Snapshot location for POD in control of a linear heat equation

In the present work, we study the approximation of a distributed optimal control problem for a linear heat equation with model order reduction based on Proper Orthogonal Decomposition (POD-MOR). We show that snapshot location for control problems is crucial in model reduction. For the determination of the time instances (snapshot locations) we utilize an a-posteriori error control concept which is based on a reformulation of the optimality system of the underlying optimal control problem as a second order in time and fourth order in space elliptic system. Finally, we present a numerical test to illustrate our approach. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Strengthening the security of authenticated key exchange against bad randomness

Recent history has revealed that many random number generators (RNGs) used in cryptographic algorithms and protocols were not providing appropriate randomness, either by accident or on purpose. Subsequently, researchers have proposed new algorithms and protocols that are less dependent on the RNG. One exception is that all prominent authenticated key exchange (AKE) protocols are insecure given bad randomness, even when using good long-term keying material. We analyse the security of AKE protocols in the presence of adversaries that can perform attacks based on chosen randomness, i.e., attacks in which the adversary controls the randomness used in protocol sessions. We propose novel stateful protocols, which modify memory shared among a user’s sessions, and show in what sense they are secure against this worst case randomness failure. We develop a stronger security notion for AKE protocols that captures the security that we can achieve under such failures, and prove that our main protocol is correct in this model. Our protocols make substantially weaker assumptions on the RNG than existing protocols.     

Explicit portfolio for unit-linked life insurance contracts with surrender option

Introducing a surrender option in unit-linked life insurance contracts leads to a dependence between the surrender time and the financial market. [J. Barbarin, Risk minimizing strategies for life insurance contracts with surrender option, Tech. rep., University of Louvain-La-Neuve, 2007] used a lot of concepts from credit risk to describe the surrender time in order to hedge such types of contracts. The basic assumption made by Barbarin is that the surrender time is not a stopping time with respect to the financial market.The goal of this article is to make the hedging strategies more explicit by introducing concrete processes for the risky asset and by restricting the hazard process to an absolutely continuous process.First, we assume that the risky asset follows a geometric Brownian motion. This extends the theory of [T. Møller, Risk-minimizing hedging strategies for insurance payment processes, Finance and Stochastics 5 (2001) 419–446], in that the random times of payment are not independent of the financial market. Second, the risky asset follows a Lévy process.For both cases, we assume the payment process contains a continuous payment stream until surrender or maturity and a payment at surrender or at maturity, whichever comes first.     

Luminescence centers in silicate and germanate glasses activated by bismuth

Concentration series of silicate and germanate glasses activated by bismuth are studied. It is shown that luminescence in the IR region is controlled by several active centers related to bismuth. Based on a comparison of spectroscopic characteristics of the studied glasses with the data previously obtained for chloride glass, the observed centers were identified as Bi⁺, Bi ₂ ⁴⁺ , and Bi ₅ ³⁺ in germanate glass and Bi⁺, Bi ₂ ⁴⁺ in silicate glass.     

Interaction between water-soluble peptidic CdSe/ZnS nanocrystals and membranes: formation of hybrid vesicles and condensed lamellar phases

Due to their tunable optical properties and their well-defined nanometric size, core/shell nanocrystals (quantum dots, QDs) are extensively used for the design of biomarkers as well as for the preparation of nanostructured hybrid materials. It is thus of great interest to understand their interaction with soft lipidic membranes. Here we present the synthesis of water-soluble peptide CdSe/ZnS QDs and their interaction with the fluid lipidic membrane of vesicles. The use of short peptides results in the formation of small QDs presenting both high fluorescence quantum yield and high colloidal stability as well as a mean hydrodynamical diameter of 10 nm. Their interaction with oppositely charged vesicles of various surface charge and size results in the formation of hybrid giant or large unilamellar vesicles covered with a densely packed layer of QDs without any vesicle rupture, as demonstrated by fluorescence resonance energy transfer experiments, zetametry, and optical microscopy. The adhesion of nanocrystals onto the vesicle membrane appears to be sterically limited and induces the reversion of the surface charge of the vesicles. Therefore, their interaction with small unilamellar vesicles induces the formation of a well-defined lamellar hybrid condensed phase in which the QDs are densely packed in the plane of the layers, as shown by freeze-fracture electron microscopy and small-angle X-ray scattering. In this structure, strong undulations of the bilayer maximize the electrostatic interaction between the QDs and the bilayers, as previously observed in the case of DNA polyelectrolytes interacting with small vesicles.     

