bluuebunny/crossref_metadata_2025 huggingface dataset:
A cost-effectiveness study of the community-based intervention ‘10 000 Steps Ghent’
Authors: De Smedt Delphine , De Cocker Katrien , Annemans Lieven , De Bourdeaudhuij Ilse , Cardon Greet
Published: August 2011

Objective

To evaluate the cost-effectiveness of the European community-based project ‘10 000 Steps Ghent’, an intervention that resulted in a significant decrease in sedentary time and a significant increase in step counts (896 steps/d) and self-reported walking (66 min/week).

Design

An age- and gender-dependent Markov model, with a time horizon of 20 years and a cycle length of 1 year, estimating the development of diabetes, cardiovascular events and colorectal cancer.

Setting

All individuals started in a health state free of events. The effect of the intervention was based on published risk reductions related to increased walking time. Costs and utility decrements related to events were obtained from published literature. The impact of the uncertainty of the parameters on incremental costs and quality-adjusted life years (QALY) were assessed with one-way sensitivity analyses and a Monte Carlo analysis.

Subjects

Cohort representing the population reached by the intervention (266 adults aged 25–75 years with a mean age of 48·2 (sd13·1) years, 45·6 % men, 64·6 % highly educated, 70·0 % employed).

Results

Implementing the community-based programme increased average QALY by 0·16 and 0·11 for men and women, respectively. The total costs decreased by approximately 576€ and 427€, respectively. Hence, for both genders the intervention programme was dominant. The sensitivity analyses did not change the conclusion of dominance.

Conclusion

The community-based ‘10 000 Steps Ghent’ campaign is a dominant intervention. Sensitivity analyses have proved the robustness of the results; hence implementing this intervention on a population-based level could lead to improved health outcomes and reduced costs.
Impact of awareness of the Japanese Food Guide Spinning Top on eating behaviour
Authors: Takaizumi Kanae , Harada Kazuhiro , Shibata Ai , Nakamura Yoshio
Published: August 2011

Objective

To investigate whether awareness of the Japanese Food Guide (JFG) can promote changes in eating behaviour.

Design

A longitudinal study was conducted in 2007 and 2009 by means of an Internet-based survey. Awareness status of the JFG and a sixteen-item scale for calculating eating behaviour scores were obtained.

Setting

Japan.

Subjects

In total, 787 Japanese adults (20–59 years) who registered with an Internet research service organization were included in the study. The respondents were divided into three groups. The respondents who were aware of the JFG in 2007 were categorized into Group 1. Those who were not aware of the JFG in 2007 were categorized into either Group 2 or Group 3. Group 2 became aware of the JFG by 2009, and Group 3 was not aware of the JFG in 2009.

Results

In Group 2, the eating behaviour score increased significantly by 0·8 points from 4·7 in 2007 to 5·5 in 2009 (P = 0·004). The eating behaviour score of Group 1 (6·5 points in 2007; 6·3 points in 2009) and Group 3 (3·8 points in 2007; 4·1 points in 2009) did not change significantly from 2007 to 2009.

Conclusions

Awareness of the JFG promoted eating behaviour change in the Japanese population. The results indicate that awareness of nutrition information from sources such as the JFG would promote healthy eating.
Exploring school and home food environments: perceptions of 8–10-year-olds and their parents in Newcastle upon Tyne, UK
Authors: Briggs Laura , Lake Amelia A
Published: August 2011

Objective

To use an innovative mixed-method approach to analyse and describe 8–10-year-olds’ home and school food environments.

Design

A mixed-method approach to collect qualitative and quantitative data was used, in which pupils took photographs over four days to record their food intake and food environment. The photographs were discussed in focus groups. A combination of lunchtime observations and questionnaires completed by parents were used to build up a picture of the children's home and school food environments.

Setting

A primary school in a suburb of Newcastle upon Tyne, UK.

Subjects

Twenty-seven children aged 8–10 years consented to take part in the study. Twenty-four returned cameras, and eighteen parents completed questionnaires.

Results

Photographs illustrated a range of locations throughout the home where children consumed food. Children's photographs revealed they ate less often with family and more often in front of the television than reported in parental questionnaires. Emergent themes during focus group discussions revealed a strong preference for packed lunches and dissatisfaction with school dinners. In this small sample, children's eating habits and preferences showed few associations with either gender or the deprivation level of the area in which they lived.

Conclusions

The children's home food environments showed a great deal of variation, with parents being key moderators of food availability and consumption. While the school's food provisions met national nutritional standards, the social aspects of having a packed lunch appeared to be a positive aspect of eating at school.
Positive impact of a pre-school-based nutritional intervention on children's fruit and vegetable intake: results of a cluster-randomized trial
Authors: De Bock Freia , Breitenstein Luise , Fischer Joachim E
Published: August 2011

Objective

To assess the short-term impact of a nutritional intervention aimed at reducing childhood overweight in German pre-school children.

Design

Using a cluster-randomized study design with waiting-list controls, we tested a 6-month intervention administered once weekly by a nutrition expert consisting of joint meal preparation and activities for children and parents such as tasting and preparing nutritious, fresh foods. At baseline, 6 and 12 months, a parent-completed questionnaire assessed fruit and vegetable intakes (primary outcomes) and water and sugared drinks consumption (secondary outcomes). Direct measurement assessed BMI, skinfold thickness and waist-to-height-ratio. An intention-to-treat analysis used random-effects panel regression models to assess the intervention effect, adjusted for each child's age, gender, immigrant background and maternal education.

