bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the knowledge, attitudes and practices of physicians towards obesity management in primary health care in Bahrain
Authors: Al-Ghawi Abeer , Uauy Ricardo
Published: January 2009

Aim

To examine the opinions of physicians in Bahrain regarding their role in obesity control, and to evaluate their knowledge, attitudes and practices towards obesity prevention and management in primary health care.

Design

A cross-sectional survey of physicians in Bahrain. A single-stage cluster sample was used, which included twelve health centres and 107 physicians. Ninety-seven physicians participated in the study with a 90 % response rate. A self-administered questionnaire was used to measure physicians’ knowledge and practices, their perceived role and potential limitations. Correction for design effect and finite population were considered in the analysis.

Results

The majority of physicians in Bahrain (92 %) were aware of the obesity epidemic and 60 % of them felt capable of assuming a major role in obesity control, regardless of their negative views towards the success rates of weight management. Only 36 % agreed that they had effective weight-management practices. They were knowledgeable about weight-loss goals and showed a reasonable level of obesity identification, especially as part of chronic disease care (71 %). Physicians reported a high rate of utilization of various weight-loss strategies, except for pharmacotherapy and surgery. The major barriers identified in patient care included time constraints (91 %), lack of specialty clinics (81 %), absence of guidelines (78 %) and an inadequate number of dietitians (71 %). Sixty-four per cent reported that training in lifestyle counselling and behaviour modification are important requirements.

Conclusions

Physicians in Bahrain showed a reasonable level of interest in participating in obesity prevention and management. It seems that there would be a good opportunity for better practice if physicians were supported with appropriate training and the constraints of their working environment were adequately addressed.
Gender heterogeneity in the association between lifestyles and non-fatal acute myocardial infarction
Authors: Oliveira Andreia , Barros Henrique , Lopes Carla
Published: January 2009

Objective

To evaluate the modification effect of sex in the association between lifestyles and acute myocardial infarction (AMI).

Design

Population-based case–control study. Trained interviewers collected information using a standard structured questionnaire. Associations were estimated using unconditional logistic regression. The effect modification by sex was evaluated in the regression models, testing interaction terms between lifestyles and sex.

Setting

Porto, Portugal.

Subjects

Portuguese Caucasian adults, aged ≥18 years. Cases were patients consecutively admitted with an incident AMI during 1999–2003 (n 918) and controls were a representative sample of non-institutionalized inhabitants of Porto with no evidence of previous clinical or silent infarction (n 2316).

Results

Cigarette smoking was positively associated with AMI in both men and women (smokers >15 cigarettes/d v. never smokers: OR = 9·11, 95 % CI 4·83, 17·20 for women; OR = 3·92, 95 % CI 2·75, 5·58 for men; interaction term P value = 0·001). A significant protective effect of moderate alcohol intake on AMI occurrence was found in women (0·1–15·0 g/d v. non-drinkers: OR = 0·48, 95 % CI 0·31, 0·74), but not in men. Fruit and vegetable intake, vitamin and mineral supplement use and leisure-time physical activity practice were found to decrease AMI risk, with similar effects between sexes.

Conclusions

A strong positive association between smoking and AMI was found in women. Also, a protective effect of moderate alcohol intake was only found among females. Fruit and vegetable intake, vitamin and mineral supplement use and leisure-time physical activity practice were found to decrease AMI risk in both sexes.
Effect of dietary factors on anaemia among rural elderly women in south-west China: a case–control study
Authors: Meng Liping , Liu Jun , Zhang Jian , Wang Chunrong , Man Qingqing , Li Lixiang
Published: January 2009

Objective

To investigate the possible dietary risk factors for anaemia in rural elderly women.

Design

Case–control study conducted in 2005. Cases and matched controls were interviewed in person to elicit information on lifestyle, diet and individual health. Main foods and nutrients were calculated by three 24 h recalls; intake data of tea, edible oils and spices were from an FFQ.

Setting

Fourteen villages in two counties of Guangxi Province, south-west China.

Subjects

Four hundred and twenty anaemic cases and 433 matched controls, aged 50–75 years.

Results

The mean consumption of animal foods for cases (82·4 g/d) was significantly lower than for controls (91·0 g/d), similarly for egg consumption (3·8 g/d for cases and 5·8 g/d for controls; P < 0·05). The absolute value of the Dietary Balance Index, low bound score (DBI_LBS) was significantly higher for cases than for controls (P < 0·05). Intakes of energy, protein, carbohydrate, vitamin A (retinol equivalents, RE), vitamin B1, riboflavin and Ca were significantly lower in cases than in controls (P < 0·05). There was no significant difference in Fe intake between the two groups. High intake of vitamin A (RE) was inversely associated with anaemia (quartile 4 v. quartile 1: OR = 0·6, P for linear trend = 0·02). The absolute value of DBI_LBS was positively related to anaemia (quartile 4 v. quartile 1: OR = 0·4, P for linear trend < 0·0001).

