The Kinetic Interpretation of the DGLAP Equation, its Kramers-Moyal Expansion and Positivity of Helicity Distributions

According to a rederivation - due to Collins and Qiu - the DGLAP equation can be reinterpreted (in leading order) in a probabilistic way. This form of the equation has been used indirectly to prove the bound $|\Delta f(x,Q)| < f(x,Q)$ between polarized and unpolarized distributions, or positivity of the helicity distributions, for any $Q$. We reanalize this issue by performing a detailed numerical study of the positivity bounds of the helicity distributions. To obtain the numerical solution we implement an x-space based algorithm for polarized and unpolarized distributions to next-to-leading order in $\alpha_s$, which we illustrate. We also elaborate on some of the formal properties of the Collins-Qiu form and comment on the underlying regularization, introduce a Kramers-Moyal expansion of the equation and briefly analize its Fokker-Planck approximation. These follow quite naturally once the master version is given. We illustrate this expansion both for the valence quark distribution $q_V$ and for the transverse spin distribution $h_1$.Comment: 38 pages, 27 figures, Dedicated to Prof. Pierre Ramond for his 60th birthda

The Status and Job Satisfaction of Computer Operators

Le but de la présente recherche visait à vérifier, parmi un groupe d'opérateurs d'ordinateurs, comment l'image qu'ils se faisaient de leur propre statut professionnel réagissait sur le degré de leur propre satisfaction au travail. On a choisi cette entité professionnelle spécifique à cause du prestige dont est entourée l'utilisation de machines à calculer électroniques et de l'échelon relativement bas où se trouvent placés les préposés aux ordinateurs dans la hiérarchie des fonctions à l'intérieur d'un service d'ordinateurs.Il devenait, en conséquence, possible d'analyser les contradictions attachées à ce statut précis, ce qui a permis la vérification des hypothèses suivantes :1. Les personnes étrangères au service des ordinateurs se font de l'opérateur une image plus reluisante que ceux qui travaillent dans ce domaine.2. L'interaction entre ces deux groupes porte celui-ci à situer son propre statut professionnel à un niveau plus élevé que celui que lui accorde le personnel du service, mais sous le niveau qui lui est donné par les gens de l'extérieur.3. La contradiction créée par les opinions divergentes des deux groupes (les gens de l'intérieur et les étrangers) a pour conséquence que les opérateurs ne se font pas tous la même idée de la valeur de leur statut professionnel. En conséquence, on peut s'attendre à une corrélation affirmative (fonction de cette contradiction) entre la façon dont l'opérateur perçoit son statut professionnel et son degré de satisfaction au travail.Les constatations de cette enquête permettent de conclure que le préposé aux ordinateurs occupe une position ambiguë dans la hiérarchie des fonctions en tant que son statut professionnel est concerné. Les gens de l'intérieur considèrent que cette fonction occupe un rang plutôt inférieur dans la hiérarchie des emplois, tandis que, pour les étrangers, la fascination d'avoir à travailler avec ces machines à calculer place un halo autour du statut professionnel de l'opérateur.Il semble qu'il y ait un certain rapport, du moins lorsque le statut professionnel est bas, entre ce statut et la satisfaction au travail. Il faut cependant en interpréter le résultat avec circonspection, étant donné qu'aucune tentative n'a été faite pour contrôler l'un quelconque des antécédents se rapportant au statut professionnel, à l'exception du niveau de l'emploi dans la hiérarchie des fonctions. Aussi, la corrélation que l'on a trouvée dans l'une des deux entreprises où les recherches se sont faites peut bien n'être que l'influence d'autres facteurs comme le salaire, les conditions de travail ou l'ancienneté qui peuvent influer tant sur le statut professionnel que la satisfaction au travail.The results of this exploratory study suggest that computer operators experience a high level of inconsistency in their occupational status. Such inconsistency produces a differential impact upon the satisfaction of computer operators. When operators resolve the inconsistency by seeing their own status as low, they tend to be dissatisfied ; when they see their own status as high, they tend to be satisfied

Transverse preputial island flap technique for hypospadias

Introduction: The preputial island flap can be used for urethral reconstruction in congenital or aquired defects. Method: We describe the technique with transverse preputial island flap utilised as reconstructive procedure at a 9 years old male patient with medium penile hypospadias. He has had in the past 2 failures of surgical treatment. We try to point out the contribution of the artificial erection and release of the fibrous chordee for orthoplasty. The orthotopic position of the meatus is important for micturition and fecundation. Conclusions: DUCKETT PROCEDURE is a surgical technique for hypospadias with good cosmetique, functional and emotional results

