cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
CMB power spectra and cosmological parameters from Planck PR4 with CamSpec
Creators: name: Rosenberg, Erik
name: Gratton, Steven
name: Efstathiou, George
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present angular power spectra and cosmological parameter constraints derived from the Planck PR4 (NPIPE) maps of the Cosmic Microwave Background. NPIPE, released by the Planck Collaboration in 2020, is a new processing pipeline for producing calibrated frequency maps from Planck data. We have created new versions of the CamSpec likelihood using these maps and applied them to constrain LCDM and single-parameter extensions. We find excellent consistency between NPIPE and the Planck 2018 maps at the parameter level, showing that the Planck cosmology is robust to substantial changes in the mapmaking. The lower noise of NPIPE leads to ~10% tighter constraints, and we see both smaller error bars and a shift toward the LCDM values for beyond-LCDM parameters including Omega_K and A_Lens.
description: 17 pages, 20 figures, updated to match accepted version
Quantifying Disorder One Atom at a Time Using an Interpretable Graph Neural Network Paradigm
Creators: name: Chapman, James
name: Hsu, Tim
name: Chen, Xiao
name: Heo, Tae Wook
name: Wood, Brandon C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Quantifying the level of atomic disorder within materials is critical to understanding how evolving local structural environments dictate performance and durability. Here, we leverage graph neural networks to define a physically interpretable metric for local disorder. This metric encodes the diversity of the local atomic configurations as a continuous spectrum between the solid and liquid phases, quantified against a distribution of thermal perturbations. We apply this novel methodology to three prototypical examples with varying levels of disorder: (1) solid-liquid interfaces, (2) polycrystalline microstructures, and (3) grain boundaries. Using elemental aluminum as a case study, we show how our paradigm can track the spatio-temporal evolution of interfaces, incorporating a mathematically defined description of the spatial boundary between order and disorder. We further show how to extract physics-preserved gradients from our continuous disorder fields, which may be used to understand and predict materials performance and failure. Overall, our framework provides an intuitive and generalizable pathway to quantify the relationship between complex local atomic structure and coarse-grained materials phenomena.
The ‘inward-looking’ securitization of the EU external migration policy in the New Pact on Migration and Asylum: a critical appraisal from a perspective of international law with reference to migration from Africa
Creators: name: Salvati, Pierluigi
Publisher: name: Universita' degli Studi di Salerno
Year: 2021
Subjects: External migration policy
Securitization
Externalization
Human security
Human development

description: The New Pact on Migration and Asylum presented by the European Commission in September 2020 largely outlines migration as a security threat both under an internal perspective and – although more latently – in the development of the external migration policy. In fact, it puts an emphasis on conflict prevention and resolution, as well as peace, security and governance strategies to be implemented in migrants’ countries of origin through ‘hard security’ policies aimed at de facto externalizing migration controls which resulted to be more instrumental in interdicting migratory flows than in eradicating their root causes. Such ‘securitarian’ approach does not seem to take full account of the broader consolidated contemporary dimension of the concept of security, which encompasses the protection of ‘human security’ which complements state security, strengthens human development and enhances human rights. The need to implement more human-security oriented strategies in order to manage the migration phenomenon more effectively seems to emerge clearly in relation to migration flows from the African continent.
La empresa y el modelo de negocio como agentes centrales para el desarrollo sustentable /
Creators: name: Hurtado Duéñez, Jesús Alonso
Publisher: name: Universidad Autónoma de Baja California, Mexicali.
Year: 2023
Subjects: subject: Desarrollo sostenible||Aspectos sociales||Tesis y disertaciones académicas||lemb||Desarrollo sostenible||Aspectos económicos||Tesis y disertaciones académicas||lemb
subject: HC79.H86 H87 2023

description: El origen y desarrollo de la presente investigación tienen su fundamento en consideraciones como la que establece Remacha (2017), con relación a la afirmación de que las actividades empresariales, han sido coparticipes de las problemáticas sociales, ambientales y económicas generadas, por lo cual se les ha emplazado a participar activamente en el desarrollo sustentable de su región de influencia. Con base en el requerimiento descrito, la investigación se estructuro con dos componentes, en primera instancia se desarrolló un modelo de negocio sustentable, considerando como referencia los conceptos de empresa como sistema, modelo de negocio y sustentabilidad en la empresa, el cual se estructura con base en las dimensiones social, ambiental y económica de la sustentabilidad. El diseño del modelo de negocios sustentable fue la referencia fundamental para el segundo componente de la investigación, que implico analizar el efecto que tienen las empresas pymes de bienes y servicios a la sustentabilidad de Mexicali. Tomando como base el modelo de negocios sustentable, se diseño una encuesta para evaluar a las empresas con relación a su desempeño con respecto a la sustentabilidad. Con la finalidad de determinar en qué nivel se encuentra cada empresa analizada con respecto a la sustentabilidad, se diseñó un indicador de sustentabilidad, el cual está compuesto por los índices económico, social y ambiental. Con el indicador de sustentabilidad planteado, se define en qué nivel se encuentra la empresa analizada, esto es, si es una empresa con deficiente accionar sustentable, en transición a la
Hydrodynamic spin-orbit coupling in asynchronous optically driven micro-rotors
Creators: name: Zion, Matan Yah Ben
name: Modin, Alvin
name: Chaikin, Paul M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Vortical flows of rotating particles describe interactions ranging from molecular machines to atmospheric dynamics. Yet to date, direct observation of the hydrodynamic coupling between artificial micro-rotors has been restricted by the details of the chosen drive, either through synchronization (using external magnetic fields) or confinement (using optical tweezers). Here we present a new active system that illuminates the interplay of rotation and translation in free rotors. We developed a non-tweezing circularly polarized beam that simultaneously rotates hundreds of silica-coated birefringent colloids. The particles rotate asynchronously in the optical torque field while freely diffusing in the plane. We observe that neighboring particles orbit each other with an angular velocity that depends on their spins. We derive an analytical model in the Stokes limit for pairs of spheres that quantitatively explains the observed dynamics. We then find that the geometrical nature of the low Reynolds fluid results in a universal hydrodynamic spin-orbit coupling. Our findings are of significance for the understanding and development of far-from-equilibrium materials.
