Extending canonical Monte Carlo methods II

Previously, we have presented a methodology to extend canonical Monte Carlo methods inspired on a suitable extension of the canonical fluctuation relation $C=\beta^{2}$ compatible with negative heat capacities $C<0$. Now, we improve this methodology by introducing a better treatment of finite size effects affecting the precision of a direct determination of the microcanonical caloric curve $\beta (E) =\partial S(E) /\partial E$, as well as a better implementation of MC schemes. We shall show that despite the modifications considered, the extended canonical MC methods possibility an impressive overcome of the so-called \textit{super-critical slowing down} observed close to the region of a temperature driven first-order phase transition. In this case, the dependence of the decorrelation time $\tau$ with the system size $N$ is reduced from an exponential growth to a weak power-law behavior $\tau(N)\propto N^{\alpha}$, which is shown in the particular case of the 2D seven-state Potts model where the exponent $\alpha=0.14-0.18$.Comment: Version submitted to JSTA

Equilibrium fluctuation theorems compatible with anomalous response

Previously, we have derived a generalization of the canonical fluctuation relation between heat capacity and energy fluctuations $C=\beta^{2}<\delta U^{2}>$, which is able to describe the existence of macrostates with negative heat capacities $C<0$. In this work, we extend our previous results for an equilibrium situation with several control parameters to account for the existence of states with anomalous values in other response functions. Our analysis leads to the derivation of three different equilibrium fluctuation theorems: the \textit{fundamental and the complementary fluctuation theorems}, which represent the generalization of two fluctuation identities already obtained in previous works, and the \textit{associated fluctuation theorem}, a result that has no counterpart in the framework of Boltzmann-Gibbs distributions. These results are applied to study the anomalous susceptibility of a ferromagnetic system, in particular, the case of 2D Ising model.Comment: Extended version of the paper published in JSTA

Understanding critical behavior in the framework of the extended equilibrium fluctuation theorem

Recently (arXiv:0910.2870), we have derived a fluctuation theorem for systems in thermodynamic equilibrium compatible with anomalous response functions, e.g. the existence of states with \textit{negative heat capacities} $C<0$. In this work, we show that the present approach of the fluctuation theory introduces new insights in the understanding of \textit{critical phenomena}. Specifically, the new theorem predicts that the environmental influence can radically affect critical behavior of systems, e.g. to provoke a suppression of the divergence of correlation length $\xi$ and some of its associated phenomena as spontaneous symmetry breaking. Our analysis reveals that while response functions and state equations are \emph{intrinsic properties} for a given system, critical behaviors are always \emph{relative phenomena}, that is, their existence crucially depend on the underlying environmental influence

Mathematical algorithm to transform digital biomass distribution maps into linear programming networks in order to optimize bio-energy delivery chains

Many linear programming models have been developed to model the logistics of bio-energy chains. These models help to determine the best set-up of bio-energy chains. Most of them use network structures built up from nodes with one or more depots, and arcs connecting these depots. Each depot is source of a certain biomass type. Nodes can also be a storage point for a certain biomass type or a production facility (e.g. power plant) where the biomass is used. Arcs represent transport between depots. To be able to combine GIS spatial studies with linear programming models it is necessary to build a network from a digital map. In this work a mathematical calculation method is developed to select the actual points on the map where to collect biomass that will then be considered as biomass sources in a network model

Performing an Environmental Tax Reform in a regional Economy. A Computable General Equilibrium

We use a Computable General Equilibrium model to simulate the effects of an Environmental Tax Reform in a regional economy (Andalusia, Spain).The reform involves imposing a tax on CO2 or SO2 emissions and reducing either the Income Tax or the payroll tax of employers to Social Security, and eventually keeping public deficit unchanged.This approach enables us to test the so-called double dividend hypothesis, which states that this kind of reform is likely to improve both environmental and non-environmental welfare.In the economy under analysis, an employment double dividend arises when the payroll tax is reduced and, if CO2 emissions are selected as environmental target, a (limited) strong double could also be obtained.No double dividend appears when Income Tax is reduced to compensate the environmental tax.environmental tax;general equilibrium;regional economics;tax reform;dividends

Microscopic study of neutron-rich Dysprosium isotopes

Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry based models. Ground-state, gamma and beta-bands, and their B(E2) transition strengths in 160-168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q.Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered whose free parameters, fixed for all members of the chain are used to fine tune the moment of inertia of rotational bands and the band-head of gamma and beta-bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170Dy. The results presented show that it is possible to study full chain of isotopes or isotones in the region with the present model

The Consistency of Rural Development Policies with the Position of the European Union on NTCS

The set of policy tools that the EU puts under the heading of Rural Development is extremely heterogeneous, such heterogeneity translates into a different degree of coupling support with agriculture production and also brings out the need to discuss the actual consistency of such tools with the UE position on NTCs at WTO. Examined in the present work are the Rural Development Plans (RDPs) and the Regional Operative Plans (ROPs) recently approved by the European Commission for the Italian Regions. The analysis is of a purely qualitative type and is based on currently available information, that is, the measures and the relative project typologies approved within the Plans. Taking into account the EU position on NTCs and their relation with multifunctionality we look at the tools applied for Rural Development in Italy with respect to their degree of de-coupling, production of externalities/non marketable goods and consistency with the EU position on NTCs. Financial allotment by measure typology is also examined. We found out that the present set of actions that fall under rural development is still dominated by a sector−based intervention, even in the case of measures aimed at safeguarding the environment, the least contestable ones. Paradoxically, the measures aimed at the promotion of Rural Development and at training, that better respond to the NTC objectives, are those for which the least resources are located.Non trade concerns, multifunctionality, rural development policies., Community/Rural/Urban Development,

Geometrical aspects and connections of the energy-temperature fluctuation relation

Recently, we have derived a generalization of the known canonical fluctuation relation $k_{B}C=\beta^{2}$ between heat capacity $C$ and energy fluctuations, which can account for the existence of macrostates with negative heat capacities $C<0$. In this work, we presented a panoramic overview of direct implications and connections of this fluctuation theorem with other developments of statistical mechanics, such as the extension of canonical Monte Carlo methods, the geometric formulations of fluctuation theory and the relevance of a geometric extension of the Gibbs canonical ensemble that has been recently proposed in the literature.Comment: Version accepted for publication in J. Phys. A: Math and The