bluuebunny/crossref_metadata_2025 huggingface dataset:
Singularity, isotropy, and velocity transmission evaluation of a three translational degrees-of-freedom parallel robot
Authors: Zhao Yongjie
Published: May 2012

Performance evaluation of a parallel robot is a multicriteria problem. By taking Delta robot as an object of study, this paper presents the kinematic performance evaluation of a three translational degrees-of-freedom parallel robot from the viewpoint of singularity, isotropy, and velocity transmission. It is shown that the determinant of a Jacobian matrix cannot measure the distance from the singular configuration due to the existing inverse kinematic singularity of a Delta robot. The determinants of inverse and direct kinematic Jacobian matrices are adopted for the measurement of distance from the singular configuration based on the theory of numerical linear dependence. The denominator of the Jacobian matrix will be lost in the computation of the condition number when the end-effector is on the centerline of the workspace, so the Delta robot may also be nearly at a singular configuration when the condition number of the Jacobian matrix is equal to 1. The velocity transmission index whose physical meaning is the maximum input angular velocity when the end-effector translates in the unit velocity is presented. The evaluation of singularity, isotropy, and velocity transmission of a Delta robot is investigated by simulation. The velocity transmission index can also be used for the velocity transmission evaluation of a parallel robot with pure rotational degrees-of-freedom based on the principle of similarity. The physical meaning is modified to be the maximum input velocity when the end-effector rotates in the unit angular velocity.
Student Perception of High Fidelity Medical Simulation for an International Trauma Life Support Course
Authors: Kim Tae Eung , Reibling Ellen T. , Denmark Kent T.
Published: May 2012

Background: High fidelity medical simulators (HFMS) are accepted tools for health care instruction. The use of HFMS was incorporated into an International Trauma Life Support course, and course participants were surveyed regarding attitudes toward HFMS.

Methods: Course participants, including physicians, nurses, and prehospital personnel, were given pre- and post-course questionnaires measuring their confidence in knowledge and treatment of trauma resuscitation, as well as their attitudes towards the utility and realism of immersive simulation. The participants were randomly assigned to take a course examination either before or after their simulator session.

Results: Thirteen course participants of varying backgrounds and degrees of clinical experience were surveyed and tested. All surveyed areas improved following simulator training, including comfort level with simulation as a training method (17%), perception of the realism of HFMS (15%), and reported self-confidence in knowledge, experience and training in trauma care (27%). Test scores were improved in the post-simulation group as opposed to the pre-simulation group (86% pass rate in the post-simulation test group versus 50% pass rate in the pre-simulation test group).

Conclusions: High fidelity medical simulation was accepted by medical professionals of different backgrounds and experience. Attitudes towards simulation and self-confidence improved after simulator sessions, as did test scores, suggesting improved comprehension and retention of course materials. Further testing is required to validate the findings of this small, observational study.
Literature Review of Disaster Health Research in Japan: Focusing on Disaster Nursing Education
Authors: Kako Mayumi , Mitani Satoko , Arbon Paul
Published: May 2012

Introduction

Japan has a long history of disaster due to its location on the “Pacific Ring of Fire.” The frequency of earthquakes experienced in recent years has had significant influence on disaster health research in Japan. This paper describes disaster health research trends in Japan, with an emphasis on disaster nursing research.

Method

A systematic literature review of disaster health research in Japan from 2001 through 2007 was conducted for this study. The most commonly used database in Japan, Ichushi (version 4.0), was used for this literature review. The keywords and sub-keywords used were: disaster, disaster nursing, practice, education, ability, response, emergency, licensure, capability, function, prevention, planning and research. These keywords were sometimes used in combination to identify relevant literature.

Results

A total of 222 articles were reviewed. The number of research papers available increased gradually from 2001 through 2007. The most common articles used were found using the search category of “disaster nursing and research.” Among the search categories, “disaster nursing and education” also had a high number of publications. This category also peaked in 2007.

Conclusion

The recent experiences of natural disaster in Japan accelerated the impetus to explore and implement a disaster nursing concept into practice and nursing curricula. Further evidence-based studies to develop methodology and other areas of studies in disaster nursing, including other language databases are to be expected in the future.

Kako M, Mitani S, Arbon P. Literature review of disaster health research in Japan: focusing on disaster nursing education. Prehosp Disaster Med. 2012;27(2):1-6.
Youth Work Service Providers' Attitudes Towards Computerized CBT for Adolescents
Authors: Fleming Theresa , Merry Sally
Published: May 2012

