ein Beitrag zur Didaktik der Kryptologie

We report on experiments on the time of factorization of semiprimes (i.e., products of two primes) using the systems ''Sage'' and ''CrypTool''. With some exceptions the time grows exponentially with the length of the semiprimes - as expected. Using the quadratic sieve implemented in CrypTool 2, we could factorize the number RSA-100, a 100-decimal-digits semiprime, on our laptop in less than eight and a half hours

ein Beitrag zur Didaktik der Algebra und Kryptologie

Eines der zur Zeit schnellsten Verfahren zur Faktorisierung ganzer Zahlen ist das ``Quadratische Sieb'' (engl. ``quadratic sieve factorization method''), das 1981 von Carl Pomerance entwickelt wurde. Wir beschreiben im Folgenden die Basisversion des Quadratischen Siebs sowie die Variante des Quadratischen Siebs mit mehrfachen Polynomen, das sogenannte ``Multiple Polynomial Quadratic Sieve'' MPQS, das unabhängig von J. Davis und D. Holdridge bzw. P. Montgomery gefunden wurde. Bei der Darstellung der Verfahren orientieren wir uns an [Buchmann 2010], [Crandall & Pomerance 2005], [Esslinger et al. 2011], [Pomerance 1996], 'Quadratisches Sieb' in [Wikipedia de] und 'quadratic sieve' in [Wikipedia en]

Blickverhalten und Orientierung von Kraftfahrern auf Landstraßen

Die kürzer gewordenen Bremswege moderner Pkw erlauben ein schnelleres Anhalten im Gefahrenfall. Dadurch erscheint es möglich, zukünftig auch kürzere Haltesichtweiten im Straßenentwurf zu fordern. Es ist jedoch fraglich, ob ein verringertes Sichtweitenniveau eine ausreichende Fahrerorientierung gewährleisten kann. In drei umfangreichen Versuchsreihen wurde das Blick- und Fahrverhalten von Probanden bei Versuchsfahrten im realen Verkehr sowie im Fahrsimulator untersucht. Das Untersuchungsprogramm umfasste Fahrten mit Blickbewegungsmessung, die Bearbeitung von Nebenaufgaben sowie die Reaktion an plötzlich auftauchenden Hindernissen. Ausgewertet wurden der Verlauf von Beanspruchungsindikatoren, Zuwendungshäufigkeiten zu Nebenaufgaben sowie Parameter des Fahrverhaltens bei geringer werdenden Sichtweiten. Aus den Ergebnissen konnten verallgemeinerungsfähige Aussagen zum Verhalten von Fahrern bei unterschiedlichen Sichtweiten abgeleitet werden. Es wurden Sichtweitenbereiche definiert, in denen eine ansteigende Beanspruchung der Fahrer auf eine unzureichende Orientierung über den Streckenverlauf hinweist bzw. in denen plötzlich auftauchende Hindernisse nur noch unter Schwierigkeiten gemeistert werden können. Daraus wurde ein entwurfsklassenbezogenes Modell einer Orientierungssichtweite abgeleitet, das die Belange der Fahrerorientierung im Straßenentwurf würdigt. Die Ergebnisse wurden bei der Fortschreibung der Entwurfsrichtlinien für Straßen berücksichtigt

Regionalism Panel Discussion

Regionalism Panel Discussion Featuring: Mr. Jon Cooper, Mr. Ralph Schulz, and Mr. Michael Skipper. Moderated by Mayor Karl Dean. October 7, 201

Deployment of a Distributed Fiber Optic Sensing (DFOS) monitoring station in Munich within INSIDE project

Distributed Fiber Optic Sensing (DFOS) is an innovative sensing technique, which has recently gained interest in various fields of geophysics, in particular for near-surface measurements. With the purpose of passive seismic monitoring (in the framework of the INSIDE project, supported by the German Federal Ministry for Economic Affairs and Energy, BMWi) a DFOS measurement station has been installed in Buchenhain (Gemeinde Baierbrunn, Landkreis München). Next to the DFOS system, a Trillium Compact 120 s seismometer has also been deployed to allow further processing of the data as well as the comparison of the measurements produced by the different acquisitions technologies. DFOS involves the use of optoelectronic devices, referred to as the interrogators, which send laser pulses in an optical fiber acting as the sensor. The technique aims to observe the deformation of the fiber in time and space, thanks to the light backscattered along the fiber. Therefore, the sensing technique allows interrogating long profiles with a dense spatial sampling, which is uneasy to obtain from classic geophysical techniques. Depending on the application and using the appropriate interrogator, DFOS can lead to distributed acoustic sensing (DAS), temperature sensing (DTS) or strain sensing (DSS) with various spatial and temporal resolutions. For instance, DAS proved its relevance for seismic applications, but also for infrastructure monitoring, among others. The DFOS station at Buchenhain allows the combined measurement of DAS, DTS and DSS data. Two fiber optic cable with different characteristics are deployed both on the surface (along a 90-m long loop) and in a dedicated well (over 250 m), which allows recording seismic signals with different directivities at the same station. After describing the measuring station and the setup, we present the results of the first months of acquisitions, including the recording of various seismic signals with among others teleseismic and regional earthquakes, as well as a nearby Vertical Seismic Profiling campaign. The joint deployment of different measurement methods on the same site gives the opportunity to evaluate the advantages of innovative seismic monitoring methods compared to more conventional ones. It also allows to consider advanced processing approaches thanks to the joint use of different types of measurements

INSIDE: Investigating the impact of geothermal exploitation in the Munich area The induced seismicity perspective

