bluuebunny/crossref_metadata_2025 huggingface dataset:
The End of an Era in International Financial Regulation? A Postcrisis Research Agenda
Authors: Helleiner Eric , Pagliari Stefano
Published: February 2011

The global financial crisis that erupted in summer 2007 has made the reform of international prudential financial regulation one of the top priorities of global public policy. Past scholarship has usefully explained the creation and strengthening of international financial standards with reference to three policy arenas: interstate, domestic, and transnational. Despite the accomplishments of this specialist literature, the recent crisis has revealed a number of limitations in the ways scholars have understood interstate power relations, the influence of domestic politics, and the significance of transnational actors within international financial regulatory politics. Taken together, developments in each of these three arenas suggest that researchers may also need to be prepared to shift from explaining the strengthening of official international standards to analyzing their weakening in the postcrisis world. The latter task will require scholars to devote more analytical attention to a wider set of international regulatory outcomes, including “informal regulatory convergence,” “regulatory fragmentation,” and especially “cooperative regulatory decentralization.”
Who Supports Global Economic Engagement? The Sources of Preferences in American Foreign Economic Policy
Authors: Milner Helen V. , Tingley Dustin H.
Published: February 2011

In this article we bring together opposing international relations theories to better understand U.S. foreign policy, in particular foreign trade and aid. Using votes in the U.S. House of Representatives from 1979–2004, we explore different theoretical predictions about preferences for foreign economic policy. We assess the impact of domestic factors, namely political economy and ideological preferences, versus foreign policy pressures. Our three main results highlight the differential effect of these factors in the two issue areas. First, aid preferences are as affected by domestic political economy factors as are trade preferences. Second, trade preferences, but not economic aid ones, are shaped by the president's foreign policy concerns; for economic aid, domestic political economy factors matter more than foreign policy ones. Third, aid preferences are shaped more by ideological factors than are trade ones, but ideology plays a different substantive role in each. Different constituencies support aid and trade. This finding has implications for foreign policy substitutability, “the internationalist coalition” in U.S. foreign policy, “statist” theories of foreign policy, and the connection between public opinion and legislative voting.
Explaining Public Support for the Use of Military Force: The Impact of Reference Point Framing and Prospective Decision Making
Authors: Perla Héctor
Published: February 2011

This article examines the determinants of public support for the use of military force. It puts forward a Framing Theory of Policy Objectives (FTPO), which contends that public support for military engagements depends on the public's perception of the policy's objective. However, it is difficult for the public to judge a policy's objective because they cannot directly observe a policy's true intention and influential political actors offer competing frames to define it. This framing contestation, carried out through the media, sets the public's decision-making reference point and determines whether the policy is perceived as seeking to avoid losses or to achieve gains. The FTPO predicts that support will increase when the public perceives policies as seeking to prevent losses and decrease when the public judges policies to be seeking gains. I operationalize and test the theory using content analysis of national news coverage and opinion polls of U.S. intervention in Central America during the 1980s. These framing effects are found to hold regardless of positive or negative valence of media coverage.
IS TRADITIONAL CONTRACEPTIVE USE IN MOLDOVA ASSOCIATED WITH POVERTY AND ISOLATION?
Authors: LYONS-AMOS MARK J. , DURRANT GABRIELE B. , PADMADAS SABU S.
Published: February 2011

This study investigates the correlates of traditional contraceptive use in Moldova, a poor country in Europe with one of the highest proportions of traditional contraceptive method users. The high reliance on traditional methods, particularly in the context of sub-replacement level fertility rate, has not been systematically evaluated in demographic research. Using cross-sectional data on a sub-sample of 6039 sexually experienced women from the 2005 Moldovan Demographic and Health Survey, this study hypothesizes that (a) economic and spatial disadvantages increase the likelihood of traditional method use, and (b) high exposure to family planning/reproductive health (FP/RH) programmes increases the propensity to modern method use. Multilevel multinomial models are used to examine the correlates of traditional method use controlling for exposure to sexual activity, socioeconomic and demographic characteristics and data structure. The results show that economic disadvantage increases the probability of traditional method use, but the overall effect is small. Although higher family planning media exposure decreases the reliance on traditional methods among younger women, it has only a marginal effect in increasing modern method use among older women. Family planning programmes designed to encourage women to switch from traditional to modern methods have some success – although the effect is considerably reduced in regions outside of the capital Chisinau. The study concludes that FP/RH efforts directed towards the poorest may have limited impact, but interventions targeted at older women could reduce the burden of unwanted pregnancies and abortions. Addressing differentials in accessing modern methods could improve uptake in rural areas.
Forced turbulent fountain flow behaviour
Authors: WILLIAMSON N. , ARMFIELD S. W. , LIN WENXIAN
Published: February 2011

