The feasibility of measuring parton distribution functions of of virtual photons via the jet production at HERA is investigated. Production of jets in ep collisions at HERA offers one of the ways of studying the structure of the virtual photon. Due to the fact that this structure needs time to develop, parton distribution functions (PDF) fi(x, P , Q) of the virtual photon, probed at the hard sc...

The cross section for the diffractive reaction γ∗ + p → cc̄ + p with a real or virtual photon is calculated in the nonperturbative two-gluon exchange model of Landshoff and Nachtmann. Numerical predictions are given for cross sections and spectra at typical HERA values of c.m. energy and photon virtuality. The contribution of charm to the diffractive structure function is evaluated and found to ...

R 2 according to a Poisson process with intensity 1 and let GA be the random graph with vertex set {xi} and edges xixj whenever xi − xj ∈ A. We show that if the area of A is large, then GA almost surely has an infinite component. Moreover, if we fix ε, increase r and let nc = nc(ε) be the area of A when this infinite component appears, then nc → 1 as ε → 0. This is in contrast to the case of a ...

Virtuality is often defined solely as that which lacks or is not material reality, and as such, much of the social order that is uniquely engendered within technologically-mediated realities has been inadequately described. This panel attempts to define virtuality on its own terms, instead of as reality-negative, by showcasing four perspectives of social interaction in virtual space. Panelists ...

Abstract. We give a goal-oriented a posteriori error estimator for the atomistic-continuum modeling error in the quasicontinuum method, and we use this estimator to design an adaptive algorithm to compute a quantity of interest to a given tolerance by using a nearly minimal number of atomistic degrees of freedom. We present computational results that demonstrate the effectiveness of our algorit...

Learning is an active, constructive and collaborative process, where people construct know ledge from their experiences in the world. Especially children need to learn through their senses and through physical activity. However, there are few experiental learning environments for school children available, which involve the senses and physical activity. Reasons put forward for this situation ar...

Excellent expository articles regarding the cardinal charactersitcs of the continuum are A. Blass, Combinatorial Cardinal Characteristics of the Continuum (see [2]) and T. Bartoszynski, Invariants of measure and category (see [1]). Both of those articles should be available on-line, but if you cannot access them, please contact me to get a copy. In addition, for those students in the class, who...

Continuum percolation for Markov (or Gibbs) germ-grain models in dimension 2 is investigated. The grains are assumed circular with random radii on a compact support. The morphological interaction is the so-called Quermass interaction defined by a linear combination of the classical Minkowski functionals (area, perimeter and Euler-Poincaré characteristic). We show that percolation occurs for any...

A model for total cross sections with virtual photons is presented. In particular γp and γγ cross sections are considered. Our approach extends on a model for photoproduction, where the total cross section is subdivided into three distinct event classes: direct, VMD and anomalous. With increasing photon virtuality, the latter two decrease in importance. Instead Deep Inelastic Scattering dominat...

2014 The form of the failure probability distribution for discrete and continuum percolation in the critical region is obtained. The existence of bond-strength fluctuations in continuum percolation changes the distribution from a very steep form (at least an exponential of an exponential) to a Weibull-like form (exponential of a powerlaw). Futhermore, a size effect of the typical failure streng...