On the security of the Mobile IP protocol family

The Internet Engineering Task Force (IETF) has worked on\ud network layer mobility for more than 10 years and a number\ud of RFCs are available by now. Although the IETF mobility\ud protocols are not present in the Internet infrastructure as of\ud today, deployment seems to be imminent since a number\ud of organizations, including 3GPP, 3GPP2 and Wimax, have\ud realized the need to incorporate these protocols into their architectures.\ud Deployment scenarios reach from mobility support\ud within the network of a single provider to mobility support\ud between different providers and technologies. Current Wimax\ud specifications, for example, already support Mobile IPv4,\ud Proxy Mobile IPv4 and Mobile IPv6. Future specifications will\ud also support Proxy Mobile IPv6. Upcoming specifications in\ud the 3GPP Evolved Packet Core (EPC) will include the use of\ud Mobile IPv4, Dual Stack MIPv6 and Proxy Mobile IPv6 for\ud interworking between 3GPP and non 3GPP networks.\ud This paper provides an overview on the state-of-the-art\ud in IETF mobility protocols as they are being considered by\ud standardization organizations outside the IETF and focusing\ud on security aspects

Boundary drive induced formation of aggregate condensates in stochastic transport with short-range interactions

We discuss the effects of particle exchange through open boundaries and the induced drive on the phase structure and condensation phenomena of a stochastic transport process with tunable short-range interactions featuring pair-factorized steady states (PFSS) in the closed system. In this model, the steady state of the particle hopping process can be tuned to yield properties from the zero-range process (ZRP) condensation model to those of models with spa- tially extended condensates. By varying the particle exchange rates as well as the presence of a global drift, we observe a phase transition from a free particle gas to a phase with condensates aggregated to the boundaries. While this transition is similar to previous results for the ZRP, we find that the mechanism is different as the presence of the boundary actually influences the interaction due to the non-zero interaction range.Comment: 6 pages, 7 figure

Merging Electrosynthesis with 3d Transition Metal-Catalyzed C–H Transformations

In recent years, oxidative C–H transformations have emerged as increasingly powerful tools in molecular syntheses. However, despite great progress towards more atom and step economic synthetic methods, oxidative couplings largely rely on precious metal catalysts and stoichiometric amounts of toxic metal oxidants, which compromises the overall sustainability of the C–H activation strategy. Within this thesis, this contradiction was resolved by the direct merger of electrochemistry with 3d metal-catalyzed C–H activation, thus setting the stage for organic syntheses at a unique level of resource economy. The novel metallaelectrocatalysis was employed for the traceless formation of various C–C or C–Het bonds. In addition, the mechanisms of these reactions were investigated by detailed mechanistic studies, uncovering, among others, novel mechanistic scenarios to be effective within cobaltaelectrocatalysis.2021-07-1

Open boundary conditions in stochastic transport processes with pair-factorized steady states

Using numerical methods we discuss the effects of open boundary conditions on condensation phenomena in the zero-range process (ZRP) and transport processes with pair-factorized steady states (PFSS), an extended model of the ZRP with nearest-neighbor interaction. For the zero-range process we compare to analytical results in the literature with respect to criticality and condensation. For the extended model we find a similar phase structure, but observe supercritical phases with droplet formation for strong boundary drives.Comment: conference contribution for the 27th Annual CSP Workshop on "Recent Developments in Computer Simulation Studies in Condensed Matter Physics", CSP 2014 5 pages, 5 figure

Coarse-Grained Modeling of Genetic Circuits as a Function of the Inherent Time Scales

From a coarse-grained perspective the motif of a self-activating species, activating a second species which acts as its own repressor, is widely found in biological systems, in particular in genetic systems with inherent oscillatory behavior. Here we consider a specific realization of this motif as a genetic circuit, in which genes are described as directly producing proteins, leaving out the intermediate step of mRNA production. We focus on the effect that inherent time scales on the underlying fine-grained scale can have on the bifurcation patterns on a coarser scale in time. Time scales are set by the binding and unbinding rates of the transcription factors to the promoter regions of the genes. Depending on the ratio of these rates to the decay times of the proteins, the appropriate averaging procedure for obtaining a coarse-grained description changes and leads to sets of deterministic equations, which differ in their bifurcation structure. In particular the desired intermediate range of regular limit cycles fades away when the binding rates of genes are of the same order or less than the decay time of at least one of the proteins. Our analysis illustrates that the common topology of the widely found motif alone does not necessarily imply universal features in the dynamics.Comment: 29 pages, 16 figure

Public awareness and use of German physician ratings sites: Cross-sectional survey of four north German cities

