Filters








71 Hits in 1.0 sec

EvenTweet

Hamed Abdelhaq, Christian Sengstock, Michael Gertz
2013 Proceedings of the VLDB Endowment  
Microblogging services such as Twitter, Facebook, and Foursquare have become major sources for information about real-world events. Most approaches that aim at extracting event information from such sources typically use the temporal context of messages. However, exploiting the location information of georeferenced messages, too, is important to detect localized events, such as public events or emergency situations. Users posting messages that are close to the location of an event serve as
more » ... sensors to describe an event. In this demonstration, we present a novel framework to detect localized events in real-time from a Twitter stream and to track the evolution of such events over time. For this, spatio-temporal characteristics of keywords are continuously extracted to identify meaningful candidates for event descriptions. Then, localized event information is extracted by clustering keywords according to their spatial similarity. To determine the most important events in a (recent) time frame, we introduce a scoring scheme for events. We demonstrate the functionality of our system, called Even-Tweet, using a stream of tweets from Europe during the 2012 UEFA European Football Championship.
doi:10.14778/2536274.2536307 fatcat:zwr6msq64zbgjbrmprkj6vrtgy

CONQUER

Christian Sengstock, Michael Gertz
2011 Proceedings of the 20th international conference companion on World wide web - WWW '11  
Many of today's search engines provide autocompletion while the user is typing a query string. This type of dynamic query suggestion can help users to formulate queries that better represent their search intent during Web search interactions. In this paper, we demonstrate our query suggestion system called CONQUER, which allows to efficiently suggest queries for a given partial query and a number of available query context observations. The context-awareness allows for suggesting queries
more » ... d to a given context, e.g., the user location or the time of day. CONQUER uses a suggestion model that is based on the combined probabilities of sequential query patterns and context observations. For this, the weight of a context in a query suggestion can be adjusted online, for example, based on the learned user behavior or user profiles. We demonstrate the functionality of CONQUER based on 6 million queries from an AOL query log using the time of day and the country domain of the clicked URLs in the search result as context observations.
doi:10.1145/1963192.1963305 dblp:conf/www/SengstockG11 fatcat:ivskgcf7rjbh3albqlifq7j4py

Latent contextual indexing of annotated documents

Christian Sengstock, Michael Gertz
2012 Proceedings of the 21st international conference companion on World Wide Web - WWW '12 Companion  
In this paper we propose a simple and flexible framework to index context-annotated documents, e.g., documents with timestamps or georeferences, by contextual topics. A contextual topic is a distribution over document features with a particular meaning in the context domain, such as a repetitive event or a geographic phenomenon. Such a framework supports document clustering, labeling, and search, with respect to contextual knowledge contained in the document collection. To realize the
more » ... we introduce an approach to project documents into a context-feature space. Then, dimensionality reduction is used to extract contextual topics in this context-feature space. The topics can then be projected back onto the documents. We demonstrate the utility of our approach with a case study on georeferenced Wikipedia articles.
doi:10.1145/2187980.2188143 dblp:conf/www/SengstockG12 fatcat:oqlqt26nejheda25ojh5gmtlqm

Online Hot Spot Prediction in Road Networks

Maik Häsner, Conny Junghans, Christian Sengstock, Michael Gertz
2011 Datenbanksysteme für Business, Technologie und Web  
Advancements in GPS-technology have spurred major research and development activities for managing and analyzing large amounts of position data of mobile objects. Data mining tasks such as the discovery of movement patterns, classification and outlier detection in the context of object trajectories, and the prediction of future movement patterns have become basic tools in extracting useful information from such position data. Especially the prediction of future movement patterns of vehicles,
more » ... ed on historical or recent position data, plays an important role in traffic management and planning. In this paper, we present a new approach for the online prediction of so-called hot spots, that is, components of a road network such as intersections that are likely to experience heavy traffic in the near future. For this, we employ an efficient path prediction model for vehicle movements that only utilizes a few recent position data. Using an aggregation model for hot spots, we show how regional information can be derived and connected substructures in a road network can be determined. Utilizing the behavior of such hot spot regions over time in terms of movement or growth, we introduce different types of hot spots and show how they can be determined online. We demonstrate the effectiveness of our approach using a real large-scale road network and different traffic simulation scenarios.
dblp:conf/btw/HasnerJSG09 fatcat:5czvpxmmazcefojypbll7wgkb4