Synthesis of optimal temperature regulator of electroarc holding furnace bath
Creators: name: Demin, Dmitriy
Publisher: name: figshare
Year: 2020
Subjects: subject: 99902 Engineering Instrumentation
subject: FOS: Other engineering and technologies

description: Purpose. To choose a procedure of synthesis of optimal regulator of melting temperature in electroarc holding furnace, obtain mathematical description that will provide the solution of regulator synthesis problem, and design the melting temperature evaluation methods to use during the process before the melt handling over on the casting conveyor. Methodology. To solve the problem of optimal control we have chosen the principle of Pontryagin’s maximum. To evaluate the parameters describing the control object, the procedure of regression equation obtaining was used. Findings. The article defines the problems to solve for synthesis of optimal temperature regulator of the electroarc furnace bath, working along with casting conveyor. The problems include the lack of mathematical description of the control object and the complexity of immediate estimation of the parameters describing the process. The procedure of estimation of the bath temperature based on the plotting of the regression equation has been suggested. It takes place during the temporary thermic process of melt treatment in a holding furnace. It describes the temperature profile of the bath and allows to surmount the main complexity of the synthesis of optimal regulator associated with the inability to measure the parameters describing the control object. Originality. The suggested pattern of mathematical description of the control object allows solving the problem of synthesis of optimal temperature regulator when the parameters describing the process are not subject to direct measurement. The use of the obtained optimal regulator allows getting optimal transients in the control object. Practical value. The application of the suggested regulator in industrial electroarc furnaces, operating as an electric shaker on the melting-priming area of a workshop, provides the possibility of bringing the melt chemical composition to the designated in the shortest time with minimal power expenses. This results in the reduction of possible downtime of casting conveyor caused by the absence of the melt of the proper quality, and the reduction of power expenses at the stage of thermothemporal processing of the melt.
title: 3 minutes pour développer son intelligence émotionnelle
title: journal filmé avec une classe d'enfants porteurs d'un handicap physique
titleType: Subtitle
Creators: name: Kozma, Kim
Publisher: name: Unknown
Year: 0
Subjects: subject: Intelligence émotionnelle
subject: Empathie
subject: Ecoute
subject: Apprentissages sociaux
subject: Plaisir
subject: Partage

description: Comment faire entrer le bonheur, le bien-être et le plaisir d’être ensemble dans ma classe d’enseignement spécialisé avec des enfants porteurs d’un handicap physique ? A la recherche d’une approche différente qui valorise l’humain plutôt que ses performances, je me suis intéressée à une autre forme d’intelligence. Le bonheur est aujourd’hui un sujet qui fascine le grand public et les scientifiques. Que de méthodes pour trouver son équilibre ! Une seule constance : cet équilibre passe par l’acquisition de compétence dans le domaine du « savoir être ». Comment développer ces compétences à l’école, comment les enseigner ? La classe est un lieu chargé d’affects et de relations. Les émotions y sont omniprésentes, elles interviennent dans nos facultés cognitives et relationnelles et participent à la satisfaction de nos besoins sociaux et d’appartenance. Améliorer son intelligence émotionnelle est un défi qui, aujourd’hui, semble être la priorité pour beaucoup, autant dans le monde du travail que dans celui de la famille ou de l’éducation. Certaines écoles ont déjà un programme de formation émotionnelle pour lutter contre la violence et améliorer le climat de notre société, ou tout simplement pour devenir empathique. L’intelligence émotionnelle peut apporter une réponse qui améliorera le climat de classe, permettra la gestion des conflits, développera l’empathie et nous mènera à une vie scolaire créatrice, ouverte et confiante, autant pour les enfants que pour l’enseignant. Inspiré par mes élèves, un journal filmé a été créé, le 3 Minutes qui a permis à chacun d’expérimenter un « savoir être ». Une aventure dans laquelle les élèves se sont révélés surprenants, intéressés et drôles, ont pu faire de belles expériences et des progrès. La vie de l’école n’est pas un long fleuve tranquille ; nous avons parfois tangué, mais j’espère avoir pu consolider un peu leur embarcation et la mienne.
