Analytical determination of coronal parameters using the period ratio P₁/2P₂

<p>Context. In transverse coronal loop oscillations, two periodicities have been measured simultaneously and are interpreted as the fundamental kink mode (with period P1) and the first harmonic (with period P2). Deviations of the period ratio P1/2P2 from unity provide information about the extent of longitudinal structuring within the loop.</p> <p>Aims. Here we develop an analytical approximation that describes the shift in P1/2P2 in terms of the ratio L/Λc of the length 2L of a coronal loop and the density scale height Λc.</p> <p>Methods. We study the MHD wave equations in a low β plasma using the thin tube approximation. Disturbances are described by a differential equation which may be solved for various equilibrium density profiles, obtaining dispersion relations in terms of Bessel functions. These dispersion relations may be used to obtain analytical approximations to the periods P1 and P2. We also present a variational approach to determining the period ratio and show how the WKB method may be used.</p> <p>Results. Analytical approximations to the period ratio P1/2P2 are used to shed light on the magnitude of longitudinal structuring in a loop, leading to a determination of the density scale height. We apply our formula to the observations in Verwichte et al. (2004) and Van Doorsselaere et al. (2007), obtaining the coronal density scale height.</p> <p>Conclusions. Our simple formula and approximate approaches highlight a useful analytical tool for coronal seismology. We demonstrate that P1/2P2 is linked to the density scale height, with no need for estimates of other external parameters. Given the accuracy of current observations, our formula provides a convenient means of determining density scale heights.</p&gt

Consensos sobre la naturaleza de la ciencia: fundamentos de una investigación empírica

Las cuestiones relativas a la naturaleza de la ciencia constituyen hoy uno de los elementos esenciales de la alfabetización científica y tecnológica para todas las personas. Sin embargo, la inclusión de la naturaleza de la ciencia en el currículo de ciencias no es fácil y requiere, entre otras cosas, el establecimiento previo de acuerdos sobre sus principales características y los contenidos que podrían trasladarse al aula para su tratamiento explícito en la educación científica. En este artículo se revisan algunas aportaciones de la didáctica de las ciencias a estas importantes cuestiones. Así mismo, se describe una metodología empírica destinada a conseguir un consenso sobre la naturaleza de la ciencia, entendida ésta en un sentido amplio; acuerdos que se extienden tanto a los aspectos que se consideran adecuados como a lo que se estiman inadecuados.Palabras clave: Naturaleza de la ciencia, disenso, consenso, currículo de ciencias, Cuestionario de Opiniones CTS, metodología empírica.Consensus on the nature of science: the basis of empirical researchThe issues about the nature of science are today considered a core content of the scientific and technological literacy for all. However, the inclusion of the nature of science in the science school curriculum is not easy and requires some conditions. One important condition is setting up previous agreements on the specific features and contents of the nature of science that could be translated into the classroom practice for its explicit use in school science education. This paper reviews some contributions of the science education research to achieve this condition. Finally, an empiric methodology designed to achieve consensus on the nature of science is put forward; the description embraces the agreements on the appropriate as well as on the inappropriate features of the nature of science.Keywords: Nature of the science, disagreement, consensus, science school curriculum, Questionnaire of Opinions on STS, empiric methodology

Evaluación de los efectos de la materia CTS de bachillerato en las actitudes CTS del alumnado con una metodología de respuesta múltiple

