Search

Context. In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with the general aim of delivering stellar parameters and elemental abundances for large samples of Galactic stars, complementing Gaia astrometry. Among those surveys, the Gaia-ESO Public Spectroscopic Survey, the only one performed on a 8m class telescope, was designed to target 100 000 stars using FLAMES on the ESO VLT (both Giraffe and UVES spectrographs), covering all the Milky Way populations, with a special focus on open star clusters. Aims. This article provides an overview of the survey implementation (observations, data quality, analysis and its success, data products, and releases), of the open cluster survey, of the science results and potential, and of the survey legacy. A companion article reviews the overall survey motivation, strategy, Giraffe pipeline data reduction, organisation, and workflow. Methods. We made use of the information recorded and archived in the observing blocks; during the observing runs; in a number of relevant documents; in the spectra and master catalogue of spectra; in the parameters delivered by the analysis nodes and the working groups; in the final catalogue; and in the science papers. Based on these sources, we critically analyse and discuss the output and products of the Survey, including science highlights. We also determined the average metallicities of the open clusters observed as science targets and of a sample of clusters whose spectra were retrieved from the ESO archive. Results. The Gaia-ESO Survey has determined homogeneous good-quality radial velocities and stellar parameters for a large fraction of its more than 110 000 unique target stars. Elemental abundances were derived for up to 31 elements for targets observed with UVES. Lithium abundances are delivered for about 1/3 of the sample. The analysis and homogenisation strategies have proven to be successful; several science topics have been addressed by t

We report the synthesis of a dibenzodinaphthocoronene (DBDNC) derivative as a novel nanographene with armchair, zigzag, and fjord edges, which was characterized by NMR and X-ray crystallography as well as infrared (IR) and Raman spectroscopies. Ultrafast transient absorption (TA) spectroscopy revealed the presence of stimulated emission signals at 655 nm and 710 nm with a relatively long lifetime, which resulted in dual amplified spontaneous emission (ASE) bands under ns-pulsed excitation, indicating the promise of DBNDC as a near-infrared (NIR) fluorophore for photonics. Our results provide new insight into the design of nanographene with intriguing optical properties by incorporating fjord edges.

Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars and star clusters, extending across a very wide range of abundances and ages. This provides a legacy data set of intrinsic value, and equally a large wide-ranging dataset that is of value for the homogenisation of other and future stellar surveys and Gaia's astrophysical parameters. Aims. This article provides an overview of the survey methodology, the scientific aims, and the implementation, including a description of the data processing for the GIRAFFE spectra. A companion paper introduces the survey results. Methods. Gaia-ESO aspires to quantify both random and systematic contributions to measurement uncertainties. Thus, all available spectroscopic analysis techniques are utilised, each spectrum being analysed by up to several different analysis pipelines, with considerable effort being made to homogenise and calibrate the resulting parameters. We describe here the sequence of activities up to delivery of processed data products to the ESO Science Archive Facility for open use. Results. The Gaia-ESO Survey obtained 202 000 spectra of 115 000 stars using 340 allocated VLT nights between December 2011 and January 2018 from GIRAFFE and UVES. Conclusions. The full consistently reduced final data set of spectra was released through the ESO Science Archive Facility in late 2020, with the full astrophysical parameters sets following in 2022. A companion article reviews the survey implementation, scientific highlights, the open cluster survey, and data products.

La presente experiencia educativa tiene por objetivo fomentar el aprendizaje de materiales porosos en asignaturas de Ciencia de Materiales de grados de ciencia e ingeniería a través de la transformación de una tecnología TIC como la impresión 3D en tecnologías propias de la sociedad del conocimiento (TACs - Tecnologías para el Aprendizaje y el Conocimiento) para favorecer nuevas posibilidades educativas de aprendizaje y formación. Los autores presentan una metodología para implementar la herramienta de impresión 3D con el objetivo de fabricar de forma rápida y con bajo coste diversos materiales porosos para su estudio en modalidades organizativas de clases prácticas. La evaluación de la experiencia se realizó mediante encuestas de satisfacción utilizando tres instrumentos: i) cuestionarios anónimos realizados al alumnado mediante la plataforma Kahoot; ii) cuestionarios al profesorado implicado; y iii) cuestionarios a personal externo. La experiencia, desarrollada con un total de 22 estudiantes voluntarios y organizada por 3 profesores y una investigadora posdoctoral, ha resultado motivadora para todos los participantes y representa un avance docente ya que no existe actualmente ningún trabajo en la literatura internacional sobre la caracterización fluidodinámica de materiales macroporosos en prácticas de laboratorio para cursos de universidad. El profesorado externo consultado apunta consideraciones a tener en cuenta sobre la facilidad de implementación de los resultados de esta experiencia educativa.

The main purpose of this suite is Planning and Management of Seismic Emergencies before and after future damaging earthquake. This tool is written in ArcGIS software executing a fast and efficient determination of the estimated shakemaps and damage scenarios. The tool allows to select the earthquake source parameters through a defined database; moreover ground motion prediction equations can be chosen and they can be combined according to the study area features. The local site effects are characterized from Vs30 values, which have been achieved by topographic slope as a proxy (even with local correlations) obtained from digital elevation model. The elements exposed to risk are incorporated from the cadastral database after inputs has been refined through an automated analysis. Vulnerability and estimated losses can be determined either empirically (EMS-98 scale and Vulnerability Index, Iv) or analytically (Capacity spectrum). Additionally, a vulnerability modifier is implemented to account soil-structure resonance. Epistemic uncertainties are quantified in the input parameters using a logic tree. This tool has been validated through a representative seismic scenario: the 1910 Adra earthquake (southern Spain) with moment magnitude (Mw) 6.3 and macroseismic intensity VIII (EMS-98 scale) proving the reliability of this program.

Low-temperature scanning tunneling microscopy is used here to study the dynamic bonding of gold atoms on surfaces under low coordination conditions. In the experiments, using an atomically sharp gold tip, a gold adatom is deposited onto a gold surface with atomic precision either on the first hollow site near a step edge or far away from it. Classical molecular dynamics simulations at 4.2 K and density-functional theory calculations serve to elucidate the difference in the bonding behavior between these two different placements, while also providing information on the crystalline classification of the STM tips based on their experimental performance.