Conclusion

For rural elderly women in south-west China, anaemia had a strong positive association with undernutrition and a negative association with vitamin A intake. Dietary Fe intake was not found to be an independent risk factor for anaemia.
Adolescent dietary patterns are associated with lifestyle and family psycho-social factors
Authors: Ambrosini Gina L , Oddy Wendy H , Robinson Monique , O’Sullivan Therese A , Hands Beth P , de Klerk Nick H , Silburn Sven R , Zubrick Stephen R , Kendall Garth E , Stanley Fiona J , Beilin Lawrence J
Published: January 2009

Objective

Dietary intake during adolescence contributes to lifelong eating habits and the development of early risk factors for disease in adulthood. Few studies have examined the dietary patterns of adolescents and the social and environmental factors that may affect them during this life stage. The present study describes dietary patterns in a cohort of adolescents and examines their associations with socio-economic factors, as well as parental and adolescent risk factor behaviours.

Design

A semi-quantitative FFQ was used to assess study adolescents’ usual dietary intake over the previous year. Information was collected on family functioning and various socio-economic and risk factor variables via questionnaire. Adolescents visited the study clinic for anthropometric measurements.

Setting

The Western Australian Pregnancy Cohort Study (Raine Study), Perth, Western Australia.

Subjects

Adolescents (n 1631) aged 14 years from a pregnancy cohort study.

Results

Factor analysis identified two distinct dietary patterns that differed predominantly in fat and sugar intakes. The ‘Western’ pattern consisted of high intakes of take-away foods, soft drinks, confectionery, French fries, refined grains, full-fat dairy products and processed meats. The ‘healthy’ pattern included high intakes of whole grains, fruit, vegetables, legumes and fish. ANOVA showed that the ‘Western’ dietary pattern was positively associated with greater television viewing and having a parent who smoked, and was inversely associated with family income. The ‘healthy’ pattern was positively associated with female gender, greater maternal education, better family functioning and being in a two-parent family, and was inversely associated with television viewing.

Conclusions

The study suggests that both lifestyle factors and family psycho-social environment are related to dietary patterns in Australian adolescents.
A randomized behavioural trial targeting glycaemic index improves dietary, weight and metabolic outcomes in patients with type 2 diabetes
Authors: Gutschall Melissa Davis , Miller Carla K , Mitchell Diane C , Lawrence Frank R
Published: January 2009

Objective

Glycaemic index (GI) reflects the postprandial glucose response of carbohydrate-containing foods. A diet with lower GI may improve glycaemic control in people with diabetes. The purpose of the present study was to evaluate the change in outcomes following a behavioural intervention which promoted lower-GI foods among adults with diabetes.

Design

A pre-test–post-test control group design was used with participants randomly assigned to an immediate (experimental) or delayed (control) treatment group. The intervention included a 9-week, group-based intervention about carbohydrate and the glycaemic index. Dietary, anthropometric and metabolic measures were obtained pre/post-intervention in both groups and at 18-week follow-up for the immediate group.

Setting

The study was conducted in a rural community in the north-eastern USA.

Subjects

Adults having type 2 diabetes mellitus for ≥1 year, aged 40–70 years and not requiring insulin therapy (n 109) were recruited.

Results

Following the intervention, mean dietary GI (P < 0·001), percentage of energy from total fat (P < 0·01) and total dietary fibre (P < 0·01) improved in the immediate compared with the delayed group. Mean BMI (P < 0·0001), fasting plasma glucose (P = 0·03), postprandial glucose (P = 0·02), fructosamine (P = 0·02) and insulin sensitivity factor (P = 0·04) also improved in the immediate group compared with the delayed group. Mean waist circumference among males (P < 0·01) and body weight among males and females (P < 0·01) were significantly different between treatment groups.

Conclusions

Educating clients about carbohydrate and the glycaemic index can improve dietary intake and health outcomes among adults with type 2 diabetes.
Psychopathological Correlates and Psychometric Properties of the White Bear Suppression Inventory in a Turkish Sample
Authors: Altın Müjgan , Gençöz Tülin
Published: January 2009

This study examined the psychometric properties of the White Bear Suppression Inventory (WBSI) in a sample of 273 Turkish undergraduate students. The WBSI assesses people’s tendency toward thought suppression. The reliability and validity analyses of the Turkish version of the scale indicated that the WBSI had adequate psychometric properties in a Turkish sample. Internal consistency, and split-half and test-retest reliability coefficients were satisfactory. Consistent with the original WBSI, factor analysis of the scale identified a single component that accounted for 43.3% of the total variance. Concurrent validity of the Turkish version indicated that the scale exhibited significantly positive correlations with obsessive-compulsive, depression, and trait anxiety symptoms, as well as with responsibility attitudes, and thought-action fusion biases. All these findings supported the cross-cultural validity of WBSI.
Students’ Conceptions of Assessment
Authors: Hirschfeld Gerrit H.F. , Brown Gavin T.L.
Published: January 2009

Demonstrating factor invariance across population characteristics is an important facet of validating instruments. A new instrument to examine students’ conceptions of assessment (SCoA) has been demonstrated in studies to show significant relations to secondary school students’ academic performance in mathematics and reading. The research reported here investigates the stability of the factor structure and structural relationships to achievement in reading comprehension across student sex, year-level, and ethnicity. Multiple group confirmatory factor analysis found, in a sample of 3,506 students, that the factor structure of the SCoA was invariant. Conversely, statistically significant differences for sex, year, and ethnicity were found for how the conceptions of assessment related to academic performance in reading. These differences between the structural models may not indicate a deficiency in the instrument but, rather, sensitivity to real-world differences among subgroups. The structural differences can be understood in terms of sex differences in approaches to learning, year differences in participation in the New Zealand national qualifications assessment system, and ethnic differences in experience of bias and prejudice in schooling.
Assessing Rational and Intuitive Thinking Styles
Authors: Witteman Cilia , van den Bercken John , Claes Laurence , Godoy Antonio
Published: January 2009

