The internal Compton effect

Internal Compton effect, and use of superconducting magnet spectrometer to determine multipolarity assignment

Systematical, experimental investigations on LiMgZ (Z= P, As, Sb) wide band gap semiconductors

This work reports on the experimental investigation of the wide band gap compounds LiMgZ (Z = P, As, Sb), which are promising candidates for opto-electronics and anode materials for Lithium batteries. The compounds crystallize in the cubic (C1_b) MgAgAs structure (space group F-43m). The polycrystalline samples were synthesized by solid state reaction methods. X-ray and neutron diffraction measurements show a homogeneous, single-phased samples. The electronic properties were studied using the direct current (DC) method. Additionally UV-VIS diffuse reflectance spectra were recorded in order to investigate the band gap nature. The measurements show that all compounds exhibit semiconducting behavior with direct band gaps of 1.0 eV to 2.3 eV depending on the Z element. A decrease of the peak widths in the static 7Li nuclear magnetic resonance (NMR) spectra with increasing temperature was observed, which can directly be related to an increase of Li ion mobility.Comment: 8 page

Large Swings in Currencies driven by Fundamentals

Exchange rate returns are fat-tailed distributed. We provide evidence that the apparent non-normality derives from the behavior of macroeconomic fundamentals. Economic and probabilistic arguments are offered for such a relationship. Empirical support is given by testing against normality and through investigating the tail shapes of the fundamentals' distributions. The currently available data sets on floating exchange rates permit a clearer picture than the relatively short spans with macroeconomic data available previously

Physics Potential of Very Intense Conventional Neutrino Beams

The physics potential of high intensity conventional beams is explored. We consider a low energy super beam which could be produced by a proposed new accelerator at CERN, the Super Proton Linac. Water Cherenkov and liquid oil scintillator detectors are studied as possible candidates for a neutrino oscillation experiment which could improve our current knowledge of the atmospheric parameters and measure or severely constrain the parameter connecting the atmospheric and solar realms. It is also shown that a very large water detector could eventually observe leptonic CP violation. The reach of such an experiment to the neutrino mixing parameters would lie in-between the next generation of neutrino experiments (MINOS, OPERA, etc) and a future neutrino factory.Comment: Talk given at the Venice Conference on Neutrino Telescopes, Venice, March, 200

Permeable Surface Corrections for Ffowcs Williams and Hawkings Integrals

The acoustic prediction methodology discussed herein applies an acoustic analogy to calculate the sound generated by sources in an aerodynamic simulation. Sound is propagated from the computed flow field by integrating the Ffowcs Williams and Hawkings equation on a suitable control surface. Previous research suggests that, for some applications, the integration surface must be placed away from the solid surface to incorporate source contributions from within the flow volume. As such, the fluid mechanisms in the input flow field that contribute to the far-field noise are accounted for by their mathematical projection as a distribution of source terms on a permeable surface. The passage of nonacoustic disturbances through such an integration surface can result in significant error in an acoustic calculation. A correction for the error is derived in the frequency domain using a frozen gust assumption. The correction is found to work reasonably well in several test cases where the error is a small fraction of the actual radiated noise. However, satisfactory agreement has not been obtained between noise predictions using the solution from a three-dimensional, detached-eddy simulation of flow over a cylinder

Teff: A New Annual Forage Grass for South Dakota?

Teff (Eragrostis tef Zucc. Trotter) is a major cereal crop in Ethiopia and has been grown in other African countries as a hay crop. Teff is a warm-season, annual grass that has rapid seed germination and seedling development. It also is well adapted to dry climates. These qualities indicate that teff could be used in this region of the U.S. as a supplemental forage during periods when other forage supplies are diminished. In South Dakota, late summer is when forage supplies are typically low. Teff has been marketed recently in South Dakota under the name “Dessie Summer Lovegrass.” This marketing campaign has created interest among producers in the crop’s forage potential. The following information summarizes research conducted at SDSU, over several years, on the forage potential of teff

