Summary flow-of-funds accounts 1950-55

Flow of funds

Acid-base properties of purine residues and the effect of metal ions: Quantification of rare nucleobase tautomers

The macro acidity constants valid for aqueous solutions of several adenine, guanine,and hypoxanthine derivatives are summarized. It is shown how the application of the corresponding constants, e.g., for 7,9-dimethyladenine, allows a quantification of the intrinsic acidic properties of the (N1)H0/+ and (N7)H+ sites via micro acidity constants, and how to use this information for the calculation of the tautomeric ratios regarding the monoprotonated species, that is, N7-N1*H versus H*N7-N1, meaning that in one isomer H+ is at the N1 site and in the other at N7. It is further shown that different metal ions coordinated to a given site, e.g., N7, lead to a different extent of acidification, e.g., at (N1)H; the effect decreases in the series Cu2+>Ni2+>Pt2+ ~Pd2+. Moreover, the application of micro acidity constants proves that the acidifications are reciprocal and identical. This means, Pt2+ coordinated to (N1)-/0 sites in guanine, hypoxanthine, or adenine residues acidifies the (N7)H+ unit to the same extent as (N7)-coordinated Pt 2+ acidifies the (N1)H0/+ site. In other words, an apparently increased basicity of N7 upon Pt2+ coordination at (N1)-/0 sites disappears if the micro acidity constants of the appropriate isocharged tautomers of the ligand are properly taken into account. There is also evidence that proton-proton interactions are more pronounced than divalent metal ion-proton interactions, and that these in turn are possibly larger than divalent metal ion-metal ion interactions. The indicated quantifications of the acid-base properties are meaningful for nucleic acids including the formation of certain nucleobase tautomers in low concentrations, which could give rise to mutation

Conceptualising uncertainty in environmental decision-making: The example of the EU Water Framework Directive

The question of how to deal with uncertainty in environmental decision-making is cur-rently attracting considerable attention on the part of scientists as well as of politicians and those involved in government administration. The existence of uncertainty becomes particularly apparent in the field of environmental policy because environmental prob-lems are regarded as highly complex and long-term and because far-reaching changes have to be taken into account; moreover, the knowledge available to practitioners and policy makers alike is often fragmentary and not systemised. One key issue arising from this is the challenge to develop scientific decision support methods that are capable of dealing with uncertainty in a systematic and differentiated way, integrating scientific and practical knowledge. This paper introduces a conceptual framework for perceiving and describing uncertainty in environmental decision-making. It is argued that perceiv-ing and describing uncertainty is an important prerequisite for deciding and acting under uncertainty. The conceptual framework consists of a general definition of uncertainty along with five complementary perspectives on the phenomenon, each highlighting one specific aspect of it. By using the conceptual framework, decision-makers are able to re-flect on their knowledge base with regard to its completeness and reliability and to gain a broad picture of uncertainty from various standpoints. The theoretical ideas presented here are based on two empirical studies looking at how uncertainty is dealt with in the implementation process of the EU Water Framework Directive (WFD). The rather ab-stract differentiations are illustrated by a number of examples in the form of interview statements and excerpts from the WFD and the WFD guidance documents Impress, Wateco und Proclan. --uncertainty,probability,lack of knowledge,pure ignorance,environ-mental decision-making,EU Water Framework Directive (WFD)

Adenosine 5'-triphosphate (ATP4-): Aspects of the coordination chemistry of a multitalented biological substrate

Firstly, the self-stacking properties of ATP4- and the effects of metal ions and protons on these properties are described. Some examples involving macrochelate formation between phosphate-coordinated metal ions (M2+) and N7 of the adenine residue in MATP2- are discussed, and this is followed by considerations on mixed ligand complexes consisting of ATP4-, M2+, and amino acid anions with side chains that allow either aromatic-ring stacking or hydrophobic interactions with the adenine moiety; this gives rise to selectivity. Next, the properties of diphosphorylated 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA2-; Adefovir), i.e., of PMEApp4-, are compared with those of (2'-deoxy)ATP4- with regard to their metal ion-binding qualities, and in this way it can be explained why PMEApp2- is initially an excellent substrate for nucleic acid polymerases. Of course, after incorporation of the PMEA residue into the growing nucleic acid chain, this is terminated and this is how PMEA exerts its antiviral properties [its bis(pivaloyloxymethyl)ester, Adefovir dipivoxil, was recently approved for use in hepatitis B therapy]. Finally, the change in free energy connected with (macro)chelate formation or intramolecular stacking interactions and the effect of a reduced dielectric constant of the solvent on the stability of complexes and their structures in solution is considere

Wissensorganisation, Topic Maps und Ontology Engineering: Die Verbindung bewährter Begriffsstrukturen mit aktueller XML-Technologie