description: Mémoire professionnel, Master of arts en enseignement spécialisé
Graphite moderated reactor heat removal project
Creators: name: DeMoss, Brant
name: Garcia, Joseph
name: Walker, Daniel
name: Frey, Joshua
Publisher: name: F1000 Research Limited
Year: 2023

description: The purpose of the Graphite Moderated Reactor Heat Removal Capstone Project is to develop a heat removal system for a graphite moderated research reactor under emergency conditions. Emergency conditions in this scenario are defined as a loss of external power and coolant. The heat removal system should be operable by a small team such as a Nuclear Disablement Team or a similar civilian entity. The process for doing so consisted of selecting a reactor design to use, which for this project was the MAGNOX design. This was followed by analyzing data on available MAGNOX reactors from the United Kingdom. While all reactor data were accounted for, the Calder Hall Power Station was used as the initial model to downscale to a 5MWe reactor. Using the previously mentioned reactors, linear extrapolations could be performed in order to conduct calculations to find thermal to electric efficiency and fuel efficiency. Various models of the downscaled core were then created in SolidWorks to be used in ATTILA4MC simulations. The current stage of the project is a working model of the downscaled core operating in steady state. This allows for the selection of different conditions to be introduced to the core to model how heat transfer will change.
Heat removal from a graphite moderated reactor
Creators: name: DeMoss, Brant
name: Garcia, Joseph
name: Walker, Daniel
name: Frey, Joshua
Publisher: name: F1000 Research Limited
Year: 2023

description: The purpose of the Graphite Moderated Reactor Heat Removal Capstone Project is to develop a heat removal system for a graphite moderated research reactor under emergency conditions. Emergency conditions in this scenario are defined as a loss of external power and coolant. The heat removal system should be operable by a small team such as a Nuclear Disablement Team or a similar civilian entity. The process for doing so consisted of selecting a reactor design to use, which for this project was the MAGNOX design. This was followed by analyzing data on available MAGNOX reactors from the United Kingdom. While all reactor data were accounted for, the Calder Hall Power Station was used as the initial model to downscale to a 5MWe reactor. Using the previously mentioned reactors, linear extrapolations could be performed in order to conduct calculations to find thermal to electric efficiency and fuel efficiency. Various models of the downscaled core were then created in SolidWorks to be used in ATTILA4MC simulations. The current stage of the project is a working model of the downscaled core operating in steady state. This allows for the selection of different conditions to be introduced to the core to model how heat transfer will change.
Inferring Quadrupolar Dynamo Mode from Sunspot Statistics
Creators: name: Kitchatinov, Leonid
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: Observations of long-term north-south asymmetry in solar activity demand the equator-symmetric (quadrupolar) mode be present in the solar magnetic field in line with the dominant antisymmetric (dipolar) mode. This paper proposes treating the sunspot area as a proxy for subsurface toroidal magnetic flux to infer the quadrupolar mode of the solar dynamo from sunspot data. Toroidal pseudo-fluxes (PF) in the northern and southern hemispheres are defined as a signed sunspot area with plus or minus sign prescribed to them in accord with the Hale's sunspot polarity rules. Statistical correlation analysis and wavelet analysis of so-defined PFs reveal quadrupolar oscillations with a period of about 16 yr and amplitude of about 0.17 relative to the amplitude of the dominant 22-yr dipolar mode.
description: 5 pages, 6 figures
On Spectral Evolution and Temporal Binning in Gamma-Ray Bursts
Creators: name: Burgess, J. Michael
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The understanding of the prompt $γ$-ray spectra of gamma-ray bursts (GRBs) is of great importance to correctly interpreting the physical mechanisms that produce the underlying event as well as the structure of the relativistic jet from which the emission emanates. Time-resolved analysis of these spectra is the main method of extracting information from the data. In this work, several techniques for temporal binning of GRB spectra are examined to understand the systematics associated with each with the goal of finding the best method(s) to bin lightcurves for analysis. The following binning methods are examined: constant cadence (CC), Bayesian blocks (BB), signal-to-noise (S/N) and Knuth bins (KB). I find that both the KB and BB methods reconstruct the intrinsic spectral evolution accurately while the S/N method fails in most cases. The CC method is accurate when the cadence is not too coarse but does not necessarily bin the data based on the true source variability. Additionally, the integrated pulse properties are investigated and compared to the time-resolved properties. If intrinsic spectral evolution is present then the integrated properties are not useful in identifying physical and cosmological properties of GRBs without knowing the physical emission mechanism and its evolution.
