bluuebunny/crossref_metadata_2025 huggingface dataset:
Antecedents of Online Reviews’ Usage and Purchase Influence: An Empirical Comparison of U.S. and Korean Consumers
Authors: Park Cheol , Lee Thae Min
Published: January 2010

We propose a model linking consumer characteristics (consumer susceptibility to interpersonal influence and Internet shopping experience), attitude toward online reviews (perceived usefulness), and the outcome of online reviews (usage frequency and purchase influence). We advance hypotheses on the interrelationships among these factors and on the moderating effects of national culture on some of the relationships. We test the hypotheses on survey data collected from U.S. and Korean consumers. The results show that national culture has important moderating effects on the relationships among online reviews and its antecedents. The results suggest that an attitude-oriented marketing communication strategy is more effective for Korean consumers while a behavior-oriented strategy is more effective for U.S. consumers.
An Experimental Study of the Relationship between Online Engagement and Advertising Effectiveness
Authors: Calder Bobby J. , Malthouse Edward C. , Schaedel Ute
Published: January 2010

We discuss consumer engagement with a website, provide a systematic approach to examining the types of engagement produced by specific experiences, and show that engagement with the media context increases advertising effectiveness. Based on experiments using measurement scales involving eight different online experiences, we advance two types of engagement with online media — Personal and Social-Interactive Engagement. Our results show that both types are positively associated with advertising effectiveness. Moreover, Social-Interactive Engagement, which is more uniquely characteristic of the web as a medium, is shown to affect advertising after controlling for Personal Engagement. Our results offer online companies and advertisers new metrics and advertising strategies.
Does Chatter Matter? The Impact of User-Generated Content on Music Sales
Authors: Dhar Vasant , Chang Elaine A.
Published: January 2010

The Internet has enabled a new era of user-generated content, threatening the hegemony of traditional content generators as the primary sources of “legitimate” information. In this study, we examine the usefulness of such content, consisting of data from blogs and social networking sites, in predicting sales in the music industry. We track changes in online chatter for a sample of 108 albums for four weeks before and after their release dates. We identify the significance of variables on the observation date in predicting future album unit sales one, two, and three weeks ahead. Our findings are that future sales are positively correlated with (a) the volume of blog posts about an album, and (b) traditional factors such as whether the album is released by a major label and reviews from mainstream sources like Rolling Stone. More generally, the study provides some preliminary answers for marketing managers interested in assessing the relative importance of the burgeoning number of “Web 2.0” information metrics that are becoming available on the Internet. The study also provides a framework for thinking about when user-generated content influences decision making.
Food intake patterns associated with carotid artery atherosclerosis in the Insulin Resistance Atherosclerosis Study
Authors: Liese Angela D. , Nichols Michele , Hodo Denise , Mellen Philip B. , Schulz Mandy , Goff David C. , D'Agostino Ralph B.
Published: January 2010

We aimed to identify food intake patterns that operate via haemostatic and inflammatory pathways on progression of atherosclerosis among 802 middle-aged adults with baseline and 5-year follow-up ultrasound measurements of common (CCA) and internal carotid artery (ICA) intimal medial thickness (IMT). Food intake was ascertained with an FFQ. We derived food patterns using reduced rank regression (RRR) with plasminogen activator inhibitor 1 and fibrinogen as response variables. We explored the impact of various food pattern simplification approaches. We identified a food pattern characterised by higher intakes of less healthful foods (low-fibre bread and cereal, red and processed meat, cottage cheese, tomato foods, regular soft drinks and sweetened beverages) and lower intakes of more healthful foods (wine, rice and pasta, meal replacements and poultry). The pattern was positively associated with mean CCA IMT at follow-up (P = 0·0032), a 1 sd increase corresponding to an increase of 13 μm higher CCA IMT at follow-up, adjusted for demographic and cardiovascular risk factors. With increasing pattern quartile (Q), the percentage change in CCA IMT increased significantly: Q1 0·8 %; Q2 3·2 %; Q3 8·6 %; Q4 7·9 % (P = 0·0045). No clear association with ICA IMT was observed. All simplification methods yielded similar results. The present results support the contention that a pro-inflammatory and pro-thrombotic dietary pattern increases the rate of coronary artery atherosclerosis progression, independent of traditional cardiovascular risk factors. RRR is a promising and robust tool for moving beyond the previous focus on nutrients or foods into research on the health effects of broader dietary patterns.
Efficiency of different marker systems for molecular characterization of subtropical carrot germplasm
Authors: JHANG T. , KAUR M. , KALIA P. , SHARMA T. R.
Published: January 2010