Banking system stability: A cross-atlantic perspective

Paper prepared for the NBER project on “Risks of Financial Institutions”. We benefited from suggestions and criticism by many participants in the NBER project on “Risks of financial institutions”, in particular by the organizers Mark Carey (also involving Dean Amel and Allen Berger) and Rene Stulz, by our discussant Tony Saunders and by Patrick de Fontnouvelle, Gary Gorton, Andy Lo, Jim O’Brien and Eric Rosengren. Furthermore, we are grateful for comments we received at the 2004 European Finance Association Meetings in Maastricht, in particular by our discussant Marco da Rin and by Christian Upper, at the 2004 Ottobeuren seminar in economics, notably the thoughts of our discussant Ernst Baltensberger, of Friedrich Heinemann and of Gerhard Illing, as well as at seminars of the Max Planck Institute for Research on Collective Goods, the Federal Reserve Bank of St. Louis, the ECB and the University of Frankfurt. Gabe de Bondt and David Marques Ibanez supported us enormously in finding yield spread data, Lieven Baele and Richard Stehle kindly made us aware of pitfalls in Datastream equity data. Very helpful research assistance by Sandrine Corvoisier, Peter Galos and Marco Lo Duca as well as editorial support by Sabine Wiedemann are gratefully acknowledged. Any views expressed only reflect those of the authors and should not be interpreted as the ones of the ECB or the Eurosystem. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research. This paper derives indicators of the severity and structure of banking system risk from asymptotic interdependencies between banks’ equity prices. We use new tools available from multivariate extreme value theory to estimate individual banks’ exposure to each other (“contagion risk”) and to systematic risk. Moreover, by applying structural break tests to those measures we study whether capital markets indicate changes in the importance of systemic risk over time. Using data for the United States and the euro area, we can also compare banking system stability between the two largest economies in the world. Finally, for Europe we assess the relative importance of cross-border bank spillovers as compared to domestic bank spillovers. The results suggest, inter alia, that systemic risk in the US is higher than in the euro area, mainly as cross-border risks are still relatively mild in Europe. On both sides of the Atlantic systemic risk has increased during the 1990s

Searching for hexagonal analogues of the half-metallic half-Heusler XYZ compounds

The XYZ half-Heusler crystal structure can conveniently be described as a tetrahedral zinc blende YZ structure which is stuffed by a slightly ionic X species. This description is well suited to understand the electronic structure of semiconducting 8-electron compounds such as LiAlSi (formulated Li$^+$[AlSi]$^-$) or semiconducting 18-electron compounds such as TiCoSb (formulated Ti$^{4+}$[CoSb]$^{4-}$). The basis for this is that [AlSi]$^-$ (with the same electron count as Si$_2$) and [CoSb]$^{4-}$ (the same electron count as GaSb), are both structurally and electronically, zinc-blende semiconductors. The electronic structure of half-metallic ferromagnets in this structure type can then be described as semiconductors with stuffing magnetic ions which have a local moment: For example, 22 electron MnNiSb can be written Mn$^{3+}$[NiSb]$^{3-}$. The tendency in the 18 electron compound for a semiconducting gap -- believed to arise from strong covalency -- is carried over in MnNiSb to a tendency for a gap in one spin direction. Here we similarly propose the systematic examination of 18-electron hexagonal compounds for semiconducting gaps; these would be the "stuffed wurtzite" analogues of the "stuffed zinc blende" half-Heusler compounds. These semiconductors could then serve as the basis for possibly new families of half-metallic compounds, attained through appropriate replacement of non-magnetic ions by magnetic ones. These semiconductors and semimetals with tunable charge carrier concentrations could also be interesting in the context of magnetoresistive and thermoelectric materials.Comment: 11 pages, 6 figures, of which 4 are colou

Fundamentals and joint currency crises

It is by now well known that Þnancial returns exhibit heavy tails and are thus nonnormally distributed. This implies that extreme market conditions tend to happen more frequently than expected on the basis of the normal distribution, which is used so often in standard asset pricing approaches. From the point of view of international Þnan- cial stability and portfolio diversiÞcation, the strength of asset linkages during crisis periods matters even more, as the linkages determine the stability of the system as a whole. Several papers talk about increased correlation between Þnancial assets or markets during crisis periods. As has been argued before, the use of correlation analysis is not without problems though. Since the correlation concept is just an intermediary step in calculating probabilities, we prefer to deÞne market linkages in terms of conditional probabilities and the expected number of market crashes

Aflatoxin B1 in Corn Silage

Nineteen piles and bunk silos of corn silage were sampled in late fall of 1976 and early spring of 1977. These samples were assayed for aflatoxin Bl, a potent mycotoxin, using a newly developed procedure. No aflatoxin Bl (<5 ug/kg) was detected in any of the 270 samples of corn silage