Spatial Interestingness Measures for Co-location Pattern Mining

Christian Sengstock, Michael Gertz, Tran Van Canh
2012 2012 IEEE 12th International Conference on Data Mining Workshops  
Co-location pattern mining aims at finding subsets of spatial features frequently located together in spatial proximity. The underlying motivation is to model the spatial correlation structure between the features. This allows to discover interesting co-location rules (feature interactions) for spatial analysis and prediction tasks. As in association rule mining, a major problem is the huge amount of possible patterns and rules. Hence, measures are needed to identify interesting patterns and
more » ... es. Existing approaches so far focused on finding frequent patterns, patterns including rare features, and patterns occurring in small (local) regions. In this paper, we present a new general class of interestingness measures that are based on the spatial distribution of co-location patterns. These measures allow to judge the interestingness of a pattern based on properties of the underlying spatial feature distribution. The results are different from standard measures like participation index or confidence. To demonstrate the usefulness of these measures, we apply our approach to the discovery of rules on a subset of the OpenStreetMap point-of-interest data.
doi:10.1109/icdmw.2012.116 dblp:conf/icdm/SengstockGC12 fatcat:nermn5qxevfvhanjxnlwlcearm

Latent geographic feature extraction from social media

Christian Sengstock, Michael Gertz
2012 Proceedings of the 20th International Conference on Advances in Geographic Information Systems - SIGSPATIAL '12  
In this work we present a framework for the unsupervised extraction of latent geographic features from georeferenced social media. A geographic feature represents a semantic dimension of a location and can be seen as a sensor that measures a signal of geographic semantics. Our goal is to extract a small number of informative geographic features from social media, to describe and explore geographic space, and for subsequent spatial analysis, e.g., in market research. We propose a framework that,
more » ... first, transforms the unstructured and noisy geographic information in social media into a high-dimensional multivariate signal of geographic semantics. Then, we use dimensionality reduction to extract latent geographic features. We conduct experiments using two large-scale Flickr data sets covering the LA area and the US. We show that dimensionality reduction techniques extracting sparse latent features find dimensions with higher informational value. In addition, we show that prior normalization can be used as a parameter in the exploration process to extract features representing different geographic characteristics, that is, landmarks, regional phenomena, or global phenomena. 1 The use of the term feature stems from its usage in the information retrieval literature. DEFINITIONS AND PROBLEM STATE-MENT In this section we introduce some basic definitions and formulate the problems of exploratory geographic feature discovery and latent geographic feature extraction.
doi:10.1145/2424321.2424342 dblp:conf/gis/SengstockG12 fatcat:lj42bhjwqraw5crtt57wlbtgxi

Spatio-temporal characteristics of bursty words in Twitter streams

Hamed Abdelhaq, Michael Gertz, Christian Sengstock
2013 Proceedings of the 21st ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems - SIGSPATIAL'13  
This paper studies the problem of recommending new venues to users who participate in location-based social networks (LBSNs). As an increasingly larger number of users partake in LBSNs, the recommendation problem in this setting has attracted significant attention in research and in practical applications. The detailed information about past user behavior that is traced by the LBSN differentiates the problem significantly from its traditional settings. The spatial nature in the past user
more » ... r and also the information about the user social interaction with other users, provide a richer background to build a more accurate and expressive recommendation model. Although there have been extensive studies on recommender systems working with user-item ratings, GPS trajectories, and other types of data, there are very few approaches that exploit the unique properties of the LBSN user check-in data. In this paper, we propose algorithms that create recommendations based on four factors: a) past user behavior (visited places), b) the location of each venue, c) the social relationships among the users, and d ) the similarity between users. The proposed algorithms outperform traditional recommendation algorithms and other approaches that try to exploit LBSN information. To design our recommendation algorithms we study the properties of two real LBSNs, Brightkite and Gowalla, and analyze the relation between users and visited locations. An experimental evaluation using data from these LBSNs shows that the exploitation of the additional geographical and social information allows our proposed techniques to outperform the current state of the art.
doi:10.1145/2525314.2525354 dblp:conf/gis/AbdelhaqGS13 fatcat:btjmprcqubeglngb5qn4tcwikq

