Introducing Accountability to Anonymity Networks

Many anonymous communication (AC) networks rely on routing traffic through proxy nodes to obfuscate the originator of the traffic. Without an accountability mechanism, exit proxy nodes risk sanctions by law enforcement if users commit illegal actions through the AC network. We present BackRef, a generic mechanism for AC networks that provides practical repudiation for the proxy nodes by tracing back the selected outbound traffic to the predecessor node (but not in the forward direction) through a cryptographically verifiable chain. It also provides an option for full (or partial) traceability back to the entry node or even to the corresponding user when all intermediate nodes are cooperating. Moreover, to maintain a good balance between anonymity and accountability, the protocol incorporates whitelist directories at exit proxy nodes. BackRef offers improved deployability over the related work, and introduces a novel concept of pseudonymous signatures that may be of independent interest. We exemplify the utility of BackRef by integrating it into the onion routing (OR) protocol, and examine its deployability by considering several system-level aspects. We also present the security definitions for the BackRef system (namely, anonymity, backward traceability, no forward traceability, and no false accusation) and conduct a formal security analysis of the OR protocol with BackRef using ProVerif, an automated cryptographic protocol verifier, establishing the aforementioned security properties against a strong adversarial model

Familienfreundlichkeit im Mittelstand: Betriebliche Strategien zur besseren Vereinbarkeit von Beruf und Familie

Rund 80 % aller Erwerbstätigen haben familiäre Anforderungen zu erfüllen. Untersuchungen zur familienfreundlichen Personalführung aus den 90er Jahren deuteten jedoch darauf hin, dass es vor allem große Unternehmen sind, die Arbeitsplätze familienfreundlich gestalten. Die Überprüfung der Familienfreundlichkeit mittelständischer Unternehmen in Deutschland ist daher Thema der vorliegenden Studie. Auf der Grundlage einer Befragung von 759 Unternehmen sowie von 23 Einzelfallstudien werden die betriebswirtschaftlichen und personalpolitischen Motive sowie der Erfolg der Maßnahmen bewertet. Es werden zudem rechtliche, branchen- und größenspezifische Aspekte diskutiert, welche die Umsetzung familienfreundlicher Maßnahmen in KMU beeinflussen. Das Qualifikationsniveau der Mitarbeiter und die branchenspezifische Ausgestaltung der Arbeitsplätze erwiesen sich als mitentscheidend für die Wahl familienfreundlicher Maßnahmen. Bei Einfachtätigkeiten sind tendenziell kostengünstige Maßnahmen wie Arbeitszeit- und Urlaubsregelungen üblich. Die Bereitschaft, mit höheren Investitionskosten verbundene Maßnahmen in den Unternehmen einzuführen, steigt mit der Qualifikation der Mitarbeiter. In Deutschland wurde wie in anderen EU-Staaten versucht, den Gedanken der familienfreundlichen Unternehmensführung durch Wettbewerbe und Zertifizierungen zu fördern. Die Publikation listet solche Wettbewerbe und Audits auf und stellt dar, warum deren Bedeutung in mittelständischen Unternehmen nur relativ gering ist. Schließlich wird aufgrund der in den Unternehmen gewonnenen Erfahrungen beschrieben, welche Anforderungen an eine erfolgreiche Einführung von familienfreundlichen Maßnahmen zu stellen sind, wie Implementierungsprobleme in den Unternehmen vermieden werden können und welche Rahmenbedingungen für die Erwerbstätigkeit von Familienmitgliedern zu verbessern sind. --

The effects of exercise and two pre-exercise fluid amounts on cognition

Exercise is associated with elevated mood states and arousal. Observational studies support the claim that exercise can help individuals think more “clearly’ with reports of improved mood and feelings of psychological well-being following exercise. However, laboratory studies have produced equivocal results. The purpose of this study is to examine the effect of exercise intensity and two likely pre-exercise fluid amounts consumed by euhydrated athletes on cognitive performance. Fifteen college age students were randomly assigned to either a 150 ml or a 500 ml fluid condition on the first test day and received the other fluid condition on the second test day. Prior to exercise subjects completed baseline computerized cognitive tests then began a treadmill protocol of three 6 min stages at increasing intensity after which subjects completed cognitive tests. A second treadmill portion started at 7.5 mph for 2 min then speed was increased 0.5 mph every 30 s until voluntary exhaustion and final cognitive testing was completed. Our results demonstrate a facilitation of cognitive function in response to exercise with the exception of the match to sample cognitive test which showed lack of facilitation of cognition in the 500 ml condition at moderate exercise. Our research contributes to the growing field of exercise and its effects on cognition. Specifically working memory cognitive tests showed facilitation with exercise. These results may be applicable to a typical exercising population since our study included a common exercise mode (treadmill) at moderate and high intensities and likely fluid amounts

Noninvasive monitoring of radiotherapy-induced microvascular changes using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in a colorectal tumor model

To examine dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with a macromolecular contrast agent (P792) to visualize effects of radiotherapy (RT) on microvascular leakage in a colorectal cancer model.Journal Articleinfo:eu-repo/semantics/publishe

