Vertrauensbasierte Laufzeitüberwachung verteilter komponentenstrukturierter E-Commerce-Software

Die Entwicklung komponentenstrukturierter E-Commerce-Software ist kostengünstig und schnell, da man die Systeme recht einfach aus wiederverwendbaren Softwarekomponenten zusammensetzt. Allerdings führt diese Entwurfsmethode zu einer neuen Art an Problemen für die Datensicherheit dieser Systeme. Insbesondere besteht die Gefahr, dass eine bösartige Komponente die gesamte Anwendung, in die sie eingebunden ist, bedroht. Zur Abwehr dieser Gefahr verwenden wir Security Wrapper, die das Verhalten von Komponenten zur Laufzeit überwachen und die Sicherheitsanforderungen der Anwendung durchsetzen. Ein Security Wrapper beobachtet das Verhalten an der Schnittstelle einer Komponenten und vergleicht es mit den vom Komponentenentwickler garantierten Sicherheitspolicies, die in der Komponentenspezifikation formal beschrieben werden. Wir stellen vor, wie man die Sicherheitspolicies zustandsbasiert beschreibt und führen eine Sammlung an Spezifikationsmustern ein, aus denen man die Modelle der Sicherheitspolicies für eine Komponente ableitet. Schließlich zeigen wir den Einsatz der Security Wrapper anhand eines E-Procurement- Beispiels. Darüberhinaus erläutern wir, wie man unter Berücksichtigung der Erfahrungen anderer Nutzer mit einer Komponente den Aufwand der Laufzeittests reduzieren kann. Dazu verwenden wir einen speziellen Vertrauensmanagement-Service, der gute und schlechte Erfahrungen unterschiedlicher Benutzer mit Komponenten verwaltet. Abhängig von diesen Erfahrungsberichten können die Security Wrapper das Ausmaß der Überwachung absenken, indem sie anstatt einer vollständigen Überwachung nur Stichproben durchführen oder die Überwachung sogar abbrechen

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon-neutrinos, as predicted from, e.g., the sum of all active galaxies in the universe. This search yielded no excess events above those expected from the background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux. For an assumed E^-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E^2 Phi(E) = 8.4 x 10^-7 GeV cm^-2 s^-1 sr^-1 (for a predominant neutrino energy range 6-1000 TeV) which is the most restrictive bound placed by any neutrino detector. When specific predicted spectral forms are considered, it is found that some are excluded.Comment: Submitted to Physical Review Letter

An upper limit to the photon fraction in cosmic rays above 10^19 eV from the Pierre Auger Observatory

An upper limit of 16% (at 95% c.l.) is derived for the photon fraction in cosmic rays with energies above 10^19 eV, based on observations of the depth of shower maximum performed with the hybrid detector of the Pierre Auger Observatory. This is the first such limit on photons obtained by observing the fluorescence light profile of air showers. This upper limit confirms and improves on previous results from the Haverah Park and AGASA surface arrays. Additional data recorded with the Auger surface detectors for a subset of the event sample, support the conclusion that a photon origin of the observed events is not favoured

Предварительное исследование применения системы спектрального регулирования для ТВС реактора ВВЭР-1000

Повышение топливных характеристик ядерных реакторов за счет применения концепции управления спектральным сдвигом (SSC) вместо традиционных методов, основанных на поглощении, является многообещающим подходом к снижению стоимости топливного цикла и увеличению использования топливных ресурсов (U, Pu). В данной работе было проведено исследование применения химического метода SSC для модели топливной сборки ВВЭР-1000 с низкообогащенным ураном, в которой контроль реактивности осуществляется путем изменения доли D2O относительно легководного замедлителя (D2O/H2O), и сравнение с поглощающими материалами, в которых содержится 600 ppm H3BO3 и 4,0 мас.% Gd2O3

Impact of a Higgs boson at a mass of 126 GeV on the standard model with three and four fermion generations

We perform a comprehensive statistical analysis of the standard model (SM) with three and four generations using the latest Higgs search results from LHC and Tevatron, the electroweak precision observables measured at LEP and SLD, and the latest determinations of MW, mt, and αs. For the three-generation case we analyze the tensions in the electroweak fit by removing individual observables from the fit and comparing their predicted values with the measured ones. In particular, we discuss the impact of the Higgs search results on the deviations of the electroweak precision observables from their best-fit values. Our indirect prediction of the top mass is mt=175.7+3.0−2.2  GeV at 68.3% C.L., which is in good agreement with the direct measurement. We also plot the preferred area in the MW-mt plane. The best-fit Higgs boson mass is 126.0 GeV. For the case of the SM with a perturbative sequential fourth fermion generation (SM4) we discuss the deviations of the Higgs signal strengths from their best-fit values. The H→γγ signal strength now disagrees with its best-fit SM4 value at more than 4σ. We perform a likelihood-ratio test to compare the SM and SM4 and show that the SM4 is excluded at 5.3σ. Without the Tevatron data on H→bb¯ the significance drops to 4.8σ

Joint analysis of Higgs boson decays and electroweak precision observables in the standard model with a sequential fourth generation

We analyze the impact of LHC and Tevatron Higgs data on the viability of the standard model with a sequential fourth generation, assuming Dirac neutrinos and a Higgs mass of 125 GeV. To this end we perform a combined fit to the signal cross sections of pp→H→γγ, ZZ∗, WW∗ at the LHC, to pp¯→VH→Vbb¯ (V=W, Z) at the Tevatron and to the electroweak precision observables. Fixing the mass of the fourth-generation down-type quark b′ to 600 GeV we find best-fit values of mt′=632  GeV, ml4=113.6  GeV and mν4=58.0  GeV for the other fourth-generation fermion masses. We compare the χ2 values and pulls of the different observables in the three- and four-generation case and show that the data is better described by the three-generation standard model. We also investigate the effects of mixing between the third- and fourth-generation quarks and of a future increased lower bound on the fourth-generation charged lepton mass of 250 GeV

Genetic and Phenotypic Heterogeneity in Familial Lecithin: Cholesterol Acyltransferase (LCAT) Deficiency Six Newly Identified Defective Alleles Further Contribute to the Structural Heterogeneity in This Disease

The presence of lecithin:cholesterol acyltransferase (LCAT) deficiency in six probands from five families originating from four different countries was confirmed by the absence or near absence of LCAT activity. Also, other invariate symptoms of LCAT deficiency, a significant increase of unesterified cholesterol in plasma lipoproteins and the reduction of plasma HDLcholesterol to levels below one-tenth of normal, were present in all probands. In the probands from two families, no mass was detectable, while in others reduced amounts of LCAT mass indicated the presence of a functionally inactive protein. Sequence analysis identified homozygous missense or nonsense mutations in four probands. Two probands from one family both were found to be compound heterozygotes for a missense mutation and for a single base insertion causing a readin