Setting

Eighteen pre-schools from three south German regions.

Subjects

Healthy children aged 3–6 years.

Results

Three hundred and seventy-seven (80 %) eligible pre-school children participated in the study. Of these, 348 provided sufficient data for analysis. The sample mean age was 4·26 (sd0·78) years; the majority (53·2 %) were boys. Children's fruit and vegetable intakes increased significantly (P< 0·001 andP< 0·05, respectively); no significant changes in the consumption of water, sugared drinks or anthropometric measurements were noted.

Conclusions

Nutritional interventions in pre-schools have the potential to change eating behaviours in young children, which in the long term might reduce risk for developing overweight.
Prolonged breast-feeding protects mothers from later-life obesity and related cardio-metabolic disorders
Authors: Wiklund Petri , Xu Leiting , Lyytikäinen Arja , Saltevo Juha , Wang Qin , Völgyi Eszter , Munukka Eveliina , Cheng Shumei , Alen Markku , Keinänen-Kiukaanniemi Sirkka , Cheng Sulin
Published: August 2011

Objective

To investigate the long-term effects of duration of postpartum lactation on maternal body composition and risk for cardio-metabolic disorders in later life.

Design

Retrospective study. Body composition was measured using dual-energy X-ray absorptiometry and serum glucose, insulin and lipids were analysed using enzymatic photometric methods 16–20 years after the last pregnancy. Medical history and lifestyle factors were collected via a self-administered questionnaire. Detailed information regarding weight change patterns during each pregnancy was obtained from personal maternity tracking records.

Setting

City of Jyväskylä and surroundings in Central Finland.

Subjects

Two hundred and twelve women (mean age 48, range 36–60 years).

Results

At 16–20 years after their last pregnancy, women who had breast-fed for less than 6 months had higher total body fat mass and fat mass percentage, particularly in the android region (46·5 (sd8·2) %) than mothers who had breast-fed for longer than 6 months (39·0 (sd10·2) %) or for longer than 10 months (38·4 (sd10·9) %,P< 0·01). These differences were independent of pre-pregnancy weight and BMI, menopausal status, smoking status, level of education, participation in past and present leisure-time physical activity, and current dietary energy intake. Higher body fat mass was also associated with higher fasting serum glucose concentration and insulin resistance, TAG, LDL cholesterol and total cholesterol concentrations, as well as higher systolic and diastolic blood pressure (P< 0·05 for all).

Conclusions

Short duration of breast-feeding may induce weight retention and fat mass accumulation, resulting in increased risk of cardio-metabolic disorders in later life.
Urban v. suburban perceptions of the neighbourhood food environment as correlates of adolescent food purchasing
Authors: Hearst Mary O , Pasch Keryn E , Laska Melissa N
Published: August 2011

Objective

To assess the relationship between adolescent perception of time to walk to neighbourhood food retail outlets and purchasing of sugar-sweetened beverages (SSB), fast and convenience food items, and to test for differences by urban v. suburban environment.

Design

Cross-sectional observational study.

Setting

Twin Cities Metropolitan Area, Minnesota, USA.

Subjects

Adolescents from two studies completed survey-based measures on perceptions of time to walk to food retail outlets from home, purchasing patterns of SSB and fast and convenience store items, perceptions of personal safety and pedestrian infrastructure, and demographic characteristics. Descriptive analysis, Spearman correlations and multivariate linear regression, accounting for clustering, were conducted.

Results

There were 634 adolescents, approximately half male, predominantly white, with a middle-class background. Greater perceived time to food outlets was associated with less frequent purchasing of SSB, convenience store foods and fast-food items. Multivariate models showed that a perceived shorter walking time (i.e. 1−5 v. 31+ min) was significantly associated with more SSB purchasing. SSB purchases were also significantly associated with the number of food outlets within a 10 min walk (B = 0·05, P = 0·02).

Conclusions

A reduction in consumption of SSB and other energy-dense snacks is an important obesity prevention approach. An approach offering alternatives or reducing exposure in addition to education to alter purchasing habits may contribute to improving dietary habits and reducing the obesity epidemic.
Impact of ionospheric scintillation on GNSS receiver tracking performance over Latin America: Introducing the concept of tracking jitter variance maps
Authors: Sreeja V. , Aquino M. , Elmas Z. G.
Published: August 2011