Theories of dual cognition assume two distinguishable information processing styles: rational and intuitive. We discuss how the concepts of rationality and intuition are used in these theories, and the relations of these two thinking styles to personality characteristics. With the Rational-Experiential Inventory (REI; Pacini & Epstein, 1999 ), a questionnaire that assesses personal preferences for thinking either rationally or intuitively, we found clear evidence for the independence of the two thinking styles in a large Dutch sample (N = 774). We also found Conscientiousness to be a significant predictor of a preference for rational thinking and an inverse predictor of intuitive thinking. We also administered the REI and a Big Five inventory to a Spanish sample (N = 141), and present these results next to those of the Dutch sample. We further established the validity of the REI’s distinction between rationality and intuition by administering another measure, the Preference for Intuition or Deliberation (PID; Betsch, 2004 , 2008 ), to a subset of the Dutch sample (n = 405). We briefly describe two small studies in which a preference for rationality or intuition, measured by the REI, was found to be related to task behavior. In the general discussion we consider all results together, and compare them to Pacini and Epstein’s results. We conclude that a dual-process distinction between rationality and intuition is valid cross-culturally and that a proclivity toward either is reliably measured by the REI, not only in the USA but in Europe as well.
A unifying framework for shoreline migration: 2. Application to wave‐dominated coasts
Authors: Wolinsky Matthew A. , Murray A. Brad
Published: January 2009

The Bruun rule, widely used to predict transgression due to sea level rise on decade to century timescales based on a fixed nearshore profile, neglects the influence of inland topography and substrate lithology, leading to physically unreasonable predictions on longer timescales. We use a new approach, the shoreline Exner equation, to model shoreline transgression on wave‐dominated coasts over timescales of decades to millennia. Our results show that interactions between nearshore processes and inland topography, neglected by Bruun‐style models, drive morphologic evolution which modulates shoreline retreat. Analytical solutions suggest that while short‐term shoreline retreat will sometimes follow the Bruun rule, long‐term transgression will always follow the slope of the inland topography. Moreover, our results show that the slope of the inland landscape, relative to the nearshore slope, exerts a first‐order control on coastal morphology, such that steep coasts tend to form cliff‐backed beaches while gentle coasts tend to form barrier island‐lagoon systems. However compositional variations between the inland landscape and nearshore system can alter this pattern.
Carbon dioxide induced stomatal closure increases radiative forcing via a rapid reduction in low cloud
Authors: Doutriaux‐Boucher M. , Webb M. J. , Gregory J. M. , Boucher O.
Published: January 2009

We performed an ensemble of twelve five‐year experiments using a coupled climate‐carbon‐cycle model with scenarios of prescribed atmospheric carbon dioxide concentration; CO2 was instantaneously doubled or quadrupled at the start of the experiments. Within these five years, climate feedback is not significantly influenced by the effects of climate change on the carbon system. However, rapid changes take place, within much less than a year, due to the physiological effect of CO2 on plant stomatal conductance, leading to adjustment in the shortwave cloud radiative effect over land, due to a reduction in low cloud cover. This causes a 10% enhancement to the radiative forcing due to CO2, which leads to an increase in the equilibrium warming of 0.4 and 0.7 K for doubling and quadrupling. The implications for calibration of energy‐balance models are discussed.
STEREO observations of shock formation in the solar wind
Authors: Russell C. T. , Jian L. K. , Blanco Cano X. , Luhmann J. G. , Zhang T. L.
Published: January 2009

During solar minimum, the majority of shocks observed at 1 AU are associated with interactions between fast and slow streams, appearing as the pressure ridge between the streams narrows, and as the fast mode speed becomes smaller than the velocity jump between streams. Shocks are believed to strengthen when following shock waves catch up with the leading shock. STEREO observations confirm this behavior for very weak shocks. We can also put limits on the location of the shock‐forming region by examining the periods of alignment between Venus and STEREO. In a period in which we see nine shocks at 1 AU, we see no shocks at 0.72 AU. Hence, stream interactions from 0.72 AU to 1 AU are responsible for the development of most of the shocks observed at 1 AU during solar minimum.
Two‐dimensional nonlinear dynamics of bidirectional beam‐plasma instability
Authors: Pavan J. , Ziebell L. F. , Gaelzer R. , Yoon P. H.
Published: January 2009

