A model for parton distributions in hadrons

The non-perturbative parton distributions in hadrons are derived from simple physical arguments resulting in an analytical expression for the valence parton distributions. The sea partons arise mainly from pions in hadronic fluctuations. The model gives new insights and a good description of structure function data.Comment: 3 pages, 4 figures, LaTeX. Contribution to DIS 99 worksho

Dynamical QCD Predictions for Ultrahigh Energy Neutrino Cross Sections

Neutrino-nucleon total cross sections for neutrino energies up to ultrahigh energies (UHE), E_\nu=10^12 GeV, are evaluated within the framework of the dynamical (radiative) parton model. The expected uncertainties of these predictions do not exceed the level of about 20 % at the highest energies where contributions of parton distributions in the yet unmeasured region around x\simeq 10^-8 to 10^-9 are non-negligible. This is far more accurate than estimated uncertainties of about 2^+-1 due to ad hoc extrapolations of parton distributions to x<10^-5 required for calculating UHE cosmic neutrino event rates.Comment: 16 pages, LaTeX, 4 figures, uses epsfig and amssymb styl

On the analytical approximation to the GLAP evolution at small x and moderate Q^2

Comparing the numerically evaluated solution to the leading order GLAP equations with its analytical small-x approximation we have found that in the domain covered by a large fraction of the HERA data the analytic approximation has to be augmented by the formally non-leading term which has been usually neglected. The corrected formula fits the data much better and provides a natural explanation of some of the deviations from the $\sigma$ scaling observed in the HERA kinematical range.Comment: LaTeX, 13 pages including 6 figures, figure 5 replaced, to appear in Phys. Lett.

Hard scattering factorization and light cone hamiltonian approach to diffractive processes

We describe diffractive deeply inelastic scattering in terms of diffractive parton distributions. We investigate these distributions in a hamiltonian formulation that emphasizes the spacetime picture of diffraction scattering. For hadronic systems with small transverse size, diffraction occurs predominantly at short distances and the diffractive parton distributions can be studied by perturbative methods. For realistic, large-size systems we discuss the possibility that diffractive parton distributions are controlled essentially by semihard physics at a scale of nonperturbative origin of the order of a GeV. We find that this possibility accounts for two important qualitative aspects of the diffractive data from HERA: the flat behavior in beta and the delay in the fall-off with Q^2.Comment: 51 pages, 16 figure

Using Computational Text Mining to Understand Public Priorities for Disability Policy Towards Children in Canadian National Consultations

Identifying policy preferences from public consultations presents a challenge to national and local governments. Computational text mining approaches provide a useful strategy for analyzing the large-scale textual data emerging from these policy processes. In this study, we developed an inductive and deductive text mining approach to understand disability-related policy priorities. This approach is applied to data from the nationwide disability policy consultation conducted in 2016 by the Government of Canada. This process included 18 town hall meetings, 9 thematic roundtables, and online submissions from 92 stakeholders. Transcripts of these consultations were made available to researchers. Three broad research questions were asked of this data, focused on key themes; differences by city size and type of consultation; and impact of two global policy frameworks. The study identified a number of key themes and saw differences by city size. The study identified content related to both the CRPD and CRC

Bounds on QCD Instantons from HERA

Signals for processes induced by QCD instantons are searched for in HERA data on the hadronic final state in deep-inelastic scattering. The maximally allowed fraction of instanton induced events is found at 95% confidence level to be on the percent level in the kinematic domain 0.0001<x<0.01 and 5 < Q-squared < 100 GeV-squared. The most stringent limits are obtained from the multiplicity distributions.Comment: 14 pages, latex, 9 figures as ps/ep

Carbon dioxide dynamics from sediment, sediment-water interface and overlying water in the aquaculture shrimp ponds in subtropical estuaries, southeast China

Aquaculture ponds can emit a large amount carbon dioxide (CO2), with the consequence of exacerbating global climate change. Many studies about CO2 dynamics across the water-air interface, but CO2 in sediment and overlying water received relative less attention. In this study, CO2 concentration in sediment porewater, the diffusive CO2 fluxes across the sediment-water interface (SWI), and the CO2 production rates in the overlying water (CO2_WP) were determined in the shrimp ponds in the Min River Estuary (MRE) and Jiulong River Estuary (JRE), southeast China, to analyze the dynamics of CO2 among different growth stages of shrimps. Our results showed large variations in porewater CO2 concentrations, CO2 diffusive fluxes and CO2_WP rates among different growth stages, with markedly larger values in the middle stage of shrimp growth. The temporal variation of CO2 in both estuarine ponds followed closely the seasonal change of temperature. The internal CO2 production (CO2_IP) in these ponds was dominated by sediments. A significantly larger mean porewater CO2 concentrations, diffusive fluxes and production rate were observed in the MRE ponds than those in the JRE ponds, which could be attributed to the lower water salinity and a larger source of carbon substrates in the former estuary. Considering a total surface area of 6.63 × 103 km2 across the mariculture ponds in subtropical estuaries, it is estimated conservatively that approximately 100 Gigagram (Gg) of dissolved organic carbon and 190 Gg of dissolved inorganic carbon were transported annually from the mariculture ponds into China's coastal areas. Because of the substantial supply of dissolved carbon, the adjacent coastal waters receiving effluent discharge from the mariculture ponds could become “hotspots” of CO2 emissions. Our results highlight the role of aquaculture pond as a major CO2 source in China's coastal areas, and effective actions are needed to alleviate the greenhouse gas (GHG) emissions from these ponds

The proton and the photon, who is probing whom in electroproduction?

The latest results on the structure of the proton and the photon as seen at HERA are reviewed while discussing the question posed in the title of the talk.Comment: 18 pages, including 28 figures. To be published in the proceedings of the 2nd KEK-Tanashi International Symposium on Hadron and Nuclear Physics with Electromagnetic Probes, KEK-Tanashi, Tokyo, Japan, October 25-27, 1999. Typos in eqs (8) and (9) corrected and reference 5 update

Color-Singlet and Color-Octet Contributions to J/ψJ/\psi Photoproduction

I discuss the impact of color-octet contributions and higher-order QCD corrections on the cross section for inelastic $J/\psi$ photoproduction. The theoretical predictions are compared with recent experimental data obtained at HERA.Comment: LaTeX, 10 pages, 6 figures. Talk presented at the Workshops `QED and QCD in Higher Orders', Rheinsberg, Germany, April 21-26 and `Quarkonium Physics', Chicago, USA, June 13-15, 1996; to appear in the proceeding

Statistical Model for the Nucleon Structure Functions

A phenomenological model for the nucleon structure functions is presented. Visualising the nucleon as a cavity filled with parton gas in equilibrium and parametrizing the effects due to the finiteness of the nucleon volume, we obtain a good fit to the data on the structure function $F_2^p$. The model then successfully predicts other unpolarized structure function data.Comment: 11 pages, Latex, 3 ps figures. typographical errors in the values of a and b on page 6, and in the footnote were corrected. No other change