In this work we derive the Bekenstein-Hawking entropy formula, S=A4l2p, from the following minimal assumptions: (i) there is a minimum area, Amin, proportional to l2p; (ii) the event horizon area, A, is tessellated by N=A/Amin distinguishable units; and (iii) the internal structure of these units is that of an infinite tower of internal levels. Although our results are model independent, this internal structure can be realized as the excitations of more fundamental entities such as, for instance, strings or loop quantum gravity spin networks. Even more, once the microstates of the black hole are taken to be singlets formed within the infinite tower of states describing the whole event horizon, the correction term −32logA emerges from our model. Finally, some comments regarding the applicability of the present model to extremal black holes, as well as possible relationships with spectral geometry and other approaches are pointed out. Our results are independent of the dimension of the black hole and whether it is rotating or not.

After evaporation of the organic solvents, benzene, toluene, and cyclohexane on gold substrates, Scanning Tunneling Microscope (STM) shows the presence of a remaining adsorbed layer. The different solvent molecules were individually observed at ambient conditions, and their electronic transport properties characterized through the STM in the Break Junction approach. The combination of both techniques reveals, on one hand, that solvents are not fully evaporated over the gold electrode and, secondly, characterize the electronic transport of the solvents in molecular electronics.

We have carried out the synthesis of two dithia[9]helicenes by means of a LED-based double photocyclization. The compounds have sulfur atoms placed at the terminal rings of the helicene, and they display two alternative C2-symmetrical arrangements named exo (1) and endo (2). Separation of enantiomers of opposite helicity allowed the complete characterization of their chiroptical properties in solution, in silico, by X-ray crystallography, and adsorbed on gold. The theoretical analysis confirms the unexpected finding that endo-dithia[9]helicene displays an experimental dissymmetry factor in CPL (glum) larger than its isomer, exo-dithia[9]helicene. This enhanced glum factor ranks among the largest for a helicene-type molecule. Comparison with smaller analogues, namely exo and endo-dithia[7]helicenes (10 and 11, respectively), is also presented.

Weather forecasts affect many persons’ lives and are used by the general public on a daily basis. However, they are not perfect, and there is an uncertainty associated with the current weather forecasts; users should be aware of this uncertainty. Previous research analyzes the perceptions, uses, and interpretations of uncertainty of Spanish undergraduate students. This study continues with this research line, but we investigate the degree of confidence and communication preferences of students enrolled in three meteorology-related subjects taught at two universities in Spain. We evaluated to what extent students trust in the current weather forecasts and analyzed how students are aware of the uncertainty associated with the forecasts considering different lead times. In addition, we assessed how students value the forecast of several weather elements as well as the students’ preferences for deterministic versus nondeterministic forecasts under two weather situations, with different degree of complexity in the forecast communication. A Google Form questionnaire was developed to address these issues. The survey was conducted in 2018/19, and 101 participants anonymously filled out the survey. Participants were enrolled in three different subjects taught in the degree in marine sciences at the University of Alicante and the degrees in environmental sciences and physics at the University of Valencia. Results show that students have a well-formed opinion of weather forecasts, both for confidence and in relation to the trend found in the current weather forecasts toward less accurate forecasts for larger lead times. For students’ preferences for deterministic versus nondeterministic forecasts, a significant majority of participants prefer weather forecasts that incorporate some uncertainty; a minority prefer single-valued (deterministic) forecasts. In comparing our results with those found in previous studies in different countries and contexts, similar outcomes are observ

In this work we consider a generalized Bronnikov-Ellis wormhole and the tideless Morris-Thorne wormhole and we study the propagation of massive scalar fields. We calculate the quasinormal frequencies using the Wentzel-Kramers-Brillouin method and the pseudospectral Chebyshev method and we show the presence of an anomalous decay rate for the quasinormal modes in the generalized Bronnikov-Ellis wormhole. However, such anomalous behavior is avoided for the fundamental mode in the Morris-Thorne wormhole background.

The generation of amino acid homochirality in prebiotic atmosphere conditions, is a relevant issue in the study of the origin of life. This research is based on the production of amino acids via Strecker synthesis and how it is adjusted to the Kondepudi - Nelson autocatalytic model. The spontaneous mirror symmetry breaking (SMSB) of the new Kondepudi-Nelson-Strecker model, subject to two modifications of (with Limited Enantioselective and Cross Inhibition) and also their combination were studied using stoichiometric network analysis (SNA). In the calculations, the values obtained from the literature for Alanine were considered. A total production of Alanine of 7.56 × 109 mol y-1 was determined under prebiotic atmosphere conditions and starting from that value, the reaction rates for the models studied were estimated. Only the Model with cross inhibition or achiral dimer formation is driven by stochastic fluctuations during SMSB. The stochastic fluctuation was estimated for a value of 2.619 × 10-15 mol L-1. This perturbation was sufficient to trigger SMSB. Finally, the results of SMSB were used to calculate the entropy production for the cross inhibition model.

Las estrellas masivas son el motor químico y mecánico de la evolución galáctica. Una característica de estas estrellas es su multiplicidad. La mayoría, sino todas, nacen en sistemas binarios o de mayor orden y las interacciones con la(s) compañera(s) ocurren para aproximadamente el 70% de las estrellas masivas. Estas interacciones resultan en importantes desviaciones del camino evolutivo estándar. Por tanto, ningún estudio de dichas estrellas estaría completo sin tener en cuenta los efectos de la multiplicidad. Este trabajo de tesis representa los primeros pasos del proyecto MONOS en el que tratamos de una forma homogénea y consistente el estudio de las estrellas tipo O binarias en el hemisferio norte. Para lograr este objetivo se han realizado diversas campañas observaciones en observatorios de primer nivel y empleado diferentes técnicas (Espectroscopía, Lucky Imaging, Lucky spectroscopy y Fotometría). Se presenta el estudio astrométrcio y la clasificación espectral de los 92 sistemas con órbitas publicadas y la revisión de los parámetros orbitales de los 35 sistemas SB1 (de los cuales 8 se ha demostrado que no lo son).