Solar wind electrons near 1 AU feature wide‐ranging asymmetries in the superthermal tail distribution. Gaelzer et al. (2008) recently demonstrated that a wide variety of asymmetric distributions results if one considers a pair of counterstreaming electron beams interacting with the core solar wind electrons. However, the nonlinear dynamics was investigated under the simplifying assumption of one dimensionality. In the present paper, this problem is revisited by extending the analysis to two dimensions. The classic bump‐on‐tail instability involves a single electron beam interacting with the background population. The bidirectional or counterstreaming beams excite Langmuir turbulence initially propagating in opposite directions. It is found that the nonlinear mode coupling leads to the redistribution of wave moments along concentric arcs in wave number space, somewhat similar to the earlier findings by Ziebell et al. (2008) in the case of one beam‐plasma instability. However, the present result also shows distinctive features. The similarities and differences in the nonlinear wave dynamics are discussed. It is also found that the initial bidirectional beams undergo plateau formation and broadening in perpendicular velocity space. However, the anisotropy persists in the nonlinear stage, implying that an additional pitch angle scattering by transverse electromagnetic fluctuations is necessary in order to bring the system to a truly isotropic state.
Segmentation of megathrust rupture zones from fore‐arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile
Authors: Melnick Daniel , Bookhagen Bodo , Strecker Manfred R. , Echtler Helmut P.
Published: January 2009

This work explores the control of fore‐arc structure on segmentation of megathrust earthquake ruptures using coastal geomorphic markers. The Arauco‐Nahuelbuta region at the south‐central Chile margin constitutes an anomalous fore‐arc sector in terms of topography, geology, and exhumation, located within the overlap between the Concepción and Valdivia megathrust segments. This boundary, however, is only based on ∼500 years of historical records. We integrate deformed marine terraces dated by cosmogenic nuclides, syntectonic sediments, published fission track data, seismic reflection profiles, and microseismicity to analyze this earthquake boundary over 102–106years. Rapid exhumation of Nahuelbuta's dome‐like core started at 4 ± 1.2 Ma, coeval with inversion of the adjacent Arauco basin resulting in emergence of the Arauco peninsula. Here, similarities between topography, spatiotemporal trends in fission track ages, Pliocene‐Pleistocene growth strata, and folded marine terraces suggest that margin‐parallel shortening has dominated since Pliocene time. This shortening likely results from translation of a fore‐arc sliver or microplate, decoupled from South America by an intra‐arc strike‐slip fault. Microplate collision against a buttress leads to localized uplift at Arauco accrued by deep‐seated reverse faults, as well as incipient oroclinal bending. The extent of the Valdivia segment, which ruptured last in 1960 with anMw9.5 event, equals the inferred microplate. We propose that mechanical homogeneity of the fore‐arc microplate delimits the Valdivia segment and that a marked discontinuity in the continental basement at Arauco acts as an inhomogeneous barrier controlling nucleation and propagation of 1960‐type ruptures. As microplate‐related deformation occurs since the Pliocene, we propose that this earthquake boundary and the extent of the Valdivia segment are spatially stable seismotectonic features at million year scale.
Response of the middle atmosphere to the 11‐year solar cycle simulated with the Whole Atmosphere Community Climate Model
Authors: Tsutsui J. , Nishizawa K. , Sassi F.
Published: January 2009

A long‐term numerical experiment has been conducted using the Whole Atmosphere Community Climate Model (WACCM) to investigate the response of the middle atmosphere to time‐varying spectral solar irradiance over multiple 11‐year cycles, modeled on the basis of observed 10.7‐cm radio flux (F10.7). The model domain covers from the Earth's surface to the lower thermosphere with approximately two‐degree horizontal resolution and 66 vertical layers. Sea surface temperatures are prescribed by a climatological annual cycle, and boundary data for chemical compositions are held constant. The experiment does not include spontaneous nor imposed quasi‐biennial oscillation. Temperature and ozone differences near the stratopause between solar max and min, typically 0.8 K and 1.6% corresponding to approximately 100 units of F10.7 variation, have general agreement with the current scientific understanding. The model's dynamical responses as an indirect solar effect are substantially weak during winter against evidences from past empirical studies. The indirect solar signal tends to appear when the polar vortex becomes weak. The most striking signal is more frequent stratospheric sudden warmings during solar max in the Northern Hemisphere late winter through early spring, supporting observed tendencies. This modulation has an aspect of the annular mode and results in a major impact on the troposphere in early spring. Such a signal, however, does not appear in the Southern Hemisphere where the model has a westerly bias. There is no marked response in the equatorial lower stratosphere.
Acidic processing of mineral dust iron by anthropogenic compounds over the north Pacific Ocean
Authors: Solmon F. , Chuang P. Y. , Meskhidze N. , Chen Y.
Published: January 2009

