Kinetics of persistent photoconductivity in crystalline III–V semiconductors

Although persistent photocurrent (PPC) in photoconductive III–V semiconductors is known to be dominated by dispersive reaction kinetics, which produce a stretched exponential function decay, exp[?(t/τ)^β], where τ is the effective reaction time and β (<1.0) is the dispersion parameter, the reason for the occurrence of the PPC is still not clear. Here, we discuss the origin of dispersive kinetic relaxation associated with a DX-like centre, i.e. deep levels associated with donors in III–V semiconductors. It is suggested that lattice relaxation of DX-like centres, accompanied by multi-phonon processes, may play a role in the dispersive nature of the PPC.     

Transient photoconductivity in n-type a-Si: H

Abstract

The long-time transient photocurrent decay in annealed and light-exposed P-doped a-Si: H is examined experimentally and by numerical modelling. The decay is a dispersive power law with sublinear index, extending to times longer than 1s, and the decay rate increases with temperature. Light exposure dramatically decreases the decay amplitude but does not affect the rate of decay. The phenomenon is discussed in terms of a comprehensive multiple-trapping model in which transport of thermalized electrons is essentially non-dispersive, and recombination of free carriers via defects is dispersive, owing to continued thermalization of excess holes. The slower recombination step is free-hole capture by D^? states, while the decay of the total excess ensemble is controlled by hole release from valence-band tail traps. The index of the excess photoelectron decay provides information on the valence-band tail states, which are exponentially distributed, with a characteristic energy estimated as 0·06 eV.     

In situ simultaneous measurements of photodarkening and photoinduced defect creation in amorphous As2Se3 films

To understand the direct correlation between photodarkening (PD) and photoinduced defect creation (PDC) observed in amorphous chalcogenides, in situ simultaneous measurements of PD and photocurrent (PC) have been performed on amorphous As₂Se₃ films. The time evolution of PD and PDC during light excitations are empirically described by a stretched exponential function; 1 ??exp[?(t/τ) ^β ], where τ is the effective response time and β the dispersion parameter. The value of τ for the PDC is very much smaller than that for the PD, suggesting that there is no direct correlation between the two.     

The role of the Five Factor Model of personality in the perceptions of negative and positive forms of work–nonwork spillover: A meta-analytic review

The present meta-analysis examines the relationships between the Five Factor Model (FFM) of personality and negative and positive forms of work–nonwork spillover (e.g., work-family conflict and facilitation). Results, based on aggregated correlations drawn from 66 studies and 72 independent samples (Total N = 28,127), reveal that the FFM is predictive of work–nonwork spillover. More specifically, meta-analytic structural equation modeling indicated that extraversion (β = −.08), agreeableness (β = −.06), conscientiousness (β = −.13), and neuroticism (β = .29) are related to negative work–nonwork spillover, while extraversion (β = .27), agreeableness (β = .11), conscientiousness (β = .12), and openness to experience (β = .20) are related to positive work–nonwork spillover. FFM personality variables were equally predictive of both directions of spillover (i.e., work-to-nonwork and nonwork-to-work). Collectively these results suggest a moderate amount of variance in negative (R² = .15) and positive (R² = .18) work–nonwork spillover is accounted for by personality.     