Scintillations are rapid fluctuations in the phase and amplitude of transionospheric radio signals caused by small‐scale ionospheric plasma density irregularities. In the case of Global Navigation Satellite System (GNSS) receivers, scintillations can cause cycle slips, degrade the positioning accuracy and when severe enough can even lead to complete loss of signal lock. This study presents for the first time an assessment of GNSS receiver signal tracking performance under scintillating conditions, by the analysis of receiver phase lock loop (PLL) jitter variance maps. These maps can potentially assist users when faced with such conditions; a potential application envisaged for these maps would be in the form of a tool to provide users with information about “current (or expected, if some sort of prediction can be developed in follow on research) tracking conditions” under scintillation; another possibility would be to use the technique described by Aquino et al. (2009) to mitigate against the effects of ionospheric scintillation. In this paper these maps were constructed for scintillation events that were observed in the field during 9–11 March 2011 over Presidente Prudente (22.1°S, 51.4°W, dip latitude ∼12.3°S) in Brazil, a location close to the Equatorial Ionisation Anomaly (EIA) crest in Latin America. Results show that the jitter variances estimated for all the simultaneously observed satellite‐to‐receiver links during the premidnight hours on 9 and 11 March 2011 increase during the enhanced scintillation levels, indicating the likelihood for cycle slips, loss of signal lock, and degraded accuracy in the observations.
High efficiency transfection of thymic epithelial cell lines and primary thymic epithelial cells by Nucleofection
Authors: O’Neil Richard , Wei Qiaozhi , Condie Brian
Published: August 2011

Thymic epithelial cells (TECs) are required for the development and differentiation of T cells and are sufficient for the positive and negative selection of developing T cells. Although TECs play a critical role in T cell biology, simple, efficient and readily scalable methods for the transfection of TEC lines and primary TECs have not been described. We tested the efficiency of Nucleofection for the transfection of 4 different mouse thymic epithelial cell lines that had been derived from cortical or medullary epithelium. We also tested primary mouse thymic epithelial cells isolated from fetal and postnatal stages. We found that Nucleofection was highly efficient for the transfection of thymic epithelial cells, with transfection efficiencies of 30-70% for the cell lines and 15-35% for primary TECs with low amounts of cell death. Efficient transfection by Nucleofection can be performed with established cortical and medullary thymic epithelial cell lines as well as primary TECs isolated from E15.5 day fetal thymus or postnatal day 3 or 30 thymus tissue. The high efficiency of Nucleofection for TEC transfection will enable the use of TEC lines in high throughput transfection studies and simplifies the transfection of primary TECs for in vitro or in vivo analysis.
High field properties and energy storage in nanocomposite dielectrics of poly(vinylidene fluoride-hexafluoropropylene)
Authors: Tomer V. , Manias E. , Randall C. A.
Published: August 2011

Poly(vinylidene fluoride) (PVDF) has generated interest for use in electrical energy storage, mostly due to its high dielectric constant compared to other polymers. There still exist challenges, such as its high energy losses, that have prevented large scale commercialization of PVDF-based capacitors, but progress is continuously being made. In this paper we explore a promising route to improve the energy storage performance of PVDF, through a synergy of HFP comonomers and of kaolinite clay nanofillers. This study shows that the addition of these high aspect ratio fillers to poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] copolymers does not increase the polar phase and, consequently, these composites exhibit markedly enhanced dielectric properties at high electric fields. Specifically, strained films of these composites exhibit reduced high field losses, markedly increased breakdown strength and, thus, large recoverable energy density values, in the range of 19 J/cm3.
Wave mode coupling due to plasma wakes in two-dimensional plasma crystals: In-depth view
Authors: Couëdel L. , Zhdanov S. K. , Ivlev A. V. , Nosenko V. , Thomas H. M. , Morfill G. E.
Published: August 2011

Experiments with two-dimensional (2D) plasma crystals are usually carried out in rf plasma sheaths, where the interparticle interactions are modified due to the presence of plasma wakes. The wake-mediated interactions result in the coupling between wave modes in 2D crystals, which can trigger the mode-coupling instability and cause melting. The theory predicts a number of distinct fingerprints to be observed upon the instability onset, such as the emergence of a new hybrid mode, a critical angular dependence, a mixed polarization, and distinct thresholds. In this paper we summarize these key features and provide their detailed discussion, analyze the critical dependence on experimental parameters, and highlight the outstanding issues.
On a plasma having nonextensive electrons and positrons: Rogue and solitary wave propagation
Authors: El-Awady E. I. , Moslem W. M.
Published: August 2011

Generation of nonlinear ion-acoustic waves in a plasma having nonextensive electrons and positrons has been studied. Two wave modes existing in such plasma are considered, namely solitary and rogue waves. The reductive perturbation method is used to obtain a Korteweg-de Vries equation describing the system. The latter admits solitary wave pulses, while the dynamics of the modulationally unstable wave packets described by the Korteweg-de Vries equation gives rise to the formation of rogue excitation that is described by a nonlinear Schrödinger equation. The dependence of both solitary and rogue waves profiles on the nonextensive parameter, positron-to-ion concentration ratio, electron-to-positron temperature ratio, and ion-to-electron temperature ratio are investigated numerically. The results from this work are expected to contribute to the in-depth understanding of the nonlinear excitations that may appear in nonextensive astrophysical plasma environments, such as galactic clusters, interstellar medium, etc.
Plasma creation by terahertz electromagnetic radiation
Authors: Bratman V. L. , Zorin V. G. , Kalynov Yu. K. , Koldanov V. A. , Litvak A. G. , Razin S. V. , Sidorov A. V. , Skalyga V. A.
Published: August 2011