Atmospheric processing of mineral aerosol by anthropogenic pollutants may be an important process by which insoluble iron can be transformed into soluble forms and become available to oceanic biota. Observations of the soluble iron fraction in atmospheric aerosol exhibit large variability, which is poorly represented in models. In this study, we implemented a dust iron dissolution scheme in a global chemistry transport model (GEOS‐Chem). The model is applied over the North Pacific Ocean during April 2001, a period when concentrations of dust and pollution within the east Asia outflow were high. Simulated fields of many key chemical constituents compare reasonably well with available observations, although some discrepancies are identified and discussed. In our simulations, the production of soluble iron varies temporally and regionally depending on pollution‐to‐dust ratio, primarily due to strong buffering by calcite. Overall, we show that the chemical processing mechanism produces significant amounts of dissolved iron reaching and being deposited in remote regions of the Pacific basin, with some seasonal variability. Simulated enhancements in particulate soluble iron fraction range from 0.5% to 6%, which is consistent with the observations. According to our simulations, ∼30% to 70% of particulate soluble iron over the North Pacific Ocean basin can be attributed to atmospheric processing. On the basis of April 2001 monthly simulations, sensitivity tests suggest that doubling SO2 emissions can induce a significant increase (13% on average, up to 40% during specific events) in dissolved iron production and deposition to the remote Pacific. We roughly estimate that half of the primary productivity induced by iron deposition in a north Pacific high‐nutrient low‐chlorophyll region is due to soluble iron derived from anthropogenic chemical processing of Asian aerosol.
Crystal structure of CbpF, a bifunctional choline‐binding protein and autolysis regulator from Streptococcus pneumoniae
Authors: Molina Rafael , González Ana , Stelter Meike , Pérez‐Dorado Inmaculada , Kahn Richard , Morales María , Campuzano Susana , Campillo Nuria E , Mobashery Shahriar , García José L , García Pedro , Hermoso Juan A
Published: January 2009

Phosphorylcholine, a crucial component of the pneumococcal cell wall, is essential in bacterial physiology and in human pathogenesis because it binds to serum components of the immune system and acts as a docking station for the family of surface choline‐binding proteins. The three‐dimensional structure of choline‐binding protein F (CbpF), one of the most abundant proteins in the pneumococcal cell wall, has been solved in complex with choline. CbpF shows a new modular structure composed both of consensus and non‐consensus choline‐binding repeats, distributed along its length, which markedly alter its shape, charge distribution and binding ability, and organizing the protein into two well‐defined modules. The carboxy‐terminal module is involved in cell wall binding and the amino‐terminal module is crucial for inhibition of the autolytic LytC muramidase, providing a regulatory function for pneumococcal autolysis.
Retroviral integrase superfamily: the structural perspective
Authors: Nowotny Marcin
Published: January 2009

The retroviral integrase superfamily (RISF) comprises numerous important nucleic acid‐processing enzymes, including transposases, integrases and various nucleases. These enzymes are involved in a wide range of processes such as transposition, replication and repair of DNA, homologous recombination, and RNA‐mediated gene silencing. Two out of the four enzymes that are encoded by the human immunodeficiency virus—RNase H1 and integrase—are members of this superfamily. RISF enzymes act on various substrates, and yet show remarkable mechanistic and structural similarities. All share a common fold of the catalytic core and the active site, which is composed primarily of carboxylate residues. Here, I present RISF proteins from a structural perspective, describing the individual members and the common and divergent elements of their structures, as well as the mechanistic insights gained from the structures of RNase H1 enzyme complexes with RNA/DNA hybrids.
Origin of surface potential change during ferroelectric switching in epitaxial PbTiO3 thin films studied by scanning force microscopy
Authors: Kim Yunseok , Bae Changdeuck , Ryu Kyunghee , Ko Hyoungsoo , Kim Yong Kwan , Hong Seungbum , Shin Hyunjung
Published: January 2009

We investigated the surface potential of the ferroelectric domains of the epitaxial PbTiO3 (PTO) films using both Kelvin probe and piezoresponse force microscopy. The surface potential changes as a function of applied biases suggested that the amount and sign of surface potentials depend on the correlation between polarization and screen charges. It also suggested that the trapped negative charges exist on the as-deposited PTO surfaces. Injected charges and their resultant surface potentials are investigated by grounded tip scans. The results unveiled the origin of surface potential changes during ferroelectric switching in the epitaxial PTO films.
Origin of electric field distribution in organic field-effect transistor: Experiment and analysis
Authors: Weis Martin , Manaka Takaaki , Iwamoto Mitsumasa
Published: January 2009

Electric field distribution in the pentacene organic field-effect transistor (OFET) channel is investigated using the microscopic optical second-harmonic generation (SHG). At the on- and off-states of the OFET, enhanced SHG signal was observed near the drain electrode and at the source and drain electrodes. Our analytical analysis indicates that the Laplace field formation is in the off-state of the OFET. The electric field profile in the on-state representing distribution by the space-charge formation in the channel due to injected carriers was calculated by the transmission line model. Theoretical models are confirmed by the experimental results and the result shows that pentacene can be used as a dielectric material. On the basis of estimated potential distribution in the on-state, a model for the evaluation of the drain-source current is proposed.
Mode-specific photoionization dynamics of a simple asymmetric target: OCS
Authors: Das Aloke , Poliakoff E. D. , Lucchese R. R. , Bozek John D.
Published: January 2009

