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On the central singularity of the BTZ geometries
No full textPublisher Copyright: © 2024 American Physical Society.The nature of the central singularity of the BTZ geometries - stationary vacuum solutions of 2+1 gravity with negative cosmological constant Λ=-ℓ-2 and SO(2)×R isometry - is discussed. The essential tool for this analysis is the holonomy operator on a closed path (i.e., Wilson loop) around the central singularity. The study considers the holonomies for the Lorentz and AdS3 connections. The analysis is carried out for all values of the mass M and angular momentum J, namely, for black holes (Mℓ≥|J|) and naked singularities (Mℓ<|J|). In general, both Lorentz and AdS3 holonomies are nontrivial in the zero-radius limit revealing the presence of deltalike singularity at the origin in the curvature and torsion two-forms. However, in the cases M±J/ℓ=-n±2, with n±∈ℕ, recently identified by Giribet et al. [BPS defects in AdS3 supergravity, arXiv:2402.00171] as Bogomol'nyi-Prasad-Sommerfield configurations, the AdS3 holonomy reduces to the identity. Nevertheless, except for the AdS3 spacetime (M=-1, J=0), all BTZ geometries have a central singularity which is not revealed by local operations
Massless Rarita-Schwinger equations : Half and three halves spin solution
No full textPublisher Copyright: © 2024 SciPost Foundation. All rights reserved.Counting the degrees of freedom of the massless Rarita-Schwinger theory is revisited using Behrends-Fronsdal projectors. The identification of the gauge invariant part of the vector-spinor is thus straightforward, consisting of spins 12 and 23 . The validity of this statement is supported by the explicit solution found in the standard gamma-traceless gauge. Since the obtained systems are deterministic –free of arbitrary functions of time–we argue that the often-invoked residual gauge symmetry lacks fundamental grounding and should not be used to enforce new external constraints. The result is verified by the total Hamiltonian dynamics. We conclude that eliminating the spin- 21 mode via the extended Hamiltonian dynamics would be acceptable if the Dirac conjecture was assumed; however, this framework does not accurately describe the original Lagrangian system
Análisis de presencia de microplásticos en heces de gaviota garuma (leucophaeus modestus) en colonias de nidación del desierto de Atacama
Get PDFEn tiempos recientes, la contaminación generada por microplásticos en los mares y océanos del mundo ha sido objeto de estudio creciente, demostrando que estos contaminantes no solo afectan a los individuos, sino también a la cadena trófica a la que pertenecen. En Chile, diversas especies en la zona sur del país ya han sido impactadas por esta problemática; sin embargo, en la zona norte aún no se han realizado estudios al respecto. Por ello, el objetivo del presente estudio fue determinar la presencia de microplásticos utilizando a la gaviota garuma (Leucophaeus modestus) como especie centinela. Esta especie es particularmente adecuada para este propósito, ya que solo se reproduce y nidifica en el interior del desierto de Atacama, realizando a veces solo un viaje al día hacia la costa para alimentarse. Además, en el desierto cercano se encuentra el vertedero de la moda fast fashion o lowcost. Por lo tanto, el objetivo de este trabajo fue analizar presencia de microplásticos en heces de gaviota garuma (Leucophaeus modestus) provenientes de colonias de nidación del desierto de Atacama. Las muestras fueron recolectadas en diferentes sitios de nidación en el desierto de Atacama y sometidas a un proceso de digestión con KOH al 15% para su posterior filtración en filtros de fibra de vidrio, los cuales luego fueron visualizados bajo lupa para clasificar los microplásticos según su forma, tipo, color y tamaño. Casi en la totalidad de los filtros evaluados se encontró presencia de microplásticos, en los cuales el color predominante fue el negro (32%) y en cuanto a la forma de estos, la que más destaco fue la fibra (98%). En definitiva, gracias a la información obtenida de los análisis es posible afirmar que los microplásticos también se encuentran presentes en los sitios de nidación de la gaviota garuma al interior del desierto de Atacama.In recent times, the pollution generated by microplastics in the world's seas and oceans has been the subject of increasing study, demonstrating that these contaminants not only affect individuals, but also the trophic chain to which they belong. In Chile, several species in the southern part of the country have already been impacted by this problem; however, no studies have yet been carried out in the northern part of the country. Therefore, the objective of this study was to determine the presence of microplastics using the grey gull (Leucophaeus modestus) as a sentinel species. This species is particularly suitable for this purpose, since it only breeds and nests in the interior of the Atacama Desert, sometimes making only one trip per day to the coast to feed. In addition, the nearby desert is the dumping ground for fast fashion or lowcost fashion. Therefore, the objective of this work was to analyze the presence of microplastics in feces of grey gulls (Leucophaeus modestus) from nesting colonies in the Atacama Desert. Samples were collected from different nesting sites in the Atacama Desert and subjected to a digestion process with 15% KOH for subsequent filtration on fiberglass filters, which were then visualized under magnification to classify microplastics according to their shape, type, color and size. The presence of microplastics was found in almost all the filters evaluated, in which the predominant color was black (32%) and as for their shape, the one that stood out the most was the fiber (98%). In short, thanks to the information obtained from the analyses, it is possible to affirm that microplastics are also present in the nesting sites of the grey gull in the interior of the Atacama Desert