Background:Attitudes of social service providers towards computerized CBT (cCBT) might affect use of cCBT by their clients and may provide important insights that should be considered in dissemination. There is no literature exploring the attitudes of providers of youth work services towards cCBT despite the likelihood of them having close relationships with young people at high risk of mental ill-health.Method:Focus groups and semi-structured interviews were undertaken with a total of 40 providers (21 youth workers and social service staff providing alternative schooling, justice or other intensive youth work programmes to adolescents, 6 youth service managers, 2 trainers, 5 peer leaders and 6 trainees).Results:Participants considered supporting young people who were distressed to be an important part of their role. They were generally interested in cCBT, especially those who were more mental health oriented and those who saw a cCBT programme in action. Their greatest concerns regarding cCBT related to it possibly displacing human contact, while advantages were seen as its appeal to young people and its potential therapeutic power. They would utilize cCBT in a range of ways, with many wishing to offer it in group settings. Training and resources would be required for them to use cCBT.Conclusions:Many providers of youth work services would like to be involved in the use of cCBT; this might extend the reach of cCBT to vulnerable young people. They would wish to utilize cCBT in ways that fit their current approaches. Providers’ opinions need to be considered in the dissemination of cCBT.
Shared information structure: Evidence from cross-linguistic priming
Authors: FLEISCHER ZUZANNA , PICKERING MARTIN J. , MCLEAN JANET F.
Published: May 2012

This study asked whether bilinguals construct a language-independent level of information structure for the sentences that they produce. It reports an experiment in which a Polish–English bilingual and a confederate of the experimenter took turns to describe pictures to each other and to find those pictures in an array. The confederate produced a Polish active, passive, or conjoined noun phrase, or an active sentence with object–verb–subject order (OVS sentence). The participant responded in English, and tended to produce a passive sentence more often after a passive or an OVS sentence than after a conjoined noun phrase or active sentence. Passives and OVS sentences are syntactically unrelated but share information structure, in that both assign emphasis to the patient. We therefore argued that bilinguals construct a language-independent level of information structure during speech.
How does linguistic competence enhance cognitive functions in children? A study in multilingual children with different linguistic competences
Authors: VIDESOTT GERDA , DELLA ROSA PASQUALE ANTHONY , WIATER WERNER , FRANCESCHINI RITA , ABUTALEBI JUBIN
Published: May 2012

The aim of the present study was to investigate the attentional mechanisms of multilingual children with differential degrees of language competence. For this purpose, 118 children (61 female/57 male; mean age 10.9 years (SD = 0.29); early acquisition multilinguals) from the Ladin valleys in South Tyrol, Italy, performed the Attentional Network Test (ANT). Our results proved that proficiency levels in early multilingual children may play a crucial role in the development and enhancement of the alerting component of the attentional system. Interestingly enough, we were able to deduce that linguistic competence rather than competence in other skill domains may have a decisive role in the alerting component. We suggest that the peculiarity of highly competent multilinguals relies on their ability to better detect, and consequently react faster to, the target stimulus than their less competent multilingual peers.
An examination of environmental correlates with childhood height-for-age in Ghana
Authors: Nikoi Ebenezer , Anthamatten Peter
Published: May 2012

Objective

The relationship between a child's environment and nutritional status is difficult to examine yet could offer an important guide to policy. The objective of the present work was to examine individual and environmental correlates with childhood height-for-age in Ghana.

Design

Data were derived from the 2008 MEASURE Demographic and Health Survey in Ghana, the 2000 Ghana Population and Housing Census, and the World Wide Fund for Nature's eco-regions database. A generalized linear mixed regression model was used to estimate the effects of individual and environmental correlates on height-for-age.

Subjects

The study examined 2225 Ghanaian children aged 0–59 months.

Setting

The setting was all districts in Ghana for the year 2008.

Results

After accounting for individual characteristics of children, mothers and households, height-for-age was significantly associated with population density. Other significantly associated variables in the final model were the age of the child, vaccination status, the size of the child at birth, months of breast-feeding, mother's BMI, whether the child's mother had health insurance and wealth quintile.

Conclusions

In addition to a number of characteristics of the children and their households, the social milieu is important to understanding differences in height-for-age among children in Ghana. The biophysical environment was not associated with height-for-age.
Health behaviours and health-care utilization in Canadian schoolchildren
Authors: Kirk Sara FL , Kuhle Stefan , Ohinmaa Arto , Veugelers Paul J
Published: May 2012

Objective

Poor nutritional habits and physical inactivity are two health behaviours believed to be linked with increasing rates of overweight and obesity in children. The objective of the present study was to determine whether children who reported healthier behaviours, specifically in relation to nutrition and physical activity, also had lower health-care utilization.

Design

Population-based cross-sectional study, linking survey data from the 2003 Children's Lifestyle and School Performance Study (CLASS) with Nova Scotia administrative health data. Health-care utilization was defined as both (i) the total physician costs and (ii) the number of physician visits, for each child from 2001 to 2006. Exposures were two indices of healthy eating, the Diet Quality Index and the Healthy Eating Index, and self-reported physical activity and screen time behaviours.

Setting

Elementary schools in the Canadian province of Nova Scotia.

Subjects

Grade 5 students and their parents; of the 5200 students who participated in CLASS and completed surveys, 4380 (84 %) could be linked with information in the administrative data sets.

Results

The study found a relationship between both indices of healthy eating and a borderline significant trend towards lower health-care utilization in this population sample of children. No statistically significant relationships were seen for physical activity or screen time.

