Entropy in higher-curvature theories of gravity

A presente tese estuda a noción de entropía gravitacional cando a acción da teoría presenta correccións de orde superior na curvatura en dous contextos diferentes. Por una banda, mediante a entropía dos buracos negros nunha familia de teorías que presenta invariancia baixo T-dualidade a nivel das solucións clásicas. O obxectivo nesta parte é precisamente estudar a interrelación entre a entropía e a Tdualidade, comprobando se estas transformacións deixan ou non invariantes as propiedades termodinámicas dos buracos negros. Por outra banda, estúdase tamén a entropía de entrelazamento holográfica cando aparecen termos de orde superior na curvatura. Logo de propoñer unha reescritura do correspondente funcional máis sinxela e práctica, probando a súa equivalencia coa versión previamente coñecida na literatura, obtéñense os funcionáis para diversas teorías, e utilízanse para calcular os termos universais correspondentes a diferentes rexións na teoría de campos conforme (CFT) dual

Association of benzodiazepines, opioids and tricyclic antidepressants use and falls in trauma patients: Conditional effect of age

Introduction The relationship between benzodiazepines, opioids and tricyclic antidepressants and trauma is of great importance because of increased consumption and the growing evidence of a positive association among older adults. The objective of this study was to determine the effect size of the association between the consumption of psychotropic medications /opioids and falls in patients who have suffered trauma by studying the role of other variables in this relationship. Method From 2011 to 2016, the presence of benzodiazepines, opioids and tricyclic antidepressants and other drugs in 1060 patients admitted for trauma at a level I trauma hospital was analysed. Multivariate models were used to measure the adjusted effect size of the association between consumption of benzodiazepines, opioids and tricyclic antidepressants and falls, and the effect of age on this association was studied. Results A total of 192 patients tested positive for benzodiazepines, opioids and tricyclic antidepressants, with same-level falls being the most frequent mechanism of injury in this group (40.1%), with an odds ratio of 1.96 (1.40–2.75), p < 0.001. Once other covariates were introduced, this association was not observed, leaving only age, gender (woman) and, to a lesser extent, sensory conditions as variables associated with falls. Age acted as an effect modifier between benzodiazepines, opioids and tricyclic antidepressants and falls, with significant effect sizes starting at 51.9 years of age. Conclusions The association between the consumption of benzodiazepines, opioids and tricyclic antidepressants and falls in patients admitted for trauma is conditioned by other confounding variables, with age being the most influential confounding variable.The members of the GISyC group (SCG, CFA and ESM) are funded by “Programa Operativo FEDER Extremadura (2014-2020) y Fondo Europeo Desarrollo Regional (FEDER) Grant number: GR18146. This work was supported by 4IE+ project (0499_4IE_PLUS_4_E) funded by the Interreg V-A España-Portugal (POCTEP) 2014- 2020 program

Holographic entanglement entropy for perturbative higher-curvature gravities

The holographic entanglement entropy functional for higher-curvature gravities involves a weighted sum whose evaluation, beyond quadratic order, requires a complicated theory-dependent splitting of the Riemann tensor components. Using the splittings of general relativity one can obtain unambiguous formulas perturbatively valid for general higher-curvature gravities. Within this setup, we perform a novel rewriting of the functional which gets rid of the weighted sum. The formula is particularly neat for general cubic and quartic theories, and we use it to explicitly evaluate the corresponding functionals. In the case of Lovelock theories, we find that the anomaly term can be written in terms of the exponential of a differential operator. We also show that order-n densities involving nR Riemann tensors (combined with n − nR Ricci’s) give rise to terms with up to 2nR − 2 extrinsic curvatures. In particular, densities built from arbitrary Ricci curvatures combined with zero or one Riemann tensors have no anomaly term in their functionals. Finally, we apply our results for cubic gravities to the evaluation of universal terms coming from various symmetric regions in general dimensions. In particular, we show that the universal function characteristic of corner regions in d = 3 gets modified in its functional dependence on the opening angle with respect to the Einstein gravity resultPB and JC were supported by the Simons Foundation through the “It From Qubit” Simons collaboration. The work of AVL is supported by the Spanish MECD fellowship FPU16/06675, and by MINECO FPA2017-84436-P, Xunta de Galicia ED431C 2017/07, Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2019-2022) and the European Union (European Regional Development Fund-ERDF), “María de Maeztu” Units of Excellence MDM-2016-0692, and the Spanish Research State AgencyS

