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Muhlfeld S.,Heinrich Heine University Düsseldorf | Domanova O.,Fraunhofer Institute for Applied Information Technology | Domanova O.,RWTH Aachen | Domanova O.,Bonn Aachen International Center for Information Technology | And 8 more authors.
Hepatology | Year: 2012

The sodium taurocholate cotransporting polypeptide (Ntcp) is the major bile salt uptake transporter at the sinusoidal membrane of hepatocytes. Short-term feedback regulation of Ntcp by primary bile salts has not yet been investigated in vivo. Subcellular localization of Ntcp was analyzed in Ntcp-transfected HepG2-cells by flow cytometry and in immunofluorescence images from tissue sections by a new automated image analysis method. Net bile salt uptake was investigated in perfused rat liver by a pulse chase technique. In Flag-Ntcp-EGFP (enhanced green fluorescent protein) expressing HepG2-cells, taurochenodeoxycholate (TCDC), but not taurocholate (TC), induced endocytosis of Ntcp. TCDC, but not TC, caused significant internalization of Ntcp in perfused rat livers, as shown by an increase in intracellular Ntcp immunoreactivity, whereas Bsep distribution remained unchanged. These results correlate with functional studies. Rat livers were continuously perfused with 100 μmol/L of TC. 25 μmol/L of TCDC, taurodeoxycholate (TDC), tauroursodeoxycholate (TUDC), or TC were added for 30 minutes, washed out, followed by a pulse of 3[H]-TC. TCDC, but not TDC, TUDC, or TC significantly increased the amount of 3[H]-TC in the effluent, indicating a reduced sinusoidal net TC uptake. This effect was sensitive to chelerythrine (protein kinase C inhibitor) and cypermethrin (protein phosphatase 2B inhibitor). Phosphoinositide 3-kinase (PI3K) inhibitors had an additive effect, whereas Erk1/2 (extracellular signal activated kinase 1/2), p38MAPK, protein phosphatase 1/2A (PP1/2A), and reactive oxygen species (ROS) were not involved. Conclusion: TCDC regulates bile salt transport at the sinusoidal membrane by protein kinase C- and protein phosphatase 2B-mediated retrieval of Ntcp from the plasma membrane. During increased portal bile salt load this mechanism may adjust bile salt uptake along the acinus and protect periportal hepatocytes from harmful bile salt concentrations. © 2012 American Association for the Study of Liver Diseases.

Shamili A.S.,Bonn Aachen International Center for Information Technology | Bauckhage C.,Bonn Aachen International Center for Information Technology | Alpcan T.,TU Berlin
Proceedings - International Conference on Pattern Recognition | Year: 2010

This paper presents a distributed Support Vector Machine (SVM) algorithm in order to detect malicious software (malware) on a network of mobile devices. The light-weight system monitors mobile user activity in a distributed and privacy-preserving way using a statistical classification model which is evolved by training with examples of both normal usage patterns and unusual behavior. The system is evaluated using the MIT reality mining data set. The results indicate that the distributed learning system trains quickly and performs reliably. Moreover, it is robust against failures of individual components. © 2010 IEEE.

Sarier N.D.,Bonn Aachen International Center for Information Technology
Journal of Network and Computer Applications | Year: 2010

Recently, Bringer et al. proposed a new approach for remote biometric based verification, which consists of a hybrid protocol that distributes the server side functionality in order to detach the biometric data storage from the service provider. Besides, a new security model is defined using the notions of Identity and Transaction Privacy, which guarantee the privacy of the identity-biometrics relationship under the assumption of non-colluding servers. However, due to the high communication and computational costs, the systems following this model cannot be implemented for large scale biometric systems. In this paper, we describe an efficient multi-factor biometric verification system with improved accuracy and lower complexity by considering the range information of every component of the user biometrics separately. Also, the new scheme is provably secure based on the security model of Bringer et al and implements a different database storage that eliminates the disadvantages of encrypted biometric templates in terms of ciphertext expansion. Also, we evaluate different Private Information Retrieval (PIR) schemes applicable for this setting and propose a practical solution for our scheme that reduces the computation costs dramatically. Finally, we compare our results with existing provably secure schemes and achieve reduced computational cost and database storage cost due to the single storage of the common features of the users in the system and amortization of the time complexity of the PIR. © 2010 Elsevier Ltd. All rights reserved.

Dong T.,Bonn Aachen International Center for Information Technology | Cremers A.B.,Bonn Aachen International Center for Information Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

It is not easy for western people to learn Chinese. Native German speakers find it difficult to understand how Chinese sentences convey meanings without using cases. Statistical machine translation tools may deliver correct German-Chinese translations, but would not explain educational matters. This article reviews some interdisciplinary research on bilingualism, and expounds on how translation is carried out through cross-linguistic cue switching processes. Machine translation approaches are revisited from the perspective of cue switching concluding that: the word order cue is explicitly simulated in all machine translation approaches, and the case cue being implicitly simulated in statistical machine translation approaches can be explicitly simulated in rule-based and example-based machine translation approaches. A convergent result of machine translation research is to advocate an explicit deep-linguistic representation. Here, a novel machine translation method is motivated by blending existing machine translation methods from the viewpoint of cue-switching, and is firstly aimed as an educational tool. This approach takes a limited amount of German-Chinese translations in textbooks as examples, whose cues can be manually obtained, and for which we have developed MultiNet-like deep linguistic representations and cross-linguistic cue-switching processes. Based on this corpus, our present tool is aimed at helping native German speakers to learn Chinese more efficiently, and shall later be expanded to a more comprehensive machine translation system. © 2014 Springer-Verlag Berlin Heidelberg.

