Pulsed light beams in vacuum with superluminal and negative group velocities

Gouy's phase of transversally limited pulses can create a strong anomalous dispersion in vacuum leading to highly superluminal and negative group velocities. As a consequence, a focusing pulse can diverge beyond the focus before converging into it. A simple experiment is proposed.Comment: 4 pages, 5 figure

Color Superconducting Phases of Cold Dense Quark Matter

We investigate color superconducting phases of cold quark matter at densities relevant for the interiors of compact stars. At these densities, electrically neutral and weak-equilibrated quark matter can have unequal numbers of up, down, and strange quarks. The QCD interaction favors Cooper pairs that are antisymmetric in color and in flavor, and a crystalline color superconducting phase can occur which accommodates pairing between flavors with unequal number densities. In the crystalline color superconductor, quarks of different flavor form Cooper pairs with nonzero total momentum, yielding a condensate that varies in space like a sum of plane waves. Rotational and translational symmetry are spontaneously broken. We use a Ginzburg-Landau method to evaluate candidate crystal structures and predict that the favored structure is face-centered-cubic. We predict a robust crystalline phase with gaps comparable in magnitude to those of the color-flavor-locked phase that occurs when the flavor number densities are equal. Crystalline color superconductivity will be a generic feature of the QCD phase diagram, occurring wherever quark matter that is not color-flavor locked is to be found. If a very large flavor asymmetry forbids even the crystalline state, single-flavor pairing will occur; we investigate this and other spin-one color superconductors in a survey of generic color, flavor, and spin pairing channels. Our predictions for the crystalline phase may be tested in an ultracold gas of fermionic atoms, where a similar crystalline superfluid state can occur. If a layer of crystalline quark matter occurs inside of a compact star, it could pin rotational vortices, leading to observable pulsar glitches.Comment: Ph.D. thesis, submitted to the MIT Department of Physics, May 2003. Five chapters and two appendices (180 pages, 30 figures). Chapters 1 and 5 are new: chapter 1 is a detailed review of previous work, and chapter 5 discusses applications of the crystalline phase for the physics of pulsar spin glitches and cold trapped atom

The influence of digital capabilities on customer orientation of service employees (COSE) and its consequences on customer satisfaction and e-WOM within Family Businesses

Customer relations have become a key matter in services businesses daily activities. Due to the intangibility of services, the employee service performance is what customers perceive as the reflection of the service quality. Due to this fact, the customer orientation of front-line employees, primarily in services industry, plays a crucial role in getting positives/negatives results with regards to customer satisfaction. Customer orientation of service employees (COSE) is a key concept within marketing literature. It has been demonstrated by previous authors the positives effects that has in customer satisfaction and customer retention (Hennig-Thurau. 2004: Morales and Ruiz-Alba, 2018)

International Management of Customer Orientation

This study investigates the role of customer orientation of service employees (COSE) and its influence on customer satisfaction and on electronic word of mouth (e-WOM), with a focus on international management. An empirical study was conducted amongst hotel customers with a final valid sample of 265 respondents. Digital capabilities have been included in the COSE model for the first time. Findings indicate that digital capabilities have a positive influence on customer satisfaction that is mediated by COSE. This study has also compared differences between international and national firms and also considered family businesses and non-family businesses. Results show that international hotels have a higher level of COSE than national hotels, mainly due to the technical skills of the employees, and the presence of a higher level of COSE in family businesses (FBs) rather than in non-family businesses (NFBs). Some contributions to academia and to international management have been discussed

Association of oral lichen planus with hepatic disorders and hepatocellular carcinoma:systematic review and meta-analysis

Oral lichen planus (OLP) is a prevalent autoimmune chronic inflammatory disease of unknown etiology. The importance of the association between hepatic disease and OLP lies in the fact that many of these disorders (HC, HB, cirrhosis, hepatic steatosis) behave as risk factors for hepatocellular carcinoma. We searched PubMed, Embase, Web of Science, and Scopus for studies published before January 2022. We evaluated the quality of studies (Joanna Briggs Institute tool). We performed meta-analyses, investigated the heterogeneity between studies, and we also carried out subgroups, meta-regression, and small-study effects analyses. 146 studies (21,187 patients) were included in this study. Our study aims to evaluate current evidence on the prevalence and magnitude of association between hepatic diseases (especially those with risk of malignancy), hepatocellular carcinoma and OLP. Our results suggest that patients with OLP present a significant tendency to the development of hepatitis B (OR=1.62, 95%CI=1.01-2.40, p=0.02), hepatitis C (OR=4.09, 95%CI=2.77-6.03, p<0.001), cirrhosis (OR=5.58, 95%CI=1.83-16.96, p=0.002), hepatic steatosis (OR=5.71, 95%CI=0.97-33.60, p=0.05) and hepatocellular carcinoma (OR=3.10,95%CI=1.14-8.43, p=0.03). Patients with OLP should be investigated to rule out the presence of hepatic disease, which can lead to hepatocellular carcinoma, allowing an early diagnosis that would help to a better approach to liver disease and a noTable improvement in prognosis in terms of both progression and severity

