Positron lifetime study of an Al-1.7at.% Mg-1.1at.% Cu alloy

The behaviour of vacancies during isothermal ageing following quenching of an Al-1.7at.% Mg-1.1at.% Cu alloy has been studied by positron annihilation lifetime spectroscopy. The positron lifetime parameters vary in parallel with the Vickers hardness of the alloy, suggesting simultaneous migration of vacancies and changes in the size and concentration of vacancies containing clusters and dislocation loops. The results also explain the long hardness plateau observed previously in ageing experiments carried out between 100 and 240°C in terms of a continuous growth of Mg-Cu-vacancy clusters during ageing. The vacancy concentration of the clusters increases gradually until the setting in of the cluster Guinier-Preston-Bagaryatsky zone transformation.     

Grain boundary phase observed in Al–5 at.% Zn alloy by using HREM

The nature and behaviour of grain boundary (GB) phases is very important since they can control strength, plasticity, resistivity, grain growth, corrosion resistance, etc, especially in nanocrystalline materials. For nanocrystalline Al-based light alloys, extremely high plasticity has been observed in restricted temperature and concentration intervals close to the solidus line. This phenomenon is not fully understood. It can be explained by formation of GB phases not included in the bulk phase diagram. Therefore, the structure of GB phases, as well as thermodynamic conditions for their existence, has to be carefully studied. In this work the structure and composition of GBs and GB triple junctions in Al–5 at.% Zn polycrystals annealed in the temperature region above and below the bulk solidus line were studied by high-resolution electron microscopy and analytical transmission electron microscopy. Evidence has been obtained that a thin layer of a liquid-like phase exists in GBs and GB triple junctions slightly below the bulk solidus line.     

Accumulation of geometrically necessary dislocations near grain boundaries in deformed copper

Cross-correlation-based analysis of electron backscatter diffraction patterns has been used to map the distribution of geometrically necessary dislocation (GND) density in deformed polycrystalline copper. Patterning of the dislocations into high-density cell walls and low-density cell interiors was readily observed at the micron scale. Patterning at the longer length scale of the grain size was also evident with high-density regions (GND hot spots) tending to be in clusters, often found close to some but not all grain boundaries and triple junctions.     

Fragmentation testing for ductile thin films on polymer substrates

Fragmentation testing of thin films on substrates has in the past been mostly performed in situ using optical and scanning electron microscopy. While these techniques work well for brittle materials, they cannot always discern the difference between through-thickness cracks (TTCs) and localized plastic deformation of ductile films. Here, we describe fragmentation testing with atomic force microscopy and present criterion to distinguish TTCs and localized deformation for ductile films.     

阻塞性睡眠呼吸暂停低通气综合征对心血管系统的影响

阻塞性睡眠呼吸暂停低通气综合征(OSAHS)是常见却又不被广泛认识的疾病,可以导致多种器官和系统的损害,特别是心血管系统的损害.随着肥胖人群的增加,OSAHS的患病率有可能继续升高,这已经是一个重要的公共卫生问题,本文就OSAHS导致心血管疾病的发病机制,对常见心血管疾病的影响进行探讨.     

Guest Editorial: The Resistance to Belief

William James's essay The Will to Believe proposed that we are sometimes justified, even obligated, to believe from our strong emotional or passional nature that something is true, even though there may not be total logical, evidential proof—which he also wrote is not to be found in this world. This essay explores situations, using a recent dear-death experience (NDE) example, in which there are reasonable evidence and logic, and yet belief seems to be withheld. I postulate and discuss nonrational influences producing resistance to belief, including the fear of being in error, the fear of rejection from the scientific community, irrational requirements of logicality, avoidance of consequences, and paradigm fixation. I also discuss issues in philosophy of science and epistemology in regard to proof.     