The results of experiments aimed at the study of the discharge in a focused beam of terahertz waves in argon under near-atmospheric pressures are presented. The range of electric fields and gas pressures, at which a breakdown occurs, is determined. The study of the discharge glow dynamics showed that the discharge starts at the maximum of the terahertz wave beam field and its front moved towards the radiation with the speed of about 105 cm/s into the region of the fields being significantly weaker than the breakdown value. Measurements of the ratio of wave transmission through the discharge allow one to conclude that the density of the plasma produced in the discharge exceeds 1015 cm−3. Some features of the terahertz discharge are discussed.
Short channel device performance of amorphous InGaZnO thin film transistor
Authors: Jeon Sanghun , Benayad Anass , Ahn Seung-Eon , Park Sungho , Song Ihun , Kim Changjung , Chung U-In
Published: August 2011

Short channel device performance of deep-submicron gate length oxide thin film transistor (TFT) with amorphous InGaZnO (a-IGZO) active semiconductor is presented. Remarkable electrical properties of short channel oxide TFT were achieved utilizing crucial structure and material optimization such as self aligned gate structure with homo junction, multi-channel with rounded corners, and high-κ gate dielectric. It was found that various device performance parameters of short channel-oxide TFTs were significantly influenced by materials, processes, and structural geometry, which should be more carefully designed.
Generating and enhancing lag synchronization of chaotic systems by white noise
Authors: Sun Zhongkui , Yang Xiaoli
Published: August 2011

In this paper, we study the crucial impact of white noise on lag synchronous regime in a pair of time-delay unidirectionally coupled systems. Our result demonstrates that merely via white-noise-based coupling lag synchronization could be achieved between the coupled systems (chaotic or not). And it is also demonstrated that a conventional lag synchronous regime can be enhanced by white noise. Sufficient conditions are further proved mathematically for noise-inducing and noise-enhancing lag synchronization, respectively. Additionally, the influence of parameter mismatch on the proposed lag synchronous regime is studied, by which we announce the robustness and validity of the new strategy. Two numerical examples are provided to illustrate the validity and some possible applications of the theoretical result.
High magnetoresistance at room temperature in p-i-n graphene nanoribbons due to band-to-band tunneling effects
Authors: Liang Gengchiau , Bala Kumar S. , Jalil M. B. A. , Tan S. G.
Published: August 2011

A large magnetoresistance effect is obtained at room-temperature by using p-i-n armchair-graphene-nanoribbon (GNR) heterostructures. The key advantage is the virtual elimination of thermal currents due to the presence of band gaps in the contacts. The current at B = 0 T is greatly decreased while the current at B > 0 T is relatively large due to the band-to-band tunneling effects, resulting in a high magnetoresistance ratio, even at room-temperature. Moreover, we explore the effects of edge-roughness, length, and width of GNR channels on device performance. An increase in edge-roughness and channel length enhances the magnetoresistance ratio while increased channel width can reduce the operating bias.
Accurate determination of the Gibbs energy of Cu–Zr melts using the thermodynamic integration method in Monte Carlo simulations
Authors: Harvey J.-P. , Gheribi A. E. , Chartrand P.
Published: August 2011

The design of multicomponent alloys used in different applications based on specific thermo-physical properties determined experimentally or predicted from theoretical calculations is of major importance in many engineering applications. A procedure based on Monte Carlo simulations (MCS) and the thermodynamic integration (TI) method to improve the quality of the predicted thermodynamic properties calculated from classical thermodynamic calculations is presented in this study. The Gibbs energy function of the liquid phase of the Cu–Zr system at 1800 K has been determined based on this approach. The internal structure of Cu–Zr melts and amorphous alloys at different temperatures, as well as other physical properties were also obtained from MCS in which the phase trajectory was modeled by the modified embedded atom model formalism. A rigorous comparison between available experimental data and simulated thermo-physical properties obtained from our MCS is presented in this work. The modified quasichemical model in the pair approximation was parameterized using the internal structure data obtained from our MCS and the precise Gibbs energy function calculated at 1800 K from the TI method. The predicted activity of copper in Cu–Zr melts at 1499 K obtained from our thermodynamic optimization was corroborated by experimental data found in the literature. The validity of the amplitude of the entropy of mixing obtained from the in silico procedure presented in this work was analyzed based on the thermodynamic description of hard sphere mixtures.
Temperature dependence of the thermoplastic formability in bulk metallic glasses
Authors: Bryn Pitt E. , Kumar Golden , Schroers Jan
Published: August 2011

The temperature dependence of the maximum strain a bulk metallic glass (BMG) can undergo in its supercooled liquid state under specified conditions is determined. This formability is measured experimentally over a wide temperature range using Zr35Ti30Cu8.25Be26.75 as an example BMG. When considering five different BMG formers, we found that the formability continuously increases with temperature. This behavior is ubiquitous among BMGs whose crystallization behavior can be described by steady state nucleation and diffusion limited growth. Therefore, in order to maximize the formability during thermoplastic forming of BMGs, the highest processing temperature should be chosen at which crystallization can still be avoided.
Pairwise additivity of energy components in protein-ligand binding: The HIV II protease-Indinavir case
Authors: Ucisik Melek N. , Dashti Danial S. , Faver John C. , Merz Kenneth M.
Published: August 2011