Design of a dual species atom interferometer for space

Thilo Schuldt, Christian Schubert, Markus Krutzik, Lluis Gesa Bote, Naceur Gaaloul, Jonas Hartwig, Holger Ahlers, Waldemar Herr, Katerine Posso-Trujillo, Jan Rudolph, Stephan Seidel, Thijs Wendrich (+45 others)
2015 Experimental astronomy (Print)  
Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption,
more » ... al robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species ^85Rb/^87Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for 10^-11 mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (819 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.
doi:10.1007/s10686-014-9433-y fatcat:qzdsij2jxvfvthiy7fachrwcqi

Patterns of Cultural Inclusion and Exclusion in American Society: The Case of Chaldean Americans

Lanouar Ben Hafsa
2018 International Journal of Social Science Studies  
(Sengstock, 1982: 60) .  ...  of their Christian faith as a unifying force.  ... 
doi:10.11114/ijsss.v6i8.3475 fatcat:p4wifh47q5a7vogx3legm2d4eu

PVP-coated, negatively charged silver nanoparticles: A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments

Sebastian Ahlberg, Alexandra Antonopulos, Jörg Diendorf, Ralf Dringen, Matthias Epple, Rebekka Flöck, Wolfgang Goedecke, Christina Graf, Nadine Haberl, Jens Helmlinger, Fabian Herzog, Frederike Heuer (+25 others)
2014 Beilstein Journal of Nanotechnology  
PVP-capped silver nanoparticles with a diameter of the metallic core of 70 nm, a hydrodynamic diameter of 120 nm and a zeta potential of −20 mV were prepared and investigated with regard to their biological activity. This review summarizes the physicochemical properties (dissolution, protein adsorption, dispersability) of these nanoparticles and the cellular consequences of the exposure of a broad range of biological test systems to this defined type of silver nanoparticles. Silver
more » ... dissolve in water in the presence of oxygen. In addition, in biological media (i.e., in the presence of proteins) the surface of silver nanoparticles is rapidly coated by a protein corona that influences their physicochemical and biological properties including cellular uptake. Silver nanoparticles are taken up by cell-type specific endocytosis pathways as demonstrated for hMSC, primary T-cells, primary monocytes, and astrocytes. A visualization of particles inside cells is possible by X-ray microscopy, fluorescence microscopy, and combined FIB/SEM analysis. By staining organelles, their localization inside the cell can be additionally determined. While primary brain astrocytes are shown to be fairly tolerant toward silver nanoparticles, silver nanoparticles induce the formation of DNA double-strand-breaks (DSB) and lead to chromosomal aberrations and sister-chromatid exchanges in Chinese hamster fibroblast cell lines (CHO9, K1, V79B ). An exposure of rats to silver nanoparticles in vivo induced a moderate pulmonary toxicity, however, only at rather high concentrations. The same was found in precision-cut lung slices of rats in which silver nanoparticles remained mainly at the tissue surface. In a human 3D triple-cell culture model consisting of three cell types (alveolar epithelial cells, macrophages, and dendritic cells), adverse effects were also only found at high silver concentrations. The silver ions that are released from silver nanoparticles may be harmful to skin with disrupted barrier (e.g., wounds) and induce oxidative stress in skin cells (HaCaT). In conclusion, the data obtained on the effects of this well-defined type of silver nanoparticles on various biological systems clearly demonstrate that cell-type specific properties as well as experimental conditions determine the biocompatibility of and the cellular responses to an exposure with silver nanoparticles.
doi:10.3762/bjnano.5.205 pmid:25383306 pmcid:PMC4222445 fatcat:nvdkf7acrrcvbbvwxjnubgrxma

