The vacuum preserving Lie algebra of a classical W-algebra

We simplify and generalize an argument due to Bowcock and Watts showing that one can associate a finite Lie algebra (the `classical vacuum preserving algebra') containing the M\"obius $sl(2)$ subalgebra to any classical \W-algebra. Our construction is based on a kinematical analysis of the Poisson brackets of quasi-primary fields. In the case of the \W_\S^\G-algebra constructed through the Drinfeld-Sokolov reduction based on an arbitrary $sl(2)$ subalgebra $\S$ of a simple Lie algebra \G, we exhibit a natural isomorphism between this finite Lie algebra and \G whereby the M\"obius $sl(2)$ is identified with $\S$.Comment: 11 pages, BONN-HE-93-25, DIAS-STP-93-13. Some typos had been removed, no change in formula

Involutions and the Gelfand character

The Gelfand representation of $\mathcal{S}_n$ is the multiplicity-free direct sum of the irreducible representations of $\mathcal{S}_n$. In this paper, we use a result of Adin, Postnikov, and Roichman to find a recursive generating function for the Gelfand character. In order to find this generating function, we investigate descents of so-called $\lambda$-unimodal involutions

Numerical simulation tests with light dynamical quarks

Two degenerate flavours of quarks are simulated with small masses down to about one fifth of the strange quark mass by using the two-step multi-boson (TSMB) algorithm. The lattice size is 8^3 x 16 with lattice spacing about 0.27fm which is not far from the N_t=4 thermodynamical cross-over line. Autocorrelations of different physical quantities are estimated as a function of the quark mass. The eigenvalue spectra of the Wilson-Dirac operator are investigated.Comment: 14 pages, 7 figures, uses svjour.cls; mistake in the autocorrelation of the pion mass corrected, version accepted for publication on Eur. Phys. J.

Remote determination of auroral energy characteristics during substorm activity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94740/1/grl10101.pd

Status Report on Education in the Economics of Animal Health: Results from a European Survey

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Photometric monitoring of the doubly imaged quasar UM673: possible evidence for chromatic microlensing

We present the results of two-band CCD photometric monitoring of the gravitationally lensed quasar Q 0142-100 (UM 673).The data, obtained at ESO-La Silla with the 1.54 m Danish telescope in the Gunn i-band (October 1998 - September 1999) and in the Johnson V-band (October 1998 to December 2001), were analyzed using three different photometric methods. The light-curves obtained with all methods show variations, with a peak-to-peak amplitude of 0.14 magnitude in $V$. Although it was not possible to measure the time delay between the two lensed QSO images, the brighter component displays possible evidence for microlensing: it becomes bluer as it gets brighter, as expected under the assumption of differential magnification of a quasar accretion diskComment: Accepted for publication in Astronomy & Astrophysics; 8 pages, 7 figure

The Assembly Factor Pet117 Couples Heme a Synthase Activity to Cytochrome Oxidase Assembly

Heme a is an essential metalloporphyrin cofactor of the mitochondrial respiratory enzyme cytochrome c oxidase (CcO). Its synthesis from heme b requires several enzymes, including the evolutionarily conserved heme a synthase (Cox15). Oligomerization of Cox15 appears to be important for the process of heme a biosynthesis and transfer to maturing CcO. However, the details of this process remain elusive, and the roles of any additional CcO assembly factors that may be involved remain unclear. Here we report the systematic analysis of one such uncharacterized assembly factor, Pet117, and demonstrate in Saccharomyces cerevisiae that this evolutionarily conserved protein is necessary for Cox15 oligomerization and function. Pet117 is shown to reside in the mitochondrial matrix, where it is associated with the inner membrane. Pet117 functions at the later maturation stages of the core CcO subunit Cox1 that precede Cox1 hemylation. Pet117 also physically interacts with Cox15 and specifically mediates the stability of Cox15 oligomeric complexes. This Cox15-Pet117 interaction observed by co-immunoprecipitation persists in the absence of heme a synthase activity, is dependent upon Cox1 synthesis and early maturation steps, and is further dependent upon the presence of the matrix-exposed, unstructured linker region of Cox15 needed for Cox15 oligomerization, suggesting that this region mediates the interaction or that the interaction is lost when Cox15 is unable to oligomerize. Based on these findings, it was concluded that Pet117 mediates coupling of heme a synthesis to the CcO assembly process in eukaryotes

A new measure for cosmic shear

We consider here a new statistical measure for cosmic shear, the aperture mass Map, which is defined as a spatially filtered projected density field and which can be measured directly from the image distortions of high-redshift galaxies. By selecting an appropriate spatial filter function, the dispersion of the aperture mass is a convolution of the power spectrum of the projected density field with a narrow kernel, so that provides a well localized estimate of the power spectrum at wavenumbers s~5/theta. We calculate for various cosmological models, using the fully non-linear power spectrum of the cosmic density fluctuations. The non-linear evolution yields a significant increase of relative to the linear growth on scales below ~0.5 degree. The third-order moment of Map can be used to define a skewness, which is a measure of the non-Gaussianity of the density field. We present the first calculation of the skewness of the shear in the frame of quasi-linear theory of structure growth. We show that it yields a sensitive measure of the cosmological model; in particular, it is independent of the normalization of the power spectrum. Several practical estimates for are constructed and their dispersions calculated. We show that one sq.deg. of a high-quality image is sufficient to detect the cosmic shear with the Map-statistics on scales below ~10 arcmin, and to estimate its amplitude with an accuracy of ~30% on scales below ~5 arcmin. (abbreviated)Comment: 34 pages, plain TeX, including 9 figures, submitted to MNRA