Microfluidic devices fitted with “flowver” paper pumps generate steady,tunable gradients for extended observation of chemotactic cell migration

Microfluidics approaches have gained popularity in the field of directed cell migration, enabling control of the extracellular environment and integration with live-cell microscopy; however, technical hurdles remain. Among the challenges are the stability and predictability of the environment, which are especially critical for the observation of fibroblasts and other slow-moving cells. Such experiments require several hours and are typically plagued by the introduction of bubbles and other disturbances that naturally arise in standard microfluidics protocols. Here, we report on the development of a passive pumping strategy, driven by the high capillary pressure and evaporative capacity of paper, and its application to study fibroblast chemotaxis. The paper pumps—flowvers (flow + clover)—are inexpensive, compact, and scalable, and they allow nearly bubble-free operation, with a predictable volumetric flow rate on the order of μl/min, for several hours. To demonstrate the utility of this approach, we combined the flowver pumping strategy with a Y-junction microfluidic device to generate a chemoattractant gradient landscape that is both stable (6+ h) and predictable (by finite-element modeling calculations). Integrated with fluorescence microscopy, we were able to recapitulate previous, live-cell imaging studies of fibroblast chemotaxis to platelet derived growth factor (PDGF), with an order-of-magnitude gain in throughput. The increased throughput of single-cell analysis allowed us to more precisely define PDGF gradient conditions conducive for chemotaxis; we were also able to interpret how the orientation of signaling through the phosphoinositide 3-kinase pathway affects the cells’ sensing of and response to conducive gradients.     

Bewegungsverhältnisse in der Gesundheitsförderung

Improving environments for physical activity is a fundamental goal of health sports. Both considerations in sport science as well as practical guidelines by sport associations and sickness funds build upon that. However, currently there is neither a theory-based concept nor a systematic operationalisation of that concept. In the first part, this article therefore aims to define and conceptualise the term “environments for physical activity”. It refers to the term “setting” to underline the multidimensionality of environments with regard to physical activity as part of health promotion. The article indicates potential links of the concept to theories of sociology and political science by looking at the interdependency of structure (Verhältnisse) and agency (Verhalten). The second part of the article analyses a case study from physical activity promotion to demonstrate the explanatory power of the concept to intervention practice. The focus of the analysis is on an approach to structural change, i.e. the potential of changing environments for physical activity.     

Intergenerational programs for young children: Organizational procedures

Bringing together groups of preschoolers with older people is a concept that is gaining in popularity. Commonly referred to asintergenerational, these experiences — when carefully planned — have been shown to provide children with positive experiences. More specifically, the National Council on Aging defines intergenerational programs as planned activities that increase cooperation and exchange between any two generations for their mutual benefit.I never seen my great grandpa — I seen some old people in Minnesota.Brandon, age fourAlfred James is Assistant Professor of Early Childhood Education, Department of Education, Washburn University, Topeka, KS. Kathy Leon is Director of Menninger Child Care Center, Menninger, Topeka, KS.     

The relationship between linguistic characteristics and reading/writing performances of Norwegian children

The relations between different word categories and children's reading and writing performances were examined in twenty 9-year-old children. Results indicated for Norwegian, which is more regular than English but less regular than Finnish, that the length and the frequency of words and their interactions are factors substantially related both to children's reading, writing time (writing velocity), and spelling performances, whereas the regularity factor affected children's spelling only. Significant intercorrelations among reading and writing (accuracy and spelling) measures were found.     

How user innovations become commercial products: A theoretical investigation and case study

In this paper we model the pathways commonly traversed as user innovations are transformed into commercial products. First, one or more users recognize a new set of design possibilities and begin to innovate. They then join into communities, motivated by the increased efficiency of collective innovation. User-manufacturers then emerge, using high-variable/low-capital cost production methods. Finally, as user innovation slows, the market stabilizes enough for high-capital, low-variable cost manufacturing to enter. We test the model against the history of the rodeo kayak industry and find it supported. We discuss implications for “dominant design” theory and for innovation practice.     

Dwell times showcase how goal structure informs preschoolers’ analysis of unfolding motion patterns

Using Hard et al.’s (2011) dwell-time paradigm, 85 preschoolers (aged 2.5–4.5; 43 female; primarily from white families) advanced at their own pace through one of three slideshows. All slideshows depicted an actor reaching toward, grasping, and retrieving a ball. However, motion patterns differed for one slideshow (straight-reach) relative to the other two (arcing-reaches), and one of the arcing-reach slideshows depicted a violation of typical goal-related motion. Preschoolers’ knowledge of goal structure systematically modulated attention to event boundaries across slideshows despite surface differences, even when controlling for pixel change (an index of changes in motion). These findings showcase the value of the dwell time paradigm, and illuminate how children deploy attention as goal-related expectations shape their analysis of continuously unfolding activity.