En este estudio se presenta la aplicación del Cuestionario de Opiniones de Ciencia, Tecnología y Sociedad (COCTS) con una nueva metodología de respuesta múltiple para la evaluación más válida y significativa de las actitudes relacionadas con los temas Ciencia, Tecnología y Sociedad (CTS) de una muestra de estudiantes, así como la eficacia de un curso correspondiente a la asignatura “Ciencia, Tecnología y Sociedad” de bachillerato para modificar las creencias y actitudes iniciales del alumnado. Se analiza esta metodología, su validez para el contraste estadístico de hipótesis y su capacidad para evaluar de manera más precisa, cualitativa y cuantitativamente, las creencias y actitudes CTS del alumnado con el objeto de dar cuenta de los cambios que se producen después de su participación en el curso CTS.Palabras Clave: Evaluación de actitudes CTS; Cuestionario de Opiniones CTS; Modelo de Respuesta Múltiple; Evaluación de la asignatura “Ciencia, Tecnología y Sociedad”.Evaluation of the effects of the CTS subject of high school in the CTS attitudes of students with a multiple response methodologyThis study applies the Views on Science, Technology, and Society Questionnaire (Spanish acronym COCTS) through a new methodology of multiple answer to achieve valid and significant evaluation of the attitudes related to Science, Technology and Society (STS) topics. The study is aimed to measure the effects of the Science, Technology and Society High-school subject on the pupils’ initial beliefs and attitudes. The results analyze the applied methodology, its validity for the statistical hypothesis testing on the subject’s significant effects, as well as its capacity to qualitatively and quantitatively evaluate the changes of the pupil’s STS attitudes through their participation in the STS subject.Key Words: STS Attitude Evaluation; Views on STS Questionnaire; Multiple Answer Model; “Science, Technology and Society” Curriculum Evaluation

Consensos sobre la naturaleza de la ciencia: aspectos epistemológicos

La inclusión de la naturaleza de la ciencia en el currículo de ciencias requiere, como requisito previo, el establecimiento de acuerdos sobre sus principales rasgos y los correspondientes contenidos que podrían trasladarse al aula para su tratamiento explícito en la educación científica. En este artículo se muestran los consensos conseguidos en una investigación empírica sobre cuestiones de NdC correspondientes a la epistemología de la ciencia y a las definiciones de ciencia y tecnología y las relaciones entre ambas. Se ha seguido para ello una metodología basada en la valoración de las cuestiones incluidas en el Cuestionario de Opiniones sobre Ciencia, Tecnología y Sociedad (COCTS) por parte de un panel de 16 jueces expertos. Los acuerdos alcanzados se extienden tanto a los aspectos de NdC que se consideran adecuados como a los inadecuados, los cuales son mucho más numerosos.Palabras clave: Naturaleza de la ciencia, aspectos epistemológicos, consenso, Cuestionario de Opiniones CTS, investigación empírica.Consensus on the nature of science: epistemological aspectsA previous condition to effectively insert the nature of science in the science school curriculum requires setting up the agreements on the main features of the curriculum contents that should be explicitly addressed into the science classroom. This paper shows some agreements that have been attained through an empiric methodology of research, which is based on the assessment of the questions included in the Questionnaire of Opinions on Science, Technology and Society (COCTS) by a panel of 16 expert judges. The reached consensuses are limited here to the specific issues of the epistemology of the science, which not only include issues of philosophy of science but also the definitions of science and technology and their relationships. The results display both some appropriate traits as well as those more numerous inadequate traits revealed by the empirical analysis that has been carried out.Key Words: Nature of science, epistemological traits, consensus, Questionnaire of Opinions on STS, empiric investigation

The evolution of H{\sc ii} galaxies: Testing the bursting scenario through the use of self-consistent models

We have computed a series of realistic and self-consistent models of the emitted spectra of H{\sc ii} galaxies. Our models combine different codes of chemical evolution, evolutionary population synthesis and photoionization. The emitted spectrum of H{\sc ii} galaxies is reproduced by means of the photoionization code CLOUDY, using as ionizing spectrum the spectral energy distribution of the modelled H{\sc ii} galaxy, which in turn is calculated according to a Star Formation History (SFH) and a metallicity evolution given by a chemical evolution model that follows the abundances of 15 different elements. The contribution of emission lines to the broad-band colours is explicitly taken into account. The results of our code are compared with photometric and spectroscopic data of H{\sc ii} galaxies. Our technique reproduces observed diagnostic diagrams, abundances, equivalent width-colour and equivalent width-metallicity relations for local H{\sc ii} galaxies.Comment: 13 figures and 2 tables, accepted for publication in MNRAS Main Journa