Vibrationally resolved photoelectron spectra of OCS+(C Σ2+) are used to probe coupling between photoelectron motion and molecular vibration for a simple asymmetric system. Spectra are reported over the photon energy range of 21≤hν≤55 eV. Vibrational branching ratios for all of the normal modes are determined and the results exhibit mode-specific deviations from Franck–Condon behavior. Schwinger variational calculations indicate the presence of four shape resonances, two kσ resonances and two kπ resonances. All of the resonances play a role in the observed vibrationally resolved behavior. Two results are striking; first, the resonances are more sensitive to the C–O stretch than to the C–S stretch, particularly for photon energies above 30 eV. This relative insensitivity of the resonance to geometry changes involving a third-row element is similar to other systems studied. Second, theoretical results lead to the counterintuitive conclusion that bending the molecule suppresses the high energy resonance, even though there is an enhancement in the vibrational branching ratio curve for the single quantum bending excitation. The agreement between the theoretical and experimental branching ratio curves is good. Finally, the results unambiguously demonstrate that the forbidden bending excitation is caused by photoelectron-mediated vibronic coupling, i.e., the variation in the electronic transition matrix element with geometry, rather than the traditional explanation of interchannel vibronic coupling with intensity borrowing between ionic states.
Determination of the structure of adenine monolayers adsorbed at Au(110)/electrolyte interfaces using reflection anisotropy spectroscopy
Authors: Smith C. I. , Bowfield A. , Dolan G. J. , Cuquerella M. C. , Mansley C. P. , Fernig D. G. , Edwards C. , Weightman P.
Published: January 2009

Reflection anisotropy spectroscopy (RAS) has been used to show that at saturation coverage adenine adsorbs on the Au(110)/electrolyte interface in a base-stacking configuration with the plane of the bases orientated vertically on the surface and with the long axis of the molecules parallel to the [11¯0] direction. Changes in the RAS observed from adsorbed adenine as a result of changes in the potential applied to the Au(110) electrode could arise from slight changes in the orientation of the molecules in the vertical plane.
Hierarchy of adhesion forces in patterns of photoreactive surface layers
Authors: Hlawacek Gregor , Shen Quan , Teichert Christian , Lex Alexandra , Trimmel Gregor , Kern Wolfgang
Published: January 2009

Precise control of surface properties including electrical characteristics, wettability, and friction is a prerequisite for manufacturing modern organic electronic devices. The successful combination of bottom up approaches for aligning and orienting the molecules and top down techniques to structure the substrate on the nano- and micrometer scale allows the cost efficient fabrication and integration of future organic light emitting diodes and organic thin film transistors. One possibility for the top down patterning of a surface is to utilize different surface free energies or wetting properties of a functional group. Here, we used friction force microscopy (FFM) to reveal chemical patterns inscribed by a photolithographic process into a photosensitive surface layer. FFM allowed the simultaneous visualization of at least three different chemical surface terminations. The underlying mechanism is related to changes in the chemical interaction between probe and film surface.
Multimode waveguide evanescent field fluorescence microscopy: Measurement of cell-substratum separation distance
Authors: Hassanzadeh Abdollah , Armstrong Souzan , Dixon S. Jeffrey , Mittler Silvia
Published: January 2009

Waveguide evanescent field fluorescence microscopy allows imaging of thin films and contact regions between biological cells and their substratum. On changing the propagating waveguide mode exciting the fluorescence markers, the normalized evanescent field intensity at a specific distance from the waveguide surface is modified. This enables the determination of thin film thickness and cell-substratum separation distances. An extensive analysis of multimode ion-exchanged waveguides is presented, focusing on their applications as substrata for studying interfacial phenomena. The experimental results on Langmuir–Blodgett films are in excellent agreement with the simulations. For osteoblastic cells, close contacts were observed.
Stability of protein-decorated mixed lipid membranes: The interplay of lipid-lipid, lipid-protein, and protein-protein interactions
Authors: Loew Stephan , Hinderliter Anne , May Sylvio
Published: January 2009

Membrane-associated proteins are likely to contribute to the regulation of the phase behavior of mixed lipid membranes. To gain insight into the underlying mechanism, we study a thermodynamic model for the stability of a protein-decorated binary lipid layer. Here, proteins interact preferentially with one lipid species and thus locally sequester that species. We aim to specify conditions that lead to an additional macroscopic phase separation of the protein-decorated lipid membrane. Our model is based on a standard mean-field lattice-gas description for both the lipid mixture and the adsorbed protein layer. Besides accounting for the lipid-protein binding strength, we also include attractive lipid-lipid and protein-protein interactions. Our analysis characterizes the decrease in the membrane’s critical interaction parameter as a function of the lipid-protein binding strength. For small and large binding strengths we provide analytical expressions; numerical results cover the intermediate range. Our results reiterate the crucial importance of the line tension associated with protein-induced compositional gradients and the presence of attractive lipid-lipid interactions within the membrane. Direct protein-protein attraction effectively increases the line tension and thus tends to further destabilize the membrane.
Solvent effects on resonance Raman and hyper-Raman scatterings for a centrosymmetric distyrylbenzene and relationship to two-photon absorption
Authors: Leng Weinan , Bazan Guillermo C. , Kelley Anne Myers
Published: January 2009

Resonance Raman (RR) and resonance hyper-Raman (RHR) spectra have been obtained for a nominally centrosymmetric dialkylammonium-substituted distyrylbenzene that was previously shown to exhibit a strong solvent polarity effect on its two-photon absorption strength. Spectra have been obtained in acetonitrile, methanol, dimethylsulfoxide, and water. In each solvent, the RR and RHR spectra show very similar intensity patterns in the strongest lines in both the C=C and C–C stretching regions, but the RHR peaks are shifted to higher energies by 5–10 cm−1. These are interpreted as vibrations of similar mode character but different symmetries, with u symmetry modes observed in RHR and g symmetry modes in RR. In all solvents the nonzero chromophore contribution to the hyper-Rayleigh scattering indicates that the center of symmetry is broken to some degree, and this effect is more pronounced in water than in the other three solvents. The ratio of RR intensity to one-photon fluorescence intensity shows an approximate inverse relationship with the fluorescence quantum yield, consistent with the approximate solvent independence of the one-photon transition strength implied by the linear absorption spectra. The ratio of RHR intensity to two-photon fluorescence intensity is smaller than the corresponding RR to one-photon fluorescence ratio in all four solvents.
Thermodynamics of ternary electrolytes: Enhanced adsorption of macroions as minority component to liquid interfaces
Authors: Kung William , Solis Francisco J. , Olvera de la Cruz Monica
Published: January 2009