Los compuestos orgánicos conjugados han sido investigados ampliamente debido a su versatilidad para integrarse con otros materiales a través de métodos de bajo coste y a su idoneidad para una amplia gama de aplicaciones optoelectrónicas; por ejemplo, transistores de efecto de campo, células solares, LEDs y láseres, entre otros. Actualmente existe un interés particular en los materiales orgánicos para láser promovido por el desarrollo de aplicaciones biomédicas y de telecomunicaciones. De hecho, el desarrollo de técnicas bottom-up en la síntesis orgánica y de métodos computacionales químico-cuánticos permiten el diseño inteligente de compuestos orgánicos con propiedades a medida que pueden ser beneficiosas para tales aplicaciones. En este sentido, comprender la relación entre las características estructurales de los compuestos orgánicos y sus propiedades optoelectrónicas es una etapa obligatoria en el proceso de diseño. En el desarrollo de esta tesis se evalúan las propiedades fotofísicas de dos familias de compuestos orgánicos –perilenodiimidas y nanografenos– dispersos en matrices inertes con el objetivo de mejorar su funcionamiento como materiales activos para láseres. En particular, se han llevado a cabo tres actuaciones: 1) la investigación sistemática de dos polímeros termoplásticos comerciales, poliestireno y polimetilmetacrilato, como matrices inertes para dispersar compuestos de perilenodiimida con un enfoque en optimizar las propiedades de la guía de ondas y reducir los requisitos de energéticos de los dispositivos; 2) conocer los mecanismos de fotodegradación y quenching de la fotoluminiscencia en derivados de perilenodiimida dispersos en películas de poliestireno con el objetivo de obtener dispositivos más duraderos y eficientes; y 3) estudiar las propiedades fotofísicas de compuestos novedosos de la familia de los nanografenos dispersos en matrices inertes con el fin de comprender la relación entre su estructura –borde, heteroátomos, sustituyentes– y su

En esta tesis exploramos las posibilidades que ofrecen sistemas basados en grafeno como soporte para tecnologías cuánticas. En particular estudiamos en profundidad las bicapas de grafeno en las que se depositan átomos de hidrógeno. Este tipo de defectos crean momentos magnéticos electrónicos localizados alrededor de los adátomos. Los adátomos de hidrógeno proporcionan a su vez el momento magnético nuclear del protón de su núcleo que interacciona con los momentos magnéticos electrónicos. El Hamiltoniano efectivo de este sistema comprende una multitud de términos que, cuando se combinan adecuadamente, pueden dar lugar a fases tanto débil como fuertemente correlacionadas. Las interacciones de Hamiltoniano efectivo pueden ser controladas a través de dos mecanismos. El primero, la ubicación de los defectos introducidos que puede ser elegida con precisión atómica usando STM. El segundo se basa en la apertura controlada de un gap en la estructura de bandas de las bicapas de localización/descolocación de los estados electrónicos depende fuertemente de la cercanía en energía de estados localizados, por lo que la apertura de un gap permite controlar la extensión de los electrones y su interacción con los defectos. Esta plataforma permitiría realizar experimentalmente un gran número de Hamiltonianos que a día de hoy carecen de realización experimental eligiendo la combinación correcta de parámetros entre los defectos y campo eléctrico (o lo que es lo mismo, extensión de los estados electrónicos).

El presente estudio evalúa cómo el alumnado de la Universidad de Alicante interpreta el grado de incertidumbre asociado a las predicciones meteorológicas de viento y precipitación. En primer lugar, se ha comprobado la respuesta del alumnado ante la predicción determinista de la velocidad del viento y la cantidad de precipitación. En segundo lugar, se ha evaluado si el alumnado toma alguna medida ante distintas situaciones de riesgo relacionadas con dichos parámetros, tanto cuando la información se presenta en términos deterministas como de probabilidad. Los resultados indican que un pequeño porcentaje del alumnado espera pronósticos perfectos, mientras que la mayoría reconoce cierto grado de incertidumbre inherente a los pronósticos meteorológicos. En este sentido, el alumnado espera una desviación de ±5-10 km/h para la velocidad del viento, y de ±30 mm para el caso de la cantidad de precipitación. Por otro lado, el alumnado tomaría acciones de precaución ante situaciones de riesgo por fenómenos extremos de viento y precipitación, si bien hay una mayor variedad de respuestas en relación a cuándo y cómo el alumnado tomaría una acción determinada para la predicción de estos mismos parámetros meteorológicos expresados en términos de probabilidad.

Las dificultades en la comprensión de los conceptos necesarios para la correcta interpretación de la relación estructura-propiedades en los materiales compuestos en estudiantes de las asignaturas de “Sólidos Inorgánicos” (2º curso del Grado en Química), “Ciencia de los Materiales” (4º curso del Grado en Química) y “Ciencia de Materiales” (4º curso del Grado en Física) de la Universidad de Alicante, han supuesto el foco de atención para los participantes del presente proyecto. En la red INTERMAT X (red de investigación INTERdisciplinar en MATeriales), se evaluó la posibilidad de incorporar dichos conceptos, hasta ahora impartidos únicamente en clases teóricas, a la enseñanza experimental mediante el diseño y puesta en marcha de unas prácticas de laboratorio. En estas se plantea la utilización de la tecnología de impresión 3D para la fabricación y caracterización mecánica de materiales compuestos junto con la simulación computacional como apoyo conceptual. Los resultados de la experiencia indicaron un alto grado de éxito, observándose un aumento del aprendizaje, y por tanto, del rendimiento académico del estudiantado. La experiencia educativa, con un 33% de carácter presencial y un 67% de carácter virtual, resultó ser una alternativa a las prácticas convencionales de alta presencialidad para su implementación en épocas de pandemia.

For the past three decades nanoscience has widely affected many areas in physics, chemistry and engineering, and has led to numerous fundamental discoveries, as well as applications and products. Concurrently, quantum science and technology has developed into a cross-disciplinary research endeavour connecting these same areas and holds burgeoning commercial promise. Although quantum physics dictates the behaviour of nanoscale objects, quantum coherence, which is central to quantum information, communication and sensing, has not played an explicit role in much of nanoscience. This Review describes fundamental principles and practical applications of quantum coherence in nanoscale systems, a research area we call quantum-coherent nanoscience. We structure this Review according to specific degrees of freedom that can be quantum-coherently controlled in a given nanoscale system, such as charge, spin, mechanical motion and photons. We review the current state of the art and focus on outstanding challenges and opportunities unlocked by the merging of nanoscience and coherent quantum operations.

The interactions of the spins of single atoms with a substrate can be controlled via the moiré lattice created by depositing a 2D material on top of the substrate.

A naphtho[2,1-b:6,5-b′]difuran derivative was found to serve as an effective violet-emitting laser dye. It showed amplified spontaneous emission at 413 nm with the threshold of 1.1–2.9 mJ cm−2 using 0.1–0.5 wt% in polystyrene film. Lasing was also demonstrated using all-polymeric distributed-feedback lasers emitting at 411–417 nm with the threshold of 2.0–2.9 mJ cm−2.

