Quantum Statistical Relation for black holes in nonlinear electrodynamics coupled to Einstein-Gauss-Bonnet AdS gravity

We consider curvature-squared corrections to Einstein-Hilbert gravity action in the form of Gauss-Bonnet term in D>4 dimensions. In this theory, we study the thermodynamics of charged static black holes with anti-de Sitter (AdS) asymptotics, and whose electric field is described by nonlinear electrodynamics (NED). These objects have received considerable attention in recent literature on gravity/gauge dualities. It is well-known that, within the framework of anti de-Sitter/Conformal Field Theory (AdS/CFT) correspondence, there exists a nonvanishing Casimir contribution to the internal energy of the system, manifested as the vacuum energy for global AdS spacetime in odd dimensions. Because of this reason, we derive a Quantum Statistical Relation directly from the Euclidean action and not from the integration of the First Law of thermodynamics. To this end, we employ a background-independent regularization scheme which consists in the addition to the bulk action of counterterms that depend on both extrinsic and intrinsic curvatures of the boundary (Kounterterm series). This procedure results in a consistent inclusion of the vacuum energy and chemical potential in the thermodynamic description for Einstein-Gauss-Bonnet AdS gravity regardless the explicit form of the NED Lagrangian.Comment: 22 pages, no figures; 3 references and a subsection on Thermodynamic Charges added; Final version for PR

Topological regularization and self-duality in four-dimensional anti-de Sitter gravity

It is shown that the addition of a topological invariant (Gauss-Bonnet term) to the anti-de Sitter (AdS) gravity action in four dimensions recovers the standard regularization given by holographic renormalization procedure. This crucial step makes possible the inclusion of an odd parity invariant (Pontryagin term) whose coupling is fixed by demanding an asymptotic (anti) self-dual condition on the Weyl tensor. This argument allows to find the dual point of the theory where the holographic stress tensor is related to the boundary Cotton tensor as $T_{j}^{i}=\pm (\ell ^{2}/8\pi G)C_{j}^{i}$, which has been observed in recent literature in solitonic solutions and hydrodynamic models. A general procedure to generate the counterterm series for AdS gravity in any even dimension from the corresponding Euler term is also briefly discussed.Comment: 13 pages, no figures; enlarged discussion on self-duality condition for AAdS spacetimes, references added, final version for PR

Conotoxin MI: disulfide bonding and conformational states

Journal ArticleThe toxic peptide from Conus magus venom (conotoxin MI) is a 14-amino acid peptide (McIntosh, M., Cruz, L. J., Hunkapiller, M. W., Gray, W. R., and Olivera, B. M. (1982) Arch. Biochem. Biophys. 218, 329-334) which inhibits the acetylcholine ceptor. In this work we have confirmed the primary structure and established the disulfide bonding configuration (Cys 3-Cys 8; Cys 4-Cys 14) by direct chemical synthesis of the toxin with specific disulfide bridges

Characterization of dispersion strengthened copper with 3wt%Al2O3 by mechanical alloying

The copper matrix has been dispersion strengthened with 3wt. %Al2O3 by mechanical alloying. Commercial alumina powder with an average particle size of 0.751 mum was used for alloying. The mechanical alloying process was performed in a planetary ball mill up to 20h in air. After milling all powders were treated in H-2 at 400(degrees)C for 1h, and finally hot pressing was used for compaction (800degreesC, 3h, Ar). Structure observations revealed a lamellar structure (Al2O3 particles largely restricted to interlamellar planes between adjacent copper lamellae) accompanied also by structure refinement. These structural changes were mostly completed in the early stage of milling, and retained after compaction. Micro. hardness was found to progressively increase with milling time. So, after 5h of milling the micro hardness of the Cu+3twt%Al2O3 compact was 1540MPa, i.e. 2.5 times greater than for the as-received electrolytic copper powder (638MPa) compacted under identical conditions, while after 20h of milling it was 2370 MPa. However, after exposing the tested compact at 800degreesC up to 5h, the achieved hardening effect vanished

