the prefrontal cortex. The rs1519480 SNP influences BDNF mRNA expression and has an impact on prefrontal NAA level over time. This genetic mechanism may contribute to inter-individual variation in cognitive performance seen during normal ageing, as well as contributing to the risk for developing psychiatric and neurological conditions.
Children and Financial Education: Challenges for Developing Financial Capability in the Classroom
Authors: Appleyard Lindsey , Rowlingson Karen
Published: December 2012

Financial education is viewed by both policy makers and the public as an increasingly important tool for developing financially capable citizens in an era of increasing individual financial responsibility. This paper considers the recent history of school involvement in teaching financial education. It then draws on research undertaken in summer 2010 at two Birmingham primary schools to explore children's understandings of key financial issues. The paper concludes that there appears to be a groundswell of momentum behind making financial education a compulsory part of the National Curriculum, but, even if this happens, there will be challenges in delivering such education in practice. For example, the role of values in financial education makes it a contested subject and teachers will need training and support to deal with this. They will also need to be supported to deliver financial education in a way which recognises diversity and sensitivity issues in the classroom.
Islamist Rationality: An Assessment of the Rational Choice Approach
Authors: Çavdar Gamze
Published: December 2012

A growing body of literature criticizes the notion that Islamism issui generisand argues that it could be explained by existing conceptions about human behavior. This approach relies on rational choice theory and its derivatives, characterizing Islamists as rational political actors that engage in cost-benefit analysis and strategic calculation. This article evaluates the explanatory power of this characterization through three case studies, namely the Turkish Justice and Development Party (Adalet ve Kalkınma Partisi), the Jordanian Islamic Action Front (Jabhat al-Amal al-Islami), and the Egyptian Muslim Brotherhood (Ikhwan al-Muslimun). It argues that although the approach offers explanations for Islamist pragmatism, this characterization has three major limitations: lack of room for ideological change, extreme voluntarism between violence and non-violence, and lack of insight for intra-group gender relations.
Re-examinging the Wall of Separation: A Cross-National Study of Religious Pluralism and Democracy
Authors: Rebe Ryan J.
Published: December 2012

Mutual autonomy between religious and state institutions is often seen as a key ingredient for democratization. Yet, there are a large number of democracies with an established religion. If a separation of church and state is desirable for the maintenance of a stable democracy, then why do so many democracies continue to support religious institutions and practices? As the evidence from this study reveals, the difference between democracies and non-democracies does not depend on a wall of separation between church and state, but instead, on the protection of religious freedom for minority groups and the promotion of secular legislation.
Anaerobic degradation of propane and butane by sulfate-reducing bacteria enriched from marine hydrocarbon cold seeps
Authors: Jaekel Ulrike , Musat Niculina , Adam Birgit , Kuypers Marcel , Grundmann Olav , Musat Florin
Published: December 2012

The short-chain, non-methane hydrocarbons propane and butane can contribute significantly to the carbon and sulfur cycles in marine environments affected by oil or natural gas seepage. In the present study, we enriched and identified novel propane and butane-degrading sulfate reducers from marine oil and gas cold seeps in the Gulf of Mexico and Hydrate Ridge. The enrichment cultures obtained were able to degrade simultaneously propane and butane, but not other gaseous alkanes. They were cold-adapted, showing highest sulfate-reduction rates between 16 and 20 °C. Analysis of 16S rRNA gene libraries, followed by whole-cell hybridizations with sequence-specific oligonucleotide probes showed that each enrichment culture was dominated by a unique phylotype affiliated with the Desulfosarcina-Desulfococcus cluster within the Deltaproteobacteria. These phylotypes formed a distinct phylogenetic cluster of propane and butane degraders, including sequences from environments associated with hydrocarbon seeps. Incubations with 13C-labeled substrates, hybridizations with sequence-specific probes and nanoSIMS analyses showed that cells of the dominant phylotypes were the first to become enriched in 13C, demonstrating that they were directly involved in hydrocarbon degradation. Furthermore, using the nanoSIMS data, carbon assimilation rates were calculated for the dominant cells in each enrichment culture.
Signal transfer in the plant plasma membrane: phospholipase A2 is regulated via an inhibitory Gα protein and a cyclophilin
Authors: Heinze Michael , Herre Madeleine , Massalski Carolin , Hermann Isabella , Conrad Udo , Roos Werner
Published: December 2012

