Towards a graph-based model of computer games

This paper proposes a new holistic approach to a formal model of computer games. The story and structure of a computer game is represented by a hierarchical layered graph, meanwhile the way that the game is played – by graph transformations. This approach enables comparative description of different games, analysis of dependencies between a game structure and players’ strategies, automatic gameplay generation, and switching from single- to multi­player mode

Continuous detection of small-scale changes in Scots pine dominated stands using dense Sentinel-2 time series

Climate change and severe extreme events, i.e., changes in precipitation and higher drought frequency, have a large impact on forests. In Poland, particularly Norway spruce and Scots pine forest stands are exposed to disturbances and have, thus experienced changes in recent years. Considering that Scots pine stands cover approximately 58% of forests in Poland, mapping these areas with an early and timely detection of forest cover changes is important, e.g., for forest management decisions. A cost-efficient way of monitoring forest changes is the use of remote sensing data from the Sentinel-2 satellites. They monitor the Earth’s surface with a high temporal (2–3 days), spatial (10–20 m), and spectral resolution, and thus, enable effective monitoring of vegetation. In this study, we used the dense time series of Sentinel-2 data from the years 2015–2019, (49 images in total), to detect changes in coniferous forest stands dominated by Scots pine. The simple approach was developed to analyze the spectral trajectories of all pixels, which were previously assigned to the probable forest change mask between 2015 and 2019. The spectral trajectories were calculated using the selected Sentinel-2 bands (visible red, red-edge 1–3, near-infrared 1, and short-wave infrared 1–2) and selected vegetation indices (Normalized Difference Moisture Index, Tasseled Cap Wetness, Moisture Stress Index, and Normalized Burn Ratio). Based on these, we calculated the breakpoints to determine when the forest change occurred. Then, a map of forest changes was created, based on the breakpoint dates. An accuracy assessment was performed for each detected date class using 861 points for 46 classes (45 dates and one class representing no changes detected). The results of our study showed that the short-wave infrared 1 band was the most useful for discriminating Scots pine forest stand changes, with the best overall accuracy of 75%. The evaluated vegetation indices underperformed single bands in detecting forest change dates. The presented approach is straightforward and might be useful in operational forest monitoring

Mean glandular dose values used for the mammography screening program in Poland according to the type of image registration system

Between 2007–2014, there have been considerable changes in the use of different types of detector systems at mammography facilities undertaking screening programs in Poland. The use of screen-film systems (termed SF systems) has largely decreased and been replaced by either computed radiography (termed CR systems) or digital radiography systems (termed DR systems); this inevitably affecting mean glandular dose values. The study aim was to evaluate changes of mean glandular dose values for a dose exposure of 4.5 cm (MGD4,5cmPMMA) achieved by using different image detectors. The study consisted of analysing 1499 protocols for quality control tests carried out by medical physicists at 16 Regional Coordination Offices in 2007, 2011, 2012 and 2013. The mean CR system values were higher than for SF systems; by 25% in 2011, by 26% in 2012, and by 28% in 2013. In subsequent years, the MGD4,5cmPMMA mean values for DR systems were higher than for SF systems by respectively 15%, 4% and 5%. Also in the subsequent years, the MGD4,5cmPMMA mean values for CR systems were higher than for DR systems by respectively 13%, 23% and 24%. In all cases, the MGD4,5cmPMMA mean values were within the acceptable level of 2.5 mGy. The MGD4,5cmPMMA mean values were different, depending on the detection system used for mammography screening in Poland

Visual Design and Reasoning with the Use of Hypergraph Transformations

This paper deals with visual design and reasoning. A visual language with its internal representation in the form of attributed hierarchical hypergraphs is discussed. Hypergraph attributes allow for defining and analysing constraints imposed by design knowledge. Operations on hypergraphs which reflect modifications of design diagrams are also presented. The approach is illustrated by examples of designing floor-layouts

Trendy zmian wartości dawek promieniowania X w mammograficznych badaniach skriningowych w Polsce vs zmiany używanych rejestratorów obrazu

Na przestrzeni lat 2007–2014 znacznie zmieniły się rodzaje rejestratora obrazu w placówkach mammograficznych realizujących program badań przesiewowych w Polsce. Odsetek systemów z detektorem filmowym (zwanych dalej systemami SF — screen-film systems) zmniejszył się w znacznym stopniu. Zostały one zastąpione przez systemy z płytami obrazowymi (zwanymi dalej systemami CR — computed radiography systems) i systemami z pełnopolowym detektorem cyfrowym (zwanymi DR — digital radiography systems), co miało wpływ na dawkę promieniowania X otrzymywaną przez kobiety podczas badań. Celem niniejszej pracy była ocena zmian, jakim podlegają wartości średnich dawek gruczołowych dla ekspozycji 4,5 cm PMMA (MGD4,5cmPMMA) w związku ze zmianą rodzaju rejestratora obrazu. Materiał pracy stanowiło 1499 protokołów z kontroli przeprowadzonych przez fizyków z 16 wojewódzkich ośrodków koordynujących w latach 2007, 2011, 2012 i 2013. Analiza wyników wykazała, że w kolejnych latach, począwszy od roku 2011, wartości średnie MGD4,5cmPMMA dla systemów CR były wyższe niż dla systemów SF: o 25%, 26% i o 28%; dla systemów DR były wyższe niż dla systemów SF: o 15%, 4% i o 5%; dla systemów CR były wyższe niż dla systemów DR o 13%, 23% i o 24%. Jednak we wszystkich przypadkach wartości średnie MGD4,5cmPMMA były na akceptowalnym poziomie 2,5 mGy. Średnie wartości MGD4,5cmPMMA znacznie różnią się w zależności od stosowanego rejestratora obrazu