Numerical simulations of turbulent fountain flow are used to investigate the important energy and mass transfer mechanisms present in the forced fountain flow regime, which has been reported to exist at Froude numbers (Fr) greater than 3. The flow is equivalent to a negatively buoyant jet with three flow streams, the inner upflow (IF), the outer downflow (OF) and the surrounding ambient fluid (AF). Simulation results are presented forFr= 4 and 7 at Reynolds numberRe= 3350. The mean fountain penetration height scales with the previously reported relationZm/R0= 2.46Fr, whereR0is the source radius, but the assumptions behind analytical derivations of the relation are not supported by the present results. The results suggest that the OF may be relatively well described by the dynamics of a pure line plume surrounding the IF but with higher entrainment owing to the unsteady pulsing behaviour of the flow entering the OF from the IF. The length scale for a pure plume appears to apply atFr= 7 in the OF and a degree of self-similarity exists. Comparisons with previous results suggest the IF is not fully developed atFr= 7 and entrainment into the IF from the OF may not occur untilFr> 15.
The Impact of the Global Crisis on Cuba's Economy and Social Welfare
Authors: MESA-LAGO CARMELO , VIDAL-ALEJANDRO PAVEL
Published: February 2011

The mechanisms by which the world economic crisis has been transmitted from developed to developing economies are conditioned by domestic factors that may attenuate or accentuate external economic shocks and their adverse social effects. Cuba is a special case: it is an open economy and hence vulnerable to trade-growth transmission mechanisms, but at the same time, it is a socialist economy with universal social services. This article reviews the literature, summarises Cuba's domestic socio-economic strengths and weaknesses prior to the crisis, evaluates the effects of the crisis on the macro-economic and social services indicators, assesses the government response and suggests alternative socio-economic policies.
The Inter-American Commission of Women and Women's Suffrage, 1920–1945
Authors: TOWNS ANN
Published: February 2011

In studies of the international dimensions of women's suffrage, the role of international organisations has been overlooked. This article examines the suffrage activities of the Pan-American Union (PAU), and in particular those of the Inter-American Commission of Women (IACW), between 1920 and 1945. Attentive to historical context, the examination suggests that international organisations can be both bearers of state interests and platforms for social movement interests. The article also argues that while not independent bureaucracies, the PAU and IACW nevertheless had some importance for suffrage that cannot be attributed either to their state members or to the suffragist movements.
Instability thresholds in the microwave heating model with exponential non-linearity
Authors: ALCOLADO ADAM , KOLOKOLNIKOV THEODORE , IRON DAVID
Published: February 2011

When ceramics are heated inside a microwave cavity, a well-known phenomenon is the occurrence of hot spots – localised regions of high temperature. This phenomenon was modelled by Kriegsmann ((1997),IMA J. Appl. Math. 59(2), pp. 123–146; (2001),IMA J. Appl. Math. 66(1), pp. 1–32) using a non-local evolution PDE. We investigate profile and the stability of hot spots in one and two dimensions by using Kriegsmann's model with exponential non-linearity. The linearised problem associated with hot-spot-type solutions possesses two classes of eigenvalues. The first type is the large eigenvalues associated with the stability of the hot-spot profile and in this particular model there cannot be instability associated with these eigenvalues. The second type is the small eigenvalues associated with translation invariance. We show that the hot spots can become unstable due to the presence of small eigenvalues, and we characterise the instability thresholds. In particular, we show that for the material with low heat conductivity (such as ceramics), and in the presence of a variable electric field, the hot spots are typically stable inside a plate (in two dimensions) but can become unstable for a slab (in one dimension) provided that the microwave power is sufficiently large. On the other hand, for materials with high heat conductivity, the interior hot spots are unstable and move to the boundary of the domain in either one or two dimensions. For materials with moderate heat conductivity, the stability of hot spots is determined by both the geometry and the electric field inside the microwave cavity.
Markers of susceptibility to acute rheumatic fever: the B-cell antigen D8/17 is not robust as a marker in South Africa
Authors: Walker Kathleen G. , Cooper Margaret , McCabe Karin , Hughes Jane , Mathiassen Wendy , Lawrenson John , Wilmshurst Jo M.
Published: February 2011

Background

Acute rheumatic fever and its chronic sequelae, rheumatic cardiac disease, and neuropsychiatric movement disorders, remain major public health problems in South Africa. Early identification and treatment of streptococcal pharyngitis in susceptible individuals would prevent rheumatic cardiac disease. The B-cell antigen D8/17 is a marker of susceptibility to rheumatic fever in some populations.

Methods and results

We assessed the significance of the D8/17 marker in a group of South Africans. Blood was collected from 107 individuals; 40 patients had previous confirmed rheumatic fever, 20 were first-degree relatives, and 47 were controls. The expression of D8/17 in each sample was analysed by flow cytometry. The mean proportion of B-cells that were D8/17 positive was 0.5% in the index cases, 0.47% in their relatives, and 0.27% in the controls. There was a significant difference between the index cases and the controls, p = 0.03, but the mean percentage positive in each group was very low.

Conclusions

Patients with a history of rheumatic fever had statistically increased expression of the D8/17 marker. However, the actual percentages in this observational study were markedly lower than in other populations, ranging from 0.14%–1.53% compared to 11.6%–39.3%. The D8/17 marker would be an impractical screening tool in the South African population.
Ongoing inflammation in children with rheumatic heart disease
Authors: Habeeb Nevin M. M. , Al Hadidi Iman S.
Published: February 2011

Aim of the work

To elucidate the hypothesis of ongoing inflammation in children with chronic rheumatic heart disease, and its possible consequences.

Subjects and methods

This study was conducted on 36 patients with a mean age of 12.63 years: six with acute rheumatic carditis, and 30 with chronic rheumatic heart disease. There were 15 age- and sex-matched children who served as a control group. All subjects underwent echocardiographic assessment of valvular involvement and left ventricular function. Laboratory investigations comprised lipid profile, high-sensitivity C-reactive protein, and homocysteine assay.

Results

High-sensitivity C-reactive protein was significantly elevated in patients with acute rheumatic carditis and in patients with chronic rheumatic heart disease (mean and standard deviation of 78.33, 156 micrograms per millilitre and 78.33, 23.17 micrograms per millilitre, respectively) as compared to the control group (mean and standard deviation of 5.83 and 2.79 micrograms per millilitre). High-sensitivity C-reactive protein correlated with the grade of mitral regurgitation (p less than 0.05). Homocysteine was significantly elevated in patients with acute carditis and patients with rheumatic heart disease as compared to the control group (their mean and standard deviation were 2.96, 0.476 nanograms per decilitre, 2.99, 1.48 nanograms per decilitre, and 1.717, 0.733 nanograms per decilitre, respectively), but did not show significant difference between the two studied groups of patients. Neither C-reactive protein nor homocysteine correlated with any of the studied parameters of lipid profile.

Conclusion

There is evidence of ongoing inflammation in children with rheumatic heart disease, which correlates with the degree of valvular involvement. This ongoing inflammation may put those children at risk for premature atherosclerosis.
John Searle on the concept of political power, the power of states and war-making: why states demand a monopoly of the organisation and use of soldiers
Authors: GRAN THORVALD
Published: February 2011

John Searle has developed a strong theory of how speech acts and agreements generate institutions. How is the general theory specified for political institutions? He, like Max Weber, suggests that a government monopoly of soldiers is a condition for the existence of political institutions. However, governments' wielding of force is only political if those attacked consider the attack a responsible and a morally acceptable act. All political power in Searle's theory is deontic. It is assigned as a right, an obligation or the like, as a status function. If power wielding by a government is not assigned, it is beyond the political; it is only brute force. My contention is that this distinction limits the power of Searle's theory in the analysis of politics. From the idea of political institutions as ultimate institutions in a specific, bordered territory it is the strong idea of deonticity that is misleading. Ultimate institutions cannot by definition have externally assigned status. Leaders of other ultimate institutions can accept their existence, but then mainly because they have the military power to defend their borders. Nation states, demanding territorial sovereignty, therefore logically demand a monopoly of soldiers. This sovereignty seen over time suggests an evolutionary first principle of political institutions.
Which institutions matter? Separating the chaff from the wheat
Authors: JOHN ARIELLE , STORR VIRGIL HENRY
Published: February 2011

Ha-Joon Chang (2011), in his article ‘Institutions and Economic Development: Theory, Policy and History’, argues that economists place too much faith in ‘liberalized’ institutions. Institutions matter for growth, he contends, but not the way institutional economists think they do. In this article, we offer a defense of the hypothesis that ‘institutions matter’ for economic growth and present several objections to Chang's arguments.
Institutions first
Authors: BOETTKE PETER , FINK ALEXANDER
Published: February 2011

Ha-Joon Chang, in his article ‘Institutions and Economic Development: Theory, Policy and History’, raises doubts about the effects of institutions on economic development and questions the positive effects of entirely free markets based on secure private property rights. We respond by stressing that institutions structure the incentives underlying individual action, secure private property rights are indispensable for prosperity, institutions have a first-order effect whereas policies only have a second-order effect, successful institutional change comes from within a society, and, given the status quo of developing countries, first-world institutions are likely not to be available to them.
Poverty of stimulus and absence of cause: some questions for Felin and Foss
Authors: HODGSON GEOFFREY M. , KNUDSEN THORBJØRN
Published: February 2011

We examine an aspect of the argument of Teppo Felin and Nicolai Foss (‘The Endogenous Origins of Experience, Routines, and Organizational Capabilities: The Poverty of Stimulus’; 2011) where they reject the claim of Geoffrey Hodgson and Thorbjørn Knudsen (‘Darwinism, Causality and the Social Sciences’; 2004) that habits depend crucially on stimuli from the social environment. We argue that while rightly stressing human agency they also create a false dichotomy between agential and environmental factors in the explanation. Felin and Foss create further confusion by hinting – without adequate clarification – at an untenable notion of human agency as an uncaused cause. We raise several questions of clarification for these authors.
Emotional Empathy and Facial Reactions to Facial Expressions
Authors: Dimberg Ulf , Andréasson Per , Thunberg Monika
Published: February 2011

