Correlation functions in scalar field theory at large charge

We compute general higher-point functions in the sector of large charge operators ϕn,ϕ¯¯¯n at large charge in O(2) (ϕ¯¯¯ϕ)2 theory. We find that there is a special class of "extremal" correlators having only one insertion of ϕ¯¯¯n that have a remarkably simple form in the double-scaling limit n →∞ at fixed g n2 ≡ λ, where g ~ ϵ is the coupling at the O(2) Wilson-Fisher fixed point in 4 − ϵ dimensions. In this limit, also non-extremal correlators can be computed. As an example, we give the complete formula for ⟨ϕ(x1)nϕ(x2)nϕ¯¯¯(x3)nϕ¯¯¯(x4)n⟩, which reveals an interesting structure

Strategies of employer branding with temporary workers: Possibilities and obstacles towards their integration as branding ambassadors

This study analyses temporary employees’ perceptions and experiences with respect to temporary employment companies (TECs), which contract them, and to the companies where they provide their services. Their level of possible integration in the strategies of employer branding in both types of companies is analysed. To that end, both the causes for their satisfaction or dissatisfaction with those companies have been studied and the temporary employee Net Promoter Score (eNPS) has been analysed in order to determine to what extent they may act as a company branding ambassador. This analysis has been carried out on the basis of two investigations conducted among employees from the same TEC before and after the Covid-19 pandemics, which has allowed us to count on a series of values to identify trends and, at the same time, to ascertain their impact on this type of employees caused by such a dramatic and global event as the recent pandemics started in 2020. With this in mind, we have reached a set of conclusions on how to improve the integration of this type of workers in companies through the improvement of internal communication and the strengthening of the corporative culture to foster their role as branding ambassadors in the companies where they operate.El trabajo analiza las percepciones y experiencias de los empleados temporales respecto a las empresas de trabajo temporal que los contratan y respecto a las empresas en las que prestan sus servicios. Se analiza el nivel de su posible integración en las estrategias de employer branding de ambos tipos de empresa. Para ello, se han estudiado las causas de su satisfacción o insatisfacción con las compañías y se ha analizado el eNPS (employer Net Promoter Score) del trabajador temporal para determinar en qué medida puede actuar como embajador de la marca de las empresas. Este análisis se ha llevado a cabo a partir de dos investigaciones realizadas entre trabajadores de la misma empresa de trabajo temporal antes y después de la pandemia de la Covid-19, lo que nos ha permitido contar con una serie de valores para determinar tendencias y, al mismo tiempo, conocer el impacto en este tipo de trabajadores de una circunstancia tan dramática y global como la reciente pandemia que empezó en 2020. A partir de ello hemos obtenido una serie de conclusiones sobre cómo optimizar la integración de este tipo de trabajadores en las empresas, a través de la mejora de la comunicación interna y el fortalecimiento de la cultura corporativa, para favorecer así su papel como embajadores de la marca de las compañías en las que desarrollan su labor

MINLP-based hybrid strategy for operating mode selection of TES-backed-up refrigeration systems

Es la versión aceptada del artículo. Se puede consultar la versión final en https://onlinelibrary.wiley.com/doi/10.1002/rnc.4674This brief deals with the satisfaction of the daily cooling demand by a hybrid system that consists of a vapor-compression refrigeration cycle and a thermal energy storage (TES) unit, based on phase change materials. The addition of the TES tank to the original refrigeration plant allows to schedule the cooling production regardless of the instantaneous demand, given that the TES tank can store cold energy and release it whenever deemed appropriate. The scheduling problem is posed as an optimization problem based on mixed-integer nonlinear programming (MINLP) since it includes both discrete and continuous variables. The latter corresponds to the references on the main cooling powers involved in the problem (cooling production at the evaporator and TES charging/discharging), whereas the discrete variables define the operating mode scheduling. Therefore, in addition to the hybrid features of the physical plant, a hybrid optimal control strategy is also proposed. A receding horizon approach is applied, similar to model predictive control (MPC) strategies, while economic criteria are imposed in the objective function, as well as feasibility issues. The TES state estimation is also addressed since its instantaneous charge ratio is not measurable. The proposed strategy is applied in simulation to a challenging cooling demand profile, and the main advantages of the MINLP-based strategy over a nonlinear MPC-based scheduling strategy previously developed are highlighted, regarding operating cost, ease of tuning, and ability to adapt to cooling demand variations.Ministerio de Ciencia e InnovaciónFCT (Portugal)POR Lisbo