title: Energy-efficient IoT by Continual Learning for Data Reduction in Wireless Sensor Networks
Creators: name: Falzberger, Alexander
Publisher: name: TU Wien
Year: 2023
Subjects: subject: IoT
subject: wireless sensor networks
subject: prediction-based data reduction
subject: neural networks
subject: continual learning
subject: environmental monitoring

description: The Internet of Things (IoT) is becoming increasingly prevalent in our daily lives, with sensor devices providing the ability to sense and act on the environment. However, these sensor nodes are often resource-constrained, relying on batteries as an energy source, and constrained by wireless communication, which results in higher energy consumption and network congestion. Reducing required network communication in these devices increases their lifetime, reduces maintenance costs, and preserves network resources. To tackle this challenge, we propose SenseReduce, an open-source framework for prediction-based data reduction with continual learning and continuous deployment of prediction models in IoT environments. The framework enables using neural networks as multivariate prediction models, which can significantly reduce the required communication by predicting future sensor measurements with high accuracy. To evaluate the performance of the proposed framework, we conduct a parameter study based on the use case of air temperature monitoring. We design three neural networks with varying architectural and computational complexities using hyperparameter optimization and run multiple simulation scenarios using different training datasets and parameter configurations. The quantitative evaluation of the simulation results demonstrates the effectiveness of SenseReduce in reducing the required messages by up to 38% and the amount of transferred data by up to 22% compared to a baseline using trend extrapolation. Continuous model updates reduce the total data transferred in scenarios with sparse training data and improve model performance over time. Additionally, our simulations show that the effectiveness of prediction-based data reduction highly depends on the context, including measurement frequency, threshold metric, and model architecture. Overall, we provide several recommendations for future applications, particularly for air temperature monitoring.
Une entrée esthétique pour aborder les mathématiques
Creators: name: Mahmoudi, Esther
Publisher: name: Unknown
Year: 0
Subjects: subject: entrée ludique
subject: re-création
subject: figures géométriques superposées
subject: reproduction
subject: fonctions instrumentales

description: Je désirais trouver une entrée différente dans l’apprentissage, une entrée par la créativité et l’esthétique, une alternative ludique mais qui ne s’éloigne pas de l’objectif : apprendre. J’ai trouvé avec la reproduction de figures géométriques, un outil créé par Thierry Dias pour apprendre à raisonner dans le domaine des mathématiques, l’occasion de mettre des élèves de 5ème CYT, dits « à besoins renforcés », dans une situation d’apprentissage captivante et concrète. Favoriser l’attention, la mémorisation et le jeu de langage peuvent être des instruments fonctionnels pour le développement du raisonnement. L’envie de recréer un lien avec les mathématiques, en présentant des figures complexes avec des formes superposées et en couleurs, était mon objectif premier. J’ai cherché des figuressur mon parcours individuel, je les ai tracées dans un cahier de croquis me mettant à mon niveau dans la situation de reproduction qui sera celle de l’élève. Mon second objectif était d’utiliser les reproductions des élèves pour illustrer leurs capacités ou leurs difficultés afin d’enrichir les échanges avec les adultes responsables de la scolarité des enfants. De façon générale, l’analyse des résultats de l’expérimentation est encourageante. Les élèves ont été séduits par les figures géométriques proposées. Mon cahier de croquis, souvent feuilleté et consulté, a joué un rôle dans leur motivation et ils se sont lancés dans le travail de reproduction avec le même enthousiasme que j’ai ressenti en les créant. Le questionnement suscité par l’observation de mes élèves m’a passionnée, j’ai consulté des ouvrages théoriques et cet apport a alimenté ma réflexion. J’ai pu transmettre aux autres intervenants mon intérêt pour les reproductions de mes élèves et ceux-ci ont répondu favorablement. Toutefois cet outil est à manier prudemment car, à cause du raccourci de l’image, il risque de fixer un état. En tant qu’outil d’évaluation, la reproduction de figures donne une image de leur fonctionnement à un moment donné et doit être complétée avec d’autres méthodes.
description: Mémoire professionnel, Master of arts en enseignement spécialisé
A computational study of accelerating, steady and fading negative streamers in ambient air
Creators: name: Guo, Baohong
name: Li, Xiaoran
name: Ebert, Ute
name: Teunissen, Jannis
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: We study negative streamers in ambient air using a 2D axisymmetric fluid model. Depending on the background electric field, we observe accelerating, steady and fading negative streamers. Fading occurs in low background fields, when negative streamers lose their field enhancement and when their velocities become comparable to their maximal electron drift velocities. Our focus is on the steady propagation mode, during which streamer properties like radius and velocity hardly change. However, this mode is unstable, in the sense that a small change in conditions leads to acceleration or deceleration. We observe steady negative streamers in background fields ranging from 9.19 kV/cm to 15.75 kV/cm, indicating that there is no unique steady propagation field (or stability field). Another finding is that steady negative streamers are able to keep propagating over tens of centimeters, with only a finite conductive length behind their heads, similar to steady positive streamers. Approximately linear relationships are observed between the optical diameter and properties like the streamer velocity and the streamer head potential. From these linear relations, we obtain rough lower bounds of about 0.27 mm to 0.35 mm for the minimal optical diameter of steady negative streamers. The lowest background field in which a steady negative streamer could be obtained is 9.19 kV/cm. In contrast, steady positive streamers have recently been obtained in a background field as low as 4.05 kV/cm. We find that the properties of steady negative and positive streamers differ significantly. For example, for steady negative streamers the ratio between streamer velocity and maximal electron drift velocity ranges from about 2 to 4.5, whereas for steady positive streamers this ratio ranges from about 0.05 to 0.26.