Genetic variability in carrots is a consequence of allogamy, which leads to a high level of inbreeding depression, affecting the development of new varieties. To understand the extent of genetic variability in 40 elite indigenous breeding lines of subtropical carrots, 48 DNA markers consisting of 16 inter simple sequence repeats (ISSRs), 10 universal rice primers (URPs), 16 random amplification of polymorphic DNA (RAPD) and six simple sequence repeat (SSR) markers were used. These 48 markers amplified a total of 591 bands, of which 569 were polymorphic (0·96). Amplicon size ranged from 200 to 3500 base pairs (bp) in ISSR, RAPD and URPs markers and from 100 to 300 bp in SSR markers. The ISSR marker system was found to be most efficient with (GT)nmotifs as the most abundant SSR loci in the carrot genome. The unweighted pair group method with arithmetic mean (UPGMA) analysis of the combined data set of all the DNA markers obtained by four marker systems classified 40 genotypes in two groups with 0·45 genetic similarity with high Mantel matrix correlation (r=0·92). The principal component analysis (PCA) of marker data also explained 0·55 of the variation by first three components. Molecular diversity was very high and non-structured in these open-pollinated genotypes. The study demonstrated for the first time that URPs can be used successfully in genetic diversity analysis of tropical carrots. In addition, an entirely a new set of microsatellite markers, derived from the expressed sequence tags (ESTs) sequences of carrots, has been developed and utilized successfully.
An electron model with elementary charge
Authors: LEHNERT B. , HÖÖK L. J.
Published: January 2010

An earlier elaborated model of the electron, being based on a revised quantum electrodynamic theory, is further investigated in terms of an improved numerical iteration scheme. This point-charge-like model is based on the “infinity” of a divergent generating function being balanced by the “zero” of a shrinking characteristic radius. This eliminates the self-energy problem. According to the computations, the quantum conditions on spin, magnetic moment, and magnetic flux, plus the requirement of an elementary charge having the experimental value, can all be satisfied within rather narrow limits by a single scalar parameter. The revised model prevents the electron from “exploding” due to its eigencharge.
A new method of solution for one-dimensional quasi-neutral bounded plasmas
Authors: KAMRAN M. , KUHN S.
Published: January 2010

A new method is proposed for calculating the potential distribution Φ(z) in a one-dimensional quasi-neutral bounded plasma; Φ(z) is assumed to satisfy a quasi-neutrality condition (plasma equation) of the form ni{Φ(z)} = ne(Φ), where the electron density ne is a given function of Φ and the ion density ni is expressed in terms of trajectory integrals of the ion kinetic equation. While previous methods relied on formally solving a global integral equation (Riemann, Phys. Plasmas, vol. 13, 2006, paper no. 013503; Kos et al., Phys. Plasmas, vol. 16, 2009, paper no. 093503), the present method is characterized by piecewise analytic solution of the plasma equation in reasonably small intervals of z. As a first concrete application, Φ(z) is found analytically through order z4 near the center of a collisionless Tonks–Langmuir discharge with a cold-ion source.
Cubic polynomials with a parabolic point
Authors: ROESCH P.
Published: January 2010

We consider cubic polynomials with a simple parabolic fixed point of multiplier 1. For those maps, we prove that the boundary of the immediate basin of attraction of the parabolic point is a Jordan curve (except for the polynomial z+z3 where it consists in two Jordan curves). Moreover, we give a description of the dynamics and obtain the local connectivity of the Julia set under some assumptions.
Building back better? – negotiating normative boundaries of gender mainstreaming and post-tsunami reconstruction in Nanggroe Aceh Darussalam, Indonesia
Authors: JAUHOLA MARJAANA
Published: January 2010

This article focuses on gender mainstreaming policies and advocacy on gender equality in the post-tsunami context in Nanggroe Aceh Darussalam. Through the analysis, this article illustrates how gender mainstreaming policy documents and gender advocacy of the provincial and central government, when drawing from sex/gender division and binary of genders, reproduce heteronormative boundaries. By focusing on details, I argue that the image of the heteronormative nuclear family participates in normalising other identity categories; such as urban and middle-class. I also provide examples of how simultaneous to the production of dominant norms, gender advocacy challenges heteronormativity and norms governing heterosexuality and actively question the dominant gender norms. Drawing from postcolonial feminist and recent queer critiques, I argue that advocacy that solely focuses on gender and/or sexuality reduces human bodies and their desires to simplistic stick figures. Thus, it remains blind to other forms of violence, such as global economic and political frameworks that define ‘building back better’ primarily as recovery and rehabilitation of economy, assets and labour force.
Critical human security studies
Authors: NEWMAN EDWARD
Published: January 2010

From a critical security studies perspective – and non-traditional security studies more broadly – is the concept of human security something which should be taken seriously? Does human security have anything significant to offer security studies? Both human security and critical security studies challenge the state-centric orthodoxy of conventional international security, based upon military defence of territory against ‘external’ threats. Both also challenge neorealist scholarship, and involve broadening and deepening the security agenda. Yet critical security studies have not engaged substantively with human security as a distinct approach to non-traditional security. This article explores the relationship between human security and critical security studies and considers why human security arguments – which privilege the individual as the referent of security analysis and seek to directly influence policy in this regard – have not made a significant impact in critical security studies. The article suggests a number of ways in which critical and human security studies might engage. In particular, it suggests that human security scholarship must go beyond its (mostly) uncritical conceptual underpinnings if it is to make a lasting impact upon security studies, and this might be envisioned as Critical Human Security Studies (CHSS).
Systemic pressures and domestic ideas: a neoclassical realist model of grand strategy formation
Authors: KITCHEN NICHOLAS
Published: January 2010