An energy expansion (binding energy decomposition into n-body interaction terms for n ≥ 2) to express the receptor-ligand binding energy for the fragmented HIV II protease-Indinavir system is described to address the role of cooperativity in ligand binding. The outcome of this energy expansion is compared to the total receptor-ligand binding energy at the Hartree-Fock, density functional theory, and semiempirical levels of theory. We find that the sum of the pairwise interaction energies approximates the total binding energy to ∼82% for HF and to >95% for both the M06-L density functional and PM6-DH2 semiempirical method. The contribution of the three-body interactions amounts to 18.7%, 3.8%, and 1.4% for HF, M06-L, and PM6-DH2, respectively. We find that the expansion can be safely truncated after n = 3. That is, the contribution of the interactions involving more than three parties to the total binding energy of Indinavir to the HIV II protease receptor is negligible. Overall, we find that the two-body terms represent a good approximation to the total binding energy of the system, which points to pairwise additivity in the present case. This basic principle of pairwise additivity is utilized in fragment-based drug design approaches and our results support its continued use. The present results can also aid in the validation of non-bonded terms contained within common force fields and in the correction of systematic errors in physics-based score functions.
High-temperature characteristics of Seebeck coefficients for AlInN alloys grown by metalorganic vapor phase epitaxy
Authors: Zhang Jing , Kutlu Songul , Liu Guangyu , Tansu Nelson
Published: August 2011

The Seebeck coeeficients of AlInN alloys, grown by metalorganic vapor phase epitaxy, with In-contents (x) from 0.38% up to 21.34%, were characterized and analyzed from room temperature (T = 300 K) up to high temperature (T = 382 K). The Seebeck coefficients of the n-type AlInN alloys show significant enhancement at higher temperature up to 382 K, in comparison to those measured at room temperature. Large Seebeck coefficients (602.0– 1233.2 μV/K) were obtained for the lattice-matched Al0.83In0.17N alloy (n = 5.1 × 1018 cm−3) from T = 300 K up to T = 382 K. The improvement of Seebeck coefficients for the n-type AlInN alloys will lead to ∼1.5–4 times improvement of the thermopower at higher temperatures.
Ordinary differential equation for local accumulation time
Authors: Berezhkovskii Alexander M.
Published: August 2011

Cell differentiation in a developing tissue is controlled by the concentration fields of signaling molecules called morphogens. Formation of these concentration fields can be described by the reaction-diffusion mechanism in which locally produced molecules diffuse through the patterned tissue and are degraded. The formation kinetics at a given point of the patterned tissue can be characterized by the local accumulation time, defined in terms of the local relaxation function. Here, we show that this time satisfies an ordinary differential equation. Using this equation one can straightforwardly determine the local accumulation time, i.e., without preliminary calculation of the relaxation function by solving the partial differential equation, as was done in previous studies. We derive this ordinary differential equation together with the accompanying boundary conditions and demonstrate that the earlier obtained results for the local accumulation time can be recovered by solving this equation.
Plasma equilibria with multiple ion species: Equations and algorithm
Authors: Galeotti L. , Barnes D. C. , Ceccherini F. , Pegoraro F.
Published: August 2011

Axisymmetric equilibrium of a magnetically confined plasma with multiple ion species is considered. To describe hot plasmas with isothermal surfaces, we adopt a formulation consistent with zero poloidal ion flow. This formulation includes all magnetic field components and also correctly includes all effects of toroidal ion rotation. There are two free surface functions for each species and a third which is determined by a differential equation relating surface functions per species. We have developed and implemented an algorithm for the solution of the resulting nonlinear equations and found solutions with large charge and mass contrast among the ion species for both compact (r = 0 included) and annular (r = 0 excluded) domains. Our solution method allows for arbitrary domain shapes, includes far-field conditions, and treats any combination of electrically conducting or insulating walls. Appropriate surface functions are used to describe the transition from closed to open field plasma in a reasonable manner. Solutions for advanced fuel cycle fusion systems (both D–3He and p–11B) are presented to illustrate the power of the method. Finally, we briefly discuss the special issues associated with obtaining very elongated solutions and describe the algorithm for implementing these features.
Temperature and scattering contrast dependencies of thickness fluctuations in surfactant membranes
Authors: Nagao Michihiro
Published: August 2011

Temperature and scattering contrast dependencies of thickness fluctuations have been investigated using neutron spin echo spectroscopy in a swollen lamellar phase composed of nonionic surfactant, water, and oil. In the present study, two contrast conditions are examined; one is the bulk contrast, which probes two surfactant monolayers with an oil layer as a membrane, and the other is the film contrast, which emphasizes an individual surfactant monolayer. The thickness fluctuations enhance dynamics from the bending fluctuations, and are observed in a similar manner in both contrast conditions. Thickness fluctuations can be investigated regardless of the scattering contrast, though film contrasts are better to be employed in terms of the data quality. The thickness fluctuation amplitude is constant over the measured temperature range, including in the vicinity of the phase boundary between the lamellar and micellar phases at low temperature and the boundary between the lamellar and bicontinuous phases at high temperature. The damping frequency of the thickness fluctuations is well scaled using viscosity within the membranes at low temperature, which indicates the thickness fluctuations are predominantly controlled by the viscosity within the membrane. On the other hand, in the vicinity of the phase boundary at high temperature, thickness fluctuations become faster without changing the mode amplitude.
Conformational flexibility and the mechanisms of allosteric transitions in topologically similar proteins
Authors: Tripathi Swarnendu , Portman John J.
Published: August 2011

