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Quantum cryptography

Dagmar Bruss, Gábor Erdélyi, Tim Meyer, Tobias Riege, Jörg Rothe
2007 ACM Computing Surveys  
Riege, and J. Rothe, Institut für Informatik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany; email: {erdelyi,riege,rothe}@cs.uni-duesseldorf.de.  ... 
doi:10.1145/1242471.1242474 fatcat:evyehi34xjhdtcecipbg5usbi4

An Exact 2.9416^n Algorithm for the Three Domatic Number Problem [article]

Tobias Riege, Jörg Rothe
2005 arXiv   pre-print
The three domatic number problem asks whether a given undirected graph can be partitioned into at least three dominating sets, i.e., sets whose closed neighborhood equals the vertex set of the graph. Since this problem is NP-complete, no polynomial-time algorithm is known for it. The naive deterministic algorithm for this problem runs in time 3^n, up to polynomial factors. In this paper, we design an exact deterministic algorithm for this problem running in time 2.9416^n. Thus, our algorithm
more » ... handle problem instances of larger size than the naive algorithm in the same amount of time. We also present another deterministic and a randomized algorithm for this problem that both have an even better performance for graphs with small maximum degree.
arXiv:cs/0506090v1 fatcat:ssopzsvkdrhllfxyz7s6syfugu

Optimized One-Click Development for Topology-Optimized Structures

Tobias Rosnitschek, Rick Hentschel, Tobias Siegel, Claudia Kleinschrodt, Markus Zimmermann, Bettina Alber-Laukant, Frank Rieg
2021 Applied Sciences  
Topology optimization is a powerful digital engineering tool for the development of lightweight products. Nevertheless, the transition of obtained design proposals into manufacturable parts is still a challenging task. In this article, the development of a freeware framework is shown, which uses a hybrid topology optimization algorithm for stiffness and strength combined with manufacturing constraints based on finite spheres and a two-step smoothing algorithm to design manufacturable prototypes
more » ... with "one click". The presented workflow is shown in detail on a rocker, which is "one-click"-optimized and manufactured. These parts were experimentally tested using a universal testing machine. The objective of this article was to investigate the performance of "one-click"-optimized parts in comparison with manually redesigned optimized parts and the initial design space. The test results show that the design proposals created while applying the finite-spheres and two-step smoothing are equal to the manual redesigned parts based on the optimization results, proposing that the "one-click"-development can be used for the fast and direct development and fabrication of prototypes.
doi:10.3390/app11052400 fatcat:ro72dm2bgffwtnxko7p3mqj4mi

An Improved Exact Algorithm for the Domatic Number Problem [article]

Tobias Riege, Jörg Rothe, Holger Spakowski, Masaki Yamamoto
2006 arXiv   pre-print
addition, we show that the 3-domatic number problem can be solved for graphs G with bounded maximum degree Delta(G) by a randomized algorithm, whose running time is better than the previous bound due to Riege  ...  Riege and Rothe [RR05] described a randomized algorithm for this problem.  ...  The first algorithm beating the trivialÕ(3 n ) barrier 1 for the 3-domatic number problem is due to Riege and Rothe [RR05] .  ... 
arXiv:cs/0603060v1 fatcat:tthcokzv7fe53h4gwwasry3jky

An Automated Open-Source Approach for Debinding Simulation in Metal Extrusion Additive Manufacturing

Tobias Rosnitschek, Johannes Glamsch, Christopher Lange, Bettina Alber-Laukant, Frank Rieg
2021 Designs  
As an alternative to powder-bed based processes, metal parts can be additively manufactured by extrusion based additive manufacturing. In this process, a highly filled polymer filament is deposited and subsequently debindered and sintered. Choosing a proper orientation of the part that satisfies the requirements of the debinding and sintering processes is crucial for a successful manufacturing process. To determine the optimal orientation for debinding, first, the part must be scaled in order
more » ... compensate the sinter induced shrinkage. Then, a finite element analysis is performed to verify that the maximum stresses due to the dead load do not exceed the critical stress limits. To ease this selection process, an approach based on open source software is shown in this article to efficiently determine a part's optimal orientation during debinding. This automates scaling, debinding simulation, and postprocessing for all six main directions. The presented automated simulation framework is examined on three application examples and provides plausible results in a technical context for all example parts, leading to more robust part designs and a reduction of experimental trial and error. Therefore, the presented framework is a useful tool in the product development process for metal extrusion additive manufacturing applications.
doi:10.3390/designs5010002 fatcat:p2d3th4phrc6dhvh62f2n7rnga

