Leptons, Quarks, and Their Antiparticles: A?Phase-Space View

Recently, a correspondence has been shown to exist between the structure of a single Standard Model generation of elementary particles and the properties of the Clifford algebra of nonrelativistic phase space. Here, this correspondence is spelled out in terms of phase-space variables. Thus, a phase-space interpretation of the connections between leptons, quarks and their antiparticles is proposed, in particular providing a timeless alternative to the standard Stückelberg-Feynman interpretation. The issue of the additivity of canonical momenta is raised and argued to be intimately related to the unobservability of free quarks and the emergence of mesons and baryons.     

Unbound exciton–phonon states in oligothiophene crystals – A model approach for spectroscopic purposes

A simple model of exciton–phonon interaction in a crystal with one molecule in the unit cell is used to simulate some peculiar features of the oligothiophene absorption spectra. The model is treated in the limit of weak vibronic coupling, and the configuration interaction between the intense zero-phonon Frenkel state and the one-phonon continuum is described in terms of the Fano formalism. The good agreement between the calculated curve and a part of the experimental absorption profile allows one to discriminate some features that are physically relevant but are not accounted for in the model.     

KIDs are Non-Generic

We prove that the space-time developments of generic solutions of the vacuum constraint Einstein equations do not possess any global or local Killing vectors, when Cauchy data are prescribed on an asymptotically flat Cauchy surface, or on a compact Cauchy surface with mean curvature close to a constant, or for CMC asymptotically hyperbolic initial data sets. More generally, we show that nonexistence of global symmetries implies, generically, non-existence of local ones. As part of the argument, we prove that generic metrics do not possess any local or global conformal Killing vectors.submitted 22/02/04, accepted 28/07/04     

A novel hydroxy functionalized polyester obtained by ring opening copolymerization of L‐lactide with a pyrolysis product of cellulose

A hydroxylactone ((1R,5S)‐1‐hydroxy‐3,6‐dioxabicyclo [3.2.1] octan‐2‐one, abbreviated as LAC) obtained from catalytic pyrolysis of cellulose was investigated as a monomer in the synthesis of polyesters by ring‐opening polymerization (ROP) with L ‐lactide. Although stannous octoate resulted inactive, ROP initiated by zirconium (IV) acetylacetonate afforded novel copolyesters from LAC and lactide mixtures in the bulk at 110 °C. Copolymers were obtained with different LAC content (from 19 to 45%) with a random microstructure as established by detailed NMR analysis. FTIR spectrometry confirmed the presence in the polymer chain of the OH groups originally present in LAC, which do not react during polymerization due to steric hindrance and inter/intramolecular hydrogen bonding. Reaction with trichloroacetylisocyanide proved that OH groups of the polyesters can be readily derivatized. The application of LAC as a comonomer enables the insertion of the alcohol functionality in polylactide avoiding protection/deprotection steps and potentially expanding the realm of biomaterials affordable from carbohydrate feedstock. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 247–257, 2009     

Macromolecular nature of nanosheets of quasi‐TiO2 from (tetra‐isopropyl)orthotitanate modified by methacrylic acid

In this paper we concentrate on the general behavior of oxotitanium hydrosol, which was earlier developed by us as a precursor of the TiO₂ nanoparticles and nanocomposite. The oxotitanium hydrosol was synthesized by the chemical decomposition of a molecular complex of the methacrylic acid/(tetra‐isopropyl)orthotitanate (MAA/TIPT) by means of the hydrogen peroxide. The raw product chemical decomposition of MAA/TIPT is the colloidal suspension of the oxotitanium compound in the water. The oxotitanium compound was separated from hydrosol and identified on the basis of X‐ray and Raman spectroscopy investigations. The status of water in the hydrosol was also investigated by the Raman spectroscopy. The photophysical behaviors of the oxotitanium hydrosol on the basis of the light absorption and photoluminescence (PL) investigations are presented. The light absorption (260 nm) and PL emission (313 nm) allow us to identify the inorganic phase of hydrosol as nanosheets' crystallites of quasi‐TiO₂. Macromolecular nature of nanosheets of quasi‐TiO₂ was revealed only for a higher concentration solution of nanosheets' crystallites of quasi‐TiO₂ at the hydrosol. A macromolecular nature of nanosheets of quasi‐TiO₂ by the red shift of absorption edge and PL wavelength with increase in the concentration of the oxotitanium hydrosol as well as the formation of hydrogels and birefringence developed under an influence of mechanical shearing is evidenced. Copyright © 2009 John Wiley & Sons, Ltd.     

Strain coupling and scaling invariants in search for effective critical parameters of uniaxial ferroelectrics

A scaling equation of state giving a realistic ratio of Curie–Weiss constants and accounting for coupling of the order parameter with a strain (secondary order parameter) is used to describe the temperature dependence of the electric susceptibility in an external biasing field applied in case of uniaxial ferroelectrics. Explicit expressions for the resulting scaling invariants are given. The power laws for the temperature and field dependence of the maxima and of the inflection points of the susceptibility curves are found. The theory is exemplified by the effective critical behaviour of iono-molecular crystals (CH₃NH₃)₅Bi₂Cl₁₁ (MAPCB) and (CH₃NH₃)₅Bi₂Br₁₁ (MAPBB).     

On measurable multifunctions in countably separated spaces

We use an idea of countable separability of points and sets in topological spaces to prove results on intersection of measurable multifunctions and an implicit function theorem. We generalize or extend in part some well known Himmelberg's theorems.     

Isoperimetry of group actions

The isoperimetric profile of a discrete group was introduced by Vershik, however it is well defined only for a restrictive class amenable groups. We generalize the notion of isoperimetric profile beyond the world of amenable groups by defining isoperimetric profiles of amenable actions of finitely generated groups on compact topological spaces. This allows to extend the definition of the isoperimetric profile to all groups which are exact in such a way that for amenable groups it is equal to Vershik's isoperimetric profile. The main feature of our construction is that it preserves many of the properties known from the classical case. We use these results to compute exact asymptotics of the isoperimetric profiles for several classes of non-amenable groups.     

Machine Learning Algorithms for Prediction of the Quality of Transmission in Optical Networks

Increasing demand in the backbone Dense Wavelength Division (DWDM) Multiplexing network traffic prompts an introduction of new solutions that allow increasing the transmission speed without significant increase of the service cost. In order to achieve this objective simpler and faster, DWDM network reconfiguration procedures are needed. A key problem that is intrinsically related to network reconfiguration is that of the quality of transmission assessment. Thus, in this contribution a Machine Learning (ML) based method for an assessment of the quality of transmission is proposed. The proposed ML methods use a database, which was created only on the basis of information that is available to a DWDM network operator via the DWDM network control plane. Several types of ML classifiers are proposed and their performance is tested and compared for two real DWDM network topologies. The results obtained are promising and motivate further research.