254 research outputs found
Distributed enterprise search using software agents
In this paper we introduce a distributed information retrieval
system using agent-based technology. In this multiagent
system, each agent has its own specific task and can
be used to handle a specific document repository. The system
is designed to automatically comply with access restriction
rules that are normally enforced in companies. It is
used in the administration offices of the German capital city
Berlin where it serves as a testbed for further research on
aggregated search in an enterprise environment with roughly
50,000 employees
Nyt fermenteringsanlæg skal accelerere udvikling af bæredygtig produktion af lægemidler og kemikalier
Comparing Gravitational Waveform Extrapolation to Cauchy-Characteristic Extraction in Binary Black Hole Simulations
We extract gravitational waveforms from numerical simulations of black hole
binaries computed using the Spectral Einstein Code. We compare two extraction
methods: direct construction of the Newman-Penrose (NP) scalar at a
finite distance from the source and Cauchy-characteristic extraction (CCE). The
direct NP approach is simpler than CCE, but NP waveforms can be contaminated by
near-zone effects---unless the waves are extracted at several distances from
the source and extrapolated to infinity. Even then, the resulting waveforms can
in principle be contaminated by gauge effects. In contrast, CCE directly
provides, by construction, gauge-invariant waveforms at future null infinity.
We verify the gauge invariance of CCE by running the same physical simulation
using two different gauge conditions. We find that these two gauge conditions
produce the same CCE waveforms but show differences in extrapolated-
waveforms. We examine data from several different binary configurations and
measure the dominant sources of error in the extrapolated- and CCE
waveforms. In some cases, we find that NP waveforms extrapolated to infinity
agree with the corresponding CCE waveforms to within the estimated error bars.
However, we find that in other cases extrapolated and CCE waveforms disagree,
most notably for "memory" modes.Comment: 26 pages, 20 figure
Linear Thermal Expansion Coefficient of the NaCl Phase of CsCl
Cesium chloride undergoes a phase change from the low-temperature CsCI structure to the high-temperature NaCI structure at about 469°C.l There is a volume increase of about 16% when the NaCI structure appears.1 The nature of the transition is of interest, as are the physical properties of the high-temperature phase. If sufficient high-temperature phase data are available for CsCI, calculations of the heat of transition can be made more accurately
Probing atom-surface interactions by diffraction of Bose-Einstein condensates
In this article we analyze the Casimir-Polder interaction of atoms with a
solid grating and an additional repulsive interaction between the atoms and the
grating in the presence of an external laser source. The combined potential
landscape above the solid body is probed locally by diffraction of
Bose-Einstein condensates. Measured diffraction efficiencies reveal information
about the shape of the Casimir-Polder interaction and allow us to discern
between models based on a pairwise-summation (Hamaker) approach and Lifshitz
theory.Comment: 5 pages, 4 figure
Nationale Industriepolitik - brauchen wir nationale Champions?
Sollte der Staat mittels einer aktiven Industriepolitik, die die Belange der Wettbewerbspolitik hintan stellt, Unternehmen "züchten", die im Wettbewerb auf dem Weltmarkt bestehen können? Für Prof. Dr. Juergen Donges, Universität zu Köln, stoßen staatliche Initiativen zum Champions-Building oder Champions-Defending sehr schnell an Grenzen der Wirksamkeit. Der bessere Weg sei die Schaffung von Rahmenbedingungen, bei denen die Unternehmen einen starken Anreiz haben, im Inland in Forschung und Entwicklung zu investieren und eine rasche Umsetzung von Forschungsergebnissen in neue, marktfähige Produkte zu erreichen. Nach Ansicht von Dr. Dieter Heuskel, Boston Consulting Group, "steht (es) außer Frage, dass die Entwicklung international wettbewerbsfähiger Unternehmensstrategien in erster Linie Aufgabe des Managements ist. Dazu zählt auch die Entscheidung über Investitionen und Standorte. Es bleibt jedoch Aufgabe der Politik - sowohl der nationalen wie vor allem der europäischen Wirtschaftspolitik -, die Wettbewerbsbedingungen so zu gestalten, dass europäische Unternehmen im internationalen Wettbewerb wie auch an ihrem Ausgangsstandort "bewegungsfähig" sind und strategisch agieren können." Für Dr. Kurt Christian Scheel, Bundesverband der Deutschen Industrie, Berlin, ist die Frage nicht, ob wir nationale Champions brauchen, sondern: "Natürlich sind Champions wünschenswert. Aber: Diese sollen sich aus eigener Kraft nach den Gesetzen des Marktes entwickeln. Nur der Markt kann entscheiden, welches Unternehmen wächst und welches scheitert. Die Aufgabe des Staats ist es, durch geeignete Rahmenbedingungen dafür zu sorgen, dass Deutschland für Investitionen attraktiv bleibt, die Grundlage dieses Wachstums sind."Industriepolitik, Wettbewerb, Forschung, Internationaler Wettbewerb, Wachstumstheorie
Towards substrate-reagent interaction of Lochmann-Schlosser bases in THF: bridging THF hides potential reaction site of a chiral superbase
The metalation of N,N-dimethylaminomethylferrocene in THF by the superbasic mixture of nBuLi/KOtBu proceeds readily at low temperatures to afford a bimetallic Li2K2 aggregate containing ferrocenyl anions and tert-butoxide. Starting from an enantiomerically enriched ortho-lithiated aminomethylferrocene, an enantiomerically pure superbase can be prepared. The molecular compound exhibits superbasic behavior deprotonating N,N-dimethylbenzylamine in the α-position and is also capable of deprotonating toluene. Quantum chemical calculations provide insight into the role of the bridging THF molecule to the possible substrate–reagent interaction. In addition, a benzylpotassium alkoxide adduct gives a closer look into the corresponding reaction site of the Lochmann–Schlosser base that is reported herein
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