The dependence of dijet production on photon virtuality in ep collisions at HERA

The dependence of dijet production on the virtuality of the exchanged photon, Q^2, has been studied by measuring dijet cross sections in the range 0 < Q^2 < 2000 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb^-1. Dijet cross sections were measured for jets with transverse energy E_T^jet > 7.5 and 6.5 GeV and pseudorapidities in the photon-proton centre-of-mass frame in the range -3 < eta^jet <0. The variable xg^obs, a measure of the photon momentum entering the hard process, was used to enhance the sensitivity of the measurement to the photon structure. The Q^2 dependence of the ratio of low- to high-xg^obs events was measured. Next-to-leading-order QCD predictions were found to generally underestimate the low-xg^obs contribution relative to that at high xg^obs. Monte Carlo models based on leading-logarithmic parton-showers, using a partonic structure for the photon which falls smoothly with increasing Q^2, provide a qualitative description of the data.Comment: 35 pages, 6 eps figures, submitted to Eur.Phys.J.

Beauty photoproduction measured using decays into muons in dijet events in ep collisions at s\sqrt{s}=318 GeV

The photoproduction of beauty quarks in events with two jets and a muon has been measured with the ZEUS detector at HERA using an integrated luminosity of 110 pb$^{- 1}$. The fraction of jets containing b quarks was extracted from the transverse momentum distribution of the muon relative to the closest jet. Differential cross sections for beauty production as a function of the transverse momentum and pseudorapidity of the muon, of the associated jet and of $x_{\gamma}^{jets}$, the fraction of the photon's momentum participating in the hard process, are compared with MC models and QCD predictions made at next-to-leading order. The latter give a good description of the data.Comment: 32 pages, 6 tables, 7 figures Table 6 and Figure 7 revised September 200

An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment

The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e+ and e− beams, together with differential cross-section data on inclusive jet production in e+p scattering and dijet production in γp scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet-production data constrains the gluon and allows an accurate extraction of αs (MZ) at NLO; αs (MZ) = 0.1183 ± 0.0028(exp.) ± 0.0008(model). An additional uncertainty from the choice of scales is estimated as ±0.005. This is the first extraction of αs (MZ) from HERA data alone

Search for Resonance Decays to Lepton+jet at DESY HERA and Limits on Leptoquarks

A search for narrow-width resonances that decay into electron+jet or neutrino+jet has been performed with the ZEUS detector at the DESY ep collider HERA operating at center-of-mass energies of 300 and 318 GeV. An integrated e+p luminosity of 114.8 pb-1 and e-p luminosity of 16.7 pb-1 were used. No evidence for any resonance was found. Limits were derived on the Yukawa coupling λ as a function of the mass of a hypothetical resonance that has arbitrary decay branching ratios into eq or vq. These limits also apply to squarks predicted by R-parity-violating supersymmetry. Limits for the production of leptoquarks described by the Buchmüller-Rückl-Wyler model were also derived for masses up to 400 GeV. For λ = 0.1, leptoquark masses up to 290 GeV are excluded

Can large scintillators be used for solar-axion searches to test the cosmological axion-photon oscillation proposal?

Solar-axion interaction rates in NaI, CsI and Xe scintillators via the axio-electric effect were calculated. A table is presented with photoelectric and axioelectric cross sections, solar-axion fluxes, and the interaction rates from 2.0 to 10.0 keV. The results imply that annual-modulation data of large NaI and CsI arrays, and large Xe scintillation chambers, might be made sensitive enough to probe coupling to photons at levels required to explain axion-photon oscillation phenomena proposed to explain the survival of high-energy photons traveling cosmological distances. The DAMAA/LIBRA data are used to demonstrate the power of the model-independent annual modulation due to the seasonal variation in the earth sun distance.Comment: 7 pages and no figure

Abstract C29: Bladder cancer-associated single nucleotide polymorphisms of vascular endothelial growth factor in 12 human cell lines

Abstract Introduction: Vascular endothelial growth factor (VEGF), critical in angiogenesis, is important for solid tumor growth and metastasis. Three single nucleotide polymorphisms (SNP) in the promoter (rs833052, rs1109324 and rs1547651) and one in the 5′-UTR regions (rs25648) of VEGF have been associated with increased risk for bladder cancer, and one at intron 2 (rs3024994) with decreased risk in a large-scale case-control study. The genotype frequency of the five bladder cancer-associated SNPs among various ethnic groups is similar based on the dbSNP and the SNP500Cancer databases. The objective of this study was to determine the presence of these variants in a panel of 12 human bladder cancer cell lines. Methods: Twelve bladder cancer cell lines, commonly used in urological research and derived from various ethnic groups, were included in the study. Genotypes of the five SNPs were determined for the12 cell lines by direct PCR sequencing. The basal VEGF secretion by these cell lines in culture was measured by ELISA using a microsphere-based array (Millipore) and Luminex® xMAP technology. Results: The SNP genotype frequency was in agreement with that reported in the databases. The only bladder cancer-associated variant (rs833052: C&amp;gt;A) was detected in UM-UC-3, a cell line with many other genetic alterations. The secreted VEGF level in these cell lines as determined by ELISA varied considerably. No correlation between VEGF production and any particular SNP genotype could be established. Conclusions: The reported bladder cancer associated variants in VEGF was detected in only one of the twelve cell lines. Though these SNPs are all located in the regulatory regions, it appears that they have no effect on basal VEGF production in the cultured cells. Considering the low prevalence of these variants reported, the role of these SNPs in VEGF production and bladder cancer remains to be defined. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C29.</jats:p

Acquired myasthenia gravis associated with a non-invasive thymic carcinoma in a dog

An 8 1/2-year-old neutered male Beagle was diagnosed with acquired myasthenia gravis associated with a non-invasive thymic carcinoma. The thymic mass was surgically excised and the dog was treated with pyridostigmine, prednisolone and azathioprine. Serial acetylcholine receptor antibody titres were increased initially but slowly declined to normal values over a period of 24 weeks. Improved exercise tolerance was seen following therapy, however, oesophageal dysfunction persisted. The dog was euthanased 26 weeks after initial presentation due to a complicating illness. A necropsy showed no regrowth or metastasis of the thymic carcinoma