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.     

Interpretation of the low-temperature photoconductivity in a-Si

Abstract

The paper is concerned with the interpretation of steady-state photoconductivity results on undoped a-Si at temperatures of 50K and below which lead to an essentially constant value of the (photogeneration efficiency x mobility x lifetime) product νμτ?10^?11 cm² V^?1. Measurements on p⁺-i-n⁺ junctions and Cr-i-n⁺ barriers were carried out to determine the above parameters separately: (i) steadystate reverse saturation currents gave a generation efficiency of ν? 5×10-² below 50K, suggesting that geminate recombination limits the generation process. (ii) the electron drift mobility μ_e through the tail states and the charge extracted from the absorption region of the incident light were investigated by transient experiments, these showed that μ_eτ_a is limited to about 3×10^?10cm²V^?1 at low T. The independent results account for the observed νμτ values and suggest that, contrary to the interpretation of Hoheisel, Carius and Fuhs (1984), the main contribution to the low-temperature photoconductivity arises from transport in tail states.     

The effect of hydrogen plasma on the properties of a-Si:H/a-Si1-xNx:H superlattices

Abstract

A hydrogen plasma introduced during the interrupting interval when alternating two gases affects the properties of a-Si:H/a-Si_1-xN_x:H superlattices resulting in the creation of fewer interface defects than the superlattices prepared without the hydrogen plasma.     

Dependence on Wrongdoing in the Consumption of Meat: A Kantian Analysis

Kant's ethics is used by some as a defence of the exploitation of animals and is criticised by others for not recognising any moral relevance of the plight of animals. These appeals overlook the broad applicability of Kant's principles. In this article, I argue that Kant's ethics implies a duty to abstain from most meat and some other animal products derived from farming. I argue that there is a Kantian principle not to choose goods that have been derived from wrongdoing, with certain qualifications. This principle isolates the wrong of using others to commit wrongdoing on one's behalf. As has been argued by others, Kant's ethics implies that animal farming as we know it in our society almost universally involves wrongdoing and the slaughter of animals is especially tied to wrongdoing. I argue for a broad sense in which these ideas together imply that choosing farmed meat, and probably other animal products, is treating animal industry workers as mere means. Thus, we have a Kantian duty to abstain from these products.     

药物依赖患者脑功能成像研究结果综述

介绍了脑功能成像技术对药物依赖的中枢机制、药物相关线索对患者的作用以及药物对大脑的长期作用的主要研究结果,这些结果对进一步了解药物依赖行为具有重要意义     

Dependence and physical exercise: Spanish validation of the Exercise Dependence Scale-Revised (EDS-R)

The purpose of this study was to validate the Spanish version of the Exercise Dependence Scale-Revised (EDS-R). To achieve this goal, a sample of 531 sport center users was used and the psychometric properties of the EDS-R were examined through different analyses. The results supported both the first-order seven-factor model and the higher-order model (seven first-order factors and one second-order factor). The structure of both models was invariant across age. Correlations among the subscales indicated a related factor model, supporting construct validity of the scale. Alpha values over .70 (except for Reduction in Other Activities) and suitable levels of temporal stability were obtained. Users practicing more than three days per week had higher scores in all subscales than the group practicing with a frequency of three days or fewer. The findings of this study provided reliability and validity for the EDS-R in a Spanish context.     

Deflationism and the Dependence of Truth on Reality

A common objection against deflationism is that it cannot account for the fact that truth depends on reality. Consider the question ‘On what does the truth of the proposition that snow is white depend?’ An obvious answer is that it depends on whether snow is white. Now, consider what answer, if any, a deflationist can offer. The problem is as follows. A typical deflationary analysis of truth consists of biconditionals of the form ‘The proposition that p is true iff p’. Such biconditionals tell us nothing about what the truth of the proposition that p might depend on. Therefore, it seems that a typical deflationist cannot give an answer. Since we know that an answer is available, this throws doubt over the adequacy of deflationism as an account of truth. Articulated here is a defence of deflationism against this objection. It is argued that although biconditionals of the sort mentioned do not explicitly state a dependency between truth and reality, they nevertheless convey one. The reason is that, given the context in which a deflationist invokes the biconditionals, such a dependency is implicated. A potential problem with this defence is that it leaves the deflationist still unable to give an account of what it is for truth to depend on reality. One might think that a deflationist can offer such an account by appealing to truthmaker theory but, it is argued below, truthmaker theory is unavailable to a deflationist. Instead, the deflationist should question the assumption that an account is available.     

Origin of the hardness enhancement in superhard nc-TiN/a-Si3N4 and ultrahard nc-TiN/a-Si3N4/TiSi2 nanocomposites

The ideal shear strengths of a variety of TiN/SiN _x /TiN interfaces have been calculated with the ab initio density functional theory. Using these data, the high hardness H?≥?105?GPa, which has been reported for the quasi-ternary nc-TiN/a-Si₃N₄/TiSi₂ nanocomposites, can be explained on the basis of the Sachs average of polycrystal plasticity of randomly oriented equiaxed grains and pressure-enhanced flow stress.     

Neurocognitive impairments in boys on the life-course persistent antisocial path

This study addresses 5 unresolved issues in the neuropsychology of antisocial behavior using a community sample of 325 school boys in whom neurocognitive measures were assessed at age 16-17 years. Antisocial behavior measures collected from age 7-17 years were cluster analyzed and produced 4 groups: control, childhood-limited, adolescent-limited, and life-course persistent. Those on the lifecourse persistent path and also on the childhood-limited path were particularly impaired on spatial and memory functions. Impairments were independent of abuse, psychosocial adversity, head injury, and hyperactivity. Findings provide some support for the life-course persistent versus adolescent-limited theory of antisocial behavior and suggest that (a) neurocognitive impairments are profound and not artifactual and (b) childhood-limited antisocials may not be free of long-lasting functional impairment.     

依赖结构对信任行为的影响:基于互依理论的视角

信任是人际互动中的重要主题,受到诸多因素的影响,越来越多的研究者关注情境特征对信任的影响。以相互依赖理论为基础,操作依赖的相互性、依赖水平和利益协同,构建互动双方间不同的依赖结构,分析不同依赖结构对被试信任的影响。结果表明:(1)在双向依赖情境中被试的信任水平显著高于单向依赖情境;(2)单向依赖、低利益协同情境中,依赖水平对个体的信任行为有显著影响,双向依赖、高利益协同情境中,依赖水平对个体信任行为的影响不显著;(3)单向依赖、低依赖水平情境中,利益协同对信任行为有显著影响,双向依赖、高利益协同情境中,利益协同对信任行为影响不显著。     

Developmental Trajectories of Religious Service Attendance: Predictors of Nicotine Dependence and Alcohol Dependence/Abuse in Early Midlife

Journal of Religion and Health - This longitudinal study assesses the associations between developmental trajectories of religious service attendance from mean age 14 to mean age 43 and nicotine...