Combining Structural Optimization and Process Assurance in Implicit Modelling for Casting Parts

Tobias Rosnitschek, Maximilian Erber, Christoph Hartmann, Wolfram Volk, Frank Rieg, Stephan Tremmel
2021 Materials  
The structural optimization of manufacturable casting parts is still a challenging and time-consuming task. Today, topology optimization is followed by a manual reconstruction of the design proposal and a process assurance simulation to endorse the design proposal. Consequently, this process is iteratively repeated until it reaches a satisfying compromise. This article shows a method to combine structural optimization and process assurance results to generate automatically structure- and
more » ... -optimized die casting parts using implicit geometry modeling. Therefore, evaluation criteria are developed to evaluate the current design proposal and qualitatively measure the improvement of manufacturability between two iterations. For testing the proposed method, we use a cantilever beam as an example of proof. The combined iterative method is compared to manual designed parts and a direct optimization approach and evaluated for mechanical performance and manufacturability. The combination of topology optimization (TO) and process assurance (PA) results is automated and shows a significant enhancement to the manual reconstruction of the design proposals. Further, the improvement of manufacturability is better or equivalent to previous work in the field while using less computational effort, which emphasizes the need for suitable metamodels to significantly reduce the effort for process assurance and enable much shorter iteration times.
doi:10.3390/ma14133715 pmid:34279285 pmcid:PMC8269844 fatcat:5wnb2ceq4jdrddhb6ffvuny54a

Impact of HPC and Automated CFD Simulation Processes on Virtual Product Development—A Case Study

Christopher Lange, Patrick Barthelmäs, Tobias Rosnitschek, Stephan Tremmel, Frank Rieg
2021 Applied Sciences  
High-performance computing (HPC) enables both academia and industry to accelerate simulation-driven product development processes by providing a massively parallel computing infrastructure. In particular, the automation of high-fidelity computational fluid dynamics (CFD) analyses aided by HPC systems can be beneficial since computing time decreases while the number of significant design iterations increases. However, no studies have quantified these effects from a product development point of
more » ... ew yet. This article evaluates the impact of HPC and automation on product development by studying a formula student racing team as a representative example of a small or medium-sized company. Over several seasons, we accompanied the team, and provided HPC infrastructure and methods to automate their CFD simulation processes. By comparing the team's key performance indicators (KPIs) before and after the HPC implementation, we were able to quantify a significant increase in development efficiency in both qualitative and quantitative aspects. The major aerodynamic KPI increased up to 115%. Simultaneously, the number of expedient design iterations within one season increased by 600% while utilizing HPC. These results prove the substantial benefits of HPC and automation of numerical-intensive simulation processes for product development.
doi:10.3390/app11146552 fatcat:2ejg53iwrvhclmt5claruaus6m

Complexity of the Exact Domatic Number Problem and of the Exact Conveyor Flow Shop Problem

Tobias Riege, Jörg Rothe
2004 Theory of Computing Systems  
Lemma 30 (Espelage and Riege) .  ... 
doi:10.1007/s00224-004-1209-8 fatcat:4pnuvyom3jcnpk3xi5skju52v4

Extracorporeal membrane oxygenation in Pneumocystis jirovecii pneumonia: outcome in HIV and non-HIV patients

Jonathan Rilinger, Dawid L. Staudacher, Siegbert Rieg, Daniel Duerschmied, Christoph Bode, Tobias Wengenmayer
2019 Critical Care  
doi:10.1186/s13054-019-2661-9 pmid:31727133 pmcid:PMC6854795 fatcat:qtaostdesnaojmijrsi5cfrota

Complexity of the Exact Domatic Number Problem and of the Exact Conveyor Flow Shop Problem [article]

Tobias Riege, Jörg Rothe
2004 arXiv   pre-print
Lemma 30 (Espelage and Riege) There exists a polynomial-time many-one reduction g that witnesses 3-SAT ≤ p m CFSP and satisfies, for each given boolean formula ϕ, the following properties: 1. g(ϕ) = M  ... 
arXiv:cs/0212016v3 fatcat:q74fzbdvz5hj7mlmgbrd25eo4q