The molecule N,N′-bis(3-methylphenyl)-N,N′-dyphenylbenzidine (TPD) has been widely used in optoelectronic applications, mainly for its hole-transporting properties, but also for its capability to emit blue light and amplified spontaneous emission, which is important for the development of organic lasers. Here, we report deep-blue-emitting distributed feedback (DFB) lasers based on TPD dispersed in polystyrene (PS), as active media, and dichromated gelatin layers with holographically engraved relief gratings, as laser resonators. The effect of the device architecture (with the resonator located below or on top of the active layer) is investigated with a dye (TPD) that can be doped into PS at higher rates (up to 60 wt%), than with previously used dyes (<5 wt%). This has enabled changing the index contrast between film and resonator, which has an important effect on the laser performance. With regards to thresholds, both architectures behave similarly for TPD concentrations above 20 wt%, while for lower concentrations, top-layer resonator devices show lower values (around half). Remarkably, the operational durability of top-layer resonator devices is larger (in a factor of around 2), independently of the TPD concentration. This is a consequence of the protection offered by the resonator against dye photo-oxidation when the device is illuminated with pulsed UV light.

En este estudio cuantitativo se evalúa cómo el alumnado de la Universidad de Alicante interpreta el grado de incertidumbre asociado a las predicciones meteorológicas de viento y precipitación. Para ello, se ha diseñado un cuestionario que incluye 8 preguntas que han sido respondidas por un total de 71 alumnos de grado y máster. En primer lugar, se ha comprobado la respuesta del alumnado ante la predicción determinista de la velocidad del viento y la cantidad de precipitación. En segundo lugar, se ha evaluado si el alumnado toma alguna medida ante distintas situaciones de riesgo relacionadas con dichos parámetros, tanto cuando la información es presentada en términos deterministas como cuando se presenta en términos de probabilidad. Los resultados indican que un pequeño porcentaje del alumnado espera pronósticos perfectos, mientras que la mayoría reconoce cierto grado de incertidumbre inherente a los pronósticos meteorológicos. En este sentido, el alumnado espera una desviación de ±5-10 km/h para la velocidad del viento, y de ±30 mm para el caso de la cantidad de precipitación. Así mismo, el alumnado tomaría acciones de precaución ante situaciones de riesgo por fenómenos extremos de viento y precipitación, aunque hay una mayor variedad de respuestas en cuanto a la probabilidad a la cual se tomaría una acción determinada para la predicción probabilística de estos parámetros meteorológicos.

Fractionalization is a phenomenon in which strong interactions in a quantum system drive the emergence of excitations with quantum numbers that are absent in the building blocks. Outstanding examples are excitations with charge e/3 in the fractional quantum Hall effect1,2, solitons in one-dimensional conducting polymers3,4 and Majorana states in topological superconductors5. Fractionalization is also predicted to manifest itself in low-dimensional quantum magnets, such as one-dimensional antiferromagnetic S = 1 chains. The fundamental features of this system are gapped excitations in the bulk6 and, remarkably, S = 1/2 edge states at the chain termini7,8,9, leading to a four-fold degenerate ground state that reflects the underlying symmetry-protected topological order10,11. Here, we use on-surface synthesis12 to fabricate one-dimensional spin chains that contain the S = 1 polycyclic aromatic hydrocarbon triangulene as the building block. Using scanning tunnelling microscopy and spectroscopy at 4.5 K, we probe length-dependent magnetic excitations at the atomic scale in both open-ended and cyclic spin chains, and directly observe gapped spin excitations and fractional edge states therein. Exact diagonalization calculations provide conclusive evidence that the spin chains are described by the S = 1 bilinear-biquadratic Hamiltonian in the Haldane symmetry-protected topological phase. Our results open a bottom-up approach to study strongly correlated phases in purely organic materials, with the potential for the realization of measurement-based quantum computation13.

Los materiales compuestos constituyen un bloque temático importante en las asignaturas Sólidos Inorgánicos (Grado en Química) y Ciencia de los Materiales (Grado en Química y Grado en Física) impartidas en la Universidad de Alicante. En los últimos años, el profesorado responsable de dichas asignaturas ha constatado que los estudiantes presentan dificultades en la comprensión del temario relacionado con los materiales compuestos y sus propiedades mecánicas. Hasta el momento, el desarrollo de dichos conceptos se había visto limitado a clases teóricas ya que no había sido posible trabajar con materiales compuestos en el laboratorio por su laboriosa fabricación y elevado coste de adquisición. Estas dificultades han motivado el desarrollo del presente trabajo, cuyo objetivo es el de aumentar el aprendizaje del estudiantado mediante: i) la utilización de herramientas de impresión 3D para la fabricación rápida y de bajo coste de materiales compuestos, ii) la predicción de sus propiedades mecánicas por simulación, y iii) su caracterización mecánica en el laboratorio. La experiencia, de carácter principalmente virtual, se realizó con estudiantes voluntarios y su evaluación se llevó a cabo mediante cuestionarios y encuestas de satisfacción. Además de representar una alternativa a las prácticas de laboratorio convencionales que requieren elevada presencialidad en épocas de pandemia, la experiencia ha fomentado el aprendizaje de los estudiantes.

Recently, it has been claimed by J. Harada [Phys. Rev. D 103, L121502 (2021) that the Cotton tensor can describe the effects of gravity beyond general relativity. In this short comment, we show that the Cotton tensor is already present in general relativity. Moreover, we show that Harada’s proposal is equivalent to general relativity concerning the equation of motion both for the sources and for the trace-free part of the curvature. In essence, what remains completely free in Harada’s theory are the field equations relating the part of the curvature which is locally determined by the energy-momentum distribution.

The spectral overlap between stimulated emission (SE) and absorption from dark states (i.e. charges and triplets) especially in the near-infrared (NIR), represents one of the most effective gain loss channel in organic semiconductors. Recently, bottom-up synthesis of atomically precise graphene nanostructures, or nanographenes (NGs), has opened a new route for the development of environmentally and chemically stable materials with optical gain properties. However, also in this case, the interplay between gain and absorption losses has hindered the attainment of efficient lasing action in the NIR. Here, we demonstrate that the introduction of two fluoranthene imide groups to the NG core leads to a more red-shifted emission than the precursor NG molecule (685 vs. 615 nm) and also with a larger Stokes (45 nm vs. 2 nm, 1026 cm-1 vs. 53 cm-1, respectively). Photophysical results indicate that, besides the minimisation of ground state absorption losses, such substitution permits to suppress the detrimental excited state absorption in the NIR, which likely arises from a dark state with charge-transfer character. This has enabled NIR lasing (720 nm) from all-solution processed distributed feedback devices with one order of magnitude lower thresholds than those of previously reported NIR-emitting NGs. This study represents an advance in the field of NGs and, in general, organic semiconductors photonics, towards the development of cheap and stable NIR lasers.