The potential mediating role of anxiety sensitivity in the impact of mindfulness training on anxiety and depression severity and impairment: A randomized controlled trial

The benefits of mindfulness-based interventions to alleviate anxiety and depression have been supported by many studies. Given the effectiveness of mindfulness-based interventions on anxiety and depression, the underlying mechanisms need to be explored. Using a randomized waitlist-controlled design, this study investigated whether anxiety sensitivity was a potential mechanism for the impact of mindfulness training on anxiety and depression. Participants with high psychological distress were randomly assigned to an eight-week mindfulness intervention (N = 35) or a wait-list control group (N = 34). Before and after the intervention or corresponding waitlist period, participants completed measures of anxiety and depression severity and impairment and anxiety sensitivity. Separate mixed ANOVA demonstrated significant group (intervention vs. control group) × time (pre- vs. post-test) interactions for anxiety sensitivity and overall anxiety severity and impairment and marginally significant interaction for overall depression severity and impairment. Moreover, simple mediation models showed that reductions of anxiety sensitivity from pre- to post-test mediated the impact of mindfulness training on changes in anxiety and depression severity and impairment. The findings suggest that anxiety sensitivity is a potential mechanism underlying the effect of mindfulness training on anxiety and depression, which provides a new perspective for the study of processes of change of mindfulness-based interventions.     

Change mechanisms in cognitive therapy of a simple phobia: Logical analysis and empirical hypothesis testing

The effectiveness of two hypothesized change mechanisms in cognitive therapy was investigated: logical analysis and empirical hypothesis testing. Thirty-eight spider phobics, as determined by performance on a behavioral avoidance test, were randomly assigned to either one of these two conditions or to a no-treatment control condition. Subjects participated in three group sessions. Outcome phobia questionnaire data suggested that both mechanisms produced desirable changes in a short period of time, with stronger evidence that logical analysis was superior to the control. Outcome from the behavior avoidance test and self-efficacy ratings failed to reach statistical significance but the trends were in the direction of positive change. Results are discussed in terms of the tripartite response dessynchrony hypothesis. Suggestions for future process research in cognitive therapy are provided.William O'Donohue, Ph.D., is an assistant professor of psychology at Northern Illinois University.Jeff Szymanski is a graduate student in clinical psychology at Northern Illinois University.The authors would like to thank Christine Casselles, Melissa McKelvie, Thomas M. Brown, Jill C. Rudman, Bonnie Schrieber, Amy Ray, Anne Valle, Lisa Herold, Jacqueline Ryan, Heather Barta, and Angela Leek for their assistance in this project. Moreover, the authors are grateful to Sol Feldman and Jane Fisher for their comments on an earlier version of this paper.     

A cellular analogue of operant conditioning.

Using the hippocampal-slice preparation, we attempted to model operant conditioning in vitro by reinforcing pyramidal cell bursting responses with local micropressure applications of transmitters and drugs. The same injections were administered independently of bursting to provide a "noncontingent" control for direct pharmacological stimulation or facilitation of firing. The results suggested that the bursting responses of individual CA1 pyramidal neurons may be reinforced in a dose-related manner by response-contingent (but not noncontingent) injections of dopamine and the selective dopamine D2 agonist, N-0923. N-0924, a stereoisomer of N-0923 that is largely devoid of D2-agonist activity, failed to reinforce CA1 bursting. Burst-contingent injections of the excitatory neurotransmitter glutamate also failed to reinforce CA1 bursting; indeed, the glutamate applications (whether contingent or random) reduced the likelihood of bursts while increasing the frequency of solitary spikes. Reinforcement delays exceeding 200 ms largely eliminated the reinforcing efficacy of the D2 agonist N-0437 in CA1 operant conditioning. The results are consistent with the suggestion that the behaviorally reinforcing effects of dopaminergic agents can be modeled in vitro in the hippocampal-slice preparation.     

A brief history of Russian aphasiology

This paper analyzes early Russian contributions to the study of aphasia, dated between 1789 and 1941. Different approaches to the problem of the organization and localization of verbal functions as well as to the understanding of mechanisms of aphasia and principles of aphasia rehabilitation are discussed. Comparisons with European and North American contributions and with contributions from later Russian writing (e.g., Luria's period) are presented to demonstrate their interconnections in shaping the course of Russian aphasiology.