Scholars in international relations have long known that ideas matter in matters of international politics, yet theories of the discipline have failed to capture their impact either in the making of foreign policy or the nature of the international system. Recent reengagement with the insights of classical realists has pointed to the possibility of a neoclassical realist approach that can take into account the impact of ideas. This article will suggest that the study of grand strategy can enlighten the intervening ideational variables between the distribution of power in the international system and the foreign policy behaviour of states, and thus constitute the key element in a neoclassical realist research agenda.
The torture convention, rendition and Kant's critique of ‘pseudo-politics’
Authors: WILLIAMS HOWARD
Published: January 2010

By what standards ought we to judge politicians? The article addresses the question in the light of the treatment of two controversial issues in contemporary world politics: the implementation of the 1984 UN Convention against Torture; and the post 9/11 rendition of terrorist suspects to US authorities by European governments. Their treatment brings out the way in which the role of political leaders is popularly conceived and understood. This conventional understanding is contrasted with the role recommended by Kant's political philosophy. An answer to the question depends on how we conceive politics in the first place. If politics is seen as a ‘free for all’ where all strategies can be canvassed then the response will be entirely different from a situation where we consider ourselves bound by rules of legitimacy and its attendant problems of morality and law. The article represents a rejection of certain received accounts of politics and approval of a Kantian view. The account of politics which in one respect or another tries to drive a wedge between politics and ordinary morality is seen as inferior to a Kantian concept of politics which is always conditioned by morality.
Dying for the state: the missing just war question?
Authors: BARON ILAN ZVI
Published: January 2010

This article introduces the problem of having to risk one's life for the state in war, asking first why this question is no longer asked in the just war literature and then suggesting five issues that relate to this question: 1) that of individual consent, 2) whether or not any state can be justified in obliging its citizens in this regard and whether or not the type of government is important, 3) whether or not the problem of the obligation differs between conscript and volunteer armies, 4) the problem of political obligation and how any individual could be justifiably obliged to risk his or her life for the state in war, and 5) the question of whether a citizen may be obliged to go into any war. The argument is that these questions are no longer given much attention in the just war literature because of the way that the concept of proper authority has come to be understood. The article concludes by suggesting that the problem of the ‘obligation to die’ should be included in our understanding and use of just war theory and the ethics of war.
A comparison of risk factors associated with community-associated methicillin-resistant and -susceptibleStaphylococcus aureusinfections in remote communities
Authors: GOLDING G. R. , LEVETT P. N. , McDONALD R. R. , IRVINE J. , NSUNGU M. , WOODS S. , HORBAL A. , SIEMENS C. G. , KHAN M. , OFNER-AGOSTINI M. , MULVEY M. R. ,   the Northern Antibiotic Resistance Partnership (NARP)
Published: January 2010

In this case-control study, cases [community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA),n=79] and controls [community-associated methicillin-susceptibleS. aureus(CA-MSSA),n=36] were defined as a laboratory-confirmed infection in a patient with no previous hospital-associated factors. Skin and soft tissue were the predominant sites of infection, both for cases (67·1%) and controls (55·6%). Most of the cases (79·7%) and controls (77·8%) were aged <30 years. Investigations did not reveal any significant statistical differences in acquiring a CA-MRSA or CA-MSSA infection. The most common shared risk factors included overcrowding, previous antibiotic usage, existing skin conditions, household exposure to someone with a skin condition, scratches/insect bites, and exposure to healthcare workers. Similar risk factors, identified for both CA-MRSA and CA-MSSA infections, suggest standard hygienic measures and proper treatment guidelines would be beneficial in controlling both CA-MRSA and CA-MSSA in remote communities.
Spatial analysis of melioidosis distribution in a suburban area
Authors: CORKERON M. L. , NORTON R. , NELSON P. N.
Published: January 2010

Burkholderia pseudomallei, the causative agent of melioidosis is associated with soil. This study used a geographic information system (GIS) to determine the spatial distribution of clinical cases of melioidosis in the endemic suburban region of Townsville in Australia. A total of 65 cases over the period 1996–2008 were plotted using residential address. Two distinct groupings were found. One was around the base of a hill in the city centre and the other followed the old course of a major waterway in the region. Both groups (accounting for 43 of the 65 cases examined) are in areas expected to have particularly wet topsoils following intense rainfall, due to soil type or landscape position.
Disease transmission model for community-associated Clostridium difficile infection
Authors: OTTEN A. M. , REID-SMITH R. J. , FAZIL A. , WEESE J. S.
Published: January 2010

Participating researchers and public health personnel at a Canadian workshop in 2007, noted considerable gaps in current understanding of community-associated Clostridium difficile infection (CA-CDI), specifically infection sources and risk factors. A disease transmission model for CA-CDI was requested as an initial step towards a risk assessment, to analyse infection sources and risk factors, addressing priority research areas. The developed model contains eight infection states (susceptible, gastrointestinal exposure, colonized, diseased, deceased, clinically resolved colonized, relapse diseased, and cleared) and notes directional transfers between the states. Most published research used focused on hospital-associated C. difficile infection (HA-CDI) and further studies are needed to substantiate the use of HA-CDI knowledge in the transmission of CA-CDI. The aim was to provide a consistent framework for researchers, and provide a theoretical basis for future quantitative risk assessment of CA-CDI.
Face masks to prevent transmission of influenza virus: a systematic review
Authors: COWLING B. J. , ZHOU Y. , IP D. K. M. , LEUNG G. M. , AIELLO A. E.
Published: January 2010

Influenza viruses circulate around the world every year. From time to time new strains emerge and cause global pandemics. Many national and international health agencies recommended the use of face masks during the 2009 influenza A (H1N1) pandemic. We reviewed the English-language literature on this subject to inform public health preparedness. There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Further studies in controlled settings and studies of natural infections in healthcare and community settings are required to better define the effectiveness of face masks and respirators in preventing influenza virus transmission.
Mixed viral infections causing acute gastroenteritis in children in a waterborne outbreak
Authors: RÄSÄNEN S. , LAPPALAINEN S. , KAIKKONEN S. , HÄMÄLÄINEN M. , SALMINEN M. , VESIKARI T.
Published: January 2010

We examined stool specimens for viral pathogens from 50 children referred to hospital due to acute gastroenteritis (AGE) resulting from consuming drinking water contaminated with sewage in a Finnish community using PCR methods. Rotavirus was detected in 33 (66%), human calicivirus in 31 (62%), and both in 40% of cases. Of the caliciviruses, 20/31 (65%) were noroviruses and 11 (35%) sapoviruses. Furthermore, Aichi virus was detected in 25 (50%), adenovirus in six (12%) and bocavirus in four (8%) cases.Campylobacter jejuniwas present in 20 (61%) andSalmonellain four (12%) of the 33 stools cultured for bacteria. On a 20-point scale median severity score of AGE in the 28 hospitalized children was 17; the severity was similar regardless of viruses detected. Bloody diarrhoea occurred only whenC. jejuniwas present. To conclude, massive exposure to several AGE viruses caused mixed infections and severe AGE regardless of the aetiological agents.
First articulated skeleton of Palaeeudyptes gunnari from the late Eocene of Isla Marambio (Seymour Island), Antarctica
Authors: Hospitaleche Carolina Acosta , Reguero Marcelo
Published: January 2010

The first articulated skeleton of a penguin from the late Eocene of Antarctica is described. MLP 96-I-6-13 comes from the upper Submeseta Allomember (La Meseta Formation) of Isla Marambio (locality DPV 10/84). The significance of this finding in the context of the Anthropornis nordenskjoeldi biozone is discussed. An osteologic description of the recovered elements and a brief discussion of its systematic determination are provided. MLP 96-I-6-13 is the first articulated skeleton with sure specific assignment to Palaeeudyptes gunnari (Wiman, 1905), a species previously known only through isolated tarsometatarsi and included in the groups of Wiman.
Spatial distribution, habitat preference and colonization status of two alien terrestrial invertebrate species in Antarctica
Authors: Hughes Kevin A. , Worland M. Roger
Published: January 2010

The introduction of invasive species is one of the greatest threats to Earth’s biodiversity, as they can reduce native biodiversity and alter ecosystem structure and function. Currently, the only two known non-native terrestrial invertebrates in Antarctica are the chironomid midge Eretmoptera murphyi and the enchytraeid worm Christensenidrilus blocki. These invertebrates were probably introduced to ground near Signy Research Station, South Orkney Islands, during transplantation experiments in the late 1960s. Between 2007 and 2009, this study surveyed the area around the introduction site for midge larvae and worms to assess any change over the last four decades in their spatial distribution, habitat preference and colonization status. Eretmoptera murphyi was found in concentrations up to 4.1 × 105 larvae m-2 (mean 2.1 × 104 larvae m-2) at distances of up to 220 m from the probable introduction site (c. 35 000 m2), while C. blocki was only found close to the introduction site in low numbers. Significantly more E. murphyi larvae were found in peat and dead organic material (3.34 × 104 m-2) than in stony soil and gravel (1.52 × 104 m-2) or living moss and other plant material (1.16 × 104 m-2). Eretmoptera murphyi can no longer be considered a persistent alien as it clearly expanding its distribution, while C. blocki remains a persistent alien species.
On the Subtree Size Profile of Binary Search trees
Authors: DENNERT FLORIAN , GRÜBEL RUDOLF
Published: January 2010

For random trees T generated by the binary search tree algorithm from uniformly distributed input we consider the subtree size profile, which maps k ∈ ℕ to the number of nodes in T that root a subtree of size k. Complementing earlier work by Devroye, by Feng, Mahmoud and Panholzer, and by Fuchs, we obtain results for the range of small k-values and the range of k-values proportional to the size n of T. In both cases emphasis is on the process view, i.e., the joint distributions for several k-values. We also show that the dynamics of the tree sequence lead to a qualitative difference between the asymptotic behaviour of the lower and the upper end of the profile.
UNIVALENT HARMONIC MAPPINGS INTO TWO-SLIT DOMAINS
Authors: GANCZAR ANDRZEJ , WIDOMSKI JAROSŁAW
Published: January 2010

We study some classes of planar harmonic mappings produced with theshear constructiondevised by Clunie and Sheil-Small in 1984. The first section reviews the basic concepts and describes the shear construction. The main body of the paper deals with the geometry of the classes constructed.
Interactions of host APOBEC3 restriction factors with HIV-1 in vivo: implications for therapeutics
Authors: Albin John S. , Harris Reuben S.
Published: January 2010

