Roughening kinetics of reactively sputter-deposited Ti-Al-N films on Si(100)

The roughening kinetics of Ti_{1? x} Al _x N (0?x? 1) films 600 nm thick synthesized by reactive dc magnetron sputtering on Si(100) substrates has been investigated by atomic force microscopy (AFM). The quantification of surface roughening was achieved by calculation of both vertical root-mean-square roughness and lateral correlation lengths of the film surface using the height-height correction functions of measured AFM images. For all the Ti_{1? x} Al _x N films, a steady roughness exponent α = 0.94 ± 0.03 was determined. The evolution of the surface topography as a function of Al concentration is discussed in terms of the competition between surface diffusion and shadowing instability during sputter deposition.     

Vacancy trapping on lattices with different coordination numbers

Abstract

The kinetics of disorder→order transformations in alloys have been studied by Monte Carlo simulations. These simulations employed a vacancy diffusion mechanism, and were set on lattices having different coordination numbers, z. At low temperatures, the vacancy mobility is dominated by processes in which the vacancy becomes confined to local atomic arrangements that serve as vacancy traps. The scaling with z of the ordering kinetics can be interpreted in terms of the strengths and probabilities of vacancy traps on the different lattices.     

Low-energy boron implants into silicon: A molecular dynamics simulation study of implants into a stepped surface

Molecular dynamics simulations have been conducted to study implantation of boron with a low kinetic energy (E _k in the range 5 eV) into the silicon surface. The bombarded surface has a realistic stepped structure and the geometry of the step edge is taken from the theory of Chadi (1987, Phys. Rev. Lett., 59, 1691). It is found that reflection is the more common event. However subsurface implants and adatom formations are also observed. The effect of the step morphology is important and different trajectories are observed if the ions hit steps of different shapes.     

Initial sintering of cylindrical particles of different sizes by surface diffusion

Sintering of two cylindrical particles of different sizes by surface diffusion at the early stage is theoretically analysed. Formulae for the neck growth rate are derived using a variational principle and the continuity equation of vacancies. The size difference between two particles is found to influence the growth rate of the neck only when the difference is large.     

Investigating the Performance of Alternate Regression Weights by Studying All Possible Criteria in Regression Models with a Fixed Set of Predictors

We describe methods for assessing all possible criteria (i.e., dependent variables) and subsets of criteria for regression models with a fixed set of predictors, x (where x is an n×1 vector of independent variables). Our methods build upon the geometry of regression coefficients (hereafter called regression weights) in n-dimensional space. For a full-rank predictor correlation matrix, R _xx, of order n, and for regression models with constant R ² (coefficient of determination), the OLS weight vectors for all possible criteria terminate on the surface of an n-dimensional ellipsoid. The population performance of alternate regression weights—such as equal weights, correlation weights, or rounded weights—can be modeled as a function of the Cartesian coordinates of the ellipsoid. These geometrical notions can be easily extended to assess the sampling performance of alternate regression weights in models with either fixed or random predictors and for models with any value of R ². To illustrate these ideas, we describe algorithms and R (R Development Core Team, 2009) code for: (1) generating points that are uniformly distributed on the surface of an n-dimensional ellipsoid, (2) populating the set of regression (weight) vectors that define an elliptical arc in ℝ ⁿ , and (3) populating the set of regression vectors that have constant cosine with a target vector in ℝ ⁿ . Each algorithm is illustrated with real data. The examples demonstrate the usefulness of studying all possible criteria when evaluating alternate regression weights in regression models with a fixed set of predictors.     

Epitaxial Ni-Al thin films on NaCl using a Ag buffer layer

Epitaxial nanoscale [001] films of Ni _x Al_100-x (x = 62.5) have been prepared by physical vapour deposition on to a thin film of Ag [001] on NaCl (001) faces with occasional hillocks. The Ag film contains numerous dislocations and stacking faults and has a rms surface roughness of 2 nm. The Ni-Al film is ordered in the B2 structure and reveals many dislocations as well as antiphase boundaries between ordered domains. The formation of subgrains in the Ni-Al film results in severe height variations up to 30 nm across the surface. A cross-sectional model for the growth of both films is presented.     

Crossover from bulk to surface diffusion in the fluctuations of step edges on Pt(111)

Using low-energy electron microscopy we explore the fluctuations of step edges on Pt(111) in the temperature range 1190?K<T<1520?K. Below 1400?K the relaxation times vary with wave vector q as q ³, and above 1400?K as q ², while the observed activation energy changes from 1.25 to 2.75?eV. A discussion shows that surface diffusion is responsible for the rates at low temperatures, and that bulk vacancy diffusion becomes dominant above 1400?K. We infer that a similar crossover must occur for steps on most metal surfaces. The step stiffness is determined as 175 ± 20?meV?nm^?1 at 1500?K.     

