The rise of private higher education in Poland: policies, markets and strategies

The rationale for this study lies in our wish to understand the rapid rise of private higher education in Poland and the effects this has had on the dynamics of the Polish higher education system as a whole. After 1989, the year when Poland was freed of its communist ties, Polish higher education, like other sectors in the economy, went through a rapid period of reform that may be characterized by the words liberalisation, marketisation or privatisation

Mineralogy and deformation structures in components of clastic sediments from the Morasko meteorite lake

The paper presents mineralogical analysis of sediments of the biggest lake formed on the Morasko Meteorite Reserve (Poland) in terms of presence of matter of their origin. The lake are filled by phytogenic sediments at the top, while at their bottom occur Neogene clays. The main components are: clay minerals in fine fraction and quartz and feldspars in coarse sandy fractions. The presence of disturbed ferrous zones suggests the existence of a dynamic factor that caused deformations in the sediments. Cavities, crevices, cracks, and traces of parching or fragmentation of mineral material can be interpreted as deformations related to the impact of meteorite fragments in non-consolidated soft sediments in the Morasko meteorite nature reserve. Meteorite fragments that left numerous deformed structures most probably constituted meteorite debris that originated from the fragmentation of the meteorite before its impact

Data-driven inference for the spatial scan statistic

<p>Abstract</p> <p>Background</p> <p>Kulldorff's spatial scan statistic for aggregated area maps searches for clusters of cases without specifying their size (number of areas) or geographic location in advance. Their statistical significance is tested while adjusting for the multiple testing inherent in such a procedure. However, as is shown in this work, this adjustment is not done in an even manner for all possible cluster sizes.</p> <p>Results</p> <p>A modification is proposed to the usual inference test of the spatial scan statistic, incorporating additional information about the size of the most likely cluster found. A new interpretation of the results of the spatial scan statistic is done, posing a modified inference question: what is the probability that the null hypothesis is rejected for the original observed cases map with a most likely cluster of size k, taking into account only those most likely clusters of size k found under null hypothesis for comparison? This question is especially important when the p-value computed by the usual inference process is near the alpha significance level, regarding the correctness of the decision based in this inference.</p> <p>Conclusions</p> <p>A practical procedure is provided to make more accurate inferences about the most likely cluster found by the spatial scan statistic.</p

Voronoi distance based prospective space-time scans for point data sets: a dengue fever cluster analysis in a southeast Brazilian town

<p>Abstract</p> <p>Background</p> <p>The Prospective Space-Time scan statistic (PST) is widely used for the evaluation of space-time clusters of point event data. Usually a window of cylindrical shape is employed, with a circular or elliptical base in the space domain. Recently, the concept of Minimum Spanning Tree (MST) was applied to specify the set of potential clusters, through the Density-Equalizing Euclidean MST (DEEMST) method, for the detection of arbitrarily shaped clusters. The original map is cartogram transformed, such that the control points are spread uniformly. That method is quite effective, but the cartogram construction is computationally expensive and complicated.</p> <p>Results</p> <p>A fast method for the detection and inference of point data set space-time disease clusters is presented, the Voronoi Based Scan (VBScan). A Voronoi diagram is built for points representing population individuals (cases and controls). The number of Voronoi cells boundaries intercepted by the line segment joining two cases points defines the Voronoi distance between those points. That distance is used to approximate the density of the heterogeneous population and build the Voronoi distance MST linking the cases. The successive removal of edges from the Voronoi distance MST generates sub-trees which are the potential space-time clusters. Finally, those clusters are evaluated through the scan statistic. Monte Carlo replications of the original data are used to evaluate the significance of the clusters. An application for dengue fever in a small Brazilian city is presented.</p> <p>Conclusions</p> <p>The ability to promptly detect space-time clusters of disease outbreaks, when the number of individuals is large, was shown to be feasible, due to the reduced computational load of VBScan. Instead of changing the map, VBScan modifies the metric used to define the distance between cases, without requiring the cartogram construction. Numerical simulations showed that VBScan has higher power of detection, sensitivity and positive predicted value than the Elliptic PST. Furthermore, as VBScan also incorporates topological information from the point neighborhood structure, in addition to the usual geometric information, it is more robust than purely geometric methods such as the elliptic scan. Those advantages were illustrated in a real setting for dengue fever space-time clusters.</p

Spatial Cluster Detection for Repeatedly Measured Outcomes while Accounting for Residential History

Spatial cluster detection has become an important methodology in quantifying the effect of hazardous exposures. Previous methods have focused on cross-sectional outcomes that are binary or continuous. There are virtually no spatial cluster detection methods proposed for longitudinal outcomes. This paper proposes a new spatial cluster detection method for repeated outcomes using cumulative geographic residuals. A major advantage of this method is its ability to readily incorporate information on study participants relocation, which most cluster detection statistics cannot. Application of these methods will be illustrated by the Home Allergens and Asthma prospective cohort study analyzing the relationship between environmental exposures and repeated measured outcome, occurrence of wheeze in the last 6 months, while taking into account mobile locations