We consider excited random walks (ERWs) on integers in i.i.d. environments with a bounded number of excitations per site. The emphasis is primarily on the critical case for the transition between recurrence and transience which occurs when the total expected drift δ at each site of the environment is equal to 1 in absolute value. Several crucial estimates for ERWs fail in the critical case and ...

– We examine the proposal that a model of the large-scale matter distribution consisting of randomly placed haloes with power-law profile, as opposed to a fractal model, can account for the observed power-law galaxy-galaxy correlations. We conclude that such model, which can actually be considered as a degenerate multifractal model, is not realistic but suggests a new picture of multifractal mo...

The multiscale behavior of a recently reported model for stock markets is presented. It has been shown that indexes of real-world markets display absolute returns with memory properties on a long-time range, a phenomenon known as cluster volatility. The multiscale characteristics of an index are studied by analyzing the power-law scaling of the volatility correlations which display nonunique sc...

BACKGROUND Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible limitation in airflow. A physiological variable--the forced expiratory volume in one second (FEV1)--is often used to grade the severity of COPD. However, patients with COPD have systemic manifestations that are not reflected by the FEV1. We hypothesized that a multidimensional grading system t...

Simple bibliometric indicators, such as average number of citations per publication per researcher, or the recently-proposed Hirsch index (h-index), are nowadays tracked by online repositories including Web-of-Science (WOS) and often affect critical decision making. This work proposes appropriate scaling of the h-index, based on its probability distribution which is calculated for any underlyin...

Recent advances in methods and techniques enable us to develop an interactive overlay to the global map of science based on aggregated citation relations among the 9,162 journals contained in the Science Citation Index and Social Science Citation Index 2009 combined. The resulting mapping is provided by VOSViewer. We first discuss the pros and cons of the various options: cited versus citing, m...

Efficient query processing is one of the basic needs for data mining algorithms. Clustering algorithms, association rule mining algorithms and OLAP tools all rely on efficient query processors being able to deal with high-dimensional data. Inside such a query processor, multidimensional index structures are used as a basic technique. As the implementation of such an index structures is a diffic...

Context: Multidimensional arrays are used by many different algorithms. As such, indexing and broadcasting complex operations over multidimensional arrays are ubiquitous tasks and can be performance limiting. Inquiry: Simultaneously indexing two ormoremultidimensional arrays with different shapes (e.g., copying data from one tensor to another larger, zero padded tensor in anticipation of a conv...

To solve the overlapping search of multidimensional spatial database containing large quantity of objects with dynamic spatial extent, this paper proposes an index structure named Space Grid Tree (SG-Tree) based on Peano Space-Filling Curve (SFC) to index the region of object. By appropriate linearization strategy, the bounding box of a spatial object can be presented by a union of mutually dis...

In the era of huge datasets, the topsearch becomes an effective way to decrease the search time of topobjects. Since we suppose locally accessible data only, the multidimensional indexes containing all attributes together seem to be more effective than a distribution of each attribute to a separate index. Therefore we introduce the topsearch algorithm over grid file – the multidimensional index...