Report on prototype implementation of Pausanias

Classic web search engines, such as Google and Yahoo, provide efficient algorithms for retrieval of ranked search results given a set of keywords. However, there are also applications that provide the user the opportunity to search using geotagged criteria. These applications are Google Maps, Bing Maps etc. Such applications depict points of interest on the map and combine their location with the keywords provided by the associated document(s). These queries are so called spatial queries. Although in many cases spatial constraints seem to suffice, sometimes there is a need to combine spatial and textual information to find points of interests. These queries are called Spatio-Textual Queries. There is an active research interest in spatio-textual queries and more specifically in the efficient retrieval of topK Spatio-Textual Queries. This project employs 5 different queries ranging from simple Boolean Spatial Range Queries to TopK Spatio-Textual Range Queries. In this way the user will be able to choose among 5 queries to satisfy his/her constraints. In the following, there will be an explanation of the data structure and the algorithms that Pausanias employed

Ranked Spatial-keyword Search over Web-accessible Geotagged Data: State of the Art

Search engines, such as Google and Yahoo!, provide efficient retrieval and ranking of web pages based on queries consisting of a set of given keywords. Recent studies show that 20% of all Web queries also have location constraints, i.e., also refer to the location of a geotagged web page. An increasing number of applications support location based keyword search, including Google Maps, Bing Maps, Yahoo! Local, and Yelp. Such applications depict points of interest on the map and combine their location with the keywords provided by the associated document(s). The posed queries consist of two conditions: a set of keywords and a spatial location. The goal is to find points of interest with these keywords close to the location. We refer to such a query as spatial-keyword query. Moreover, mobile devices nowadays are enhanced with built-in GPS receivers, which permits applications (such as search engines or yellow page services) to acquire the location of the user implicitly, and provide location-based services. For instance, Google Mobile App provides a simple search service for smartphones where the location of the user is automatically captured and employed to retrieve results relevant to her current location. As an example, a search for ”pizza” results in a list of pizza restaurants nearby the user. Given the popularity of spatial-keyword queries and their wide applicability in practical scenarios, it is critical to (i) establish mechanisms for efficient processing of spatial-keyword queries, and (ii) support more expressive query formulation by means of novel 1 query types. Although studies on both keyword search and spatial queries do exist, the problem of combining the search capabilities of both simultaneously has received little attention

Report on requirement analysis and design of PAUSANIAS

Nowadays an increasing amount of web-accessible information on spatial objects becomes available to the public every day. Apart from the spatial location of an object (e.g., a point of interest), additional descriptive information typically includes textual description as well as various ratings, often user generated. Modern applications employ spatio-textual queries, which take into account both the spatial location of an object and its textual similarity to retrieve the most relevant objects. However, existing applications provide a limited functionality to the users. For example, several meaningful queries cannot be expressed by existing approaches and motivate our novel prototype system. The goal of our research is to introduce a novel framework, called Pausanias, for supporting ranked spatial-keyword search over web-accessible geotagged data. In this deliverable, we provide an analysis of requirements that should be fulfilled by the proposed prototype and a concise description of the system design of Pausanias

PAUSANIAS: Final activity report

Search engines, such as Google and Yahoo!, provide efficient retrieval and ranking of web pages based on queries consisting of a set of given keywords. Recent studies show that 20% of all Web queries also have location constraints, i.e., also refer to the location of a geotagged web page. An increasing number of applications support location-based keyword search, including Google Maps, Bing Maps, Yahoo! Local, and Yelp. Such applications depict points of interest on the map and combine their location with the keywords provided by the associated document(s). The posed queries consist of two conditions: a set of keywords and a spatial location. The goal is to find points of interest with these keywords close to the location. We refer to such a query as spatial-keyword query. Moreover, mobile devices nowadays are enhanced with built-in GPS receivers, which permits applications (such as search engines or yellow page services) to acquire the location of the user implicitly, and provide location-based services. For instance, Google Mobile App provides a simple search service for smartphones where the location of the user is automatically captured and employed to retrieve results relevant to her current location. As an example, a search for pizza results in a list of pizza restaurants nearby the user. In this research project, we studied how preference queries can be extended for supporting also keywords. To this end we first studied preference queries in order to establish techniques that can be extended for supporting keywords (Chapter 1). Moreover, we proposed Top-k Spatio-Textual Preference Queries and proposed a novel indexing scheme and two algorithms for supporting efficient query processing (Chapter 2). We also studied the problem of maximizing the influence of spatio-textual objects based on reverse top-k queries and keyword selection (Chapter 3). Finally, we analyze the properties of geotagged photos of Flickr, and propose novel location-aware tag recommendation methods (Chapter 4)

