Fette

Ohne Zusammenfassung     

BMO from dyadic BMO on the bidisc

We generalize to the bidisc a theorem of Garnett and Jones relatingthe space BMO of functions of bounded mean oscillation to itsmartingale counterpart, dyadic BMO. Namely, translation-averagesof suitable families of dyadic BMO functions belong to BMO.As a corollary, we deduce a biparameter version of a theoremof Burgess Davis connecting the Hardy space H¹ to martingaleH¹. We also prove the analogs of the theorem of Garnett andJones in the one-parameter and biparameter VMO spaces of functionsof vanishing mean oscillation.     

Systemic risk elicitation: Using causal maps to engage stakeholders and build a comprehensive view of risks

As evidenced through both a historical and contemporary number of reported over-runs, managing projects can be a risky business. Managers are faced with the need to effectively work with a multitude of parties and deal with a wealth of interlocking uncertainties. This paper describes a modelling process developed to assist managers facing such situations. The process helps managers to develop a comprehensive appreciation of risks and gain an understanding of the impact of the interactions between these risks through explicitly engaging a wide stakeholder base using a group support system and causal mapping process. Using a real case the paper describes the modelling process and outcomes along with its implications, before reflecting on the insights, limitations and future research.     

Bayesian inference of the resonance content of p(γ,K+)Λ

A bayesian analysis of the world's p(γ,K^+)Λ data is presented. From the proposed selection of 11 resonances, we find that the following nucleon resonances have the highest probability of contributing to the reaction: S11(1535), S11(1650), F15(1680), P13(1720), D13(1900), P13(1900), P11(1900), and F15(2000). We adopt a Regge-plus-resonance framework featuring consistent couplings for nucleon resonances up to spin J=5/2. We evaluate all possible combinations of 11 candidate resonances. The best model is selected from the 2048 model variants by calculating the bayesian evidence values against the world's p(γ,K+)Λ data.     

Characterization of nucleobase-amino acid stacking interactions utilized by a DNA repair enzyme

The present work characterizes the gas-phase stacking interactions between four aromatic amino acid residues (histidine, phenylalanine, tyrosine, and tryptophan) and adenine or 3-methyladenine due to the proposed utilization of these interactions by enzymes that repair DNA alkylation damage. The MP2 potential energy surfaces of the stacked dimers are considered as a function of four variables (vertical displacement, angle of rotation, horizontal displacement, and tilt angle) using a variety of basis sets. It is found that the maximum stacking interaction energy decreases with the amino acid according to TRP > TYR approximately HIS > PHE for both nucleobases. However, the magnitude of the stacking interaction significantly increases upon alkylation (by 50-115%). Comparison of the stacking energies calculated using our surface scans to those estimated from experimental crystal structures indicates that the stacking interactions within the active site of 3-methyladenine DNA glycosylase can account for 65-75% of the maximum possible stacking interaction between the relevant molecules. The decrease in stacking in the crystal structure arises due to significant differences in the relative orientations of the nucleobase and amino acid. Nevertheless, alkylation is found to significantly increase the stacking energy when the crystal structure geometries are considered. Our calculations provide computational support for suggestions that alkylation enhances the stacking interactions within the active site of DNA repair enzymes, and they give a measure of the magnitude of this enhancement. Our results suggest that alkylation likely plays a more important role in substrate identification and removal than the nature of the aromatic amino acid that interacts with the substrate via stacking interactions.     