Ghrelin level negatively predicts quality of life in obese women

A cross-sectional cohort study was conducted to investigate whether ghrelin level in obese women predicts the quality of life (QOL). A total of 307 subjects fulfilled the criteria: (1) age between 20 and 65 years old, (2) body mass index ≥27 kg/m² (3) waist circumference ≥80 cm were enrolled in the study. All subjects were assigned to one of the plasma ghrelin level categories according to the quartiles. The median of age and BMI of the 307 obese women were 45 ± 18 years and 29.9 ± 4.1 kg/m², respectively. The main outcome evaluated is the associations of plasma ghrelin level and QOL, which were evaluated using multiple linear regression analysis. Results of linear trend test show significant statistical difference in plasma lipoproteins (triglyceride, cholesterol, HDL-cholestero and LDL-cholesterol = and levels of obesity-related hormone peptides, including leptin, adiponectin, insulin among quartiles of ghrelin. Multiple liner regression analysis of serum obesity-related hormone peptide level and QOL using stepwise method shows ghrelin concentration was the only predictor of QOL, including PCS-12 level (β = ?0.18, p = 0.001), MCS-12 level (β = ?0.14, p = 0.009), WHOQOL-BREF scores: physical (β = ?0.13, p = 0.03), psychological (β = ?0.16, p = 0.007), social (β = ?0.21, p?= < 0.001), and environmental (β = ?0.22, p?= <0.001), after adjusting other factors for obese female subjects. This study demonstrated that ghrelin concentration is strongly associated with QOL level among obese women. Hence, ghrelin concentration might be a valuable marker to be monitored in obese women.     

Insomnia symptoms are associated with elevated C-reactive protein in young adults

Abstract

Objective: Insomnia is associated with elevated inflammation; however, studies have not investigated if this relationship is confounded with depression and neuroticism, which are associated with insomnia and inflammation. The current study examined the association of insomnia symptoms with C-reactive protein (CRP) and with interleukin-6 (IL-6), independently and after controlling for depressive symptoms and neuroticism. Design: Fifty-two young adults (mean age?=?25.2?±?3.9 years, 52% female) completed a baseline survey to assess psychological characteristics, followed by a plasma blood draw. Main outcome measures: Plasma CRP and IL-6. Results: When examined alone, insomnia symptoms were significantly associated with elevated CRP (β?=?0.52; R²?=?0.27), as was neuroticism (β?=?0.41, R²?=?0.17), but not depressive symptoms (β?=?0.21, R²?=?0.05). The association between insomnia symptoms and CRP remained significant when depressive symptoms and neuroticism were entered into the model simultaneously; this model did not explain more variance than the model with insomnia symptoms alone. No variables were associated with IL-6. Conclusions: Results suggest that insomnia symptoms are independently associated with elevated CRP in young adults, even after controlling for presumed overlapping psychological constructs. Findings highlight the potential importance of treating insomnia to reduce systemic inflammation.     

Relations between symptom severity,illness perceptions,visceral sensitivity,coping strategies and well-being in irritable bowel syndrome guided by the common sense model of illness

Irritable Bowel Syndrome (IBS) is a common condition affecting around 10–20% of the population and associated with poorer psychological well-being and quality of life. The aim of the current study was to explore the efficacy of the Common Sense Model (CSM) using Structural Equation Modelling (SEM) in an IBS cohort. One hundred and thirty-one IBS patients (29 males, 102 females, mean age 38 years) participating in the IBSclinic.org.au pre-intervention assessment were included. Measures included IBS severity (Irritable Bowel Syndrome Severity Scoring System), coping patterns (Carver Brief COPE), visceral sensitivity (Visceral Sensitivity Index), illness perceptions (Brief Illness Perceptions Questionnaire), psychological distress (Depression, Anxiety and Stress Scale), and quality of life (IBS Quality of Life scale; IBS-QoL). Using SEM, a final model with an excellent fit was identified (χ² (8) = 11.91, p = .16, χ²/N = 1.49, CFI > .98, TLI > .96, SRMR < .05). Consistent with the CSM, Illness perceptions were significantly and directly influenced by IBS severity (β = .90, p < .001). Illness perceptions in turn directly influenced maladaptive coping (β = .40, p < .001) and visceral sensitivity (β = .70, p < .001). Maladaptive coping and visceral sensitivity were significantly associated with psychological distress (β = .55, p < .001; β = .22, p < .01) and IBS-QoL (β = –.28, p < .001; β = –.62, p < .001). Based on these findings, we argue that to augment the adverse impact of IBS severity on IBS-QoL and psychological distress, psychological interventions will be best to target the mediating psychological processes including illness beliefs, visceral sensitivity and maladaptive coping.     