The plasma membrane of the California poppy is known to harbour a PLA2 (phospholipase A2) that is associated with the Gα protein which facilitates its activation by a yeast glycoprotein, thereby eliciting the biosynthesis of phytoalexins. To understand the functional architecture of the protein complex, we titrated purified plasma membranes with the Gα protein (native or recombinant) and found that critical amounts of this subunit keep PLA2 in a low-activity state from which it is released either by elicitor plus GTP or by raising the Gα concentration, which probably causes oligomerization of Gα, as supported by FRET (fluorescence resonance energy transfer)-orientated fluorescence imaging and a semiquantitative split-ubiquitin assay. All effects of Gα were blocked by specific antibodies. A low-Gα mutant showed elevated PLA2 activity and lacked the GTP-dependent stimulation by elicitor, but regained this capability after pre-incubation with Gα. The inhibition by Gα and the GTP-dependent stimulation of PLA2 were diminished by inhibitors of peptidylprolyl cis–trans isomerases. A cyclophilin was identified by sequence in the plasma membrane and in immunoprecipitates with anti-Gα antibodies. We conclude that soluble and target-associated Gα interact at the plasma membrane to build complexes of varying architecture and signal amplification. Protein-folding activity is probably required to convey conformational transitions from Gα to its target PLA2.
Power loss of an oscillating electric dipole in a quantum plasma
Authors: Ghaderipoor L. , Mehramiz A.
Published: December 2012

A system of linearized quantum plasma equations (quantum hydrodynamic model) has been used for investigating the dispersion equation for electrostatic waves in the plasma. Furthermore, dispersion relations and their modifications due to quantum effects are used for calculating the power loss of an oscillating electric dipole. Finally, the results are compared in quantum and classical regimes.
A computational approach to continuum damping of Alfvén waves in two and three-dimensional geometry
Authors: Könies Axel , Kleiber Ralf
Published: December 2012

While the usual way of calculating continuum damping of global Alfvén modes is the introduction of a small artificial resistivity, we present a computational approach to the problem based on a suitable path of integration in the complex plane. This approach is implemented by the Riccati shooting method and it is shown that it can be transferred to the Galerkin method used in three-dimensional ideal magneto-hydrodynamics (MHD) codes. The new approach turns out to be less expensive with respect to resolution and computation time than the usual one. We present an application to large aspect ratio tokamak and stellarator equilibria retaining a few Fourier harmonics only and calculate eigenfunctions and continuum damping rates. These may serve as an input for kinetic MHD hybrid models making it possible to bypass the problem of having singularities on the path of integration on one hand and considering continuum damping on the other.
Energy fluxes in a radio-frequency magnetron discharge for the deposition of superhard cubic boron nitride coatings
Authors: Bornholdt S. , Ye J. , Ulrich S. , Kersten H.
Published: December 2012

Energy flux measurements by a calorimetric probe in a rf-magnetron plasma used for the deposition of super-hard c-BN coatings are presented and discussed. Argon as working gas is used for sputtering a h-BN target. Adding a certain amount of N2 is essential for the formation of stoichiometric BN films, since a lack of nitrogen will lead to boron rich films. Subsequently, the contributions of different plasma species, surface reactions, and film growth to the resulting variation of the substrate temperature in dependence on nitrogen admixture are estimated and discussed. In addition, SRIM simulations are performed to estimate the energy influx by sputtered neutral atoms. The influence of magnetron target power and oxygen admixture (for comparison with nitrogen) to the process gas on the total energy flux is determined and discussed qualitatively, too. The results indicate that variation of the energy influx due to additional nitrogen flow, which causes a decrease of electron and ion densities, electron temperature and plasma potential, is negligible, while the admixture of oxygen leads to a drastic increase of the energy influx. The typical hysteresis effect which can be observed during magnetron sputtering in oxygen containing gas mixtures has also been confirmed in the energy influx measurements for the investigated system. However, the underlying mechanism is not understood yet, and will be addressed in further investigations.
Mathematical estimation of melt depth in conduction mode of laser spot remelting process
Authors: Hadi Iraj
Published: December 2012