Genomic insights into key mechanisms for carbon, nitrogen, and phosphate assimilation by the acidophilic, halotolerant genus Acidihalobacter members
No full textPublisher Copyright: © 2024 The Author(s). Published by Oxford University Press on behalf of FEMS.In-depth comparative genomic analysis was conducted to predict carbon, nitrogen, and phosphate assimilation pathways in the halotolerant, acidophilic genus Acidihalobacter. The study primarily aimed to understand how the metabolic capabilities of each species can determine their roles and effects on the microbial ecology of their unique saline and acidic environments, as well as in their potential application to saline water bioleaching systems. All four genomes encoded the genes for the complete tricarboxylic acid cycle, including 2-oxoglutarate dehydrogenase, a key enzyme absent in obligate chemolithotrophic acidophiles. Genes for a unique carboxysome shell protein, csoS1D, typically found in halotolerant bacteria but not in acidophiles, were identified. All genomes contained lactate and malate utilization genes, but only A. ferrooxydans DSM 14175T contained genes for the metabolism of propionate. Genes for phosphate assimilation were present, though organized differently across species. Only A. prosperus DSM 5130T and A. aeolianus DSM 14174T genomes contained nitrogen fixation genes, while A. ferrooxydans DSM 14175T and A. yilgarnensis DSM 105917T possessed genes for urease transporters and respiratory nitrate reductases, respectively. The findings suggest that all species can fix carbon dioxide but can also potentially utilize exogenous carbon sources and that the non-nitrogen-fixing species rely on alternative nitrogen assimilation mechanisms
Propuesta de optimización del sistema de facturación y gestión de cobranzas en una empresa de telecomunicaciones
No full textEste proyecto busca optimizar la gestión de cobranzas en los servicios de
telecomunicaciones, abordando el incremento en la tasa de morosidad entre los
suscriptores pospago, lo cual afecta el flujo de caja y compromete la estabilidad
financiera de la compañía, generando costos adicionales por facturas impagas y
presión sobre los canales de atención al cliente.
El objetivo principal es mejorar la eficiencia del sistema de facturación y
cobranzas mediante la implementación de estrategias avanzadas de gestión de
morosidad temprana y la automatización de procesos. Para ello, se propone la
implementación de un asistente virtual basado en inteligencia artificial generativa,
con capacidades de interpretación y generación de voz, que permita ofrecer
atención personalizada las 24 horas del día a través de múltiples canales (teléfono,
aplicaciones móviles, plataformas web y WhatsApp). Esta solución facilitará la
automatización de interacciones recurrentes, reducirá significativamente la carga
operativa en los centros de atención y optimizará la resolución de consultas,
minimizando la dependencia de agentes humanos.
Adicionalmente, el proyecto evaluará la efectividad de las estrategias de
cobranza actuales (como suspensiones de servicio y recordatorios de pago) y
realizará un análisis financiero detallado, considerando tendencias de morosidad,
impacto inflacionario y costos asociados. Se espera que los resultados permitan
mejorar la estabilidad financiera de la empresa y reducir las obligaciones tributarias
derivadas de la acumulación de facturas impagas, consolidando a la organización
como líder en innovación tecnológica dentro del sector de telecomunicaciones
Occupational therapy in education in Latin America: an analysis from the Occupational Therapy in Education (TOE in Spanish) Community of Practice
No full textIntroduction: The Occupational Therapy in Education (TOE in Spanish) Community of Practice brings together occupational therapists from Latin America and the Caribbean related to the educational field. Framed in this community, it is understood that there is progress in the incursion of occupational therapy in education, but there is a lack of studies that analyze the reality of the region. Objective: Analyze the state of occupational therapy in education in Latin America and the Caribbean from the perspective of members of the TOE Community of Practice to understand its scope, challenges and opportunities. Methods: Members from Chile, Argentina, Bolivia, Colombia, Peru, Brazil, Venezuela, Mexico, Costa Rica and Panama presented the state of occupational therapy in education in their countries. This information was analyzed under a qualitative approach, adopting the content analysis method. Results: In all participating countries, the presence of the occupational therapist in special education is a constant. In some, their actions in regular inclusive education are beginning to be visible, but the existence of legislation that supports this, varies. The need to incorporate new paradigms that guide the exercise of occupational therapy was evident since in most countries the rehabilitation approach persists. Conclusions: The practice of occupational therapy in Latin America and the Caribbean is observed as eclectic; professionals use different approaches based on the needs of their educational systems and legislative opportunities. Theoretical frameworks adjusted to the realities of each country are required, followed by academic training in education and the generation of policies for occupational therapists’ incorporation into the inclusive regular system