When does anxiety help or hinder cognitive test performance? The role of working memory capacity

Cognitive interference theories (e.g. attentional control theory, processing efficiency theory) suggest that high levels of trait anxiety predict adverse effects on the performance of cognitive tasks, particularly those that make high demands on cognitive resources. We tested an interaction hypothesis to determine whether a combination of high anxiety and low working memory capacity (WMC) would predict variance in demanding cognitive test scores. Ninety six adolescents (12‐ to 14‐years‐old) participated in the study, which measured self‐report levels of trait anxiety, working memory, and cognitive test performance. As hypothesized, we found that the anxiety‐WMC interaction explained a significant amount of variance in cognitive test performance (ΔR² .07, p < .01). Trait anxiety was unrelated to cognitive test performance for those adolescents with average WMC scores (β = .13, p > .10). In contrast, trait anxiety was negatively related to test performance in adolescents with low WMC (β = ?.35, p < .05) and positively related to test performance in those with high WMC (β = .49, p < .01). The results of this study suggest that WMC moderates the relationship between anxiety and cognitive test performance and may be a determinant factor in explaining some discrepancies found in the literature. Further research is needed to fully understand the mechanisms involved.     

Two alternative models of health behaviour and recovery from activity limitations due to acute injury: A prospective study

Cognitions influence recovery from activity limitations. In this study we aimed to independently test, compare and combine the common sense self-regulation model (CS-SRM) and social cognitive theory (SCT) in predicting recovery from activity limitations due to acute injury. Measures were gathered at two time points 5–6 weeks apart. The sample consisted of 146 university students (Mean age: 21.86, SD: 4.83, 62% female) with a heterogeneous range of injuries that limited their participation in physical activity. The dependent variable was recovery from activity limitations (Physical Functioning?–?Short Form-36). The predictor variables were measured using the Brief Illness Perception Questionnaire and SCT items designed according to theoretical recommendations. Time-line (TL) and self-efficacy (SE) were significant predictors of recovery in a multivariate analysis, controlling for reported pain at Time 1. A combined model including the best predictors from both models, TL (β = ?0.25, p < 0.05, R ² change = 0.17, p < 0.01) and SE (β =0.31, p < 0.05, R ² change = 0.05, p < 0.05), accounted for a significant amount of the variance in recovery from activity limitations. A combination of key variables from both models may be particularly useful for understanding the cognitive factors that influence recovery from activity limitations.     

Self-efficacy,psychological adjustment and decisional-balance regarding decision making for outpatient chemotherapy in Japanese advanced lung cancer

This study examined the application of the trans-theoretical model (TTM) for readiness for decision-making of outpatient chemotherapy of Japanese advanced lung cancer patients by a cross sectional questionnaire survey. A questionnaire was conducted with 105 Japanese patients diagnosed with advanced lung cancer receiving chemotherapy. We classified them according to the TTM stages, including 4 in precontemplation, 42 in contemplation, 22 in preparation, and 35 in action. The valid model (χ ² (37) = 42.56, p = 0.24; GFI = 0.93; AGFI = 0.88; CFI = 0.98; RMSEA = 0.04; AIC = 100.56) derived from structural equation modeling (SEM) revealed that stage of outpatient chemotherapy was significantly affected mostly by decisional-balance (β = 0.60, p < 0.001) and partially by time from the patient's house to the hospital (β = ?0.15, p < 0.10), and that decisional-balance was significantly affected by self-efficacy (β = 0.48, p < 0.001) and nausea (β = ?0.23, p < 0.01). The findings from our study provided encouraging results for adopting the TTM in decision making for outpatient chemotherapy in Japanese cancer care and several clinical implications were obtained from the results.     

