On Karnaugh maps and magic squares

In 1953, Karnaugh maps were developed at the Harvard Computation Laboratory for the minimization of Boolean algebraic expressions (as an approach to logic circuit synthesis) [5].     

Modeling business processes with BPEL4WS

Business Process Execution Language for Web Services (BPEL4WS) allows defining both, business processes that make use of Web services, and business processes that externalize their functionality as Web services. This short paper introduces the basic language elements of BPEL4WS using a simple example. The concepts underlying the language are briefly explained: establishing bilateral partnerships, correlating messages and processes, defining the order of the activities of a business process, event handling, handling exceptions via long-running transactions, and the usage of BPEL4WS in pure B2B scenarios. The paper finishes off by presenting the resulting application structure and the resulting economical implications.     

Approximating minimum cocolorings

A cocoloring of a graph G is a partition of the vertex set of G such that each set of the partition is either a clique or an independent set in G. Some special cases of the minimum cocoloring problem are of particular interest.We provide polynomial-time algorithms to approximate a minimum cocoloring on graphs, partially ordered sets and sequences. In particular, we obtain an efficient algorithm to approximate within a factor of 1.71 a minimum partition of a partially ordered set into chains and antichains, and a minimum partition of a sequence into increasing and decreasing subsequences.     

On-line characterization of organic aerosols formed from biogenic precursors using atmospheric pressure chemical ionization mass spectrometry

A method to investigate the chemical composition of organic aerosols formed from biogenic hydrocarbon oxidation using atmospheric pressure chemical ionization mass spectrometry (APCI/MS) is described. The method involves the direct introduction of aerosol particles into the ion source of the mass spectrometer. Using this technique, reaction monitoring experiments of alpha-pinene ozonolysis show the formation of hetero- and homomolecular cluster anions (dimers) of the primary oxidation products (multifunctional carboxylic acids). Since the formation of dimers plays a profound role in new particle formation processes by homogeneous nucleation in the atmosphere and, at the same time, is an intrinsic feature of APCI, it is essential to differentiate between both processes when on-line APCI/MS is applied. In this paper, we compare the results from the investigations of organic aerosols and artificially generated dimer cluster ions of the same compounds using identical ionization conditions. The clusters and their formation processes are characterized by varying the analyte concentration, investigating the thermal stability of dimers, and studying collisional activation properties of both ion species. The investigations show a significant difference in ion stability: dimer anions measured on-line have an estimated stability that is 20 kJ mol(-1) higher than that of the corresponding artificially generated cluster ions. Hence, the technique provides the possibility to accurately characterize dimers as ionized reaction products from biogenic hydrocarbon oxidation and allows an insight into the process of new-particle formation by homogeneous nucleation.     

Vergleichsstudie von Methoden der Flächenpressungsmessung

Measurements of contact stresses between elastic bodies are of great importance not only in mechanical and civil engineering but also in medicine, especially in orthopedic fields. On the one hand there are a lot of methods making use of electrical effects and on the other hand there are imprint methods. The accuracy of measuring results depends mainly on the influences of thickness and stiffness of the inserted measuring sheets between the bodies in contact. In this study effects of the elastic properties of the inserted sheet with respect to the stiffness of the elastic bodies were investigated. For this purpose the following well known load cases were chosen:

1. rigid cylindrical body pressed on an elastic half-space,
2. Hertz-problem of two spherical bodies in contact.

For both cases analytical solutions and FE calculations are compared with experimental results.     

Managing Structural Information by Higher-Order Colored Unification

Coloring terms (rippling) is a technique developed for inductive theorem proving that uses syntactic differences of terms to guide the proof search. Annotations (colors) to symbol occurrences in terms are used to maintain this information. This technique has several advantages; for example, it is highly goal oriented and involves little search. In this paper we give a general formalization of coloring terms in a higher-order setting. We introduce a simply typed calculus with color annotations and present appropriate algorithms for the general, pre-, and pattern unification problems. Our work is a formal basis to the implementation of rippling in a higher-order setting, which is required, for example, in the case of middle-out reasoning. Another application is in the construction of natural the language semantics, where the color annotations rule out linguistically invalid readings that are possible using standard higher-order unification.     

Dominant effects of the bcr-abl oncogene on Drosophila morphogenesis

The Ras protein and its homolog, Rap1A, have an identical "effector region" (residues 32-40) preceded by Asp30-Glu31 and Glu30-Lys31, respectively. In the complex of the "Ras-like" E30D/K31E mutant Rap1A with the Ras-binding domain (RBD), residues 51-131 of Raf-1, Glu31 in Rap1A forms a tight salt bridge with Lys84 in Raf-1. However, we have recently found that Raf-1 RBD binding of Ras is indeed reduced by the E31K mutation, but is not affected by the E31A mutation. Here, the "Rap1A-like" D30E/E31K mutant of Ras was prepared and shown to bind the Raf-1 RBD less strongly than wild-type Ras, but slightly more tightly than the E31K mutant. The backbone 1H, 13C, and 15N magnetic resonances of the Raf-1 RBD were assigned in complexes with the wild-type and D30E/E31K mutant Ras proteins in the guanosine 5'-O-(beta,gamma-imidotriphosphate)-bound form. The Lys84 residue in the Raf-1 RBD exhibited a large change in chemical shift upon binding wild-type Ras, suggesting that Lys84 interacts with wild-type Ras. The D30E/E31K mutant of Ras caused nearly the same perturbations in Raf-1 chemical shifts, including that of Lys84. We hypothesized that Glu31 in Ras may not be the major salt bridge partner of Lys84 in Raf-1. A molecular dynamics simulation of a model structure of the Raf-1 RBD.Ras.GTP complex suggested that Lys84 in Raf-1 might instead form a tight salt bridge with Asp33 in Ras. Consistent with this, the D33A mutation in Ras greatly reduced its Raf-I RBD binding activity. We conclude that the major salt bridge partner of Lys84 in Raf-1 may be Asp33 in Ras.