Hasil untuk "General Works"

David Maibach, Jann Zosso

Balance flux laws of asymptotic symmetries in general relativity provide fully non-perturbative constraint equations on gravitational strain. They have proven useful for constructing numerical gravitational waveforms and for characterizing gravitational memory. As the precision of current and future detectors continues to improve, such constraints become increasingly important for high-precision tests of gravity, including searches for deviations from general relativity. This motivates a systematic understanding of analogous balance laws in theories beyond general relativity. In this work, we investigate the existence and structure of flux laws at null infinity in diffeomorphism-invariant extensions of general relativity. Our analysis is based on the covariant phase space formalism and the definition of conserved quantities, as presented by Wald and Zoupas. For a particularly relevant class of Horndeski theories, we derive a general expression for the flux and formulate the corresponding balance equation via the associated non-conserved charges. We cross-check our general results by comparing them with previous studies of Brans-Dicke gravity. Furthermore, we demonstrate that the employed methods extend straightforwardly to a broader class of diffeomorphism-invariant theories. The null part of the resulting flux laws associated with null memory is compared with and validated against the alternative derivation based on the Isaacson approach to gravitational radiation. Beyond the specific results obtained, this work is intended to serve as a practical guide for computing balance laws in generic diffeomorphism-invariant theories of gravity and paves the way for an in-depth comparison between the Isaacson approach and the covariant phase space formalism.

Dwinata Aprialdi, Reza Mohammadpour, Afri Fajar et al.

Abstract We study a tropical river in South‐East Sumatra, where land drainage in the coastal zone has resulted in subsidence and increased flooding risks, exacerbated by sea tides. The novelty of this research is in determining the effect of tide on the lowland drainage system for forestry in a coastal tropical region and the impact of river cleaning on flood management. Five monitoring stations were set up along the Lebong Hitam river and its primary channels to observe flow characteristics, water level, and bathymetry. The results show how the tide effects water level in the river and the adjacent drainage area with Eucalyptus plantations. Cleaning of the river had a significant effect on each station and increased the discharge and velocity by more than five times and reduced the water depth by more than 40%. In light of this research, it can be concluded that the cleaning up process improves flood risk management by decreasing the water level and increasing the discharge and velocity at each of the upstream stations. The cleaning did not have a significant effect on downstream sections of the river where sea levels control the water level in the river to a large extent. The work provides an analysis of tidal river and provides recommendations for current and future drainage and water management.

Beata Jungselius, Maja Fröjelin, Sebastian Johansson

This study offers a novel contribution by examining the micro-level dynamics of sharenting through a Nordic lens, focusing on how Swedish parents perceive, experience, and manage this increasingly common social media practice. Through thematic analysis of semi-structured interviews with twelve Swedish parents, we conceptualize the practice of sharing visual representations of children and family life on social media. The findings reveal complex and often ambiguous reasonings where parents balance a desire to document, share and interact with concerns about social expectations, integrity and future implications. While they articulate clear boundaries around what not to share (e.g., nudity, sensitive situations), their reasoning around what is acceptable to post tends to be more implicit and negotiated, pointing to unspoken norms and evolving community standards. Findings illustrate how parents navigate these dilemmas through a set of media ideologies, explicit and implicit idioms of practice developed within their communities, and influences from Nordic digital culture. By unpacking details of activities and nuanced strategies that parents employ, this study advances understanding of sharenting as a socially negotiated, culturally situated practice, contributing new insights into how digital parenting unfolds in the Nordic context. The findings highlight the need for digital platforms to support and guide responsible sharing practices that respect children’s integrity while also allowing for parental expression.