Opinion dynamics: models, extensions and external effects

Recently, social phenomena have received a lot of attention not only from social scientists, but also from physicists, mathematicians and computer scientists, in the emerging interdisciplinary field of complex system science. Opinion dynamics is one of the processes studied, since opinions are the drivers of human behaviour, and play a crucial role in many global challenges that our complex world and societies are facing: global financial crises, global pandemics, growth of cities, urbanisation and migration patterns, and last but not least important, climate change and environmental sustainability and protection. Opinion formation is a complex process affected by the interplay of different elements, including the individual predisposition, the influence of positive and negative peer interaction (social networks playing a crucial role in this respect), the information each individual is exposed to, and many others. Several models inspired from those in use in physics have been developed to encompass many of these elements, and to allow for the identification of the mechanisms involved in the opinion formation process and the understanding of their role, with the practical aim of simulating opinion formation and spreading under various conditions. These modelling schemes range from binary simple models such as the voter model, to multi-dimensional continuous approaches. Here, we provide a review of recent methods, focusing on models employing both peer interaction and external information, and emphasising the role that less studied mechanisms, such as disagreement, has in driving the opinion dynamics. [...]Comment: 42 pages, 6 figure

Neutral Bremsstrahlung Emission in Xenon Unveiled

[EN] We present evidence of non-excimer-based secondary scintillation in gaseous xenon, obtained using both the NEXT-White time projection chamber (TPC) and a dedicated setup. Detailed comparison with first-principle calculations allows us to assign this scintillation mechanism to neutral bremsstrahlung (NBrS), a process that is postulated to exist in xenon that has been largely overlooked.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under Advanced Grant No. 339787-NEXT; the European Unions Framework Program for Research and Innovation Horizon 2020 (20142020) under Grant Agreements No. 674896, No. 690575, and No. 740055; the Ministerio de Economa y Competitividad and the Ministerio de Ciencia, Innovacin y Universidades of Spain under Grants No. FIS2014-53371-C04 and No. RTI2018-095979, the Severo Ochoa Program Grants No. SEV-2014-0398 and No. CEX2018-000867-S, and the Mara de Maeztu Program MDM-2016-0692; the Generalitat Valenciana under Grants No. PROMETEO/2016/120 and No. SEJI/2017/011; the Portuguese FCT under Project No. PTDC/FIS-NUC/3933/2021 and under Project No. UIDP/04559/2020 to fund the activities of LIBPhys-UC; the U.S. Department of Energy under Contracts No. DE-AC02-06CH11357 (Argonne National Laboratory), No. DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), No. DE-FG02-13ER42020 (Texas A&M), and No. DE-SC0019223/DE-SC0019054 (University of Texas at Arlington); and the University of Texas at Arlington (USA). D. G.-D. acknowledges Ramon y Cajal program (Spain) under Contract No. RYC- 2015-18820. J. M.-A. acknowledges support from Fundacin Bancaria la Caixa (ID 100010434), Grant No. LCF/BQ/PI19/11690012. We would like to thank Lorenzo Muniz for insightful discussions on the subtleties of electron transport in gases.Henriques, C.; Amedo, P.; Teixeira, JMR.; González-Díaz, D.; Azevedo, C.; Para, A.; Martín-Albo, J.... (2022). Neutral Bremsstrahlung Emission in Xenon Unveiled. Physical Review X. 12(2):021005-1-021028-23. https://doi.org/10.1103/PhysRevX.12.021005021005-1021028-2312

Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\eta| < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286

A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE

In this small note we are concerned with the solution of Forward-Backward Stochastic Differential Equations (FBSDE) with drivers that grow quadratically in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem is a comparison result that allows comparing componentwise the signs of the control processes of two different qgFBSDE. As a byproduct one obtains conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio