Velocity Statistics in Holographic Fluids: Magnetized Quark-Gluon Plasma and Superfluid Flow

We study the velocity statistics distribution of an external heavy particle in holographic fluids. We argue that when the dual supergravity background has a finite temperature horizon the velocity statistics goes generically as $1/v$, compatible with the jet-quenching intuition from the quark-gluon plasma. A careful analysis of the behavior of the classical string whose apparent worldsheet horizon deviates from the background horizon reveals that other regimes are possible. We numerically discuss two cases: the magnetized quark-gluon plasma and a model of superfluid flow. We explore a range of parameters in these top-down supergravity solutions including, respectively, the magnetic field and the superfluid velocity. We determine that the velocity statistics goes largely as $1/v$, however, as we leave the non-relativistic regime we observe some deviations.Comment: 32 pages, 12 figures, references added and minor correction

The Holographic Disorder-Driven Superconductor-Metal Transition

We implement the effects of disorder on a holographic superconductor by introducing a random chemical potential on the boundary. We demonstrate explicitly that increasing disorder leads to the formation of islands where the superconducting order is enhanced and subsequently to the transition to a metal. We study the behavior of the superfluid density and of the conductivity as a function of the strength of disorder. We find explanations for various marked features in the conductivities in terms of hydrodynamic quasi-normal modes of the holographic superconductors. These identifications plus a particular disorder-dependent spectral weight shift in the conductivity point to a signature of the Higgs mode in the context of disordered holographic superconductors. We observe that the behavior of the order parameter close to the transition is not mean-field type as in the clean case, rather we find robust agreement with $\exp(- A\, |T-T_c|^{-\nu})$, with $\nu =1.03\pm 0.02$ for this disorder-driven smeared transition.Comment: 7 pages, 8 figures. v2: minor improvements of the Higgs mode and smeared phase transition discussions. Typos corrected. Published versio

A holographic perspective on phonons and pseudo-phonons

We analyze the concomitant spontaneous breaking of translation and conformal symmetries by introducing in a CFT a complex scalar operator that acquires a spatially dependent expectation value. The model, inspired by the holographic Q-lattice, provides a privileged setup to study the emergence of phonons from a spontaneous translational symmetry breaking in a conformal field theory and offers valuable hints for the treatment of phonons in QFT at large. We first analyze the Ward identity structure by means of standard QFT techniques, considering both spontaneous and explicit symmetry breaking. Next, by implementing holographic renormalization, we show that the same set of Ward identities holds in the holographic Q-lattice. Eventually, relying on the holographic and QFT results, we study the correlators realizing the symmetry breaking pattern and how they encode information about the low-energy spectrum.Comment: 31+1 pages, version accepted on JHE

A Dirty Holographic Superconductor

We study the effects of disorder on a holographic superconductor by introducing a random chemical potential on the boundary. We consider various realizations of disorder and find that the critical temperature for superconductivity is enhanced. We also present evidence for a precise form of renormalization in this system. Namely, when the random chemical potential is characterized by a Fourier spectrum of the form $k^{-2\alpha}$ we find that the spectra of the condensate and the charge density are again power-laws, whose exponents are accurately and universally governed by linear functions of $\alpha$.Comment: 5 pages, 8 figures. v3: discussion improved, references added, typos corrected, results unchange

Holographic p-wave Superconductor with Disorder

We implement the effects of disorder on a holographic p-wave superconductor by introducing a random chemical potential which defines the local energy of the charge carriers. Since there are various possibilities for the orientation of the vector order parameter, we explore the behaviour of the condensate in the parallel and perpendicular directions to the introduced disorder. We clarify the nature of various branches representing competing solutions and construct the disordered phase diagram. We find that moderate disorder enhances superconductivity as determined by the value of the condensate. Though we mostly focus on uncorrelated noise, we also consider a disorder characterized by its spectral properties and study in detail its influence on the spectral properties of the condensate and charge density. We find fairly universal responses of the resulting power spectra characterized by linear functions of the disorder power spectrum.Fil: Arean, Daniel. Instituto Max Planck de Física; AlemaniaFil: Pando Zayas, Leopoldo. University of Michigan; Estados UnidosFil: Salazar, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Scardicchio, Antonello. The Abdus Salam. International Centre for Theoretical Physics; Italia. Columbia University; Estados Unidos. Princeton University; Estados Unido

