The filament forming reactions of vimentin tetramers studied in a serial-inlet microflow device by small angle x-ray scattering

The structural organization of metazoan cells and their shape are established through the coordinated interaction of a composite network consisting of three individual filament systems, collectively termed the cytoskeleton. Specifically, microtubules and actin filaments, which assemble from monomeric globular proteins, provide polar structures that serve motor proteins as tracks. In contrast, intermediate filaments (IFs) assemble from highly charged, extended coiled coils in a hierarchical assembly mechanism of lateral and longitudinal interaction steps into non-polar structures. IF proteins are expressed in a distinctly tissue-specific way and thereby serve to generate the precise plasticity of the respective cells and tissues. Accordingly, in the cell, numerous parameters such as pH and salt concentration are adjusted such that the generation of functional networks is ensured. Here, we transfer the problem for the mesenchymal IF protein vimentin to an in vitro setting and combine small angle x-ray scattering with microfluidics and finite element method simulations. Our approach is adapted to resolve the early assembly steps, which take place in the sub-second to second range. In particular, we reveal the influence of ion species and concentrations on the assembly. By tuning the flow rates and thus concentration profiles, we find a minimal critical salt concentration for the initiation of the assembly. Furthermore, our analysis of the surface sensitive Porod regime in the x-ray data reveals that the formation of first assembly intermediates, so-called unit length filaments, is not a one-step reaction but consists of distinct consecutive lateral association steps followed by radial compaction as well as smoothening of the surface of the full-width filament.     

Social Support,Psychological Well-being,and Health Among the Elderly

This article is based on the influence that participation in the Third Age University Program has on the health and well-being of the elderly and with the mediation of social support. The data were obtained from a longitudinal study of 147 elderly students of the Third Age University of Seville (Spain). The hypothesis was that the elders who belong to the program would have, as a consequence of their participation in it, better health, well-being, and social support. The results revealed the influence that social support exercises on well-being and, as a result, upon health.     

Academic achievement among a sample of youth in foster care: The role of school connectedness

Research shows that youth in foster care experience poor academic performance and disciplinary actions in school more frequently than do non-foster care youth. The purpose of this cross-sectional study was to further examine youth in foster care and the relationship between individual/intrapersonal factors (future orientation and school connectedness) and exosystem factors (number of placement and school moves) and academic performance (grades) and disciplinary referrals among 363 youth (9–11 years of age; males = 52.9%). Controlling for key variables, hierarchical linear regression analysis was utilized to understand how well students' school connectedness, future outlook, number of placement changes, and number of school moves predicted academic and disciplinary outcomes. Beyond the variance explained by control variables, school connectedness made a significant contribution to this model. Results are discussed in the context of implementing interventions that foster school connectedness among this vulnerable population.     

A synthesis of research on effectiveness of school-based drug prevention programmes / Claves de eficacia de los programas de prevención de consumo de sustancias en el contexto escolar: una meta-revisión

Abstract

Relevant information on effectiveness of school-based drug prevention programmes is available. Despite this, there is still contradictory evidence that makes it necessary to continue to shed light on this issue. Based on a synthesis research method, the aim of this study was to determine the relevant variables that enhance the efficacy of these programmes and to determine the weight of their empirical evidence. Furthermore, several features of the evaluation designs whose variables had been proven effective were examined. A systematic review of periodical literature was conducted, which led us to extract 1,622 papers, of which 17 studies were analysed. An in-depth analysis of these publications led us to identify 29 key variables associated with the efficacy of the programme, which were ranked according to the weight of their empirical evidence. Moreover, the characteristics of the studies included in the review highlighted the need to improve the rigorousness and quality of the evaluation designs in this field.     

