Simulation and experimental determination of the online separation of blood components with the help of microfluidic cascading spirals

Microfluidic spirals were used to successfully separate rare solid components from unpretreated human whole blood samples. The measured separation ratio of the spirals is the factor by which the concentration of the rare component is increased due to the Dean effect present in a flow profile in a curved duct. Different rates of dilution of the blood samples with a phosphate-buffered solution were investigated. The diameters of the spherical particles to separate ranged from 2 μm to 18 μm. It was found that diluting the blood to 20% is optimal leading to a separation ratio up to 1.97. Using two spirals continuously placed in a row led to an increase in separation efficacy in samples consisting of phosphate-buffered solution only from 1.86 to 3.79. Numerical investigations were carried out to display the flow profiles of Newtonian water samples and the shear-thinning blood samples in the cross-section of the experimentally handled channels. A macroscopic difference in velocity between the two rheologically different fluids could not be found. The macroscopic Dean flow is equally present and useful to help particles migrate to certain equilibrium positions in blood as well as lower viscous Newtonian fluids. The investigations highlight the potential for using highly concentrated, very heterogeneous, and non-Newtonian fluidic systems in known microsystems for screening applications.     

Anorexia athletica in pre-professional ballet dancers

Competitive sport has been under increasing discussion as a possible favourable factor in the development of eating disorders among children and adolescents. The aim of this study was to determine the frequency of sport-specific eating disorders, in line with the concept of anorexia athletica. This prospective field study included one experimental group and two control groups (disease and healthy). Fifty-two pre-professional ballet dancers aged 13-20 years were tested for clinical eating disorders, anorexia athletica criteria, eating disorder related psychopathology and self-concept, and were compared with 52 patients with anorexia nervosa and 44 non-athletic controls of the same age. The study was conducted using semi-structured interviews as well as self-report questionnaires. A clinical eating disorder diagnosis was made in 1.9% of the ballet dancers versus 0% of the high school students; anorexia athletica was diagnosed in 5.8% of the dancers versus 2.3% of the students. Ballet dancers scored lower than patients with anorexia nervosa with regard to eating disorder related psychopathology and higher than the patients with regard to self-concept. We conclude that more sensitive tools to differentiate between sport-specific (eating) patterns, anorexia athletica and clinically relevant eating disorders are needed, especially for aesthetic sports such as ballet. It remains an important goal to identify athletes with symptoms of anorexia athletica irrespective of their physique and/or sport.     

Teaching at a Distance — Reflections on the relationship between discipline‐based and general teaching theories

German readers would immediately associate the term ‘discipline-based’ with Didaktik, which in the German-speaking world is an established branch of education science. The first section therefore deals with the development of Didaktik, understood as a theory of teaching and learning which seeks to investigate the relationships between discipline-based and general teaching theories. Didaktik was originally a strictly theory-oriented discipline in German-speaking countries, but changes in its terms of reference have led to an acceptance of the more pragmatically oriented curriculum theory of the English-speaking world. The term ‘discipline-based’ seems to indicate that here, too, education science has turned its back on positivistic, ‘purely scientific’ standards, so a knowledge of the German discussion of teaching-learning theory may be of interest.

The second section shows that in distance education, too, general teaching models need concretization in terms of discipline-based teaching theory, and that on the other hand, any discipline-based theory needs to have its foundations in general teaching theory, i.e. in pedagogic principles.

The third section therefore postulates the necessity of a theory of distance education which is based on practical experience.     

Performance of students in project‐based science classrooms on a national measure of science achievement

Reform efforts in science education emphasize the importance of supporting students' construction of knowledge through inquiry. Project‐based science (PBS) is an ambitious approach to science instruction that addresses concerns of reformers. A sample of 142 10th‐ and 11th‐grade students enrolled in a PBS program completed the 12th‐grade 1996 National Assessment of Educational Progress (NAEP) science test. Compared with subgroups identified by NAEP that most closely matched our student sample, White and middle class, PBS students outscored the national sample on 44% of NAEP test items. This study shows that students participating in a PBS curriculum were prepared for this type of testing. Educators should be encouraged to use inquiry‐based approaches such as PBS to implement reform in their schools. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 410–422, 2002     

Questionnaires as interventions: can taking a survey increase teachers’ openness to student feedback surveys?

Administrators often struggle in getting teachers to trust their school’s evaluation practices – a necessity if teachers are to learn from the feedback they receive. We attempted to bolster teachers’ support for receiving evaluative feedback from a particularly controversial source: student-perception surveys. For our intervention, we took one of two approaches to asking 309 teachers how they felt about students evaluating their teaching practice. Control participants responded only to core questions regarding their attitudes towards student-perception surveys. Meanwhile, treatment participants were first asked whether teachers should evaluate administrators in performance reviews and were then asked the core items about student-perception surveys. Congruent with cognitive dissonance theory, this juxtaposition of questions bolstered treatment teachers’ support for using student surveys in teacher evaluations relative to the control group. We discuss the implications of these findings with respect to increasing teacher openness to alternative evaluation approaches, and consider whether surveys show promise as a vehicle for delivering interventions.     

Educational Interventions to Improve Dental Anatomy Carving Ability of Dental Students: A Systematic Review

This systematic review aimed to identify the level of impact of educational strategies for teaching tooth carving on the carving ability of undergraduate dental students. The PubMed-NCBI, Cochrane-CENTRAL, LILACS, Ibecs, BBO, Web of Science, and Scopus databases were searched in May 2019, for randomized controlled trials (RCTs) and two-arm non-randomized studies of interventions (NRSI) addressing educational interventions toward the dental carving of undergraduate students. Studies from the year 2000 until the search date, written in English, Portuguese, and Spanish were included. Study screening and data extraction were performed in duplicate and blinded. The data were presented narratively, considering the dental carving ability of students the primary outcome. The risk of bias was assessed using the RoB tool 2.0 and ROBINS-I, and the level of evidence was determined with GRADE. Of 3,574 studies, 6 were included, with 3 RCTs and 3 NRSIs. Very low level of evidence was provided from the NRSIs that flipped classroom (1 study; n = 140) and a student-driven revised module (1 study; n = 264) improved the carving ability of students. Additionally, there was moderate evidence of online complementary material (1 RCT; n = 30) and reinforcement class improving the carving ability of students (1 RCT; n = 29). The replacement of traditional classes by an instructional DVD (1 RCT; n = 73) and assessment of carving projects through digital systems (1 NRSI; n = 79) did not enhance the carving ability of students. Study design, risk of bias, and imprecision downgraded the level of evidence. There was a very low to moderate evidence on the effectiveness of student-driven educational approaches and complementary classes of dental anatomy in improving the dental carving ability of students.