Dissipative superfluid mass flux through solid 4He
Creators: name: Vekhov, Ye.
name: Hallock, R. B.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The thermo-mechanical effect in superfluid helium is used to create an initial chemical potential difference, $Δμ_0$, across a solid $^4$He sample. This $Δμ_0$ causes a flow of helium atoms from one reservoir filled with superfluid helium, through a sample cell filled with solid helium, to another superfluid-filled reservoir until chemical potential equilibrium is restored. The solid helium sample is separated from each of the reservoirs by Vycor rods that allow only the superfluid component to flow. With an improved technique, measurements of the flow, $F$, at several fixed solid helium temperatures, $T$, have been made as function of $Δμ$ in the pressure range 25.5 - 26.1 bar. And, measurements of $F$ have been made as a function of temperature in the range $180 < T < 545$~mK for several fixed values of $Δμ$. The temperature dependence of the flow above $100$~mK shows a reduction of the flux with an increase in temperature that is well described by $F = F_0^*[1 - a\exp(-E/T)]$. The non-linear functional dependence $F \sim (Δμ)^b$, with $b < 0.5$ independent of temperature but dependent on pressure, documents in some detail the dissipative nature of the flow and suggests that this system demonstrates Luttinger liquid-like one-dimensional behavior. The mechanism that causes this flow behavior is not certain, but is consistent with superflow on the cores of edge dislocations.
description: 11 pages, 14 figures
Accounting for Cosmic Variance in Studies of Gravitationally-Lensed High-Redshift Galaxies in the Hubble Frontier Field Clusters
Creators: name: Robertson, Brant E.
name: Ellis, Richard S.
name: Dunlop, James S.
name: McLure, Ross J.
name: Stark, Daniel P.
name: McLeod, Derek
Publisher: name: arXiv
Year: 2014
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this {\it Letter}, we demonstrate there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ~35% at redshift z~7 to >~65% at z~10. Previous studies of high redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.
description: 5 pages, 3 figures. Version accepted by ApJL
Apropiación, identidad y sentido de lugar en el espacio público de la av. Álvaro Obregón en la ciudad de Mexicali, B.C. /
Creators: name: Díaz Sánchez, Carolina
Publisher: name: Universidad Autónoma de Baja California, Mexicali.
Year: 2023
Subjects: subject: Espacios públicos||Aspectos sociales||México AvÁlvaro Obregón||Mexicali, Baja California||Tesis y disertaciones académicas
subject: NA9053.S6 D53 2023

description: El espacio público es un componente indispensable dentro de las estructuras urbanas, se le considera espacio democrático, inclusivo y de libre tránsito, en él, los individuos se reconocen con otros y con el entorno inmediato y dan lugar, en dicho proceso, a la apropiación y a la construcción de identidad. En una ciudad fronteriza como Mexicali, cuya traza urbana se basa en la retícula norteamericana, las calles constituyen el principal espacio público de la ciudad, pero son también un espacio dificultoso para la población ya que dichas vialidades responden principalmente a la demanda vehicular y dejan de lado las amenidades para recorrerlas a pie o en otros medios de movilidad no motorizada. Aun con este panorama, es común advertir una práctica recurrente, los habitantes de la ciudad toman las calles como escenarios para múltiples actividades de carácter público, social o deportivo ante la deficiencia de la oferta para tales efectos. La Avenida Álvaro Obregón es una de esas vialidades que acompaña a la ciudad de Mexicali desde su origen y en poco más de 100 años ha sido testigo de distintas formas de apropiación e interacciones entre los habitantes y sus edificaciones aun cuando el crecimiento de la ciudad se ha alejado de esta calle y la oferta de espacios de entretenimiento, generalmente privada y que obliga al consumo, supera a la que esta avenida pueda ofrecer. Por lo tanto, se considera importante identificar los elementos tangibles e intangibles que permiten que los procesos de apropiación, identidad y apego se manifiesten en la Av. Álvaro Obregón y la factibilidad de que estos sean replicables en otras vialidades de la ciudad a fin de incrementar el carácter público en las calles de Mexicali.
