4,031 research outputs found
A structural analysis of the A5/1 state transition graph
We describe efficient algorithms to analyze the cycle structure of the graph
induced by the state transition function of the A5/1 stream cipher used in GSM
mobile phones and report on the results of the implementation. The analysis is
performed in five steps utilizing HPC clusters, GPGPU and external memory
computation. A great reduction of this huge state transition graph of 2^64
nodes is achieved by focusing on special nodes in the first step and removing
leaf nodes that can be detected with limited effort in the second step. This
step does not break the overall structure of the graph and keeps at least one
node on every cycle. In the third step the nodes of the reduced graph are
connected by weighted edges. Since the number of nodes is still huge an
efficient bitslice approach is presented that is implemented with NVIDIA's CUDA
framework and executed on several GPUs concurrently. An external memory
algorithm based on the STXXL library and its parallel pipelining feature
further reduces the graph in the fourth step. The result is a graph containing
only cycles that can be further analyzed in internal memory to count the number
and size of the cycles. This full analysis which previously would take months
can now be completed within a few days and allows to present structural results
for the full graph for the first time. The structure of the A5/1 graph deviates
notably from the theoretical results for random mappings.Comment: In Proceedings GRAPHITE 2012, arXiv:1210.611
Childhood intelligence predicts premature mortality : Results from a 40-year population-based longitudinal study
Acknowledgements This study was supported by a grant from the Luxembourg Fonds National de la Recherche (VIVRE FNR/06/09/18) and a PhD scholarship awarded to the first author by the Fonds National de la Recherche.Peer reviewedPostprin
Flow Equations and BRS Invariance for Yang-Mills Theories
Flow equations describe the evolution of the effective action in
the process of varying an infrared cutoff . The presence of the infrared
cutoff explicitly breaks gauge and hence BRS invariance. We derive modified
Slavnov-Taylor identities, which are valid for nonvanishing . They guarantee
the BRS invariance of for , and hence allow the study of
non-abelian gauge theories by integrating the flow equations. Within a
perturbative expansion of , we derive an equation for a dependent
mass term for the gauge fields implied by the modified Slavnov-Taylor
identities.Comment: 10 pages, HD-THEP-94-02 (References and example added; version to
appear in Phys. Lett. B
Wound degradomics - current status and future perspectives
Proteases are pivotal modulators of extracellular matrix components and bioactive proteins at all phases of cutaneous wound healing and thereby essentially contribute to the successful reestablishment of skin integrity upon injury. As a consequence, disturbance of proteolytic activity at the wound site is a major factor in the pathology of chronic wounds. A large body of data acquired in many years of research provide a good understanding of how individual proteases may influence the repair process. The next challenge will be to integrate these findings and to elucidate the complex interactions of proteolytic enzymes, their inhibitors and substrates on a system-wide level. Here, we present novel approaches that might help to achieve this ambitious goal in cutaneous wound healing researc
Short chronological analysis of the 2007-2009 eruptive cycle and its nested cones formation at Llaima volcano
The Llaima volcano (38°41âS / 71°43âČW) is one of the most active volcanoes of South America. In the present work we have combined direct field and sequential photography observation plus remote sensing of low cost, making possible to reconstruct its 2007-2009 eruptive cycle. Llaima volcano eruption began on January 1, 2008 at 18:11 local time, preceded by seismic and surface precursory activity. The onset of eruptive activity was followed by a second paroxysmal eruption occurred on April 2009, and the occurrence of Hawaiian, strombolian and phreatomagmatic reactivation pulses which edified a series of small nested scoriae and spatter cones inside the main crater of volcano. Their evolution was widely registered, defining with clarity two eruptive stages and nine eruptive phases. Several basaltic pahoehoe and AA lava flows descended from the main crater, producing glaciers melting and then lahars, which transported large-size blocks of ice and boulders. Also, pyroclastic flows and ash fall events where observed. This activity persisted until 2009 when finally ended. The record is very important to learn about Llaima eruptive behavior and could be used in population risk management