Enfermedades alérgicas como factores asociados al trastorno por déficit de atención con hiperactividad en niños. Hospital Militar Central, 2018 - 2019

Determinar si las enfermedades alérgicas son factores de riesgo asociados para el trastorno por déficit de atención con hiperactividad en niños de 4 a 14 años atendidos por consultorio externo en el servicio de pediatría del Hospital Militar Central-Lima durante los meses de septiembre 2018 a septiembre 2019. Material y Métodos: Se llevó a cabo un estudio de tipo analítico, observacional, retrospectivo, de casos y controles. La población de estudio estuvo constituida por 160 pacientes de 4 a 14 años según criterios de inclusión y exclusión establecidos, distribuidos en dos grupos: con TDAH y sin TDAH. Resultados: El análisis estadístico estableció que las enfermedades alérgicas son factores de riesgo asociados al TDAH (OR: 2.37, IC95%: 1.07-5.20; p<0.05). Siendo la rinitis alérgica (OR: 2.77, IC95%: 1.13-6.82; p<0.05) y la dermatitis atópica (OR: 3.70, IC95%: 1.26-10.87; p<0.05) factores de riesgo asociados al TDAH. El asma (OR: 0.66, IC95%: 0.26-1.66; p>0.05) no es un factor de riesgo asociado al TDAH. Conclusión: Las enfermedades alérgicas son factores de riesgo asociados al trastorno por déficit de atención con hiperactividad en niños de 4 a 14 años en el Hospital Militar Central - LimaTo determine if allergic diseases are associated risk factors for attention deficit hyperactivity disorder in children aged 4 to 14 years attended by an outpatient office in the pediatric department of Central Military Hospital-Lima during the months of September 2018 to September 2019. Material and Methods: An analytical, observational, retrospective, case-control study was carried out. The study population consisted of 160 patients aged 4 to 14 years according to established inclusion and exclusion criteria, distributed in two groups: with ADHD and without ADHD. Results: The statistical analysis established that allergic diseases are a risk factor associated with ADHD (OR: 2.37, 95% CI: 1.07-5.20; p <0.05). Allergic rhinitis (OR: 2.77, 95% CI: 1.13-6.82; p<0.05) and atopic dermatitis (OR: 3.70, 95% CI: 1.2610.87; p0.05) is not a risk factor associated with ADHD. Conclusion: Allergic diseases are a risk factor associated with attention deficit hyperactivity disorder in children aged 4 to 14 years in the Central Military HospitalLimaTesi

Influence of overheating criteria in the appraisal of building fabric performance

In response to the threat of anthropogenic climate change, heating dominated countries have focused on re-ducing the space conditioning demand by increasing insulation and airtightness. However, given climate projec-tions and lifespan of buildings, concerns have arisen on whether these strategies deliver resilient solutions. As overheating can be evaluated through different criteria, this paper investigates if building fabric performance is subject to bias from the assessment method chosen and account for discrepancies between previous studies.To answer this, we modelled dwellings compliant with 1995 and 2006 UK building regulations and the FEES and Passivhaus standards in a consistent and realistic manner. The parametric study included different weathers, thermal mass, glazing ratios, shading strategies, occupancy profiles, infiltration levels, purge ventilation strate-gies and orientations, resulting in 16128 simulation models. To provide confidence in the output, the base model was first validated against data collected from a real well-insulated dwelling.Results show that the benchmark choice is influential in the evaluation of building fabric performance as it is able to inverse overheating trends. Criteria based on adaptive comfort best represented expected behaviour, where improved building fabric is a resilient measure that reduces overheating as long as occupants are able to open windows for ventilation

Holographic disorder driven superconductor-metal transition

We implement the effects of disorder on a holographic superconductor by introducing a random chemical potential on the boundary. We demonstrate explicitly that increasing disorder leads to the formation of islands where the superconducting order is enhanced and subsequently to the transition to a metal. We study the behavior of the superfluid density and of the conductivity as a function of the strength of disorder. We find explanations for various marked features in the conductivities in terms of hydrodynamic quasinormal modes of the holographic superconductors. These identifications plus a particular disorder-dependent spectral weight shift in the conductivity point to a signature of the Higgs mode in the context of disordered holographic superconductors. We observe that the behavior of the order parameter close to the transition is not mean-field type as in the clean case; rather we find robust agreement with exp(-A|T-Tc|-ν), with ν=1.03±0.02 for this disorder-driven smeared transition.Instituto de Física La Plat