Restriction factors are natural cellular proteins that defend individual cells from viral infection. These factors include the APOBEC3 family of DNA cytidine deaminases, which restrict the infectivity of HIV-1 by hypermutating viral cDNA and inhibiting reverse transcription and integration. HIV-1 thwarts this restriction activity through its accessory protein virion infectivity factor (Vif), which uses multiple mechanisms to prevent APOBEC3 proteins such as APOBEC3G and APOBEC3F from entering viral particles. Here, we review the basic biology of the interactions between human APOBEC3 proteins and HIV-1 Vif. We also summarise, for the first time, current clinical data on the in vivo effects of APOBEC3 proteins, and survey strategies and progress towards developing therapeutics aimed at the APOBEC3–Vif axis.
THE MODAL LOGIC OF STONE SPACES: DIAMOND AS DERIVATIVE
Authors: BEZHANISHVILI GURAM , ESAKIA LEO , GABELAIA DAVID
Published: January 2010

We show that if we interpret modal diamond as the derived set operator of a topological space, then the modal logic of Stone spaces isK4and the modal logic of weakly scattered Stone spaces isK4G. As a corollary, we obtain thatK4is also the modal logic of compact Hausdorff spaces andK4Gis the modal logic of weakly scattered compact Hausdorff spaces.
Initial expansion of the Columbia River tidal plume: Theory and remote sensing observations
Authors: Jay David A. , Zaron Edward D. , Pan Jiayi
Published: January 2010

Analysis of the Columbia River tidal plume using Lagrangian frontal equations provides a concise description of the evolution of frontal depth H, velocity U, reduced gravity g′, and frontal internal Froude number FR. Because the estuary mouth is narrow, the initial radial plume motion is supercritical (FR > 1) for up to 12 hours. Understanding this supercritical phase is vital, because plume properties change rapidly, with strong ecosystem impacts. To analyze this expansion, analytical and numerical models (the latter with three mixing formulations) were tested. Model results are compared to synthetic aperture radar images to verify that the predicted frontal properties are realistic. Lagrangian theory provides especially simple constraints (independent of the mixing model) on spatial variations in FR and Ug′H. For parameters representative of the Columbia River plume, the plume spreads 10–35 km and thins to 25–60% of its initial depth before becoming subcritical. After liftoff, FR increases as the front accelerates and thins, it then decreases to unity; g′ decreases, but more slowly than H and U. H, controlled by a balance between spreading and mixing, first decreases then increases. The strength of vertical mixing and the mixing efficiency EF (ratio of buoyancy flux to dissipation) both play a significant role in determining plume properties, and it is important to include both the horizontal gradient in g′ and surface slope component of the pressure gradient. A model with an Ellison‐Turner type entrainment scheme predicts the plume trajectory better than one that assumes a constant interfacial gradient Richardson number.
Interaction of multiple magnetic islands in a long current sheet: Two‐fluid simulations
Authors: Nakamura T. K. M. , Fujimoto M. , Sekiya H.
Published: January 2010

We have studied the magnetic island coalescence process in an open system with two‐fluid simulations including electron inertial effects. We have found that the two X‐lines at the lateral‐edges of a perturbed current sheet possess the intrinsic advantage to dominate and to create an inflating magnetic island between them. While this state will eventually be taken over by the well‐known single X‐line structure, the double X‐line state can be extended in time and is expected commonly in maturing stages of reconnection regions.
Deflection and enhancement of solar energy particle flux at the Moon by structures within the terrestrial magnetosphere
Authors: Harnett E. M.
Published: January 2010

The Moon spends 25% of its orbit within the terrestrial magnetosphere. Particle tracking is used to investigate access points of 35 MeV and 760 MeV particles into the magnetosphere for both quiet and disturbed magnetospheric conditions. The results indicate that solar energetic particle (SEP) flux at the Moon can be reduced for storm conditions when the magnitude of the magnetic field in the sheath is enhanced, as particles in the 35 MeV range have limited access to the magnetosphere for storm conditions. Plasmoids are also effective at reducing SEP flux from the tailward direction. The results also indicate that the flux of SEPs from the dawnside of the magnetosphere can be focused into the current sheet, leading to a potential enhancement in SEP flux at the Moon. Particles traveling up the tail for both quiet and storm conditions tended to experience the greatest deflection away from the central tail.
Plasma sheet pressure evolution related to substorms
Authors: Xing X. , Lyons L. R. , Angelopoulos V. , Larson D. , Carlson C. , Runov A. , Auster U.
Published: January 2010