Determination of semicarbazide in baby food by liquid chromatography/tandem mass spectrometry: interlaboratory validation study

An interlaboratory validation study funded by the European Commission, Directorate General for Health and Consumer Protection (DG SANCO), was conducted to evaluate the effectiveness of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of semicarbazide (SEM) in different types of baby food at a possible future European regulatory limit (10 ng/g). The test portion of the sample was extracted with hydrochloric acid, and the analyte was derivatized with 2-nitrobenzaldehyde, with 1,2-[15N2, 13C] SEM as an internal standard. The extract was neutralized and then purified on a solid-phase extraction cartridge. The SEM was determined by reversed-phase LC with detection by MS/MS. Apple puree, rice pudding, and meat/vegetable meal baby food materials, spiked with SEM at levels of about 3, 10, and 30 ng/g, respectively, were sent to 20 laboratories in 12 different European countries, which submitted results from 17 participants. Recoveries ranged from 88.8 to 106.1%. Based on results for spiked samples (blind pairs at 3 levels), the relative standard deviations for repeatability (RSDr) ranged from 4.2 to 6.9% and the relative standard deviations for reproducibility (RSDR) ranged from 16.6 to 24.3%. The method showed acceptable within- and between-laboratory precision for all 3 matrixes, as evidenced by HorRat values, at the target levels for the determination of SEM.     

In vivo quantification of citrate concentration and water T2 relaxation time of the pathologic prostate gland using H MRS and MRI

We have previously reported a striking correlation between water T₂ relaxation time and citrate concentration in the normal prostate (Liney G.P.; Lowry M.; Turnbull L.W.; Manton D.J.; Knowles A.J.; Blackband S.J.; Horsman A. Proton MR T₂ maps correlate with the citrate concentration in the prostate. NMR Biomed. 9:59–64; 1996). In this study we present data from similar studies of the pathologic gland. The findings support the hypothesis that measurement of both citrate concentration and water T₂ relaxation time in vivo may aid the differentiation of prostatic carcinoma from benign disease and normal tissue.     

Multiple Instantons Representing Higher-Order Chern–Pontryagin Classes,II

This paper is a continuation of an earlier study on the generalized Yang–Mills instantons over 4m-dimensional spheres. We will first present a discussion on the generalized Yang–Mills equations, the higher-order Chern–Pontryagin classes, c _2m , and the self-dual or anti-self-dual equations. We will then obtain some sharp asymptotic estimates for the self-dual or anti-self-dual equations within the Witten–Tchrakian framework which relates the integer value of c _2m to the number of vortices of the solution to a reduced 2-dimensional Abelian Higgs system over the Poincaré half-plane. We will prove that, indeed, for any integer N, there exists a 2|N|-parameter family of the generalized self-dual or anti-self-dual instantons realizing the topology c _2m =N. Furthermore, for the purpose of accommodating more general solutions, we establish a removable singularity theorem which enables us to extend the solutions obtained on a 4m-dimensional Euclidean space with an integral bound to the Hölder continuous solutions on a 4m-dimensional sphere.Research supported in part by PSC-CUNY Research Award 32Research supported in part by NSF under grants DMS–9972300 and DMS–9729992 through IAS     

A small molecule that induces assembly of a four way DNA junction at low temperature

Small molecules that induce the formation of higher order DNA structures have potential therapeutic and nanotechnology applications. Screening of a click library has identified the first compound to induce the formation of a Holliday junction structure at room temperature without the need for a high temperature annealing step.     

Spatial distributions of carbon, nitrogen and sulfur isotope ratios in human hair across the central United States

We present data on the carbon (δ(13)C), nitrogen (δ(15)N) and sulfur (δ(34)S) isotope ratios of human hair collected in the central portions of the USA. These elements are incorporated into hair from the diet and thus provide a record of dietary inputs that may also document geospatial patterns. We detected regional differences in hair δ(34)S values across the USA, with the lowest values in the northern Great Plains and increasing values towards the east, west and south. In contrast, no statistically significant patterns were detected in the spatial variation of human hair δ(13)C and δ(15)N values. Using δ(34)S values and a Geographic Information System approach, we created a map ('sulfur isoscape'). The accuracy of the map was tested using hair samples not included in its generation. We conclude that sulfur isotope analysis may represent a new tool to investigate the movements and/or region-of-origin of humans.