Patient-specific spine models. Part 1: Finite element analysis of the lumbar intervertebral disc--a material sensitivity study

If patient-specific finite element models of the spine could be developed, they would offer enormous opportunities in the diagnosis and management of back problems. Several generic models have been developed in the past, but there has been very little detailed examination of the sensitivity of these models' characteristics to the input parameters. This relationship must be thoroughly understood if representative patient-specific models are to be realized and used with confidence. In particular, the performance of the intervertebral discs are central to any spine model and need detailed investigation first. A generic non-linear model of an intervertebral disc was developed and subjected to compressive, flexion and torsional loading regimes. The effects of both material and geometric non-linearities were investigated for the three loading schemes and the results compared with experimental data. The basic material properties of the fibres, annulus and nucleus were then varied and the effects on the stiffness, annulus bulge and annulus stresses analysed. The results showed that the non-linear geometry assumption had a significant effect on the compression characteristics, whereas the non-linear material option did not. In contrast, the material non-linearity was more important for the flexural and torsional loading schemes. Thus, the inclusion of non-linear material and geometry analysis options in finite element models of intervertebral discs is necessary to predict in vivo load-deflection characteristics accurately. When the influence of the material properties was examined in detail, it was found that the fibre properties did not have a significant effect on the compressive stiffness of the disc but did affect the flexural and torsional stiffnesses by up to +/-20 per cent. All loading modes were sensitive to the annulus properties with stiffnesses varying by up to +/-16 per cent. The model also revealed that for a particular compressive deformation or flexural or torsional rotation, the disc bulge was not sensitive to any of the material properties over the range of properties considered. The annulus stresses did differ significantly as the material properties were varied (up to 70 per cent under a compressive load and 60 per cent during disc flexion).     

Toward Improved Statistical Reporting in the Journal of Consulting and Clinical Psychology.

Philip Kendall's (1997) editorial encouraged authors in the Journal of Consulting and Clinical Psychology (JCCP) to report effect sizes and clinical significance. The present authors assessed the influence of that editorial--and other American Psychological Association initiatives to improve statistical practices--by examining 239 JCCP articles published from 1993 to 2001. For analysis of variance, reporting of means and standardized effect sizes increased over that period, but the rate of effect size reporting for other types of analyses surveyed remained low. Confidence interval reporting increased little, reaching 17% in 2001. By 2001, the percentage of articles considering clinical (not only statistical) significance was 40%, compared with 36% in 1996. In a follow-up survey of JCCP authors (N=62), many expressed positive attitudes toward statistical reform. Substantially improving statistical practices may require stricter editorial policies and further guidance for authors on reporting and interpreting measures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transformational leadership and psychological well-being: The mediating role of meaningful work.

Two studies investigated the relationship between transformational leadership, the meaning that individuals ascribe to their work, and their psychological well-being. In Study 1, the perceptions of meaningful work partially mediated the relationship between transformational leadership and positive affective well-being in a sample of Canadian health care workers (N=319). In Study 2, the meaning that a separate sample of service workers (N=146) ascribed to their work fully mediated the relationship between transformational leadership and psychological well-being, after controlling for humanistic work beliefs. Overall, these results support and add to the range of positive mental health effects associated with transformational leadership and are suggestive of interventions that organizations can make to improve well-being of workers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biomimetics: its practice and theory.

Biomimetics, a name coined by Otto Schmitt in the 1950s for the transfer of ideas and analogues from biology to technology, has produced some significant and successful devices and concepts in the past 50 years, but is still empirical. We show that TRIZ, the Russian system of problem solving, can be adapted to illuminate and manipulate this process of transfer. Analysis using TRIZ shows that there is only 12% similarity between biology and technology in the principles which solutions to problems illustrate, and while technology solves problems largely by manipulating usage of energy, biology uses information and structure, two factors largely ignored by technology.     

Xeroradiographic tomography of the larynx

Adequate assessment of disease extent is vital for tumour control in the larynx. Xeroradiography using a tomographic technique was investigated. A preliminary study was carried out to assess the optimum technique and exposure. It was also found that the radiation dose to the skin, although just over twice that for film, could be halved by the removal of the secondary radiation grid. Images of 24 patients treated were assessed for soft tissue and bony detail, and it was found that the xerotomograms were beneficial to the radiotherapy planning of the treatment volume of laryngeal and related neck carcinomas.     

Selective recall for personally relevant communications.

Used 2 experiments to test whether people display a recall bias for supportive over refutive information. While previous work has used broad social attitudes, the present research investigated recall for communications relevant to Ss' behavior. In Exp I, 15 smokers, 36 nonsmokers, and 24 ex-smokers read and recalled information related to smoking. In Exp II, 28 seatbelt wearers, 18 occasional wearers, and 15 nonwearers read and recalled pro-seatbelt material. As predicted, in both experiments Ss' behavior significantly affected their recall of information: Nonsmokers recalled more anti-smoking material than smokers, and seatbelt wearers recalled more pro-seatbelt information than nonwearers. There were no significant effects on any measures when Ss in Exp I were divided into seatbelt wearers and nonwearers and when Ss in Exp II were divided into smokers and nonsmokers. Thus, Ss were selective only on the communication relative to their own behavior. (French abstract) (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pleasant events, activity schedules, and depressions.

Instructed 3 groups of 10 undergraduates each (depressed, psychiatric controls, and normal controls) to rate their moods and indicate the number of pleasant activities engaged in each day for 30 days. A significant association between mood and pleasant activities was found. There were large individual differences in regard to the magnitude of the correlation between mood and activity, but differences between groups failed to attain statistical significance. Results are interpreted as consistent with the major tenet of the behavioral theory of depression, i.e., that there is an association between rate of positive reinforcement and intensity of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personal self-disclosure: Expectancy and situational effects.

96 male undergraduates, selected from a pool of 169 because of their high or low scores on the Jourard Self-Disclosure Questionnaire (JSDQ), were randomly assigned to 1 of 2 conditions of specific expectancy, in which they were told that they would find it either easy or difficult to self-disclose to a stranger interviewer, and 1 of 3 conditions of interviewers' behavior (personal, impersonal, or no disclosure). The JSDQ, scored for anticipated self-disclosure but not for recalled self-disclosure, predicted observed performance. The specific expectancy manipulation and the intimacy level of topics also had significant effects on self-disclosure. A 3-way interaction between generalized and specific expectancy and topic intimacy was also found. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory: A comparison between frontal and nonfrontal right- and left-hemisphere brain-damaged patients.

Tested 2 groups of brain-damaged patients (n = 60 and 17) and 2 groups of controls (n = 28 and 7) on 4 different short-term memory tasks, each designed to measure the amount of information registered (0-sec delay recall) and retained after a delay of 10 sec. in 1 of 3 (visual, auditory, and kinesthetic) sensory modalities, using a variety of stimulus materials. Differences between the brain-damaged and control groups were largely due to the reduced capacity of the brain damaged to register information. Ss with anterior cerebral damage did more poorly than Ss with posterior damage on both visual and auditory short-term memory tasks. No significant differences were found between right- and left-hemisphere-damaged Ss. (26 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quadratic behavior of fiber Bragg grating temperature coefficients

We describe the characterization of the temperature and strain responses of fiber Bragg grating sensors by use of an interferometric interrogation technique to provide an absolute measurement of the grating wavelength. The fiber Bragg grating temperature response was found to be nonlinear over the temperature range -70 degrees C to 80 degrees C. The nonlinearity was observed to be a quadratic function of temperature, arising from the linear dependence on temperature of the thermo-optic coefficient of silica glass over this range, and is in good agreement with a theoretical model.