Bulk, surface and corner free energy series for the chromatic polynomial on the square and triangular lattices

We present an efficient algorithm for computing the partition function of the q-colouring problem (chromatic polynomial) on regular two-dimensional lattice strips. Our construction involves writing the transfer matrix as a product of sparse matrices, each of dimension ~ 3^m, where m is the number of lattice spacings across the strip. As a specific application, we obtain the large-q series of the bulk, surface and corner free energies of the chromatic polynomial. This extends the existing series for the square lattice by 32 terms, to order q^{-79}. On the triangular lattice, we verify Baxter's analytical expression for the bulk free energy (to order q^{-40}), and we are able to conjecture exact product formulae for the surface and corner free energies.Comment: 17 pages. Version 2: added 4 further term to the serie

Transient polarization dynamics in a CO2_2 laser

We study experimentally and theoretically the polarization alternation during the switch-on transient of a quasi-isotropic CO$_2$ laser emitting on the fundamental mode. The observed transient dynamics is well reproduced by means of a model which provides a quantitative discrimination between the intrinsic asymmetry due to the kinetic coupling of molecules with different angular momenta, and the extrinsic anisotropies, due to a tilted intracavity window. Furthermore, the experiment provides a numerical assignment for the decay rate of the coherence term for a CO$_2$ laser.Comment: 14 pages, 6 figures, submitted to Opt. Com

The level of compliance of Russian and European rails standards on groups of indicators: the design and dimensions of rails

It is proved that the level of compliance of national and international standards determines the competitiveness of products. GOST R 51685–2013 «Railway rails. General technical conditions» is a new stage in the struggle for the competitiveness of domestic rails. The level of compliance of requirements imposed on the rails in the national standard GOST R 51685–2013 and the European Standard EN 13674–1–2011on the group of indicators: design and dimensions of the rails on the four-point of scale comparison is comparedДоказывется, что уровень соответствия требований национальных и международных стандартов определяет конкурентоспособность продукции. Утверждается, что ГОСТ Р 51685–2013 «Рельсы железнодорожные. Общие технические условия» – новая ступень в борьбе за конкурентоспособность отечественных рельсов. Сравнивается уровень соответствия требований, предъявляемых к рельсам, в национальном стандарте ГОСТ Р 51685–2013 и европейском стандарте EN 13674–1–2011, по группе показателей: конструкция и размеры рельсов по четырехбалльной шкале сравнени

Transfer Matrices and Partition-Function Zeros for Antiferromagnetic Potts Models. V. Further Results for the Square-Lattice Chromatic Polynomial

We derive some new structural results for the transfer matrix of square-lattice Potts models with free and cylindrical boundary conditions. In particular, we obtain explicit closed-form expressions for the dominant (at large |q|) diagonal entry in the transfer matrix, for arbitrary widths m, as the solution of a special one-dimensional polymer model. We also obtain the large-q expansion of the bulk and surface (resp. corner) free energies for the zero-temperature antiferromagnet (= chromatic polynomial) through order q^{-47} (resp. q^{-46}). Finally, we compute chromatic roots for strips of widths 9 <= m <= 12 with free boundary conditions and locate roughly the limiting curves.Comment: 111 pages (LaTeX2e). Includes tex file, three sty files, and 19 Postscript figures. Also included are Mathematica files data_CYL.m and data_FREE.m. Many changes from version 1: new material on series expansions and their analysis, and several proofs of previously conjectured results. Final version to be published in J. Stat. Phy

Antidepressants of the Serotonin-Antagonist Type Increase Body Fat and Decrease Lifespan of Adult Caenorhabditis elegans