Conformational flexibility plays a central role in allosteric transition of proteins. In this paper, we extend the analysis of our previous study [S. Tripathi and J. J. Portman, Proc. Natl. Acad. Sci. U.S.A. 106, 2104 (2009)] to investigate how relatively minor structural changes of the meta-stable states can significantly influence the conformational flexibility and allosteric transition mechanism. We use the allosteric transitions of the domains of calmodulin as an example system to highlight the relationship between the transition mechanism and the inter-residue contacts present in the meta-stable states. In particular, we focus on the origin of transient local unfolding (cracking), a mechanism that can lower free energy barriers of allosteric transitions, in terms of the inter-residue contacts of the meta-stable states and the pattern of local strain that develops during the transition. We find that the magnitude of the local strain in the protein is not the sole factor determining whether a region will ultimately crack during the transition. These results emphasize that the residue interactions found exclusively in one of the two meta-stable states is the key in understanding the mechanism of allosteric conformational change.
Thermoelectric power factor enhancement by ionized nanoparticle scattering
Authors: Bahk Je-Hyeong , Bian Zhixi , Zebarjadi Mona , Santhanam Parthiban , Ram Rajeev , Shakouri Ali
Published: August 2011

We show theoretically that the thermoelectric power factor can be enhanced in degenerate semiconductors when embedded nanoparticles donate carriers to the matrix and replace conventional impurity dopants as scattering centers. Nanoparticle scattering rates calculated by the partial wave method indicate a mobility enhancement over materials with equivalent doping by isolated ionized impurities while the Seebeck coefficient remains nearly intact. We find that the thermoelectric power factor of In0.53Ga0.47As from 300 K to 800 K is enhanced by 15% – 30% by nanoparticles 3–4 nm in diameter.
Optical detection of the defects associated with the magnetic properties observed in GaN:Gd layers grown by reactive molecular beam epitaxy
Authors: Mishra J. K. , Singh B. P. , Dhar S.
Published: August 2011

The effect of annealing on the magnetic and the optoelectronic properties of Gd-doped GaN layers, which are grown by reactive molecular beam epitaxy technique, has been investigated using photoluminescence, photoconductivity, and vibrating sample magnetometry techniques. The study reveals that the multiple types of defects are formed in GaN layers during the Gd incorporation. However, the density of only one defect type, which results in a strong luminescence feature at 3.05 eV in the photoluminescence spectra recorded at low temperatures in GaN:Gd layers, has been found to decrease significantly upon annealing and at the same time, the saturation magnetization is also observed to reduce, suggesting that these defects are responsible for the magnetic properties observed in this system.
Measurements of electron avalanche formation time in W-band microwave air breakdown
Authors: Cook Alan M. , Hummelt Jason S. , Shapiro Michael A. , Temkin Richard J.
Published: August 2011

We present measurements of formation times of electron avalanche ionization discharges induced by a focused 110 GHz millimeter-wave beam in atmospheric air. Discharges take place in a free volume of gas, with no nearby surfaces or objects. When the incident field amplitude is near the breakdown threshold for pulsed conditions, measured formation times are ∼0.1–2 μs over the pressure range 5–700 Torr. Combined with electric field breakdown threshold measurements, the formation time data shows the agreement of 110 GHz air breakdown with the similarity laws of gas discharges.
High temperature measurements of metal contacts on epitaxial graphene
Authors: Nagareddy V. K. , Nikitina I. P. , Gaskill D. K. , Tedesco J. L. , Myers-Ward R. L. , Eddy C. R. , Goss J. P. , Wright N. G. , Horsfall A. B.
Published: August 2011

Electrical characteristics of Cr/Au and Ti/Au metal contacts on epitaxial graphene on 4H-SiC showed significant variations in resistance parameters at 300 K. These parameters decreased substantially as the temperature increased to 673 K. The work function, binding energy, and diffusion energy of the deposited metals were used to explain these observed variations. The quantitative analysis of our data demonstrates that non-reactive metals with higher work functions result in lower contact resistance, which can be further decreased by 70% using appropriate annealing. These results provide important information when considering epitaxial graphene for high temperature applications.
Field emission measure of the time response of individual semiconducting nanowires to laser excitation
Authors: Choueib M. , Ayari A. , Poncharal P. , Journet C. , Cojocaru C. S. , Martel R. , Purcell S. T.
Published: August 2011

A simple technique is explored to determine the temporal photo-response, τ, of individual semiconducting SiC and Si nanowires (NWs), with a high time resolution. Laser-assisted field emission (LAFE) from the NWs is first shown to be highly sensitive to continuous laser illumination. Pulsed illumination is then combined with measurements of the total energy distributions to determine τ which were rather large, 4–200 μs. The time response scaled roughly with the square of the NWs length and could be attributed to laser-induced heating. LAFE is thus a new tool for quantifying rapid thermo-optical effects in such nano-objects.
Sign reversal of dielectric anisotropy of ferroelectric liquid crystals doped with cadmium telluride quantum dots
Authors: Kumar A. , Silotia P. , Biradar A. M.
Published: August 2011