We have investigated the inner equatorial plasma sheet plasma pressure evolution associated with substorm onsets using the five THEMIS spacecraft data during the 2008 tail season. The central plasma sheet thermal pressure is estimated from the thermal and magnetic pressure based on one dimensional pressure balance. The results show that for a majority of substorm cases, the plasma pressure enhances after onset earthward of ∼12 RE radial distance. On the other hand, the plasma pressure beyond ∼16 RE shows a remarkable decrease near onset. During the recovery phase, the pressure gradually returns to its original level. These results indicate that during the substorm expansion phase, the current wedge usually expands to the region tailward of ∼16 RE with the inner edge earthward of this radial distance. The pressure increase earthward of ∼12 RE could be associated with an increase of cross‐tail current, though this is not necessarily so due to the nontail‐like magnetic field geometry after dipolarization. For a minority of cases, the pressure fluctuates without net change or reduces at ∼11 RE. During these events, the ground magnetic perturbations and the estimated center of the westward electrojet extend further equatorward than for the pressure increase cases. There is also evidence that aurora breakup occurs further equatorward when there is a pressure reduction, indicating a more earthward penetration of the plasma sheet. During these cases, the current wedge represented by pressure reduction is clearly observed earthward to ∼11 RE. The relationship between the auroral break up arc, which is believed to map to ∼10 RE, and may be associated with a precursor pressure enhancement, and the inner plasma sheet pressure and current evolution near onset warrants more careful analysis.
A systematically coarse-grained model for DNA and its predictions for persistence length, stacking, twist, and chirality
Authors: Morriss-Andrews Alex , Rottler Joerg , Plotkin Steven S.
Published: January 2010

We introduce a coarse-grained model of DNA with bases modeled as rigid-body ellipsoids to capture their anisotropic stereochemistry. Interaction potentials are all physicochemical and generated from all-atom simulation/parameterization with minimal phenomenology. Persistence length, degree of stacking, and twist are studied by molecular dynamics simulation as functions of temperature, salt concentration, sequence, interaction potential strength, and local position along the chain for both single- and double-stranded DNA where appropriate. The model of DNA shows several phase transitions and crossover regimes in addition to dehybridization, including unstacking, untwisting, and collapse, which affect mechanical properties such as rigidity and persistence length. The model also exhibits chirality with a stable right-handed and metastable left-handed helix.
Optical waveguide simulations for the optimization of InGaN-based green laser diodes
Authors: Huang Chia-Yen , Lin You-Da , Tyagi Anurag , Chakraborty Arpan , Ohta Hiroaki , Speck James S. , DenBaars Steven P. , Nakamura Shuji
Published: January 2010

Two-dimensional optical waveguide mode simulations have been employed to investigate the optimized device structures for ridge-waveguide (Al, In, Ga) N-based green (520nm) laser diodes (LDs). The effects of thicknesses, alloy compositions, and doping densities of each epitaxially grown layers as well as ridge geometries on optical confinement factors (Γ) and waveguide absorption (α) were comprehensively surveyed. InyGa1−yN (y=0.07–0.1) guiding layers (GLs) with thickness more than 50nm were effective for realizing high Γ and low α. To minimize the absorption by the anode metal, p-cladding layer (p-CL) was required to be more than 500nm. At the same time, low index insulator such as SiO2 was preferable for the narrow ridge, where the thickness at the sidewall had to be more than 60nm. We also found that InGaN barriers layers between the quantum wells (QWs) were superior to GaN barriers to increase Γ and reduce α. Moreover, a thicker last barrier between the topmost QW and the electron blocking layer was also effective to reduce α. Regarding the effect of Mg doping concentration on the absorption, the reduction in Mg in the p-CL and the p-GL was significant to reduce α. Generally, it was confirmed the design for typical 405nm LDs can be applied for 520nm LD with the inclusion of InGaN GLs and barriers for the QWs.
Simulations and model of the nonlinear Richtmyer–Meshkov instability
Authors: Dimonte Guy , Ramaprabhu P.
Published: January 2010

The nonlinear evolution of the Richtmyer–Meshkov (RM) instability is investigated using numerical simulations with the FLASH code in two dimensions. The purpose of the simulations is to develop an empirical nonlinear model of the RM instability that is applicable to inertial confinement fusion (ICF) and ejecta formation, namely, at large Atwood number A and scaled initial amplitude kho (k≡wave number) of the perturbation. The FLASH code is first validated with a variety of RM experiments that evolve well into the nonlinear regime. They reveal that bubbles stagnate when they grow by an increment of 2/k and that spikes accelerate for A>0.5 due to higher harmonics that focus them. These results are then compared with a variety of nonlinear models that are based on potential flow. We find that the models agree with simulations for moderate values of A<0.9 and kho<1, but not for the larger values that characterize ICF and ejecta formation. We thus develop a new nonlinear empirical model that captures the simulation results consistent with potential flow for a broader range of A and kho. Our hope is that such empirical models concisely capture the RM simulations and inspire more rigorous solutions.
Initial stages of Mg adsorption on the Si(111)-7×7 surface
Authors: Chen Xiaohang , Zhan Huahan , Zhou Changjie , Chen Bo , Kang Junyong
Published: January 2010

First-principles calculations are performed to determine the configurations of adsorbed Mg atoms on the Si(111)-7×7 surface. It is shown that Mg atoms prefer to occupy the higher coordination sites of the faulted half unit cell and that they may diffuse laterally to the nearby ones around the same Si center adatom by overcoming a low diffusion barrier of 0.1325 eV. These characteristics are attributed to weak interactions among Mg and nearby Si atoms. The initial adsorption processes of Mg atoms on the Si(111)-7×7 surface are investigated by scanning tunneling microscopy imaging at room temperature. Three types of adsorption sites are identified, which, by comparing with theoretical simulations, are found to be associated with the adsorbed configurations of one, two, and three Mg atoms, respectively.
Ferroelectric and electromechanical property characterization of single Pb(ZrTi)O3 fiber resonator
Authors: Sun Chengliang , Qin Lifeng , Xue Hao , Xiong Zhaoxian , Wang Qing-Ming
Published: January 2010

