Optisch aktive Amine durch Lipase-katalysierte Methoxyacetylierung

Optically Active Amines via Lipase-Catalyzed Methoxyacetylation Racemic amines can be efficiently resolved using ethylmethoxyacetate as acylating agent in a lipase-catalyzed reaction. The reaction of 1-phenyethylamine with ethylmethoxyacetate in the presence of a lipase from Burkholderia plantarii is presented. Excellent yields and selectivity and minimal amount of enzyme characterize this new process.     

Survey on test data generation tools

Automating the process of software testing is a very popular research topic and of real interest to industry. Test automation can take part on different levels, e.g., test execution, test case generation, test data generation. This survey gives an overview of state-of-the art test data generation tools, either academic or commercial. The survey focuses on white- and gray-box techniques. The list of existing tools was filtered with respect to their public availability, their maturity, and activity. The remaining seven tools, i.e., AgitarOne, CodePro AnalytiX, AutoTest, C++test, Jtest, RANDOOP, and PEX, are briefly introduced and their evaluation results are summarized. For the evaluation we defined 31 benchmark tests, which check the tools capabilities to generate test data that satisfies a given specification: 24 primitive type benchmarks and 7 non-primitive type and more complex with respect to the specification benchmarks. Most of the commercial tools implement a test data strategy that uses constant values found in the method under test or values that are slightly modified by means of mathematical operations. This strategy turns out to be very effective. In general, all tools that combine multiple techniques perform very well. For example PEX uses constraint solving techniques, but in cases where the constraint solver reaches its limitations it uses random based techniques to overcome those limitations. Especially, the two commercial tools AgitarOne and PEX that combine multiple approaches to test data generation are able to pass all 31 tests. This survey reflects the status in 2011.     

The impact of the number of parallel warehouses on total inventory

In the strategic design of a distribution system, the right number of stock points for the various products is an important question. In the past decade, a strong trend in the consumer goods industry led to centralizing the inventory in a single echelon consisting of a few parallel warehouses or even a single distribution center for a Europe-wide distribution system. Centralizing inventory is justified by the reduction in total stock which mostly overcompensates the increasing transportation cost. The effect of centralization is usually described by the “Square Root Law”, stating that the total stock increases with the square root of the number of stock points. However, in the usual case where the warehouses are replenished in full truck loads and where a given fill rate has to be satisfied, the Square Root Law is not valid. This paper explores that case. It establishes functional relationships between the demand to be served by a warehouse and the necessary safety and cycle stock for various demand settings and control policies, using an approximation of the normal loss function and its inverse. As a consequence, the impact of the number of parallel warehouses on the total stock can be derived. The results can be used as tools in network design models.     

Vertrauensvolle E-Mail-Kommunikation

Der ?elektronische Brief“ bzw. die elektronische Mail (E-Mail) ist seit über 30 Jahren im privaten wie beruflichen Umfeld im Einsatz. Behörden, Steuerbüros, Krankenhäuser, Finanzinstitute und viele weitere Gruppen versenden und empfangen E-Mails, um Informationen auszutauschen. Innerhalb kurzer Zeit findet eine E-Mail ihren Weg vom Sender in Deutschland zum Empfänger in beispielsweise den USA. Wie funktioniert das? Und was hat es mit E-Mail-Verschlüsselung auf sich? Dieser Artikel betrachtet die grundlegende technische Funktionsweise der E-Mail sowie Hintergründe und Funktionsweise der Verschlüsselung mit S/MIME und PGP.