Conclusions

Both measures of diet quality produced similar results. The study suggests that healthy eating habits established in childhood may be associated with lower health-care utilization, although further research over a longer time frame is needed to demonstrate statistical significance.
ICAT: Development of an Internet-Based Data Collection Method for Ecological Momentary Assessment Using Personal Cell Phones
Authors: Kuntsche Emmanuel , Labhart Florian
Published: May 2012

Abstract. Rapid advances in mobile data-transfer technologies offer new possibilities in the use of cell phones to conduct assessments of a person’s natural environment in real time. This paper describes features of a new Internet-based, cell phone-optimized assessment technique (ICAT), which consists of a retrospective baseline assessment combined with text messages sent to the participants’ personal cell phones providing a hyperlink to an Internet-stored cell phone-optimized questionnaire. Two participation conditions were used to test variations in response burden. Retention rates, completion rates, and response times in different subgroups were tested by means of χ² tests, Cox regression, and logistic regression. Among the 237 initial participants, we observed a retention rate of 90.3% from the baseline assessment to the cell-phone part, and 80.4% repeated participation in the 30 daily assessments. Each day, 40–70% of the questionnaires were returned, a fourth in less than 3 minutes. Qualitative interviews underscored the ease of use of ICAT. This technique appears to be an innovative, convenient, and cost-effective way of collecting data on situational characteristics while minimizing recall bias. Because of its flexibility, ICAT can be applied in various disciplines, whether as part of small pilot studies or large-scale, crosscultural, and multisite research projects.
On whistler mode wave scattering from density irregularities in the upper ionosphere
Authors: Kuzichev I. V.
Published: May 2012

This work concerns the problem of a whistler mode wave exit to the ground. After propagation in the magnetosphere a wave, in general, falls on the ionosphere with the angle of incidence outside the transmission cone. Such waves do not reach the Earth experiencing total internal reflection at the atmosphere‐ionosphere boundary. To explain wave exit to the ground, we follow up on the idea of wave scattering on small‐scale irregularities in the ionosphere. Interaction with these irregularities excites harmonics inside the transmission cone. Using the Green function method, we derive an integral equation for the wavefield containing all modes possible for a given frequency, solve this equation in the Born approximation, and obtain an expression for the energy flux of the waves which were scattered into the transmission cone.
Estimating annual precipitation for the Colorado River Basin using oceanic‐atmospheric oscillations
Authors: Kalra Ajay , Ahmad Sajjad
Published: May 2012

Estimating long‐lead time precipitation under the stress of increased climatic variability is a challenging task in the field of hydrology. A modified Support Vector Machine (SVM) based framework is proposed to estimate annual precipitation using oceanic‐atmospheric oscillations. Oceanic‐atmospheric oscillations, consisting of Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and El Niño–Southern Oscillation (ENSO) for a period of 1900–2008, are used to generate annual precipitation estimates with a 1 year lead time. The SVM model is applied to 17 climate divisions encompassing the Colorado River Basin in the western United States. The overall results revealed that the annual precipitation in the Colorado River Basin is significantly influenced by oceanic‐atmospheric oscillations. The long‐term precipitation predictions for the Upper Colorado River Basin can be successfully obtained using a combination of PDO, NAO, and AMO indices, whereas coupling AMO and ENSO results in improved precipitation predictions for the Lower Colorado River Basin. The results also show that the SVM model provides better precipitation estimates compared to the Artificial Neural Network and Multivariate Linear Regression models. The annual precipitation estimates obtained using the modified SVM modeling framework may assist water managers in statistically understanding the hydrologic response in relation to large scale climate patterns within the Colorado River Basin.
Next generation science standards available for comment
Authors: Asher Pranoti
Published: May 2012

The first public draft of the Next Generation Science Standards (NGSS) is now available for public comment. Feedback on the standards is sought from people who have a stake in science education, including individuals in the K–12, higher education, business, and research communities. Development of NGSS is a state‐led effort to define the content and practices students need to learn from kindergarten through high school. NGSS will be based on the U.S. National Research Council's reportFramework for K–12 Science Education.
Radić receives Cryosphere Young Investigator Award: Citation
Authors: Hock Regine , Clarke Garry
Published: May 2012

Valentina Radić received the 2011 Cryosphere Young Investigator Award at the 2011 AGU Fall Meeting, held 5–9 December in San Francisco, Calif. The award is for “a significant contribution to cryospheric science and technology.”
Winds influence Bering Shelf circulation
Authors: Balcerak Ernie
Published: May 2012

Circulation over the Bering Sea shelf and between the shelf and the adjacent deep basin affects the ecosystem through nutrient exchange, egg and larvae dispersal, and changes in temperature and salinity. Using numerical models and observations, Danielson et al. present a new simple framework showing how circulation on the Bering shelf varies with wind forcing. They f n d two primary modes of wind forcing, and changes in wind direction tend to reverse the flow around the shelf. Northwesterly winds, which are more common, promote off‐shelf transport along the majority of the continental slope, while southeasterly winds, which are less frequent, are associated with greater on‐shelf transport. The study improves overall understanding of the Bering shelf circulation. (Geophysical Research Letters, doi:10.1029/2012GL051231, 2012)
Earthquake‐volcano interaction imaged by coda wave interferometry
Authors: Battaglia Jean , Métaxian Jean‐Philippe , Garaebiti Esline
Published: May 2012