A one-dimensional mathematical model based on the front tracking method was developed to predict the melt depth as a function of internal and external parameters of laser spot remelting process in conduction mode. Power density, pulse duration, and thermophysical properties of material including thermal diffusivity, melting point, latent heat, and absorption coefficient have been taken into account in the model of this article. By comparing the theoretical results and experimental welding data of commercial pure nickel and titanium plates, the validity of the developed model was examined. Comparison shows a reasonably good agreement between the theory and experiment. For the sake of simplicity, a graphical technique was presented to obtain the melt depth of various materials at any arbitrary amount of power density and pulse duration. In the graphical technique, two dimensionless constants including the Stefan number (Ste) and an introduced constant named laser power factor (LPF) are used. Indeed, all of the internal and external parameters have been gathered in LPF. The effect of power density and pulse duration on the variation of melt depth for different materials such as aluminum, copper, and stainless steel were investigated. Additionally, appropriate expressions were extracted to describe the minimum power density and time to reach melting point in terms of process parameters. A simple expression is also extracted to estimate the thickness of mushy zone for alloys.
The assembly of kinesin-based nanotransport systems
Authors: Oliveira D. , Kim D.-M. , Umetsu M. , Kumagai I. , Adschiri T. , Teizer W.
Published: December 2012

At the nano-scale many proteins act as biological actuators for rotation or translation. Among these proteins, the building blocks of self-assembled, highly efficient natural motors, kinesin is considered a promising tool in the development of synthetic nanorobots. Conversion of chemical energy into mechanical work, harnessed by the hydrolysis of adenosine triphosphate, propels kinesin along a cytoplasmic system of fibers, known as a microtubule. Even though recent efforts were made to engineer tailor-made artificial nanotransport systems using kinesin, no systematic study investigated how these systems can be organized from the bottom up using the surface plasmon resonance technique. Here, we show that it is possible to quantitatively evaluate how each component of such nanoscopic machines is sequentially assembled by monitoring the individual association of its components, focusing specifically on the kinesin association to microtubules as well as the cargo-kinesin association. Furthermore, the kinetic parameters reported here for the microtubules and recombinant biotinylated kinesin binding process properties are of utmost importance due to the current widespread use of biotinylated kinesin in the construction of synthetic nano-machines.
Electron and spin transport studies of gated lateral organic devices
Authors: Alborghetti S. , Coey J. M. D. , Stamenov P.
Published: December 2012

In view of the many, often contradictory, reports of magneto-resistance (MR) in spin valve stacks containing a layer of organic semiconductor, mostly of the small molecule variety, we have investigated interdigitated lateral structures with an organic layer deposited in the narrow gap between two ferromagnetic electrodes, which are well-suited for studying charge and spin transport in novel (high resistivity) semiconducting materials. For the channel material we used three different organic semiconductors, the small molecule tris-(8-hydroxyquinoline) aluminum (Alq3), single crystals of pentacene, and the conductive polymer poly(3-hexylthiophene) (P3HT). The channel length was 80 nm. Temperature-dependent current-voltage characteristics reveal that in all instances the current is limited by field-assisted thermionic injection over an energy barrier at the metal/organic interface. No measurable magneto-resistance was observed down to 7 K. The interface energy barrier, together with the vastly different electronic structure of metals and organics close to the Fermi level, preclude spin injection. Nonetheless, unlike the case of inorganic semiconductors, the insertion of an artificial tunnel barrier at the contact did not improve spin injection. Gate-dependent measurements exhibited short-channel effects and transistor operation with on/off ratios of 103, but no magneto-resistance. We suggest the observations are a consequence of the formation of bipolaron-states at increasing carrier concentration.
Anharmonic coupling of the CH-stretch and CH-bend vibrations of chloroform as studied by near-infrared electroabsorption spectroscopy
Authors: Nishida Jun , Shigeto Shinsuke , Yabumoto Sohshi , Hamaguchi Hiro-o
Published: December 2012