Wie können begriffliche Strukturen an Topic Maps angebunden werden? Allgemeiner: Wie kann die Wissensorganisation dazu beitragen, dass im Semantic Web eine begriffsbasierte Infrastruktur verfügbar ist? Dieser Frage hat sich die Wissensorganisation bislang noch nicht wirklich angenommen. Insgesamt ist die Berührung zwischen semantischen Wissenstechnologien und wissensorganisatorischen Fragestellungen noch sehr gering, obwohl Begriffsstrukturen, Ontologien und Topic Maps grundsätzlich gut zusammenpassen und ihre gemeinsame Betrachtung Erkenntnisse für zentrale wissensorganisatorische Fragestellungen wie z.B. semantische Interoperabilität und semantisches Retrieval erwarten lässt. Daher motiviert und skizziert dieser Beitrag die Grundidee, nach der es möglich sein müsste, eine Sprache zur Darstellung von Begriffsstrukturen in der Wissensorganisation geeignet mit Topic Maps zu verbinden. Eine genauere Untersuchung und Implementation stehen allerdings weiterhin aus. Speziell wird vermutet, dass sich der Concepto zugrunde liegende Formalismus CLF (Concept Language Formalism) mit Topic Maps vorteilhaft abbilden lässt. Damit können Begriffs- und Themennetze realisiert werden, die auf expliziten Begriffssystemen beruhen. Seitens der Wissensorganisation besteht die Notwendigkeit, sich mit aktuellen Entwicklungen auf dem Gebiet des Semantic Web und Ontology Engineering vertraut zu machen, aber auch die eigene Kompetenz stärker aktiv in diese Gebiete einzubringen. Damit dies geschehen kann, führt dieser Beitrag zum besseren Verständnis zunächst aus Sicht der Wissensorganisation knapp in Ontologien und Topic Maps ein und diskutiert wichtige Überschneidungsbereiche

Comments on spin operators and spin-polarization states of 2+1 fermions

In this brief article we discuss spin polarization operators and spin polarization states of 2+1 massive Dirac fermions and find a convenient representation by the help of 4-spinors for their description. We stress that in particular the use of such a representation allows us to introduce the conserved covariant spin operator in the 2+1 field theory. Another advantage of this representation is related to the pseudoclassical limit of the theory. Indeed, quantization of the pseudoclassical model of a spinning particle in 2+1 dimensions leads to the 4-spinor representation as the adequate realization of the operator algebra, where the corresponding operator of a first-class constraint, which cannot be gauged out by imposing the gauge condition, is just the covariant operator previously introduced in the quantum theory.Comment: 6 page

Affordability of water supply in Mongolia: Empirical lessons for measuring affordability

Affordability of water services is a pressing water policy issue for both the developed and in particular the developing world. Despite its well-known theoretical shortcomings affordability analysis for water supply is up to now widely based on the ratio of a household's water expenditure and income (CAR). However in the housing sector alternative concepts of measuring affordability have been developed among them the potential affordability approach (PAA) and the residual income approach (RIA). Against this background the article compares three prominent affordability measures (CAR, PAA, RIA) on the basis of an empirical case study of a ger i.e. low income area in the Mongolian city of Darkhan using household data from a survey conducted in 2009. Thus we gain insight into both the water-related affordability situation of people in Mongolia checking the World Bank's thesis of missing affordability problems in this country as well as the comparative functionality of different affordability measures. Additionally, institutional as well as access-driven problems of water supply are introduced into the analysis. It is shown that affordability problems quite occur for considerable parts of the households but have to be distinguished depending on the economic causation: We argue that none of the regarded measures gives a satisfyingly contoured notion of affordability properly distinguished from the adjacent problems of poverty and access. A mere CAR analysis does not provide sound recommendations for water policy at all. In particular, problems of access entailing non-pecuniary costs of water provision have to be taken into account and might explain both problems of underconsumption and given CAR-affordability at the same time

Divalent metal ions tune the self-splicing reaction of the yeast mitochondrial group II intron Sc .ai5γ

Group II introns are large ribozymes, consisting of six functionally distinct domains that assemble in the presence of Mg2+ to the active structure catalyzing a variety of reactions. The first step of intron splicing is well characterized by a Michaelis-Menten-type cleavage reaction using a two-piece group II intron: the substrate RNA, the 5′-exon covalently linked to domains 1, 2, and 3, is cleaved upon addition of domain 5 acting as a catalyst. Here we investigate the effect of Ca2+, Mn2+, Ni2+, Zn2+, Cd2+, Pb2+, and [Co(NH3)6]3+ on the first step of splicing of the Saccharomyces cerevisiae mitochondrial group II intron Sc.ai5γ. We find that this group II intron is very sensitive to the presence of divalent metal ions other than Mg2+. For example, the presence of only 5% Ca2+ relative to Mg2+ results in a decrease in the maximal turnover rate k cat by 50%. Ca2+ thereby has a twofold effect: this metal ion interferes initially with folding, but then also competes directly with Mg2+ in the folded state, the latter being indicative of at least one specific Ca2+ binding pocket interfering directly with catalysis. Similar results are obtained with Mn2+, Cd2+, and [Co(NH3)6]3+. Ni2+ is a much more powerful inhibitor and the presence of either Zn2+ or Pb2+ leads to rapid degradation of the RNA. These results show a surprising sensitivity of such a large multidomain RNA on trace amounts of cations other than Mg2+ and raises the question of biological relevance at least in the case of Ca2