Large earthquakes are often assumed to influence the eruptive activity of volcanoes. A major challenge to better understand the causal relationship between these phenomena is to detect and image, in detail, all induced changes, including subtle, non‐eruptive responses. We show that coda wave interferometry can be used to image such earthquake‐induced responses, as recorded at Yasur volcano (Vanuatu) following a magnitude 7.3 earthquake which occurred 80 km from its summit. We use repeating Long‐Period events to show that the earthquake caused a sudden seismic velocity drop, followed by a slow partial recovery process. The spatial distribution of the response amplitude indicates an effect centered on the volcano. Our result demonstrates that, even if no major change in eruptive activity is observed, volcanoes will be affected by the propagation of large amplitude seismic waves through their structure, suggesting that Earthquake‐volcano interaction is likely a more common phenomenon than previously believed.
High‐resolution comparison of sediment dynamics under different forcing conditions in the bottom boundary layer of a shallow, micro‐tidal estuary
Authors: Ha Ho Kyung , Park Kyeong
Published: May 2012

Data for high‐resolution profiles of current velocity and suspended sediment concentration (SSC) were collected in bottom boundary layer (BBL) of Mobile Bay, Alabama. The data were used to study the vertical and temporal variability in SSC under various forcing conditions of tide, wind and freshwater discharge. During the winter stormy season, the background SSC was low (0.015–0.03 g l−1). An episodic storm‐induced erosion/resuspension was responsible for the short‐lasting high SSC in BBL. During the spring flooding period, the background SSC was relatively high (0.04–0.07 g l−1) likely due to the large amount of suspended sediment from the fluvial input and bed softening, and the contribution of wind forcing to sediment resuspension was somewhat enhanced by the destratification in BBL. When the freshwater discharge was extremely high (>5000 m3 s−1), the entire water column in shallow areas of the Bay was influenced by freshwater input. Therefore, the thermohaline anomaly's contribution to the stratification considerably weakened, while the SSC's contribution strengthened. When the freshwater discharge was relatively low (<5000 m3 s−1), a critical wind stress for sediment erosion (0.08–0.1 Pa) was observed to abruptly increase the SSC. Despite a micro‐tidal regime, Mobile Bay exhibited the cyclic erosion and deposition pattern induced by the tidal acceleration and deceleration.
Stratospheric water vapor and climate: Sensitivity to the representation in radiation codes
Authors: Maycock A. C. , Shine K. P.
Published: May 2012

There has been considerable interest in the climate impact of trends in stratospheric water vapor (SWV). However, the representation of the radiative properties of water vapor under stratospheric conditions remains poorly constrained across different radiation codes. This study examines the sensitivity of a detailed line‐by‐line (LBL) code, a Malkmus narrow‐band model and two broadband GCM radiation codes to a uniform perturbation in SWV in the longwave spectral region. The choice of sampling rate in wave number space (Δν) in the LBL code is shown to be important for calculations of the instantaneous change in heating rate (ΔQ) and the instantaneous longwave radiative forcing (ΔFtrop). ΔQ varies by up to 50% for values of Δν spanning 5 orders of magnitude, and ΔFtrop varies by up to 10%. In the three less detailed codes, ΔQdiffers by up to 45% at 100 hPa and 50% at 1 hPa compared to a LBL calculation. This causes differences of up to 70% in the equilibrium fixed dynamical heating temperature change due to the SWV perturbation. The stratosphere‐adjusted radiative forcing differs by up to 96% across the less detailed codes. The results highlight an important source of uncertainty in quantifying and modeling the links between SWV trends and climate.
Evaluation of Oxidative Stress in Overweight Subjects With or Without Metabolic Syndrome
Authors: Venturini Danielle , Simão Andréa N.C. , Scripes Nicole A. , Bahls Larissa D. , Melo Petrônio A.S. , Belinetti Francine M. , Lozovoy Marcell A.B. , Dichi Isaias
Published: May 2012

Although oxidative stress is considered the underlying mechanism by which dysfunctional metabolism occurs in obese subjects, there are few studies on oxidative stress in overweight subjects. The objective of this study was to verify the influence of metabolic syndrome (MetS) on oxidative stress and antioxidant defense in overweight subjects. There were 123 subjects (50 in the control group and 73 in the overweight group) chosen to participate in this cross‐sectional study. The control group included 50 healthy individuals with a BMI between 20 and 24.9 kg/m2 and without MetS. The overweight group included 73 subjects with a BMI between 25 and 29.9 kg/m2. Overweight subjects were divided into two groups: with MetS (29 subjects) and without MetS (44 subjects). Control group and overweight group subjects without MetS showed no differences in oxidative stress parameters and total antioxidant capacity (TRAP). Overweight subjects with MetS had higher hydroperoxide concentrations measured by chemiluminescence compared to the control group (P < 0.05), higher hydroperoxide and hydrogen peroxide concentrations determined by ferrous oxidation‐xylenol orange assay compared to overweight subjects without MetS (P < 0.001), and higher advanced oxidation protein product (AOPP) concentrations (P < 0.001) compared to the other groups. AOPP was directly correlated with uric acid concentrations. Overweight subjects with MetS had lower TRAP concentrations compared to the control group (P < 0.001). In conclusion, this study showed that overweight subjects with MetS, in contrast to overweight subjects without MetS, have a redox imbalance characterized by increased plasma oxidation and reduced antioxidant capacity.
Experiments and numerical simulation of mixing under supercritical conditions
Authors: Schmitt T. , Rodriguez J. , Leyva I. A. , Candel S.
Published: May 2012