Properties of three-dimensional bubbles of constant mean curvature

Foam bubbles of constant mean curvature with a number of faces between 3 and 32 have been computer generated. The surface area per unit volume is only weakly dependent upon the number of faces, which allows an approximate equation for the energy of a three-dimensional foam to be derived. A further relation between the rate of change in the volume of a bubble due to gas diffusion and its number of faces is compared with existing theory.     

Internet-delivered cognitive behavior therapy for anxiety and insomnia in a higher education context

Background and Objectives: Anxiety and insomnia can be treated with internet-delivered Cognitive Behavioral Therapy (iCBT). iCBT may be well-suited to students who are known to be poor help-seekers and suffer these symptoms. iCBT can offer easy access to treatment and increase service availability. The aim of this study was to evaluate the efficacy of anxiety and insomnia iCBT programs in students. Design: A randomized, controlled study. Methods: Students were randomly allocated to intervention (“Anxiety Relief”: n?=?43; “Insomnia Relief”: n?=?48; control: n?=?47). Interventions lasted six weeks. Outcome measures were the State-Trait Anxiety Inventory and the Pittsburgh Sleep Quality Index. Results: Significant within-group reductions in anxiety (t(31)?=?2.00, p?=?.03) with moderate between-groups (compared to control) effect size (d?=?.64) and increases in sleep quality (t(31)?=?3.46, p?=?.002) with a moderate between-groups effect size (d?=?.55) were found for completers of the anxiety program from pre- to post-intervention. Significant within-group increases in sleep quality were found for completers of the insomnia program from pre- to post-intervention (t(35)?=?4.28, p?>?.001) with a moderate between-groups effect size (d?=?.51). Conclusions: Findings support the use of iCBT for anxiety and insomnia in students, and indicate that further research is needed.     

Thanks to 2010 Reviewers

Abstract

The electronic conductivity, diffusion coefficient and the self-energy in the vicinity of the energy gap of amorphous Si at T=0K have been computed as a function of energy for a fully bonded model of Si. We have used the equation-of-motion method in κ-space to show, for the first time, the probable position and existence of mobility edges. The conductivity rises rapidly away from the mobility edges to take values typical of those found in liquid metals. The behaviour of the self-energy indicates that a resonance phenomenon is responsible for the formation of a gap.     

Mediation analysis of the association between use of NRT for smoking reduction and attempts to stop smoking

Objectives: Use of nicotine replacement therapy (NRT) for smoking reduction (SR) is linked to higher quit attempt rates than SR without NRT. This study aimed to assess the possible mediating roles of confidence in ability to quit, enjoyment of smoking and motivation to quit in this association.

Design: Cross-sectional survey.

Main outcome measures: Smokers were asked if they were currently attempting SR, and if they were, whether they were using NRT. Motivation to stop, enjoyment of smoking, confidence in ability to stop, and previous quit attempts, were also assessed.

Results: There was no evidence that confidence in ability to quit or enjoyment of smoking mediated the association between the use of NRT for SR and attempts to quit. Only motivation to stop partially mediated between the use of NRT for SR and attempts to stop (indirect effect: odds ratio 1.08, p?<?0.001).

Conclusion: Although this study is limited by its cross-sectional design, the findings point towards the possibility that the use of NRT to aid SR may promote attempts to stop through increasing motivation to quit but not by increasing confidence or by reducing enjoyment of smoking. Longitudinal studies are required to draw firmer conclusions about the possible mediating effects of motivation to quit.     

Reactive solid-state dewetting

High-temperature annealing in air of thick crystalline silver films deposited on high-purity nickel foils promotes solid-state dewetting, whereas no hole through the film is produced when annealing under high purity argon. Scanning electron microscopy observations of the film surface and of cross-sections reveal that dewetting occurs only if a nickel oxide layer forms at the silver-nickel interface, as a result of oxygen diffusion through the silver film. The main dewetting mechanism over short times (1h 1120K in air) is observed to be the condensation, at the silver-nickel oxide interface, of vacancies into voids which grow towards the free surface of the silver film.     

Adherence,expectations and the placebo response: Why is good adherence to an inert treatment beneficial?

