Glueballs and Hybrids (Gluons as Constituents)

After a brief introduction to hybrid and glueball source operators, I summarize recent lattice results for these particles.Comment: 5 pages, contribution to LATTICE-99, corrected glueball mass tabl

Beyond the quark model of hadrons from lattice QCD

Lattice QCD can give direct information on OZI-violating contributions to mesons. Here we explore the contributions that split flavour singlet and non-singlet meson masses. I discuss in detail the spectrum and decays for scalar mesons (ie including glueball effects). I also review the status of hybrid mesons and their decays.Comment: to appear in proceedings of QNP2002, 3 pages, LATEX, 2 ps figure

Assessing the importance of intraspecific variability in dung beetle functional traits

Functional diversity indices are used to facilitate a mechanistic understanding of many theoretical and applied questions in current ecological research. The use of mean trait values in functional indices assumes that traits are robust, in that greater variability exists between than within species. While the assertion of robust traits has been explored in plants, there exists little information on the source and extent of variability in the functional traits of higher trophic level organisms. Here we investigated variability in two functionally relevant dung beetle traits, measured from individuals collected from three primary forest sites containing distinct beetle communities: body mass and back leg length. In doing so we to addressed the following questions: (i) what is the contribution of intra vs. interspecific differences in trait values; (ii) what sample size is needed to provide representative species mean trait values; and (iii) what impact does omission of intraspecific trait information have on the calculation of functional diversity (FD) indices from naturally assembled communities? At the population level, interspecific differences explained the majority of variability in measured traits (between 94% and 96%). In accordance with this, the error associated with calculating FD without inclusion of intraspecific variability was low, less than 20% in all cases. This suggests that complete sampling to capture intraspecific variance in traits is not necessary even when investigating the FD of small and/or naturally formed communities. To gain an accurate estimation of species mean trait values we encourage the measurement of 30-60 individuals and, where possible, these should be taken from specimens collected from the site of study

The confining string and its breaking in QCD

We point out that the world sheet swept by the confining string in presence of dynamical quarks can belong to two different phases, depending on the number of charge species and the quark masses. When it lies in the normal phase (as opposed to the tearing one) the string breaking is invisible in the Wilson loop, while is manifest in operators composed of disjoint sources, as observed in many numerical experiments. We work out an explicit formula for the correlator of Polyakov loops at finite temperature, which is then compared with recent lattice data, both in the quenched case and in presence of dynamical quarks. The analysis in the quenched case shows that the free bosonic string model describes accurately the data for distances larger than ~ 0.75 fm. In the unquenched case we derive predictions on the dependence of the static potential on the temperature which are compatible with the lattice data.Comment: 15 pages, LaTeX with 4 eps figures (included

Finite-size-scaling functions for 3d O(4) and O(2) spin models and QCD

We calculate numerically universal finite-size-scaling functions for the three-dimensional O(4) and O(2) models. The approach of these functions to the infinite-volume scaling functions is studied in detail on the critical and pseudocritical lines. For this purpose we determine the pseudocritical line in two different ways. We find that the asymptotic form of the finite-size-scaling functions is already reached at small values of the scaling variable. A comparison with QCD lattice data for two flavours of staggered fermions shows a similar finite-size behaviour which is compatible with that of the spin models.Comment: 14 pages, 14 Ps-figures, Latex2

The Nucleon Electric Dipole Form Factor From Dimension-Six Time-Reversal Violation

We calculate the electric dipole form factor of the nucleon that arises as a low-energy manifestation of time-reversal violation in quark-gluon interactions of effective dimension 6: the quark electric and chromoelectric dipole moments, and the gluon chromoelectric dipole moment. We use the framework of two-flavor chiral perturbation theory to one loop

``GLUELUMP'' SPECTRUM AND ADJOINT SOURCE POTENTIAL IN LATTICE QCD3_3

We calculate the potential between ``quarks'' which are in the adjoint representation of SU(2) color in the three-dimensional lattice theory. We work in the scaling region of the theory and at large quark separations $R$. We also calculate the masses $M_{Qg}$ of color-singlet bound states formed by coupling an adjoint quark to adjoint glue (``gluelumps''). Good scaling behavior is found for the masses of both magnetic (angular momentum $J=0$) and electric ($J=1$) gluelumps, and the magnetic gluelump is found to be the lowest-lying state. It is naively expected that the potential for adjoint quarks should saturate above a separation $R_{\rm scr}$ where it becomes energetically favorable to produce a pair of gluelumps. We obtain a good estimate of the naive screening distance $R_{\rm scr}$. However we find little evidence of saturation in the potential out to separations $R$ of about twice $R_{\rm scr}$.Comment: 8 pages plus 8 figures in 2 postscript files (uuencoded

Equation of state and Goldstone-mode effects of the three-dimensional O(2) model

We investigate numerically the three-dimensional O(2) model on 8^3-160^3 lattices as a function of the magnetic field H. In the low-temperature phase we verify the H-dependence of the magnetization M induced by Goldstone modes and determine M in the thermodynamic limit both by extrapolation and by chiral perturbation theory. This enables us to calculate the corresponding critical amplitude. At T_c the critical scaling behaviour of the magnetization as a function of H is used to determine another critical amplitude. In both cases we find negative corrections-to-scaling. Our low-temperature results are well described by the perturbative form of the model's magnetic equation of state, with coefficients determined nonperturbatively from our data. The O(2) scaling function for the magnetization is found to have a smaller slope than the one for the O(4) model.Comment: 15 pages, Latex2e, Fig.6b replaced, several comments and two references added, final version for Phys. Lett.

The Application of a Hypothesis-driven Strategy to the Sensitive Detection and Location of Acetylated Lysine Residues

The application of a hypothesis-driven method for the sensitive determination of lysine acetylation sites on enzymatically digested proteins is described. Comparative sensitivity tests were carried out using serial dilution of an acetylated bovine serum albumin (AcBSA) digest to assess the performance of a multiple reaction monitoring (MRM)–based approach as compared to a more conventional precursor scanning (PS) method. Both methods were capable of selectively detecting an acetylated peptide at the low femtomole level when spiked into a background of 500 fmol six-protein tryptic digest. The MRM approach was roughly tenfold more sensitive than precursor scanning with one acetylated peptide detected and sequenced at the level of 2 fmol on-column. The technique was subsequently applied to a gel-derived sample of cytokeratin-8 (CK8) shown to contain acetylated lysine residues by Western blot analysis. The strategy applied herein, termed MRM-initiated detection and sequencing (MIDAS), resulted in the facile identification of novel sites of acetylation on this protein

Estrogens and aspects of prostate disease

Estrogens have long been associated with the processes involved in prostate carcinogenesis, particularly in cancer suppression. However, the synergistic influence of low concentrations of estrogens, together with androgens, in promoting aberrant growth of the gland has also been recognized. As new insights into the complex molecular events implicated in growth regulation of the prostate are revealed, the role of the estrogens has become clearer. The present review considers this role in relation to the pathogenesis of prostate cancer and the potential cancer-repressive influence of the dietary estrogens