The M4F project brings together the fusion and fission materials communities working on the prediction of radiation damage production and evolution and its effects on the mechanical behaviour of irradiated ferritic/martensitic (F/M) steels. It is a multidisciplinary project in which several different experimental and computational materials science tools are integrated to understand and model the complex phenomena associated with the formation and evolution of irradiation induced defects and their effects on the macroscopic behaviour of the target materials. In particular the project focuses on two specific aspects: (1) To develop physical understanding and predictive models of the origin and consequences of localised deformation under irradiation in F/M steels; (2) To develop good practices and possibly advance towards the definition of protocols for the use of ion irradiation as a tool to evaluate radiation effects on materials. Nineteen modelling codes across different scales are being used and developed and an experimental validation programme based on the examination of materials irradiated with neutrons and ions is being carried out. The project enters now its 4th year and is close to delivering high-quality results. This paper overviews the work performed so far within the project, highlighting its impact for fission and fusion materials science.

After 15 yr, in late 2018, the magnetar XTE J1810−197 underwent a second recorded X-ray outburst event and reactivated as a radio pulsar. We initiated an X-ray monitoring campaign to follow the timing and spectral evolution of the magnetar as its flux decays using Swift, XMM–Newton, NuSTAR, and NICER observations. During the year-long campaign, the magnetar reproduced similar behaviour to that found for the first outburst, with a factor of 2 change in its spin-down rate from ∼7.2 × 10−12 to ∼1.5 × 10−11 s s−1 after two months. Unique to this outburst, we confirm the peculiar energy-dependent phase shift of the pulse profile. Following the initial outburst, the spectrum of XTE J1810−197 is well modelled by multiple blackbody components corresponding to a pair of non-concentric, hot thermal caps surrounded by a cooler one, superposed to the colder star surface. We model the energy-dependent pulse profile to constrain the viewing and surface emission geometry and find that the overall geometry of XTE J1810−197 has likely evolved relative to that found for the 2003 event.

Perylenediimide (PDI) compounds with no substituents in their core are widely used as the active units of thin-film organic lasers. Recently, bay-substituted PDIs (b-PDIs) bearing two sterically hindering diphenylphenoxy groups at the 1,7-bay positions have received great attention because they show red-shifted emission with respect to bay-unsubstituted PDIs, while maintaining high photoluminescence (PL) quantum yields and low amplified spontaneous emission (ASE) thresholds even at high doping rates. However, their ASE photostability is relatively low compared to that of state-of-the-art PDIs. Thus, the design of b-PDIs with improved ASE photostability remains a challenge. Here, the synthesis of two b-PDIs with phenyl-type substituents at the imide positions is reported. Complete characterization of their optical properties, including absorption, PL, ASE, and transient spectroscopy, supported also by quantum chemical calculations, is performed with the dyes diluted in either a liquid solvent or a polystyrene film. Film experiments were accomplished at very low doping rates, to resemble the isolated molecule behavior, and also in a range of increasing doping rates, to investigate concentration quenching effects. The reported b-PDIs show improved ASE photostability (3-fold) with respect to b-PDIs with aliphatic-type substituents at the imide positions, whilst they show more propensity toward aggregation.

The characterization of multiplicity of high-mass stars is of fundamental importance to understand their evolution, the diversity of observed core-collapse supernovae and the formation of gravitational wave progenitor systems. Despite that, until recently, one of the final phases of massive star evolution – the cool supergiant phase – has received comparatively little attention. In this study, we aim to explore the multiplicity among the cool supergiant (CSG) population in the Large and Small Magellanic Clouds (LMC and SMC, respectively). To do this we compile extensive archival radial velocity (RV) measurements for over 1000 CSGs from the LMC and SMC, spanning a baseline of over 40 yr. By statistically correcting the RV measurements of each stellar catalogue to the Gaia DR2 reference frame we are able to effectively compare these diverse observations. We identify 45 CSGs where RV variations cannot be explained through intrinsic variability, and are hence considered binary systems. We obtain a minimum binary fraction of 15±4 per cent for the SMC and of 14±5 per cent for the LMC, restricting our sample to objects with at least 6 and 5 observational epochs, respectively. Combining these results, we determine a minimum binary fraction of 15±3 per cent for CSGs. These results are in good agreement with previous results which apply a correction to account for observational biases. These results add strength to the hypothesis that the binary fraction of CSGs is significantly lower than their main-sequence counterparts. Going forward, we stress the need for long-baseline multi-epoch spectroscopic surveys to cover the full parameter space of CSG binary systems.

Context. Many galaxies host pronounced circumnuclear starbursts, fuelled by infalling gas. Such activity is expected to drive the secular evolution of the nucleus and generate super winds which enrich the interstellar and intergalactic medium. Moreover, given the intense radiation fields and extreme gas and cosmic ray densities present within such regions, one might question whether star formation proceeds in a different manner to that occurring in more quiescent regions of the galactic disc, potentially leading to a dependence of the stellar initial mass function on the local environment. Aims. To address the physics of circumnuclear starbursts, we are driven to observe the centre of our own Galaxy, which is the only example where individual stars may be resolved. Previous studies have revealed a rich population of very massive stars, found in three young massive clusters as well as being distributed, in apparent isolation, throughout the inner ∼500 pc of the Galaxy. In this paper we investigate the size and composition of the latter cohort in order to constrain its origin and role in the lifecycle of the Galactic Centre. Methods. To accomplish this, we utilised the Very Large Telescope + K-band Multi-Object Spectrograph to obtain homogeneous, high signal-to-noise ratio observations of known and candidate massive stars suitable for spectral classification and quantitative analysis. Results. We identified 17 new isolated massive stars and reclassified a further 19 known examples, leading to a total of at least 83 within the Galactic Centre. Due to the selection criteria employed, these were strongly biased towards stars with powerful stellar winds and/or extensive circumstellar envelopes; as such, we suspect the resultant census to be incomplete. No further stellar clusters, or their tidally stripped remnants, were identified, although an apparent overdensity of very young and massive stars is found to be coincident with the Sgr B1 star forming region. Conclusions.