Hui Ying Yeo, Choon Hee Ong

As the backbone of Malaysia’s economy, small and medium-sized enterprises (SMEs), particularly those in the manufacturing industry, are spotlighted in times of crisis, considering the substantial risks that small businesses must overcome. SME manufacturers strive to drive productivity and enhance competitiveness amid ongoing global challenges. Sustainable manufacturing performance is a key indicator in the manufacturing industry for reviving SMEs in the recovery stage of global crises. With continuous technological advancement, industry 4.0 competencies can have significant influence on expanding the evolution of contemporary manufacturing from theoretical industry 4.0 concepts to real-world applications. There is a gap in the literature regarding the comprehensive investigation of industry 4.0 competencies collectively and their direct impact on sustainable manufacturing performance, as well as the potential moderating influence of rational culture. The research question addressed in this paper aims to provide a comprehensive overview of prevailing studies on the relationship between industry 4.0 competencies and sustainable manufacturing performance. This study references the Global Reporting Initiative and identifies relevant industry 4.0 competencies, conducting a systematic literature review to investigate the relationship between industry 4.0 competencies and sustainable manufacturing performance and the role of rational culture as a moderating variable. Examining research published between 2013 and 2023, only 33 documents satisfy the eligibility criteria. This paper carries implications for SME manufacturers and government in Malaysia, highlighting the importance of recognizing and implementing appropriate industry 4.0 competencies to improve sustainable manufacturing performance and reap associated benefits.

R. Venkatesan, C. Kumar, C. R. Balamurugan et al.

Hybrid Renewable Energy Systems (HRES) have recently been proposed as a way to improve dependability and reduce losses in grid-connected load systems. This research study suggests a novel hybrid optimization technique that regulates UPQC in order to address the Power Quality (PQ) problems in the HRES system. The load system serves as the primary link between the battery energy storage systems (BESS), wind turbine (WT), and solar photovoltaic (PV) components of the HRES system. The major objective of the study is to reduce PQ issues and make up for the load requirement inside the HRES system. The addition of an Optimized Fractional Order Proportional Integral Derivative (O-FOPID) controller improves the efficiency of the UPQC. The Crow-Tunicate Swarm Optimization Algorithm (CT-SOA), an enhanced variant of the traditional Tunicate Swarm Optimization (TSA) and Crow Search Optimization (CSO), is used to optimize the control parameters of the FOPID controller. Utilizing the MATLAB/Simulink platform, the proposed method is put into practice, and the system’s performance is assessed for sag, swell, and Total Harmonic Distortion (THD). The THD values for the PI, FOPID, and CSA techniques, respectively, are 5.9038%, 4.9592%, and 3.7027%, under the sag condition. This validates the superiority of the proposed approach over existing approaches.

Abdelmajid Said

تتناول هذه المقالة سؤال: "ما الغاية من وجود المدارس؟" وتُحاج عن أن كل جيل ملزم بالإجابة عنه بنفسه؛ وتُبيِّن أن للمدارس في المجتمعات الحديثة مهمةً متميزةً، وهي تمكين النشء من المفاهيم التي تجعلهم قادرين على تجاوز حدود تجربتهم بطرق ربما لا تكون متاحة لهم في أسرهم ومجتمعاتهم؛ وتقدم أيضًا منظورًا بديلًا للسياسات التعليمية التي ترى المدارس، في المقام الأول، أدوات للسياسات الاقتصادية؛ كما أنها تُشكك في متن كثير من العلوم الاجتماعية التي تحصر دور المدارس في إعادة الإنتاج الثقافي والاجتماعي.

Maria Rannielly de Araújo Lima Magalhães, Gabriel Huet Borges de Arruda , Cynthia Melo

A comunicação de más notícias (CMN) é um grande desafio para profissionais atuantes em unidades neonatais, cujo entraves precisam ser mais bem compreendidos. Objetivou-se descrever a experiência do processo de CMN e a capacitação para tal a partir da perspectiva dos profissionais de saúde em contexto neonatal. Realizou-se uma pesquisa qualitativa, com participação de 23 profissionais, que responderam a um roteiro de entrevista semiestruturado. Os dados foram analisados a partir do software IRaMuTeQ e de análise de conteúdo. Os resultados apresentaram que a maioria dos profissionais de saúde considera a CMN uma tarefa desafiadora no contexto neonatal; que envolve diferentes adversidades e não apenas a notícia de morte; e que eles não foram capacitados para esse processo, embora reconheçam a importância da preparação. Conclui-se a importância de formações continuadas para capacitar profissionais com habilidades técnicas e socioemocionais para a CMN, melhorando a qualidade da comunicação e relação com o paciente e família.

