Comment on “Experimental and theoretical study of the triple-differential cross section for electron-impact ionization of thymine molecules”

In their recent paper, Bellm et al. [Phys. Rev. A 85, 022710 (2012)] performed (e,2e) experiments on thymine at an incident energy of 250 eV. They wrote in the conclusion that a model based on the first Born approximation using the completely neglected differential overlap description is in very good agreement with the experimental data. On the contrary, we argue that this model fails to describe experiments on water performed at the same incident energy and is unable to explain any shift of the binary or recoil peaks

A quasi classical approach to electron impact ionization

A quasi classical approximation to quantum mechanical scattering in the Moeller formalism is developed. While keeping the numerical advantage of a standard Classical--Trajectory--Monte--Carlo calculation, our approach is no longer restricted to use stationary initial distributions. This allows one to improve the results by using better suited initial phase space distributions than the microcanonical one and to gain insight into the collision mechanism by studying the influence of different initial distributions on the cross section. A comprehensive account of results for single, double and triple differential cross sections for atomic hydrogen will be given, in comparison with experiment and other theories.Comment: 21 pages, 10 figures, submitted to J Phys

Global surveillance of cancer survival 1995-2009: analysis of individual data for 25,676,887 patients from 279 population-based registries in 67 countries (CONCORD-2)

BACKGROUND: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control. METHODS: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease. INTERPRETATION: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems

Description des collisions électroniques (e, 2 e) triplement différentielles : cas des cibles moléculaires

A specific perturbation treatment, presented in a previous article, was shown to reproduce the triply-differential (e, 2e) cross sections measured with high energy incident electron impinging on atomic targets, under asymmetric conditions of ejection. A first application to (e, 2 e ) studies of molecular targets is shown to explain the recent measurements on molecular hydrogen practized under those kinematical conditions.Un traitement particulier de perturbation, présenté dans un précédent article, permet de décrire correctement dans des cibles atomiques les mesures de sections efficaces (e, 2 e ) triplement différentielles à haute énergie incidente en situation asymétrique d'émergence. Une première tentative d'application à des cibles moléculaires est présentée ici pour la molécule d'hydrogène

Description des collisions électroniques triplement différentielles à faible transfert d'impulsion

Simple quantum-mechanical models are found to be in strong disagreement with all (e, 2e) triplydifferential cross sections measurements out of the strict impulse collisional conditions. The second order perturbation method proposed in this article is found to reproduce the Coulomb-wave behaviour of the electron ejected from a hydrogen target under (e, 2 e) asymmetric conditions. As illustrated by the discussion of the helium atom results, this method provides the unique ab initio treatment presently known to describe (e, 2 e) measurements performed upon non-hydrogenic targets and at small momentum transfers.Les modèles quantiques simples décrivant les sections efficaces triplement différentielles de collisions (e, 2e) apparaissent grossièrement faux lorsqu'on s'écarte des conditions impulsionnelles de choc. Le traitement particulier de perturbation proposé dans cet article reproduit au second ordre la trajectoire coulombienne d'éjection d'un électron atomique, comme le montre une étude détaillée du cas de l'atome d'hydrogène. Ce traitement fournit actuellement la seule interprétation simple, en régime asymétrique de collision, des résultats expérimentaux récents dont ceux relatifs à l'atome d'hélium qui serviront également de support à la discussion