A Reference Architecture for Electronic Business-to-Business Collaboration Setup and Enactment Systems

The question what a business-to-business (B2B) collaboration setup and enactment application-system should look like remains open. An important element of such collaboration constitutes the inter-organizational disclosure of business-process details so that the opposing parties may protect their business secrets. For that purpose, eSourcing [37] has been developed as a general businessprocess collaboration concept in the framework of the EU research project Cross- Work. The eSourcing characteristics are guiding for the design and evaluation of an eSourcing Reference Architecture (eSRA) that serves as a starting point for software developers of B2B-collaboration systems. In this paper we present the results of a scenario-based evaluation method conducted with the earlier specified eSourcing Architecture (eSA) that generates as results risks, sensitivity, and tradeoff points that must be paid attention to if eSA is implemented. Additionally, the evaluation method detects shortcomings of eSA in terms of integrated components that are required for electronic B2B-collaboration. The evaluation results are used for the specification of eSRA, which comprises all extensions for incorporating the results of the scenario-based evaluation, on three refinement levels.

Exploring a framework for advanced electronic business transactions

With the emergence of service-oriented computing technology, companies embrace new ways of carrying out business transactions electronically. Since the parties involved in an electronic business transaction (eBT) manage a heterogeneous information-systems infrastructure within their organizational domains, the collaboration complexity is considerable and safeguarding an interorganizational collaboration with an eBT is difficult, but of high significance. This paper describes a conceptual framework that pays attention to the complexities of an eBT and its differentiating characteristics that go further than traditional database transactions. Since the eBT is a framework that comprises separate levels, pre-existing transaction concepts are explored for populating the respective levels. To show the feasibility of the described eBT framework, industry initiatives that are aspiring to become business-transaction standards, are checked for eBT compatible characteristics. Since realizing an eBT framework raises many tricky issues, the paper maps out important research areas that require scientific attention. Essentially, it is required to investigate how the business semantics influences the nature of an eBT throughout its lifecycle.

Analysis of conjugate laminar mixed convection cooling in a shrouded array of electronic components

The temperature variation in the insulation around an electronic component, mounted on a horizontal circuit board is studied numerically. The flow is assumed to be laminar and fully developed. The effect of mixed convection and two different types of insulation are considered. The mass, momentum and energy conservation equations in the fluid and conduction equation in the insulation are solved using the SIMPLER algorithm. Computations are carried out for liquid Freon and water, for different conductivity ratios, and different Rayleigh numbers. It is demonstrated that the temperature variation within the insulation becomes important when the thermal conductivity of the insulation is less than ten times the thermal conductivity of the cooling medium.

Theory of the effects of destruction of localization by inelastic scattering in the resistivity of pure thin potassium wires

Measurements of the electrical resistivity of thin potassium wires at temperatures near 1 K have revealed a minimum in the resistivity as a function of temperature. By proposing that the electrons in these wires have undergone localization, albeit with large localization length, and that inelastic-scattering events destroy the coherence of that state, we can explain both the magnitude and shape of the temperature-dependent resistivity data. Localization of electrons in these wires is to be expected because, due to the high purity of the potassium, the elastic mean free path is comparable to the diameters of the thinnest samples, making the Thouless length lT (or inelastic diffusion length) much larger than the diameter, so that the wire is effectively one dimensional. The inelastic events effectively break the wire into a series of localized segments, whose resistances can be added to obtain the total resistance of the wire. The ensemble-averaged resistance for all possible segmented wires, weighted with a Poisson distribution of inelastic-scattering lengths along the wire, yields a length dependence for the resistance that is proportional to [L3/lin(T)], provided that lin(T)?L, where L is the sample length and lin(T) is some effective temperature-dependent one-dimensional inelastic-scattering length. A more sophisticated approach using a Poisson distribution in inelastic-scattering times, which takes into account the diffusive motion of the electrons along the wire through the Thouless length, yields a length- and temperature-dependent resistivity proportional to (L/lT)4 under appropriate conditions. Inelastic-scattering lifetimes are inferred from the temperature-dependent bulk resistivities (i.e., those of thicker, effectively three-dimensional samples), assuming that a minimum amount of energy must be exchanged for a collision to be effective in destroying the phase coherence of the localized state. If the dominant inelastic mechanism is electron-electron scattering, then our result, given the appropriate choice of the channel number parameter, is consistent with the data. If electron-phason scattering were of comparable importance, then our results would remain consistent. However, the inelastic-scattering lifetime inferred from bulk resistivity data is too short. This is because the electron-phason mechanism dominates in the inelastic-scattering rate, although the two mechanisms may be of comparable importance for the bulk resistivity. Possible reasons why the electron-phason mechanism might be less effective in thin wires than in bulk are discussed.