Piezoelectric fibers and fiber composites have attracted much attention for anisotropic sensing and actuation applications in recent year. Complete property characterization for piezoelectric fibers is essential for material and device design and fabrication. In this work, ferroelectric and electromechanical properties of single piezoelectric Pb(ZrTi)O3 (PZT) fiber were characterized by polarization–electric field hysteresis loop measurement using single PZT fiber/polymer 1–3 composite approach, and by direct measurement of the complex impedance spectrum of single PZT fiber resonator. A normalized electrical impedance spectrum method developed recently was used to determine the complex piezoelectric, elastic, and dielectric coefficients, mechanical quality factor and electromechanical coefficient from the complex electrical impedance-frequency spectrum measurement. The results were compared with those determined by the IEEE standard method for the pure length extensional resonator. The permittivity of PZT fiber was found larger than PZT bulk materials, which was attributed for the core-shell structure of the fibers.
Assignment of phantom bands in the solid-state infrared and Raman spectra of coronene: The importance of a minute out-of-plane distortion
Authors: Todorov Petar D. , Jenneskens Leonardus W. , van Lenthe Joop H.
Published: January 2010

The molecular geometry and the normal modes properties of coronene are investigated by means of DFT(B3LYP) and restricted/Hartree–Fock calculations utilizing basis sets of triple zeta+polarization quality. The interpretation of the infrared and Raman spectra of coronene, especially in solid state, is critically revised. The phantom bands in the solid state, previously not understood, are readily assigned after considering a minute out-of-plane molecular distortion from D6h to C2h.
Synthesis of crystalline Si quantum dots by millisecond laser irradiation of SiOxNy layers
Authors: Mannino Giovanni , Spinella Corrado , Bongiorno Corrado , Nicotra Giuseppe , Mercorillo Flora , Privitera Vittorio , Franzò Giorgia , Piro Alberto Maria , Grimaldi MariaGrazia , Di Stefano Maria Ausilia , Di Marco Silvestra
Published: January 2010

We demonstrated that the timescale for Si quantum dot (Si-QD) formation in a SiOxNy layer is a few milliseconds by IR laser irradiation. The amount of Si agglomerated into QD in a laser irradiated SiOxNy layer is comparable to that calculated after furnace annealing at 1250 °C for 30 min. However, we found that crystalline Si-QD can be formed by laser only if the amount of Si atoms in excess is as high as 1×1022/cm3. The Si-QD contains impurities like N and O that prevent luminescence at 900 nm. The photoluminescence (PL) signal is recorded only after an additional annealing after laser irradiation at temperatures above 1000 °C when diffusion-assisted replacement of N and O occurs.
Spatiotemporal correlations in denatured proteins: The dependence of fluorescence resonance energy transfer (FRET)-derived protein reconfiguration times on the location of the FRET probes
Authors: Makarov Dmitrii E.
Published: January 2010

There has been considerable effort to understand the inherent time scale for conformational reconfiguration of denatured proteins. Even a simple homopolymer, however, exhibits a spectrum of fluctuation time scales rather than a unique characteristic time. Consequently, different time scales may be probed by different measurements. Motivated by recent single-molecule fluorescence resonance energy transfer experiments, here I have studied theoretically how the characteristic time scale exhibited by fluctuations of the distance between two residues within an unfolded polypeptide depends on the choice of the residue pair. This time scale was generally found to become shorter as the sequence separation between the residues is reduced. The maximum reconfiguration time, however, corresponds not to the residues being located at the ends of the chain but rather to each residue residing a short length apart from the ends. Comparison of these findings with recent single-molecule measurements suggests that the latter may bear signatures of transient residual structure.
Ultrafast relaxation and 2D IR of the aqueous trifluorocarboxylate ion
Authors: Kuroda Daniel G. , Vorobyev Dmitriy Yu. , Hochstrasser Robin M.
Published: January 2010

The asymmetric stretching vibration of the amphiphilic trifluoroacetate ion and its C13O16 isotopologue in D2O were investigated with infrared spectroscopy (FTIR), ultrafast infrared pump probe, and two dimensional vibrational photon echo techniques and simulations. Trifluoroacetate ions have a nonexponential depopulation of the first vibrational excited state, which is well described by a kinetic mechanism involving a temperature dependent solvent assisted relaxation to the symmetric stretch mode. The vibrational spectrum of the asymmetric stretch of the C13O16 isotopologue presents an unusual spectral shape. The frequency-frequency autocorrelation function shows a static term not present in the C13O16 form, which is caused by an accidental degeneracy with a combinational mode. A newly developed frequency map for carboxylate is used to characterize the processes and dynamics observed in the frequency fluctuations of the carboxylate asymmetric stretch mode in aqueous solution. An assignment of the molecular processes that govern the frequency fluctuations is suggested from an analysis of the solvation shell configurations obtained from molecular dynamics simulations.
Benchmark all-electron ab initio quantum Monte Carlo calculations for small molecules
Authors: Nemec Norbert , Towler Michael D. , Needs R. J.
Published: January 2010