This study investigates whether people high in emotional empathy are more facially reactive than are people low in emotional empathy when exposed to pictures of angry and happy facial expressions. Facial electromyographic activity was measured from the corrugator and the zygomatic muscle regions. In accordance with the predictions, the high empathic group reacted with larger corrugator activity to angry as compared to happy faces and with larger zygomatic activity to happy faces. However, the low empathic group did not differentiate between the angry and happy stimuli at all. The high empathic group, as compared to the low empathic group, also rated the angry faces as expressing more anger and the happy faces as being happier. It is concluded that high empathic people are particularly sensitive in reacting with facial reactions to facial expressions and that this ability is accompanied by a higher level of empathic accuracy.
The Role of Sensory Gating in the Racism/Blood Pressure Relationship
Authors: Peters Rosalind M. , Butler Karyn , Gjini Klevest , Yeragani Vikram , Boutros Nash N.
Published: February 2011

African Americans bear a disproportionate burden of hypertension with racism postulated as a unique stressor contributing to the noted disparities. Epidemiological studies have found differences in the prevalence of hypertension among African Americans based on the amount of perceived racism reported, and experimental studies have shown increased cardiovascular reactivity to racially-aversive stressors. A difference in individual response to racial stressors may create subgroups of African Americans at highest risk for hypertension and its complications. Although sensory gating is the brain’s capacity to selectively regulate its sensitivity to environmental sensory stimuli, scant research has been done regarding the role of sensory gating in the stress response, and no research has explored sensory gating with racial stressors. To address this gap, we examined whether P50 sensory gating was associated with cardiovascular and central nervous system responses to an experimentally-induced racial stressor among 15 African Americans. A paired-click paradigm was administered prior to the experimental condition, which involved exposure to a neutral and then a racially-aversive photo stimulus. Participants with weak gating showed a significant within-subjects decrease in alpha-band activity when viewing the racially aversive stimulus and had significantly decreased alpha activity when viewing the aversive stimuli compared to participants with strong gating. Increased cardiovascular reactivity occurred with the aversive stimulus, and gender differences were noted. A gating effect on cardiovascular reactivity could not be determined given the small sample size and the fact that few men qualified as having ‘good’ gating. Although subjects reported no conscious awareness of distress when viewing the racially-aversive stimulus, both cardiovascular and central nervous system reactions occurred, with the responses varying based on the level of sensory gating. These results suggest sensory gating as a potential physiologic factor that may influence the relationship between perceived racial stressors and health outcomes.
Exploiting T cells specific for human minor histocompatibility antigens for therapy of leukemia
Authors: Bleakley Marie , Riddell Stanley R
Published: February 2011

Minor histocompatibility (H) antigens are major targets of a graft‐versus‐leukemia (GVL) effect mediated by donor CD8+ and CD4+ T cells following allogeneic hematopoietic cell transplantation (HCT) between human leukocyte antigen identical individuals. In the 15 years since the first molecular characterization of human minor H antigens, significant strides in minor H antigen discovery have been made as a consequence of advances in cellular, genetic and molecular techniques. Much has been learned about the mechanisms of minor H antigen immunogenicity, their expression on normal and malignant cells, and their role in GVL responses. T cells specific for minor H antigens expressed on leukemic cells, including leukemic stem cells, can be isolated and expanded in vitro and infused into allogeneic HCT recipients to augment the GVL effect to prevent and treat relapse. The first report of the adoptive transfer of minor H antigen‐specific T‐cell clones to patients with leukemic relapse in 2010 illustrates the potential for the manipulation of alloreactivity for therapeutic benefit. This review describes the recent developments in T‐cell recognition of human minor H antigens, and efforts to translate these discoveries to reduce leukemia relapse after allogeneic HCT.
Understanding human T‐cell‐mediated immunoregulation through herpesviruses
Authors: Burrows Scott R , Moss Denis J , Khanna Rajiv
Published: February 2011

Human herpesviruses have coevolved with humans over millions of years, and adaptation of latent infection within the cells of the immune system is a unique characteristic of many of these viruses. Following primary infection, these herpesviruses establish an asymptomatic‐persistent infection in healthy individuals that is strictly controlled by virus‐specific CD8+ and CD4+ T cells. Here, we provide a brief overview of how the human immune system interacts with these latent viruses and regulates the lifelong host–virus relationship in healthy virus carriers. Extensive studies on T‐cell‐mediated immune regulation over the last decade has allowed researchers to successfully translate these findings into the clinical setting to treat various herpesvirus‐associated diseases in transplant patients and individuals with virus‐associated malignancies. It is highly likely that these newly emerging T‐cell‐based therapeutic and diagnostic technologies will revolutionize the clinical management of patients with herpesvirus‐associated diseases.
Bias in the αβ T‐cell repertoire: implications for disease pathogenesis and vaccination
Authors: Miles John J , Douek Daniel C , Price David A
Published: February 2011

The naïve T‐cell repertoire is vast, containing millions of unique T‐cell receptor (TCR) structures. Faced with such diversity, the mobilization of TCR structures from this enormous pool was once thought to be a stochastic, even chaotic, process. However, steady and systematic dissection over the last 20 years has revealed that this is not the case. Instead, the TCR repertoire deployed against individual antigens is routinely ordered and biased. Often, identical and near‐identical TCR repertoires can be observed across different individuals, suggesting that the system encompasses an element of predictability. This review provides a catalog of αβ TCR bias by disease and by species, and discusses the mechanisms that govern this inherent and widespread phenomenon.
The structural bases of direct T‐cell allorecognition: implications for T‐cell‐mediated transplant rejection
Authors: Gras Stephanie , Kjer‐Nielsen Lars , Chen Zhenjun , Rossjohn Jamie , McCluskey James
Published: February 2011