A small amount of cadmium telluride quantum dots (CdTe QDs) has been doped into various ferroelectric liquid crystals (FLCs) to observe the modifications in the alignment and dielectric anisotropy (Δɛ) of the composites. The CdTe QDs have induced a uniform homeotropic (HMT) alignment in most of the FLC mixtures. We observed an unexpected switching (from HMT to homogeneous configuration) of CdTe QDs doped FLC CS1026 (having positive Δɛ) by the application of high dc bias. This reverse switching has been attributed to the interaction between FLC molecules and CdTe QDs which caused the sign reversal of Δɛ of FLC CS1026.
Acceleration of a solid-density plasma projectile to ultrahigh velocities by a short-pulse ultraviolet laser
Authors: Badziak J. , Jabłoński S.
Published: August 2011

It is shown by means of particle-in-cell simulations that a high-fluence (≥1 GJ/cm2) solid-density plasma projectile can be accelerated up to sub-relativistic velocities by radiation pressure of an ultraviolet (UV) picosecond laser pulse of moderate values of dimensionless laser amplitude a0∼10. The efficiency of acceleration by the UV laser is significantly higher than in the case of long-wavelength (λ ∼ 1 μm) driver of a comparable value of a0, and the motion of the projectile is fairly well described by the “Light Sail” acceleration model.
Effect of electron transport layer crystallinity on the transient characteristics of inverted organic solar cells
Authors: Kang Yong-Jin , Su Kim Chang , Sung You Dae , Hoon Jung Sung , Lim Kyounga , Kim Do-Geun , Kim Jong-Kuk , Hyung Kim Soo , Shin Yu-Ri , Kwon Se-Hun , Kang Jae-Wook
Published: August 2011

We present how the crystallinity of the electron transport layer can dramatically influence the transient characteristics of organic solar cells. We employed an inverted cell structure using TiOx prepared by atomic layer deposition as an electron transport layer. The device possessing the amorphous phase TiOx exhibited a continuous increase in the device characteristics upon continuous illumination at ambient, which is attributed to the filling of shallow electron traps within the amorphous phase TiOx upon illumination. In contrast, the characteristics of the device with the crystalline phase TiOx showed a negligible increase upon continuous illumination.
Wavelength selective metal-semiconductor-metal photodetectors based on (Mg,Zn)O-heterostructures
Authors: Zhang Zhipeng , von Wenckstern Holger , Schmidt Matthias , Grundmann Marius
Published: August 2011

We report on the utilization of MgyZn1−yO/MgxZn1−xO heterostructures having two different Mg-contents (0 < y < x ≤ 0.5, wurtzite structure) for the construction of wavelength selective metal-semiconductor-metal ultraviolet photodetectors. The MgxZn1−xO thin film acts as an optical edge filter and the MgyZn1−yO layer is the active layer of the devices. A FWHM of only 7 nm was achieved for a photodetector operating around 3.4 eV and the center of band (370–325 nm) was shifted by different y:x-combinations. A maximum spectral photo response of about 1.8 A/W was achieved in visible-blind range. An internal gain mechanism in the device was observed and attributed to trapping of minority carriers at PdOz/(Mg,Zn)O-interface.
A study of spin isomer conversion kinetics in supercritical fluid hydrogen for cryogenic fuel storage technologies
Authors: Matthews Manyalibo J. , Petitpas Guillaume , Aceves Salvador M.
Published: August 2011

A detailed kinetic study of para-ortho hydrogen conversion under supercritical conditions using rotational Raman scattering is presented. Isochoric measurements of initially low ortho concentrations over temperatures 32 < T < 280 K and densities 0.014 < ρ < 0.060 g/cm3 were used to derive kinetic rate constants k(ρ, T) by solving an autocatalytic kinetic rate equation. At low ortho concentrations and T < 100 K, k is found to be ∼2× higher than previous results based on thermal conductivity measurements, decreasing weakly with temperature, similar to Wigner’s original paramagnetic theory. Accurate modeling of k(ρ, T) is critical in predicting cryogenic hydrogen fuel tank dormancy performance for hydrogen-power vehicles.
Incorporation of a light and carrier collection management nano-element array into superstrate a-Si:H solar cells
Authors: Jun Nam Wook , Ji Liming , Benanti Travis L. , Varadan Vasundara V. , Wagner Sigurd , Wang Qi , Nemeth William , Neidich Douglas , Fonash Stephen J.
Published: August 2011

Superstrate a-Si:H solar cells incorporating a nano-column array for light and photocarrier collection have been fabricated and evaluated. It is found that the short circuit current density (JSC) is significantly increased while the open circuit voltage and fill factor are not detrimentally affected by this architecture. Numerical analysis of JSC matches experiment and shows that the enhanced JSC observed is due to both effective absorber thickness and photonic-plasmonic effects. Further analysis shows that this nano-column architecture can lead to a 42% increase in conversion efficiency over that of the planar control for a 200 nm absorber thickness cell.
Ultra-wide bandwidth piezoelectric energy harvesting
Authors: Hajati Arman , Kim Sang-Gook
Published: August 2011

