Asymmetry of red blood cell motions in a microchannel with a diverging and converging bifurcation     

Leble V  Lima R  Dias R  Fernandes C  Ishikawa T  Imai Y  Yamaguchi T 《Biomicrofluidics》2011,5(4):44120-4412015

In microcirculation, red blood cells (RBCs) flowing through bifurcations may deform considerably due to combination of different phenomena that happen at the micro-scale level, such as: attraction effect, high shear, and extensional stress, all of which may influence the rheological properties and flow behavior of blood. Thus, it is important to investigate in detail the behavior of blood flow occurring at both bifurcations and confluences. In the present paper, by using a micro-PTV system, we investigated the variations of velocity profiles of two working fluids flowing through diverging and converging bifurcations, human red blood cells suspended in dextran 40 with about 14% of hematocrit level (14 Hct) and pure water seeded with fluorescent trace particles. All the measurements were performed in the center plane of rectangular microchannels using a constant flow rate of about 3.0 × 10⁻¹² m³/s. Moreover, the experimental data was compared with numerical results obtained for Newtonian incompressible fluid. The behavior of RBCs was asymmetric at the divergent and convergent side of the geometry, whereas the velocities of tracer particles suspended in pure water were symmetric and well described by numerical simulation. The formation of a red cell-depleted zone immediately downstream of the apex of the converging bifurcation was observed and its effect on velocity profiles of RBCs flow has been investigated. Conversely, a cell-depleted region was not formed around the apex of the diverging bifurcation and as a result the adhesion of RBCs to the wall surface was enhanced in this region.  相似文献   

A Review of the Brazilian Book Market     

Ricardo Costa 《Publishing Research Quarterly》2011,27(1):72-75

Brazil is a huge country with at least 100 million readers with a total population of 200 million. Is this a good number for you? The article describes the developments of the Brazilian book market and publishing industry. Sales in 2009 were an estimated $2.5 billion for more than 228 million copies of books sold. But a country this big, as it is almost 50% of entire South America, confronts several major challenges including a real lack of bookstores. But one of the channels that is growing every year are the door-to-door sales, it has grown from 5% of all sales in 2006 to 17% in 2009. In a country this big, the digital or eBooks may also be a very good strategy to get to more readers, but it is still a small market in Brazil. The interesting news is that publishers are working on it and looking for solutions and ways to act on this new area of digital and online publishing.  相似文献   

Teaching of Energy Issues: A Debate Proposal for a Global Reorientation     

Josep Lluis Doménech  Daniel Gil-Pérez  Albert Gras-Martí  Jenaro Guisasola  Joaquín Martínez-Torregrosa  Julia Salinas  Ricardo Trumper  Pablo Valdés  Amparo Vilches 《Science & Education》2007,16(1):43-64

The growing awareness of serious difficulties in the learning of energy issues has produced a great deal of research, most of which is focused on specific conceptual aspects. In our opinion, the difficulties pointed out in the literature are interrelated and connected to other aspects (conceptual as well as procedural and axiological), which are not sufficiently taken into account in previous research. This paper aims to carry out a global analysis in order to avoid the more limited approaches that deal only with individual aspects. From this global analysis we have outlined 24 propositions that are put forward for debate to lay the foundations for a profound reorientation of the teaching of energy topics in upper high school courses, in order to facilitate a better scientific understanding of these topics, avoid many students’ misconceptions and enhance awareness of the current situation of planetary emergency. This paper has been conceived as a contribution to the Decade of Education for Sustainable Development, established by the UN General Assembly for the period 2005–2014.  相似文献   

Talking About Teaching Episodes     

Ricardo?NemirovskyEmail author  Cara?DiMattia  Branca?Ribeiro  Teresa?Lara-Meloy 《Journal of Mathematics Teacher Education》2005,8(5):363-392

This paper examines two types of discourse in which teachers engage when discussing case studies based on classroom episodes, and the ways in which the availability of video data of these episodes may motivate a shift in the mode of discourse used. We interviewed two pairs of secondary school mathematics teachers after they had read a case study based on a 16-minute mathematics classroom episode taped in a secondary school in the United States. During each interview, a multimedia version of the case study, including video of the original episode, was available to the participants. We identify two modes of discourse engaged in by the teachers during the interviews: Grounded Narrative and Evaluative Discourse. We examine and identify the characteristics of the two discourse forms, drawn from both video and textual analysis. These characteristics are self-reflective talk, perspective, ethics, and linguistic patterns. The identification of two modes of discourse is relevant for researchers and teacher educators using case studies or video recordings. In addition, the findings provide insight into how teachers are “seeing” classroom events in a video case study.  相似文献   

Model-based control design for H2 purity regulation in high-pressure alkaline electrolyzers     

Martín David  Fernando Bianchi  Carlos Ocampo-Martinez  Ricardo Sánchez-Peña 《Journal of The Franklin Institute》2021,358(8):4373-4392

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Embodied-based environment for kindergarten children: Revisiting constructionist ideas     

