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11.
In this study, we show the importance of extensional rheology, in addition to the shear rheology, in the choice of blood analog solutions intended to be used in vitro for mimicking the microcirculatory system. For this purpose, we compare the flow of a Newtonian fluid and two well-established viscoelastic blood analog polymer solutions through microfluidic channels containing both hyperbolic and abrupt contractions∕expansions. The hyperbolic shape was selected in order to impose a nearly constant strain rate at the centerline of the microchannels and achieve a quasihomogeneous and strong extensional flow often found in features of the human microcirculatory system such as stenoses. The two blood analog fluids used are aqueous solutions of a polyacrylamide (125 ppm w∕w) and of a xanthan gum (500 ppm w∕w), which were characterized rheologically in steady-shear flow using a rotational rheometer and in extension using a capillary breakup extensional rheometer (CaBER). Both blood analogs exhibit a shear-thinning behavior similar to that of whole human blood, but their relaxation times, obtained from CaBER experiments, are substantially different (by one order of magnitude). Visualizations of the flow patterns using streak photography, measurements of the velocity field using microparticle image velocimetry, and pressure-drop measurements were carried out experimentally for a wide range of flow rates. The experimental results were also compared with the numerical simulations of the flow of a Newtonian fluid and a generalized Newtonian fluid with shear-thinning behavior. Our results show that the flow patterns of the two blood analog solutions are considerably different, despite their similar shear rheology. Furthermore, we demonstrate that the elastic properties of the fluid have a major impact on the flow characteristics, with the polyacrylamide solution exhibiting a much stronger elastic character. As such, these properties must be taken into account in the choice or development of analog fluids that are adequate to replicate blood behavior at the microscale. 相似文献
12.
Carolina V. M. Azevedo Ivanise Sousa Ketema Paul Marlene Y. MacLeish M Teresa Mondéjar Juan Antonio Sarabia M. Ángeles Rol Juan Antonio Madrid 《Mind, Brain, and Education》2008,2(1):34-47
ABSTRACT— Early morning school schedules are in the opposite direction to the sleep–wake cycle in adolescence and early adulthood. This conflict leads to sleep deprivation and irregular patterns whose consequences are scarcely explored. This article discusses the effects of three educational experiences with high school students, parents, teachers, and medical students. The first experience was developed with high school students in Natal, Brazil, to determine whether sleep habits would improve with increased awareness. Positive effects were observed in some aspects of sleep knowledge and practices. In the second experience in Atlanta, GA, sleep education activities were presented to middle and high school teachers, parents, and students to emphasize the importance of sleep. In the third program in Murcia, Spain, undergraduate medical students were introduced to chronobiology of sleep by a practical exercise that pointed out to what extent they shared most of adolescent sleep characteristics. Educational chronobiological experiences about sleep are essential to develop healthy sleep habits in the general population, particularly in students. 相似文献
13.
Erin Bentrim, Kim Sousa‐Peoples, Garrett Kachellek, and Wendy Powers report the results of assessing the effect of students' work experiences on their personal and academic development. 相似文献
14.
Firms are encouraged to continually initiate innovation activities as part of their new product development processes and to be open to the use of external knowledge sources. Yet, many are abandoned. Openness to external knowledge sources and the experience of abandoning innovation activities are, therefore, becoming a part of an organization’s reality and innovation strategy. In this paper, we aim to explore how the experience of having abandoned an innovation activity can affect innovation performance and the role two key dimensions of openness, external search breadth and formal innovation collaboration breadth, play. Using data from the UK Innovation Survey, we find that the experience of having abandoned an innovation activity leads to improved innovation performance and that this is negatively moderated by the two dimensions of openness. When external search breadth is high, i.e. when an organization engages with a higher number of different types of knowledge sources, the link between abandoning innovation activities and innovation performance weakens. Similarly, when formal innovation collaboration breadth is high, i.e. the breadth of a firm’s formal collaboration relationships is high, the link between abandoning innovation activities and innovation performance also weakens. We conclude by discussing the theoretical and practical implications of our findings. 相似文献
15.
de Oliveira Silva Jorge Henrique de Sousa Mendes Glauco Henrique Ganga Gilberto Miller Devós Mergulhão Ricardo Coser Lizarelli Fabiana Letícia 《International Journal for Educational and Vocational Guidance》2020,20(2):351-373
International Journal for Educational and Vocational Guidance - This article proposes a model of antecedents and consequences of student satisfaction in Higher Technical-Vocational Education (HTVE)... 相似文献
16.
