Geometrical effects in microfluidic-based microarrays for rapid, efficient single-cell capture of mammalian stem cells and plant cells     

Lawrenz A  Nason F  Cooper-White JJ 《Biomicrofluidics》2012,6(2):24112-2411217

In this paper, a detailed numerical and experimental investigation into the optimisation of hydrodynamic micro-trapping arrays for high-throughput capture of single polystyrene (PS) microparticles and three different types of live cells at trapping times of 30 min or less is described. Four different trap geometries (triangular, square, conical, and elliptical) were investigated within three different device generations, in which device architecture, channel geometry, inter-trap spacing, trap size, and trap density were varied. Numerical simulation confirmed that (1) the calculated device dimensions permitted partitioned flow between the main channel and the trap channel, and further, preferential flow through the trap channel in the absence of any obstruction; (2) different trap shapes, all having the same dimensional parameters in terms of depth, trapping channel lengths and widths, main channel lengths and widths, produce contrasting streamline plots and that the interaction of the fluid with the different geometries can produce areas of stagnated flow or distorted field lines; and (3) that once trapped, any motion of the trapped particle or cell or a shift in its configuration within the trap can result in significant increases in pressures on the cell surface and variations in the shear stress distribution across the cell’s surface. Numerical outcomes were then validated experimentally in terms of the impact of these variations in device design elements on the percent occupancy of the trapping array (with one or more particles or cells) within these targeted short timeframes. Limitations on obtaining high trap occupancies in the devices were shown to be primarily a result of particle aggregation, channel clogging and the trap aperture size. These limitations could be overcome somewhat by optimisation of these device design elements and other operational variables, such as the average carrier fluid velocity. For example, for the 20 μm polystyrene microparticles, the number of filled traps increased from 32% to 42% during 5–10 min experiments in devices with smaller apertures. Similarly, a 40%–60% reduction in trapping channel size resulted in an increase in the amount of filled traps, from 0% to almost 90% in 10 min, for the human bone marrow derived mesenchymal stem cells, and 15%–85% in 15 min for the human embryonic stem cells. Last, a reduction of the average carrier fluid velocity by 50% resulted in an increase from 80% to 92% occupancy of single algae cells in traps. Interestingly, changes in the physical properties of the species being trapped also had a substantial impact, as regardless of the trap shape, higher percent occupancies were observed with cells compared to single PS microparticles in the same device, even though they are of approximately the same size. This investigation showed that in microfluidic single cell capture arrays, the trap shape that maximizes cell viability is not necessarily the most efficient for high-speed single cell capture. However, high-speed trapping configurations for delicate mammalian cells are possible but must be optimised for each cell type and designed principally in accordance with the trap size to cell size ratio.  相似文献   

Newborns' face recognition: role of inner and outer facial features   总被引：1，自引：0，他引：1  

Turati C  Macchi Cassia V  Simion F  Leo I 《Child development》2006,77(2):297-311

Existing data indicate that newborns are able to recognize individual faces, but little is known about what perceptual cues drive this ability. The current study showed that either the inner or outer features of the face can act as sufficient cues for newborns' face recognition (Experiment 1), but the outer part of the face enjoys an advantage over the inner part (Experiment 2). Inversion of the face stimuli disrupted recognition when only the inner portion of the face was shown, but not when the whole face was fully visible or only the outer features were presented (Experiment 3). The results enhance our picture of what information newborns actually process and encode when they discriminate, learn, and recognize faces.  相似文献   

Lessons learned from single service point implementations     

Allegri F  Bedard M 《Medical reference services quarterly》2006,25(2):31-47

Interest in consolidating service points within health sciences libraries continues. This article proposes a definition of a library single service point and mentions some notable examples in academic health sciences libraries. The experiences of two of these libraries are summarized and compared, and the advice culled from those experiences is shared. The advice is in the form of sharing lessons learned, answering six frequently asked questions about combining services and staff under a single service umbrella. The article offers insights for other library staff considering this type of service reorganization.  相似文献   

Conservation of stained glass windows with protective glazing: Main results from the European VIDRIO research programme     