Here, we present an ultra wide-bandwidth energy harvester by exploiting the nonlinear stiffness of a doubly clamped microelectromechanical systems (MEMSs) resonator. The stretching strain in a doubly clamped beam shows a nonlinear stiffness, which provides a passive feedback and results in amplitude-stiffened Duffing mode resonance. This design has been fabricated into a compact MEMS device, which is about the size of a US quarter coin. Based on the open circuit voltage measurement, it is expected to have more than one order of magnitude improvement in both bandwidth (more than 20% of the peak frequency) and power density (up to 2 W/cm3) in comparison to the devices previously reported.
Faces in the Mist: Illusory Face and Letter Detection
Authors: Rieth Cory A. , Lee Kang , Lui Jiangang , Tian Jie , Huber David E.
Published: August 2011

We report three behavioral experiments on the spatial characteristics evoking illusory face and letter detection. False detections made to pure noise images were analyzed using a modified reverse correlation method in which hundreds of observers rated a modest number of noise images (480) during a single session. This method was originally developed for brain imaging research, and has been used in a number of fMRI publications, but this is the first report of the behavioral classification images. In Experiment 1 illusory face detection occurred in response to scattered dark patches throughout the images, with a bias to the left visual field. This occurred despite the use of a fixation cross and expectations that faces would be centered. In contrast, illusory letter detection (Experiment 2) occurred in response to centrally positioned dark patches. Experiment 3 included an oval in all displays to spatially constrain illusory face detection. With the addition of this oval the classification image revealed an eyes/nose/mouth pattern. These results suggest that face detection is triggered by a minimal face-like pattern even when these features are not centered in visual focus.
San Lorenzo and the Poggendorff Illusion in Ravenna
Authors: Daneyko Olga , Stucchi Natale , Zavagno Daniele
Published: August 2011

In the Mausoleum of Galla Placidia (Ravenna, Italy), the San Lorenzo lunette shows two peculiar visual effects: a transparency effect of gold seen through gold and perceptual collinearity between two parts of a cross which are physically misaligned. Both effects are found within the area of the halo surrounding the saint's head. In this work we addressed the problem posed by the physical misalignment of the cross. Our hypothesis is that the physical misalignment went unnoticed throughout history because the artist produced a perceptual alignment to correct for the Poggendorff illusion. Hence, we asked observers to align two ends of a cross in a reproduction showing the silhouette of San Lorenzo's torso holding the cross. Results support our hypothesis: both direction and magnitude of adjustments comply with the alignment in the original mosaic.
Index insurance for pro-poor conservation of hornbills in Thailand
Authors: Chantarat Sommarat , Barrett Christopher B. , Janvilisri Tavan , Mudsri Sittichai , Niratisayakul Chularat , Poonswad Pilai
Published: August 2011

This study explores the potential of index insurance as a mechanism to finance community-based biodiversity conservation in areas where a strong correlation exists between natural disaster risk, keystone species populations, and the well-being of the local population. We illustrate this potential using the case of hornbill conservation in the Budo-Sungai Padi rainforests of southern Thailand, using 16-y hornbill reproduction data and 5-y household expenditures data reflecting local economic well-being. We show that severe windstorms cause both lower household expenditures and critical nest tree losses that directly constrain nesting capacity and so reduce the number of hornbill chicks recruited in the following breeding season. Forest residents’ coping strategies further disturb hornbills and their forest habitats, compounding windstorms’ adverse effects on hornbills’ recruitment in the following year. The strong statistical relationship between wind speed and both hornbill nest tree losses and household expenditures opens up an opportunity to design wind-based index insurance contracts that could both enhance hornbill conservation and support disaster-affected households in the region. We demonstrate how such contracts could be written and operationalized and then use simulations to show the significant promise of unique insurance-based approaches to address weather-related risk that threatens both biodiversity and poor populations.
The effect of a protected area on the tradeoffs between short-run and long-run benefits from mangrove ecosystems
Authors: McNally Catherine G. , Uchida Emi , Gold Arthur J.
Published: August 2011

Protected areas are used to sustain biodiversity and ecosystem services. However, protected areas can create tradeoffs spatially and temporally among ecosystem services, which can affect the welfare of dependent local communities. This study examines the effect of a protected area on the tradeoff between two extractive ecosystem services from mangrove forests: cutting mangroves (fuelwood) and harvesting the shrimp and fish that thrive if mangroves are not cut. We demonstrate the effect in the context of Saadani National Park (SANAPA) in Tanzania, where enforcement of prohibition of mangrove harvesting was strengthened to preserve biodiversity. Remote sensing data of mangrove cover over time are integrated with georeferenced household survey data in an econometric framework to identify the causal effect of mangrove protection on income components directly linked to mangrove ecosystem services. Our findings suggest that many households experienced an immediate loss in the consumption of mangrove firewood, with the loss most prevalent in richer households. However, all wealth classes appear to benefit from long-term sustainability gains in shrimping and fishing that result from mangrove protection. On average, we find that a 10% increase in the mangrove cover within SANAPA boundaries in a 5-km
2
radius of the subvillage increases shrimping income by approximately twofold. The creation of SANAPA shifted the future trajectory of the area from one in which mangroves were experiencing uncontrolled cutting to one in which mangrove conservation is providing gains in income for the local villages as a result of the preservation of nursery habitat and biodiversity.