Supercritical pressure conditions designate a situation where the working fluid pressure is above the critical point. Among these conditions, it is interesting to identify a transcritical range which corresponds to cases where the pressure is above the critical point, but the injection temperature is below the critical value. This situation is of special interest because it raises fundamental issues which have technological relevance in the analysis of flows in liquid rocket engines. This situation is here envisaged by analyzing the behavior of a nitrogen shear coaxial jet comprising an inner stream injected at temperatures close to the critical temperature and a coaxial flow at a higher temperature. Experiments are carried out both in the absence of external modulation and by imposing a large amplitude transverse acoustic field. Real gas large eddy simulations are performed for selected experiments. The combination of experiments and calculations is used to evaluate effects of injector geometry and operating parameters. Calculations retrieve what is observed experimentally when the momentum flux ratio of the outer to the inner stream \documentclass[12pt]{minimal}\begin{document}$J= (\rho _eu_e^2)/(\rho _iu_i^2)$\end{document}J=(ρeue2)/(ρiui2) is varied. Results exhibit the change in flow structure and the development of a recirculation region when this parameter exceeds a critical value. The instantaneous flow patterns for different momentum flux ratios are used in a second stage to characterize the dynamical behavior of the flow in terms of power spectral density of velocity and density fluctuations. Results obtained under acoustic modulation provide insight into mixing enhancement of coaxial streams with a view of its possible consequences in high frequency combustion instabilities. It is shown in particular that the presence of strong acoustic modulations notably reduces the high density jet core length, indicating an increased mixing efficiency. This behavior is more pronounced when the jet is placed at the location of maximum transverse velocity fluctuations.
The multiscale coarse-graining method. VIII. Multiresolution hierarchical basis functions and basis function selection in the construction of coarse-grained force fields
Authors: Das Avisek , Andersen Hans C.
Published: May 2012

The multiscale coarse-graining (MS-CG) method is a method for determining the effective potential energy function for a coarse-grained (CG) model of a molecular system using data obtained from molecular dynamics simulation of the corresponding atomically detailed model. The coarse-grained potential obtained using the MS-CG method is a variational approximation for the exact many-body potential of mean force for the coarse-grained sites. Here we propose a new numerical algorithm with noise suppression capabilities and enhanced numerical stability for the solution of the MS-CG variational problem. The new method, which is a variant of the elastic net method [Friedman et al., Ann. Appl. Stat. 1, 302 (2007)]10.1214/07-AOAS131, allows us to construct a large basis set, and for each value of a so-called “penalty parameter” the method automatically chooses a subset of the basis that is most important for representing the MS-CG potential. The size of the subset increases as the penalty parameter is decreased. The appropriate value to choose for the penalty parameter is the one that gives a basis set that is large enough to fit the data in the simulation data set without fitting the noise. This procedure provides regularization to mitigate potential numerical problems in the associated linear least squares calculation, and it provides a way to avoid fitting statistical error. We also develop new basis functions that are similar to multiresolution Haar functions and that have the differentiability properties that are appropriate for representing CG potentials. We demonstrate the feasibility of the combined use of the elastic net method and the multiresolution basis functions by performing a variational calculation of the CG potential for a relatively simple system. We develop a method to choose the appropriate value of the penalty parameter to give the optimal basis set. The combined effect of the new basis functions and the regularization provided by the elastic net method opens the possibility of using very large basis sets for complicated CG systems with many interaction potentials without encountering numerical problems in the variational calculation.
The multiscale coarse-graining method. X. Improved algorithms for constructing coarse-grained potentials for molecular systems
Authors: Das Avisek , Lu Lanyuan , Andersen Hans C. , Voth Gregory A.
Published: May 2012