Objective: The current study sought to better understand why good adherence to a placebo treatment has been reliably associated with health benefits. We proposed a model where initial expectations shape adherence, which then influences subsequent expectations that affect placebo response. Design: Seventy-two participants were told that they were enrolling in a study of physical activity and memory, and were asked to increase their physical activity by 35% for two weeks (placebo treatment). Main outcome measures: Adherence to this physical activity target was measured by pedometer. Expectations and short-term memory (free recall) were assessed before and after physical activity. Results: Initial expectations predicted adherence to physical activity (r = .27, p < .03), but adherence did not predict subsequent expectations (r = .06, p = .60). Testing a multi-step meditational model revealed that initial expectations predicted better memory even after controlling for adherence, subsequent expectations, baseline memory and gender (c’ = 1.10, 95% CI = .46–1.74). Stronger expectations for memory improvement predicted better memory performance, but adherence and later expectations did not mediate this association. Conclusions: Good adherence to a placebo may reflect strong treatment expectations which may convey benefits by enhancing the non-specific effects of treatment.     

Closing the intention–behaviour gap for sunscreen use and sun protection behaviours

Objective

Two studies were conducted with the aim of closing the intention–behaviour gap for sunscreen use and sun protection behaviours by examining the influence of self-regulatory capacity on the prediction of sunscreen use (Study 1) and self-regulatory capacity and habit on sun protection behaviours (Study 2).

Design

Studies were conducted online. Participants completed questionnaires and cognitive measures and then reported behaviour one week later.

Main Outcome Measures

Questionnaires measuring intention and cognitive tasks measuring self-regulatory capacity were administered to 209 university students. One week later, participants reported behaviour. In Study 2, questionnaires measuring intentions, and habit and cognitive tasks measuring self-regulatory capacity were administered to 178 university students who reported behaviour one week later.

Results

Intention accounted for 7.1% of variance in sunscreen use, no measures of self-regulation accounted for variance in behaviour or moderated the intention–behaviour gap (Study 1). Intention, self-regulatory capacity and habit accounted for 56.1% of variance in sun protection behaviours (Study 2). Intention, self-regulatory ability and habit predicted behaviour, while habit moderated the intention–behaviour gap.

Conclusion

Interventions aimed at increasing sun protection behaviours should take into account level of intention, self-regulatory capacity and habit. Individuals may benefit from habit formation strategies and self-regulation training.     

Effects of a prevention program for divorced families on youth cortisol reactivity 15 years later

Objective: We examined whether an empirically based, randomised controlled trial of a preventive intervention for divorced mothers and children had a long-term impact on offspring cortisol regulation.

Design: Divorced mothers and children (age 9–12) were randomly assigned to a literature control condition or the 11-week New Beginnings Program, a family-focused group preventive intervention for mothers and children in newly divorced families.

Main Outcome Measures: Fifteen years after the trial, offspring salivary cortisol (n = 161) was measured before and after a social stress task.

Results: Multilevel mixed models were used to predict cortisol from internalizing symptoms, externalizing symptoms, group assignment and potential moderators of intervention effects. Across the sample, higher externalizing symptoms were associated with lower cortisol reactivity. There was a significant group-by-age interaction such that older offspring in the control group had higher reactivity relative to the intervention group, and younger offspring in the control group exhibited a decline across the task relative to younger offspring in the intervention group.

Conclusions: Preventive interventions for youth from divorced families may have a long-term impact on cortisol reactivity to stress. Results highlight the importance of examining moderators of program effects.     

Optimism buffers the detrimental effect of negative self-perceptions of ageing on physical and mental health

Objectives: First, to replicate previous findings on the detrimental effect of negative self-perceptions of ageing (SPA) on physical health outcomes and to expand them to the prediction of mental health; second, to test whether an optimistic outlook to the future can buffer the effect of negative SPA on physical and mental health outcomes.

Design: Data for this study comes from the 2008 and 2011 waves of the German Ageing Survey (DEAS; n?=?6205), a population-based representative survey of adults aged 40–85?years. Mean age of the participants was 61.50 (±12.1), 49.5% were women.

Main Outcome Measures: Self-rated health, physical functioning and depressive symptoms.

Results: Multiple regression analyses indicated that negative SPA predicted deterioration in the three health outcomes over a three-year period, controlling for demographics and illnesses. The most remarkable finding is the interaction with optimism: People who were prepared for physical losses (negative SPA), and who were nevertheless optimistic, were better able to maintain better physical functioning, and lower depressive symptoms.