Students' defending and passive bystanding behaviours when witnessing school bullying in North Western Ethiopia: Roles of personal and situational factors

Guided by Thornberg et al.'s (2012) framework on motivation to intervene, the present study examines whether personal and situational factors are associated with defending and passive bystanding behaviours in school bullying. Self-reported survey data were collected from 612 students (aged 12–16 years) attending grades 7, 8, 9, and 10 in East Gojjam Administrative Zone, North Western Ethiopia. Hierarchical regression analysis revealed that the strongest, significant predictors of defending were self-efficacy for defending (β = .215, p = .000), affective empathy (β = .173, p = .000), students' experience as victim (β = .119, p = .002), personal sense of power (β = .119, p = .006), followed by moral disengagement (β = .118, p = .002), and age level (β = −.082, p = .036). All variables jointly explained 18.6% of the total variance in defending, F (12, 599) = 11.397, p < .00; with medium effect size (f² = 0.23). In contrast, the strongest predictors of passive bystanding were moral disengagement (β = .233, p = .000), perceived costs and benefits of defending (β = −.163, p = .000), self-efficacy (β = −.139, p = .003), students' experience as victim (β = .097, p = .014), followed by gender (β = −.080, p = .042). The model explained 16.7% of the total variance in passive bystanding, F (12, 599) = 10.043, p < .001; with medium effect size (f² = 0.20). The findings enrich our understanding of factors associated with defending and passive bystanding behaviours. The implications for intervention are discussed. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement.     

Horizontal and vertical attentional orienting in Parkinson’s disease

Patients with Parkinson’s disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N = 10), RPD (N = 9) and controls (N = 10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinson’s disease – particularly in LPD – from very subtle slowing to clinically detectable horizontal and/or vertical neglect.     

Horizontal and vertical attentional orienting in Parkinson’s disease

Patients with Parkinson’s disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N = 10), RPD (N = 9) and controls (N = 10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinson’s disease – particularly in LPD – from very subtle slowing to clinically detectable horizontal and/or vertical neglect.     

Collaborative communication efficiency is linked to relationship satisfaction in dating couples

The speed, or efficiency, in which people communicate is linked to positive interpersonal outcomes. However, no studies of communication efficiency have examined romantic partners, making it unclear whether efficient communication is linked to relationship satisfaction above and beyond previously identified communication skills (e.g., problem‐solving). We recruited dating couples (N = 56) to attend a laboratory session to complete survey measures and a collaborative communication task. Multilevel models demonstrated that both task efficiency (β = ?.36, p = .04) and self‐reported problem‐solving communication skills (β = .28, p = .002) were associated with relationship satisfaction. Results suggest that communication task efficiency can be meaningfully applied to the study of romantic relationships and couple communication skills.     

Serum β-Amyloid Correlates with Neuropsychological Impairment

ABSTRACT

Aims: Evidence suggests a relationship between peripheral Aβ and AD. We hypothesized that higher levels of serum Aβ_1–42 would be associated with memory impairment, thought to occur early in the disease, and rises in serum Aβ_1–40, which occur later, would be associated with impairment in non-memory measures. Methods: Using a cross-sectional design, we examined the relationship of serum Aβ_1–40, Aβ_1–42, and the ratio of Aβ_{1–42/1–40} to neuropsychological measures in 40 cognitively normal controls, 13 MCI subjects, and 25 AD patients. Results: Serum Aβ_1–42 and the ratio of Aβ_{1–42/1–40} were significantly higher in the MCI group compared to the controls. A significant relationship in the hypothesized direction (poorer scores associated with higher Aβ_1–40 serum levels) was found between Aβ_1–40 and measures of executive functions across the entire cohort of individuals tested and with measures of language and processing speed in the AD group. Regression analysis found that neuropsychological measures accounted for 26% of the variance in serum Aβ_1–40, in the MCI/AD but not the controls. Furthermore that language and executive measures were significant predictors. Conclusions: Results provide preliminary data to partially support our hypotheses and suggest that changes in serum Aβ levels may be attributed to pathological changes within the brain.     

