The boundary of the first order chiral phase transition in the m_pi-m_K--plane with a linear sigma model

Tree-level and complete one-loop parametrisation of the linear sigma model (LSM) is performed and the phase boundary between first order and crossover transition regions of the m_pi-m_K-plane is determined using the optimised perturbation theory (OPT) as a resummation tool of perturbative series. Away from the physical point the parameters of the model were determined by making use of chiral perturbation theory (ChPT). The location of the phase boundary for m_pi=m_K and of the tricritical point (TCP) on the m_pi=0 were estimated.Comment: 4 pages, 1 figure, uses espcrc1.sty; to appear in the proceedings of Strong and Electroweak Matter 2006 (SEWM06), BNL, May 200

Are polymer melts "ideal"?

It is commonly accepted that in concentrated solutions or melts high-molecular weight polymers display random-walk conformational properties without long-range correlations between subsequent bonds. This absence of memory means, for instance, that the bond-bond correlation function, $P(s)$, of two bonds separated by $s$ monomers along the chain should exponentially decay with $s$. Presenting numerical results and theoretical arguments for both monodisperse chains and self-assembled (essentially Flory size-distributed) equilibrium polymers we demonstrate that some long-range correlations remain due to self-interactions of the chains caused by the chain connectivity and the incompressibility of the melt. Suggesting a profound analogy with the well-known long-range velocity correlations in liquids we find, for instance, $P(s)$ to decay algebraically as $s^{-3/2}$. Our study suggests a precise method for obtaining the statistical segment length \bstar in a computer experiment.Comment: 4 pages, 3 figure

Comment on: a two-stage fourth-order “almost” P-stable method for oscillatory problems

AbstractIn Chawla and Al-Zanaidi (J. Comput. Appl. Math. 89 (1997) 115–118) a fourth-order “almost” P-stable method for y″=f(x,y) is proposed. We claim that it is possible to retrieve this combination of multistep methods by means of the theory of parameterized Runge-Kutta-Nyström (RKN) methods and moreover to generalize the method discussed by Chawla and Al-Zanaidi (J. Comput. Appl. Math. 89 (1997) 115–118)

Information dynamics: patterns of expectation and surprise in the perception of music

This is a postprint of an article submitted for consideration in Connection Science © 2009 [copyright Taylor & Francis]; Connection Science is available online at:http://www.tandfonline.com/openurl?genre=article&issn=0954-0091&volume=21&issue=2-3&spage=8

Origin of strong scarring of wavefunctions in quantum wells in a tilted magnetic field

The anomalously strong scarring of wavefunctions found in numerical studies of quantum wells in a tilted magnetic field is shown to be due to special properties of the classical dynamics of this system. A certain subset of periodic orbits are identified which are nearly stable over a very large interval of variation of the classical dynamics; only this subset are found to exhibit strong scarring. Semiclassical arguments shed further light on why these orbits dominate the experimentally observed tunneling spectra.Comment: RevTeX, 5 page

Hydrodynamics of polar liquid crystals

Starting from a microscopic definition of an alignment vector proportional to the polarization, we discuss the hydrodynamics of polar liquid crystals with local $C_{\infty v}$-symmetry. The free energy for polar liquid crystals differs from that of nematic liquid crystals ($D_{\infty h}$) in that it contains terms violating the ${\bf{n}}\to -{\bf{n}}$ symmetry. First we show that these $\mathcal{Z}_2$-odd terms induce a general splay instability of a uniform polarized state in a range of parameters. Next we use the general Poisson-bracket formalism to derive the hydrodynamic equations of the system in the polarized state. The structure of the linear hydrodynamic modes confirms the existence of the splay instability.Comment: 9 pages, corrected typos, added references, revised content, to appear in PR

Energy efficiency (EE) and cost-effective means to increase EE and to mitigate the climate change of pork and broiler meat production in five European countries