GraBCas: a bioinformatics tool for score-based prediction of Caspase- and Granzyme B-cleavage sites in protein sequences

Caspases and granzyme B are proteases that share the primary specificity to cleave at the carboxyl terminal of aspartate residues in their substrates. Both, caspases and granzyme B are enzymes that are involved in fundamental cellular processes and play a central role in apoptotic cell death. Although various targets are described, many substrates still await identification and many cleavage sites of known substrates are not identified or experimentally verified. A more comprehensive knowledge of caspase and granzyme B substrates is essential to understand the biological roles of these enzymes in more detail. The relatively high variability in cleavage site recognition sequence often complicates the identification of cleavage sites. As of yet there is no software available that allows identification of caspase and/or granzyme with cleavage sites differing from the consensus sequence. Here, we present a bioinformatics tool ‘GraBCas’ that provides score-based prediction of potential cleavage sites for the caspases 1–9 and granzyme B including an estimation of the fragment size. We tested GraBCas on already known substrates and showed its usefulness for protein sequence analysis. GraBCas is available at

Transcriptome analysis by GeneTrail revealed regulation of functional categories in response to alterations of iron homeostasis in Arabidopsis thaliana

<p>Abstract</p> <p>Background</p> <p>High-throughput technologies have opened new avenues to study biological processes and pathways. The interpretation of the immense amount of data sets generated nowadays needs to be facilitated in order to enable biologists to identify complex gene networks and functional pathways. To cope with this task multiple computer-based programs have been developed. GeneTrail is a freely available online tool that screens comparative transcriptomic data for differentially regulated functional categories and biological pathways extracted from common data bases like KEGG, Gene Ontology (GO), TRANSPATH and TRANSFAC. Additionally, GeneTrail offers a feature that allows screening of individually defined biological categories that are relevant for the respective research topic.</p> <p>Results</p> <p>We have set up GeneTrail for the use of <it>Arabidopsis thaliana</it>. To test the functionality of this tool for plant analysis, we generated transcriptome data of root and leaf responses to Fe deficiency and the Arabidopsis metal homeostasis mutant <it>nas4x-1</it>. We performed Gene Set Enrichment Analysis (GSEA) with eight meaningful pairwise comparisons of transcriptome data sets. We were able to uncover several functional pathways including metal homeostasis that were affected in our experimental situations. Representation of the differentially regulated functional categories in Venn diagrams uncovered regulatory networks at the level of whole functional pathways. Over-Representation Analysis (ORA) of differentially regulated genes identified in pairwise comparisons revealed specific functional plant physiological categories as major targets upon Fe deficiency and in <it>nas4x-1</it>.</p> <p>Conclusion</p> <p>Here, we obtained supporting evidence, that the <it>nas4x-1 </it>mutant was defective in metal homeostasis. It was confirmed that <it>nas4x-1 </it>showed Fe deficiency in roots and signs of Fe deficiency and Fe sufficiency in leaves. Besides metal homeostasis, biotic stress, root carbohydrate, leaf photosystem and specific cell biological categories were discovered as main targets for regulated changes in response to - Fe and <it>nas4x-1</it>. Among 258 differentially expressed genes in response to - Fe and <it>nas4x-1 </it>five functional categories were enriched covering metal homeostasis, redox regulation, cell division and histone acetylation. We proved that GeneTrail offers a flexible and user-adapted way to identify functional categories in large-scale plant transcriptome data sets. The distinguished feature that allowed analysis of individually assembled functional categories facilitated the study of the <it>Arabidopsis thaliana </it>transcriptome.</p

BNDB – The Biochemical Network Database

<p>Abstract</p> <p>Background</p> <p>Technological advances in high-throughput techniques and efficient data acquisition methods have resulted in a massive amount of life science data. The data is stored in numerous databases that have been established over the last decades and are essential resources for scientists nowadays. However, the diversity of the databases and the underlying data models make it difficult to combine this information for solving complex problems in systems biology. Currently, researchers typically have to browse several, often highly focused, databases to obtain the required information. Hence, there is a pressing need for more efficient systems for integrating, analyzing, and interpreting these data. The standardization and virtual consolidation of the databases is a major challenge resulting in a unified access to a variety of data sources.</p> <p>Description</p> <p>We present the Biochemical Network Database (BNDB), a powerful relational database platform, allowing a complete semantic integration of an extensive collection of external databases. BNDB is built upon a comprehensive and extensible object model called BioCore, which is powerful enough to model most known biochemical processes and at the same time easily extensible to be adapted to new biological concepts. Besides a web interface for the search and curation of the data, a Java-based viewer (BiNA) provides a powerful platform-independent visualization and navigation of the data. BiNA uses sophisticated graph layout algorithms for an interactive visualization and navigation of BNDB.</p> <p>Conclusion</p> <p>BNDB allows a simple, unified access to a variety of external data sources. Its tight integration with the biochemical network library BN++ offers the possibility for import, integration, analysis, and visualization of the data. BNDB is freely accessible at <url>http://www.bndb.org</url>.</p