High-throughput sorting of drops in microfluidic chips using electric capacitance

We analyze a recently introduced approach for the sorting of aqueous drops with biological content immersed in oil, using a microfluidic chip that combines the functionality of electrowetting with the high throughput of two-phase flow microfluidics. In this electrostatic sorter, three co-planar electrodes covered by a thin dielectric layer are placed directly below the fluidic channel. Switching the potential of the central electrode creates an electrical guide that leads the drop to the desired outlet. The generated force, which deflects the drop, can be tuned via the voltage. The working principle is based on a contrast in conductivity between the drop and the continuous phase, which ensures successful operation even for drops of highly conductive biological media like phosphate buffered saline. Moreover, since the electric field does not penetrate the drop, its content is protected from electrical currents and Joule heating. A simple capacitive model allows quantitative prediction of the electrostatic forces exerted on drops. The maximum achievable sorting rate is determined by a competition between electrostatic and hydrodynamic forces. Sorting speeds up to 1200 per second are demonstrated for conductive drops of 160 pl in low viscosity oil.     

The development of a method for identifying penalty kick strategies in association football

Penalty takers in association football adopt either a keeper-independent or a keeper-dependent strategy, with the benefits of the keeper-independent strategy presumed to be greater. Yet, despite its relevance for research and practitioners, thus far no method for identifying penalty kick strategies has been available. To develop a validated and reliable method, Experiment 1 assessed characteristics that observers should use to distinguish the two strategies. We asked participants to rate 12 characteristics of pre-recorded clips of kicks of penalty takers that used either a keeper-independent or keeper-dependent strategy. A logistic regression model identified three variables (attention to the goalkeeper, run-up fluency and kicking technique) that in combination predicted kick strategy in 92% of the penalties. We used the model in Experiment 2 to analyse prevalence and efficacy of both the strategies for penalty kicks in penalty shoot-outs during FIFA World Cups (1986–2010) and UEFA Football Championships (1984–2012). The keeper-independent strategy was used much more frequently (i.e., 78–86%) than the keeper-dependent strategy, but successes did not differ. Penalty takers should use both the strategies to be less predictable. Goalkeepers can use the developed model to improve their chances to succeed by adjusting their behaviour to penalty takers’ preferred penalty kick strategy.     

Influential structures: understanding the role of the head of department in relation to women academics’ research careers

This study was conducted at a small ‘research-led’ institution in South Africa. The data indicate that women produce less research than men and have low levels of professional self-esteem. Factors such as accrual of social capital, family responsibilities and self-esteem are constraints experienced by women academics in pursuing research careers. Mentoring was found to facilitate research career development and improve levels of self-esteem. Improved self-esteem enables women to promote themselves within their institutions and in the research arena. The role of the head of department with mentoring as a key function emerged as an influential structure for the career advancement of women academics. However, these leadership positions are significantly dominated by men and this appears to affect the amount and nature of mentoring women academics receive.     

Stress,Anxiety, and School Burnout Post COVID-19: A Study of French Adolescents

This study examined the symptoms of exhaustion, school stress and anxious school refusal from a comparative developmental perspective in French adolescents enrolled in public and private general, technological and vocational schools. It is particularly important to consider academic stress levels, anxiety and school burnout in middle and high school students as they are linked to many mental health problems, such as depression or suicidal thoughts. In this study, four hundred and ninety-three adolescents completed an online questionnaire consisting of the School Burnout Inventory, the Echelle Toulousaine de Stress Scolaire perçu and the School refusal evaluation was developed. The results show a very high percentage of suffering among teenagers. The young people most affected are high school students and more particularly students in 10th and 12th grade, with nearly three-quarters of them suffering from school burnout and/or high school stress, without any distinction between the sexes or the type of schooling.     

A Flexible Latent Class Approach to Estimating Test‐Score Reliability

The latent class reliability coefficient (LCRC) is improved by using the divisive latent class model instead of the unrestricted latent class model. This results in the divisive latent class reliability coefficient (DLCRC), which unlike LCRC avoids making subjective decisions about the best solution and thus avoids judgment error. A computational study using large numbers of items shows that DLCRC also is faster than LCRC and fast enough for practical purposes. Speed and objectivity render DLCRC superior to LCRC. A decisive feature of DLCRC is that it aims at closely approximating the multivariate distribution of item scores, which might render the method suited when test data are multidimensional. A simulation study focusing on multidimensionality shows that DLCRC in general has little bias relative to the true reliability and is relatively accurate compared to LCRC and classical lower bound methods coefficients α and λ2 and the greatest lower bound.     

Differences between students’ and teachers’ perceptions of education: profiles to describe congruence and friction

Teachers and students have their own perceptions of education. Congruent perceptions contribute to optimal teaching–learning processes and help achieving best learning outcomes. This study investigated patterns in differences between students’ and teachers’ perceptions of their learning environment. Student profiles were identified taking into account the degree of congruence/friction with teachers’ perceptions. Teacher profiles were identified based on their differences in perceptions to students. Profiles were validated with regard to learning-related student characteristics and approaches to teaching. Tenth graders (N = 994) of four secondary schools filled out the Inventory of Perceived Study Environment-Extended (IPSEE) and the Inventory of Learning Styles. Their teachers (N = 136) filled out the teacher version of the IPSEE and the Approaches to Teaching Inventory. Latent class analyses were conducted to define profiles with respect to the magnitude of differences in perceptions. Results showed three student profiles: Closest match profile (30 %), intermediate profile (59 %), and distal profile (11 %). While closest match students had desirable learning-related characteristics, others did not and are at risk for destructive friction. Two teacher profiles described idealistic teachers (70 %) and adaptive teachers (30 %), which related to approaches to teaching. Subgroups of students and teachers provide a comprehensive picture of those who are at risk because of too large differences in perceptions. This study stresses that differences in perceptions deserve detailed attention for optimising learning environments. Involving both students and teachers in the instructional design process could be a way to better account for perceptions of both stakeholders.     

Models for the development of generic skills in Finnish higher education

This article examines how Finnish universities and other higher education institutes have responded to the challenges posed by rapid changes in the world of work and societies all over Europe, particularly with reference to the development of generic skills. The data were collected by means of individual and group interviews at three Finnish higher education institutes, including two universities and one university of applied sciences. The interviews involved 63 persons in charge of management, development and teaching at these institutes. As a result of the qualitative data analysis, we distinguished four models to represent the development of generic skills, which we named (1) Specialist Model, (2) Science-based Renewal Model, (3) Project-based Integrative Model, and (4) Model of Networked Culture. These models serve as analytical tools that help higher education institutes to examine their existing practices and to develop new ones.     

Participation in online discussion environments: Is it really effective?

This study aimed to develop a rubric to assess participation of students in online discussion environments. For this purpose, the study included 168 students who participated in a course offered online during the spring semester of the 2015–2016 academic year. Developed based on the literature, the rubric consists of two parts (Form and Content, and Number and Density) and seven criteria in total. “Form and Content” consists of congruity of the message in terms of subject, clarity of the message, original value of the message, interactional value of the message, and directing the subject; whereas, “Number and Density” consists of the number of messages and their density. Four different discussion subjects were presented to the students in an online discussion environment. The researchers analyzed the students’ messages individually. Exploratory Factor Analysis was performed in order to obtain evidence for construct validity. After conducting the factor analysis, results showed that the first dimension, which is “form and content” sub-factor, is unidimensional. The “number and density” sub-factor was included in the graded scoring key based on the literature and expert opinion. The findings show that the graded scoring key is reliable and valid.     

Prerequisites for the successful group mentoring of first-year university students: a case study

In this article we present a case study on a group mentoring practice proven successful in earlier studies in terms of student self-regulation and collaboration. The purpose of our study was to uncover the factors behind the success by interviewing the mentor teachers. The findings showed that the group mentoring focused on four main themes: (a) promoting social relationships, (b) providing personal support, (c) providing study guidance, and (d) strengthening the agency of students. The findings suggest that the leading ethos of group mentoring was related to a humanistic approach to mentoring. However, successful mentoring also seemed to require both situated apprentice and critical constructivist perspectives in addition to the humanistic approach. It is concluded that the combination of multiple goals and contents in group mentoring is the main contributing factor behind the success of the mentoring model examined. Additionally, the teachers reported a variety of positive impacts of group mentoring on teachers’ work.     

数字时代期刊媒体的整合趋势

以互联网为代表的数字时代已经到来,给人类社会带来了一个突破性的进步,各行各业产业的发展,已不再受过多的时空制约.不能忽略网络的存在,不能无视网络对期刊媒体业的深刻影响.应制定面向数字时代的发展战略,找到传统期刊和网络的结合点,充分利用网络的互动优势,使期刊业焕发出新的生命力.