Determination of Peierls stress from acoustic harmonic generation

The interaction of acoustic waves with dislocations leads to aperiodic oscillations in the magnitude of the acoustic nonlinearity parameter β as a function of the acoustic drive amplitude σ _ampl. The magnitude and spacing of the oscillations depend on the value of the Peierls stress. A least-square curve fit of the β(σ _ampl) equation to experimental data taken of 99.999% pure aluminum monocrystals oriented for wave propagation along the [1?0?0] crystal axis yields the value 6.2?×?10⁴?Pa for the Peierls stress. The value is consistent with the smallest values reported in the literature for aluminum where for both theoretical and experimental studies the reported values range over three orders of magnitude.     

The shared and unique genetic relationship between mental well-being,depression and anxiety symptoms and cognitive function in healthy twins

Alterations to cognitive function are often reported with depression and anxiety symptoms, yet few studies have examined the same associations with mental well-being. This study examined the association between mental well-being, depression and anxiety symptoms and cognitive function in 1502 healthy adult monozygotic (MZ) and dizygotic (DZ) twins, and the shared/unique contribution of genetic (G) and environmental (E) variance. Using linear mixed models, mental well-being was positively associated (p?β?=?0.127), inhibition (β?=?0.096), cognitive flexibility (β?=?0.149), motor coordination (β?=?0.114) and working memory (β?=?0.156), whereas depression and anxiety symptoms were associated (p?β?=??0.134), inhibition (β?=??0.139), cognitive flexibility (β?=??0.116) and executive function (β?=??0.139). Bivariate twin modelling showed well-being shared a small environmental correlation with motor coordination and a small genetic correlation with working memory. Trivariate twin modelling showed well-being shared a small genetic correlation with inhibition, whereas depression and anxiety symptoms shared a small environmental correlation with inhibition. The remaining variance was mostly driven by unique G and/or E variance. Overall, well-being and depression and anxiety symptoms show both independent and shared relationships with cognitive functions but this is largely attributable to unique G or E variance and small shared G/E variance between pairs of variables.     

Neurocognitive Function and Suicide in U.S. Army Soldiers

This prospective cohort study used administrative data from the Army Study to Assess Risk and Resilience in Servicemembers to examine associations between neurocognitive functioning and subsequent suicidal events among Regular Army enlisted soldiers during the years 2004–2009. Cases were all soldiers who completed the Army's Automated Neuropsychological Assessment Metrics (ANAM) computerized testing battery prior to documented suicide attempt (n = 607), ideation (n = 955), or death (n = 57). Controls were an equal‐probability sample of 9,893 person‐months from other soldiers. Exploratory factor analysis of five ANAM tests identified a general neurocognitive factor that excluded the mathematic processing test (MTH). When examined separately in logistic regression analyses that controlled for sociodemographics and prior mental health diagnosis, both the general neurocognitive factor (logit [β] = ?.197 to ?.521; p < .01) and MTH (β = ?.024 to ?.064; p < .05) were associated with all outcomes. When both predictors were examined simultaneously, the general neurocognitive factor continued to be associated with all outcomes (β = ?.164 to ?.417; p < .05) and MTH continued to be associated with suicide attempt (β = ?.015; p = .046) and ideation (β = ?.014; p = .018). These small but robust associations suggest that future research must continue to examine the extent to which objective neurocognitive tests may enhance understanding and prediction of suicide risk.     

A generalization of Piéron's law to include background intensity and latency distribution

Piéron's law, which formulates the effect of the signal intensity i on the mean or the median reaction time (MRT) as a power function, MRT=R+i^-βC, in which R, β and C are positive parameters, is of much interest in the simple reaction time literature. In particular, consistent estimates of β are obtained. However, this law offers no information regarding the effect of the signal intensity on other aspects of the reaction time distribution. In addition, the background intensity, which also has some impact on the detectability of the signal, is not considered in Piéron's law. In this paper, we generalize Piéron's law based on the above comments. That is, we assume that both β and C are functions of the background intensity and of the percentile rank. We then investigate from a theoretical viewpoint some possible functional forms of β and C, with a special emphasis on the dependency of β on the background intensity. It is shown that the so-called “Fechner-Thurstone-type representation” forces β and C to be “separable.” If we further assume a near-miss to Weber's law-type representation, then the functional form of β can be determined.