13 research outputs found
Modelling Specific Interest Rate Risk with Estimation of Missing Data
For the treatment of specific interest rate risk, a risk model is suggested, quantifying and combining both market and credit risk components consistently. The market risk model is based on credit spreads derived from traded bond prices. Though traded bond prices reveal a maximum amount of issuer specific information, illiquidity problems do not allow for classical parameter estimation in this context. To overcome this difficulty an efficient multiple imputation method is proposed that also quantifies the amount of risk associated with missing data. The credit risk component is based on event risk caused by correlated rating migrations of individual bonds using a Copula function approach.Statistical estimation with missing data, specific interest rate risk, multiple imputation, EM-algorithm, value at risk, copula functions,
Crystal structure of 12-benzylsulfanyl-2,9-dibromo-6H-dibenzo[b,g][1,8]naphthyridin-11-one
The heterotetracene skeleton of the title molecule, C23H14Br2N2OS, is defined by linear annulation of four six-membered rings, including two N heteroatoms. This moiety is nearly planar (r.m.s. deviation = 0.055 Å), with a slight twist of 4.1 (2)° between the two halves of the aromatic system. The dihedral angle between the least-squares plane of the skeleton and the benzyl group is 24.5 (3)°; the C—S—C angle involving the benzylsulfanyl group is 99.2 (4)°. In the crystal, molecules are π-stacked in an antiparallel fashion along [110], with a distance between the aromatic planes of 3.47 (2) Å. Intermolecular N—H...O hydrogen bonds form chains extending parallel to [001] and bridge the antiparallel interdigitated stacks of molecules
Crystal structure of 12-benzylsulfanyl-2,9-dibromo-6H-dibenzo[b,g][1,8]naphthyridin-11-one
The heterotetracene skeleton of the title molecule, C23H14Br2N2OS, is defined by linear annulation of four six-membered rings, including two N heteroatoms. This moiety is nearly planar (r.m.s. deviation = 0.055 Å), with a slight twist of 4.1 (2)° between the two halves of the aromatic system. The dihedral angle between the least-squares plane of the skeleton and the benzyl group is 24.5 (3)°; the C-S-C angle involving the benzylsulfanyl group is 99.2 (4)°. In the crystal, molecules are [pi]-stacked in an antiparallel fashion along [110], with a distance between the aromatic planes of 3.47 (2) Å. Intermolecular N-H...O hydrogen bonds form chains extending parallel to [001] and bridge the antiparallel interdigitated stacks of molecules
Diving into the Finestructure of Macroporous Polymer Foams Synthesized via Emulsion Templating: A Phase Diagram Study
During our studies
on emulsion-templated monodisperse polymer foams
we found significant differences in the finestructure if the locus
of initiation is changed. This motivated us to study the phase behavior
of the liquid template. Our studies indicate that the template consists
of droplets of three different length scales: The water droplets generated
via microfluidics (∼70 μm) are surrounded by a continuous
phase in which a w/o emulsion (≤100 nm) coexists with a w/o <i>micro</i>emulsion (∼5 nm). We speculate that the w/o-emulsion
droplets act as seeds for the porous finestructure observed in AIBN-initiated
polymer foams. We have experimental evidence that the w/o emulsion
inverts to an o/w emulsion with progressing polymerization. This explains
the granular texture observed in KPS-initiated polymer foams. The
control of the finestructure is important in the preparation of tailor-made
polymer foams because it directly impacts the material’s density
and thus, in turn, its mechanical stability
Solvent-dependent facile synthesis of diaryl selenides and biphenols employing selenium dioxide
Biphenols are important structure motifs for ligand systems in organic catalysis and are therefore included in the category of so-called “privileged ligands”. We have developed a new synthetic pathway to construct these structures by the use of selenium dioxide, a stable, powerful, and commercially available oxidizer. Our new, and easy to perform protocol gives rise to biphenols and diaryl selenides depending on the solvent employed. Oxidative treatment of phenols in acetic acid yields the corresponding biphenols, whereas conversion in pyridine results in the preferred formation of diaryl selenides. As a consequence, we were able to isolate a broad scope of novel diaryl selenides, which could act as pincer-like ligands with further applications in organic synthesis or as ligands in transition metal catalysis
The Pharmacogenetic Footprint of ACE Inhibition: A Population-Based Metabolomics Study.
Angiotensin-I-converting enzyme (ACE) inhibitors are an important class of antihypertensives whose action on the human organism is still not fully understood. Although it is known that ACE especially cleaves COOH-terminal dipeptides from active polypeptides, the whole range of substrates and products is still unknown. When analyzing the action of ACE inhibitors, effects of genetic variation on metabolism need to be considered since genetic variance in the ACE gene locus was found to be associated with ACE-concentration in blood as well as with changes in the metabolic profiles of a general population. To investigate the interactions between genetic variance at the ACE-locus and the influence of ACE-therapy on the metabolic status we analyzed 517 metabolites in 1,361 participants from the KORA F4 study. We replicated our results in 1,964 individuals from TwinsUK. We observed differences in the concentration of five dipeptides and three ratios of di- and oligopeptides between ACE inhibitor users and non-users that were genotype dependent. Such changes in the concentration affected major homozygotes, and to a lesser extent heterozygotes, while minor homozygotes showed no or only small changes in the metabolite status. Two of these resulting dipeptides, namely aspartylphenylalanine and phenylalanylserine, showed significant associations with blood pressure which qualifies them-and perhaps also the other dipeptides-as readouts of ACE-activity. Since so far ACE activity measurement is substrate specific due to the usage of only one oligopeptide, taking several dipeptides as potential products of ACE into account may provide a broader picture of the ACE activity
Inverse normalized values of aspartylphenylalanine for KORA and TwinsUK (AA: major homozygotes, AG: heterozygotes, GG minor homozygotes).
<p>Inverse normalized values of aspartylphenylalanine for KORA and TwinsUK (AA: major homozygotes, AG: heterozygotes, GG minor homozygotes).</p
Significant results from the KORA F4 analysis for rs4329.
<p>Significant results from the KORA F4 analysis for rs4329.</p
Summary of here discussed genotype dependent polypeptide cleavage catalyzed by ACE.
<p>Blue coloring: health effect of the respective polypeptide; green: measured metabolites.</p