Yifan Cai, Tao Wang, Liu Zhao

Based on the recently proposed framework of general relativistic stochastic mechanics [{\em J. Stat. Phys.}, 190:193, 2023; {\em J. Stat. Phys.}, 190:181, 2023] and stochastic thermodynamics [{\em SciPost Physics Core} 7, 082, 2024] at the ensemble level, this work focuses on general relativistic stochastic thermodynamics at the trajectory level. The first law of stochastic thermodynamics is reformulated and the fluctuation theorems are proved on this level, with emphasis on maintaining fully general covariance and on the choice of observers.

Yu-Chen Chao, Shreyas Gokhale, Lisa Lin et al.

Emergent nonreciprocity in active matter drives the formation of self-organized states that transcend the behaviors of equilibrium systems. Integrating experiments, theory and simulations, we demonstrate that active solids composed of living starfish embryos spontaneously transition between stable fluctuating and oscillatory steady states. The nonequilibrium steady states arise from two distinct chiral symmetry breaking mechanisms at the microscopic scale: the spinning of individual embryos resulting in a macroscopic odd elastic response, and the precession of their rotation axis, leading to active gyroelasticity. In the oscillatory state, we observe long-wavelength optical vibrational modes that can be excited through mechanical perturbations. Strikingly, these excitable nonreciprocal solids exhibit nonequilibrium work generation without cycling protocols, due to coupled vibrational modes. Our work introduces a novel class of tunable nonequilibrium processes, offering a framework for designing and controlling soft robotic swarms and adaptive active materials, while opening new possibilities for harnessing nonreciprocal interactions in engineered systems.

Hui Zhang, Li-qi Tian, Shu-jing Long et al.

In recent years, the tourism industry has expanded rapidly and China will enter the mass tourism era comprehensively, with tourism becoming an important leisure lifestyle for people. However, natural disasters have the characteristics of high frequency, multiple types, wide distribution and large post-disaster losses, which often cause huge impact on tourism industry development. It is of great practical significance to explore the key factors for successful rescue of tourists after disasters. Taking the Wenchuan earthquake as an example, the article selects the Fuzzy Delphi Method and the Analytical Hierarchy Process as the data analysis method, and also randomly selects the local residents of 20 affected scenic spots as the research subjects. The results show that among the assessment dimensions, the most important dimension is prevention, followed by preparedness, response and recovery respectively. Meanwhile, among the 16 assessment indicators, the top five most valued indicators were regional emergency planning, management systems, prompt notification, publicity and education, training and emergency drill in order.

Carlos CAÑETE

En los últimos años se han planteado varias críticas al modelo de orientalismo propuesto por Edward Said. Entre ellas destacan, por ejemplo, las advertencias acerca de la existencia de discursos orientalistas en fecha muy anterior a la señalada por Said o de corrientes orientalistas, como las ibéricas, que no encajan en el modelo antagonista propuesto por aquél. Este trabajo partirá de los textos sobre el Sáhara argelino elaborados por Yves Alliaume en las décadas centrales del siglo XX para ofrecer una reinterpretación de la relación entre los discursos orientalistas y la práctica de la colonialidad en Argelia. Para ello, se centrará en las nociones de lo “bereber” y del estatus del islam entre las poblaciones locales para mostrar como la caracterización de las sociedades en el periodo colonial no partía de unas distinciones culturales netamente definidas, sino que se articulaba a través de valoraciones sociales que conectan el ámbito colonial con el metropolitano. De todo ello surge una dimensión de la antropología del norte de África raramente advertida hoy día, pero que ya fue señalada en su momento por Franz Fanon y que aparece recurrentemente en los textos del Yves Alliaume. Esta relectura social puede servir para recomponer la noción del orientalismo dentro de la noción foucaultiana de discurso que la inspiró, así como para explorar su compleja relación con la práctica de la colonialidad desde una perspectiva glocal.

