Fine structure in the gamma-ray sky and the origin of UHECR

The EGRET results for gamma ray intensities in and near the Galactic Plane have been analysed in some detail. Attention has been concentrated on energies above 1 GeV and the individual intensities in a $4^{\circ}$ longitude bin have been determined and compared with the large scale mean found from a nine-degree polynomial fit. Comparison has been made of the observed standard deviation for the ratio of these intensities with that expected from variants of our model. The basic model adopts cosmic ray origin from supernova remnants, the particles then diffusing through the Galaxy with our usual `anomalous diffusion'. The variants involve the clustering of SN, a frequency distribution for supernova explosion energies, and 'normal', rather than 'anomalous' diffusion. It is found that for supernovae of unique energy, and our usual anomalous diffusion, clustering is necessary, particularly in the Inner Galaxy. An alternative, and preferred, situation is to adopt the model with a frequency distribution of supernova energies. The results for the Outer Galaxy are such that no clustering is required. If their explosion energies are distributed then supernovae can be the origin of UHECR.Comment: 8 pages, 5 figures and 1 table, to appear in the proceedings of the CRIS2006 symposium, Catania, Italy, May-June 200

Models for the Origin of the Knee in the Cosmic-Ray Spectrum

A sudden steepening of the cosmic-ray energy spectrum (the knee) is observed at an energy of about 3 PeV (1 PeV = $10^{15}$ eV). The experimental study of the PeV cosmic rays has intensified greatly during the last 3 years. The recent results on extensive air showers allow us to conclude that: a) the knee has an astrophysical origin; b) the `sharpness' and the fine structure of the knee rule out `Galactic Modulation' as the origin of the knee; c) most likely the knee is the result of the explosion of a single, recent, nearby supernova.Comment: 10 pages, 6 figures, submitted to Advances in Space Researc

Do pathologists agree with each other on the histological assessment of pT1b oesophageal adenocarcinoma?

Background: In early (T1) oesophageal adenocarcinoma (OAC), the histological profile of an endoscopic resection specimen plays a pivotal role in the prediction of lymph node metastasis and the potential need for oesophagectomy with lymphadenectomy. Objective: To evaluate the inter-observer agreement of the histological assessment of submucosal (pT1b) OAC. Methods: Surgical and endoscopic resection specimens with pT1b OAC were independently reviewed by three gastrointestinal pathologists. Agreement was determined by intraclass correlation coefficient for continuous variables, and Fleiss' kappa (κ) for categorical variables. Bland–Altman plots of the submucosal invasion depth were made. Results: Eighty-five resection specimens with pT1b OAC were evaluated. The agreement was good for differentiation grade (κ=0.77, 95% confidence interval (CI) 0.68–0.87), excellent for lymphovascular invasion (κ=0.88, 95% CI 0.76–1.00) and moderate for submucosal invasion depth using the Paris and Pragmatic classifications (κ=0.60, 95% CI 0.49–0.72 and κ=0.42, 95% CI 0.33–0.51, respectively). Systematic mean differences between pathologists were detected for the measurement of submucosa

Organic Superconductors: when correlations and magnetism walk in

This survey provides a brief account for the start of organic superconductivity motivated by the quest for high Tc superconductors and its development since the eighties'. Besides superconductivity found in 1D organics in 1980, progresses in this field of research have contributed to better understand the physics of low dimensional conductors highlighted by the wealth of new remarkable properties. Correlations conspire to govern the low temperature properties of the metallic phase. The contribution of antiferromagnetic fluctuations to the interchain Cooper pairing proposed by the theory is borne out by experimental investigations and supports supercondutivity emerging from a non Fermi liquid background. Quasi one dimensional organic superconductors can therefore be considered as simple prototype systems for the more complex high Tc materials.Comment: 41 pages, 21 figures to be published in Journal of Superconductivity and Novel Magnetis

Learning finite-state machines from inexperienced teachers

– Extended Abstract – The general goal of query-based learning algorithms for finite-state machines is to identify a machine, usually of minimum size, that agrees with an a priori fixed (class of) machines. For this, queries on how the underlying system behaves may be issued. A popular setup is that of Angluin’s L ∗ algorithm[Ang87], here adapted to the case of finite-state machines, in which a minimal deterministic finite-state machine for a regular language is learned based on so-called membership and equivalence queries. Using a pictorial language, we have a learner whose job is to come up with the automaton to learn, a teacher who may answer the output for a given input string as well an oracle answering whether the automaton H currently proposed by the learner is correct or not. This setting is depicted in Figure 1(a) (though assume that the don’t know is not there). In Angluin’s setting, a teacher will always answer with the correct output symbol. In many application scenarios, however, parts of the machine to learn are not completely specified or not observable. Then, queries may be answered inconclusively, by don’t know, also denoted by?. In the full version of this paper [GL06], we study a learning algorithm (and variants thereof), called ABSAT, ABSATI, and ABSATI2, that are designed to work with such an inexperienced teacher. The oracle, however, does not change its functionality in the setting discussed here (see Figure 1(a), the don’t know is new). What is output for input string u? Learner Is H equivalent to system to learn