αβ T‐cell receptors (TCRs), which can engage a broad array of foreign peptide‐laden major histocompatibility complex (pMHC) landscapes, have an essential role in protective immunity. TCRs are selected by pMHC molecules in the thymus and in the periphery, and so are restricted to recognizing ‘self’‐major histocompatibility complex (MHC) molecules. Accordingly, T cells are inherently cross‐reactive, and although the versatility and specificity of this MHC‐restricted response are the hallmarks of adaptive immunity, ‘unwanted’ TCR interactions, such as those observed in T‐cell alloreactivity, often occur. Recent data have shown that direct T‐cell alloreactivity can arise from peptide‐dependent molecular mimicry, as well as distinct pMHC‐binding modes. Here we review recent advances in the field, focusing on structural data pertaining to alloreactivity, and discuss the implications for T‐cell‐mediated transplant rejection.
Mice with human immune system components as in vivo models for infections with human pathogens
Authors: Rämer Patrick C , Chijioke Obinna , Meixlsperger Sonja , Leung Carol S , Münz Christian
Published: February 2011

Many pathogens relevant to human disease do not infect other animal species. Therefore, animal models that reconstitute or harbor human tissues are explored as hosts for these. In this review, we will summarize recent advances to utilize mice with human immune system components, reconstituted from hematopoietic progenitor cells in vivo. Such mice can be used to study human pathogens that replicate in leukocytes. In addition to studying the replication of these pathogens, the reconstituted human immune system components can also be analyzed for initiating immune responses and control against these infections. Moreover, these new animal models of human infectious disease should replicate the reactivity of the human immune system to vaccine candidates and, especially, the adjuvants contained in them, more faithfully.
Tensor decomposition in post-Hartree–Fock methods. I. Two-electron integrals and MP2
Authors: Benedikt Udo , Auer Alexander A. , Espig Mike , Hackbusch Wolfgang
Published: February 2011

A new approximation for post-Hartree–Fock (HF) methods is presented applying tensor decomposition techniques in the canonical product tensor format. In this ansatz, multidimensional tensors like integrals or wavefunction parameters are processed as an expansion in one-dimensional representing vectors. This approach has the potential to decrease the computational effort and the storage requirements of conventional algorithms drastically while allowing for rigorous truncation and error estimation. For post-HF ab initio methods, for example, storage is reduced to \documentclass[12pt]{minimal}\begin{document}$\mathcal O({d \cdot R \cdot n})$\end{document}O(d·R·n) with d being the number of dimensions of the full tensor, R being the expansion length (rank) of the tensor decomposition, and n being the number of entries in each dimension (i.e., the orbital index). If all tensors are expressed in the canonical format, the computational effort for any subsequent tensor contraction can be reduced to \documentclass[12pt]{minimal}\begin{document}$\mathcal O({R^{2} \cdot n})$\end{document}O(R2·n). We discuss details of the implementation, especially the decomposition of the two-electron integrals, the AO–MO transformation, the Møller–Plesset perturbation theory (MP2) energy expression and the perspective for coupled cluster methods. An algorithm for rank reduction is presented that parallelizes trivially. For a set of representative examples, the scaling of the decomposition rank with system and basis set size is found to be \documentclass[12pt]{minimal}\begin{document}$\mathcal O({N^{1.8}})$\end{document}O(N1.8) for the AO integrals, \documentclass[12pt]{minimal}\begin{document}$\mathcal O({N^{1.4}})$\end{document}O(N1.4) for the MO integrals, and \documentclass[12pt]{minimal}\begin{document}$\mathcal O({N^{1.2}})$\end{document}O(N1.2) for the MP2 t2-amplitudes (N denotes a measure of system size) if the upper bound of the error in the ℓ2-norm is chosen as ε = 10−2. This leads to an error in the MP2 energy in the order of mHartree.
Fiber optic sensing technology for detecting gas hydrate formation and decomposition
Authors: Rawn C. J. , Leeman J. R. , Ulrich S. M. , Alford J. E. , Phelps T. J. , Madden M. E.
Published: February 2011

A fiber optic-based distributed sensing system (DSS) has been integrated with a large volume (72 l) pressure vessel providing high spatial resolution, time-resolved, 3D measurement of hybrid temperature–strain (TS) values within experimental sediment–gas hydrate systems. Areas of gas hydrate formation (exothermic) and decomposition (endothermic) can be characterized through this proxy by time series analysis of discrete data points collected along the length of optical fibers placed within a sediment system. Data are visualized as an animation of TS values along the length of each fiber over time. Experiments conducted in the Seafloor Process Simulator at Oak Ridge National Laboratory clearly indicate hydrate formation and dissociation events at expected pressure-temperature conditions given the thermodynamics of the CH4–H2O system. The high spatial resolution achieved with fiber optic technology makes the DSS a useful tool for visualizing time-resolved formation and dissociation of gas hydrates in large-scale sediment experiments.
A weighted reverse Cuthill–McKee procedure for finite element method algorithms to solve strongly anisotropic electrodynamic problems
Authors: Cristofolini Andrea , Latini Chiara , Borghi Carlo A.
Published: February 2011

