The twin prime problem and generalizations (après Yitang Zhang)

We give a short introduction to the recent breakthrough theorem of Yitang Zhang that there are infinitely many pairs of distinct primes (p, q) with |p ? q| < 70 million.     

Towards a Competency Model for Teaching Computer Science

To address the special challenges of teaching computer science, adequate development of teachers’ competencies during their education is extremely important. In particular, pedagogical content knowledge and teachers’ beliefs and motivational orientations play an important role in effective teaching. This research field has been sparsely investigated up to now and there exists no consistent competency model for teaching computer science in Germany. Therefore, this paper describes the development of competency in the areas of pedagogical content knowledge, teachers’ beliefs, and motivational orientations with regard to computer science. Competency-relevant factors for teaching computer science are theoretically derived and concretely formulated with the help of expert interviews conducted according to the critical incident technique and analyzed using techniques of qualitative content analysis.     

Sincretismo y pensamiento categorial: génesis y diferencias socioculturales

Resumen

El estudio de la representación del mundo en el niño es una de las vías que permiten acercarse a la génesis del pensamiento infantil, a su progresiva estructuración. Interesados en la evolución del sincretismo y del pensamiento categorial, los diálogos con los niños en torno a las ultra-cosas nos han permitido detectar distintos niveles evolutivos dentro del pensamiento sincrétn o y del categorial y nos han puesto en la pista de posibles diferencias socioculturales ligadas con la pertenencia al medio rural o urbano.     

Changes in Sensory Dominance During Childhood: Converging Evidence From the Colavita Effect and the Sound‐Induced Flash Illusion

In human adults, visual dominance emerges in several multisensory tasks. In children, auditory dominance has been reported up to 4 years of age. To establish when sensory dominance changes during development, 41 children (6–7, 9–10, and 11–12 years) were tested on the Colavita task (Experiment 1) and 32 children (6–7, 9–10, and 11–12 years) were tested on the sound‐induced flash illusion (Experiment 2). In both experiments, an auditory dominance emerged in 6‐ to 7‐year‐old children compared to older children. Adult‐like visual dominance started to emerge from 9 to 10 years of age, and consolidated in 11‐ to 12‐year‐old children. These findings show that auditory dominance persists up to 6 years, but switches to visual dominance during the first school years.     

Spelling well despite developmental language disorder: what makes it possible?

The goal of the study was to investigate the overlap between developmental language disorder (DLD) and developmental dyslexia, identified through spelling difficulties (SD), in Russian-speaking children. In particular, we studied the role of phoneme awareness (PA), rapid automatized naming (RAN), pseudoword repetition (PWR), morphological (MA), and orthographic awareness (OA) in differentiating between children with DLD who have SD from children with DLD who are average spellers by comparing the two groups to each other, to typically developing children as well as children with SD but without spoken language deficits. One hundred forty-nine children, aged 10.40 to 14.00 years, participated in the study. The results indicated that the SD, DLD, and DLD/SD groups did not differ from each other on PA and RAN Letters and underperformed in comparison to the control groups. However, whereas the children with written language deficits (SD and DLD/SD groups) underperformed on RAN Objects and Digits, PWR, OA, and MA, the children with DLD and no SD performed similarly to the children from the control groups on these measures. In contrast, the two groups with spoken language deficits (DLD and DLD/SD) underperformed on RAN Colors in comparison to the control groups and the group of children with SD only. The results support the notion that those children with DLD who have unimpaired PWR and RAN skills are able to overcome their weaknesses in spoken language and PA and acquire basic literacy on a par with their age peers with typical language. We also argue that our findings support a multifactorial model of DLD.     

Professional guilds, tension and knowledge management

Scientific research is a crucial success factor for knowledge intensive firms and is often a joint effort of scientists and managers. However, scientists and managers belong to different “professional guilds,” subscribing to different belief systems and valuing different types of incentives. These differences give rise to tension between scientists and managers. We integrate a large body of literature from knowledge management to develop a new theoretical model predicting that this organizational tension is affected by environmental factors such as the degree of industry munificence, firm-specific factors like knowledge-management policies, and the individual roles of boundary spanners within the firm. Further, we argue that this tension can lead to positive or negative outcomes.     

UpToDate versus DynaMed: a cross-sectional study comparing the speed and accuracy of two point-of-care information tools

Objective:To compare the accuracy, time to answer, user confidence, and user satisfaction between UpToDate and DynaMed (formerly DynaMed Plus), which are two popular point-of-care information tools.Methods:A crossover study was conducted with medical residents in obstetrics and gynecology and family medicine at the University of Toronto in order to compare the speed and accuracy with which they retrieved answers to clinical questions using UpToDate and DynaMed. Experiments took place between February 2017 and December 2019. Following a short tutorial on how to use each tool and completion of a background survey, participants attempted to find answers to two clinical questions in each tool. Time to answer each question, the chosen answer, confidence score, and satisfaction score were recorded for each clinical question.Results:A total of 57 residents took part in the experiment, including 32 from family medicine and 25 from obstetrics and gynecology. Accuracy in clinical answers was equal between UpToDate (average 1.35 out of 2) and DynaMed (average 1.36 out of 2). However, time to answer was 2.5 minutes faster in UpToDate compared to DynaMed. Participants were also more confident and satisfied with their answers in UpToDate compared to DynaMed.Conclusions:Despite a preference for UpToDate and a higher confidence in responses, the accuracy of clinical answers in UpToDate was equal to those in DynaMed. Previous exposure to UpToDate likely played a major role in participants'' preferences. More research in this area is recommended.     

Proofs produced by secondary school students learning geometry in a dynamic computer environment

As a key objective, secondary school mathematics teachers seek to improve the proof skills of students. In this paper we present an analytic framework to describe and analyze students' answers to proof problems. We employ this framework to investigate ways in which dynamic geometry software can be used to improve students' understanding of the nature of mathematical proof and to improve their proof skills. We present the results of two case studies where secondary school students worked with Cabri-Géeomèetre to solve geometry problems structured in a teaching unit. The teaching unit had theaims of: i) Teaching geometric concepts and properties, and ii) helping students to improve their conception of the nature of mathematical proof and to improve their proof skills. By applying the framework defined here, we analyze students' answers to proof problems, observe the types of justifications produced, and verify the usefulness of learning in dynamicgeometry computer environments to improve students' proof skills.