Anabela C. Alves Rui M. Sousa Sandra Fernandes Elisabete Cardoso Maria Alice Carvalho Jorge Figueiredo 《European Journal of Engineering Education》2016,41(2):123-141
Project-Based Learning (PBL) has been implemented in the first year of the Industrial Engineering and Management programme at the University of Minho, Portugal, since 2004/2005. The purpose of this paper is to analyse and discuss teachers' experiences in PBL in this programme and to explore its implications for student learning and for teaching practices in higher education. For data collection, the research method used was written narratives to these teachers, at the end of the PBL semester. Findings suggest that teachers express a positive view of PBL as a learning approach. They identify student motivation and engagement, along with a better understanding of the application of concepts in real-life situations, as important outcomes of the project for students. Besides this, teachers also highlight the importance of the development of transversal skills by students throughout the project. Recommendations for future work and implications for practice will also be discussed. 相似文献
17.
da Silva Alexandre Sousa Barbosa Maria Tereza Serrano de Souza Velasque Luciane da Silveira Barroso Alves Davi Magalhães Marcos Nascimento 《Educational Studies in Mathematics》2021,108(1-2):269-289
Educational Studies in Mathematics - The world is now facing the most severe health, social, and economic event of the last hundred years, which has made the need to acquire statistical thinking to... 相似文献
18.
Silvania Sousa do Nascimento 《Cultural Studies of Science Education》2013,8(2):497-503
The original article by Kamberelis and Wehunt (2012) discusses an interesting and important research subject in science education as it focus on classroom interactions and the characteristics of the discourse production of interlocutors. The authors start from the premise that discourse heterogeneity is constitutive of social activities, which is supported by others like Mikhail Bakhtin (Speech genres and other late essays. University of Texas Press, Austin, 1981) and Erving Goffman (Frame analysis: an essay on the organization of experience. Harper and Row, London, 1974). They also present the definitions of three key elements that organize hybrid discourse: (a) lamination of multiple cultural frames, (b) shifting relations between people and their discourse, and (c) shifting power relations between people. Finally, the authors analyze how these three elements organize students’ science discourse in the classroom and how it contributes to the creation of a micro-community of practice capable of helping the emergence of a disciplinary knowledge that is legitimized by and strengthens the identity of the group. In the present commentary, I discuss how Michael Foucault’s (1970) concept of discursive procedure may help us to analyze the (often neglected) teacher’s role in the development of hybrid discourse practices. 相似文献
19.
Daniela Figueiredo Ana Barbosa Joana Cruz Alda Marques Liliana Sousa 《Educational gerontology》2013,39(6):413-427
This pilot-study aimed to assess a psychoeducational program for staff in care homes. The program was designed to increase knowledge regarding dementia care, promote skills to integrate motor and multisensory stimulation in daily care, and develop coping strategies to manage emotional work-related demands. Six staff members received eight psychoeducational sessions held fortnightly and individualized assistance during the provision of morning care to six residents with dementia. An audio-recorded focus group interview with staff and video recordings of residents' behavior during morning care were made and used to assess the program. Staff reported several benefits: acquisition of new knowledge; demystification of preexisting beliefs related to dementia; group cohesion; self-worth feelings; and positive coping. A trend towards improvements at residents' levels of interaction was found. The findings suggest the need of interventions to go beyond the objectives exclusively centered on staff education and the promotion of residents' well-being. This should be achieved by also allowing workers to feel supported and empowered. 相似文献
20.
Srinivas Velugotla Steve Pells Heidi K. Mjoseng Cairnan R. E. Duffy Stewart Smith Paul De Sousa Ronald Pethig 《Biomicrofluidics》2012,6(4)
Assessment of the dielectrophoresis (DEP) cross-over frequency (fxo), cell diameter, and derivative membrane capacitance (Cm) values for a group of undifferentiated human embryonic stem cell (hESC) lines (H1, H9, RCM1, RH1), and for a transgenic subclone of H1 (T8) revealed that hESC lines could not be discriminated on their mean fxo and Cm values, the latter of which ranged from 14 to 20 mF/m2. Differentiation of H1 and H9 to a mesenchymal stem cell-like phenotype resulted in similar significant increases in mean Cm values to 41–49 mF/m2 in both lines (p < 0.0001). BMP4-induced differentiation of RCM1 to a trophoblast cell-like phenotype also resulted in a distinct and significant increase in mean Cm value to 28 mF/m2 (p < 0.0001). The progressive transition to a higher membrane capacitance was also evident after each passage of cell culture as H9 cells transitioned to a mesenchymal stem cell-like state induced by growth on a substrate of hyaluronan. These findings confirm the existence of distinctive parameters between undifferentiated and differentiating cells on which future application of dielectrophoresis in the context of hESC manufacturing can be based. 相似文献