The multiscale coarse-graining (MS-CG) method uses simulation data for an atomistic model of a system to construct a coarse-grained (CG) potential for a coarse-grained model of the system. The CG potential is a variational approximation for the true potential of mean force of the degrees of freedom retained in the CG model. The variational calculation uses information about the atomistic positions and forces in the simulation data. In principle, the resulting MS-CG potential will be an accurate representation of the true CG potential if the basis set for the variational calculation is complete enough and the canonical distribution of atomistic states is well sampled by the data set. In practice, atomistic configurations that have very high potential energy are not sampled. As a result there usually is a region of CG configuration space that is not sampled and about which the data set contains no information regarding the gradient of the true potential. The MS-CG potential obtained from a variational calculation will not necessarily be accurate in this unsampled region. A priori considerations make it clear that the true CG potential of mean force must be very large and positive in that region. To obtain an MS-CG potential whose behavior in the sampled region is determined by the atomistic data set, and whose behavior in the unsampled region is large and positive, it is necessary to intervene in the variational calculation in some way. In this paper, we discuss and compare two such methods of intervention, which have been used in previous MS-CG calculations for dealing with nonbonded interactions. For the test systems studied, the two methods give similar results and yield MS-CG potentials that are limited in accuracy only by the incompleteness of the basis set and the statistical error of associated with the set of atomistic configurations used. The use of such methods is important for obtaining accurate CG potentials.
ZnO nanowire based visible-transparent ultraviolet detectors on polymer substrates
Authors: Yu Hongbin , Ali Azhar Ebraheem , Belagodu Tej , Lim Swee , Dey Sandwip
Published: May 2012

The fabrication and characterization of fully visible-transparent and flexible ultraviolet (UV) detectors, on polyethylene 2,6-naphthalate (PEN) with active channels of zinc oxide nanowires and ohmic indium tin oxide contacts, are reported and discussed. The fabricated detector has an average transmittance of 80% in the visible spectral range and is most responsive at or below 370 nm, the onset of UV light, with a UV/vis rejection ratio of 1.42 × 103. A five orders of magnitude difference in the photocurrent, between UV illumination and dark conditions, are also observed. The single-sided UV response further shows that the PEN substrate performs well as a UV reflector. The noise analysis on the nanowire UV detector indicates a noise equivalent power and detectivity (D*) of 5.88 × 10−13 WHz−0.5 and 2.13 × 109 cm Hz0.5 W−1, respectively.
Dielectric and piezoelectric activities in (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 single crystals from 5 K to 300 K
Authors: Martin Florian , ter Brake H. J. M. , Lebrun Laurent , Zhang Shujun , Shrout Thomas
Published: May 2012

Lead based relaxor single crystals have raised a considerable interest due to their outstanding piezoelectric properties. These piezoelectric properties are temperature dependent and are known to decrease when the temperature is decreased. The aim of this paper is to study the variation of the dielectric constant, the elastic compliance, the coupling factor, the piezoelectric charge coefficient, and the mechanical quality factor for rhombohedral single crystals of (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMN-PT) poled along [001] in the 5 K–300 K temperature range. In particular, it has been shown that a relaxation phenomenon occurs around 100 K leading to a rapid decrease of the studied piezoelectric, mechanical, and dielectric constants just after a plateau. As a consequence, the similar behaviour of the dielectric constant, piezoelectric charge coefficient, and elastic compliance versus temperature leads to a temperature independent behaviour of the coupling factor above 100 K. This relaxation is also responsible for the minimum observed on the mechanical quality factor. By comparing the measured dielectric constant with the calculated one using the Landau-Ginsburg-Devonshire theory, this relaxation has been attributed to electrical charges freezing within the domain as the temperature is decreased.
Quantitative scheme for full-field polarization rotating fluorescence microscopy using a liquid crystal variable retarder
Authors: Lesoine John F. , Youn Lee Ji , Krogmeier Jeffrey R. , Kang Hyeonggon , Clarke Matthew L. , Chang Robert , Sackett Dan L. , Nossal Ralph , Hwang Jeeseong
Published: May 2012

We present a quantitative scheme for full-field polarization rotating fluorescence microscopy. A quarter-wave plate, in combination with a liquid crystal variable retarder, provides a tunable method to rotate polarization states of light prior to its being coupled into a fluorescence microscope. A calibration of the polarization properties of the incident light is performed in order to correct for elliptical polarization states. This calibration allows the response of the sample to linear polarization states of light to be recovered. Three known polarization states of light can be used to determine the average fluorescent dipole orientations in the presence of a spatially varying dc offset or background polarization-invariant fluorescence signal. To demonstrate the capabilities of this device, we measured a series of full-field fluorescence polarization images from fluorescent analogs incorporated in the lipid membrane of Burkitts lymphoma CA46 cells. The fluorescent lipid-like analogs used in this study are molecules that are labeled by either a DiI (1,1′-Dioctadecyl 3,3,3′,3′-Tetramethylindocarbocyanine) fluorophore in its head group or a Bodipy (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) molecule in its acyl chain. A spatially varying contrast in the normalized amplitude was observed on the cell surface, where the orientation of the DiI molecules is tangential to the cell membrane. The internally labeled cellular structures showed zero response to changes in linear polarization, and the net linear polarization amplitude for these regions was zero. This instrument provides a low cost calibrated method that may be coupled to existing fluorescence microscopes to perform investigations of cellular processes that involve a change in molecular orientations.
Structure of iron nanolayers embedded in amorphous alloys
Authors: Ghafari M. , Hahn H. , Brand R. A. , Mattheis R. , Yoda Y. , Kohara S. , Kruk R. , Kamali S.
Published: May 2012