The impact of parenting practices and family economy on psychological wellbeing and learning patterns in higher education students
No full textPublisher Copyright: © The Author(s) 2024.Background There is a large literature on the significant impact of rearing factors in the psychological development of different child’s learning patterns and wellbeing in elementary and secondary schools, but there is a scarcity of studies on to what extent those influences remain stable up to higher education. Objective In this study, parenting practices and family status were analyzed as predictors of the different learning styles, psychological difficulties, mental health factors, and academic performance, comprising the psychosocial diversity in learning (DinL) at the university classroom. Methods Using a cross-sectional design, a questionnaire was administered to a sample of 2522 students at the Complutense University of Madrid (Spain). It included a DinL scale measuring five psychological learning dimensions (coping with difficulties, effort, autonomy, Social/Physical Context, and understanding/career interest), plus several items on retrospective parenting practices, family, and sociodemographic variables. Multiple regressions and analyses of variance were conducted with the family factors as independent variables and the learning factors as dependent variables. Results Results showed parenting variables, parents’ education, and family economy as having a significant impact on psychological learning dimensions, academic performance, and especially on the students’ wellbeing and mental health status, being an important contributors to explain the DinL in the university classroom. Conclusion The results bring interesting conclusions for developmental and health psychologists when working with parents aimed at fostering wellbeing and learning strategies related to academic inclusion and achievement
Novel Antibacterial and Biocompatible Nanostructured Gels Based on One-step Synthesis as a Potential Disinfectant for Endodontic Infection Control
No full textPublisher Copyright: © 2023 American Association of EndodontistsAim: The objective of this study was to develop nanostructured gels as biocompatible intracanal disinfectants by one-step microwave radiation-assisted synthesis. Methods: Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were used as a support network, and polyethylene glycol (PEG) was used as a reducing agent. The gels were characterized by measuring the swelling ratio (SR) and rheological properties and by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The antibacterial effects of each gel were evaluated against the endodontic clinical strain Enterococcus faecalis. Then, the viability of the 21-day mature multispecies bacterial biofilm was assessed using confocal microscopy in an ex vivo model, where the biofilm was exposed to the mix of nanogels. The cell proliferation, viability, and morphology of human periodontal ligament (HPDL) cells were quantified using a real-time IncuCyte® S3 Live-Cell System. Viability was measured by confocal microscopy using an ex vivo model exposing a 21-day mature multispecies bacterial biofilm to the mix of nanogels. Results: The antibacterial activity of the gels coincided with the superficial characterization and the solubility of the gel in the growth medium. Gels with higher viscosity (327.85-980.58 Pa s), higher dissolution (42-70%SR), and lower porosity (no porosity and 611.63 nm) showed excellent antibacterial activity against E. faecalis. Despite their physicochemical characteristics, CuNPs gels showed greater effectiveness against E. faecalis.These nanostructured gels with high PVA concentrations promote HPDL cells proliferation while still exerting antibacterial properties. Mix of nanogels showed an increase non-viable cells biomass from at of application. Conclusions: The use of biocompatible polymers influences the physicochemical, bactericidal, and cytotoxic response, making these materials potential disinfectant agents against resistant bacteria with good biocompatibility and improved HPDL cells proliferation
Aberrant brain language network in schizophrenia spectrum disorder: a systematic review of its relation to language signs beyond symptoms.
No full textPublisher Copyright: Copyright © 2024 Alonso-Sanchez, Z-Rivera, Otero, Portal, Cavieres and Alfaro-Faccio.BackgroundLanguage disturbances are a core feature of schizophrenia, often studied as a formal thought disorder. The neurobiology of language in schizophrenia has been addressed within the same framework, that language and thought are equivalents considering symptoms and not signs. This review aims to systematically examine published peer-reviewed studies that employed neuroimaging techniques to investigate aberrant brain-language networks in individuals with schizophrenia in relation to linguistic signs.MethodsWe employed a language model for automatic data extraction. We selected our studies according to the PRISMA recommendations, and we conducted the quality assessment of the selected studies according to the STROBE guidance.ResultsWe analyzed the findings from 37 studies, categorizing them based on patient characteristics, brain measures, and language task types. The inferior frontal gyrus (IFG) and superior temporal gyrus (STG) exhibited the most significant differences among these studies and paradigms.ConclusionsWe propose guidelines for future research in this field based on our analysis. It is crucial to investigate larger networks involved in language processing, and language models with brain metrics must be integrated to enhance our understanding of the relationship between language and brain abnormalities in schizophrenia