Electronic states in a disordered metal: Magnetotransport in doped germanium

We observe a sharp feature in the ultra-low-temperature magnetoconductivity of degenerately doped Ge:Sb at H∼25 kOe, which is robust up to at least three times the critical density for the insulator-metal transition. This field corresponds to a low-energy scale characteristic of the special nature of antimony donors in germanium. Its presence and sensitivity to uniaxial stress confirm the notion of metallic impurity bands in doped germanium.

Effect of hole localization on Madelung potential of YBa2Cu3O7

The Madelung potential and formation energy of the superconducting compound YBa2Cu3O7 have been computed for hole localization at different sites in the crystal. The cases considered include Cu3+ ion at Cu(1) and Cu(2) sites, O− ion at O(1), O(2), O(3) and O(4) sites and combinations of O− and Cu3+ ions at O(4) and Cu(1) and O(2,3) and Cu(2) sites. The two lowest-energy configurations correspond to Cu3+ ion at Cu(1) site and O− ion at O(4) site. The difference in formation energy between those configurations is relatively small. The next preferred configuration corresponds to simultaneous partial localization of the hole at Cu (1) site and O(1) site. Other configurations are much less stable. The results suggest a resonating or fluctuating valence model for YBa2Cu3O7.

Electronic Structure of and the Metal-Insulator Transition in La1-xSrxCoO3-δ: A Soft-X-Ray Absorption Study

We report the soft-X-ray absorption spectra at the oxygen K-edge of La1-xSrxCoO3-δ (x = 0.0, 0.1, 0.2, 0.3 and 0.4) series with experimentally determined δ values. We show that the doping of holes by replacing La3+ with Sr2+ induces states within the band gap of the insulating undoped compound for small x and these doped states have a very substantial oxygen 2p character. This indicates that the insulating compounds belong to the charge transfer insulator regime. With increasing Sr content, the doped states broaden into a band overlapping the top of the primarily oxygen p-derived band, leading to an insulator-metal transition at x ≥ 0.2.

Electronic absorption and emission spectroscopic investigations of the interaction of the fullerenes, C60 and C70, with amines and aromatic molecules

Electronic absorption spectroscopy and fluorescence spectroscopy have been used to investigate the interaction of the fullerenes C60 and C70 with diethylaniline, and with aromatic solvents such as benzene. C60 interacts weakly with aromatic amines in the ground state while C70 does not interact at all. Steady state fluorescence emission and lifetime measurements show that both C60 and C70 form excited state complexes (exciplexes) with the amines in non-aromatic solvents such as methylcyclohexane, but not in benzene. In benzene, only fluorescence quenching is observed due to the interaction between the π systems of the aromatic solvent and the fullerene in the ground state. This is also borne out by the systematic study of solvent effects on the absorption and emission spectra of the fullerenes.

Electronic excitations and alternation of conjugated polymers

The electronic excitations and fluorescence of conjugated polymers are related to large or small alternation ? of the transfer integrals t(1 ± ?) along the backbone. The fluorescence of polysilanes (PSs) and poly (para-phenylenevinylene (PPV) is linked to large ?, which places the one-photon gap Eg below the lowest two-photon gap Ea and reduces distortions due to electron-phonon (e-p) coupling. In contrast to small ? not, vert, similar 0.1 in ?-conjugated polymers, such as polyacetylene (PA), para-conjugated phenyls lead to an extended ?-system with increased alternation, to states localized on each ring and to charge-transfer excitations between them. Surprisingly good agreement is found between semiempirical parametric method 3 (PM3) bond lengths and exact Pariser-Parr-Pople (PPP) ?-bond orders for trans-stilbene, where the PPV bipolarons are confined to two phenyls. Stilbene spectra are consistent with increased alternation and small e-p distortions.

