Toward a script theory of guidance in computer-supported collaborative learning

This article presents an outline of a script theory of guidance for computer-supported collaborative learning (CSCL). With its four types of components of internal and external scripts (play, scene, role, and scriptlet) and seven principles, this theory addresses the question how CSCL practices are shaped by dynamically re-configured internal collaboration scripts of the participating learners. Furthermore, it explains how internal collaboration scripts develop through participation in CSCL practices. It emphasizes the importance of active application of subject matter knowledge in CSCL practices, and it prioritizes transactive over non-transactive forms of knowledge application in order to facilitate learning. Further, the theory explains how external collaboration scripts modify CSCL practices and how they influence the development of internal collaboration scripts. The principles specify an optimal scaffolding level for external collaboration scripts and allow for the formulation of hypotheses about the fading of external collaboration scripts. Finally, the article points towards conceptual challenges and future research questions

Fast Registration of Cardiac Perfusion MRI

This abstract presents a novel method for registration of cardiac perfusion MRI sequences. By performing complex analyses of variance and clustering in an annotated training set off-line, our method provides real-time segmentation in an on-line setting. This renders the method feasible for live motion-compensation in MR scanners. Changes in image intensity during the bolus passage are modelled by an Active Appearance Model augmented with a cluster analysis of the training set. Preliminary validation carried out using five subjects showed acceptable segmentation accuracy produced very rapidly (below 40 ms per image)

Electrostatic colloid-membrane complexation

We investigate numerically and on the scaling level the adsorption of a charged colloid on an oppositely charged flexible membrane. We show that the long ranged character of the electrostatic interaction leads to a wrapping reentrance of the complex as the salt concentration is varied. The membrane wrapping depends on the size of the colloid and on the salt concentration and only for intermediate salt concentration and colloid sizes we find full wrapping. From the scaling model we derive simple relations for the phase boundaries between the different states of the complex, which agree well with the numerical minimization of the free energy.Comment: 7 page, 11 figure

Risk of Cutaneous Squamous Cell Carcinoma Development in Renal Transplant Recipients Is Independent of TMC/EVER Alterations

Renal transplant recipients (RTRs) have an increased risk of developing nonmelanoma skin cancer, mainly cutaneous squamous cell carcinoma (cSCC). Two genes (TMC6/EVER1 and TMC8/EVER2), mutated in epidermodysplasia verruciformis (EV) patients with an increased risk of cSCC development, contain numerous single-nucleotide polymorphisms (SNPs).; To evaluate the effect of SNPs in both TMC/EVER genes on the different susceptibilities of RTRs to cSCC.; We determined the occurrence of cSCC in 105 RTRs who were transplanted at least 7 years previously and investigated the frequency of 26 SNPs within both TMC/EVER genes in severely affected (n = 16) as well as in nonaffected RTRs (n = 25).; Our data did not indicate a significant association between any SNP genotype and risk of cSCC development in RTRs.; To clarify the correlation between SNPs in both TMC genes and cSCC development in RTRs, integrated investigations of large cohorts including both RTRs and immunocompetent individuals with consideration of cSCC status, SNP genotype and human papillomavirus status might be necessary

Risk of Cutaneous Squamous Cell Carcinoma Development in Renal Transplant Recipients Is Independent of TMC/EVER Alterations

Renal transplant recipients (RTRs) have an increased risk of developing nonmelanoma skin cancer, mainly cutaneous squamous cell carcinoma (cSCC). Two genes (TMC6/EVER1 and TMC8/EVER2), mutated in epidermodysplasia verruciformis (EV) patients with an increased risk of cSCC development, contain numerous single-nucleotide polymorphisms (SNPs).; To evaluate the effect of SNPs in both TMC/EVER genes on the different susceptibilities of RTRs to cSCC.; We determined the occurrence of cSCC in 105 RTRs who were transplanted at least 7 years previously and investigated the frequency of 26 SNPs within both TMC/EVER genes in severely affected (n = 16) as well as in nonaffected RTRs (n = 25).; Our data did not indicate a significant association between any SNP genotype and risk of cSCC development in RTRs.; To clarify the correlation between SNPs in both TMC genes and cSCC development in RTRs, integrated investigations of large cohorts including both RTRs and immunocompetent individuals with consideration of cSCC status, SNP genotype and human papillomavirus status might be necessary