Small Angle Polarization in High Energy P--P Scattering Through Nonperturbative Chiral Symmetry Breaking

We show that a large anomalous contribution due to nonperturbative instanton-like gluonic field configurations to the axial charge of the proton implies high-energy spin effects in $p-p$ elastic scattering. This is the same mechanism which is responsible for anomalous baryon number violation at high energy in the standard model. We compute the proton polarization due to these effects and we show that it is proportional to the center-of-mass scattering angle with a universal (energy-independent) slope of order unity.Comment: (13 pages, 2 figures

Criteria for Bayesian model choice with application to variable selection

In objective Bayesian model selection, no single criterion has emerged as dominant in defining objective prior distributions. Indeed, many criteria have been separately proposed and utilized to propose differing prior choices. We first formalize the most general and compelling of the various criteria that have been suggested, together with a new criterion. We then illustrate the potential of these criteria in determining objective model selection priors by considering their application to the problem of variable selection in normal linear models. This results in a new model selection objective prior with a number of compelling properties.Comment: Published in at http://dx.doi.org/10.1214/12-AOS1013 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

A reappraisal of postglacial decay times from Richmond Gulf and James Bay, Canada

Decay times inferred from relative sea-level (RSL) histories of previously glaciated regions provide a potentially important constraint on mantle rheology. We present a new compilation of RSL data from Richmond Gulf and James Bay, Canada. This recompilation reveals errors in previous compilations that led to inaccurate estimates for the Richmond Gulf decay time in a series of recently published articles. We derive updated estimates for the decay time at Richmond Gulf and James Bay using a methodology that incorporates errors in both the age and the height of the sea-level markers. This exercise is guided by a series of synthetic RSL calculations that show that decay time estimates in the region can be significantly biased if the RSL time-series are not corrected for global eustatic sea-level trends, or if the estimates are based on composite RSL histories derived by combining data from both the Richmond Gulf and the James Bay regions. Our decay time analysis for Richmond Gulf applies the pioneering approach of Walcott (1980) to a large database and we derive a value of 4.0-6.6 kyr, where the range is defined by a misfit tolerance 10 per cent higher than the minimum. Our analysis for James Bay is based on the uplift curve derived by Hardy (1976), and we estimate a decay time of about 2.0-2.8 kyr. The difference between our estimates for Richmond Gulf and James Bay may be due to errors in the observational record from these regions, but could also be influenced by lateral variations in lithospheric structure associated with the assembly of Laurentia

Funcionalização de substratos de carbono por electrografting com sais de diazónio

[Excerto] A funcionalização de superfícies com sais de diazónio tem sido apresentada como um método eficiente, versátil, aplicável e simples a diversos substratos possibilitando várias aplicações. O electrografting representa um mecanismo de ligação dos grupos arilo à superfície formando camadas finas. Estas camadas podem ser caracterizadas por diferentes métodos de análise, por exemplo, IR, XPS, AFM, STM e eletroquímica. [...

Equilibrium molecular energies used to obtain molecular dissociation energies and heats of formation within the bond-order correlation approach

Ab initio calculations including electron correlation are still extremely costly except for the smallest atoms and molecules. Therefore, our purpose in the present study is to employ a bond-order correlation approach to obtain, via equilibrium molecular energies, molecular dissociation energies and heats of formation for some 20 molecules containing C, H, and O atoms, with a maximum number of electrons around 40. Finally, basis set choice is shown to be important in the proposed procedure to include electron correlation effects in determining thermodynamic properties. With the optimum choice of basis set, the average percentage error for some 20 molecules is approximately 20% for heats of formation. For molecular dissociation energies the average error is much smaller: ~0.4.Comment: Mol. Phys., to be publishe

Progress on neural parton distributions

We give a status report on the determination of a set of parton distributions based on neural networks. In particular, we summarize the determination of the nonsinglet quark distribution up to NNLO, we compare it with results obtained using other approaches, and we discuss its use for a determination of $\alpha_s$.Comment: 4 pages, 2 figs, uses dis2007.cls, to appear in the DIS 2007 workshop proceeding

Recent progress on NNPDF for LHC

We present recent results of the NNPDF collaboration on a full DIS analysis of Parton Distribution Functions (PDFs). Our method is based on the idea of combining a Monte Carlo sampling of the probability measure in the space of PDFs with the use of neural networks as unbiased universal interpolating functions. The general structure of the project and the features of the fit are described and compared to those of the traditional approaches.Comment: 4 pages, 6 figures, contribution for the proceedings of the conference "Rencontres de Moriond, QCD and High Energy Interactions

Recent advances in the integrated geophysical exploration of buried archaeological targets

We propose the integration of magnetic, electromagnetic (groundpenetrating radar, GPR) and seismic methods to study the inner structure of prehistoric funerary mounds. The combination of techniques allows high-resolution imaging and detection of buried targets and characterization of subsurface materials based on magnetic susceptibility, dielectric permittivity, conductivity and seismic velocity/attenuation. The 2012 archaeo-geophysical expedition to Scythian necropoleis in Kazakhstan allowed advancement of the integrated procedure through optimization of the individual techniques. We improve the results of seismic tomography inversion through an ART algorithm with a relaxation parameter which is progressively reduced during the iterative reconstruction process. We use instantaneous attributes and spectral decomposition to improve the interpretation of GPR reflection data. The results obtained from the 2012 dataset allow detailed reconstruction of the inner structure of three kurgans (i.e. funerary mounds) with maximum 7m central elevation. In particular, localized anomalies related to metallic targets smaller than the GPR and seismic resolution limits are identified from magnetic data after high pass filtering; GPR data allow imaging of inner stratigraphy up to a maximum depth of about 250 cm; seismic tomography maps large traveltime anomalies probably related to funerary chambers at the base of the mound