Nuclear inputs of key iron isotopes for core-collapse modeling and simulation
Creators: name: Nabi, Jameel-Un
name: Tawfik, Abdel Nasser
Publisher: name: arXiv
Year: 2014
Subjects: subject: Nuclear Theory (nucl-th)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: From the modeling and simulation results of presupernova evolution of massive stars, it was found that isotopes of iron, $^{54,55,56}$Fe, play a significant role inside the stellar cores, primarily decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture processes thereby reducing the pressure support. The neutrinos produced, as a result of these capture processes, are transparent to the stellar matter and assist in cooling the core thereby reducing the entropy. The structure of the presupernova star is altered both by the changes in $Y_{e}$ and the entropy of the core material. Here we present the microscopic calculation of Gamow-Teller strength distributions for isotopes of iron. The calculation is also compared with other theoretical models and experimental data. Presented also are stellar electron capture rates and associated neutrino cooling rates, due to isotopes of iron, in a form suitable for simulation and modeling codes. It is hoped that the nuclear inputs presented here should assist core-collapse simulators in the process of fine-tuning of the $Y_{e}$ parameter during various phases of presupernova evolution of massive stars. A reliable and accurate time evolution of this parameter is a possible key to generate a successful explosion in modeling of core-collapse supernovae.
description: 17 pages, 6 figures and 5 tables
New Superbridge Index Calculations from Non-Minimal Realizations
Creators: name: Shonkwiler, Clayton
Publisher: name: arXiv
Year: 2022
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57K10 (primary), 53A04 (secondary)

description: Previous work used polygonal realizations of knots to reduce the problem of computing the superbridge number of a realization to a linear programming problem, leading to new sharp upper bounds on the superbridge index of a number of knots. The present work extends this technique to polygonal realizations with an odd number of edges and determines the exact superbridge index of many new knots, including the majority of the 9-crossing knots for which it was previously unknown and, for the first time, several 12-crossing knots. Interestingly, at least half of these superbridge-minimizing polygonal realizations do not minimize the stick number of the knot; these seem to be the first such examples. Appendix A gives a complete summary of what is currently known about superbridge indices of prime knots through 10 crossings and Appendix B gives all knots through 16 crossings for which the superbridge index is known.
description: 23 pages, 4 figures, 3 appendices
Modelización y valuación de los servicios ecosistémicos hidrológicos del acuífero Valle de Mexicali como instrumento de gobernanza /
Creators: name: Cital Morales, Frida Sofía
Publisher: name: Universidad Autónoma de Baja California, Mexicali.
Year: 2023
Subjects: subject: Ingeniería hidráulica Instrumentos||Acuífero||Valle de Mexicali||Tesis y disertaciones académicas||lemb
subject: TC177 C58 2023

description: La escasez del agua se considera el principal problema para el desarrollo de la humanidad y uno de los principales desafíos del siglo XXI, por ello el estudio del recurso hídrico en ambientes controlados y modificados antropogénicamente es de suma importancia, como lo son las aguas subterráneas, que representan el 97% de la disponibilidad hídrica global, su conocimiento es el primer paso a la gestión integral de las aguas subterráneas. En la presente investigación se planteó como objetivo aportar elementos de gobernanza en el acuífero del Valle de Mexicali el cual se encuentra en condición de sobreexplotación, mediante el análisis de la gobernanza actual, la evaluación hidrogeológica y la valuación los servicios ecosistémicos hidrológicos que el acuífero provee en la zona de estudio. Para ello se estudiaron 1) la gobernanza del agua subterránea, que se analizó mediante los indicadores de Demanda Relativa de Agua y el Índice de Cambio de Almacenamiento y, del análisis de los marcos regulatorios normativo, institucional, hidráulico y ambiental, además de los mecanismos de participación social, 2) el análisis de las condiciones hidrogeológicas, para lo cual se construyó y calibró un modelo hidrogeológico numérico; y 3) los servicios ecosistémicos hidrológicos que proveen las aguas subterráneas mediante métodos directos e indirectos. Como resultado se encontró que, el uso del agua en la zona de estudio no es sustentable, abundan los problemas de gobernanza y consecuencias de la sobreexplotación, falta financiamiento para el monitoreo y las mediciones de las extracciones de agua subterránea y aumente la capacidad técnica y humana de las agencias y organizaciones locales. De la simulación del modelo hidrogeológico para el año 2018-2019 y 16 escenarios predictivos de gestión y manejo del agua; se encontró que el escenario con mayor efecto positivo es el de disminución de la extracción en un 38.4% que generaría en un incremento del nivel freático de hasta 2 m anuales, en cambio, los escenarios de reducciones de agua superficial del Río Colorado simuladas como cambios en la recarga de 0.08 a 10.8% y compensación de estos volúmenes con agua subterránea generarían cambios de entre -0.22 y -3.07 m anuales en el nivel freático. La valuación de los servicios ecosistémicos se estimaron en 90’844,251 millones de dólares anuales. La presente ivestigación aportó elementos de gobernanza del agua, mediante la realización de un modelo hidrogeológico que permitió conocer los procesos actuales del balance e identificar los servicios ecosistémicos hidrológicos que provee. Este elemento podría ser utilizado para la toma de decisiones basadas en ciencia y las políticas publicas en materia de agua.