José Armando Valente  Ricardo Caceffo  Rodrigo Bonacin  Julio Cesar dos Reis  Diego Addan Gonçalves  Maria Cecília Calani Baranauskas 《British journal of educational technology : journal of the Council for Educational Technology》2021,52(3):986-1003

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Technology-Enhanced Formative Assessment of Plant Identification     

Ricardo Conejo  Juan Ignacio Garcia-Viñas  Aitor Gastón  Beatriz Barros 《Journal of Science Education and Technology》2016,25(2):203-221

Developing plant identification skills is an important part of the curriculum of any botany course in higher education. Frequent practice with dried and fresh plants is necessary to recognize the diversity of forms, states, and details that a species can present. We have developed a web-based assessment system for mobile devices that is able to pose appropriate questions according to the location of the student. A student’s location can be obtained using the device position or by scanning a QR code attached to a dried plant sheet in a herbarium or to a fresh plant in an arboretum. The assessment questions are complemented with elaborated feedback that, according to the students’ responses, provides indications of possible mistakes and correct answers. Three experiments were designed to measure the effectiveness of the formative assessment using dried and fresh plants. Three questionnaires were used to evaluate the system performance from the students’ perspective. The results clearly indicate that formative assessment is objectively effective compared to traditional methods and that the students’ attitudes towards the system were very positive.  相似文献   

Economic globalisation,youth expectations and social class: The case of Sri Lanka     

Angela W. Little  Ricardo Sabates 《International Journal of Educational Development》2008

Whether economic globalisation is associated with a narrowing or a widening of the social class gap between the education and occupation expectations of Sri Lankan youth is examined through a test of four hypotheses. Methodologically, the study employs the estimated parameters from a system of seemingly unrelated equations for testing hypotheses. Youth expectations for education and occupation are higher than those of their parents when young. Social class effects vary among youth and fathers and mothers when young. The occupation expectations of youth show a widening gap between the middle and low social classes. In all other comparisons, the gaps are positive, indicating a widening, but none attains statistical significance. Causal explanations are explored and the implications for future investigations are identified.  相似文献   

Mindfulness for education students: addressing welfare as part of the professional training     

Ricardo Tarrasch 《Educational studies》2019,45(3):372-389

Students in special education teaching and counselling are exposed to relatively high levels of stress during their studies and their professional career, which are commonly manifested in high occupational burnout. Professional development programmes normally do not address this issue. A practicum course was developed to provide theoretical framework for research on mindfulness, training of self-application techniques, and guidelines for fieldwork teaching of these techniques to children, with the aim of improving quality of life by reducing anxiety and stress levels. Participants of mindfulness and control practicum filled questionnaires at the beginning and end of the year. Significant reduction in stress, rumination and sleep disturbances as well as elevated level of mindfulness were observed in the mindfulness practicum only. The results suggest that mindfulness training can be successfully introduced in traditional academic settings to enhance the personal mental health of future teachers, and subsequently lower their chances to suffer from burnout.  相似文献   

Childhood trauma and suicide risk in a sample of young individuals aged 14–35 years in southern Brazil     

Luana Porto Barbosa  Luciana Quevedo  Giovanna Del Grande da Silva  Karen Jansen  Ricardo Tavares Pinheiro  Jerônimo Branco  Diogo Lara  Jean Oses  Ricardo Azevedo da Silva 《Child abuse & neglect》2014

Suicide is among the main causes of death of people aged between 15 and 44 years old. Childhood trauma is an important risk factor for suicide. Hence, the objective of this study was to verify the relationship between childhood trauma and current suicide risk (suicidal behavior and ideation) in individuals aged 14–35 years, in the city of Pelotas, Brazil. This is a cross-sectional, population-based study. Sample selection was performed by clusters. Suicide risk was evaluated using the Mini International Neuropsychiatric Interview (MINI) and Childhood trauma was assessed with the Childhood Trauma Questionnaire (CTQ). Moreover, the participants responded to a questionnaire concerning socioeconomic status, work, and substance use. The sample was composed of 1,380 individuals. The prevalence of suicide risk was 11.5%. The prevalence figures of childhood trauma were 15.2% (emotional neglect), 13.5% (physical neglect), 7.6% (sexual abuse), 10.1% (physical abuse), and 13.8% (emotional abuse). Suicide risk was associated (p < .001) with gender, work, alcohol abuse, tobacco use, and all types of childhood trauma. The odds of suicide risk were higher in women (OR = 1.8), people who were not currently working (OR = 2.3), individuals who presented alcohol abuse (OR = 2.6), and among tobacco smokers (OR = 3.4). Moreover, suicide risk was increased in all types of trauma: emotional neglect (OR = 3.7), physical neglect (OR = 2.8), sexual abuse (OR = 3.4), physical abuse (OR = 3.1), and emotional abuse (OR = 6.6). Thus, preventing early trauma may reduce suicide risk in young individuals.  相似文献