Report on novel spatial-keyword search techniques

Nowadays an increasing amount of web-accessible information on spatial objects becomes available to the public every day. Apart from the spatial location of an object (e.g., a point of interest), additional descriptive information typically includes textual description as well as various ratings, often user generated. Modern applications employ spatio-textual queries, which take into account both the spatial location of an object and its textual similarity to retrieve the most relevant objects. However, existing applications provide a limited functionality to the users. For example, several meaningful queries cannot be expressed by existing approaches and motivate our novel prototype system. In the first chapter, we address this limitation by supporting ranked retrieval of objects of interest by taking into account the quality of facilities in their vicinity, but also their textual similarity to user defined keywords. In the second chapter, we analyze the properties of geotagged photos of Flickr, and propose novel location-aware tag recommendation methods. Both of the above techniques are novel spatial-keyword search methods

Stream Processing Languages in the Big Data Era

International audienc

Χειρισμός των εμποδίων στο χώρο και αντίληψη των μεγεθών από τους ασθενείς με νόσο Πάρκινσον

Εισαγωγή: Οι ασθενείς που πάσχουν από νόσο του Πάρκινσον θεωρείται ότι έχουν διαταραχή στην οπτικοχωρική λειτουργία. Πολλοί από αυτούς εμφανίζουν το φαινόμενο του «παγώματος της βάδισης» (Freezing Of Gait, FOG). Oι περισσότερες από τις υπάρχουσες πειραματικές μελέτες που προσεγγίζουν τη φύση του ελλείμματος αυτού περιλαμβάνουν κινητικά στοιχεία (motor components). Η παρούσα έρευνα επιδιώκει να συσχετίσει τις ενδεχόμενες οπτικοχωρικές διαταραχές των ασθενών με νόσο του Πάρκινσον με το φαινόμενο του παγώματος και να συμβάλει στη διερεύνηση της φύσεως των οπτικοχωρικών αυτών διαταραχών, απομονώνοντας την εμπλοκή του κινητικού στοιχείου όσο το δυνατόν περισσότερο. Το ερώτημα είναι εάν το πάγωμα είναι καθαυτό κινητικό έλλειμμα ή εάν οφείλεται σε λανθασμένη αντίληψη των χωρικών ερεθισμάτων του περιβάλλοντος. Μέθοδος-Υλικά: Η αξιολόγηση της νοητικής κατάστασης των συμμετεχόντων έγινε με το Montreal Cognitive Assessment (MoCA). Συγκρίθηκε μία ομάδα ασθενών με νόσο του Πάρκινσον ως προς την επίδοση της σε δύο δοκιμασίες με χρήση εικονικών εμποδίων και σε μία δοκιμασία σύγκρισης μεγεθών με τις επιδόσεις στις δοκιμασίες ενός εξισωμένου δείγματος πληθυσμού χωρίς νευρολογικές παθήσεις. Αποτελέσματα: Υπάρχουν σημαντικές διαφορές μεταξύ των δύο ομάδων στην επίδοση στη δοκιμασία εμποδίων. Στη δοκιμασία σύγκρισης μεγεθών δεν υπήρξαν στατιστικώς σημαντικές διαφορές μεταξύ των δύο ομάδων. Οι ασθενείς με νόσο του Πάρκινσον είχαν στατιστικά μεγαλύτερους λανθάνοντες χρόνους και στις δύο δοκιμασίες. Συμπεράσματα: Οι ασθενείς με νόσο του Πάρκινσον έχουν μεγαλύτερους λανθάνοντες χρόνους από τους υγιείς και στις δύο δοκιμασίες αλλά αυτή η καθυστέρηση δεν διορθώνει την επίδοση τους στις δοκιμασίες εκτίμησης αποστάσεων και πλάτους. Η επίδοσή τους στην αντιληπτική δοκιμασία σύγκρισης μεγεθών δεν διαφέρει από της ομάδας ελέγχου και ίσως να μην εξηγεί την χειρότερη επίδοσή τους στη δοκιμασία των εμποδίων.Introduction: Patients suffering from Parkinson’s disease are considered to have deficits in visual-spatial function. Many of these patients present the “Freezing of Gait” symptom. Most of the existing experimental studies that have approached the nature of this deficit include motor components. The present research attempts to correlate potential visual-spatial deficits of patients with Parkinson’s disease with the FOG phenomenon, and thus contribute to the exploration of the nature of these visual-spatial disorders, by isolating the involvement of the motor element as much as possible. The question raised is whether the freezing is a motor deficit per se, or whether it is attributable to the perception of the spatial stimuli of the environment. Method-Materials: The Montreal Cognitive Assessment (MoCA) was implemented for the cognitive assessment of the participants. A group of Parkinson’s disease patients was compared regarding their performance in two tasks involving visual obstacles (perception of distance and width) and one size (comparison) task with the performances of an equalized sample group with no neurological conditions. Results-Outcomes: The differences between the two groups’ performances regarding the obstacles test are substantial. Regarding the size comparison task there were no significant statistical differences between the two groups. The Parkinson’s disease patients have more response times / latency compared to the healthy participants in both tests, but this delay does not compensate for their performance in the perception of distance and width (obstacles task). Patients’ performance in the cognitive test of size (comparison) task is no different from that of the control group and this may not account for their lower performance in the obstacles task