Secure Integration of Desktop Grids and Compute Clusters Based on Virtualization and Meta-Scheduling

Reducing the cost for business or scientific computations, is a commonly expressed goal in today’s companies. Using the available computers of local employees or the outsourcing of such computations are two obvious solutions to save money for additional hardware. Both possibilities exhibit security related disadvantages, since the deployed software and data can be copied or tampered if appropriate countermeasures are not taken. In this paper, an approach is presented to let a local desktop machines and remote cluster resources be securely combined into a singel Grid environment. Solutions to several problems in the areas of secure virtual networks, meta-scheduling and accessing cluster schedulers from desktop Grids are proposed

Origin, differentiation and function of intestinal macrophages

Macrophages are increasingly recognized as essential players in the maintenance of intestinal homeostasis and as key sentinels of the intestinal immune system. However, somewhat paradoxically, they are also implicated in chronic pathologies of the gastrointestinal tract, such as inflammatory bowel disease (IBD) and are therefore considered potential targets for novel therapies. In this review, we will discuss recent advances in our understanding of intestinal macrophage heterogeneity, their ontogeny and the potential factors that regulate their origin. We will describe how the local environment of the intestine imprints the phenotypic and functional identity of the macrophage compartment, and how this changes during intestinal inflammation and infection. Finally, we highlight key outstanding questions that should be the focus of future research

Secure Session Framework: An Identity-based Cryptographic Key Agreement and Signature Protocol

Die vorliegende Dissertation beschäftigt sich mit der Methode der identitätsbasierten Verschlüsselung. Hierbei wird der Name oder die Identität eines Zielobjekts zum Verschlüsseln der Daten verwendet. Diese Eigenschaft macht diese Methode zu einem passenden Werkzeug für die moderne elektronische Kommunikation, da die dort verwendeten Identitäten oder Endpunktadressen weltweit eindeutig sein müssen. Das in der Arbeit entwickelte identitätsbasierte Schlüsseleinigungsprotokoll bietet Vorteile gegenüber existierenden Verfahren und eröffnet neue Möglichkeiten. Eines der Hauptmerkmale ist die komplette Unabhängigkeit der Schlüsselgeneratoren. Diese Unabhängigkeit ermöglicht es, dass verschiedene Sicherheitsdomänen ihr eigenes System aufsetzen können. Sie sind nicht mehr gezwungen, sich untereinander abzusprechen oder Geheimnisse auszutauschen. Auf Grund der Eigenschaften des Protokolls sind die Systeme trotzdem untereinander kompatibel. Dies bedeutet, dass Anwender einer Sicherheitsdomäne ohne weiteren Aufwand verschlüsselt mit Anwendern einer anderen Sicherheitsdomäne kommunizieren können. Die Unabhängigkeit wurde ebenfalls auf ein Signatur-Protokoll übertragen. Es ermöglicht, dass Benutzer verschiedener Sicherheitsdomänen ein Objekt signieren können, wobei auch der Vorgang des Signierens unabhängig sein kann. Neben dem Protokoll wurde in der Arbeit auch die Analyse von bestehenden Systemen durchgeführt. Es wurden Angriffe auf etablierte Protokolle und Vermutungen gefunden, die aufzeigen, ob oder in welchen Situationen diese nicht verwendet werden sollten. Dabei wurde zum einen eine komplett neue Herangehensweise gefunden, die auf der (Un-)Definiertheit von bestimmten Objekten in diskreten Räumen basiert. Zum anderen wurde die bekannte Analysemethode der Gitterreduktion benutzt und erfolgreich auf neue Bereiche übertragen. Schlussendlich werden in der Arbeit Anwendungsszenarien für das Protokoll vorgestellt, in denen dessen Vorteile besonders relevant sind. Das erste Szenario bezieht sich auf Telefonie, wobei die Telefonnummer einer Zielperson als Schlüssel verwendet. Sowohl GSM-Telefonie als auch VoIP-Telefonie werden in der Arbeit untersucht. Dafür wurden Implementierungen auf einem aktuellen Mobiltelefon durchgeführt und bestehende VoIP-Software erweitert. Das zweite Anwendungsbeispielsind IP-Netzwerke. Auch die Benutzung der IP-Adresse eines Rechners als Schlüssel ist ein gutes Beispiel, jedoch treten hier mehr Schwierigkeiten auf als bei der Telefonie. Es gibt beispielsweise dynamische IP-Adressen oder die Methode der textit{Network Address Translation}, bei der die IP-Adresse ersetzt wird. Diese und weitere Probleme wurden identifiziert und jeweils Lösungen erarbeitet

Stories that Change Our World? Narratives of the Sustainable Economy

Narratives are shaping our understanding of the world. They convey values and norms and point to desirable future developments. In this way, they justify and legitimize political actions and social practices. Once a narrative has emerged and this world view is supported by broad societal groups, narratives can provide powerful momentum to trigger innovation and changes in the course of action. Narratives, however, are not necessarily based on evidence and precise categories, but can instead be vague and ambiguous in order to be acceptable and attractive to different actors. However, the more open and inclusive a narrative is, the less impact can be expected. We investigate whether there is a shared narrative in research for the sustainable economy and how this can be evaluated in terms of its potential societal impact. The paper carves out the visions for the future that have been underlying the research projects conducted within the German Federal Ministry of Education and Research (BMBF) funding programme “The Sustainable Economy”. It then analyzes whether these visions are compatible with narratives dominating societal discourse on the sustainable economy, and concludes how the use of visions and narratives in research can contribute to fostering societal transformations

Different LFP frequency bands convey complementary information about the BOLD signal

Blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is the most widely used noninvasive imaging technique for investigating brain activity. However, the BOLD signal is only indirectly coupled to the underlying neural activity and the relationship between the two signals is not fully understood [1]. Recordings in anaesthetized and awake monkeys have shown that hemodynamic responses are strongly related to local field potentials (LFPs) [2,3]. LFPs are thought to represent the input and intracortical processing in a cortical area and are usually separated into different frequency bands that reflect different neural processes [4]. Previous studies have shown that different LFP bands correlate differently with the BOLD signal [3,5,6]. However little is known about which property of the BOLD signal is reflected by each band and whether different bands convey different information about the BOLD signal. To address this question we performed simultaneous recordings of neural activity and BOLD fMRI in early visual areas V1 and V2 in 4 anesthetized monkeys. All measurements were performed with the monkeys sitting in complete darkness while no stimulus was being presented. We computed mutual information between LFP power and BOLD fMRI to determine which frequencies in the LFPs were most informative about the BOLD signal. We found three highly informative bands, namely the alpha band [8-12Hz], the gamma band [40-100Hz] and the [18-35 Hz] “nMod” band that was previously found to be unrelated to visual stimuli and was thus suggested to primarily reflect neuromodulatory input [4]. We found that gamma power was the most informative about BOLD fMRI and reflected well changes in the amplitude of the BOLD signal. In particular, an increase in gamma power above its median value was followed, on average, by an increase in BOLD signal, and the BOLD signal decreased, instead, following a decrease in gamma power below its median. Moreover, we found that gamma and nMod power were complementary, i.e. that by combining nMod power together with gamma power we could extract 30 more information than could be extracted from gamma power alone. We investigated the origin of this complementarity and we found that the power in the nMod band reflected the timing with which changes in BOLD signal occurred following changes in gamma power. Finally, we found that, as suggested by previous theoretical work [7], an increase in alpha power without a change in total LFP power was followed by a decrease in BOLD signal and vice versa. These results indicate that distinct neural processes are reflected differently in the BOLD signal and that, consequently, it may be possible to retrieve information about the different contributions from the recorded BOLD time course

Expression and characterisation of αvβ5 integrin on intestinal macrophages

Macrophages play a crucial role in maintaining homeostasis in the intestine, but the underlying mechanisms have not yet been elucidated fully. Here we show for the first time that mature intestinal macrophages in mouse colon and small intestine express high levels of αvβ5 integrin, which acts as a receptor for the uptake of apoptotic cells and can activate molecules involved in several aspects of tissue homeostasis such as angiogenesis and remodelling of the extracellular matrix. αvβ5 is not expressed by other immune cells in the intestine, is already present on intestinal macrophages soon after birth, and its expression is not dependent on the microbiota. In adults, αvβ5 induces the differentiation of monocytes in response to the local environment and it confers intestinal macrophages with the ability to promote engulfment of apoptotic cells via engagement of the bridging molecule milk fat globule EGF‐like molecule 8. In the absence of αvβ5, there are fewer monocytes in the mucosa and mature intestinal macrophages have decreased expression of metalloproteases and interleukin 10. Mice lacking αvβ5 on haematopoietic cells show increased susceptibility to chemical colitis and we conclude that αvβ5 contributes to the tissue repair by regulating the homeostatic properties of intestinal macrophages

Supporting Engineering Processes Utilizing Service-Oriented Grid Technology

Speeding up knowledge-intensive core processes in engineering and increas-ing the quality of their results is becoming more and more decisive, since economic pressure from national and international competitors and customers is rising. In particular, these demands exceed the organizational and infrastructural capacities of small and medium-sized enterprises (SME) by far. Hence, combining complementary core competencies across organizational boundaries is crucial for an enterprise's continuing success. Efficient and economically reasonable support of knowledge-intensive core processes in virtual organisations is therefore a predominant requirement for future IT infrastructures. The paradigm shift to service-orientation in Grid middleware opens the possibility to provide such support along the product lifecycle by employing a flexible software development approach, namely to compose applications from standard components, promising easier development and modification of Grid applications. In this paper, a service-oriented Grid computing approach is presented which aims at supporting distributed business processes in industry (see section 2 for industrial scenarios) from top level modelling, workflow design and exe-cution to actual Grid service code (presented in section 3). Parts of this gap between processes and code can be bridged by semi-automatically generated Grid service code. Orchestration of these Grid services is also automated by using a Grid-enabled workflow engine (see section 3). The feasibility of the proposed approach is demonstrated by presenting an exemplary process chain from the casting industry (see full paper)

Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7T

Decreases in stimulus-dependent blood oxygenation level dependent (BOLD) signal and their underlying neurovascular origins have recently gained considerable interest. In this study a multi-echo, BOLD-corrected vascular space occupancy (VASO) functional magnetic resonance imaging (fMRI) technique was used to investigate neurovascular responses during stimuli that elicit positive and negative BOLD responses in human brain at 7 T. Stimulus-induced BOLD, cerebral blood volume (CBV), and cerebral blood flow (CBF) changes were measured and analyzed in ‘arterial’ and ‘venous’ blood compartments in macro- and microvasculature. We found that the overall interplay of mean CBV, CBF and BOLD responses is similar for tasks inducing positive and negative BOLD responses. Some aspects of the neurovascular coupling however, such as the temporal response, cortical depth dependence, and the weighting between ‘arterial’ and ‘venous’ contributions, are significantly different for the different task conditions. Namely, while for excitatory tasks the BOLD response peaks at the cortical surface, and the CBV change is similar in cortex and pial vasculature, inhibitory tasks are associated with a maximum negative BOLD response in deeper layers, with CBV showing strong constriction of surface arteries and a faster return to baseline. The different interplays of CBV, CBF and BOLD during excitatory and inhibitory responses suggests different underlying hemodynamic mechanisms