Influence of immunosuppression in patients with severe acute respiratory distress syndrome on veno‐venous extracorporeal membrane oxygenation therapy

Jonathan Rilinger, Viviane Zotzmann, Xavier Bemtgen, Siegbert Rieg, Paul M Biever, Daniel Duerschmied, Torben Pottgiesser, Klaus Kaier, Christoph Bode, Dawid L Staudacher, Tobias Wengenmayer
2021 Artificial Organs  
Prognosis of patients suffering of acute respiratory distress syndrome (ARDS) is poor. This is especially true for immunosuppressed patients. If these patients should receive veno-venous extracorporeal membrane oxygenation (VV ECMO) is discussed controversial while evidence on this topic is sparse. We report retrospective data of a single-centre registry of patients with severe ARDS requiring ECMO support between 10/2010 and 06/2019. Patients were analysed by their status of immunosuppression.
more » ... CMO weaning success and hospital survival were analysed before and after propensity score matching (PSM). Moreover, ventilator free days (VFD) were compared. A total of 288 patients were analysed (age 55years, 67%male), 88 (31%) presented with immunosuppression. Survival rates were lower in immunosuppressed patients (27%vs.53%, p<0.001 and 27%vs.48% after PSM, p=0.006). VFD (60 days) were lower for patients with immunosuppression (11.9vs.22.4, p<0.001) and immunosuppression was an independent predictor for mortality in multivariate analysis. Hospital survival was 20%, 14%, 35% and 46% for patients with oncological malignancies, solid organ transplantation, autoimmune diseases and HIV, respectively. In this analysis immunosuppression was an independent predictor for mortality. However, there were major differences in the weaning and survival rates between the aetiologies of immunosuppression which should be considered in decision making.
doi:10.1111/aor.13954 pmid:33725377 pmcid:PMC8250998 fatcat:arauvu2qljfi5dhqib4urteswe

Neuropsychological profiles and cerebral glucose metabolism in neurocognitive Long COVID-syndrome

Andrea Dressing, Tobias Bormann, Ganna Blazhenets, Nils Schroeter, Lea I Walter, Johannes Thurow, Dietrich August, Hanna Hilger, Katarina Stete, Kathrin Gerstacker, Susan Arndt, Alexander Rau (+6 others)
2021 Journal of Nuclear Medicine  
During the Corona Virus Disease 2019 (COVID-19) pandemic, Long COVID-syndrome, which impairs patients through cognitive deficits, fatigue, and exhaustion, has become increasingly relevant. Its underlying pathophysiology, however, is unknown. In this study, we assessed cognitive profiles and regional cerebral glucose metabolism as a biomarker of neuronal function in outpatients suffering from long-term neurocognitive symptoms after COVID-19. Methods: Outpatients seeking neurological counseling
more » ... th neurocognitive symptoms persisting for more than three months after polymerase chain reaction (PCR)-confirmed COVID-19 were included prospectively between June 16, 2020, and January 29, 2021. Patients (n = 31, 54±2.0 years) in the long-term phase after COVID-19 (202±58 days after positive PCR) were assessed with a neuropsychological test battery. Cerebral 18F-FDG PET imaging was performed in 14/31 patients. Results: Patients self-reported impaired attention, memory, and multitasking abilities (31/31), word-finding difficulties (27/31), and fatigue (24/31). Twelve of 31 patients could not return to the previous level of independence/employment. For all cognitive domains, average group results of the neuropsychological test-battery showed no impairment, but deficits (z-score<-1.5) were present on single-patient level mainly in the domain of visual memory (in 7/31; other domains ≤2/31). Mean MoCA performance (27/30 points) was above the cutoff-value for detection of cognitive impairment (< 26 points), although 9/31 patients performed slightly below this level (23-25 points). In the subgroup of patients who underwent 18F-FDG PET, we found no significant changes of regional cerebral glucose metabolism. Conclusion: Long COVID patients self-report uniform symptoms hampering their ability to work in a relevant fraction. However, cognitive testing showed minor impairments only on single-patient level approximately six months after the infection, whereas functional imaging revealed no distinct pathological changes. This clearly deviates from previous findings in subacute COVID-19 patients, suggesting that underlying neuronal causes are different and possibly related to the high prevalence of fatigue.
doi:10.2967/jnumed.121.262677 pmid:34649946 pmcid:PMC9258569 fatcat:a3rz2duizvgs3g3vwk3brk4e5y