Entanglement entropy in cubic gravitational theories

We derive the holographic entanglement entropy functional for a generic gravitational theory whose action contains terms up to cubic order in the Riemann tensor, and in any dimension. This is the simplest case for which the so-called splitting problem manifests itself, and we explicitly show that the two common splittings present in the literature — minimal and non-minimal — produce different functionals. We apply our results to the particular examples of a boundary disk and a boundary strip in a state dual to 4- dimensional Poincaré AdS in Einsteinian Cubic Gravity, obtaining the bulk entanglement surface for both functionals and finding that causal wedge inclusion is respected for both splittings and a wide range of values of the cubic couplingS

Aspects of N-partite information in conformal field theories

We present several new results for the $N$-partite information, $I_N$, of spatial regions in the ground state of $d$-dimensional conformal field theories. First, we show that $I_N$ can be written in terms of a single $N$-point function of twist operators. Using this, we argue that in the limit in which all mutual separations are much greater than the regions sizes, the $N$-partite information scales as $I_N \sim r^{-2N\Delta}$, where $r$ is the typical distance between pairs of regions and $\Delta$ is the lowest primary scaling dimension. In the case of spherical entangling surfaces, we obtain a completely explicit formula for the $I_4$ in terms of 2-, 3- and 4-point functions of the lowest-dimensional primary. Then, we consider a three-dimensional scalar field in the lattice. We verify the predicted long-distance scaling and provide strong evidence that $I_N$ is always positive for general regions and arbitrary $N$ for that theory. For the $I_4$, we find excellent numerical agreement between our general formula and the lattice result for disk regions. We also perform lattice calculations of the mutual information for more general regions and general separations both for a free scalar and a free fermion, and conjecture that, normalized by the corresponding disk entanglement entropy coefficients, the scalar result is always greater than the fermion one. Finally, we verify explicitly the equality between the $N$-partite information of bulk and boundary fields in holographic theories for spherical entangling surfaces in general dimensions.Comment: 39 pages + appendices, 12 figure

T-duality equivalences beyond string theory

We examine a two parameter family of gravitational actions which contains higher-derivative terms. These are such that the entire action is invariant under corrected T-duality rules, which we derive explicitly. Generically this action does not describe low energy string backgrounds except for isolated choices for the parameters. Nevertheless, we demonstrate that in this theory the entropy and the temperature of generic non-extremal black hole solutions are T-duality invariant. This further supports the idea put forward in our previous work that T-duality might provide physical equivalences beyond the realm of string theoryWe are grateful to Ted Jacobson, Eric Lescano, Diego Marqués, Sudipta Sarkar and Yuji Tachikawa for fruitful discussions. The work of J.D.E. is supported by the Ministry of Science grant FPA2017-84436-P, Xunta de Galicia ED431C 2017/07, FEDER, and the María de Maeztu Unit of Excellence MDM-2016-0692. He wishes to thank Pontificia Universidad Católica de Valparaíso and Universidad Adolfo Ibáñez for hospitality, during the visit funded by CONICYT MEC 80150093. He is also thankful to the Physics Department of the University of Buenos Aires, where part of this work was done under the support of the Milstein program. J.A.S.-G. acknowledges support from CUAASC grant of Chulalongkorn University and Spanish FPI fellowship from FEDER grant FPA-2011-22594. A.V.L. is supported by the Spanish MECD fellowship FPU16/06675.S

T-duality and high-derivative gravity theories: the BTZ black hole/string paradigm

We show that the temperature and entropy of a BTZ black hole are invariant under T-duality to next to leading order in M ⋆− 2, M⋆ being the scale suppressing higher-curvature/derivative terms in the Lagrangian. We work in the framework of a twoparameter family of theories exhibiting T-duality, which includes (but goes beyond) String Theory. Interestingly enough, the AdS/CFT correspondence enforces quantization conditions on these parameters. In the particular case of bosonic/heterotic string theory, our results extend those of a classical paper by Horowitz and Welch. For generic (albeit quantized) values of the parameters, it suggests that T-duality might be an interesting tool to constrain consistent low-energy effective actions while entailing physical equivalences outside String Theory. Moreover, it generates a new family of regular asymptotically flat black string solutions in three-dimensionsThe work of J.D.E. is supported by MINECO FPA2014-52218, Xunta de Galicia ED431C 2017/07, FEDER, and the María de Maeztu Unit of Excellence MDM-2016-0692. He wishes to thank Pontificia Universidad Católica de Valparaíso and Universidad Adolfo Ibáñez for hospitality, during the visit funded by CONICYT MEC 80150093. He is also thankful to the Physics Department of the University of Buenos Aires, where part of this work was done under the support of the Milstein program. J.A.S.-G. acknowledges support from CUAASC grant of Chulalongkorn University and Spanish FPI fellowship from FEDER grant FPA2011-22594. A.V.L. is supported by the Spanish MECD fellowship FPU16/06675S

Efecto de las drogas alucinógenas, estimulantes y depresoras del sistema nervioso central sobre la gravedad de la lesión en pacientes ingresados por traumatismos