Harnessing Remote Sensing to Accomplish Full Carbon Accounting: Workshop Report

The workshop "Harnessing Remote Sensing to Accomplish Full Carbon Accounting" was held on December 9-11th, 1999 at IIASA with the intention of meeting the following objectives: (1) To Promote the mutual interests of remote sensing and carbon science communities by exchanging the ideas regarding the requirements for carbon accounting and the current available products derived from remote sensing land information systems; (2) To produce strategic recommendations on how to improve FCA at different scales with the use of remote sensing tools; and, (3) To develop a Framework to Apply Recommendations for Sub-global and National-Level Case Studies. Although these ambitious targets were only part met, three discussion group sessions resulted in describing: What is required to implement full carbon accounting; How remote sensing can be used to assist this implementation; and, How remote sensing can be used to reduce the uncertainties related to FCA. This report summarizes the presentations, discussions and results of this workshop and outlines the next steps to be taken by IIASA

Polarized Photoproduction of Heavy Quarks in Next-to-Leading Order

The results of a next-to-leading order calculation of heavy quark production in longitudinally polarized photon-nucleon collisions are presented. At c.m. energy $\sqrt{S}=10$ GeV, for $\vec \gamma +\vec p \to c+X$, cross sections differential in the transverse momentum and rapidity of the charmed quark $c$ and the corresponding asymmetries are presented; also, as functions of $\sqrt{S}$, integrated cross sections, $K$-factors and the corresponding asymmetries are given. Errors in the asymmetries are estimated and the possibility to distinguish between three scerarios differing essentially in the polarized gluon distribution is discussed.Comment: 8 pages, 3 figure

Uncertainties of the CJK 5 Flavour LO Parton Distributions in the Real Photon

Radiatively generated, LO quark (u,d,s,c,b) and gluon densities in the real, unpolarized photon, calculated in the CJK model being an improved realization of the CJKL approach, have been recently presented. The results were obtained through a global fit to the experimental F2^gamma data. In this paper we present, obtained for the very first time in the photon case, an estimate of the uncertainties of the CJK parton distributions due to the experimental errors. The analysis is based on the Hessian method which was recently applied in the proton parton structure analysis. Sets of test parametrizations are given for the CJK model. They allow for calculation of its best fit parton distributions along with F2^gamma and for computation of uncertainties of any physical value depending on the real photon parton densities. We test the applicability of the approach by comparing uncertainties of example cross-sections calculated in the Hessian and Lagrange methods. Moreover, we present a detailed analysis of the chi^2 of the CJK fit and its relation to the data. We show that large chi^2/DOF of the fit is due to only a few of the experimental measurements. By excluding them chi^2/DOF approx 1 can be obtained.Comment: 28 pages, 8 eps figures, 2 Latex figures; FORTRAN programs available at http://www.fuw.edu.pl/~pjank/param.html; table 10, figure 10 and section 6 correcte

Bloom-Gilman duality of the nucleon structure function and the elastic peak contribution

The occurrence of the Bloom-Gilman duality in the nucleon structure function is investigated by analyzing the Q**2-behavior of low-order moments, both including and excluding the contribution arising from the nucleon elastic peak. The Natchmann definition of the moments has been adopted in order to cancel out target-mass effects. It is shown that the onset of the Bloom-Gilman duality occurs around Q**2 ~ 2 (GeV/c)**2 if only the inelastic part of the nucleon structure function is considered, whereas the inclusion of the nucleon elastic peak contribution leads to remarkable violations of the Bloom-Gilman duality.Comment: in Proc. of the XVI European Conference on Few-body Problems in Physics, Autrans (France), July 199

Small x behaviour of parton distributions with soft initial conditions

We present an analytical parametrization of the QCD description of the small x behaviour of parton distribution functions in the leading twist approximation of the Wilson operator product expansion, in the case of soft initial conditions. The results are in very good agreement with deep inelastic scattering experimental data from HERA.Comment: 21 pages, latex + 3 ps figure

A QCD analysis of diffractive deep-inelastic scattering data

We perform a novel type of analysis of diffractive deep-inelastic scattering data, in which the input parton distributions of the Pomeron are parameterised using the perturbative QCD expressions. In particular, we treat individually the components of the Pomeron of different size. We are able to describe simultaneously both the recent ZEUS and H1 diffractive data. In addition to the usual two-gluon model for the perturbative Pomeron, we allow for the possibility that it may be made from two sea quarks.Comment: 13 pages, 5 figures. Version published in Eur. Phys. J.

Diffractive parton distributions from H1 data

We analyse the latest H1 large rapidity gap data to obtain diffractive parton distributions, using a procedure based on perturbative QCD, and compare them with distributions obtained from the simplified Regge factorisation type of analysis. The diffractive parton densities and structure functions are made publically available.Comment: 9 pages, 2 figures. Fortran code for diffractive parton densities and structure functions can be found at http://durpdg.dur.ac.uk/hepdata/mrw.html . Version to appear in Phys. Lett. B; final paragraph added, with curves from H1 incl.+dijet fit added to Fig.