Simulating the long-term evolution of temperature and magnetic fields in neutron stars is a major effort in astrophysics, having significant impact in several topics. A detailed evolutionary model requires, at the same time, the numerical solution of the heat diffusion equation, the use of appropriate numerical methods to control non-linear terms in the induction equation, and the local calculation of realistic microphysics coefficients. Here we present the latest extension of the magneto-thermal 2D code in which we have coupled the crustal evolution to the core evolution, including ambipolar diffusion. It has also gained in modularity, accuracy, and efficiency. We revise the most suitable numerical methods to accurately simulate magnetar-like magnetic fields, reproducing the Hall-driven magnetic discontinuities. From the point of view of computational performance, most of the load falls on the calculation of microphysics coefficients. To a lesser extent, the thermal evolution part is also computationally expensive because it requires large matrix inversions due to the use of an implicit method. We show two representative case studies: (i) a non-trivial multipolar configuration confined to the crust, displaying long-lived small-scale structures and discontinuities; and (ii) a preliminary study of ambipolar diffusion in normal matter. The latter acts on timescales that are too long to have relevant effects on the timescales of interest but sets the stage for future works where superfluid and superconductivity need to be included.

In this work we show that the area of the event horizon of the Chong–Cvetic–Lu–Pope black hole can be reconstructed in terms of the spectra of the Laplacian on the event horizon. This result, which extends previous works regarding the de Sitter–Kerr–Newman case, points towards a possible description of the black hole degrees of freedom in terms of the spectra of canonical operators defined on the event horizon.

When magnetic atoms are inserted inside a superconductor, the superconducting order is locally depleted as a result of the antagonistic nature of magnetism and superconductivity. Thereby, distinctive spectral features, known as Yu–Shiba–Rusinov states, appear inside the superconducting gap. The search for Yu–Shiba–Rusinov states in different materials is intense, as they can be used as building blocks to promote Majorana modes suitable for topological quantum computing. Here, the first observation of Yu–Shiba–Rusinov states in graphene, a non-superconducting 2D material, and without the participation of magnetic atoms, is reported. Superconductivity in graphene is induced by proximity effect brought by adsorbing nanometer-scale superconducting Pb islands. Using scanning tunneling microscopy and spectroscopy the superconducting proximity gap is measured in graphene, and Yu–Shiba–Rusinov states are visualized in graphene grain boundaries. The results reveal the very special nature of those Yu–Shiba–Rusinov states, which extends more than 20 nm away from the grain boundaries. These observations provide the long-sought experimental confirmation that graphene grain boundaries host local magnetic moments and constitute the first observation of Yu–Shiba–Rusinov states in a chemically pure system.

In this work, the role of a time-varying Newton constant under the scale-dependent approach is investigated in the thermodynamics of the Friedman equations. In particular, we show that the extended Friedman equations can be derived either from equilibrium thermodynamics when the non-matter energy momentum tensor is interpreted as a fluid or from non-equilibrium thermodynamics when an entropy production term, which depends on the time-varying Newton constant, is included. Finally, a comparison between black hole and cosmological thermodynamics in the framework of scale-dependent gravity is briefly discussed.

Context. In the central few degrees of the bulge of the Milky Way there is a flattened structure of gas, dust, and stars, known as the central molecular zone, that is similar to nuclear disks in other galaxies. As a result of extreme foreground extinction, we possess only sparse information about the (mostly old) stellar population of the nuclear disk. Aims. In this work we present our KMOS spectroscopic survey of the stars in the nuclear disk reaching the old populations. To obtain an unbiased data set, we sampled stars in the full extinction range along each line of sight. Methods. We also observed reference fields in neighboring regions of the Galactic bulge. We describe the design and execution of the survey and present first results. Results. We obtain spectra and five spectral indices of 3113 stars with a median S/N of 67 and measure radial velocities for 3051 stars. Of those, 2735 sources have sufficient S/N to estimate temperatures and metallicities from indices. Conclusions. We derive metallicities using the CO 2-0 and Na I K-band spectral features, where we derive our own empirical calibration using metallicities obtained with higher-resolution observations. We use 183 giant stars for calibration spanning in metallicity from −2.5 to 0.6 dex and covering temperatures of up to 5500 K. The derived index based metallicities deviate from the calibration values with a scatter of 0.32 dex. The internal uncertainty of our metallicities is likely smaller. We use these metallicity measurements, together with the CO index, to derive effective temperatures using literature relations. We publish the catalog in this paper. Our data set complements Galactic surveys such as Gaia and APOGEE for the inner 200 pc radius of the Milky Way, which is not readily accessible by those surveys owing to extinction. We will use the derived properties in future papers for further analysis of the nuclear disk.

Obscuration and confusion conspire to limit our knowledge of the inner Milky Way. Even at moderate distances, the identification of stellar systems becomes compounded by the extremely high density of background sources. Here we provide a very revealing example of these complications by unveiling a large, massive, young cluster in the Sagittarius arm that has escaped detection until now despite containing more than 30 stars brighter than G = 13. By combining Gaia DR2 astrometry, Gaia and 2MASS photometry and optical spectroscopy, we find that the new cluster, which we name Valparaiso 1, located at ∼2.3 kpc, is about 75 Ma old and includes a large complement of evolved stars, among which we highlight the 4 d classical Cepheid CM Sct and an M-type giant that probably represents the first detection of an AGB star in a Galactic young open cluster. Although strong differential reddening renders accurate parameter determination unfeasible with the current dataset, direct comparison to clusters of similar age suggests that Valparaiso 1 was born as one of the most massive clusters in the Solar Neighbourhood, with an initial mass close to 104 M⊙.

En 1915 Einstein enunció la teoría de la relatividad general, gracias a esta las nociones de espacio y tiempo dejan de ser consideradas como entes independientes y pasan a ser un único concepto: el espacio-tiempo. El objetivo de este trabajo es realizar un estudio, introductorio pero riguroso, a la estructura matemática del espacio-tiempo y enunciar los teoremas de singularidad de Penrose y Hawking, considerados como el gran avance de la teoría de la relatividad del siglo XX. La estructura de esta memoria será la siguiente: primero se darán una introducción histórica al concepto de espacio-tiempo, seguidamente se explicarán las herramientas matemáticas necesarias para comprender el espacio-tiempo. En la segunda sección se darán condiciones físicas sobre el espacio-tiempo necesarias para poder formular y dar una idea de cómo se demuestran los teoremas de singularidad que ocupan la tercera sección. Por último veremos las consecuencias que han tenido tales resultados.