Page 434 of Association of the Bar of the City of New York. The Record of the Association of the Bar of the City of New York Vol. 16, Issue 7 [page]

1961 Association of the Bar of the City of New York. The Record of the Association of the Bar of the City of New York  
Life, death and the law; law and Christian morals in England and the United States. Bloomington, Indiana Univ. Press. 1961. 375p- Schafer, Stephen. Restitution to victims of crime.  ...  Sengstock, Frank $. Annexation: a solution to the metropolitan area prob- lem. Ann Arbor, Michigan Legal Publications. 1960. 120p. Sheridan, L. A. Malaya and Singapore; the Borneo territories.  ... 

Page 3 of Catholic School Journal Vol. 67, Issue 10 [page]

1967 Catholic School Journal  
Sengstock, Jr. Science on Saturday Nancy Dixon Science Outdoors Some Creative Activities in Elementary Science Edward F. DeRoche, Ph.D.  ...  Free Science Teaching Aids Amold Hagen ELEMENTARY SECTION Christian Challenge in Primary Grades Sister Juanita Pohl, O.P.  ... 

Kuronismen im Halleschen sog. Richter-Wörterbuch

Christiane Schiller
2014 Res Humanitariae  
Schiller Kuronismen im Halleschen sog. richter-Wörterbuch christiane Schiller Kuronismen im Halleschen sog. richter-Wörterbuch christiane Schiller Kuronismen im Halleschen sog. richter-Wörterbuch christiane  ...  Spurts (korr. aus Sparts). christiane Schiller Kuronismen im Halleschen sog. richter-Wörterbuch christiane Schiller Kuronismen im Halleschen sog. richter-Wörterbuch  ...  Sie ist überliefert etwa für den Bibelübersetzer, Johannes Bretke (1536-1602), Pfarrer in Labiau und Königsberg (Viktor Falkenhahn 1941, 50f.) und für Lazarus Sengstock (1562-1621), Pfarrer in ruß, Memel  ... 
doi:10.15181/rh.v0i15.837 fatcat:5ndd23qcrvhs7lxxyly7kb5dha

iSense: A Technology Platform for Cold Atom Based Quantum Technologies

Kai Bongs, Jon Malcolm, Clemens Ramelloo, Lingxiao Zhu, Vincent Boyer, Tristan Valenzuela, Jessica Maclean, Anton Piccardo-Selg, Chris Mellor, Thomas Fernholz, Mark Fromhold, Peter Krüger (+30 others)
2014 Research in Optical Sciences   unpublished
A breakthrough in cold atom quantum technology is hindered by a bottleneck in the supporting technologies. We discuss a cold atom technology platform developed within the European iSense project, aiming at a gravimeter as demonstrator.
doi:10.1364/qim.2014.qtu3b.1 fatcat:5vewdunq3ncizo6t3qf25xj5ri

Page 5040 of Psychological Abstracts Vol. 88, Issue 12 [page]

2001 Psychological Abstracts  
., 35850 Schommer-Aikins, Marlene, 36384 Schén, Peter-Christian, 35882 Schénpflug, Ute, 36499 Schorger, John R., 38295 Schott, Geoffrey D., 37293 Schradin, Carsten, 35971 Schramm, Nicole L., 36004 Schramm-Nielsen  ...  36481 Sellars, Cameron, 38110 AUTHOR INDEX Sellers, Alfred 1 , 35604 Sellien, Heike, 36140 Sellnow, Timothy L., 38496 Semeniuk, Bob, 37546 Semrud-C on, —— 37497 Senanayake, B., Sénéchal, = Tay 36369 Sengstock  ... 
« Previous Showing results 1 — 15 out of 71 results