Exploiting Resolution-based Representations for MaxSAT Solving

Most recent MaxSAT algorithms rely on a succession of calls to a SAT solver in order to find an optimal solution. In particular, several algorithms take advantage of the ability of SAT solvers to identify unsatisfiable subformulas. Usually, these MaxSAT algorithms perform better when small unsatisfiable subformulas are found early. However, this is not the case in many problem instances, since the whole formula is given to the SAT solver in each call. In this paper, we propose to partition the MaxSAT formula using a resolution-based graph representation. Partitions are then iteratively joined by using a proximity measure extracted from the graph representation of the formula. The algorithm ends when only one partition remains and the optimal solution is found. Experimental results show that this new approach further enhances a state of the art MaxSAT solver to optimally solve a larger set of industrial problem instances

Hidrolisado de peixe causa alterações nas características microbiológicas e químicas de substrato.

O hidrolisado de peixe é um fertilizante orgânico obtido da fermentação de resíduos do processamento de pescados marinhos. O presente estudo avaliou os efeitos do hidrolisado de peixe em características microbiológicas e químicas de substrato à base de casca de pinus e solo, em microcosmos. O hidrolisado de peixe estimulou a comunidade de Trichoderma, aumentou a liberação de amônia e aumentou a condutividade elétrica do substrato de forma proporcional à sua concentração no substrato esterilizado e no não esterilizado. O hidrolisado não interferiu nas comunidades de Bacillus, de Pseudomonas e de Fusarium oxysporum f.sp. lycopersici. Também não foram verificadas alterações significativas no pH e na concentração de nitrato do substrato

Algebraic Bethe ansatz approach for the one-dimensional Hubbard model

We formulate in terms of the quantum inverse scattering method the algebraic Bethe ansatz solution of the one-dimensional Hubbard model. The method developed is based on a new set of commutation relations which encodes a hidden symmetry of 6-vertex type.Comment: appendix additioned with Boltzmann weigths and R-matrix. Version to be published in J.Phys.A:math.Gen. (1997

Simulations of a mortality plateau in the sexual Penna model for biological ageing

The Penna model is a strategy to simulate the genetic dynamics of age-structured populations, in which the individuals genomes are represented by bit-strings. It provides a simple metaphor for the evolutionary process in terms of the mutation accumulation theory. In its original version, an individual dies due to inherited diseases when its current number of accumulated mutations, n, reaches a threshold value, T. Since the number of accumulated diseases increases with age, the probability to die is zero for very young ages (n = T). Here, instead of using a step function to determine the genetic death age, we test several other functions that may or may not slightly increase the death probability at young ages (n < T), but that decreases this probability at old ones. Our purpose is to study the oldest old effect, that is, a plateau in the mortality curves at advanced ages. Imposing certain conditions, it has been possible to obtain a clear plateau using the Penna model. However, a more realistic one appears when a modified version, that keeps the population size fixed without fluctuations, is used. We also find a relation between the birth rate, the age-structure of the population and the death probability.Comment: submitted to Phys. Rev.

Jordan-Wigner fermionization for the one-dimensional Bariev model of three coupled XY chains

The Jordan-Wigner fermionization for the one-dimensional Bariev model of three coupled XY chains is formulated. The Lax operator in terms of fermion operators and the quantum R-matrix are presented explicitly. Furthermore, the graded reflection equations and their solutions are discussed.Comment: 10 pages, no figur

A possible origin of superconducting currents in cosmic strings

The scattering and capture of right-handed neutrinos by an Abelian cosmic string in the SO(10) grand unification model are considered. The scattering cross-section of neutrinos per unit length due to the interaction with the gauge and Higgs fields of the string is much larger in its scaling regime than in the friction one because of the larger infrared cutoff of the former.The probability of capture in a zero mode of the string accompanied by the emission of a gauge or Higgs boson shows a resonant peak for neutrino momentum of the order of its mass. Considering the decrease of number of strings per unit comoving volume in the scaling epoch the cosmological consequences of the superconducting strings formed in this regime will be much smaller than those which could be produced already in the friction one.Comment: 14 pages Latex, 4 figues/ep

A variational approach for the Quantum Inverse Scattering Method

We introduce a variational approach for the Quantum Inverse Scattering Method to exactly solve a class of Hamiltonians via Bethe ansatz methods. We undertake this in a manner which does not rely on any prior knowledge of integrability through the existence of a set of conserved operators. The procedure is conducted in the framework of Hamiltonians describing the crossover between the low-temperature phenomena of superconductivity, in the Bardeen-Cooper-Schrieffer (BCS) theory, and Bose-Einstein condensation (BEC). The Hamiltonians considered describe systems with interacting Cooper pairs and a bosonic degree of freedom. We obtain general exact solvability requirements which include seven subcases which have previously appeared in the literature.Comment: 18 pages, no eps figure

Removal of Diclofenac by constructed wetlands planted with Phragmites australis and Typha spp.

In the modern society, an ever increasing number of pharmaceutical active compounds (PhACs) is used for the treatment and prevention of various diseases. Ingested drugs are only partially absorbed by the organisms and studies have shown that the excreted compounds are only partially removed in the sewage treatment plants (STPs) [1]. Diclofenac is a non-steroidal anti-inflammatory drug taken to reduce inflammation and as an analgesic reducing pain in certain conditions. In several studies, it was detected in surface water, thus indicating incomplete degradability of this substance in STPs. Despite the low concentrations detected (ng/L - μg/L), those studies have shown damaging effects of this and other pharmaceutical compounds on the aquatic ecosystems [2]. Subsurface flow constructed wetland systems (SSFs) are low cost wastewater treatment systems, usually used to provide a form of secondary or tertiary treatment for wastewaters. Depuration in SSFs is achieved by the concerted action between plant rhizomes, microorganisms and the support matrix components. SSFs’ efficiency can be significantly improved by optimization of the operation conditions which is achieved by careful selection of the support matrices, plants and microorganisms used. The aim of the present work was to evaluate the efficiency of SSF microcosms planted with Phragmites australis and Typha spp plants, to remove diclofenac from contaminated water. The wastewater samples were collected from a STP located in Évora-Portugal. In order to optimize the role played by the support matrix, light expanded aggregates (LECA) and cork, a very common material in Alentejo, were tested. Two different assays were performed, in winter and summer time, using doped wastewater, to evaluate the removal rates of diclofenac by the SSF systems. The quantification of diclofenac was achieved using HPLC-UV with a reversed phase column. [3]. The study results show that constructed wetlands can be an alternative system for removing diclofenac from contaminated water. REFERENCES [1] Fent, K., Weston, A. N., and Caminada, D., Aquatic Toxic. 76 (2006) 122. [2] Maurer, M., Escher, B.I., Richle, P., Schaffner, C., and Alder, A.C., Water Research 41 (2007) 1614. [3] Dordio A., Pinto J., Dias C., Pinto A.P., Carvalho A., Teixeira D.M., International Journal of Environmental Analytical Chemistry, 89 (2009) 835