El hecho de que la fenomenología de un superconductor se pueda explicar mediante un fotón masivo y que esto surja a partir de una ruptura espontánea de la simetría gauge U(1), inspiró el desarrollo del mecanismo de Higgs, por el cual las partículas adquieren masa. El objetivo de este trabajo es estudiar las analogías entre el modelo de Higgs y las teorías de superconductividad de Ginzburg-Landau (GL) y de Bardeen-Cooper-Schrieffer (BCS). Para ello, se introducen los conceptos de simetría gauge global y local, la mecánica lagrangiana y el formalismo de la segunda cuantización. Primero se presenta el modelo abeliano de Higgs U(1), para después desarrollar la teoría GL y buscar analogías. Lo mismo se hace con la teoría BCS. Estas teorías se basan en la ruptura de la simetría gauge local (Higgs, espontáneamente) o global (GL y BCS, dinámicamente), aunque más allá de eso, se concluye que son fundamentalmente analogías formales, sin un contenido físico común. Aun así, también se plantean las hipótesis que surgen al intentar igualar desde el punto de vista físico el modelo de Higgs y las teorías de superconductividad: una ruptura de simetría gauge local U(1) dinámica o un bosón de Higgs compuesto.

En el siguiente trabajo se estudia de forma teórica y práctica el problema abierto en la Astrofísica que corresponde a la falta de masa observada en el Universo y, en concreto, en las galaxias. Mediante una serie de simulaciones realizadas en Python, con los correspondientes códigos de análisis escritos en el mismo lenguaje, se realiza un estudio del papel de la Materia Oscura y la Dinámica Newtoniana Modificada (MOND) como soluciones al problema de la falta de masa en las galaxias y, en concreto, se intenta simular la Vía Láctea. El análisis se realiza sobre las curvas de velocidades, las distribuciones de velocidades, la morfología y la estabilidad de los discos simulados. El estudio teórico empieza por la dinámica de los sistemas sin colisiones que constituyen las galaxias, desarrollando la ecuación de Boltzmann, las ecuaciones de Jeans y el Teorema de Jeans, necesarios para el análisis teórico de tales sistemas. Posteriormente se desarrolla la materia oscura y se expone la distribución de masa de materia oscura que se va a usar en las simulaciones, el perfil de Navarro-Frenk-White (NFW). El último apartado de teoría corresponde a una breve introducción de MOND y, en concreto, de la ley de Milgrom, que es la que se va a implementar para analizar los efectos de MOND en la evolución galáctica. Una vez establecidas las bases teóricas, se realiza una descripción de los métodos numéricos empleados para poder realizar la simulación. Se introduce el algoritmo de Verlet como integrador temporal, y los métodos de suma directa y particle mesh como métodos para calcular la fuerza sobre cada una de las partículas de la simulación. La última parte de la metodología corresponde a la construcción de las condiciones iniciales del sistema que se va a simular. Se introducen los criterios de estabilidad de los discos autogravitantes desarrollados por Toomre y Ostriker-Peebels y se realiza un cálculo, bajo ciertas aproximaciones, de la distribución inicial de velocidades, dada la di

Nowadays, there exist many physical realizations of qubits for quantum computing. Some modern and prominent examples of types of quantum computer platforms are the superconducting qubits, spin qubits, trapped-ion qubits, photonic qubits and topological qubits. In this document, we overview the underlying physical principles of three of these platforms: superconducting qubits, spin qubits in semiconductors and trapped-ion qubits. This work is also meant to serve as an introduction to these technologies. This document is organized as follows. First, we introduce the so called DiVincenzo criteria [3] that de ne the requirements that a system has to meet to be useful as a quantum computer, with a brief explanation of the decoherence and the Bloch sphere. Second, we go through the three quantum computer platforms. The second part begins with an introduction to the superconducting qubits by explaining some basic concepts of superconductivity such as the Meissner effect and the flux quantization on a superconducting ring. This is done in order to understand the basics of the Josephson junctions used in this type of qubits. Then, the three main types of superconducting qubits are explained. Superconducting qubits can be divided on three main types depending on the variable chosen to encode the qubit state: charge qubits, phase qubits and flux qubits. In the sections dedicated to the charge qubits, the Cooper pair box, which is the predecessor to the transmon qubit, is explained in order to understand the transmon qubits. We focus our attention mainly on the transmon qubit because it seems to be the most popular type of superconducting qubit. In the following sections, the spin qubits and the trapped-ion qubits are also explained. There are also different possibilities for implementing spin qubits like, for example, in NV-centers in a diamond lattice, color centers, spins on molecules, shallow dopants or electrostatically confined quantum dots in semiconductors. We focus on

We explore the possibility of inferring the properties of the Galactic population of neutron stars through machine learning. In particular, in this paper we focus on their dynamical characteristics and show that an artificial neural network is able to estimate with high accuracy the parameters that control the current positions of a mock population of pulsars. For this purpose, we implement a simplified population-synthesis framework (where selection biases are neglected at this stage) and concentrate on the natal kick-velocity distribution and the distribution of birth distances from the Galactic plane. By varying these and evolving the pulsar trajectories in time, we generate a series of simulations that are used to train and validate a suitably structured convolutional neural network. We demonstrate that our network is able to recover the parameters governing the distribution of kick velocity and Galactic height with a mean relative error of about 10−2. We discuss the limitations of our idealized approach and study a toy problem to introduce selection effects in a phenomenological way by incorporating the observed proper motions of 216 isolated pulsars. Our analysis highlights that by increasing the sample of pulsars with accurate proper-motion measurements by a factor of ∼10, one of the future breakthroughs of the Square Kilometre Array, we might succeed in constraining the birth spatial and kick-velocity distribution of the neutron stars in the Milky Way with high precision through machine learning.

We study spin excitations and the Kondo effect in open-shell nanographenes, motivated by recent scanning tunneling inelastic spectroscopy experiments. Specifically, we consider three systems: the triangulene, the extended triangulene with rocket shape, both with an S = 1 ground state, and a triangulene dimer with S = 0 on account of intermolecular exchange. We focus on the consequences of hybridization of the nanographene zero modes with a conducting substrate on the dI/dV line shapes associated with spin excitations. The partially filled nanographene zero modes coupled to the conduction electrons in the substrate constitute multiorbital Anderson impurity models that we solve in the one-crossing approximation, which treats the coupling to the substrate to infinite order. We find that the coupling to the substrate leads to (i) renormalization of the spin flip excitation energies of the bare molecule, (ii) broadening of the spectral features, and (iii) the emergence of zero bias Kondo peaks for the S = 1 ground states. The calculated substrate induced shift of the spin excitation energies is found to be significantly larger than their broadening, which implies that this effect has to be considered when comparing experimental results and theory.