Electronic structure of La1-xSrxFeO3

We have investigated the electronic structure of well-characterized samples of La1-xSrxFeO3 (x=0.0�0.4) by x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy, bremsstrahlung isochromat (BI) spectroscopy, and Auger electron spectroscopy. We find systematic behavior in the occupied and unoccupied density of states reflecting changes in the electronic structure on hole doping via Sr substitution as well as providing estimates for different interaction strengths. The spectral features, particularly of the unoccupied states obtained from BI spectra, indicate the probable reason for the absence of an insulator-metal transition in this series. Analysis of the Auger spectra provides the estimates of the on-site effective Coulomb interaction strengths in Fe 3d and O 2p states. The parameter values for the bare charge-transfer energy ? and the Fe 3d�O 2p hybridization strength t? for LaFeO3 are obtained from an analysis of the Fe 2p core-level XPS in terms of a model many-body calculation. We discuss the character of the ground state in LaFeO3 as well as the nature of the doped hole states in La1-xSrxFeO3, based on these parameter values.

Moonlighting Proteins of Lactobacillus crispatus : Extracellular Localization, Cell Wall Anchoring and Interactions with the Host

Moonlighting functions have been described for several proteins previously thought to localize exclusively in the cytoplasm of bacterial or eukaryotic cells. Moonlighting proteins usually perform conserved functions, e. g. in glycolysis or as chaperonins, and their traditional and moonlighting function(s) usually localize to different cell compartments. The most characterized moonlighting proteins in Grampositive bacteria are the glycolytic enzymes enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which function in bacteria-host interactions, e. g. as adhesins or plasminogen receptors. Research on bacterial moonlighting proteins has focused on Gram-positive bacterial pathogens, where many of their functions have been associated with bacterial virulence. In this thesis work I show that also species of the genus Lactobacillus have moonlighting proteins that carry out functions earlier associated with bacterial virulence only. I identified enolase, GAPDH, glutamine synthetase (GS), and glucose-6-phosphate isomerase (GPI) as moonlighting proteins of Lactobacillus crispatus strain ST1 and demonstrated that they are associated with cell surface and easily released from the cell surface into incubation buffer. I also showed that these lactobacillar proteins moonlight either as adhesins with affinity for basement membrane and extracellular matrix proteins or as plasminogen receptors. The mechanisms of surface translocation and anchoring of bacterial moonlighting proteins have remained enigmatic. In this work, the surface localization of enolase, GAPDH, GS and GPI was shown to depend on environmental factors. The members of the genus Lactobacillus are fermentative organisms that lower the ambient pH by producing lactic acid. At acidic pH enolase, GAPDH, GS and GPI were associated with the cell surface, whereas at neutral pH they were released into the buffer. The release did not involve de novo protein synthesis. I showed that purified recombinant His6-enolase, His6-GAPDH, His6-GS and His6-GPI reassociate with cell wall and bind in vitro to lipoteichoic acids at acidic pH. The in-vitro binding of these proteins localizes to cell division septa and cell poles. I also show that the release of moonlighting proteins is enhanced in the presence of cathelicidin LL- 37, which is an antimicrobial peptide and a central part of the innate immunity defence. I found that the LL-37-induced detachment of moonlighting proteins from cell surface is associated with cell wall permeabilization by LL-37. The results in this thesis work are compatible with the hypothesis that the moonlighting proteins of L. crispatus associate to the cell wall via electrostatic or ionic interactions and that they are released into surroundings in stress conditions. Their surface translocation is, at least in part, a result from their release from dead or permeabilized cells and subsequent reassociation onto the cell wall. The results of this thesis show that lactobacillar cells rapidly change their surface architecture in response to environmental factors and that these changes influence bacterial interactions with the host.

NDDO-based CI methods for the prediction of electronic spectra and sum-over-states molecular hyperpolarization

NDDO-based (AM1) configuration interaction (CI) calculations have been used to calculate the wavelength and oscillator strengths of electronic absorptions in organic molecules and the results used in a sum-over-states treatment to calculate second-order-hyperpolarizabilities. The results for both spectra and hyperpolarizabilities are of acceptable quality as long as a suitable CI-expansion is used. We have found that using an active space of eight electrons in eight orbitals and including all single and pair-double excitations in the CI leads to results that agree well with experiment and that do not change significantly with increasing active space for most organic molecules. Calculated second-order hyperpolarizabilities using this type of CI within a sum-over-states calculation appear to be of useful accuracy.