Representación y magnitud de los sumandos en la resolución de problemas aditivos

Resumen

Se estudia la incidencia del nivel de abstracción y de la magnitud de los sumandos en la resolución de tareas aditivas elementales. Para ello, dos muestras de niños de 5 a 7 años pasaron diferentes pruebas. Los resultados muestran en general que los factores edad, modo de representación y el tamaño y posición de los sumandos son estadísticamente significativos. Más en conaeto, los niños pequeños son especialmente sensibles al grado de abstracción de los sumandos, mientras que el grupo de los mayores se ve afectado principalmente por el tercer factor. Por otra parte, el repertorio de estrategias empleado es pobre en los preescolares y variado en los escolares.     

Writing at university: are we on the same page? / Escribir en la universidad: ¿nos entendemos?

Abstract

This study seeks to analyse the characteristics and functions that students and faculty attribute to written genres in Spanish universities, to what extent these representations are shared by both groups, and how they contribute to the construction of disciplinary knowledge in Spanish higher education. Accordingly, we classified students’ and teachers’ responses into 12 genre families grouped into five functions: Disciplinary Knowledge (DK), Critical Analysis (AC), Personal Reflection (PR), Research (R) and Professional Practice (PP). In terms of functions, demonstration of disciplinary knowledge appeared as the most frequently mentioned goal for both groups, whereas the genres targeted at research were the least frequent ones, along with the genres used for personal reflection. The most common genre family for both groups was Explanation, which was linked to demonstration of knowledge acquired in the discipline.     

Camila,the earth,and the sun: Constructing an idea as shared intellectual property

Recent research has challenged traditional assumptions that scientific practice and knowledge are essentially individual accomplishments, highlighting instead the social nature of scientific practices, and the co‐construction of scientific knowledge. Similarly, new research paradigms for studying learning go beyond focusing on what is “in the head” of individual students, to study collective practices, distributed cognition, and emergent understandings of groups. These developments require new tools for assessing what it means to learn to “think like a scientist.” Toward this goal, the present case study analyzes the discourse of a 6th‐grade class discussing one student's explanation for seasonal variations in daylight hours. The analysis identifies discourse moves that map to disciplinary practices of the social construction of science knowledge, including (1) beginning an explanation by reviewing the community's shared assumptions; (2) referencing peers' work as warrants for an argument; and (3) building from isolated ideas, attributed to individuals, toward a coherent situation model, attributed to the community. The study then identifies discourse moves through which the proposed explanation was taken up and developed by the group, including (4) using multiple shared representations; (5) leveraging peers' language to clarify ideas; and (6) negotiating language and representations for new, shared explanations. Implications of this case for rethinking instruction, assessment, and classroom research are explored. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 47:619–642, 2010     

Do teachers’ conflicting testimonies influence children’s decisions about unconventional rules of counting?

This study addresses the influence of schoolteachers’ testimonies on children’s conceptions about unconventional correct counts or pseudoerrors. A total of 158 kindergarteners and second graders were individually interviewed: Fifty children participated in the baseline group (to determine their judgments about pseudoerrors without the presence of informants), and 108 children participated in the experimental group. There were two sessions—2 weeks apart—for the experimental group: in session 1, children faced the conflicting claims provided by three teachers vs. a dissident teacher about the correctness of different pseudoerrors made by the characters of a computer game. The participants had to decide which of the informants was right, providing a rationale for their choice. In session 2, children evaluated the same types of pseudoerrors but in absence of informants (similar to the baseline group procedure). We assessed the relative influence of the majority, and whether the presentation of teachers’ controversial judgments improved children’s understanding of counting. The findings revealed that children’s own ideas prevailed over the pressure of the majority: at both ages, children tended to endorse claims that considered pseudoerrors as incorrect counts, regardless of the source of information (majority or dissenter), and their tendency to reject pseudoerrors remained firm in session 2. Overall, results from the experimental and the baseline groups suggest that children’s adherence to the conventional rules of counting is strong and little susceptible to influence and revision. We discuss the educational implications of these findings as well as the limitations of the experimental paradigm used in this and other studies in the field of testimony.