Wild monodromy and automorphisms of curves

Let $R$ be a complete discrete valuation ring of mixed characteristic $(0,p)$ with field of fractions $K$ containing the $p$-th roots of unity. This paper is concerned with semi-stable models of $p$-cyclic covers of the projective line C \la \PK. We start by providing a new construction of a semi-stable model of $C$ in the case of an equidistant branch locus. If the cover is given by the Kummer equation $Z^p=f(X_0)$ we define what we called the monodromy polynomial ${\mathcal L}(Y)$ of $f(X_0)$; a polynomial with coefficients in $K$. Its zeros are key to obtaining a semi-stable model of $C$. As a corollary we obtain an upper bound for the minimal extension $K'/K$ over which a stable model of the curve $C$ exists. Consider the polynomial ${\cal L}(Y)\prod(Y^p-f(y_i))$ where the $y_i$ range over the zeros of ${\cal L}(Y)$. We show that the splitting field of this polynomial always contains $K'$, and that in some instances the two fields are equal.Comment: The final version of this article will be published in the Duke Mathematical Journal, published by Duke University pres

More Baskets? Renewable Energy and Energy Security

Energy security increasingly becomes an issue in the face of rising worldwide energy demand and dwindling resources. Threats to energy security are seen in political instabilities of resource exporting countries, decreasing reserves, geostrategic and geopolitical factors and the structure of the relevant energy markets in terms of market power, monopolies, cartels and trusts. The European Commission has issued two Green Papers on a strategy for the security of energy supply, supporting competitive international energy market (European Commission, 2000 and 2008). The large infrastructure and gas pipeline development project Nabucco through Turkey, Bulgaria, Romania, Hungary and Austria that has recently been launched is motivated by the assumed increase in energy security.Energy, secruity, reneweable, baskets

Eta electroproduction on nuclei in the nucleon resonance region

We investigate eta electroproduction on nuclei for Q^2=2.4 and 3.6 GeV^2 in the framework of a coupled-channel BUU transport model. We analyze the importance of final state interactions and side feeding and compare with findings drawn from eta photoproduction. It is shown that in contrast to photoproduction the influence of etas stemming from secondary processes becomes important at high Q^2.Comment: 5 pages, 5 figure

Market Based Approaches for Dynamic Spectrum Assignment

Abstract—Much of the technical literature on spectrum sharing has been on developing technologies and systems for non-cooperative) opportunistic use. In this paper, we situate this approach to secondary spectrum use in a broader context, one that includes cooperative approaches to Dynamic Spectrum Access (DSA). In this paper, we introduce readers to this broader approach to DSA by contrasting it with non-cooperative sharing (opportunistic use), surveying relevant literature, and suggesting future directions for researc

Photoreceiver efficiency measurements

The efficiency and other related parameters of Smithsonian Astrophysical Observatory's four laser receivers were measured at the observing stations by oscilloscope photography. If the efficiency is defined as the number of photoelectrons generated by the photomultiplier tube divided by the number of photons entering the aperture of the receiver, its measured value is about 1% for the laser wavelength of 694 nm. This value is consistent with the efficiency computed from the specified characteristics of the photoreceiver's optical components

Equity and Aggregation in Environmental Valuation

Environmental valuation studies aim at the assessment of the social benefits or the social costs caused by some change in environmental quality (in the broadest sense). The most popular field of application of environmental valuation studies is project appraisal where the benefits arising from some environmental project (measured in terms of people's willingness to pay for that project) are assessed and confronted with the costs of the project or with the benefits from some alternative project if a choice has to be made between different projects. A closer look at the results of empirical valuation studies shows that in many surveys a negative correlation between the number auf household members and the willingness to pay (WTP) stated by a household for a project can be observed. These results are rather puzzling because in larger households more people are going to benefit from an environmental improvement than in small households. A plausible explanation for these results is that household budgets are tighter for large households than for smaller households with the same household income. Therefore, large households must state a smaller WTP for a project than smaller households with the same income and the same preferences. This might have consequences for the allocation of public funds in all cases where the realization of a specific environmental project depends on the absolute value of the aggregate social benefits it generates. In order to calculate the social benefits typically the WTPs of the different households affected by that project are added up. In this aggregation process the members of larger households have a lower weight and, therefore, their WTP has a smaller impact on the decision if a certain project is realized or not. The reason for this violation of the principle of horizontal equity is that for the computation of the social benefits not individual but household WTPs are aggregated. In this paper we suggest to use household equivalence scales for the evaluation of WTP data in order to reduce this discrimination of the members of large families. We demonstrate the effects of equivalence scales on the results of environmental valuation surveys using an empirical study carried out in Eastern Germany.contingent valuation; Environmental Valuation; Equity