Zoekresultaten

Rapid DNA Technologies at the Crime Scene

Which app to choose?

In recent years, there has been an exponential increase in the use of health and sports-related smartphone applications (apps). This is also reflected in App-stores, which are stacked with thousands of health- and sports-apps, with new apps launched each day. These apps have great potential to monitor and support people’s physical activity and health. For users, however, it is difficult to know which app suits their needs. In this paper, we present an online tool that supports the decision-making process for choosing an appropriate app. We constructed and validated a screening instrument to assess app content quality, together with the assessment of users’ needs. Both served as input for building the tool through various iterations with prototypes and user tests. This resulted in an online tool which relies on app content quality scores to match the users’ needs with apps that score high in the screening instrument on those particular needs. Users can add new apps to the database via the screening instrument, making the tool self-supportive and future proof. A feedback loop allows users to give feedback on the recommended app and how well it meets their needs. This feedback is added to the database and used in future filtering and recommendations. The principles used can be applied to other areas of sports, physical activity and health to help users to select an app that suits their needs. Potentially increasing the long-term use of apps to monitor and to support physical activity and health.

Identification at the crime scene

New technologies will allow Crime Scene Investigators (CSIs) in the near future to analyse traces at the crime scene and receive identification information while still conducting the investigation. These developments could have considerable effects on the way an investigation is conducted. CSIs may start reasoning based on possible database-matches which could influence scenario formation (i.e. the construction of narratives that explain the observed traces) during very early phases of the investigation. The goal of this study is to gain more insight into the influence of the rapid identification information on the reconstruction of the crime and the evaluation of traces by addressing two questions, namely 1) is scenario formation influenced from the moment that ID information is provided and 2) do database matches influence the evaluation of traces and the reconstruction of the crime. We asked 48 CSIs from England to investigate a potential murder crime scene on a computer. Our findings show that the interpretation of the crime scene by CSIs is affected by the moment identification information is provided. This information has a higher influence on scenario formation when provided after an initial scenario has been formed. Also, CSIs seem to attach great value to traces that produce matches with databases and hence yield a name of a known person. Similar traces that did not provide matches were considered less important. We question whether this kind of selective attention is desirable as it may cause ignorance of other relevant information at the crime scene.

The Physical Demands of Wheelchair Tennis Match Play: A Systematic Review with Meta‑analysis

Background Wheelchair tennis, a globally popular sport, features a professional tour spanning 40 countries and over 160 tournaments. Despite its widespread appeal, information about the physical demands of wheelchair tennis is scattered across various studies, necessitating a comprehensive systematic review to synthesise available data. Objective The aim was to provide a detailed synthesis of the physical demands associated with wheelchair tennis, encompassing diverse factors such as court surfaces, performance levels, sport classes, and sexes. Methods We conducted comprehensive searches in the PubMed, Embase, CINAHL, and SPORTDiscus databases, covering articles from inception to March 1, 2023. Forward and backward citation tracking from the included articles was carried out using Scopus, and we established eligibility criteria following the Population, Exposure, Comparison, Outcome, and Study design (PECOS) framework. Our study focused on wheelchair tennis players participating at regional, national, or international levels, including both juniors and adults, and open and quad players. We analysed singles and doubles matches and considered sex (male, female), sport class (open, quad), and court surface type (hard, clay, grass) as key comparative points. The outcomes of interest encompassed play duration, on-court movement, stroke performance, and physiological match variables. The selected study designs included observational cross-sectional, longitudinal, and intervention studies (baseline data only). We calculated pooled means or mean differences with 95% confidence intervals (CIs) and employed a random-effects meta-analysis with robust variance estimation. We assessed heterogeneity using Cochrane Q and 95% prediction intervals. Results Our literature search retrieved 643 records, with 24 articles meeting our inclusion criteria. Most available information focused on international male wheelchair tennis players in the open division, primarily competing in singles on hard courts. Key findings (mean [95% CI]) for these players on hard courts were match duration 65.9 min [55.0–78.8], set duration 35.0 min [28.2–43.5], game duration 4.6 min [0.92–23.3], rally duration 6.1 s [3.7–10.2], effective playing time 19.8% [18.9–20.7], and work-to-rest ratio 1:4.1 [1:3.7–1:4.4]. Insufficient data were available to analyse play duration for female players. However, for the available data on hard court matches, the average set duration was 34.8 min [32.5–37.2]. International male players on hard court covered an average distance per match of 3859 m [1917–7768], with mean and peak average forward speeds of 1.06 m/s [0.85–1.32] and 3.55 m/s [2.92–4.31], respectively. These players executed an average of 365.9 [317.2–422.1] strokes per match, 200.6 [134.7–299.0] per set, 25.4 [16.7–38.7] per game, and 3.4 [2.6–4.6] per rally. Insufficient data were available for a meta-analysis of female players’ on-court movement and stroke performance. The average and peak heart rates of international male players on hard court were 134.3 [124.2–145.1] and 166.0 [132.7–207.6] beats per minute, and the average match heart rate expressed as a percentage of peak heart rate was 74.7% [46.4–100]. We found no studies concerning regional players or juniors, and only one study on doubles match play. Conclusions While we present a comprehensive overview of the physical demands of wheelchair tennis, our understanding predominantly centres around international male players competing on hard courts in the open division. To attain a more comprehensive insight into the sport’s physical requirements, future research should prioritise the inclusion of data on female and quad players, juniors, doubles, and matches played on clay and grass court surfaces. Such endeavours will facilitate the development of more tailored and effective training programmes for wheelchair tennis players and coaches.

Mathematics for Databases

A formal description of a database consists of the description of the relations (tables) of the database together with the constraints that must hold on the database. Furthermore the contents of a database can be retrieved using queries. These constraints and queries for databases can very well be formalized. A formal description of a constraint or a query is necessary to describe the constraint or query unambiguously. In other words, a formal description leads to one and only one meaning of the constraint or query. To describe constraints and queries in a formal way we use predicate logic, set theory and tuple relational calculus. The tuple relational calculus is a calculus based on the use of tuple variables. A tuple variable is a variable that ranges over a named relation (i.e. a set of tuples of a relation). This paper describes the use of the relational calculus for databases. A description of the formal notation is given as well as a mapping of these expressions to SQL.

Automatic Tagging Suggestion for Database Enrichment

The huge number of images shared on the Web makes effective cataloguing methods for efficient storage and retrieval procedures specifically tailored on the end-user needs a very demanding and crucial issue. In this paper, we investigate the applicability of Automatic Image Annotation (AIA) for image tagging with a focus on the needs of database expansion for a news broadcasting company. First, we determine the feasibility of using AIA in such a context with the aim of minimizing an extensive retraining whenever a new tag needs to be incorporated in the tag set population. Then, an image annotation tool integrating a Convolutional Neural Network model (AlexNet) for feature extraction and a K-Nearest-Neighbours classifier for tag assignment to images is introduced and tested. The obtained performances are very promising addressing the proposed approach as valuable to tackle the problem of image tagging in the framework of a broadcasting company, whilst not yet optimal for integration in the business process.