Objective: The effect of drugs other than alcohol on severity of trauma remains unclear. Pooled data analyses in previous studies that grouped substances with opposite effects on the central nervous system (CNS) may have masked the influence of substances on injury severity. The aim was to analyze the effect of stimulant, hallucinogenic and depressant drugs other than alcohol on injury severity in trauma patients. Methods: The presence of alcohol, stimulant drugs (cocaine, amphetamines and methamphetamines), depressant drugs (benzodiazepines, opiates, methadone and barbiturates) and hallucinogenic drugs (THC and PCP) was analyzed in 1187 patients between 16 and 70 years old admitted to a trauma hospital between November 2012 and June 2015. Injury severity was determined prospectively as the Injury Severity Score. A multivariate analysis was used to quantify the strength of association between exposure to substances and trauma severity, using the presence of alcohol as a stratification variable. Results: Drugs other than alcohol were found in 371 patients (31.3%): 32 (2.7%) stimulants, 186 (15.3%) depressants, 78 (6.6%) hallucinogenics and 75 (5.6%) polydrug use. The presence of CNS depressant substances was associated with increased injury severity only in patients also exposed to alcohol, with an adjusted odds ratio of 4.63 (1.37-15.60) for moderate injuries and 7.83 (2.53-24.21) for severe. Conclusion: CNS depressant drugs had a strong influence on injury severity in patients who screened positive for alcohol consumption.Objetivo: No está claro qué efecto tienen las drogas distintas del alcohol sobre la gravedad de los traumatismos. Los análisis incluidos en estudios previos, que agrupan sustancias con efectos opuestos sobre el sistema nervioso central (SNC), pueden haber enmascarado la influencia de estas sobre la gravedad. El objetivo fue analizar el efecto de las drogas alucinógenas, estimulantes y depresoras del SNC, diferentes del alcohol, sobre la gravedad de las lesiones en pacientes ingresados por traumatismos. Métodos: Se analizó la presencia de alcohol, drogas estimulantes (cocaína, anfetaminas y metanfetaminas), depresoras (benzodiacepinas, opiáceos, metadona y barbitúricos) y alucinógenas (THC y PCP) en 1187 pacientes de entre 16 y 70 años de edad ingresados por traumatismo de noviembre de 2012 a junio de 2015. La gravedad del traumatismo se determinó prospectivamente mediante la Injury Severity Score. Se cuantificó la fuerza de la asociación entre la exposición a sustancias y la gravedad del traumatismo mediante un análisis multivariante, utilizando la presencia de alcohol como variable de estratificación. Conclusión: Las drogas depresoras del SNC tuvieron una fuerte influencia en la gravedad del traumatismo en los pacientes que además presentaban resultados positivos para consumo de alcohol.This work was supported by the Dirección General de Tráfico, Spain [No. 0100DGT22389] and the Consejería de Salud, Junta de Andalucía, Spain [No. PI-0691-2013]

Electrochemical oxidation of lignin for the simultaneous production of bioadhesive precursors and value-added chemicals

Electrochemical oxidation of lignin has been widely regarded as a clean and reliable alternative to obtain value-added products from lignin, such as vanillin or guaiacol. This work aims to go one step beyond the production of low molecular weight molecules and explore the possibility of using lignin residues from electrochemical treatments in the context of biorefinery. To this end, a two-way valorization of lignin by electrochemical oxidation is proposed, in order to obtain a liquid phase enriched in low molecular weight organic oligomers and a solid phase of modified lignin to be used as bioadhesive precursor. Hydroxylation of lignin by electrochemical oxidation using boron-doped diamond (BDD) anodes was observed according to the FTIR and MALDI-TOF results, concluding that an applied current density of 10 mA cm−2 leads to promising modifications for the formulation of bioadhesives. Furthermore, NIPU bioadhesives with electrochemically modified lignin were successfully prepared and tested for use in particleboard panels, showing satisfactory mechanical properties, and thus paving the way for more environmentally friendly lignin modification procedures for the wood industryJJC acknowledges financial support from Galician Government though a postdoctoral fellowship (ED481B-2021/015). SG-R and GE predoctoral and postdoctoral fellowships (BES-2017-081677 and RYC-2018-024846-I, respectively) were funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future”. JJC, SG-R, TAL-C, GE and MTM belong to the Galician Competitive Research Group (GRC) ED431C-2021/37. LERMAB is financed by the French Agence Nationale de la Recherche (ANR) as part of the laboratory of excellence (LABEX) ARBRE. The authors would also like to thank the use of the analytical facilities of IR-Raman Spectroscopy Unit and Mass Spectrometry Unit from RIAIDT-USC.S