We study the efficiency, precision and accuracy of all-electron variational and diffusion quantum Monte Carlo calculations using Slater basis sets. Starting from wave functions generated by Hartree–Fock and density functional theory, we describe an algorithm to enforce the electron-nucleus cusp condition by linear projection. For the 55 molecules in the G2 set, the diffusion quantum Monte Carlo calculations recovers an average of 95% of the correlation energy and reproduces bond energies to a mean absolute deviation of 3.2 kcal/mol. Comparing the individual total energies with essentially exact values, we investigate the error cancellation in atomization and chemical reaction path energies, giving additional insight into the sizes of nodal surface errors.
Time-resolved x-ray scattering from laser-molten indium antimonide
Authors: Nüske R. , v. Korff Schmising C. , Jurgilaitis A. , Enquist H. , Navirian H. , Sondhauss P. , Larsson J.
Published: January 2010

We demonstrate a concept to study transient liquids with picosecond time-resolved x-ray scattering in a high-repetition-rate configuration. Femtosecond laser excitation of crystalline indium antimonide (InSb) induces ultrafast melting, which leads to a loss of the long-range order. The remaining local correlations of the liquid result in broad x-ray diffraction rings, which are measured as a function of delay time. After 2 ns the liquid structure factor shows close agreement with that of equilibrated liquid InSb. The measured decay of the liquid scattering intensity corresponds to the resolidification rate of 1 m/s in InSb.
Note: Investigation of a null measurement of optical absorbance using a pulse width modulated light-emitting diode
Authors: Rusak David A. , Kawka Ernest A. , Trexler E. Brady
Published: January 2010

We examined the possibility of making a null measurement of optical absorbance by using pulse-width modulation to control the intensity of a light-emitting diode (LED). This type of measurement is intriguing because the instrumental sources of noise are different from those in the traditional absorbance measurement. Our experiment employed phototransistor detectors and a RC integrator to measure the amount of light being transmitted. However, instead of measuring the ratio of the detector voltages for a blank and sample, we measured the ratio of the LED duty cycles required to give the same detector voltage for a blank and a sample. Using this method, it is presumed that  the same amount of light reaches the detector during measurement of the blank and sample.
Experiments on rotamak plasma equilibrium and shape control
Authors: Petrov Yuri , Yang Xiaokang , Wang Yonghui , Huang Tian-Sen
Published: January 2010

A set of magnetic shaping coils and copper rings is installed in cylindrical chamber rotamak to allow for an active equilibrium control in 40 ms plasma discharges. The coils, which are powered by programmable current source, are used to control both the plasma shape and the boundary poloidal magnetic flux. Without the active equilibrium control, the boundary flux drops from its vacuum value of 0.3 mWb to zero after the plasma current is generated. If the coils are activated, the boundary magnetic flux can be sustained within the 0.2–0.3 mWb range, thus keeping the separatrix away from chamber wall during whole period of the shot. The passive copper rings help in eliminating the fast variations of the boundary magnetic flux. The response of rotamak plasma to the active equilibrium control is drastically different in regimes with or without external toroidal field. A model is presented that describes the change in plasma shape, plasma current, and pressure under the effect of active equilibrium coils.
Correlation energy functional and potential from time-dependent exact-exchange theory
Authors: Hellgren Maria , von Barth Ulf
Published: January 2010

In this work we studied a new functional for the correlation energy obtained from the exact-exchange (EXX) approximation within time-dependent density functional theory. Correlation energies have been calculated for a number of different atoms showing excellent agreement with results from more sophisticated methods. These results lose little accuracy by approximating the EXX kernel by its static value, a procedure which enormously simplifies the calculations. The correlation potential, obtained by taking the functional derivative with respect to the density, turns out to be remarkably accurate for all atoms studied. This potential has been used to calculate ionization potentials, static polarizabilities, and van der Waals coefficients with results in close agreement with experiment.
AlGaN/GaN high electron mobility transistors as a voltage-tunable room temperature terahertz sources
Authors: El Fatimy A. , Dyakonova N. , Meziani Y. , Otsuji T. , Knap W. , Vandenbrouk S. , Madjour K. , Théron D. , Gaquiere C. , Poisson M. A. , Delage S. , Prystawko P. , Skierbiszewski C.
Published: January 2010

We report on room temperature terahertz generation by a submicron size AlGaN/GaN-based high electron mobility transistors. The emission peak is found to be tunable by the gate voltage between 0.75 and 2.1 THz. Radiation frequencies correspond to the lowest fundamental plasma mode in the gated region of the transistor channel. Emission appears at a certain drain bias in a thresholdlike manner. Observed emission is interpreted as a result of Dyakonov–Shur plasma wave instability in the gated two-dimensional electron gas.
Contrast inversion of the apparent barrier height of Pb thin films in scanning tunneling microscopy
Authors: Becker Michael , Berndt Richard
Published: January 2010

Scanning tunneling microscopy measurements of the apparent height of the tunneling barrier are analyzed for Pb islands on Ag(111). The apparent barrier height (ABH) significantly varies with the bias voltage. This bias dependence leads to drastic changes and even inversion of contrast in spatial maps of the ABH. Using model calculations, these variations are interpreted in terms of the strongly modulated local density of states of thin Pb films, which is caused by quantum well states.