Primordial black holes and gravitational waves from dissipation during inflation

We study the generation of a localized peak in the primordial spectrum of curvature perturbations from a transient dissipative phase during inflation, leading to a large population of primordial black holes. The enhancement of the power spectrum occurs due to stochastic thermal noise sourcing curvature fluctuations. We solve the stochastic system of Einstein equations for many realizations of the noise and obtain the distribution for the curvature power spectrum. We then propose a method to find its expectation value using a deterministic system of differential equations. In addition, we find a single stochastic equation whose analytic solution helps to understand the main features of the spectrum. Finally, we derive a complete expression and a numerical estimate for the energy density of the stochastic background of gravitational waves induced at second order in perturbation theory. This includes the gravitational waves induced during inflation, during the subsequent radiation epoch and their mixing. Our scenario provides a novel way of generating primordial black hole dark matter with a peaked mass distribution and a detectable stochastic background of gravitational waves from inflation.Comment: 48 pages, 11 figures; matches published version in JCAP; typo corrected, the rest of the paper is unchange

Well-being of suckling calves under two different rearing systems: case study in the central milk basin of Argentina

En el presente trabajo se llevo a cabo un estudio de caso con enfoque cuantitativo. El objetivo de este estudio fue evaluar el bienestar en teneros lechales durante la época invernal bajo dos diferentes sistemas de crianza, que se utilizan en la zona. Los terneros, se alojaron en dos sistemas: en estaca los machos y en jaula las hembras. Los animales recibieron dos tomas diarias de leche (4 l/día), balanceado iniciador y agua ad libitum. Se registraron pesos iníciales y finales. La ganancia de peso se analizó mediante técnicas estadísticas descriptivas. Se tomaron muestra de saliva para determinar cortisol (CS) en cuatro momentos del día. Los datos fueron analizados para detectar variaciones horarias. El CS no mostró fluctuaciones diarias. Durante quince días y día por medio, se registraron las conductas: parado, echado, comiendo y otras. La metodología de observación y registro utilizada fue el muestreo de barrido a intervalos regulares. Los datos de analizaron con la prueba del c2. El efecto tratamiento fue significativo sobre el comportamiento (p<0,01). Los animales de los dos sistemas gastaron el 50% del tiempo en la conducta de reposo.Well-being of suckling calves under two different rearing systems. Case study in the central milk basin of Argentina. In this paper we conducted a case study with quantitative approach. The aim of this study was to assess welfare in suckling calves during the winter season under two different rearing systems, which are used in the area. Calves were housed in two systems: a stake in males and females cage. All animals received 4 L milk per day, in two servings. Water and a commercial starter were offered ad libitum. Initial and final weights were recorded, weight gain was analyzed using descriptive statistical techniques. Saliva samples were taken at four times over the day, to analyze saliva cortisol (SC). Data were analyzed for time variations. Neither daily fluctuations in SC concentrations nor system effects were detected in SC concentrations. Different behaviors: standing, lying, eating and "others" were observed every other day over a fortnight. Scan sampling at regular intervals was utilized. Data were analyzed by a c2 test. Systems effects were observed on behavioral conducts (p<0.01). Animals in both systems spent 50% of their time lying.Fil: Leva, Paula Edit. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: García, M. S.. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Toffoli Arnaudo, Guillermo Daniel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodríguez, A. G.. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Rey, Florencia. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Higher prevalence of X-ray selected AGN in intermediate age galaxies up to z~1