Lorentzian Vacuum Transitions with a Generalized Uncertainty Principle
Creators: name: Garcia-Compean, H.
name: Mata-Pacheco, D.
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The vacuum transition probabilities between to minima of a scalar field potential in the presence of gravity are studied using the Wentzel-Kramers-Brillouin approximation. First we propose a method to compute these transition probabilities by solving the Wheeler-DeWitt equation in a semi-classical approach for any model of superspace that contains terms of squared as well as linear momenta in the Hamiltonian constraint generalizing in this way previous results. Then we apply this method to compute the transition probabilities for a Friedmann-Lemaitre-Robertson-Walker metric with positive and null curvature and for the Bianchi III metric when the coordinates of minisuperspace obey a Standard Uncertainty Principle and when a Generalized Uncertainty Principle is taken into account. In all cases we compare the results and found that the effect of considering a Generalized Uncertainty Principle is that the probability is enhanced at first but it decays faster so when the corresponding scale factor is big enough the probability is reduced. We also consider the effect of anisotropy and compare the result of the Bianchi III metric with the flat FLRW metric which corresponds to its isotropy limit and comment the differences with previous works.
description: 33 pages, 3 figures. All sections were improved. Section 6 added. References added
Les constructions géométriques dans l'espace pour l'apprentissage de la géométrie
Creators: name: Serment, Jimmy
Publisher: name: Unknown
Year: 0
Subjects: subject: Espace
subject: Géométrie
subject: Expérimentations
subject: Constructions
subject: Apprentissage
subject: Raisonnement

description: Résumé – L’enseignement de la géométrie dans l’espace est souvent délaissé au secondaire 1 (élèves âgés de onze à quinze ans actuellement), faute de moyens mis à disposition des élèves. Cette recherche tente d’observer et d’analyser des élèves de l’enseignement spécialisé dans des situations problèmes concrètes en géométrie de l’espace. En partant de l’hypothèse que ces jeunes en difficulté sont capables d’entrer et de réaliser des problèmes complexes en construction géométrique, j’ai constaté que ces élèves ont des ressources étonnantes pour atteindre les objectifs demandés. Ces ressources sont différentes des élèves dits « normaux », ils peuvent utiliser, par exemple, leurs intuitions pour résoudre une situation problème difficile. Malheureusement pour ces jeunes, les intuitions ne sont pas reconnues à l’école comme un bon moyen de réaliser une activité. Ces intuitions sont souvent bonnes, mais elles demandent à être vérifiées, stabilisées afin que les jeunes puissent aller plus loin dans leurs apprentissages. L’intuition est une entrée possible, mais elle doit déboucher sur des connaissances concrètes. Les tâches complexes réalisées vont nourrir l’intuition des jeunes et ils pourront avoir une intuition plus pertinente dans de futurs exercices. En plus de ce rapport entre intuition et expériences, j’ai pu observer l’importance d’une dialectique entre expériences et théorie (Dias, 2008). Il est essentiel d’amener ces élèves à faire des liens entre les exercices proposés et la théorie afin que leurs apprentissages ne se fassent pas que superficiellement. Une autre spécificité de ces élèves est le besoin de matériel pour accomplir des tâches complexes. Il est indispensable de pouvoir faire manipuler, construire pour étayer l’apprentissage de ces jeunes en difficulté, car leur capacité de se représenter les problèmes mentalement est moins développée par rapport aux autres jeunes de l’école traditionnelle.
description: Mémoire professionnel, Master of arts en enseignement spécialisé
Evaluación de la movilidad sustentable :
Creators: name: Santos Gómez, Ma. De Los Ángeles
Publisher: name: Universidad Autónoma de Baja California, Mexicali.
