Dimensional Reduction applied to QCD at three loops

Dimensional Reduction is applied to \qcd{} in order to compute various renormalization constants in the \drbar{} scheme at higher orders in perturbation theory. In particular, the $\beta$ function and the anomalous dimension of the quark masses are derived to three-loop order. Special emphasis is put on the proper treatment of the so-called $\epsilon$-scalars and the additional couplings which have to be considered.Comment: 13 pages, minor changes, references adde

Phylogenetic diversity of insecticolous fusaria inferred from multilocus DNA sequence data and their molecular identification via FUSARIUM-ID and Fusarium MLST

We constructed several multilocus DNA sequence datasets to assess the phylogenetic diversity of insecticolous fusaria, especially focusing on those housed at the Agricultural Research Service Collection of Entomopathogenic Fungi (ARSEF), and to aid molecular identifications of unknowns via the FUSARIUM-ID and Fusarium MLST online databases and analysis packages. Analyses of a 190-taxon, two-locus dataset, which included 159 isolates from insects, indicated that: (i) insect-associated fusaria were nested within 10 species complexes spanning the phylogenetic breadth of Fusarium, (ii) novel, putatively unnamed insecticolous species were nested within 8/10 species complexes and (iii) Latin binomials could be applied with confidence to only 18/58 phylogenetically distinct fusaria associated with pest insects. Phylogenetic analyses of an 82-taxon, three-locus dataset nearly fully resolved evolutionary relationships among the 10 clades containing insecticolous fusaria. Multilocus typing of isolates within four species complexes identified surprisingly high genetic diversity in that 63/65 of the fusaria typed represented newly discovered haplotypes. The DNA sequence data, together with corrected ABI sequence chromatograms and alignments, have been uploaded to the following websites dedicated to identifying fusaria: FUSARIUM-ID (http://isolate.fusariumdb.org) a

The electroclinic effect and modulated phases in smectic liquid crystals

We explore the possibility that the large electroclinic effect observed in ferroelectric liquid crystals arises from the presence of an ordered array of disclination lines and walls. If the spacing of these defects is in the subvisible range, this modulated phase would be similar macroscopically to a smectic A phase. The application of an electric field distorts the array, producing a large polarization, and hence a large electroclinic effect. We show that with suitable elastic parameters and sufficiently large chirality, the modulated phase is favored over the smectic A and helically twisted smectic C* phases. We propose various experimental tests of this scenario.Comment: 9 pages, 7 figures; new version includes dipolar interactions and bend-twist couplin

Amino Acids as biomarkers in the SOD1G93A mouse model of ALS

AbstractThe development of therapies for Amyotrophic Lateral Sclerosis (ALS) has been hindered by the lack of biomarkers for both identifying early disease and for monitoring the effectiveness of drugs. The identification of ALS biomarkers in presymptomatic individuals might also provide clues to the earliest biochemical correlates of the disease. Previous attempts to use plasma metabolites as biomarkers have led to contradictory results, presumably because of heterogeneity in both the underlying genetics and the disease stage in the clinical population. To eliminate these two sources of heterogeneity we have characterized plasma amino acids and other metabolites in the SOD1G93A transgenic mouse model for ALS. Presymptomatic SOD1G93A mice have significant differences in concentrations of several plasma metabolites compared to wild type animals, most notably in the concentrations of aspartate, cystine/cysteine, and phosphoethanolamine, and in changes indicative of methylation defects. There are significant changes in amino acid compositions between 50 and 70days of age in both the SOD1G93A and wild type mice, and several of the age-related and disease-related differences in metabolite concentration were also gender-specific. Many of the SOD1G93A-related differences could be altered by treatment of mice with methionine sulfoximine, which extends the lifespan of this mouse, inhibits glutamine synthetase, and modifies brain methylation reactions. These studies show that assaying plasma metabolites can effectively distinguish transgenic mice from wild type, suggesting that one or more plasma metabolites might be useful biomarkers for the disease in humans, especially if genetic and longitudinal analysis is used to reduce population heterogeneity

Production of a pseudo-scalar Higgs boson at hadron colliders at next-to-next-to leading order

The production cross section for pseudo-scalar Higgs bosons at hadron colliders is computed at next-to-next-to-leading order (NNLO) in QCD. The pseudo-scalar Higgs is assumed to couple only to top quarks. The NNLO effects are evaluated using an effective lagrangian where the top quarks are integrated out. The NNLO corrections are similar in size to those found for scalar Higgs boson production.Comment: 20 pages, 6 figures, JHEP style, Minor changes, Journal reference adde

Breakage characteristics of granulated food products for prediction of attrition during lean-phase pneumatic conveying

Pneumatic conveying is utilised in a variety of industries to convey food products exhibiting diverse handling characteristics. Attrition of particles caused by this conveying process can result in a number of undesirable outcomes such as loss in product quality or issues in subsequent handling processes. The ability to predict the breakage behaviour of particulate materials is desirable in both new system design and resolving issues in existing plants. This work considers two different particulate materials (Salt and Golden Breadcrumbs) across a range of particle sizes, and quantifies their breakage behaviour under varying impact conditions. Narrow size fractions of each material was degraded; material retained on 250 µm and 355 µm sieves for salt, and 500µm, 710µm and 1000 µm sieves for Golden Breadcrumbs. Velocity was found to be the most influential factor with respect to particle attrition. The results from the narrow size fraction tests were superimposed to form a simulated full size distribution breakage behaviour, which was then compared to the experimentally determined behaviour. A good agreement was found, however the proportion of material predicted for size fractions smaller than 355 µm for Golden Breadcrumbs and 180 µm for Salt was under-predicted. Recommendations for increasing accuracy of the prediction method are given