We analyse the stellar populations in the host galaxies of 53 X-ray selected optically dull active galactic nuclei (AGN) at 0.34<z<1.07 with ultra-deep (m=26.5) optical medium-band (R~50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows us to consistently measure the strength of the 4000 AA break, Dn(4000), a reliable age indicator for stellar populations. We confirm that most X-ray selected moderate-luminosity AGN (L_X<10^44 erg/s) are hosted by massive galaxies (typically M*>10^10.5 M_sun) and that the observed fraction of galaxies hosting an AGN increases with the stellar mass. A careful selection of random control samples of inactive galaxies allows us to remove the stellar mass and redshift dependencies of the AGN fraction to explore trends with several stellar age indicators. We find no significant differences in the distribution of the rest-frame U-V colour for AGN hosts and inactive galaxies, in agreement with previous results. However, we find significantly shallower 4000 AA breaks in AGN hosts, indicative of younger stellar populations. With the help of a model-independent determination of the extinction, we obtain extinction-corrected U-V colours and light-weighted average stellar ages. We find that AGN hosts have younger stellar populations and higher extinction compared to inactive galaxies with the same stellar mass and at the same redshift. We find a highly significant excess of AGN hosts with Dn(4000)~1.4 and light weighted average stellar ages of 300-500 Myr, as well as a deficit of AGN in intrinsic red galaxies. We interpret failure in recognising these trends in previous studies as a consequence of the balancing effect in observed colours of the age-extinction degeneracy.Comment: Accepted for publication in MNRAS, 12 pages, 8 figures, 1 tabl

Operator mixing in large N superconformal field theories on S^4 and correlators with Wilson loops

We find a general formula for the operator mixing on the S4 of chiral primary operators for the N=4 theory at large N in terms of Chebyshev polynomials. As an application, we compute the correlator of a chiral primary operator and a Wilson loop, reproducing an earlier result by Giombi and Pestun obtained from a two-matrix model proposal. Finally, we discuss a simple method to obtain correlators in general N=2 superconformal field theories in perturbation theory in terms of correlators of the N=4 theory

Non-Stick Coatings in Aluminium Molds for the Production of Polyurethane Foam

The manufacturing of polyurethane foam is a process of great industrial importance in the automotive and furniture sector. The operation of demolding is the most delicate, since the foam sticks firmly to the walls of the mold onto which it has spread. In order to avoid the use of demolding agents, the proposal is to coat the inside of the molds with non-stick coatings. In this work, three types of different coatings were studied: fluoropolymers, ceramics, and elastomers. After carrying out different tests in the laboratory, two fluoropolymer coatings (PFA (perfluoroalkoxy) and PTFE (polytetrafluoroethylene)) were selected for a test at the industrial level and, after 1500 cycles of demolding, it was experimentally proven that the PFA coating is the most adequate for the use studie

Large N correlation functions in superconformal field theories

We compute correlation functions of chiral primary operators in N=2 super-conformal theories at large N using a construction based on supersymmetric localization recently developed by Gerchkovitz et al. We focus on N=4 SYM as well as on supercon-formal QCD. In the case of N=4 we recover the free field theory results as expected due to non-renormalization theorems. In the case of superconformal QCD we study the planar expansion in the large N limit. The final correlators admit a simple generalization to a finite N formula which exactly matches the various small N results in the literature

Water-Repellent Fluoropolymer-Based Coatings

We would like to thank to the company TECNIMACOR S.L. (Córdoba, Spain) for the preparation of the coatings studied in this work.Fluoropolymer-based coatings are widely used for release applications. However, these hydrophobic surfaces do not reveal a significantly low adhesion. Water repellency incorporated to fluoropolymer coatings might enhance their release performance. In this work, we focused on the surface texturing of a well-known polytetrafluoroethylene (PTFE)-based coating. We explored as texturing routes: sanding, sandblasting and laser ablation. We examined the surface roughness with white light confocal microscopy and the surface morphology with environmental scanning electron microscopy (ESEM). Water-repellent fluoropolymer coatings were reproduced in all cases, although with different degree, parametrized with bounces of water drops (4–5 μL). Laser ablation enabled the lowest adhesion of coatings with 24 ± 2 bounces. This result and the current development of laser patterning for industry assure the incipient use of laser ablation for release coatings.The research was funded by the projects MAT2014-60615-R and MAT2017-82182-R, funded by the Spanish Ministry of Economy and Competitiveness (MINECO-FEDER)