High-resolution ab initio three-dimensional x-ray diffraction microscopy

Henry N. Chapman, Anton Barty, Stefano Marchesini, Aleksandr Noy, Stefan P. Hau-Riege, Congwu Cui, Malcolm R. Howells, Rachel Rosen, Haifeng He, John C. H. Spence, Uwe Weierstall, Tobias Beetz (+2 others)
2006 Optical Society of America. Journal A: Optics, Image Science, and Vision  
Coherent X-ray diffraction microscopy is a method of imaging non-periodic isolated objects at resolutions only limited, in principle, by the largest scattering angles recorded. We demonstrate X-ray diffraction imaging with high resolution in all three dimensions, as determined by a quantitative analysis of the reconstructed volume images. These images are retrieved from the 3D diffraction data using no a priori knowledge about the shape or composition of the object, which has never before been
more » ... emonstrated on a non-periodic object. We also construct 2D images of thick objects with infinite depth of focus (without loss of transverse spatial resolution). These methods can be used to image biological and materials science samples at high resolution using X-ray undulator radiation, and establishes the techniques to be used in atomic-resolution ultrafast imaging at X-ray free-electron laser sources.
doi:10.1364/josaa.23.001179 pmid:16642197 fatcat:6nuviza4kjhf7lsuwcmep34ib4

Profiling structured beams using injected aerosols

N. D. Loh, Dmitri Starodub, Lukas Lomb, Christina Y. Hampton, Andrew V. Martin, Raymond G. Sierra, Anton Barty, Andrew Aquila, Joachim Schulz, Jan Steinbrener, Robert L. Shoeman, Stephan Kassemeyer (+48 others)
2012 X-Ray Free-Electron Lasers: Beam Diagnostics, Beamline Instrumentation, and Applications  
Profiling structured beams produced by X-ray free-electron lasers (FELs) is crucial to both maximizing signal intensity for weakly scattering targets and interpreting their scattering patterns. Earlier ablative imprint studies describe how to infer the X-ray beam profile from the damage that an attenuated beam inflicts on a substrate. However, the beams in-situ profile is not directly accessible with imprint studies because the damage profile could be different from the actual beam profile. On
more » ... he other hand, although a Shack-Hartmann sensor is capable of in-situ profiling, its lenses may be quickly damaged at the intense focus of hard X-ray FEL beams. We describe a new approach that probes the in-situ morphology of the intense FEL focus. By studying the translations in diffraction patterns from an ensemble of randomly injected sub-micron latex spheres, we were able to determine the non-Gaussian nature of the intense FEL beam at the Linac Coherent Light Source (SLAC Downloaded From: http://proceedings.spiedigitallibrary.org/ on 12/05/2016 Terms of Use: http://spiedigitallibrary.org/ss/termsofuse.aspx National Laboratory) near the FEL focus. We discuss an experimental application of such a beam-profiling technique, and the limitations we need to overcome before it can be widely applied. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 12/05/2016 Terms of Use: http://spiedigitallibrary.org/ss/termsofuse.aspx Proc. of SPIE Vol. 8504 850403-4 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 12/05/2016 Terms of Use: http://spiedigitallibrary.org/ss/termsofuse.aspx Proc. of SPIE Vol. 8504 850403-6 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 12/05/2016 Terms of Use: http://spiedigitallibrary.org/ss/termsofuse.aspx
doi:10.1117/12.930075 fatcat:7wfyervn2vh23fhdcwxiihjvni

Characterization of pre-existing and induced SARS-CoV-2-specific CD8+ T cells

Isabel Schulien, Janine Kemming, Valerie Oberhardt, Katharina Wild, Lea M. Seidel, Saskia Killmer, Sagar, Franziska Daul, Marilyn Salvat Lago, Annegrit Decker, Hendrik Luxenburger, Benedikt Binder (+20 others)
2020 Nature Medicine  
These authors jointly supervised this work: Tobias Boettler, Bertram Bengsch, Robert Thimme, Maike Hofmann, Christoph Neumann-Haefelin. ✉ e-mail: robert.thimme@uniklinik-freiburg.de; maike.hofmann@uniklinik-freiburg.de  ... 
doi:10.1038/s41591-020-01143-2 pmid:33184509 fatcat:4vfqecemwraufnrexmgq4ltoeu
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