Climate change impact on thermal comfort in Mexico City housing

This is the author accepted manuscript. The final version is available from WEENTECH via the DOI in this record4th International Conference on Energy, Environment and Economics (ICEEE2019), 20-22 August 2019, Edinburgh, ScotlandA two storey terraced house was modelled in ESP-r with a simple window opening control strategy to represent typical dwellings found in Mexico City and the adjoining municipalities. Future weather data was generated for years in this century based on morphing methods developed from the literature and by the authors and a TMY weather file developed from historical data between 1975 to 1989 by WhiteBox Technologies. The population in the region under consideration is a little over 20 million which represents 16% of Mexico’s population. The present day climate is such that air conditioning is rarely used in single family housing. The main cooling strategy in the hottest months (Mid February to mid June) is window opening. This was modelled considering that if the interior temperature was at or above 18°C and the exterior air temperature was below the interior air temperature then windows would be open. The air flow was modelled using the flow network model within ESP-r. It was found that in the latter part of the present century, this strategy would become increasingly ineffective. This is likely to lead to a considerable increase in installed air conditioning in single family dwellings and a consequent increase in electricity demand and consumption leading to a need for substantial investments in electricity transmission and distribution systems in the region to bring in power from distant sources.Engineering and Physical Sciences Research Council (EPSRC)CONACYT-SENER-Sustentabilidad Energética fund Mexic

Nova razmatranja malih složenih magnetskih sustava

In this paper, a composed A + B magnetic system, with spins JA = 2 and JB = 3/2, is considered within the mean-field approximation, in the framework of Tsallis nonextensive statistics. Our motivation is twofold: (1) to approach the existing experimental data of manganese oxides (manganites), where Mn3+ and Mn4+ form two magnetic sublattices, and (2) to investigate the structure of nonextensive density matrices of composed systems. By imposing that thermodynamic quantities, such as the magnetization of sublattices A and B, must be invariant whether the calculation is taken over the total Hilbert space or over partial subspaces, we found that the expression for the nonextensive entropy must be adapted. Our argument is supported by the calculation of sublattice magnetizations MA and MB, internal energy, UA and UB and magnetic specific heat, CA and CB. It is shown that only with the modified entropy, the two methods of calculation agree to each other. Internal energy and magnetization are additive, but no clear relationship was found between SA, SB and the total entropy SA+B for q /= 1. It is shown that the reason for the failure of the standard way of calculation is the assumption of statistical independence between the two subsystems, which however does not affect the density matrix in the full Hilbert space.Razmatramo magnetski sustav složen od sastavnica A i B sa spinovima JA = 2 i JB = 3/2 u približenju srednjeg polja i Tsallisove nesveobuhvatne statistike. Dva su povoda: (1) opisati poznate mjerne podatke za manganove okside (manganite), u kojima Mn3+ i Mn4+ tvore dvije magnetske podrešetke, i (2) istražiti strukturu nesveobuhvatne matrice gustoće složenih sustava. Postavljajući da termodinamičke veličine, kao magnetizacija podrešetaka A i B, moraju biti invarijantne kako za račun u cijelom Hilbertovom prostoru, tako i u pojedinim podrešetkama, nalazimo da se izraz za nesveobuhvatnu entropiju mora primijeniti. Naša tvrdnja se zasniva na računu magnetizacije podrešetaka MA i MB, unutarnje energije UA i UB, i magnetske specifične topline, CA i CB. Pokazuje se da su s izmijenjenom entropijom obje metode u skladu. Unutarnja energija i magnetizacija se pribrajaju, ali između SA, SB i ukupne entropije SA+B nismo našli jednostavan odnos za q /= 1. Pokazuje se da je pretpostavka o neovisnosti dvaju podsustava razlog što uobičajen način računanja entropije nije dobar, što ne utječe na račun matrice gustoće u cijelom Hibertovom prostoru

Thermodynamics of Einstein-Born-Infeld black holes with negative cosmological constant

We study the thermodynamics associated to topological black hole solutions of AdS gravity coupled to nonlinear electrodynamics (Born-Infeld) in any dimension, using a background-independent regularization prescription for the Euclidean action given by boundary terms which explicitly depend on the extrinsic curvature (Kounterterms series). A finite action principle leads to the correct definition of thermodynamic variables as Noether charges, which satisfy a Smarr-like relation. In particular, for the odd-dimensional case, a consistent thermodynamic description is achieved if the internal energy of the system includes the vacuum energy for AdS spacetime.Comment: 29 pages, no figures; additional comments on extreme black hole case, a few references added; final version for PR