Adriana Bernardi  Francesca Becherini  Marco Verità  Patrick Ausset  Maura Bellio  Ulrike Brinkmann  Helene Cachier  Anne Chabas  Felix Deutsch  Marie-Pierre Etcheverry  Franco Geotti Bianchini  Ricardo H.M. Godoi  Velichka Kontozova-Deutsch  Roger Lefèvre  Tiziana Lombardo  Peter Mottner  Chiara Nicola  Isabelle Pallot-Frossard  René Van Grieken 《Journal of Cultural Heritage》2013,14(6):527-536

The methodology of protecting the European stained glass windows against environmental risk (e.g. meteorological factors, air pollution, microorganisms) by means of an external glazing is not new. In spite of many scientific studies carried out in the last 20 years, some questions were still up for discussion. The European VIDRIO (2002–2005) project gave an answer to these questions. The research carried out by the different project partners established a new multidisciplinary approach aimed at evaluating the efficiency of the protective glazing systems and their effects on stained glass windows conservation, and finally at assessing the most appropriate strategy to preserve stained glass windows. Scientific results showed that the so-called isothermal glazing (i.e. ventilation by the air coming from the inside of the building) protected efficiently the ancient stained glass window from environmental attack (i.e. rain, pollutants, condensation, thermal shocks) with very limited secondary effects. The scientific research highlighted that its efficiency was strongly related to the technical design of the protective system. In particular, the ventilation and the size of the interspace had to be carefully considered. The research developed within the VIDRIO project was turned into general recommendations to the owners and practitioners on the best practice for the stained glass windows future conservation.  相似文献   

Sex,Love, and Risk-n-Responsibility: A Content Analysis of Entertainment Television     

Francesca R. Dillman Carpentier  Elise M. Stevens  Lu Wu  Natalee Seely 《Mass Communication and Society》2017,20(5):686-709

This study documents the extent of sexual content, including sexual health content, in scenes with and without expressions of love on network and cable television popular with emerging adults. Sexual talk and/or behavior was found in 20% of all television scenes coded across 53.5 hours of programming. One third of these scenes featured sex alongside expressions of love. An additional 10% of scenes suggested love but not sex. Coded as a separate category, 25% of analyzed scenes contained a passing joke or pun referencing sexual organs, making these nonspecific, comedic one-liners the predominant reference to sex in this sample. Beyond jokes, most of the sexual or loving talk in this sample consisted of expressing a romantic interest in someone; sex- and love-related behaviors largely consisted of kissing or flirting. Very few scenes specifically referenced sexual intercourse. Sexual health messages were also rare. The majority of scenes mentioning any health consequence (7% of analyzed scenes) concerned emotional heartache. One scene mentioned sexually transmitted infections; 12 of the nearly 2,600 scenes coded mentioned condoms or contraceptives. It is thus a challenging proposition to build upon existing sexual depictions on television to promote safe sex practices within sexual and loving contexts.  相似文献   

Researching Researchers: Meeting Changing Researcher Needs in a Special Collections Environment     

Francesca Baseby 《New Review of Academic Librarianship》2017,23(2-3):185-194

ABSTRACT

In the competitive Higher Education environment, it is no longer sufficient for special collections to rely on the “uniqueness” of a collection as its unique selling point—it must be supported by a service and strategic plan that is both proactive in anticipating the demands of future researchers and responsive to current researchers’ changing needs. Edinburgh University's Centre for Research Collections (CRC) is addressing this challenge for the first time in a coordinated manner, employing a suite of research methods that allow staff to take an evidence based approach to service development and strategic planning. These include ethnographic observation, structured surveys, object-based learning initiatives, comprehensive data interrogation, and active engagement with the University's academic schools. This article examines how these approaches have been utilized in the development of CRC services, and its benefit to long-term planning.  相似文献   

Beware of Stereotypes: Are Classmates’ Stereotypes Associated With Students’ Reading Outcomes?     