Ubiquitination and Ubiquitin-Like Modifications in Multiple Myeloma: Biology and Therapy
Multiple myeloma is a genetically heterogeneous plasma cell malignancy characterized by organ damage and a massive production of (in-)complete monoclonal antibodies. Coping with protein homeostasis and post-translational regulation is therefore essential for multiple myeloma cells to survive. Furthermore, post-translational modifications such as ubiquitination and SUMOylation play key roles in essential pathways in multiple myeloma, including NFÎșB signaling, epigenetic regulation, as well as DNA damage repair. Drugs modulating the ubiquitin-proteasome system, such as proteasome inhibitors and thalidomide analogs, are approved and highly effective drugs in multiple myeloma. In this review, we focus on ubiquitin and ubiquitin-like modifications in the biology and current developments of new treatments for multiple myeloma
Psychoanalytic and cognitive-behavior therapy of chronic depression : study protocol for a randomized controlled trial
Background: Despite limited effectiveness of short-term psychotherapy for chronic depression, there is a lack of trials of long-term psychotherapy. Our study is the first to determine the effectiveness of controlled long-term psychodynamic and cognitive-behavioral (CBT) treatments and to assess the effects of preferential vs. randomized assessment.
Methods/design: Patients are assigned to treatment according to their preference or randomized (if they have no clear preference). Up to 80 sessions of psychodynamic or psychoanalytically oriented treatments (PAT) or up to 60 sessions of CBT are offered during the first year in the study. After the first year, PAT can be continued according to the ânaturalisticâ usual method of treating such patients within the system of German health care (normally from 240 up to 300 sessions over two to three years). CBT therapists may extend their treatment up to 80 sessions, but focus mainly maintenance and relapse prevention. We plan to recruit a total of 240 patients (60 per arm). A total of 11 assessments are conducted throughout treatment and up to three years after initiation of treatment. The primary outcome measures are the Quick Inventory of Depressive Symptoms (QIDS, independent clinician rating) and the Beck Depression Inventory (BDI) after the first year.
Discussion: We combine a naturalistic approach with randomized controlled trials(RCTs)to investigate how effectively chronic depression can be treated on an outpatient basis by the two forms of treatment reimbursed in the German healthcare system and we will determine the effects of treatment preference vs. randomization
Crucial role of local peroxynitrite formation in neutrophil-induced endothelial cell activation
Introduction and methods: The reaction of superoxide anions and NO not only results in a decreased availability of NO, but also leads to the formation of peroxynitrite, the role of which in the cardiovascular system is still discussed controversially. In cultured human endothelial cells, we studied whether there is a significant interaction between endothelial NO and neutrophil-derived superoxide anions in terms of endothelial peroxynitrite formation. We particularly studied whether a significantly higher redox-stress can be found in those endothelial cells directly adjacent to an activated neutrophil. Results: A considerable part of the 2,7-dihydrodichlorofluoresceine signal in endothelial cells was due to oxidation by peroxynitrite. Providing superoxide radicals by enzymatic source or by the neutrophil respiratory burst increased the fluorescence, which was attenuated by blockade of endothelial NO-synthase, suggesting that peroxynitrite was formed from neutrophil- or extracellular enzyme-derived superoxide and endothelial NO. Considerably higher fluorescence intensity was observed in endothelial cells in direct neighborhood to a neutrophil. This was particularly pronounced in the presence of a NO-donor and was accompanied by a strong activation of NF-ÎșB and increased expression of E-selectin in these cells. Conclusion: Endothelial cells adjacent to neutrophils may have elevated levels of peroxynitrite that result in an increased expression of adhesion molecules. Such cells might represent a preferential site for adhesion and migration of additional neutrophils when simultaneously high concentrations of NO and neutrophil-derived superoxide are present
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