Dicobalt hexacarbonyl complexes of alkynyl imines in a sequential Staudinger/Pauson-Khand process. A route to new fused tricyclic beta-lactams

Dicobalt hexacarbonyl complexes of alkynyl imines were allowed to react with ketenes via Staudinger reaction. Sequential [2 + 2] cycloaddition/Pauson-Khand reaction led to structurally new fused-tricyclic beta-lactams and fused-azabicyclic cyclopentenones. Chemoselectivity, scope, and limitation of the process were investigated.     

Polyphenols from Dichrostachys cinerea Fruits Anti-Inflammatory,Analgesic, and Antioxidant Capacity in Freund’s Adjuvant-Induced Arthritic Rat Model

Dichrostachys cinerea (L.) Wigth & Arn. (DC) is widely used in traditional medicine against several inflammatory diseases, especially rheumatoid arthritis, because of its antioxidant and anti-inflammatory effects. This study aimed to characterize the polyphenol-rich DC fruit extracts and investigate the analgesic, anti-inflammatory, and antioxidant effects in a rat inflammation model induced by complete Freund’s adjuvant (CFA). Water and ethanolic extracts were characterized using liquid chromatography coupled with mass spectrometry (LC-MS), Fourier-transform infrared (FTIR) spectroscopy, and gas chromatography coupled with mass spectrometry (GC-MS). The polyphenol-rich extracts were administered in three different concentrations for 30 days. Pain threshold, thermal hyperalgesia, edema, and serum biomarkers specific to inflammatory processes or oxidative stress were evaluated. Both extracts were rich in polyphenolic compounds, mainly flavan-3-ols, proanthocyanidins, and flavone glycosides, which had important in vitro antioxidant capacity. DC fruit extracts administration had the maximum antinociceptive and anti-inflammatory effects after one day since the CFA injection and showed promising results for long-term use as well. The measurement of pro-inflammatory cytokines, cortisol, and oxidative stress parameters showed that DC extracts significantly reduced these parameters, being dose and extract-type dependent. These results showed potential anti-inflammatory, analgesic, and antioxidative properties and revealed the necessity of using a standardized polyphenolic DC extract to avoid result variability.     

New insights into the polymerization of methyl methacrylate initiated by rare-earth borohydride complexes: a combined experimental and computational approach

Polymerization of methyl methacrylate (MMA) initiated by the rare-earth borohydride complexes [Ln(BH(4))(3)(thf)(3)] (Ln=Nd, Sm) or [Sm(BH(4))(Cp*)(2)(thf)] (Cp*=eta-C(5)Me(5)) proceeds at ambient temperature to give rather syndiotactic poly(methyl methacrylate) (PMMA) with molar masses M(n) higher than expected and quite broad molar mass distributions, which is consistent with a poor initiation efficiency. The polymerization of MMA was investigated by performing density functional theory (DFT) calculations on an eta-C(5)H(5) model metallocene and showed that in the reaction of [Eu(BH(4))(Cp)(2)] with MMA the borate [Eu(Cp)(2){(OBH(3))(OMe)C=C(Me)(2)}] (e-2) complex, which forms via the enolate [Eu(Cp)(2){O(OMe)C=C(Me)(2)}] (e), is calculated to be exergonic and is the most likely of all of the possible products. This product is favored because the reaction that leads to the formation of carboxylate [Eu(Cp)(2){OOC-C(Me)(=CH(2))}] (f) is thermodynamically favorable, but kinetically disfavored, and both of the potential products from a Markovnikov [Eu(Cp)(2){O(OMe)C-CH(Me)(CH(2)BH(3))}] (g) or anti-Markovnikov [Eu(Cp)(2){O(OMe)C-C(Me(2))(BH(3))}] (h) hydroboration reaction are also kinetically inaccessible. Similar computational results were obtained for the reaction of [Eu(BH(4))(3)] and MMA with all of the products showing extra stabilization. The DFT calculations performed by using [Eu(Cp)(2)(H)] to model the mechanism previously reported for the polymerization of MMA initiated by [Sm(Cp*)(2)(H)](2) confirmed the favorable exergonic formation of the intermediate [Eu(Cp)(2){O(OMe)C=C(Me)(2)}] (e') as the kinetic product, this enolate species ultimately leads to the formation of PMMA as experimentally observed. Replacing H by BH(4) thus prevents the 1,4-addition of the [Eu(BH(4))(Cp)(2)] borohydride ligand to the first incoming MMA molecule and instead favors the formation of the borate complex e-2. This intermediate is the somewhat active species in the polymerization of MMA initiated by the borohydride precursors [Ln(BH(4))(3)(thf)(3)] or [Sm(BH(4))(Cp*)(2)(thf)].     

Mechahism of the base promoted fragmentatiom of chloroacetylhydrazide

Experiments are described supporting the positions that the visible transient intermediate occurring during the fragmentation of chloroacetylhydrazide is the anion of acetyldiazene, and that the concurrent reduction is not a simple recombination reaction.