Combination bands that involve CH- or OH-stretch vibrations appear in the near-infrared (NIR) region (4000–10 000 cm−1). Because they arise from anharmonic coupling between the component fundamentals, detailed analysis of the frequency and intensity of NIR combination bands allows one to elucidate the mechanisms behind the vibrational coupling in the condensed phase in terms of mechanical and electrical anharmonicities. Nevertheless, little has been studied, in particular experimentally, on the origin of the combination band intensity. Here, we show that NIR electroabsorption (EA) spectroscopy, which directly probes the effects of an externally applied electric field on a combination band, can shed new light on anharmonic vibrational coupling through determination of the direction of the transition moment for the combination band. We studied the combination band of the CH-stretch (ν1) and CH-bend (ν4) modes of liquid chloroform. The electric-field induced absorbance change of the ν1 + ν4 combination band caused by reorientation of the chloroform molecule was measured at various χ angles, where χ is the angle between the direction of the applied electric field and the polarization of the incident IR light. We were able to detect an absorbance change as small as 5 × 10−8 for the combination band. Using the NIR EA spectra of the combination band together with those of the CH-stretch and bend fundamentals, the angle between the transition moment for the combination band and the permanent dipole moment was determined experimentally for the first time to be (79 ± 14)°. The present investigation indicates that the contribution of the CH-stretch mode to the mechanical anharmonicity is minor and that the CH-bend mode plays a dominant role in the mechanical part of the vibrational coupling between the two fundamentals. Furthermore, density functional theory calculations show that both the mechanical anharmonicity of the CH-bend mode and the electrical anharmonicity may contribute equally to the anharmonic coupling.
The RARE model: A generalized approach to random relaxation processes in disordered systems
Authors: Eliazar Iddo , Metzler Ralf
Published: December 2012

This paper introduces and analyses a general statistical model, termed the RAndom RElaxations (RARE) model, of random relaxation processes in disordered systems. The model considers excitations that are randomly scattered around a reaction center in a general embedding space. The model's input quantities are the spatial scattering statistics of the excitations around the reaction center, and the chemical reaction rates between the excitations and the reaction center as a function of their mutual distance. The framework of the RARE model is versatile and a detailed stochastic analysis of the random relaxation processes is established. Analytic results regarding the duration and the range of the random relaxation processes, as well as the model's thermodynamic limit, are obtained in closed form. In particular, the case of power-law inputs, which turn out to yield stretched exponential relaxation patterns and asymptotically Paretian relaxation ranges, is addressed in detail.
Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)
Authors: Sadia Cyril P. , Maria Laganapan Aleena , Agatha Tumanguil Mae , Estacio Elmer , Somintac Armando , Salvador Arnel , Que Christopher T. , Yamamoto Kohji , Tani Masahiko
Published: December 2012

Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.
Active diffraction gratings: Development and tests
Authors: Bonora S. , Frassetto F. , Zanchetta E. , Della Giustina G. , Brusatin G. , Poletto L.
Published: December 2012

We present the realization and characterization of an active spherical diffraction grating with variable radius of curvature to be used in grazing-incidence monochromators. The device consists of a bimorph deformable mirror on the top of which a diffraction grating with laminar profile is realized by UV lithography. The experimental results show that the active grating can optimize the beam focalization of visible wavelengths through its rotation and focus accommodation.
Pressure tuned ferroelectric reentrance in nano-BaTiO3 ceramics
Authors: Zhu J. L. , Lin S. , Feng S. M. , Wang L. J. , Liu Q. Q. , Jin C. Q. , Wang X. H. , Zhong C. F. , Li L. T. , Cao Wenwu
Published: December 2012

In nano-grain BaTiO3 ceramics, internal compressive stresses make the cubic phase more stable, while internal shear stresses stabilize rhombohedral and orthorhombic phases. The competition between internal compressive stresses and internal shear stresses gives a ferroelectric to paraelectric to ferroelectric reentrance phenomenon as a function of grain size. The pressure can be a tuning factor of reentrance behavior by controlling the interactions between external hydrostatic pressure and internal compressive stresses. These experimental phenomena can be well described by a modified Ginzburg-Landau-Devonshire thermodynamic theory.
Contactless electroreflectance study of the Fermi level pinning on GaSb surface in n-type and p-type GaSb Van Hoof structures
Authors: Kudrawiec R. , Nair H. P. , Latkowska M. , Misiewicz J. , Bank S. R. , Walukiewicz W.
Published: December 2012