Sarier N.D.,Bonn Aachen International Center for Information Technology
Security and Communication Networks | Year: 2011

Recently, Sarier 1 proposed an efficient biometric Identity Based Encryption (IBE) scheme called BIO-IBE using the Sakai Kasahara Key Construction and proved its security in the Random Oracle Model (ROM) based on the well-exploited k-BDHI computational problem. Despite its efficiency compared to other fuzzy IBE systems implemented for biometric identities, BIO-IBE is not secure against a new type of denial of service (DoS) attack that we present. In this context, we describe a new biometric IBE scheme and show that our scheme is immune against this attack due to the signature applied on the public value PAR of the user. This way, the sender can detect whether PAR of the receiver that is stored publicly is modified by an active adversary, thus the generation of a ciphertext based on a wrong identity is avoided. The main difference of the new scheme is the structure of the key generation algorithm, where a unique biometric identity string ID obtained from the biometric attributes is used instead of picking a different polynomial for each user as in other fuzzy IBE schemes. In addition to the well-defined security model for current fuzzy IBE schemes, we describe a stronger security model and prove the security of our scheme in this framework achieving a better reduction cost compared to BIO-IBE. Finally, our scheme provides security against DoS attacks and better efficiency in terms of the key generation and decryption algorithms compared to the existing fuzzy IBE schemes. © 2009 John Wiley & Sons, Ltd.

Sarier N.D.,Bonn Aachen International Center for Information Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

In this paper, we describe a new biometric Identity Based Signature (IBS) scheme based on the Sakai Kasahara Key Construction and prove its security in the framework of a stronger security model compared to exisiting adversarial models. Besides, we present a new type of a denial of service (DoS) attack and evaluate existing biometric IBS schemes in this context. Based on the recently defined privacy notions, we show that our scheme achieves weak signer-attribute privacy and the security is reduced to the k-DHI computational problem in the ROM with an efficient reduction. Finally, our scheme is compared to other error tolerant signature schemes and shown to be much more efficient in terms of its each phase. © 2010 Springer-Verlag.

Sarier N.D.,Bonn Aachen International Center for Information Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

In this paper, we present a novel framework for the generic construction of biometric Identity Based Encryption (IBE) schemes, which do not require bilinear pairings and result in more efficient schemes than existing fuzzy IBE systems implemented for biometric identities. Also, we analyze the security properties that are specific to biometric IBE namely anonymity and identity privacy. Considering these notions, we present generic constructions for biometric IBE and ID-KEM based on weakly secure anonymous IBE schemes, error correcting codes and generic conversion schemes. Finally, we describe concrete applications of our framework and compare them to the existing fuzzy IBE systems in terms of time complexity. © IFIP International Federation for Information Processing 2010.

Gast M.,University of Bonn | Gast M.,Bonn Aachen International Center for Information Technology | Hauptmann M.,University of Bonn
Theoretical Computer Science | Year: 2014

In this paper we construct an approximation algorithm for the Minimum Vertex Cover (Min-VC) problem with an expected approximation ratio of 2-ζ(β)-1-12β2βζ(β-1) ζ(β) for random power-law graphs in the P(α,β) model due to Aiello et al. Here ζ(β) is the Riemann zeta function of β. We obtain this result by combining the Nemhauser and Trotter approach for Min-VC with a new deterministic rounding procedure which achieves an approximation ratio of 32 on a subset of low degree vertices for which the expected contribution to the cost of the associated linear program is sufficiently large. © 2013 Elsevier B.V.

Gurulingappa H.,Fraunhofer Institute for Algorithms and Scientific Computing | Gurulingappa H.,Bonn Aachen International Center for Information Technology | Rajput A.M.,Merck KGaA | Roberts A.,University of Sheffield | And 4 more authors.
Journal of Biomedical Informatics | Year: 2012

A significant amount of information about drug-related safety issues such as adverse effects are published in medical case reports that can only be explored by human readers due to their unstructured nature. The work presented here aims at generating a systematically annotated corpus that can support the development and validation of methods for the automatic extraction of drug-related adverse effects from medical case reports. The documents are systematically double annotated in various rounds to ensure consistent annotations. The annotated documents are finally harmonized to generate representative consensus annotations. In order to demonstrate an example use case scenario, the corpus was employed to train and validate models for the classification of informative against the non-informative sentences. A Maximum Entropy classifier trained with simple features and evaluated by 10-fold cross-validation resulted in the F1 score of 0.70 indicating a potential useful application of the corpus. © 2012 Elsevier Inc..

Fluck J.,Fraunhofer Institute for Algorithms and Scientific Computing | Hofmann-Apitius M.,Fraunhofer Institute for Algorithms and Scientific Computing | Hofmann-Apitius M.,Bonn Aachen International Center for Information Technology
Drug Discovery Today | Year: 2014

Scientific communication in biomedicine is, by and large, still text based. Text mining technologies for the automated extraction of useful biomedical information from unstructured text that can be directly used for systems biology modelling have been substantially improved over the past few years. In this review, we underline the importance of named entity recognition and relationship extraction as fundamental approaches that are relevant to systems biology. Furthermore, we emphasize the role of publicly organized scientific benchmarking challenges that reflect the current status of text-mining technology and are important in moving the entire field forward. Given further interdisciplinary development of systems biology-orientated ontologies and training corpora, we expect a steadily increasing impact of text-mining technology on systems biology in the future. © 2013 Elsevier Ltd.

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