The organization of transactions research with the Trust and Tracing Game

This paper presents empirical results of research on the influence of social aspects on the organization of transactions in the domain of chains and networks. The research method used was a gaming simulation called the Trust and Tracing game in which participants trade commodity goods with a hidden quality attribute. Previous sessions of this gaming simulation identified a list of variables for further investigation (Meijer et al., 2006). The use of gaming simulation as data gathering tool for quantitative research in supply chains and networks is a proof-of-principle. This paper shows results from 27 newly conducted sessions and previously unused data from 3 older sessions. Tests confirmed the use of network and market modes of organization. Pre-existing social relations influenced the course of the action in the sessions. Being socially embedded was not beneficial for the score on the performance indicators money and points. The hypothesized reduction in measurable transaction costs when there was high trust between the participants could not be found. Further analysis revealed that participants are able to suspect cheats in a session based on other factors than tracing. Testing hypotheses with data gathered in a gaming simulation proved feasible. Experiences with the methodology used are discusse

Flexible (Polyactive®) versus rigid (hydroxyapatite) dental implants

In a beagle dog study, the peri-implant bone changes around flexible (Polyactive®) and rigid hydroxyapatite (HA) implants were investigated radiographically by quantitative digital subtraction analysis and by assessment of marginal bone height, with the aid of a computerized method. A loss of approximately 1 mm of marginal bone height was observed for both the dense Polyactive and the HA implants, after 6 months of loading. This value appeared to be stable from 12 weeks of loading onward. Along the total length of the implant during the first 6 weeks of loading, both the flexible (dense Polyactive) and the rigid (HA) implants showed a decrease in density. However, after this 6-week period, the bone density around the implants increased, and after 18 weeks the original bone density was reached. The flexible Polyactive implants provoked less decrease in density than the rigid HA implants, although not to a statistically significant level. This finding sustains the hypothesis that flexible implant materials may transfer stresses to the surrounding bone more favorably

A Multi Criteria Decision Analytic (MCDA) approach to combining evidence and patient preferences for cancer prevention and treatment: an application to prostate cancer screening

A 72-year-old man, edentulous in the maxilla for 20 years, presented himself at his dentist in 2006 with complaints concerning retention of his upper denture. The placement of implants was only possible if bone augmentation was undertaken; this was definitively rejected by the man. As an alternative, Muchor anchors were placed, but these did not provide an adequate solution to the retention problem. In the end, 2 palatal implants were placed, with magnetic anchoring. One year later, the man was very satisfied with this solution

Ectopic bone formation in bone marrow stem cell seeded calcium phosphate scaffolds as compared to autograft and (cell seeded) allograft

Improvements to current therapeutic strategies are needed for the treatment of skeletal defects. Bone tissue engineering offers potential advantages to these strategies. In this study, ectopic bone formation in a range of scaffolds was assessed. Vital autograft and devitalised allograft served as controls and the experimental groups comprised autologous bone marrow derived stem cell seeded allograft, biphasic calcium phosphate (BCP) and tricalcium phosphate (TCP), respectively. All implants were implanted in the back muscle of adult Dutch milk goats for 12 weeks. Micro-computed tomography (µCT) analysis and histomorphometry was performed to evaluate and quantify ectopic bone formation. In good agreement, both µCT and histomorphometric analysis demonstrated a significant increase in bone formation by cell-seeded calcium phosphate scaffolds as compared to the autograft, allograft and cell-seeded allograft implants. An extensive resorption of the autograft, allograft and cell-seeded allograft implants was observed by histology and confirmed by histomorphometry. Cell-seeded TCP implants also showed distinct signs of degradation with histomorphometry and µCT, while the degradation of the cell-seeded BCP implants was negligible. These results indicate that cell-seeded calcium phosphate scaffolds are superior to autograft, allograft or cell-seeded allograft in terms of bone formation at ectopic implantation sites. In addition, the usefulness of µCT for the efficient and non-destructive analysis of mineralised bone and calcium phosphate scaffold was demonstrated

Experienced emotional burden in caregivers: psychometric properties of the Involvement Evaluation Questionnaire in caregivers of brain injured patients

Objective: To examine the psychometric properties (internal consistency, discriminant validity, and responsiveness) of the Involvement Evaluation Questionnaire for Brain Injury measuring emotional burden in caregivers of patients with chronic acquired brain injury. Design: Inception cohort study. Subjects: Caregivers of chronic acquired brain injury patients. Main measures: Besides the Involvement Evaluation Questionnaire for Brain Injury, the Family Assessment Device and the General Health Questionnaire were used. Methods: Ninety-eight caregivers filled out all questionnaires, of which 41 caregivers did this twice, before and after the persons they cared for had started a residential community reintegration programme. Cronbach's alpha and Intra class Correlation Coefficient were calculated for internal consistency. Pearson correlation coefficients were used for discriminant validity and Intra class Correlation Coefficient and Cohen's d were calculated to determine responsiveness. Results: The internal consistency of the Involvement Evaluation Questionnaire for Brain Injury was good (alpha = 0.73-0.84; Intra class Correlation Coefficient = 0.69-0.76). As expected, low correlations were found between the Involvement Evaluation Questionnaire for Brain Injury and either the General Health Questionnaire (r = 0.11-0.40) or the Family Assessment Device subscales (r = -0.29-0.19). Regarding responsiveness of the Involvement Evaluation Questionnaire for Brain Injury, a moderate effect size was found (Cohen's d = 0.36) while the Intra class Correlation Coefficient was good (0.80). Conclusions: The Involvement Evaluation Questionnaire for Brain Injury measures the experienced emotional burden in caregivers of patients with chronic acquired brain injury and seems to be a promising new instrument with good internal consistency, discriminant validity and responsiveness