University of Mannheim

About: University of Mannheim is a education organization based out in Mannheim, Germany. It is known for research contribution in the topics: Context (language use) & Politics. The organization has 4448 authors who have published 12918 publications receiving 446557 citations. The organization is also known as: Uni Mannheim & UMA.

Comparative branching-time semantics for Markov chains

Abstract: This paper presents various semantics in the branching-time spectrum of discrete-time and continuous-time Markov chains (DTMCs and CTMCs). Strong and weak bisimulation equivalence and simulation preorders are covered and are logically characterized in terms of the temporal logics Probabilistic Computation Tree Logic (PCTL) and Continuous Stochastic Logic (CSL). Apart from presenting various existing branching-time relations in a uniform manner, this paper presents the following new results: (i) strong simulation for CTMCs, (ii) weak simulation for CTMCs and DTMCs, (iii) logical characterizations thereof (including weak bisimulation for DTMCs), (iv) a relation between weak bisimulation and weak simulation equivalence, and (v) various connections between equivalences and pre-orders in the continuous-and discrete-time setting. The results are summarized in a branching-time spectrum for DTMCs and CTMCs elucidating their semantics as well as their relationship.

Identifying Cross-Channel Dissynergies for Multichannel Service Providers

Abstract: In this article, the authors propose that in a multichannel environment, evaluative conflicts (dissynergies) between service channels exist. Building on status quo bias theory, they develop a model that relates offline channel satisfaction to perceptions about a new self-service channel. Data were collected from 639 customers currently using offline investment banking. Results show that offline channel satisfaction reduces the perceived usefulness and enhances the perceived risk of the online channel. These inhibiting effects represent a status quo bias. Trust in the bank shows both adoption-enhancing effects and an adoption-inhibiting effect. Finally, the negative relationship between offline channel satisfaction and perceived usefulness is significantly stronger for men, older people, and less experienced Internet users. This study has both theoretical and managerial relevance as it helps to understand consumer behavior in multichannel environments and provides implications for the design of multichannel service strategies.

The Costs of Being Private: Evidence from the Loan Market

Abstract: Using a new dataset of UK-syndicated loans, we document a significant loan cost disadvantage incurred by privately held firms. For identification, we use the distance of a firm's headquarters to London's capital markets as a plausibly exogenous variation in corporate structure (i.e., public/private) choice. We analyze the channels of the loan cost disadvantage of being private by documenting the importance of: the higher costs of information production, the lower bargaining power, the differences in ownership structure, and the differences in secondary market trading. Interestingly, we find no evidence that lenders price expected future performance into the loan spread differential. The Author 2011. Published by Oxford University Press on behalf of The Society for Financial Studies. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com., Oxford University Press.

Automatic text segmentation and text recognition for video indexing

Abstract: Efficient indexing and retrieval of digital videois an important function of video databases. One powerfulindex for retrieval is the text appearing in them. It enablescontent-based browsing. We present our new methods forautomatic segmentation of text in digital videos. The algorithms we propose make use of typical characteristics of textin videos in order to enable and enhance segmentation performance. The unique features of our approach are the tracking of characters and words over their complete duration ofoccurrence in a video and the integration of the multiplebitmaps of a character over time into a single bitmap. Theoutput of the text segmentation step is then directly passedto a standard OCR software package in order to translate thesegmented text into ASCII. Also, a straightforward indexingand retrieval scheme is introduced. It is used in the experiments to demonstrate that the proposed text segmentationalgorithms together with existing text recognition algorithmsare suitable for indexing and retrieval of relevant video sequences in and from a video database. Our experimentalresults are very encouraging and suggest that these algorithms can be used in video retrieval applications as well asto recognize higher level semantics in videos.

Neoadjuvant Imatinib in Locally Advanced Gastrointestinal Stromal Tumors (GIST): The EORTC STBSG Experience

Abstract: Preoperative imatinib therapy of locally advanced GIST may facilitate resection and decrease morbidity of the procedure. We have pooled databases from 10 EORTC STBSG sarcoma centers and analyzed disease-free survival (DFS) and disease-specific survival (DSS) in 161 patients with locally advanced, nonmetastatic GISTs who received neoadjuvant imatinib. OS was calculated from start of imatinib therapy for locally advanced disease until death or last follow-up (FU) after resection of the GIST. DFS was calculated from date of resection to date of disease recurrence or last FU. Median FU time was 46 months. The primary tumor was located in the stomach (55 %), followed by rectum (20 %), duodenum (10 %), ileum/jejunum/other (11 %), and esophagus (3 %). The tumor resection after preoperative imatinib (median time on therapy, 40 weeks) was R0 in 83 %. Only two patients have demonstrated disease progression during neoadjuvant therapy. Five-year DSS/DFS rates were 95/65 %, respectively, median OS was 104 months, and median DFS was not reached. There were 56 % of patients who continued imatinib after resection. Thirty-seven GIST recurrences were diagnosed (only 5 local relapses). The most common mutations affected exon 11 KIT (65 %). Poorer DFS was related to primary tumor location in small bowel and lack of postoperative therapy with imatinib. Our analysis comprising the largest group of GIST patients treated with neoadjuvant imatinib in routine practice indicates excellent long-term results of combined therapy in locally advanced GISTs.