Context. Observations of massive stars in open clusters younger than ∼8 Myr have shown that a majority of them are in binary systems, most of which will interact during their life. While these can be used as a proxy of the initial multiplicity properties, studying populations of massive stars older than ∼20 Myr allows us to probe the outcome of these interactions after a significant number of systems have experienced mass and angular momentum transfer and may even have merged. Aims. Using multi-epoch integral-field spectroscopy, we aim to investigate the multiplicity properties of the massive-star population in the dense core of the ∼40 Myr old cluster NGC 330 in the Small Magellanic Cloud in order to search for possible imprints of stellar evolution on the multiplicity properties. Methods. We obtained six epochs of VLT/MUSE observations operated in wide-field mode with the extended wavelength setup and supported by adaptive optics. We extracted spectra and measured radial velocities for stars brighter than mF814W = 19. We identified single-lined spectroscopic binaries through significant RV variability with a peak-to-peak amplitude larger than 20 km s−1. We also identified double-lined spectroscopic binaries, and quantified the observational biases for binary detection. In particular, we took into account that binary systems with similar line strengths are difficult to detect in our data set. Results. The observed spectroscopic binary fraction among stars brighter than mF814W = 19 (approximately 5.5 M⊙ on the main sequence) is fSBobs = 13.2 ± 2.0%. Considering period and mass ratio ranges from log(P) = 0.15−3.5 (about 1.4 to 3160 d), q = 0.1−1.0, and a representative set of orbital parameter distributions, we find a bias-corrected close binary fraction of fcl = 34−7+8%. This fraction seems to decline for the fainter stars, which indicates either that the close binary fraction drops in the B-type domain, or that the period distribution becomes more heavily weighted

Prediction of material performance in fusion reactor environments relies on computational modelling, and will continue to do so until the first generation of fusion power plants come on line and allow long-term behaviour to be observed. In the meantime, the modelling is supported by experiments that attempt to replicate some aspects of the eventual operational conditions. In 2019, a group of leading experts met under the umbrella of the IEA to discuss the current position and ongoing challenges in modelling of fusion materials and how advanced experimental characterisation is aiding model improvement. This review draws from the discussions held during that workshop. Topics covering modelling of irradiation-induced defect production and fundamental properties, gas behaviour, clustering and segregation, defect evolution and interactions are discussed, as well as new and novel multiscale simulation approaches, and the latest efforts to link modelling to experiments through advanced observation and characterisation techniques.

In this work, motivated by the fact that higher dimensional theories predict the existence of black holes which differ from their four dimensional counterpart, we analyse the geodesics and black hole shadow cast by a general non-extremal five dimensional black hole. The system under consideration corresponds to the Chong–Cvetič–Lü–Pope (Chong et al., 2005), which has the Myers–Perry black hole as a limit.

We study the electronic properties of the heterobilayer of vanadium and iron oxychlorides, VOCl and FeOCl, two layered air stable van der Waals insulating oxides with different types of antiferromagnetic order in bulk: VOCl monolayers are ferromagnetic (FM) whereas the FeOCl monolayers are antiferromagnetic (AF). We use density functional theory calculations, with Hubbard correction that is found to be needed to describe correctly the insulating nature of these compounds. We compute the magnetic anisotropy and propose a spin model Hamiltonian. Our calculations show that interlayer coupling is weak and hence the magnetic order of each monolayers is preserved in the heterobilayer. Thus, the heterobilayer combines antiferromagnetic and ferromagnetic orders. Interlayer exchange should lead both to exchange bias and to the emergence of hybrid collective modes that combine FM and AF magnons. The energy band of the heterobilayer show a type II band alignment, and feature spin-splitting of the states of the AF layer due to the breaking of the inversion symmetry.

Nanomaterials made of cerium oxides CeO2 and Ce2O3 have a broad range of applications, from catalysts in automotive, industrial or energy operations to promising materials to enhance hadrontherapy effectiveness in oncological treatments. To elucidate the physico-chemical mechanisms involved in these processes, it is of paramount importance to know the electronic excitation spectra of these oxides, which are obtained here through high-accuracy linear-response time-dependent density functional theory calculations. In particular, the macroscopic dielectric response functions [small epsilon, Greek, macron] of both bulk CeO2 and Ce2O3 are derived, which compare remarkably well with the available experimental data. These results stress the importance of appropriately accounting for local field effects to model the dielectric function of metal oxides. Furthermore, we reckon the energy loss functions Im(−1/[small epsilon, Greek, macron]) of the materials, including the accurate evaluation of the momentum transfer dispersion from first-principles calculations. In this respect, by using Mermin-type parametrization we are able to model the contribution of different electronic excitations to the dielectric loss function. Finally, from the knowledge of the electron inelastic mean free path, together with the elastic mean free path provided by the relativistic Mott theory, we carry out statistical Monte Carlo (MC) electron transport simulations to reproduce the major features of the reported experimental reflection electron energy loss (REEL) spectra of cerium oxides. The good agreement with REEL experimental data strongly supports our approach based on MC modelling, whose main inputs were obtained using ab initio calculated electronic excitation spectra in a broad range of momentum and energy transfers.

High-transparency polymers, called optical polymers (OPs), are used in many thin-film devices, for which the knowledge of film thickness (h) and refractive index (n) is generally required. Spectrophotometry is a cost-effective, simple and fast non-destructive method often used to determine these parameters simultaneously, but its application is limited to films where h > 500 nm. Here, a simple spectrophotometric method is reported to obtain simultaneously the n and h of a sub-micron OP film (down to values of a few tenths of a nm) from its transmission spectrum. The method is valid for any OP where the n dispersion curve follows a two-coefficient Cauchy function and complies with a certain equation involving n at two different wavelengths. Remarkably, such an equation is determined through the analysis of n data for a wide set of commercial OPs, and its general validity is demonstrated. Films of various OPs (pristine or doped with fluorescent compounds), typically used in applications such as thin-film organic lasers, are prepared, and n and h are simultaneously determined with the proposed procedure. The success of the method is confirmed with variable-angle spectroscopic ellipsometry.

In this work we show several singularity theorems which can be applied to the Reissner-Nordström spacetime. To date, only two results [Phys. Rev. D 50, 3692 (1994); Lett. Math. Phys. 110, 2383 (2020)] have predicted null incompleteness in this case. In addition, we show that regular black holes in the Bardeen category have noncompact slices without the standard assumption regarding the knowledge of regions at infinity and, therefore, that they exhibit topology changes.