ON THE MULTI-PREFERENCE APPROACH TO EVALUATING OPPORTUNITIES

The purpose of the paper is to provide a general framework for analyzing ""preference for opportunities."" Based on two simple axioms a fundamental result due to Kreps is used in order to represent rankings of opportunity sets in terms of multiple preferences. The paper provides several refinements of the basic representation theorem. In particular, a condition of ""closedness under compromise"" is suggested in order to distinguish the flexibility interpretation of the model from normative interpretations which play a crucial role in justifying the intrinsic value of opportunities. Moreover, the paper clarifies the link between the multiple preference approach and the ""choice function"" approach to evaluating opportunities. In particular, it is shown how the well-known Aizerman/Malishevski result on rationalizability of choice functions can be obtained as a corollary from the more general multiple preference representation of a ranking of opportunity sets.

The Antithesis: Challenging the Current Execution of University Thesis via the Exquisite Capriccio and Grand Tour

This thesis challenges the current set of norms, definitions and execution of present university thesis via a speculative extension and practice of the grand tour and travel journal through a montaging of mediums, experiences, methods, and techniques

Quantitative and qualitative biogenic silicon analyses combining modern microscopical and spectroscopical methods

Numerous organisms comprising pro- and eukaryotes are evolutionarily adapted to synthesize siliceous structures (biosilicification). In terrestrial biogeosystems biogenic silicon (BSi) accumulation of phytogenic (BSi synthesized by plants), protistic (diatoms and testate amoeba), microbial (bacteria and fungi) and zoogenic (sponges) origin results in formation of corresponding BSi pools. Accumulation and recycling of BSi in terrestrial ecosystems influence fluxes of dissolved Si from the continents to the oceans, thus act as a filter in the global Si cycle. Although the biogenic control mechanism especially of phytogenic Si pools (phytoliths) has been generally recognized since decades quantitative information on other terrestrial BSi pools is rare. Additionally, information on physicochemical properties of the various siliceous structures are needed to better understand their dissolution kinetics. We used modern microscopical (laser scanning microscopy, LSM; Scanning electron microscopy with coupled energy-dispersive X-ray spectroscopy, SEM-EDX) and spectroscopical (micro-Fourier transform infrared spectroscopy, micro-FTIR) methods for quantitative and qualitative analyses of BSi structures. LSM was used to measure volumes and surface areas of BSi structures and corresponding surface-area-to-volume ratios (A:V ratios) were calculated as an indicator for the resistibility of these siliceous structures against dissolution. Volume measurements were also used for the quantification of BSi pools by multiplication of corresponding volumes with BSi density. SEM-EDX analyses provided information on the elemental composition of different BSi structures and with the help of micro-FTIR we were able to gain specific information about chemical bonding and molecular structures of BSi. These information will help us to understand in detail dissolution kinetics of various siliceous structures, thus their role in Si cycling

Momentum diffusion for coupled atom-cavity oscillators

It is shown that the momentum diffusion of free-space laser cooling has a natural correspondence in optical cavities when the internal state of the atom is treated as a harmonic oscillator. We derive a general expression for the momentum diffusion which is valid for most configurations of interest: The atom or the cavity or both can be probed by lasers, with or without the presence of traps inducing local atomic frequency shifts. It is shown that, albeit the (possibly strong) coupling between atom and cavity, it is sufficient for deriving the momentum diffusion to consider that the atom couples to a mean cavity field, which gives a first contribution, and that the cavity mode couples to a mean atomic dipole, giving a second contribution. Both contributions have an intuitive form and present a clear symmetry. The total diffusion is the sum of these two contributions plus the diffusion originating from the fluctuations of the forces due to the coupling to the vacuum modes other than the cavity mode (the so called spontaneous emission term). Examples are given that help to evaluate the heating rates induced by an optical cavity for experiments operating at low atomic saturation. We also point out intriguing situations where the atom is heated although it cannot scatter light.Comment: More information adde

Equivariant cohomology and analytic descriptions of ring isomorphisms

In this paper we consider a class of connected closed $G$-manifolds with a non-empty finite fixed point set, each $M$ of which is totally non-homologous to zero in $M_G$ (or $G$-equivariantly formal), where $G={\Bbb Z}_2$. With the help of the equivariant index, we give an explicit description of the equivariant cohomology of such a $G$-manifold in terms of algebra, so that we can obtain analytic descriptions of ring isomorphisms among equivariant cohomology rings of such $G$-manifolds, and a necessary and sufficient condition that the equivariant cohomology rings of such two $G$-manifolds are isomorphic. This also leads us to analyze how many there are equivariant cohomology rings up to isomorphism for such $G$-manifolds in 2- and 3-dimensional cases.Comment: 20 pages, updated version with two references adde

Nuclear matrix element for two neutrino double beta decay from 136Xe

The nuclear matrix element for the two neutrino double beta decay (DBD) of 136Xe was evaluated by FSQP (Fermi Surface Quasi Particle model), where experimental GT strengths measured by the charge exchange reaction and those by the beta decay rates were used. The 2 neutrino DBD matrix element is given by the sum of products of the single beta matrix elements via low-lying (Fermi Surface) quasi-particle states in the intermediate nucleus. 136Xe is the semi-magic nucleus with the closed neutron-shell, and the beta + transitions are almost blocked. Thus the 2 neutrino DBD is much suppressed. The evaluated 2 neutrino DBD matrix element is consistent with the observed value.Comment: 7 pages 6 figure

s-wave resonances for the 18F(p, a)15O reaction in novae

The 18F(p,$\alpha$) reaction determines the rate of destruction of 18F in novae. It represents the key nuclear physics uncertainty in modelling the calculated flux of annihilation radiation emitted following the radioactive decay of 18F. The major uncertainties relate to states representing s-wave resonances in the compound system, 19Ne. We report a first study of the 19F(3He, t)19Ne reaction at intermediate energies and forward angles. This reaction has a simple, model-independent, mechanism that we use here to identify states near the proton threshold energy in 19Ne corresponding to $\Delta L=0$ transitions. In particular, we observe a $\Delta L=0$ state at 6.13 MeV which could significantly affect the 18F(p,$\alpha$) astrophysical S-factor at nova burning temperatures