Few cycle pulse propagation

We present a comprehensive framework for treating the nonlinear interaction of few-cycle pulses using an envelope description that goes beyond the traditional SVEA method. This is applied to a range of simulations that demonstrate how the effect of a $\chi^{(2)}$ nonlinearity differs between the many-cycle and few-cycle cases. Our approach, which includes diffraction, dispersion, multiple fields, and a wide range of nonlinearities, builds upon the work of Brabec and Krausz[1] and Porras[2]. No approximations are made until the final stage when a particular problem is considered. The original version (v1) of this arXiv paper is close to the published Phys.Rev.A. version, and much smaller in size.Comment: 9 pages, 14 figure

Analytical study of Roman glasses from Southeastern Spain

Recent archaeological excavations carried out in the Iberian-Roman city of La Alcudia (Ilici , Hispania) have provided some important assemblages of Roman glass. The present paper summarizes the results of archaeological and archaeometric studies carried out on two assemblages from different sectors and chronology. The first set of glasses was unearthed in a sector corresponding to a section of the city’s west wall. The level in which the glasses were found is dated from the mid 1st to the mid 2nd century AD. The second set of glasses comes from an area known as Casitas Ibéricas (4th - 7th centuries AD). These glasses were found in ditches and pits, which had disturbed the more ancient archaeological levels. Most of the fragments in both sets represent blown glass. The archaeometric study concentrated on deter-mining the chemical composition of a representative selection of glass fragments from the two chronological periods in order to observe possible differences between them. Chromophores responsible for glass colour were identified. Moreover, the state of conservation of the glasses was evaluated in order to determine the nature of degradation processes. The samples were studied using conventional optical microscopy (OM), X-ray fluorescence spectrometry (XRF), field emission scanning electron microscopy (FESEM), energy dispersive X-ray microanalysis (EDX), and visible spectrophotometry (VIS)

Quality of education and university workspaces

La sociedad actual avanza a pasos agigantados, circunstancia que exige de nuestro modelo educativo un cambio paralelo a dichos avances. La educación es uno de los motores de cambio y como tal debe dar respuesta a las exigencias que se le planteen. Es mucha la bibliografía que podemos encontrar acerca de la calidad educativa, pero muy poca de ésta se centra en la evaluación de la calidad de los espacios educativos como tales. Desde este estudio se pretende analizar los puntos de vista y exigencias de los estudiantes de la Facultad de Ciencias de la Educación de la Universidad de Granada respecto a dichos espacios educativos.Today's society is moving forward at a rapid pace, a fact that requires that our educational model change in parallel with such developments. Education is one of the drivers of change and as such must respond to the demands made on it. There is ample literature about the quality of education, but very little of it focuses on assessing the quality of educational spaces as such. The aim of this study is to examine the views and needs of students at the Faculty of Education at the University of Granada with respect to such educational spaces.Departamento de Psicología Socia

Experimental data on SOA formation from mixtures of anthropogenic and biogenic organic compounds

AbstractSecondary organic aerosols (SOA) constitute a significant fraction of the atmospheric particulate matter. Theses particles are formed as a consequence of the oxidation reaction of certain organic gases that leads to the formation of low-volatility compounds. As for other pollutants, air quality models allow the simulation of particle levels and thus models constitute a powerful tool in air quality management. Nevertheless, the accepted use of models must be based on the validation of its capacity to reproduce observed concentrations. Air monitoring sites provide measured information of a large variety of ambient pollutants. Unfortunately, measurements on SOA are not normally available, as current monitoring networks do not include instrumentation to distinguish primary from secondary sources of organic carbonaceous aerosol. This paper presents a set of photooxidation experiments performed in the European Photorreactor (EUPHORE) smog chamber (CEAM, Spain) under different experimental conditions to investigate SOA formation. The use of chambers allows the isolation of atmospheric chemistry and aerosol formation processes. Thus, although these measurements were obtained at initial precursor concentrations higher than those in atmospheric conditions, they constitute a valuable set of information for SOA model evaluation purposes