Background: Physician rating websites (PRWs) allow patients to rate, comment, and discuss physicians’ quality. The ability of PRWs to influence patient decision making and health care quality is dependent, in part, on sufficient awareness and usage of PRWs. However, previous studies have found relatively low levels of awareness and usage of PRWs, which has raised concerns about the representativeness and validity of information on PRWs. Objective: The objectives of this study were to examine (1) participants’ awareness, use, and contribution of ratings on PRWs and how this compares with other rating websites; (2) factors that predict awareness, use, and contribution of ratings on PRWs; and (3) participants’ attitudes toward PRWs in relation to selecting a physician. Methods: A mailed cross-sectional survey was sent to a random sample (N=1542) from four North German cities (Nordhorn, Hildesheim, Bremen, and Hambur g) between April and July 2016. Survey questions explored respondents’ awareness, use, and contribution of ratings on rating websites for service (physicians, hospitals, and hotels and restaurants) and products (media and technical) in general and the role of PRWs when searching for a new physician. Results: A total of 280 completed surveys were returned (280/1542, 18.16% response rate), with the following findings: (1) Overall, 72.5% (200/276) of respondents were aware of PRWs. Of the respondents who were aware of PRWs, 43.6% (86/197) had used PRWs. Of the respondents who had used PRWs, 23% (19/83) had rated physicians at least once. Awareness, use, and contribution of ratings on PRWs were significantly lower in comparison with all other rating websites, except for hospital rating websites. (2) Except for the impact of responders’ gender and marital status on the awareness of PRWs and responders’ age on the use of PRWs, no other predictors had a relevant impact. (3) Whereas 31.8% (85/267) of the respondents reported that PRWs were a very important or somewhat important information source when searching for a new physician, respondents significantly more often reported that family , friends and colleagues (259/277, 93.5%), other physicians (219/274, 79.9%), and practice websites (108/266, 40.6%) were important information sources. Conclusions: Whereas awareness of German PRWs appears to have substantially increased, the use of PRWs and contribution of ratings remains relatively low. Further research is needed to examine the reasons why only a few patients are rating physicians. However, given the information inequality between provider and consumer will always be higher for consumers using the services of physicians, it is possible that people will always rely more on interpersonal recommendations than impersonal public information before selecting a physician

Sparzwang und Kriminalitätsrisiko: Gibt es Zusammenhänge? : Offene Fragen, und erste Ergebnisse aus einem Forschungsprojekt

Der nachhaltige Sparzwang in Zeiten leerer öffentlicher Kassen wird auch zu Einbußen im Bereich der Kriminalprävention führen, insbesondere im Bereich der Jugend- und der Jugendgerichtshilfe. Die Folgen könnten einen deutlichen Anstieg der Kriminalität bedeuten. Wie dieser Artikel jedoch aufzeigt, sind quantifizierbare Zusammenhänge zwischen (finanziellen und personellen) Inputs und Erfolgen der Kriminalpolitik unklar. Die Gründe hierfür sind mannigfaltig. Ein Defizit besteht in den fehlenden Schätzungen der Kosten in Kriminalität, ferner nimmt Deutschland im Vergleich zu anderen Industrieländern an den regelmäßig durchgeführten internationalen Opferstudien nicht teil. Weitere Mängel bestehen in der für eine Erfolgskontrolle unzureichenden Nutzbarkeit bestehender Rückfallstatistiken sowie in der fehlenden oder mangelhaften Durchführung der Evaluation angebotener Maßnahmen. Der vorliegende Artikel weist auf die Gründe für diese Informationsdefizite hin und zeigt anhand von ersten Forschungsergebnissen des an der TU Darmstadt durchgeführten Forschungsprojektes "Kosten und Nutzen von Haft und Haftvermeidung", welche Erkenntnisse potentiell weiterhelfen könnten

Stateful Testing: Finding More Errors in Code and Contracts

Automated random testing has shown to be an effective approach to finding faults but still faces a major unsolved issue: how to generate test inputs diverse enough to find many faults and find them quickly. Stateful testing, the automated testing technique introduced in this article, generates new test cases that improve an existing test suite. The generated test cases are designed to violate the dynamically inferred contracts (invariants) characterizing the existing test suite. As a consequence, they are in a good position to detect new errors, and also to improve the accuracy of the inferred contracts by discovering those that are unsound. Experiments on 13 data structure classes totalling over 28,000 lines of code demonstrate the effectiveness of stateful testing in improving over the results of long sessions of random testing: stateful testing found 68.4% new errors and improved the accuracy of automatically inferred contracts to over 99%, with just a 7% time overhead.Comment: 11 pages, 3 figure

Echtzeitoptimierung für Ausweichtrajektorien : mittels der Sensitivitätsanalyse eines parametergestörten nichtlinearen Optimierungsproblems

In this thesis an approach for the real-time computation of trajectories and controls for collision avoidance in cars traffic is presented. The approach handles the full complexity of a nonlinear model of the host car's dynamics and keeps it stable during the maneuver. A switching point optimization technique reduces the number of variables and constraints in the desired nonlinear optimization problem drastically. Via parametric sensitivity analysis of perturbed nonlinear optimization problems an approach for real-time computation of near-optimal trajectories is developed. This approach leads to the possibility of a rather simple implementation in a car but is still generic enough to cover numerous different collision scenarios. Examples from collision avoidance demonstrate the capabilities of the desired method