Homotopical algebra in homotopical categories

We develop here a version of abstract homotopical algebra based onhomotopy kernels andcokernels, which are particular homotopy limits and colimits. These notions are introduced in anh-category, a sort of two-dimensional context more general than a 2-category, abstracting thenearly 2-categorical properties of topological spaces, continuous maps and homotopies. A setting which applies also, at different extents, to cubical or simplicial sets, chain complexes, chain algebras, ... and in which homotopical algebra can be established as a two-dimensional enrichment of homological algebra.Actually, a hierarchy of notions ofh-,h1-, ...h4-categories is introduced, through progressive enrichment of thevertical structure of homotopies, so that the strongest notion,h4-category, is a sort of relaxed 2-category. After investigating homotopy pullbacks and homotopical diagrammatical lemmas in these settings, we introduceright semihomotopical categories, ash-categories provided with terminal object and homotopy cokernels (mapping cones), andright homotopical categories, provided also with anh4-structure and verifying second-order regularity properties forh-cokernels.In these frames we study the Puppe sequence of a map, its comparison with the sequence of iterated homotopy cokernels and theh-cogroup structure of the suspension endofunctor. Left (semi-) homotopical categories, based on homotopy kernels, give the fibration sequence of a map and theh-group of loops. Finally, the self-dual notion of homotopical categories is considered, together with their stability properties.Lavoro esequito nell'ambito dei progetti di ricerca del MURST.     

Characterization of a Marshall-Olkin type class of distributions

Summary A class of bivariate distributions that generalize Marshall-Olkin's one is characterized through a functional equation which involves two associative operations. The obtained distributions concentrate positive mass on the linex=y when the two associative operations coincide; otherwise a positive mass is concentrated on a continuous monotone function. Work performed while the authors were members of CNR-GNAFA.     

The conformal Gauss map of submanifolds of the Möbius space

In this paper we study the conformal geometry of immersed submanifolds of the Möbius spaceS ⁿ introducing the conformal Gauss map. In particular we relate its harmonicity to an extended notion of Willmore surface which originated from the work of Bryant. For a more detailed account the reader is referred to the Introduction.(on leave)     

Mössbauer spectroscopic and SEM study of Campanian and Terra sigillata pottery from Spain

A combination of Mössbauer spectroscopy (CEMS and transmission) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX) was employed to study the differences between coat and body in Campanian and Terra Sigillata wares. Conclusions about type of clay, origin of colour, and fabric and firing technology are established.     

Proton-proton correlations at small relative momentum in neon-nucleus collisions at E/A=400 and 800 MeV

Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.     

Manganese precipitation in NaCl induced by room temperature X-irradiation

In the present paper, Electron Paramagnetic Resonance, Ionic Thermocurrents and photoluminescence (emission and excitation) measurements have been performed in crystals of manganese- doped NaCl which were exposured to room temperature X-irradiation. The results obtained indicate that the diffusion of the Mn²⁺ - cation vacancy dipoles, originally present in the quenched samples, is considerably enhanced by ionizing radiation leading to the formation of a second phase precipitate which appears to be related with the Suzuki phase of the manganese ions in the host NaCl, as revealed from the EPR and optical data.     

A Three-component Extension of the Camassa–Holm Hierarchy

We introduce a bi-Hamiltonian hierarchy on the loop-algebra of endowed with a suitable Poisson pair. It gives rise to the usual Camassa–Holm (CH) hierarchy by means of a bi-Hamiltonian reduction, and its first nontrivial flow provides a three-component extension of the CH equation.     

Ambient-Pressure X-ray Photoelectron Spectroscopy to Characterize the Solid/Liquid Interface: Probing the Electrochemical Double Layer

Ambient-pressure X-ray photoelectron spectroscopy (APXPS) has contributed greatly to a wide range of research fields, including environmental science [1 H. Bluhm, Journal of Electron Spectroscopy and Related Phenomena 177, 71–84 (2010).[Crossref], [Web of Science ®] , [Google Scholar]], catalysis [2 D.E. Starr et al., Chemical Society Reviews 42, 5833–5857 (2013).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], and electrochemistry [3 E.J. Crumlin, H. Bluhm, and Z. Liu, Journal of Electron Spectroscopy and Related Phenomena 190, 84–92 (2013).[Crossref], [Web of Science ®] , [Google Scholar]], to name a few. The use of this technique at synchrotron facilities primarily focused on probing the solid/gas interface; however, it quickly advanced to the probing of liquid/vapor interfaces [4 D.E. Starr et al., Physical Chemistry Chemical Physics 10, 3093–3098 (2008).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar], 5 M.A. Brown et al., Physical Chemistry Chemical Physics 10, 4778–4784 (2008).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] and solid/liquid interfaces through an X-ray-transparent window [6 J. Kraus et al., Nanoscale 6, 14394–14403 (2014).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]–8 T. Masuda et al., Appl Phys Lett 103 (2013).[Crossref], [Web of Science ®] , [Google Scholar]]. Most recently, combining APXPS with “Tender” X-rays (~2.5 keV to 8 keV) on beamline 9.3.1 at the Advanced Light Source in Lawrence Berkeley National Laboratory (which can generate photoelectrons with much longer inelastic mean free paths) has enabled us to probe the solid/liquid interface without needing a window [9 S. Axnanda et al., Scientific Reports 5 (2015).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. This innovation allows us to probe interfacial chemistries of electrochemically controlled solid/liquid interfaces undergoing charge transfer reactions [9 S. Axnanda et al., Scientific Reports 5 (2015).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. These advancements have transitioned APXPS from a traditional surface science tool to an essential interface science technique.     

Emergent <Emphasis Type=Italic>SO</Emphasis>(3) Symmetry of the Frictionless Shear Jamming Transition

We study the shear jamming of athermal frictionless soft spheres, and find that in the thermodynamic limit, a shear-jammed state exists with different elastic properties from the isotropically-jammed state. For example, shear-jammed states can have a non-zero residual shear stress in the thermodynamic limit that arises from long-range stress-stress correlations. As a result, the ratio of the shear and bulk moduli, which in isotropically-jammed systems vanishes as the jamming transition is approached from above, instead approaches a constant. Despite these striking differences, we argue that in a deeper sense, the shear jamming and isotropic jamming transitions actually have the same symmetry, and that the differences can be fully understood by rotating the six-dimensional basis of the elastic modulus tensor.