Notochord grafts do not suppress formation of neural crest cells or commissural neurons

Grafting experiments previously have established that the notochord affects dorsoventral polarity of the neural tube by inducing the formation of ventral structures such as motor neurons and the floor plate. Here, we examine if the notochord inhibits formation of dorsal structures by grafting a notochord within or adjacent to the dorsal neural tube prior to or shortly after tube closure. In all cases, neural crest cells emigrated from the neural tube adjacent to the ectopic notochord. When analyzed at stages after ganglion formation, the dorsal root ganglia appeared reduced in size and shifted in position in embryos receiving grafts. Another dorsal cell type, commissural neurons, identified by CRABP and neurofilament immunoreactivity, differentiated in the vicinity of the ectopic notochord. Numerous neuronal cell bodies and axonal processes were observed within the induced, but not endogenous, floor plate 1 to 2 days after implantation but appeared to be cleared with time. These results suggest that dorsally implanted notochords cannot prevent the formation of neural crest cells or commissural neurons, but can alter the size and position of neural crest-derived dorsal root ganglia

Cranial and trunk neural crest cells use different mechanisms for attachment to extracellular matrices

We have used a quantitative cell attachment assay to compare the interactions of cranial and trunk neural crest cells with the extracellular matrix (ECM) molecules fibronectin, laminin and collagen types I and IV. Antibodies to the β_1 subunit of integrin inhibited attachment under all conditions tested, suggesting that integrins mediate neural crest cell interactions with these ECM molecules. The HNK-1 antibody against a surface carbohydrate epitope under certain conditions inhibited both cranial and trunk neural crest cell attachment to laminin, but not to fibronectin. An antiserum to α_1 intergrin inhibited attachment of trunk, but not cranial, neural crest cells to laminin and collagen type I, though interactions with fibronectin or collagen type IV were unaffected. The surface properties of trunk and cranial neural crest cells differed in several ways. First, trunk neural crest cells attached to collagen types I and IV, but cranial neural crest cells did not. Second, their divalent cation requirements for attachment to ECM molecules differed. For fibronectin substrata, trunk neural crest cells required divalent cations for attachment, whereas cranial neural crest cells bound in the absence of divalent cations. However, cranial neural crest cells lost this cation-independent attachment after a few days of culture. For laminin substrata, trunk cells used two integrins, one divalent cation-dependent and the other divalent cation-independent (Lallier, T. E. and Bronner-Fraser, M. (1991) Development 113, 1069–1081). In contrast, cranial neural crest cells attached to laminin using a single, divalent cation-dependent receptor system. Immunoprecipitations and immunoblots of surface labelled neural crest cells with HNK-1, α_1 integrin and β_1 integrin antibodies suggest that cranial and trunk neural crest cells possess biochemically distinct integrins. Our results demonstrate that cranial and trunk cells differ in their mechanisms of adhesion to selected ECM components, suggesting that they are non-overlapping populations of cells with regard to their adhesive properties

Applying Quadratic Scoring Rule transparently in multiple choice settings: A note

The quadratic scoring rule (QSR) is often used to guarantee an incentive compatible elicitation of subjective probabilities over events. Experimentalists have regularly not been able to ensure that subjects fully comprehend the consequences of their actions on payoffs given the rules of the games. In this note, we present a procedure that allows the transparent use of the QSR even in multiple-choice scenarios. For that purpose, two methodological means are applied: an alternative representation of the score and a short learning period to familiarize subjects with the payoff mechanism. The results suggest that both means were necessary and successful in facilitating subjects' understanding of the rule.Quadratic scoring rule, experimental methodology, experimental design

Applying Quadratic Scoring Rule transparently in multiple choice settings: A note

The quadratic scoring rule (QSR) is often used to guarantee an incentive compatible elicitation of subjective probabilities over events. Experimentalists have regularly not been able to ensure that subjects fully comprehend the consequences of their actions on payoffs given the rules of the games. In this note, we present a procedure that allows the transparent use of the QSR even in multiple-choice scenarios. For that purpose, two methodological means are applied: an alternative representation of the score and a short learning period to familiarize subjects with the payoff mechanism. The results suggest that both means were necessary and successful in facilitating subjects’ understanding of the rule.quadratic scoring rule, belief elicitation, saliency, experiment

Standardizing Evaluation Methods for Simulation

Background: Evidence suggests that student registered nurse anesthetists (SRNAs) benefit from simulation in the educational curriculum (Turcato, Roberson, & Covert, 2008). When simulation is implemented into coursework, it is important to evaluate student learning and perceptions (Adamson & Kardong-Edgren, 2012), however, there are few standardized instruments available (Adamson et al., 2012; Doolan et al., 2016). Objectives: The goal of this project was to provide the foundation for standardizing simulation evaluation tools within a midwestern university’s school of nurse anesthesia. Methods: A presentation on the Value Analysis Model was developed through extensive use of the literature and collaboration with a content expert. As participants were walked through a fictional scenario, they learned how to write evaluations, interpret data, and calculate return on investment. The presentation was attended by simulation-focused faculty from the university, anesthesia students, and members of the St. Louis Simulation Interest Group. To promote project sustainability, a binder with information and resources on the Value Analysis Model was given to simulation faculty at the university for future use. Results: Surveys were designed using the Value Analysis Model and responses were kept anonymous. Participants agreed that the material presented was important, relevant to their work, useful, and applicable. Participants also agreed that they gained a basic knowledge of the topic and how to apply it to simulation. Conclusions: This project served as the first step toward developing standardized evaluation instruments for the university department of nurse anesthesia

Effect of Aging Time and Boron Addition on the Properties of 9-12% Cr Power Plant Steels - outcomes from Different Experimental Investigations

The relation between the aging time and the mechanical properties of the investigated steels was demonstrated graphically as a result of an experimental work in this paper. The effect of trace boron in steels, especially the influence of boron on microstructure and properties of 9-12% Cr steels were also summarized. Three alloys with and without boron of 9% Cr steels were prepared. The specimens prepared for testing were aged at 20 oC and 650 oC for time range of 3000 to 10000 hrs. Concerning the effect of boron addition to the 9-12% Cr steels, some results of recent investigation studies by other researchers were also mentioned in this paper for more information about the role of this alloying element in improving of high alloyed chromium steels