Contactless electroreflectance (CER) has been applied to study the Fermi-level position on GaSb surface in n-type and p-type GaSb Van Hoof structures. CER resonances, followed by strong Franz-Keldysh oscillation of various periods, were clearly observed for two series of structures. This period was much wider (i.e., the built-in electric field was much larger) for n-type structures, indicating that the GaSb surface Fermi level pinning position is closer to the valence-band than the conduction-band. From analysis of the built-in electric fields in undoped GaSb layers, it was concluded that on GaSb surface the Fermi-level is located ∼0.2 eV above the valence band.
Origin of the redshift of the luminescence peak in InGaN light-emitting diodes exposed to Co-60 γ-ray irradiation
Authors: Li Y. L. , Wang X. J. , He S. M. , Zhang B. , Sun L. X. , Li Y. D. , Guo Q. , Chen C. Q. , Chen Z. H. , Lu W.
Published: December 2012

The redshift (∼54 meV) of the photoluminescence (PL) peak energy of blue InGaN/GaN light-emitting diodes exposed to 60Co γ-rays was observed. Time-resolved PL indicates that the PL radiative time increases along with irradiation does. The temperature-dependent PL and photoreflectance techniques show that γ-ray irradiance leads to higher carrier localization energies and larger Stokes' shift, respectively. These facts suggest that the redshifts of the PL peak emission introduced by γ-ray irradiance mainly originated from the enhancement of indium fluctuation. The cathodoluminescent images of the samples before and after γ-ray irradiation are compared to verify the results.
Generalized Klein-Kramers equations
Authors: Fa Kwok Sau
Published: December 2012

A generalized Klein-Kramers equation for a particle interacting with an external field is proposed. The equation generalizes the fractional Klein-Kramers equation introduced by Barkai and Silbey [J. Phys. Chem. B 104, 3866 (2000)10.1021/jp993491m]. Besides, the generalized Klein-Kramers equation can also recover the integro-differential Klein-Kramers equation for continuous-time random walk; this means that it can describe the subdiffusive and superdiffusive regimes in the long-time limit. Moreover, analytic solutions for first two moments both in velocity and displacement (for force-free case) are obtained, and their dynamic behaviors are investigated.
Sliding elastic lattice: An explanation of the motion of superconducting vortices
Authors: Yoon Young-noh , Lee Jonghee
Published: December 2012

We introduce a system where an elastic lattice of particles is moved slowly at a constant velocity under the influence of a local external potential, construct a rigid-body model through simplification processes, and show that the two systems produce similar results. Then, we apply our model to a superconducting vortex system and produce path patterns similar to the ones reported in Lee et al. [Phys. Rev. B 84, 060515(R) (2011)], suggesting that the reasoning of the simplification processes in this paper is a possible explanation of the experimentally observed phenomenon.
Hybrid models of molecular machines and the no-pumping theorem
Authors: Mandal Dibyendu , Jarzynski Christopher
Published: December 2012

Synthetic nanoscale complexes capable of mechanical movement are often studied theoretically using discrete-state models that involve instantaneous transitions between metastable states. A number of general results have been derived within this framework, including a “no-pumping theorem” that restricts the possibility of generating directed motion by the periodic variation of external parameters. Motivated by recent experiments using time-resolved vibrational spectroscopy [Panman et al., Science 328, 1255 (2010)10.1126/science.1187967], we introduce a more detailed and realistic class of models in which transitions between metastable states occur by finite-time, diffusive processes rather than sudden jumps. We show that the no-pumping theorem remains valid within this framework.
On a critical radiation density in the Friedmann equation
Authors: Baumgärtel Hellmut
Published: December 2012

The paper presents a classification of the basic types of admissible solutions of the general Friedmann equation with non-vanishing cosmological constant and for the case that radiation and matter do not couple. There are four distinct types. The classification uses first the discriminant of a polynomial of the third degree, closely related to the right hand side of the Friedmann equation. The decisive term is then a critical radiation density which can be calculated explicitly.
Programmable pulse generator based on programmable logic and direct digital synthesis
Authors: Suchenek M. , Starecki T.
Published: December 2012

The paper presents a new approach of pulse generation which results in both wide range tunability and high accuracy of the output pulses. The concept is based on the use of programmable logic and direct digital synthesis. The programmable logic works as a set of programmable counters, while direct digital synthesis (DDS) as the clock source. Use of DDS as the clock source results in stability of the output pulses comparable to the stability of crystal oscillators and quasi-continuous tuning of the output frequency.