Four-loop beta function and mass anomalous dimension in Dimensional Reduction

Within the framework of QCD we compute renormalization constants for the strong coupling and the quark masses to four-loop order. We apply the DR-bar scheme and put special emphasis on the additional couplings which have to be taken into account. This concerns the epsilon-scalar--quark Yukawa coupling as well as the vertex containing four epsilon-scalars. For a supersymmetric Yang Mills theory, we find, in contrast to a previous claim, that the evanescent Yukawa coupling equals the strong coupling constant through three loops as required by supersymmetry.Comment: 15 pages, fixed typo in Eq. (18

Magnetized gas in the smith high velocity cloud

We report the first detection of magnetic fields associated with the Smith High Velocity Cloud. We use a catalog of Faraday rotation measures toward extragalactic radio sources behind the Smith Cloud, new H I observations from the Robert C. Byrd Green Bank Telescope, and a spectroscopic map of Hα from the Wisconsin H-Alpha Mapper Northern Sky Survey. There are enhancements in rotation measure (RM) of =100 rad m-2 which are generally well correlated with decelerated Hα emission. We estimate a lower limit on the line-of-sight component of the field of =8 μG along a decelerated filament; this is a lower limit due to our assumptions about the geometry. No RM excess is evident in sightlines dominated by H I or Hα at the velocity of the Smith Cloud. The smooth Hα morphology of the emission at the Smith Cloud velocity suggests photoionization by the Galactic ionizing radiation field as the dominant ionization mechanism, while the filamentary morphology and high (=1 Rayleigh) Hα intensity of the lower-velocity magnetized ionized gas suggests an ionization process associated with shocks due to interaction with the Galactic interstellar medium. The presence of the magnetic field may contribute to the survival of high velocity clouds like the Smith Cloud as they move from the Galactic halo to the disk. We expect these data to provide a test for magnetohydrodynamic simulations of infalling gas

Hubbard model versus t-J model: The one-particle spectrum

The origin of the apparent discrepancies between the one-particle spectra of the Hubbard and t-J models is revealed: Wavefunction corrections, in addition to the three-site terms, should supplement the bare t-J. In this way a quantitative agreement between the two models is obtained, even for the intermediate-$U$ values appropriate for the high-Tc cuprate superconductors. Numerical results for clusters of up to 20 sites are presented. The momentum dependence of the observed intensities in the photoemission spectra of Sr2CuO2Cl2 are well described by this complete strong-coupling approach.Comment: 4 two-column RevTeX pages, including 4 Postscript figures. Uses epsf. Accepted for publication in Physical Review B, Rapid Communicatio

Geochronology and structure of the eastern margin of the Tanzania Craton east of Dodoma

The precise position, nature and U-Pb zircon geochronology of the eastern margin of the Tanzania Craton has been studied in the Mpwapwa area, some 60 km east of Dodoma, central Tanzania, in a number of field transects over a ca. 45 km strike length of the craton margin. The rocks to the east of the Tanzania Craton in this area either belong to the Palaeoproterozoic Usagaran belt, or the “Western Granulite” terrane of the Neoproterozoic East African Orogen, according to different authors. The eastern part of the craton is underlain by typical Neoarchaean migmatitic grey granodioritic orthogneisses dated by ICP-MS at 2674 ± 73 Ma. There is a gradual increase in strain eastwards in these rocks, culminating in a 1 to 2 km wide, locally imbricated, ductile thrust/shear zone with mylonites indicating an oblique top-to-the-NW, transpressional sense of movement. East of the craton-edge shear zone, a series of high-grade supracrustal rocks are termed the “Mpwapwa Group”, in view of uncertain age and regional lithostratigraphic correlations. There is an apparent east-west lithological zonation of Mpwapwa Group parallel to the craton margin shear zone. In the west, immediately adjacent to the craton, the group consists of typical “shelf facies” metasediments (marbles, calc-silicates, quartzites etc.). U-Pb dating of detrital zircons from two Mpwapwa Group quartzite samples from this marginal zone contain only Archaean detritus, constraining their maximum depositional age to > ca. 2.6 Ga and suggesting that the group is Neoarchaean in age. The shelf rocks pass eastwards into garnet and kyanite-bearing semi-pelitic gneisses interlayered with bimodal mafic-felsic gneisses, where the mafic amphibolite gneisses may represent meta-basalts and the felsic rocks may have meta-rhyolite, -granite or –psammite protoliths. Massive garnet-clinopyroxene amphibolite layers in the Mpwapwa Group gneisses may have been intrusive mafic sills and possibly correlate with the Palaeoproterozoic Isimani Suite, which outcrops south of the study area and includes 2 Ga eclogites. Zircons from a quartzo-feldsapthic gneiss sample from the bimodal gneisses were dated and showed it to be a probable Neoarchaean rock which underwent metamorphism during the Palaeoproterozoic Usagaran event at ca. 1950 Ma. This event was broadly coeval with subduction, closure of an ocean basin and eclogite formation further south and led to the initial juxtaposition of the two Archaean blocks. The metamorphism probably dates the tectonic event when the Archaean Mpwapwa Group rocks were juxtaposed against the orthogneissic Tanzania Craton. The Mpwapwa Group was intruded by weakly foliated biotite granite at 1871 ± 35 Ma. Zircons in the granite have metamorphic rims dated between 550 and 650 Ma that grew during the East African orogenic event