Metalloid-free magnetic amorphous layers have been searched for their presumably high magnetic density. Multilayers of iron and amorphous boron-doped cobalt-iron have been studied with this in mind. Samples with various Fe thicknesses and a constant thickness of amorphous boron doped cobalt-iron were prepared. The aim was to reduce the metalloid content as much as possible but retaining the amorphous structure. Transmission electron microscopy, x-ray diffraction studies, and Mössbauer spectroscopy have been applied to elucidate physical properties. The iron-partial phonon density of states was measured showing differences between the amorphous and crystalline films.
The study of perpendicular magnetic anisotropy in CoFeB sandwiched by MgO and tantalum layers using polarized neutron reflectometry
Authors: Zhu T. , Yang Y. , Yu R. C. , Ambaye H. , Lauter V. , Xiao J. Q.
Published: May 2012

The perpendicular magnetic anisotropy (PMA) in CoFeB sandwiched by MgO and tantalum layers was investigated using anomalous Hall effect and polarized neutron reflectometry. It was found that a large PMA in the CoFeB above MgO layer was related to its low magnetization compared to the case of CoFeB under MgO layer. Using the sensitivity of neutrons to the absorption cross-section of boron, we unambiguously determined the depth profile of the boron distribution and showed that after annealing, most of the boron diffused to form a 2-nm-thick interface layer between the CoFeB and tantalum layers.
Observation and modeling of polycrystalline grain formation in Ge2Sb2Te5
Authors: Burr Geoffrey W. , Tchoulfian Pierre , Topuria Teya , Nyffeler Clemens , Virwani Kumar , Padilla Alvaro , Shelby Robert M. , Eskandari Mona , Jackson Bryan , Lee Bong-Sub
Published: May 2012

The relationship between the polycrystalline nature of phase change materials (such as Ge2Sb2Te5) and the intermediate resistance states of phase change memory (PCM) devices has not been widely studied. A full understanding of such states will require knowledge of how polycrystalline grains form, how they interact with each other at various temperatures, and how the differing electrical (and thermal) characteristics within the grains and at their boundaries combine through percolation to produce the externally observed electrical (and thermal) characteristics of a PCM device. We address the first of these tasks (and introduce a vehicle for the second) by studying the formation of fcc polycrystalline grains from the as-deposited amorphous state in undoped Ge2Sb2Te5. We perform ex situ transmission electron microscopy membrane experiments and then match these observations against numerical simulation. Ramped-anneal experiments show that the temperature ramp-rate strongly influences the median grain size. By truncating such ramped-anneal experiments at various peak temperatures, we convincingly demonstrate that the temperature range over which these grains are established is quite narrow. Subsequent annealing at elevated temperature appears to change these established distributions of grain sizes only slightly. Our numerical simulator—which models nuclei formation through classical nucleation theory and then tracks the subsequent time- and temperature-dependent growth of these grains—can match these experimental observations of initial grain distributions and crystallization temperature both qualitatively and quantitatively. These simulations show that the particular narrow temperature range over which crystallization occurs shifts as a function of temperature ramp-rate, which allows us to quantify the lower portions of the time-temperature-transformation map for Ge2Sb2Te5. Future experiments and extensions of the simulator to investigate temperature-dependent interactions between neighboring grains, and to study nucleation from within the melt-quenched amorphous state, are discussed.
Surface passivation of c-Si by atmospheric pressure chemical vapor deposition of Al2O3
Authors: Black Lachlan E. , McIntosh Keith R.
Published: May 2012

Atmospheric pressure chemical vapor deposition of Al2O3 is shown to provide excellent passivation of crystalline silicon surfaces. Surface passivation, permittivity, and refractive index are investigated before and after annealing for deposition temperatures between 330 and 520 °C. Deposition temperatures >440 °C result in the best passivation, due to both a large negative fixed charge density (∼2 × 1012 cm−2) and a relatively low interface defect density (∼1 × 1011 eV−1 cm−2), with or without an anneal. The influence of deposition temperature on film properties is found to persist after subsequent heat treatment. Correlations between surface passivation properties and the permittivity are discussed.
Nanometer-thin solid-state nanopores by cold ion beam sculpting
Authors: Kuan Aaron T. , Golovchenko Jene A.
Published: May 2012

Recent work on protein nanopores indicates that single molecule characterization (including DNA sequencing) is possible when the length of the nanopore constriction is about a nanometer. Solid-state nanopores offer advantages in stability and tunability, but a scalable method for creating nanometer-thin solid-state pores has yet to be demonstrated. Here we demonstrate that solid-state nanopores with nanometer-thin constrictions can be produced by “cold ion beam sculpting,” an original method that is broadly applicable to many materials, is easily scalable, and requires only modest instrumentation.
Analysis and modeling of the experimentally observed anomalous mobility properties of periodically Si-delta-doped GaN layers
Authors: Zheng Zhiyuan , Chen Zimin , Chen Yingda , Huang Shanjin , Fan Bingfeng , Xian Yulun , Jia Weiqing , Wu Zhisheng , Wang Gang , Jiang Hao
Published: May 2012

