An alternative method to access diverse N,N′-diquaternised-3,3′-biquinoxalinium “biquinoxen” dications

An alternative synthetic route for the design of N,N′-diquaternised-3,3′-biquinoxalinium “biquinoxen” dications is reported, involving oxidative radical coupling of dithionite reduced quinoxaline quaternary salts. Although the reaction is not regioselective, leading to relatively modest yields (up to 32%), the advantages of this new synthetic protocol lie in a simple potentially gram scale synthesis using inexpensive easily accessible reagents with no metal catalysts and no purification steps. Thus whereas the method reported previously to access the N,N′-dimethyl-3,3′-biquinoxalinium, “methylbiquinoxen” precursor gave higher yield than the new method reported here, this new method avoids the limitation of using scarce oxonium reagents. Overall, the new protocol is a robust synthetic strategy which offers new design possibilities

Statistical vs. Identified Lives in Benefit-Cost Analysis

Economic evaluation of projects involving changes in mortality risk conventionally assumes that lives are statistical, i.e., that risks and policy-induced changes in risk are small and similar among a population. In reality, baseline mortality risks and policy-induced changes in risk often differ among individuals although these differences are imperfectly known. We examine the effects of information about heterogeneity of risk on economic evaluation. Although social welfare (defined as aggregate expected utility) is unaffected by information about risk heterogeneity, the economic valuation of changes in risk (the sum of individual compensating or equivalent variations) is sensitive to this information. The effect of information on economic valuation and hence the outcome of a benefit-cost analysis (BCA) depends on: i) whether information is about heterogeneity of the baseline and/or change in risk, ii) whether risk is valued using willingness to pay (WTP) or willingness to accept (WTA) measures, iii) the status quo policy, and iv) whether individuals are risk-averse or risk-neutral in wealth. We show that BCA does not systematically favor identified over statistical lives and suggest some political factors that may explain the apparent public-decision bias toward protecting identified lives.

Nature of excitations of the 5/2 fractional quantum Hall effect

It is shown, with the help of exact diagonalization studies on systems with up to sixteen electrons, in the presence of up to two delta function impurities, that the Pfaffian model is inadequate for the actual quasiholes and quasiparticles of the 5/2 fractional quantum Hall effect. Implications for non-Abelian statistics are discussed.Comment: 4 pages, 2 figure

The Social Value of Mortality Risk Reduction: VSL vs. The Social Welfare Function Approach

We examine how different welfarist frameworks evaluate the social value of mortality risk reduction. These frameworks include classical, distributively unweighted cost–benefit analysis—i.e., the “value per statistical life” (VSL) approach—and various social welfare functions (SWFs). The SWFs are either utilitarian or prioritarian, applied to policy choice under risk in either an “ex post” or “ex ante” manner. We examine the conditions on individual utility and on the SWF under which these frameworks display sensitivity to wealth and to baseline risk. Moreover, we discuss whether these frameworks satisfy related properties that have received some attention in the literature, namely equal value of risk reduction, preference for risk equity, and catastrophe aversion. We show that the particular manner in which VSL ranks risk-reduction measures is not necessarily shared by other welfarist frameworks

A surprising relation between double exchange and Heisenberg model spectra: Application to half-doped manganites

The Zener polarons recently found in half-doped manganites are usually seen as mixed valence entities ruled by a double exchange Hamiltonian involving only correlated electrons of the metals. They can however be considered as ferrimagnetic local units if the holes are localized on the bridging oxygen atoms as implicitely suggested by recent mean-field it ab initio calculations. In the latter case, the physics is ruled by a Heisenberg Hamiltonian involving magnetic oxygen bridges. This paper shows that the spectra resulting from the resolution of both models are analytically identical. This single resulting model spectrum accurately reproduces the spectrum of Zener polarons in Pr0.6Ca0.4MnO3 manganite studied by means of explicitely correlated ab initio calculations. Since the physics supported by each model are different, the analysis of the exact Hamiltonian ground state wave function should a priori enables one to determine the most appropriate model. It will be shown that neither the spectrum nor the wavefunction analysis bring any decisive arguments to settle the question. Such undecidability would probably be encountered in experimental information.Comment: 4 pages, 2 figure

Estimating Monthly GDP In A General Kalman Filter Framework: Evidence From Switzerland

In this paper, we estimate deseasonalized monthly series for Swiss Gross Domestic Product at constant prices of 1990 for the period 1980-1998. They are consistent with the quarterly figures estimated by the Federal Office for Economic Development and Labour and are obtained by including information contained in related series. We present a general approach using the Kalman Filter technique nesting a great variety of interpolation setups. We evaluate competing models and provide a time series that can be used by other researchers.Interpolation, Kalman filter, National accounting.