It was recently suggested that specific antidepressants of the serotonin-antagonist type, namely mianserin and methiothepin, may exert anti-aging properties and specifically extend lifespan of the nematode C.elegans by causing a state of perceived calorie restriction (Petrascheck M, Ye X, Buck LB: An antidepressant that extends lifespan in adult Caenorhabditis elegans; Nature, Nov 22, 2007;450(7169):553–6, PMID 18033297). Using the same model organism, we instead observe a reduction of life expectancy when employing the commonly used, standardized agar-based solid-phase assay while applying the same or lower concentrations of the same antidepressants. Consistent with a well-known side-effect of these compounds in humans, antidepressants not only reduced lifespan but also increased body fat accumulation in C. elegans reflecting the mammalian phenotype. Taken together and in conflict with previously published findings, we find that antidepressants of the serotonin-antagonist type not only promote obesity, but also decrease nematode lifespan

Wettability Modification of Nanomaterials by Low-Energy Electron Flux

Controllable modification of surface free energy and related properties (wettability, hygroscopicity, agglomeration, etc.) of powders allows both understanding of fine physical mechanism acting on nanoparticle surfaces and improvement of their key characteristics in a number of nanotechnology applications. In this work, we report on the method we developed for electron-induced surface energy and modification of basic, related properties of powders of quite different physical origins such as diamond and ZnO. The applied technique has afforded gradual tuning of the surface free energy, resulting in a wide range of wettability modulation. In ZnO nanomaterial, the wettability has been strongly modified, while for the diamond particles identical electron treatment leads to a weak variation of the same property. Detailed investigation into electron-modified wettability properties has been performed by the use of capillary rise method using a few probing liquids. Basic thermodynamic approaches have been applied to calculations of components of solid–liquid interaction energy. We show that defect-free, low-energy electron treatment technique strongly varies elementary interface interactions and may be used for the development of new technology in the field of nanomaterials

Multiscale modelling for fusion and fission materials: the M4F project

The M4F project brings together the fusion and fission materials communities working on the prediction of radiation damage production and evolution and its effects on the mechanical behaviour of irradiated ferritic/martensitic (F/M) steels. It is a multidisciplinary project in which several different experimental and computational materials science tools are integrated to understand and model the complex phenomena associated with the formation and evolution of irradiation induced defects and their effects on the macroscopic behaviour of the target materials. In particular the project focuses on two specific aspects: (1) To develop physical understanding and predictive models of the origin and consequences of localised deformation under irradiation in F/M steels; (2) To develop good practices and possibly advance towards the definition of protocols for the use of ion irradiation as a tool to evaluate radiation effects on materials. Nineteen modelling codes across different scales are being used and developed and an experimental validation programme based on the examination of materials irradiated with neutrons and ions is being carried out. The project enters now its 4th year and is close to delivering high-quality results. This paper overviews the work performed so far within the project, highlighting its impact for fission and fusion materials science.This work has received funding from the Euratom research and training programme 2014-2018 under grant agreement No. 755039 (M4F project)

A new species of Burguklia (Pisces, Actinopterygii) from the Middle Permian of the Volga Region (European Russia)

© 2019, Paläontologische Gesellschaft. A new species of early actinopterygians, Burguklia minichorum sp. nov., is described based on the occurrence of numerous isolated scales from freshwater deposits of the Urzhumian and Severodvinian regional stages (Wordian–Capitanian) of the East European Platform. The type and only hitherto known species of the genus, Burguklia gdali Kazantseva-Selezneva, 1980, comes from the Early Permian of Siberia. The new discovery indicates the existence of non-marine palaeogeographic pathways between Siberia and European Russia during the Permian

A new species of Burguklia (Pisces, Actinopterygii) from the Middle Permian of the Volga Region (European Russia)

© 2019, Paläontologische Gesellschaft. A new species of early actinopterygians, Burguklia minichorum sp. nov., is described based on the occurrence of numerous isolated scales from freshwater deposits of the Urzhumian and Severodvinian regional stages (Wordian–Capitanian) of the East European Platform. The type and only hitherto known species of the genus, Burguklia gdali Kazantseva-Selezneva, 1980, comes from the Early Permian of Siberia. The new discovery indicates the existence of non-marine palaeogeographic pathways between Siberia and European Russia during the Permian