This paper presents a technique for improving the convergence rate of a generalized minimum residual (GMRES) algorithm applied for the solution of a algebraic system produced by the discretization of an electrodynamic problem with a tensorial electrical conductivity. The electrodynamic solver considered in this work is a part of a magnetohydrodynamic (MHD) code in the low magnetic Reynolds number approximation. The code has been developed for the analysis of MHD interaction during the re-entry phase of a space vehicle. This application is a promising technique intensively investigated for the shock mitigation and the vehicle control in the higher layers of a planetary atmosphere. The medium in the considered application is a low density plasma, characterized by a tensorial conductivity. This is a result of the behavior of the free electric charges, which tend to drift in a direction perpendicular both to the electric field and to the magnetic field. In the given approximation, the electrodynamics is described by an elliptical partial differential equation, which is solved by means of a finite element approach. The linear system obtained by discretizing the problem is solved by means of a GMRES iterative method with an incomplete LU factorization threshold preconditioning. The convergence of the solver appears to be strongly affected by the tensorial characteristic of the conductivity. In order to deal with this feature, the bandwidth reduction in the coefficient matrix is considered and a novel technique is proposed and discussed. First, the standard reverse Cuthill–McKee (RCM) procedure has been applied to the problem. Then a modification of the RCM procedure (the weighted RCM procedure, WRCM) has been developed. In the last approach, the reordering is performed taking into account the relation between the mesh geometry and the magnetic field direction. In order to investigate the effectiveness of the methods, two cases are considered. The RCM and WRCM procedures has successfully improved the convergence rate of the GMRES solver. For strong anisotropies, the WRCM procedure appears to have a higher convergence rate. The same behavior is shown when applying the methods to the rebuilding of an hypersonic MHD experiment.
A quantitative analysis of photocurrent signals measured on GaAs using conductive atomic force microscopy
Authors: Eckhardt C. , Madl M. , Brezna W. , Smoliner J.
Published: February 2011

In this work, photocurrent (PC) spectra on GaAs measured by conductive atomic force microscope (AFM) tips are analyzed quantitatively. The measurements were carried out on n-doped bulk GaAs samples as a function of excitation wavelength and tip bias. The measured data are compared to simulations employing a two-dimensional self consistent POISSON SOLVER. It is found that the shape of the depletion zone below the AFM tip is strongly influenced by the tip bias and the surface potential, which leads to a clear difference between PC data obtained with large area devices and conductive AFM tips.
Interaction potential for aluminum nitride: A molecular dynamics study of mechanical and thermal properties of crystalline and amorphous aluminum nitride
Authors: Vashishta Priya , Kalia Rajiv K. , Nakano Aiichiro , Rino José Pedro ,   Collaboratory for Advanced Computing and Simulations
Published: February 2011

An effective interatomic interaction potential for AlN is proposed. The potential consists of two-body and three-body covalent interactions. The two-body potential includes steric repulsions due to atomic sizes, Coulomb interactions resulting from charge transfer between atoms, charge-induced dipole-interactions due to the electronic polarizability of ions, and induced dipole–dipole (van der Waals) interactions. The covalent characters of the Al–N–Al and N–Al–N bonds are described by the three-body potential. The proposed three-body interaction potential is a modification of the Stillinger–Weber form proposed to describe Si. Using the molecular dynamics method, the interaction potential is used to study structural, elastic, and dynamical properties of crystalline and amorphous states of AlN for several densities and temperatures. The structural energy for wurtzite (2H) structure has the lowest energy, followed zinc-blende and rock-salt (RS) structures. The pressure for the structural transformation from wurtzite-to-RS from the common tangent is found to be 24 GPa. For AlN in the wurtzite phase, our computed elastic constants (C11, C12, C13, C33, C44, and C66), melting temperature, vibrational density-of-states, and specific heat agree well with the experiments. Predictions are made for the elastic constant as a function of density for the crystalline and amorphous phase. Structural correlations, such as pair distribution function and neutron and x-ray static structure factors are calculated for the amorphous and liquid state.
Temperature-dependent structure of methyltributylammonium bis(trifluoromethylsulfonyl)amide: X ray scattering and simulations
Authors: Santos Cherry S. , Annapureddy Harsha V. R. , Murthy N. Sanjeeva , Kashyap Hemant K. , Castner Edward W. , Margulis Claudio J.
Published: February 2011

We report the combined results of computational and x ray scattering studies of amorphous methyltributylammonium bis(trifluoromethylsulfonyl)amide as a function of temperature. These studies included the temperature range for the normal isotropic liquid, a deeply supercooled liquid and the glass. The low q peaks in the range from 0.3 to 1.5 Å−1 in the structure function of this liquid can be properly accounted for by correlations between first and second nearest neighbors. The lowest q peak can be assigned to real space correlations between ions of the same charge, while the second peak arises mostly from nearest neighbors of opposite charge. Peaks at larger q values are mostly intramolecular in nature. While our simulated structure functions provide an excellent match to our experimental results and our experimental findings agree with previous studies reported for this liquid, the prior interpretation of the experimental data in terms of an interdigitated smectic A phase is not supported by our simulations. In this work, we introduce a set of general theoretical partitions of real and reciprocal space correlations that allow for unambiguous analysis of all intra- and interionic contributions to the structure function and coherent scattering intensity. We find that the intermolecular contributions to the x ray scattering intensity are dominated by the anions and cross terms between cations and anions for this ionic liquid.
Causal electromagnetic interaction equations
Authors: Zinoviev Yury M.
Published: February 2011

For the electromagnetic interaction of two particles the relativistic causal quantum mechanics equations are proposed. These equations are solved for the case when the second particle moves freely. The initial wave functions are supposed to be smooth and rapidly decreasing at the infinity. This condition is important for the convergence of the integrals similar to the integrals of quantum electrodynamics. We also consider the singular initial wave functions in the particular case when the second particle mass is equal to zero. The discrete energy spectrum of the first particle wave function is defined by the initial wave function of the free-moving second particle. Choosing the initial wave functions of the free-moving second particle it is possible to obtain a practically arbitrary discrete energy spectrum.
Bias effects on the electronic spectrum of a molecular bridge
Authors: Phillips Heidi , Prociuk Alexander , Dunietz Barry D.
Published: February 2011

In this paper the effect of bias and geometric symmetry breaking on the electronic spectrum of a model molecular system is studied. Geometric symmetry breaking can either enhance the dissipative effect of the bias, where spectral peaks are disabled, or enable new excitations that are absent under zero bias conditions. The spectral analysis is performed on a simple model system by solving for the electronic response to an instantaneously impulsive perturbation in the dipole approximation. The dynamical response is extracted from the electronic equations of motion as expressed by the Keldysh formalism. This expression provides for the accurate treatment of the electronic structure of a bulk-coupled system at the chosen model Hamiltonian electronic structure level.
High-throughput measurement of rice tillers using a conveyor equipped with x-ray computed tomography
Authors: Yang Wanneng , Xu Xiaochun , Duan Lingfeng , Luo Qingming , Chen Shangbin , Zeng Shaoqun , Liu Qian
Published: February 2011

Tillering is one of the most important agronomic traits because the number of shoots per plant determines panicle number, a key component of grain yield. The conventional method of counting tillers is still manual. Under the condition of mass measurement, the accuracy and efficiency could be gradually degraded along with fatigue of experienced staff. Thus, manual measurement, including counting and recording, is not only time consuming but also lack objectivity. To automate this process, we developed a high-throughput facility, dubbed high-throughput system for measuring automatically rice tillers (H-SMART), for measuring rice tillers based on a conventional x-ray computed tomography (CT) system and industrial conveyor. Each pot-grown rice plant was delivered into the CT system for scanning via the conveyor equipment. A filtered back-projection algorithm was used to reconstruct the transverse section image of the rice culms. The number of tillers was then automatically extracted by image segmentation. To evaluate the accuracy of this system, three batches of rice at different growth stages (tillering, heading, or filling) were tested, yielding absolute mean absolute errors of 0.22, 0.36, and 0.36, respectively. Subsequently, the complete machine was used under industry conditions to estimate its efficiency, which was 4320 pots per continuous 24 h workday. Thus, the H-SMART could determine the number of tillers of pot-grown rice plants, providing three advantages over the manual tillering method: absence of human disturbance, automation, and high throughput. This facility expands the application of agricultural photonics in plant phenomics.
Comparison between Einstein and Debye models for an amorphous Ni46Ti54 alloy produced by mechanical alloying investigated using extended x-ray absorption fine structure and cumulant expansion
Authors: Machado K. D.
Published: February 2011

We investigated an amorphous Ni46Ti54 alloy produced by mechanical alloying using extended x-ray absorption fine structure (EXAFS) technique and cumulant expansion considering Einstein and Debye models for the temperature dependence of the cumulants. Results obtained from both models were compared and very similar values were obtained. From them, we found information about the structure of the alloy besides thermal and structural disorder, anharmonicity, thermal expansion, and asymmetry of the partial distribution functions gij(r). The cumulants \documentclass[12pt]{minimal}\begin{document}$C_1^*$\end{document}C1*, \documentclass[12pt]{minimal}\begin{document}$C_2^*$\end{document}C2*, and \documentclass[12pt]{minimal}\begin{document}$C_3^*$\end{document}C3* also allowed us to reconstruct the gij(r, T) functions from EXAFS.
Mg2H2: New insight on the Mg–Mg bonding and spectroscopic study
Authors: Brites V. , Guitou M. , Léonard C.
Published: February 2011