We report the anomalous mobility properties of Si-delta-doped GaN with periodically doping profile. Samples with different delta-doping periods or with varied Si source flow were investigated. It is found that for the short delta-doping-period (<26.5 nm) samples, the Hall mobility increases with decreasing electron concentration; while for the longer-doping-period samples, the situation is just the opposite. To interpret this observation, a two-layer model has been built up for long-period samples based on secondary ion mass spectroscopy measurements. The fitting results using this model are well consistent with the experimental data.
Stencil mask methodology for the parallelized production of microscale mechanical test samples
Authors: Shade Paul A. , Kim Sang-Lan , Wheeler Robert , Uchic Michael D.
Published: May 2012

A new methodology to parallelize the production of micromechanical test samples from bulk materials is reported. This methodology has been developed to produce samples with typical gage dimensions on the order of 20–200 μm, and also to minimize the reliance on conventional focused ion beam fabrication methods. The fabrication technique uses standard microelectronic process methods such as photolithography and deep-reactive ion etching to create high aspect ratio patterned templates—stencil masks—from a silicon wafer. In the present work, the stencil mask pattern consists of a linear row of tensile samples, where one grip of each sample is integrally attached to the bulk substrate. Once fabricated, the stencil mask is placed on top of a pre-thinned substrate, and the pattern and substrate are co-sputtered using a broad ion beam milling system, which ultimately results in the transfer of the mask pattern into the substrate. The methodology is demonstrated using a Si stencil mask and a polycrystalline Ni foil to manufacture an array of metallic micro-tensile samples.
From small aromatic molecules to functional nanostructured carbon by pulsed laser-induced photochemical stitching
Authors: Gokhale R. R. , Thakare V. P. , Warule S. , Lefez B. , Hannoyer B. , Jog J. P. , Ogale S. B.
Published: May 2012

A novel route employing UV laser pulses (KrF Excimer, 248 nm) to cleave small aromatic molecules and stitch the generated free radicals into functional nanostructured forms of carbon is introduced. The process differs distinctly from any strategies wherein the aromatic rings are broken in the primary process. It is demonstrated that this pulsed laser-induced photochemical stitching (PLPS) process when applied to routine laboratory solvents (or toxic chemical wastes when discarded) Chlorobenzene and o-Dichlorobenzene yields Carbon Nanospheres (CNSs) comprising of graphene-like sheets assembled in onion-like configurations. This room temperature process implemented under normal laboratory conditions is versatile and clearly applicable to the whole family of haloaromatic compounds without and with additions of precursors or other nanomaterials. We further bring out its applicability for synthesis of metal-oxide based carbon nanocomposites.
Luminance Distribution Modifies the Perceived Freshness of Strawberries
Authors: Arce-Lopera Carlos , Masuda Tomohiro , Kimura Atsushi , Wada Yuji , Okajima Katsunori
Published: May 2012

Material perception studies focus on the analysis of visual cues that may underlie the ability to distinguish between the different properties of an object. Herein, we investigated the effects of luminance distribution on the perceived freshness of a strawberry independent from its colour information. We took photographs of the degradation of a strawberry over 169 hours in a controlled environment, then presented cropped square patches of the original images to subjects who then rated the perceived freshness using a visual analogue scale. Freshness ratings were significantly highly correlated with statistical measures of the luminance and colour channels. To clarify which of these visual cues affects freshness perception, we created artificial images by modifying only the luminance distribution and keeping the colour information unchanged. The modification of luminance resulted in a highly correlated change in freshness perception, suggesting that luminance visual cues are essential to the freshness perception of strawberries. Finally, by eliminating the colour information from the images, we examined the contribution of luminance distribution independent of colour information and found that luminance information suffices for accurate estimation of strawberry freshness.
Artful Terms: A Study on Aesthetic Word Usage for Visual Art versus Film and Music
Authors: Augustin M Dorothee , Carbon Claus-Christian , Wagemans Johan
Published: May 2012

Despite the importance of the arts in human life, psychologists still know relatively little about what characterises their experience for the recipient. The current research approaches this problem by studying people's word usage in aesthetics, with a focus on three important art forms: visual art, film, and music. The starting point was a list of 77 words known to be useful to describe aesthetic impressions of visual art (Augustin et al 2012, Acta Psychologica 139 187–201). Focusing on ratings of likelihood of use, we examined to what extent word usage in aesthetic descriptions of visual art can be generalised to film and music. The results support the claim of an interplay of generality and specificity in aesthetic word usage. Terms with equal likelihood of use for all art forms included beautiful, wonderful, and terms denoting originality. Importantly, emotion-related words received higher ratings for film and music than for visual art. To our knowledge this is direct evidence that aesthetic experiences of visual art may be less affectively loaded than, for example, experiences of music. The results render important information about aesthetic word usage in the realm of the arts and may serve as a starting point to develop tailored measurement instruments for different art forms.