Francesca Muntoni  Jenny Wagner  Jan Retelsdorf 《Child development》2021,92(1):189-204

This study examined the associations between classmates’ reading-related gender stereotypes and students’ reading self-efficacy, self-concept, motivation, and achievement. Our sample consisted of 1,508 fifth-grade students (49% girls; age: 10.89 years); data were collected at two time points. Multilevel analyses yielded two main results: First, there was a relation between students’ individual reading-related gender stereotypes and their reading self-concept, self-efficacy, and motivation with boys experiencing negative and girls experiencing positive effects. Second, a contextual effect was found: after controlling for students’ individual reading-related gender stereotypes, classmates’ gender stereotypes were negatively related to all of the boys’ reading outcomes. The results provide evidence for the assumption that classmates are important communicators of gender stereotypes and that they reinforce conforming behaviors.  相似文献   

Children in residential care: How to evaluate behavioural change     

Paola Bastianoni  Ettore Scappini  Francesca Emiliani 《European Journal of Psychology of Education - EJPE》1996,11(4):459-471

This article reports the results of an observational longitudinal study carried out on four children who lived in a residential community because of their multiproblem families. The aim of this study was to apply the evaluative methodology proposed by Le Poultier (1990) in order to assess I) the processes of change in the children over time and II) the relations between educational practices and observed changes. The findings confirm I) the existence of processes of change in the children; II) the presence of correlations between the displayed behaviour of the children and adult practices. In addition, what emerges is the existence of a dimension (transgression versus co-operation and autonomy) underlying the educational project designed by the adults. The data refer to observations of the behaviour of each staff member on a weekly basis for a six-month period and, at the same time, to the self-observations of each adult regarding the behaviour adopted towards each child. The data were analysed using: I) correlational coefficients to check the relation between the children's behaviour and the social work; II) Correspondence Analysis to permit a simultaneous representation of the developmental changes observed in the four children with respect to social work.  相似文献   

Origins of individual differences in theory of mind: from nature to nurture?     

Hughes C  Jaffee SR  Happé F  Taylor A  Caspi A  Moffitt TE 《Child development》2005,76(2):356-370

In this study of the origins of individual differences in theory of mind (ToM), the Environmental Risk (E-Risk) Longitudinal Twin Study sample of 1,116 sixty-month-old twin pairs completed a comprehensive battery of ToM tasks. Individual differences in ToM were striking and strongly associated with verbal ability. Behavioral genetic models of the data showed that environmental factors explained the majority of the variance in ToM performance in this sample. Shared environmental influences on verbal ability had a common impact on ToM and explained more than half the phenotypic correlation between these two skills. Possible underlying proximal mechanisms are discussed, including maternal speech and mind-mindedness, sibling interactions, and peer influences.  相似文献   

Individual differences in spatial text processing: High spatial ability can compensate for spatial working memory interference     

Chiara Meneghetti  Valrie Gyselinck  Francesca Pazzaglia  Rossana De Beni 《Learning and individual differences》2009,19(4):577-589

The present study investigates the relation between spatial ability and visuo-spatial and verbal working memory in spatial text processing. In two experiments, participants listened to a spatial text (Experiments 1 and 2) and a non-spatial text (Experiment 1), at the same time performing a spatial or a verbal concurrent task, or no secondary task. To understand how individuals who differ in spatial ability process spatial text during dual task performance, spatial individual differences were analyzed. The tasks administered were the Vandenberg and Kuse [Vandenberg, S. G., & Kuse, A. R. (1978). Mental rotation, a group test of three-dimensional spatial visualization. Perceptual and Motor Skills, 47, 599-604.] mental rotation test (MRT) and a reading comprehension task (RCT). Individuals with high (HMR) and low (LMR) mental rotation differed in MRT scores but had similar RCT performance. Results showed that the HMR group, in contrast with LMR counterparts, preserved good spatial text recall even when a spatial concurrent task was performed; however, Experiment 2 revealed a modification of spatial concurrent task performance in LMR as well in HMR group. Overall, results suggest that HMR individuals have more spatial resources than LMR individuals, allowing them to compensate for spatial working memory interference, but only to a limited extent, given that the processing of spatial information is still mediated by VSWM.  相似文献