3,263 research outputs found

    Population potential as a modulator of land use changes in Poland’s metropolitan areas

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    Land use is defined as a spatial distribution of individual forms of land cover patches, utilised or not utilised by humans within the framework of mutual and spatial relationships. It refers to the functional character of a given terrain, and is also identified with a socio-economic description of the land surface. Changes in land use can be interpreted as a complex and, to some extent, a random process. These assumptions serve as a point of departure in an attempt to evaluate spatial and temporal differences in land use changes in the metropolitan areas of Poland, using the entropy formula. The analysis focuses on population development as a factor that impacts upon land use change. The approach proposed here allows us to study land use dynamics in detail, with the help of cartographic visualisation

    Prediction of the hypertension risk in teenagers

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    Background: Creation of a hypertension risk stratification model and development of an algorithm to detect hypertension in teenagers. Methods: The study group consisted of 690 middle and high school students, aged 15–17 years, from the metropolitan area of Warsaw, Poland. Information concerning family history and presence of risk factors for cardiovascular disease was gathered. Three-time blood pressure measurements were taken during at least two separate visits, which were at least a week apart, using the auscultatory method, according to standard procedures. Anthropometric measurements included: body weight, height, arm, hip and abdominal circumference, skin-fold thickness measured on the rear surface of an arm, below the inferior angle of the scapula and at the belly. Following indexes were determined: body mass index (BMI), waist to hip ratio (WHR), waist to height ratio (WHtR), hip to height ratio. Results: A logistic regression model, describing the risk of hypertension in adolescents aged 15–17 was invented. π ̂(x)=e^(g ̂(x))/(1+e^(g ̂(x)) ) where: g ̂(x) = –0.097 × height + 0.085 × weight + 7.764 × WHR + 1.312 × hypertens_1(=yes). Hypertens_1 means presence of hypertension among members of the closest family.The formula was created, allowing the pre-selection of adolescents at risk of hypertension during screening. Next an algorithm for the detection of hypertension for practical use was proposed. Conclusions: Body weight, WHR and incidence of hypertension in the family are the strongest predictors of hypertension in teenagers. Proposed screening algorithm can be a useful tool for selecting teenagers at risk of hypertension and in need of specialized diagnostics and care

    Core and periphery of information society: Significance of geospatial technologies

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    The paper attempts to identify important factors significant for global information society development and to determine the significance of geospatial (geo-information) technologies. The starting point is international measures of the development level of information & communication technologies (ICT) and information society (IS). The relevance of the particular factors was defined using the general segmentation of the milieu, taking into account social, technological, economic, environmental, political, legal and ethical factors and also estimating the global spatial dimension of ICT and IS development. The diagnosis serves as the context of considerations concerning the contribution of geographers and cartographers to IS

    A Subtlety of the Schr\"{o}dinger Picture Dynamics

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    We address a mathematical and physical status of exotic (like e.g. fractal) wave packets and their quantum dynamics. To this end, we extend the formal meaning of the Schr\"{o}dinger equation beyond the domain of the Hamiltonian. The dynamical importance of the finite mean energy condition is elucidated.Comment: Minor amendments, typos corrected, to appear in Rep. Math. Phy

    Microwave absorption in YBa[2]Cu[3]O[7-delta]-manganite superlattices

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    3 pages Erreur sur l'affiliation : CEA/DSM/IRAMIS et non CEA/DSM/DRECAMInternational audienceWe report on results of direct microwave absorption measurements of Re1−x Bx MnO3 /YBa2 Cu3 O7−δ half metal/d-wave superconductor superlattices (where Re - La and Pr) and (B - Sr and Ca) for microwave frequencies in the range from 9 to 20 GHz. The measurements of the entire heterostructure were performed mostly at temperatures below the superconducting transition. The obtained results strongly depend on the microwave frequency and can be qualitatively described within the theoretical model of high-frequency properties of Josephson junctions with a ferromagnetic barrier proposed by S. Takahashi, S. Hikino, M. Mori, J. Martinek, and S. Maekawa, Phys. Rev. Lett. 99, 057003 (2007)

    A comprehensive framework for the study of species co-occurrences, nestedness and turnover

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    Binary presence–absence matrices (rows = species, columns = sites) are often used to quantify patterns of species co-occurrence, and to infer possible biotic interactions from these patterns. Previous classifications of co-occurrence patterns as nested, segregated, or modular have led to contradictory results and conclusions. These analyses usually do not incorporate the functional traits of the species or the environmental characteristics of the sites, even though the outcomes of species interactions often depend on trait expression and site quality. Here we address this shortcoming by developing a method that incorporates realized functional and environmental niches, and relates them to species co-occurrence patterns. These niches are defined from n-dimensional ellipsoids, and calculated from the n eigenvectors and eigenvalues of the variance–covariance matrix of measured environmental or trait variables. Average niche overlap among species and the spatial distribution of niches define a triangle plot with vertices of species segregation (low niche overlap), nestedness (high niche overlap), and modular co-occurrence (clusters of overlapping niches). Applying this framework to temperate understorey plant communities in southwest Poland, we found a consistent modular structure of species occurrences, a pattern not detected by conventional presence–absence analysis. These results suggest that, in our case study, habitat filtering is the most important process structuring understorey plant communities. Furthermore, they demonstrate how incorporating trait and environmental data into co-occurrence analysis improves pattern detection and provides a stronger theoretical framework for understanding community structure

    Success rate and safety of catheter ablation in preexcitation syndrome: A comparison between adult and pediatric patients

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    Background: In contrast to adults, in whom cardiac rhythm disorders are mainly conditioned by coronary artery disease, in children, arrhythmias are most often associated with inherited heart disorders. Catheter ablation (CA) has an important role in the management of cardiac arrhythmias, in adults and children. The aim of the study was to assess and compare the efficacy and safety of CA in children and adults with preexcitation syndrome. Methods: The study population comprised 43 adults and 43 children diagnosed with a Wolff-Parkinson-White syndrome (WPW). The mean age of the study population was 41 ± 15 years for adults and 14 ± 2.5 years for children. In all patients, an electrophysiological study and CA were performed. Analysis with respect to the procedure duration, fluoroscopy exposure time, location of accessory pathways (AP), immediate success rate and complications were performed. Results: Electrophysiological study revealed the most frequent presence of left-sided AP (56% in children and 70% in adults). The mean procedure duration was 96 ± 36 min and 106 ± 51 min in children and adults, respectively (p = NS). The mean fluoroscopy duration was 8.5 ± 4.3 min and 5.9 ± 5.8 min in children and adults, respectively p < 0.05. The CA procedure was successful in 40 out of 43 (93%) adults and in 36 out of 43 (83.7%) children (p = NS). In 2 (4%) children minor complications occurred. Conclusions: Ablation in children and adults are equally effective with respect to short-term clinical observation
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