Production of pork and broiler meat in the European Union (EU) has increased by 7.8 and 16.1%, respectively, in the period of 2001 – 2011. At that time pork and broiler meat produced, amounted together to over four times the cattle meat. Meat is an important protein source in human diet, but on the other hand, livestock uses globally 30% of ice-free terrestrial land and produces 18% of global greenhouse gas (GHG) emissions. This exceeds the global emissions of the transport sector. Furthermore, energy ratio (output/input) for meat production is less than 1.0 in general and it is much lower than that of plant production. This paper presents cost-effectiveness of EE measures in pork and broiler meat production and it is based on the results of the Agriculture and Energy Efficiency Project (www.AGREE.aua.gr). The structure of the energy input appeared to be very similar in pork and broiler meat production. Feed was found to be the major indirect energy input. Its contribution to the total energy demand varied from 51% to 82% in pork production and from 55% to 94% in broiler meat production. The percentage of feed was the lowest in the Northern European countries and the highest in the south. This difference was mainly attributable to the demand for heating of animal houses during the winter period. Differences could also be found in the absolute energy input of feed. It indicated that there may be possibilities to improve feeding strategies or feed conversation rate of animals. In pork production, the energy input of feed was 12.5 GJ t-1 (live weight) in average and 8.6 GJ t-1 (live weight) in broiler production. The difference between pork and broiler meat is a consequence of the higher feed conversation rate of broilers in contrast to pigs. The category “Other energy use” was the second highest energy input and it consisted of energy input for ventilation, illumination, feeding, and heating of animal houses. In pork production, the input of this category was 4.7 GJ t-1 (live weight) in average (25% from the total energy input) and 2.4 GJ t-1 (live weight) in broiler meat production (22% from the total energy input). The specific energy input in pork production was the lowest in The Netherlands ( 14.5 GJ t-1) and that of broiler meat production in Germany (9.8 GJ t-1). Case studies analysed in five participating countries demonstrated EE measures capable to reduce costs, to increase EE, and to cut GHG emissions at the same time. Proposed EE measures were related to ventilation, heating, feeding, animal bedding, energy generation from manure, and feed production. As an example, an airtight grain storage met all three goals at the same time. Investment costs were lower than those for a grain dryer, no energy was needed for drying, and no GHG emissions were generated because no gas or oil was needed for drying. All suggested EE measures were not as successful. They might appear negative for costs but positive for EE and GHG reduction, resulting in a trade-off situation. An approach like this helps to rank potential EE measures in terms of their cost-effectiveness and capability to cut GHG emissions

A theorem on the absence of phase transitions in one-dimensional growth models with onsite periodic potentials

We rigorously prove that a wide class of one-dimensional growth models with onsite periodic potential, such as the discrete sine-Gordon model, have no phase transition at any temperature $T>0$. The proof relies on the spectral analysis of the transfer operator associated to the models. We show that this operator is Hilbert-Schmidt and that its maximum eigenvalue is an analytic function of temperature.Comment: 6 pages, no figures, submitted to J Phys A: Math Ge

Metodologia para determinação da zona de abscisão foliar em pomáceas.

Estudos anatômicos e de ontogênese da abscisão foliar em pomáceas são escassos. A queda foliar promovida após formada a zona de abscisão é um processo natural nas pomáceas, e prolonga-se durante o outono, até que ocorram as primeiras geadas no Sul do Brasil. Ainda não se conhece até quando as folhas de macieiras permanecem funcionais. O objetivo deste trabalho foi desenvolver uma metodologia que permita estudar o início e o fi m das zonas de abscisão foliar de macieiras. O trabalho foi realizado nas cultivares Galaxy e Fuji em pomares comerciais de macieira, de Vacaria, Rio Grande do Sul. O método proposto consistiu em coletar,ramos do ano, com 10cm a 20cm de comprimento, e utilizar um segmento contendo uma parte do caule, uma gema axilar e a base do pecíolo, descartando a parte das quatro folhas do ápice. Os segmentos foram fixados, seccionados e corados para a observação da zona de abscisão em microscopia óptica. Os resultados mostraram que a metodologia utilizada permitiu descrever a zona de abscisão em macieiras e que ela é formada por células alongadas com parede celular delgada, apresentando lignifi cação junto à parede celular. O processo manteve a gema intacta e ocorreu no sentido adaxial para o abaxial. A abscisão foliar natural, em plantas de Galaxy e Fuji em sintomas de doença e em condições ambientais favoráveis, pode ser acompanhada 7 e 14 dias antes e depois da colheita, e após, com intervalos de 14 e 21 dias até maio. A partir de maio, as coletas devem ser feitas semanalmente. Essas informações serão úteis na tomada de decisão para realizar práticas culturais e/ou de controle químico, para a manutenção das folhas sadias, resultando no maior acúmulo de reservas de carboidratos e/ou redução do número de aplicações de fungicidas