Conclusion: A multidimensional perspective on ageing, considering both gains and losses at the same time, seems to be best for the maintenance of good health. Individual and societal positive views of ageing should be encouraged.     

Randomized controlled trial evaluating the effectiveness of a web-based stress management program among community college students

Background and Objectives: This study evaluated the effectiveness of a web-based stress management program among community college students that focused on increasing perceived control over stressful events. Design: Students (N = 257) were randomly assigned to a Present Control Intervention or a Stress-information only comparison group. Methods: Primary outcomes were perceived stress and stress symptoms; secondary outcomes were depression and anxiety. Self-report measures were completed online at preintervention, postintervention, and three-week follow-up. Intervention effects were estimated using linear mixed models. Seventy-five percent of the sample (n = 194) completed the pretest and comprised the intent-to-treat sample. Results: Participants in the intervention group reported significant increases in present control, and significant decreases in all four primary and secondary outcome measures from baseline to postintervention and follow-up. Within-group effect sizes were small to medium at postintervention (mean d = –.34) and follow-up (mean d = –.49). The mean between-group effect size on the four outcome measures was d = .35 at postintervention but d = .12 at follow-up, due to unexpected decreases in distress in the comparison group. Conclusions: Our online program is a cost-effective mental health program for college students. Limitations and future direction are discussed.     

Development and Evaluation of a Decision Aid About Prenatal Testing for Women of Advanced Maternal Age

Objective: To develop and evaluate a decision aid designed to prepare patients of advanced maternal age for counseling about prenatal diagnostic testing. Setting: A regional genetics center. Design: A before/after study. Interventions: Participants used an audioguided workbook to learn about options and outcomes and to clarify personal risks, values, questions, and predispositions. Subjects: 21 women of advanced maternal age and 17 spouses. Main outcome measures: Knowledge of prenatal testing alternatives, decisional conflict, level of anxiety, and acceptability of the decision aid. Results: After using the decision aid, participants had significantly reduced decisional conflict (uncertainty) and a significant increase in knowledge. There was no effect on state or trait anxiety. More than three-quarters of participants were satisfied with the length, clarity, balance, and acceptability of the decision aid. Conclusions: The decision aid shows promise as a useful aid for preparing couples for counseling.     

The relative importance of patients’ decisional control preferences and experiences

Objective: Patients’ role in treatment decision-making can influence psychosocial and health-related outcomes (i.e. satisfaction, felt respect, adherence). We examined decisional control in a surgical context, identifying correlates of patients’ preferences and experiences.

Design: 380 patients and 7 surgeons were surveyed during initial surgical consultation visits in a low-income outpatient clinic.

Measures: Patients reported preferences for (pre-consultation) and experiences of (post-consultation) decisional control, demographics, satisfaction with care, and adherence to treatment recommendations. Surgeons rated patients’ health status.

Results: Preferences for and experiences of decisional control were unrelated, suggesting significant preference–experience misalignment. However, this misalignment did not appear to be consequential for patient outcomes. Rather, more decisional control, regardless of patients’ preferences, predicted greater satisfaction with care and greater self-reported adherence as assessed at a post-surgical appointment.

Conclusions: Decisional control predicts better outcomes for patients, regardless of their preferences for control over treatment decisions. These findings suggest that interventions should aim to increase patients’ degree of decisional control when feasible and appropriate.     

Predicting intention and behaviour following participation in a theory-based intervention to improve gluten free diet adherence in coeliac disease

Objective: To determine whether changes in theory of planned behaviour (TPB) constructs could predict intention and gluten-free diet (GFD) adherence following participation in an online theory-based intervention designed to improve adherence in coeliac disease.

Design: Theory-based process evaluation of the mechanisms of change over the course of a six-week online intervention. Measures of GFD adherence and TPB variables were administered at baseline and follow-up (immediate post-intervention: n = 74; three-month: n = 68; six-month: n = 65). Hierarchical regression analyses using residualised change scores were conducted at each time point (dependent variables: intention and adherence).

Results: Baseline intention and GFD adherence were the strongest predictors of follow-up intention and adherence, respectively. Change in attitude accounted for significant variance in intention. Change in intention accounted for significant variance in GFD adherence immediately post-intervention; by the six-month follow-up change in perceived behavioural control was the stronger predictor.

Conclusions: Partial support for the hypotheses suggests that, for certain behaviours, the TPB may be relevant in explaining the mechanism of action responsible for changes in intention and behaviour following participation in a behaviour change intervention. Additional predictive pathways are also likely to exist and, in the area of GFD adherence, may include habit strength and actual behavioural control.