We study the equilibrium thermodynamics between two ternary ionic systems in immiscible solvents characterized by different dielectric constants. We consider system geometries wherein the two phases of immiscible solvents occupy, respectively, semi-infinite regions of space separated by neutral and charged planar interfaces. Specifically we analyze the case where the ternary system is composed of a pair of symmetric ions plus a minority charged component of high valence. We describe the system by means of a nonlinear mean-field theory. We first obtain exact analytical solutions for the electrostatic potentials, as well as density profiles for a symmetric binary system, and then extend these results to the ternary case using the perturbation theory. We show that the corresponding adsorption and depletion of multivalent macroions at the interface are highly enhanced when compared with the monovalent case.
Dielectric, piezoelectric, and electromechanical properties of morphotropic phase boundary compositions in the Pb(Mg1/3Ta2/3)O3–PbZrO3–PbTiO3 ternary system
Authors: Hao Hua , Zhang Shujun , Liu Hanxing , Shrout Thomas R.
Published: January 2009

Morphotropic phase boundary (MPB) compositions, separating the rhombohedral and tetragonal phases within the Pb(Mg1/3Ta2/3)O3–PbZrO3–PbTiO3 (PMT-PZ-PT) ternary system, were identified using x-ray diffraction and confirmed by their dielectric and piezoelectric properties. Optimal properties were found for the MPB composition of 0.4PMT-0.2PZ-0.4PT, with a dielectric constant εr and a piezoelectric coefficient (d33) of the order of 4000 and 580 pC/N, respectively. The planar and thickness electromechanical coupling factors were found to be kp=57.2% and kt=44.4%, with a moderate Curie temperature of 175 °C. Compositions with increasing PMT content (>0.3) exhibited relaxorlike characteristics, showing dispersive dielectric behavior with respect to frequency, indicative of the decay of the macrodomain state to microdomain state.
Controllable p-type doping of GaAs nanowires during vapor-liquid-solid growth
Authors: Gutsche Christoph , Regolin Ingo , Blekker Kai , Lysov Andrey , Prost Werner , Tegude Franz J.
Published: January 2009

We report on controlled p-type doping of GaAs nanowires grown by metal-organic vapor-phase epitaxy on (111)B GaAs substrates using the vapor-liquid-solid growth mode. p-type doping of GaAs nanowires was realized by an additional diethyl zinc flow during the growth. Compared to nominally undoped structures, the current increases by more than six orders of magnitude. The transfer characteristics of fabricated nanowire metal-insulator-semiconductor field-effect transistor devices proved p-type conductivity. By adjusting the II/III ratio, controlled doping concentrations from 4.6×1018 up to 2.3×1019 cm−3 could be achieved at a growth temperature of 400 °C. The doping concentrations were estimated from electrical conductivity measurements applied to single nanowires with different diameters. This estimation is based on a mobility versus carrier concentration model with surface depletion included.
Structural, magnetic, and magnetotransport studies in bulk Ni55.2Mn18.1Ga26.7 alloy
Authors: Ingale Babita , Gopalan R. , Chandrasekaran V. , Ram S.
Published: January 2009

Structural, magnetic, and transport properties have been investigated in off-stochiometric bulk Ni55.2Mn18.1Ga26.7 alloy. The alloy undergoes an austenite-martensite phase transition in ferromagnetic state at 264 K. The temperature and field dependence of electrical resistivity studies revealed that the electron-electron scattering is dominant in determining the resistivity below 80 K, while at higher temperatures (80–300 K), electron-magnon as well as electron-phonon scattering dominate. A negative magnetoresistance value of 7% maximum near TC (∼283 K) at 7 T field has been obtained in the alloy. Also a magnetocaloric value (ΔSM) of −1.3 J/kg K has been observed at around 264 K.
Transverse wall dynamics in a spin valve nanostrip
Authors: Ndjaka J. M. B. , Thiaville A. , Miltat J.
Published: January 2009

The magnetism of a Fe20Ni80/Cu/Co spin valve, in which a layer of FeNi containing a head-to-head transverse domain wall is coupled to a uniformly magnetized Co layer, via a nonmagnetic Cu layer, was investigated by micromagnetics (mainly numerical simulations). In equilibrium, due to the magnetostatic coupling between the layers, a quasiwall is created in the Co layer, which affects the domain wall profile in the FeNi layer. The dynamics of the domain wall under an applied field is also modified, and two opposite effects due to the spin valve geometry have been found, resulting, on the one hand, from the variation in the width of the domain wall and, on the other hand, from the additional damping of magnetization dynamics due to the cobalt layer.
Magnetostatic bias in multilayer microwires: Theory and experiments
Authors: Escrig J. , Allende S. , Altbir D. , Bahiana M. , Torrejón J. , Badini G. , Vázquez M.
Published: January 2009

The hysteresis curves of multilayer microwires consisting of a soft magnetic nucleus, intermediate nonmagnetic layers, and an external hard magnetic layer are investigated. The magnetostatic interaction between magnetic layers is proved to give rise to an antiferromagneticlike coupling resulting in a magnetostatic bias in the hysteresis curves of the soft nucleus. This magnetostatic biasing effect is investigated in terms of the microwire geometry. The experimental results are interpreted considering an analytical model taking into account the magnetostatic interaction between the magnetic layers.
Confinement factor and absorption loss of AlInGaN based laser diodes emitting from ultraviolet to green
Authors: Zhang L. Q. , Jiang D. S. , Zhu J. J. , Zhao D. G. , Liu Z. S. , Zhang S. M. , Yang H.
Published: January 2009

Confinement factor and absorption loss of AlInGaN based multiquantum well laser diodes (LDs) were investigated by numerical simulation based on a two-dimensional waveguide model. The simulation results indicate that an increased ridge height of the waveguide structure can enhance the lateral optical confinement and reduce the threshold current. For 405 nm violet LDs, the effects of p-AlGaN cladding layer composition and thickness on confinement factor and absorption loss were analyzed. The experimental results are in good agreement with the simulation analysis. Compared to violet LD, the confinement factors of 450 nm blue LD and 530 nm green LD were much lower. Using InGaN as waveguide layers that has higher refractive index than GaN will effectively enhance the optical confinement for blue and green LDs. The LDs based on nonpolar substrate allow for thick well layers and will increase the confinement factor several times. Furthermore, the confinement factor is less sensitive to alloys composition of waveguide and cladding layers, being an advantage especially important for ultraviolet and green LDs.
Magnetic hyperthermia in single-domain monodisperse FeCo nanoparticles: Evidences for Stoner–Wohlfarth behavior and large losses
Authors: Lacroix L.-M. , Malaki R. Bel , Carrey J. , Lachaize S. , Respaud M. , Goya G. F. , Chaudret B.
Published: January 2009

We report on hyperthermia measurements on a colloidal solution of 14.2±1.5 nm monodisperse FeCo nanoparticles (NPs). Losses as a function of the magnetic field display a sharp increase followed by a plateau, which is what is expected for losses of ferromagnetic single-domain NPs. The frequency dependence of the coercive field is deduced from hyperthermia measurement and is in quantitative agreement with a simple model of noninteracting NPs. The measured losses (1.5 mJ/g) compare to the highest of the literature, although the saturation magnetization of the NPs is well below the bulk one.
Automated differentiation of curly and silver birch by ultrasound attenuation
Authors: Salmi Ari , Hintikka Tuomas , Karppinen Timo , Forsman Pia , Hæggström Edward
Published: January 2009

We present a method for field use to differentiate a natural mutation, curly birch (CB) (Betula pendula var carelica Sok.) from the ordinary silver birch (SB) (Betula pendula Roth.). Differentiating the two types is crucial for forest owners, since CB commands a high price, and the faster-growing SBs overshadow these trees. This creates a need for an automated, easily applicable method to differentiate between them. The presented device segregates intact trunks by recording the attenuation of 100 kHz ultrasonic longitudinal tone bursts launched radially through the trunks. We achieved 90% probability of correct characterization (0% probability of false positive) for 20 trunks.
Dislocation-governed current-transport mechanism in (Ni/Au)–AlGaN/AlN/GaN heterostructures
Authors: Arslan Engin , Altındal Şemsettin , Özçelik Süleyman , Ozbay Ekmel
Published: January 2009

The current-transport mechanisms in (Ni/Au)–Al0,22Ga0,78N/AlN/GaN heterostructures were studied by using temperature dependent forward-bias current-voltage (I-V) characteristics in the temperature range of 80–410 K. In order to determine the current mechanisms for (Ni/Au)–Al0,22Ga0,78N/AlN/GaN heterostructures, we fitted the experimental I-V data to the analytical expressions given for the current-transport mechanisms in a wide range of applied biases and at different temperatures. The contributions of thermionic-emission, generation-recombination, tunneling, leakage currents that are caused by inhomogeneities, and defects at the metal-semiconductor interface current mechanisms were all taken into account. The best fitting results were obtained for the tunneling current mechanism. On the other hand, we did not observe sufficient agreement between the experimental data and the other current mechanisms. The temperature dependencies of the tunneling saturation current (It) and tunneling parameters (E0) were obtained from fitting results. We observed a weak temperature dependence of the saturation current and the absence of the temperature dependence of the tunneling parameters in this temperature range. The results indicate that in the temperature range of 80–410 K, the mechanism of charge transport in the (Ni/Au)−Al0.22Ga0.78N/AlN/GaN heterostructure is performed by tunneling among those dislocations intersecting the space charge region. The dislocation density (D) that was calculated from the I-V characteristics, according to a model of tunneling along the dislocation line, gives the value of 0.24×107 cm−2. This value is close in magnitude to the dislocation density that was obtained from the x-ray diffraction measurements.