Year: 2023
Subjects: subject: Transporte urbano Aspectos ambientales||México||Mexicali, Baja California||Tesis y disertaciones académicas||lemb
subject: HE311.M6 S36 2018

description: La movilidad y el transporte urbano influyen en el desarrollo de una ciudad o región, pero también forman parte de la problemática urbana y ambiental. Para ello, se requiere actualizar el marco de la planeación urbana y del territorio que considere la relación entre transporte y cuidado del ambiente a partir de información sobre patrones de movilidad y sus impactos. El modelo clásico de demanda de transporte permite recabar la información a través de cuatro pasos: generación, atracción, distribución y asignación de viajes, sin embargo, no contempla el aspecto ambiental de consumo energético y contaminación. El modelo tradicionalmente ha sido planteado a partir de estudios de origen y destino (O-D) basados en encuestas que representan un elevado costo de elaboración y que se convierte en una limitante para su actualización, condición que exige la dinámica actual de las ciudades y zonas metropolitanas. Por lo tanto, el objetivo de esta investigación fue desarrollar una alternativa metodológica de menor costo y fácil actualización, que se traduce en la elaboración de una matriz O-D basada en información estadística oficial de población y vivienda y de unidades económicas para las ciudades, que para el caso de estudio fue la ciudad de Mexicali en 2010. Dicha información sirvió de base para elaborar una matriz O-D de viajes al empleo y el planteamiento de los modelos de transporte, movilidad, consumo energético y emisiones contaminantes. Entre los resultados obtenidos; se realizaron 597,706 traslados diarios de personas en días hábiles con motivo de traslado hogar-empleo (HE) y empleo-hogar (EH), con un recorrido promedio de 6.03 km por viaje, un consumo de combustible promedio de 17.61 litros (lt) y 22.08 kilogramos (kg) de dióxido de carbono equivalente (CO2e) generados en cada viaje. Esta información puede ser consultada por los tomadores de decisiones en el proceso de planeación urbana
Constraining axion-like particles with the diffuse gamma-ray flux measured by the Large High Altitude Air Shower Observatory
Creators: name: Mastrototaro, Leonardo
name: Carenza, Pierluca
name: Chianese, Marco
name: Fiorillo, Damiano F. G.
name: Miele, Gennaro
name: Mirizzi, Alessandro
name: Montanino, Daniele
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The detection of very high-energy neutrinos by IceCube experiment supports the existence of a comparable gamma-ray counterpart from the same cosmic accelerators. Under the likely assumption that the sources of these particles are of extragalactic origin, the emitted photon flux would be significantly absorbed during its propagation over cosmic distances. However, in the presence of photon mixing with ultra-light axion-like-particles (ALPs), this expectation would be strongly modified. Notably, photon-ALP conversions in the host galaxy would produce an ALP flux which propagates unimpeded in the extragalactic space. Then, the back-conversion of ALPs in the Galactic magnetic field leads to a diffuse high-energy photon flux. In this context, the recent detection of the diffuse high-energy photon flux by the Large High Altitude Air Shower Observatory (LHAASO) allows us to exclude at the $95\%$ CL an ALP-photon coupling $g_{aγ}\gtrsim 3.9-7.8 \times 10^{-11}~\mathrm{GeV^{-1}}$ for $m_{a}\lesssim 4\times10^{-7}~\mathrm{eV}$, depending on the assumptions on the magnetic fields and on the original gamma-ray spectrum. This new bound is complementary with other ALP constraints from very-high-energy gamma-ray experiments and sensitivities of future experiments.
description: 17 pages, 14 figures
Electron Spin Decoherence in Silicon Carbide Nuclear Spin Bath
Creators: name: Yang, Li-Ping
name: Burk, Christian
name: Widmann, Mattias
name: Lee, Sang-Yun
name: Wrachtrup, Jörg
name: Zhao, Nan
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this paper, we study the electron spin decoherence of single defects in silicon carbide (SiC) nuclear spin bath. We find that, although the natural abundance of $^{29}\rm{Si}$ ($p_{\rm{Si}}=4.7\%$) is about 4 times larger than that of $^{13}{\rm C}$ ($p_{\rm{C}}=1.1\%$), the electron spin coherence time of defect centers in SiC nuclear spin bath in strong magnetic field ($B>300~\rm{Gauss}$) is longer than that of nitrogen-vacancy (NV) centers in $^{13}{\rm C}$ nuclear spin bath in diamond. The reason for this counter-intuitive result is the suppression of heteronuclear-spin flip-flop process in finite magnetic field. Our results show that electron spin of defect centers in SiC are excellent candidates for solid state spin qubit in quantum information processing.
description: 6 pages, 6 figures
Factores de permanencia de las microempresas del sector comercio de Mexicali, Baja California /
Creators: name: Sandoval Sánchez, Ana Jazmín
Publisher: name: Universidad Autónoma de Baja California, Mexicali.
Year: 2023
Subjects: subject: Pequeñas empresas||Finanzas Software||Tesis y disertaciones académicas||lemb
subject: HG4027.7 S35 2022

description: La presente investigación tiene como objetivo diseñar un modelo que permita la permanencia de las microempresas comerciales en Mexicali, B.C. El diseño de investigación es explicativo, no experimental, transversal. El estudio será correlacional y multivariable. Se utilizó como instrumento de medición un cuestionario sometido a pruebas estadísticas a través del alfa de cronbach para determinar su fiabilidad, mismo que fue aplicado a 426 microempresas comerciales de Mexicali, Baja California. Con base en el diagnóstico realizado y la revisión de la literatura sobre el tema, se determinaron las variables para generar un modelo de permanencia de las microempresas, mismo que considera factores internos y factores externos. Los factores internos que se consideraron son educación financiera del microempresario, gestión financiera, acceso a financiamiento, gestión de los recursos humanos, gestión de la mercadotecnia, gestión de las tecnologías, estructura interna definida y formalización. En tanto, los factores externos están representados por efectos legales, políticas económicas, inseguridad y mercado.