Clustering is an unsupervised machine learning and pattern recognition method. In general, in addition to revealing hidden groups of similar observations and clusters, their number needs to be determined. Internal clustering validation indices estimate this number without any external information. The purpose of this article is to evaluate, empirically, characteristics of a representative set of internal clustering validation indices with many datasets. The prototype-based clustering framework includes multiple, classical and robust, statistical estimates of cluster location so that the overall setting of the paper is novel. General observations on the quality of validation indices and on the behavior of different variants of clustering algorithms will be given.

Hybrid metal nanoparticles, consisting of a nano-crystalline metal core and a protecting shell of organic ligand molecules, have applications in diverse areas such as biolabeling, catalysis, nanomedicine, and solar energy. Despite a rapidly growing database of experimentally determined atom-precise nanoparticle structures and their properties, there has been no successful, systematic way to predict the atomistic structure of the metal-ligand interface. Here, we devise and validate a general method to predict the structure of the metal-ligand interface of ligand-stabilized gold and silver nanoparticles, based on information about local chemical environments of atoms in experimental data. In addition to predicting realistic interface structures, our method is useful for investigations on the steric effects at the metal-ligand interface, as well as for predicting isomers and intermediate structures induced by thermal dynamics or interactions with the environment. Our method is applicable to other hybrid nanomaterials once a suitable set of reference structures is available.

Several studies have shown that complex nonlinear learning analytics (LA) techniques outperform the traditional ones. However, the actual integration of these techniques in automatic LA systems remains rare because they are generally presumed to be opaque. At the same time, the current reviews on LA in higher education point out that LA should be more grounded to the learning science with actual linkage to teachers and pedagogical planning. In this study, we aim to address these two challenges. First, we discuss different techniques that open up the decision-making process of complex techniques and how they can be integrated in LA tools. More precisely, we present various global and local explainable techniques with an example of an automatic LA process that provides information about different resources that can support student agency in higher education institutes. Second, we exemplify these techniques and the LA process through recently collected student agency data in four courses of the same content taught by four different teachers. Altogether, we demonstrate how this process—which we call explainable student agency analytics—can contribute to teachers’ pedagogical planning through the LA cycle.

Background: To be able to help and save lives, laypersons are recommended to undergo first aid trainings. The aim of this review was to explore the variety of the elements of the measuring systems to assess the effects of first aid trainings on different aspects of first aid skills including practical skills, knowledge, and emotional perspectives. Methods: This systematic literature review used Scopus and PubMed databases and searched for studies published between January, 2000, and December, 2020. Out of 2,162 studies meeting the search criteria, 15 studies with quantitative and repeatable evaluation methods to assess first aid skills after first aid training for adults were included in the final analysis. Results: Practical skills, especially on the ability to perform cardiopulmonary resuscitation (CPR) and to use an automated external defibrillator, were the most studied first aid skills after first aid training. This evaluation was based on several standardized measurements and assessed often with the help of a combination of resuscitation manikin and observer. Evaluation methods of performance in other emergency situations are not well standardized. Questionnaires used to assess knowledge of first aid, though seemingly based on guidelines, were also not standardized, either. Emotional aspects of first aid (willingness or self-confidence) were evaluated by highly simplified questionnaires, and answers were graded by five-point Likert scale. Conclusion: According to our review, the focus of evaluation methods after first aid training has been on practical skills and especially on CPR. Though the evaluation of first-aid knowledge seems to be straightforward, it is not performed systematically. Evaluation methods for emotional aspects are highly simplified. Overall, standardized measurements and evaluation methods to assess all aspects of first aid skills are needed.