Thermodynamics of noncommutative quantum Kerr black holes

Thermodynamic formalism for rotating black holes, characterized by noncommutative and quantum corrections, is constructed. From a fundamental thermodynamic relation, equations of state and thermodynamic response functions are explicitly given and the effect of noncommutativity and quantum correction is discussed. It is shown that the well known divergence exhibited in specific heat is not removed by any of these corrections. However, regions of thermodynamic stability are affected by noncommutativity, increasing the available states for which some thermodynamic stability conditions are satisfied.Comment: 16 pages, 9 figure

Functional Optimization in Complex Excitable Networks

We study the effect of varying wiring in excitable random networks in which connection weights change with activity to mold local resistance or facilitation due to fatigue. Dynamic attractors, corresponding to patterns of activity, are then easily destabilized according to three main modes, including one in which the activity shows chaotic hopping among the patterns. We describe phase transitions to this regime, and show a monotonous dependence of critical parameters on the heterogeneity of the wiring distribution. Such correlation between topology and functionality implies, in particular, that tasks which require unstable behavior --such as pattern recognition, family discrimination and categorization-- can be most efficiently performed on highly heterogeneous networks. It also follows a possible explanation for the abundance in nature of scale--free network topologies.Comment: 7 pages, 3 figure

Perturbation theory for very long-range potentials

Systems with very long-range interactions (that decay at large distances like $U(r)\sim r^{-l}$ with $l\le d$ where $d$ is the space dimensionality) are difficult to study by conventional statistical mechanics perturbation methods. Examples of these systems are gravitational and charged (non-electroneutral). In this work we propose two alternative methodologies to avoid these difficulties and capture some of the properties of the original potential. The first one consists in expressing the original potential in terms of a finite sum of hard-core Yukawa potentials. In the second one, the potential is rewritten as a damped potential, using a damping function with a parameter that controls the range of the interaction. These new potentials, which mimic the original one, can now be treated by conventional statistical mechanics methods.Comment: 25 pages, 11 figure

Deformed Phase Space in Cosmology and Black Holes

It is well known that one way to study canonical quantum cosmology is through the Wheeler DeWitt (WDW) equation where the quantization is performed on the minisuperspace variables. The original ideas of a deformed minisuperspace were done in connection with noncommutative cosmology, by introducing a deformation into the minisuperspace in order to incorporate an effective noncommutativity. Therefore, studying solutions to Cosmological models through the WDW equation with deformed phase space could be interpreted as studying quantum effects to Cosmology. In this chapter, we make an analysis of scalar field cosmology and conclude that under a phase space transformation and imposed restriction, the effective cosmological constant is positive. On the other hand, obtaining the wave equation for the noncommutativity Kantowski-Sachs model, we are able to derive a modified noncommutative version of the entropy. To that purpose, the Feynman-Hibbs procedure is considered in order to calculate the partition function of the system

Microplásticos e imposex en el caracol marino Thaisella chocolata procedente de la costa central marina del Perú

Contamination by microplastics (MP) and the presence of imposex (IMP) in snails for human consumption has become an issue of global concern in marine ecosystems. The objective of this study was to evaluate the presence of MP and IMP in the sea snail Thaisella chocolata in four locations and two seasons of the year on the central coast of Peru. The selected sites were the coves of Chorrillos and Cerro Azul, and the minor seaports of Chancay and Huacho, in the department of Lima, Peru. Individuals of T. chocolata were collected in each location and in two seasons of 2021. The snails were examined for the quantification of MP, according to their shape and color, and in the females, the IMP was determined and qualified as a percentage. The global analysis shows a Frequency of Occurrence (FO%) of MP of was 97.86% ± 3.34 (range from 90.90 to 100%), and the abundance (MP microparticles/individual) was 9.07 ± 4.71 (range 4.72 to 17.82). The colors of the black, blue and magenta MPs were the dominant ones. The FO%, and the abundance of MP microparticles did not show differences between both seasons. The highest MP detection values occurred in individuals from Cerro Azul. The MP micro-fragments presented the highest abundance and the black color was the dominant one. The IMP was rated as high in 50% of the female snails. No differ­ences were observed in FO% or in the abundance of MP microparticles between seasons. The IMP was not associated with the FO% or with the abundance of MP in T. chocolata. The abundance of MP in T. chocolata was negatively related to nitrites, nitrates, and ammonium, and positively related to dissolved oxygen in seawater. The findings indicate that the marine snail T. chocolata is a suitable organism for monitoring MP and IMP contamination.La contaminación por microplásticos (MP) y por la presencia de imposex (IMP) en caracoles de consumo humano se ha convertido en un tema de preocupación mundial en los ecosistemas marinos. El objetivo del presente estudio fue evaluar la presencia de MP y de IMP en el caracol marino Thaisella chocolata en cuatro localidades y dos temporadas del año de la costa central del Perú. Los sitios seleccionados fueron las caletas de Chorrillos, y de Cerro Azul, y los puertos marítimos menores de Chancay y de Huacho, del departamento de Lima, Perú. Individuos de T. chocolata fueron colectados en cada localidad y en dos temporadas del 2021. Los caracoles fueron examinados para la cuantificación de MP, de acuerdo a su forma y coloración, y en las hembras fue determinado el IMP y calificado porcentualmente. El análisis global muestra una Frecuencia de Ocurrencia (FO%) de MP de 97,86% ± 3,34 (rango de 90,90 al 100%), y la abundancia (micropartículas de MP/individuo) fue de 9,07 ± 4,71 (rango 4,72 a 17,82). Los colores de los MP negro, azul y magenta fueron los dominantes. La FO%, y la abundancia de micropartículas de MP no mostraron diferencias entre ambas temporadas. Los mayores valores de detección de MP ocurrieron en los individuos de Cerro Azul. Los microfragmentos de MP presentaron las mayores abundancias y el color negro fue el dominante. El IMP fue calificado mayormente como alto en un 50% de los caracoles hembras. No se observaron diferencias en la FO% ni en la abundancia de micropartículas de MP entre temporadas. El IMP no se asoció con la FO% ni con la abundancia de MP en T. chocolata. La abundancia de MP en T. chocolata se relacionó negativamente con los nitritos, nitratos, y amonio, y positivamente con el oxígeno disuelto del agua de mar. Los hallazgos indican que el carac

Goldsmithing traditions and innovations in colonial Colombia: an analytical study of crucibles from Santa Cruz de Mompox

© 2019, © Society for Post-Medieval Archaeology 2019. SUMMARY: The 16th-century Spanish conquest of Colombia brought new technologies that altered and interacted with native metalworking traditions. In the colonial village of Santa Cruz de Mompox, renowned because of its goldsmithing tradition, indigenous groups and Spaniards experienced momentous encounters of individuals, metallurgical technologies and knowledge. However, little is known concerning colonial metallurgy, its continuities and changes with regards to the pre-Columbian period. Here we present the analytical characterization of five crucibles recovered in Mompox, together with discussion of relevant archival evidence. We find evidence for the local manufacture of crucibles as well as for the melting of unrefined gold dust, tumbaga (gold-copper-silver alloys) and silver. These metallurgical practices illustrate some likely illegal activities, continuities with pre-Columbian traditions in the use of tumbagas, and the Spanish-led introduction of silver in northern Colombia. It is argued that metallurgical remains can be informative of wider social and economic negotiations that engaged indigenous peoples, mestizos and Spaniards, which are critical to understand the configuration of the colonial reality