Scientific research is carried out in the framework of the INSIDE project (supported by the German Federal Ministry for Economic Affairs and Energy, BMWi) to assess the impact of deep geothermal exploitation on induced seismicity in the Munich area (Germany, Molasse Basin). The project involves the research institute Karlsruhe Institute of Technology as well as two geothermal operators, Stadtwerke München (SWM) and Innovative Energie für Pullach (IEP). The research work focuses on three aspects: the monitoring, the modelling and the integration with operations. With respect to the monitoring, the deployment of a measurement network going beyond the standard for seismological and geodetic observations is considered. Therefore, an extensive and plural monitoring network was designed to monitor high (seismicity) and low (subsidence, uplift) frequency deformation processes of the subsurface. Several types of technologies as well as several types of deployment configurations are involved. Their relative performances are intended to be compared in order to contribute to the development of suitable strategies for deformation monitoring and their data processing. After presenting the aim and purpose of the project, we concentrate on the status of the seismic measurement network being implemented around the three geothermal sites of Baierbrunn, Pullach and Schäftlarnstrasse. In addition to “standard” monitoring stations installed in the area, we report on the deployment of various innovative technical solutions, among which a seismic mini-array and a monitoring borehole dedicated to Distributed Acoustic Sensing (DAS). We show how these stations complement the existing network in Munich and present their main characteristics, in particular the associated noise measurements. We additionally discuss the data-management system being developed to handle all these new data

Effects of endothelin on hemodynamics, prostaglandins, blood coagulation and renal function

Effects of endothelin on hemodynamics, prostaglandins, blood coagulation and renal function. The interaction of the endogenous vasoconstrictors endothelin (ET), angiotensin II (Ang II) and catecholamines with the kallikrein-kinin-, prostaglandin and renin-aldosterone systems in the pathogenesis of acute renal failure (ARF) is still to be defined. In 18 anesthesized pigs the influence of i.v. bolus applications of ET (2 µg/kg), Ang II (10 µg/kg) and norepinephrine (NE; 20 µg/kg) on hemodynamics, plasmatic coagulation and fibrinolysis system, prostaglandins and renal function was studied. ET induced a biphasic change in blood pressure, starting with an initial short-lasting reduction followed by a long-lasting elevation of systolic and diastolic blood pressure. Endothelin bolus resulted in a significant increase of 6-keto-PGF1α, PGE2 and TXB2 plasma levels (P < 0.05 against preinjection values), whereas prostaglandins remained unchanged in the Ang II and NE groups. There was a distinct correlation between the plasma ET and 6-keto-PGF1α levels (r = 0.82). In contrast to Ang II or NE, ET induced a shortening of the activated partial thromboplastin time (aPTT) and increase of antithrombin III levels (ATIII), fibrin monomers (FM), prekallikrein (PKK) and factor VIII activity at the beginning. Finally a pronounced decrease of ATIII, FM and PKK occurred, indicating a consumptive coagulopathy. At the end of the experiment, elevated plasma renin activity and pCO2, significantly decreased creatinine clearance, blood pH, pO2, base excess, HCO3-, oxygen saturation (P < 0.01), a distinct glomerular proteinuria, and a final anuria were observated. These results reveal that ET activates the plasmatic coagulation system and induces an ARF accompanied by impairment of pulmonary function. Its coagulation activating and renal vasoconstrictive effects may be important pathophysiological factors, especially when the counteractive release of vasodilatator and antiaggregatory prostacyclin or NO is impaired

Audience effects in the Atlantic molly (Poecilia mexicana)–prudent male mate choice in response to perceived sperm competition risk?

Background Multidirectional interactions in social (or communication) networks can have a profound effect on mate choice behavior. For example, Poecilia mexicana males show weaker expression of mating preferences when being observed by an audience male. It was suggested that this behavior is an adaptation to reduce sperm competition risk, which arises because commonly preferred female phenotypes will receive attention also by surrounding males, and/or because the audience male can copy the focal male's mate choice. Do P. mexicana males indeed respond to perceived sperm competition risk? We gave males a choice between two females and repeated the tests under one of the following conditions: (1) during the 2nd part of the tests an empty transparent cylinder was presented (control); (2) an audience male inside the cylinder observed the focal male throughout the 2nd part, or (3) the audience male was presented only before the tests, but could not eavesdrop during the actual choice tests (non-specific sperm competition risk treatments); (4) the focal male could see a rival male sexually interacting with the previously preferred, or (5) with the non-preferred female before the 2nd part of the tests (specific sperm competition risk treatments). Results When comparing the strength of individual male preferences between the 1st and 2nd part of the tests (before and after presentation of an audience), male preferences declined slightly also during the control treatment (1). However, the decrease in strength of male preferences was more than two-fold stronger in audience treatment (2), i.e., with non-specific sperm competition risk including the possibility for visual eavesdropping by the audience male. No audience effect was found in treatments (3) and (5), but a weak effect was also seen when the focal male had seen the previously preferred female sexually interact with a rival male (treatment 4; specific sperm competition risk). Conclusions When comparing the two 'non-specific sperm competition risk' treatments (2 and 3), a very strong effect was found only when the audience male could actually observe the focal male during mate choice in treatment (2). This suggests that focal males indeed attempt to conceal their mating preferences in the visual presence of other males so as to avoid mate choice copying. When there is no potential for eavesdropping [treatment (3)], non-specific specific sperm competition risk seems to play a minor or no role. Congruent with studies on other poeciliid species, our results also show that P. mexicana males respond to perceived specific sperm competition risk, and tend to share their mating effort more equally among females when the resource value of their previously preferred mate decreases (after mating with a rival male). However, this effect is comparatively weak