Multilevel analysis in CSCL Research

Janssen, J., Erkens, G., Kirschner, P. A., & Kanselaar, G. (2011). Multilevel analysis in CSCL research. In S. Puntambekar, G. Erkens, & C. Hmelo-Silver (Eds.), Analyzing interactions in CSCL: Methods, approaches and issues (pp. 187-205). New York: Springer. doi:10.1007/978-1-4419-7710-6_9CSCL researchers are often interested in the processes that unfold between learners in online learning environments and the outcomes that stem from these interactions. However, studying collaborative learning processes is not an easy task. Researchers have to make quite a few methodological decisions such as how to study the collaborative process itself (e.g., develop a coding scheme or a questionnaire), on the appropriate unit of analysis (e.g., the individual or the group), and which statistical technique to use (e.g., descriptive statistics, analysis of variance, correlation analysis). Recently, several researchers have turned to multilevel analysis (MLA) to answer their research questions (e.g., Cress, 2008; De Wever, Van Keer, Schellens, & Valcke, 2007; Dewiyanti, Brand-Gruwel, Jochems, & Broers, 2007; Schellens, Van Keer, & Valcke, 2005; Strijbos, Martens, Jochems, & Broers, 2004; Stylianou-Georgiou, Papanastasiou, & Puntambekar, chapter #). However, CSCL studies that apply MLA analysis still remain relatively scarce. Instead, many CSCL researchers continue to use ‘traditional’ statistical techniques (e.g., analysis of variance, regression analysis), although these techniques may not be appropriate for what is being studied. An important aim of this chapter is therefore to explain why MLA is often necessary to correctly answer the questions CSCL researchers address. Furthermore, we wish to highlight the consequences of failing to use MLA when this is called for, using data from our own studies

Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.Animal science

Caractérisation des écoulements d'air dans une semie remorque chargée de carcasses de viande

3rd International Conference on Food and Biosystems Engineering, Rhodes, GRC, 01-/06/2017 - 04/06/2017International audienceAfter slaughtering, pork carcasses should be cooled down as fast as possible to reach a core temperature of 7°C (current requirement in European regulation) before transport in order to inhibit the growth of spoilage and pathogen microorganisms. To reach this temperature, carcasses are usually loaded into chiller rooms (15-20 hours) where the rate of cooling is controlled. To reduce the logistic time from slaughter house to cutting plant, a solution is proposed by loading the product into a trailer at core temperatures higher than 7°C. However, we have to assess that such a practice will not lead to a sanitary risk when applied to real scenario. In order to answer this issue, the first step will be to study the airflow characteristics within a trailer filled with pre-chilled pork carcasses.The objective of this study is to investigate experimentally the air velocity distribution in a reduced scale trailer filled with reduced scale carcass models under isothermal conditions. The 215 carcass models were made of polyurethane foam using a mold obtained by 3D printing based on X-ray scanner of a real carcass. The Reynold number in the experimental device is the same as in a real trailer (Re ~1.

Muscle-only versus chimeric musculocutaneous gastrocnemius pedicled flap in complex orthoplastic reconstructions of the knee region: A retrospective study.

The knee region represents a challenging area of soft tissue reconstruction. Specifically, in the context of total knee arthroplasty (TKA) or following high-energy trauma with fractures and hardware fixation, soft tissue defects can expose critical structures such as joint, bone or tendon, besides the implant/plates themselves, with dramatic consequences in terms of postoperative infection and hardware contamination. A retrospective study was conducted on a prospectively maintained database from January 2016 to February 2021. Inclusion criteria involved all patients who underwent an implant-associated infection of the knee and upper third of the leg coupled with a soft tissue reconstruction (STR) using the traditional gastrocnemius muscle (GM) pedicled flap or the chimeric GM-MSAP (medial sural artery perforator) flap. Thirty-eight patients were included (group A, GM flap, 22 patients; group B, chimeric GM-MSAP flap, 16 patients). No statistically significant differences were detected in terms of age, comorbidities, defect size, follow-up, and flap complications. A statistically significant difference was seen among the groups in terms of successful flap re-raise (required because of a persistent infection of the implant or in a two-stage procedure setting, including the use of a cemented spacer) in favour of the GM-MSAP group. The chimeric GM-MSAP, being safer to reraise if required, can be a significantly more powerful tool in those cases in which a two-stage procedure is planned or when there is a high probability for secondary intervention need, reducing the need to convert to either free flap coverage or amputation

Lower limb soft tissue reconstruction using free ALT flaps: multimodal parameter analysis to predict the level of spontaneous reinnervation.

This work aims to assess lower limb free flaps spontaneous sensory recovery by comparing and analyzing a single standardized reconstructive procedure, namely the free noninnervated anterolateral thigh (ALT) flap in order to evaluate which flap or patient-related factors may predict flap reinnervation. Between January 2010 and March 2018 all nonreinnervated ALT flaps for lower limb coverage performed at our institution were screened. We excluded from the study flaps with less than 18 months of follow-up time, neurotized flaps, and those from patients who missed the last follow up. Sensory modalities that were evaluated included the two-point discrimination (2PD) test, measured in mm; and the Semmes-Weinstein monofilament (SWM) test, measured in gram. The sensory parameter results were compared and analyzed according to flap size (two groups; <160 cm <sup>2</sup> vs. > 160 cm <sup>2</sup> ), and post-op time of testing (two groups; <18-28 months vs. > 28 months). Twenty-one ALT free flaps were finally retained by this study. Our findings showed that flaps of smaller surface area showed a significantly better return in sensory discrimination 2PD and in sensory cutaneous pressure perception SWM testing. This work establishes for the first time some key quantitative data that can help predict free flap spontaneous reinnervation outcomes when using the same ALT flap. In our series, flaps surface remains the main discriminant value for a better sensory recovery

Lower limb soft tissue reconstruction using free ALT flaps: multimodal parameter analysis to predict the level of spontaneous reinnervation

Introduction: This work aims to assess lower limb free flaps spontaneous sensory recovery by comparing and analyzing a single standardized reconstructive procedure, namely the free noninnervated anterolateral thigh (ALT) flap in order to evaluate which flap or patient-related factors may predict flap reinnervation. Methods: Between January 2010 and March 2018 all nonreinnervated ALT flaps for lower limb coverage performed at our institution were screened. We excluded from the study flaps with less than 18 months of follow-up time, neurotized flaps, and those from patients who missed the last follow up. Sensory modalities that were evaluated included the two-point discrimination (2PD) test, measured in mm; and the Semmes–Weinstein monofilament (SWM) test, measured in gram. The sensory parameter results were compared and analyzed according to flap size (two groups; <160 cm2 vs. > 160 cm2), and post-op time of testing (two groups; <18–28 months vs. > 28 months). Results: Twenty-one ALT free flaps were finally retained by this study. Our findings showed that flaps of smaller surface area showed a significantly better return in sensory discrimination 2PD and in sensory cutaneous pressure perception SWM testing. Conclusion: This work establishes for the first time some key quantitative data that can help predict free flap spontaneous reinnervation outcomes when using the same ALT flap. In our series, flaps surface remains the main discriminant value for a better sensory recovery