The six dimensional potential energy surface of the electronic ground state ${\rm \tilde X}\,$X̃1Σg+ of Mg2H2 has been generated by the coupled-cluster approach with single, double and perturbative triple excitations [CCSD(T)] combined with the aug-cc-pCVTZ basis set for Mg atoms and the aug-cc-pVTZ basis set for the H atoms. The analytical representation of this surface was used in variational calculations of the rovibrational energies of Mg2H2, Mg2D2, and HMg2D for J = 0 and 1. For Mg2H2, the rotational constant B0 is computed to be 0.1438 cm−1, and the fundamental anharmonic wavenumbers are calculated to be ν1 = 1527.3 cm−1 (Σg+), ν2 = 275.3 cm−1 (Σg+), ν3 = 1503.6 cm−1 (Σu+), ν4 = 312.9 cm−1 (Πg), and ν5 = 256.5 cm−1 (Πu). In addition, the electronic ground states of Mg2H, MgH2, Mg2, and MgH have been investigated in order to compute the bonding energies of Mg2H2 and to explain the strength of the Mg–Mg bond in this tetra-atomic molecule. The nature of the low-lying excited states of Mg2H2 is also studied.
Vibrational coupled cluster response theory: A general implementation
Authors: Seidler Peter , Sparta Manuel , Christiansen Ove
Published: February 2011

The calculation of vibrational contributions to molecular properties using vibrational coupled cluster (VCC) response theory is discussed. General expressions are given for expectation values, linear response functions, and transition moments. It is shown how these expressions can be evaluated for arbitrary levels of excitation in the wave function parameterization as well as for arbitrary coupling levels in the potential and property surfaces. The convergence of the method is assessed by benchmark calculations on formaldehyde. Furthermore, excitation energies and infrared intensities are calculated for the fundamental vibrations of furan using VCC limited to up to two-mode and up to three-mode excitations, VCC[2] and VCC[3], as well as VCC with full two-mode and approximate three-mode couplings, VCC[2pt3].
Orientational correlations in two-dimensional liquid crystals studied by molecular dynamics simulation
Authors: Watanabe Go , Saito Jun-Ichi , Kato Nobuyuki , Tabe Yuka
Published: February 2011

Orientational correlations in Langmuir monolayers of nematic and smectic-C liquid crystal (LC) phases are investigated by molecular dynamics simulation. In both phases, the orientational correlation functions decay algebraically yet with the different exponents of 1.9 and 0.2 for the nematic and the smectic-C monolayers, respectively. The power law decay, i.e., the absence of long-range orientational order, means the both monolayers should be the ideal 2D system with a continuous symmetry, whereas the large difference in the exponents of power law gives rise to the crucial difference in their optical properties; the nematic monolayer is optically isotropic while the smectic-C monolayer exhibits an anisotropy on the length scale of visible light. Since the exponent is inversely proportional to the molecular exchange energy, the averaged molecular interaction in the nematic monolayer should be an order of magnitude smaller than that in the smectic-C monolayer, which is ascribed to the low molecular density and the weak molecular dipole due to the water molecule. The relation between the molecular interaction and the orientational correlation calculated for the 2D LC system offers much information not only about the 2D LCs but also on the bulk system.
The spin-free analogue of Mukherjee's state-specific multireference coupled cluster theory
Authors: Datta Dipayan , Mukherjee Debashis
Published: February 2011

In this paper, we develop a rigorously spin-adapted version of Mukherjee's state-specific multireference coupled cluster theory (SS-MRCC, also known as Mk-MRCC) [U. S. Mahapatra, B. Datta, and D. Mukherjee, J. Chem. Phys. 110, 6171 (1999)] for reference spaces comprising open-shell configurations. The principal features of our approach are as follows: (1) The wave operator Ω is written as Ω = ∑μΩμ|ϕμ〉cμ, where {ϕμ} is the set of configuration state functions spanning a complete active space. (2) In contrast to the Jeziorski–Monkhorst Ansatz in spin-orbital basis, we write Ωμ as a power series expansion of cluster operators Rμ defined in terms of spin-free unitary generators. (3) The operators Rμ are either closed-shell-like n hole-n particle excitations (denoted as Tμ) or they involve valence (active) destruction operators (denoted as Sμ); these latter type of operators can have active–active scatterings, which can also carry the same active orbital labels (such Sμ’s are called to have spectator excitations). (4) To simulate multiple excitations involving powers of cluster operators, we allow the Sμ’s carrying the same active orbital labels to contract among themselves. (5) We exclude Sμ’s with direct spectator scatterings. (6) Most crucially, the factors associated with contracted composites are chosen as the inverse of the number of ways the Sμ’s can be joined among one another leading to the same excitation. The factors introduced in (6) have been called the automorphic factors by us. One principal thrust of this paper is to show that the use of the automorphic factors imparts a remarkable simplicity to the final amplitude equations: the equations consist of terms that are at most quartic in cluster amplitudes, barring only a few. In close analogy to the Mk-MRCC theory, the inherent linear dependence of the cluster amplitudes leading to redundancy is resolved by invoking sufficiency conditions, which are exact spin-free analogues of the spin-orbital based Mk-MRCC theory. This leads to manifest size-extensivity and an intruder-free formulation. Our formalism provides a relaxed description of the nondynamical correlation in presence of dynamical correlation. Pilot numerical applications to doublet systems, e.g., potential energy surfaces for the first two excited 2A' states of asymmetric H2S+ ion and the ground 2Σ+state of BeH radical are presented to assess the viability of our formalism over an wide range of nuclear geometries and the manifest avoidance of intruder state problem.