Aws al.maadhidy, Noor M. Hameed

Abstract The research aims to assess the water quality of the Tharthar Canal and its suitability for human activities in the study area by conducting physical and chemical analyzes of that water and showing its suitability for human uses. The results of the study show that most of the samples in the study area are not suitable for human use, especially drinking. The total hardness, sulfate and calcium values were determined only after filtering and processing to become drinkable, while laboratory analyzes showed that they are suitable for agricultural use in all samples of the study area. Because of the importance of the research, the physical and chemical properties were addressed to find out if they were affected by the natural or human geographical characteristics and their impact on the residents of the nearby areas and their various activities to find out the problems and develop appropriate solutions that would address the problems and adopt it as a fixed water source. It became clear through the field study that the Al-Tharthar-Euphrates Canal is not approved by the population as a main water resource, but most of the residents of the areas relied on wells for their various activities, foremost of which is agriculture and drinking.

A. V. Nekhaev

The essay raises questions about the origins of altruistic behaviour. A proper understanding of such behaviours must take into account the evidence of our best biological theories, which indicate that in the animal world (including Homo Sapiens Sapiens) there is no place for genuine altruism. What we often mistakenly call ‘altruism’ is the result of selfish genes.

Obinna Umeh

There is no source for cosmic vorticity within the cold dark matter cosmology. However, vorticity has been observed in the universe, especially on the scales of clusters, filaments, galaxies, etc. Recent results from high-resolution general relativistic N-body simulation show that the vorticity power spectrum dominates over the power spectrum of the divergence of the peculiar velocity field on scales where the effective field theory of large-scale structure breaks down. Incidentally, this scale also corresponds to the scale where shell-crossing occurs. Several studies have suggested a link between shell crossing in the dark matter fluid and the vorticity generation in the universe, however, no clear proof of how it works within general relativity exists yet. We describe for the first time how vorticity is generated in a universe such as ours with expanding and collapsing regions. We show how vorticity is generated at the boundary of the expanding and collapsing regions. Our result indicates that the amplitude of the generated vorticity is determined by the jump in gradients of the gravitational potential, pressure and the expansion rate at the boundary. In addition, we argue that the presence of vorticity in the matter fields implies a non-vanishing magnetic part of the Weyl tensor. This has implications for the generation of Maxwell's magnetic field and the dynamics of clusters. The impact on accelerated expansion of the universe and the existence of causal limit for massive particles are discussed

Ariel Alberto Eiris

Emine Şeyma Kutluk

We use a trick similar to Weinberg's for adiabatic modes, in a Manton approximation for general relativity on manifolds with spatial boundary. This results in a description of the slow-time dependent solutions as null geodesics on the space of boundary diffeomorphisms, with respect to a metric we prove to be composed solely of the boundary data. We show how the solutions in the bulk space is determined with the constraints of general relativity. To give our description a larger perspective, we furthermore identify our resulting Lagrangian as a generalized version of the covariantized Lagrangian for continuum mechanics. We study the cases of 3+1 and 2+1 dimensions and show for the solutions we propose, the Hamiltonian constraint becomes the real homogeneous Monge-Ampere equation in the special case of two spatial dimensions.

Nikos Bagis

Based on previous work we consturct an equation (Lagrange equation) and relate it with a system of generalized integrals and differential equations in such a way to provide useful evaluations and connections between them.

Diana Alejandra Méndez Rojas

El artículo expone los resultados de una investigación centrada en el estudio de las trayectorias de los guatemaltecos que, apoyados por el Programa de Becas de la Fundación Rockefeller, cursaron capacitaciones avanzadas o estudios de posgrado en ciencias agrícolas en México, entre 1949 y 1976. Desde el mirador de la historia del intercambio académico, en clave transnacional, se propone que la agricultura fungió como un puente que, a través de los itinerarios de los becarios, unió dos procesos: la profesionalización de la enseñanza agrícola en México y la profesionalización de la investigación agrícola en Guatemala. Se argumenta, además, que ambos procesos formaron parte del despliegue de la revolución verde en América Latina. Esta indagación se fundamentó en la consulta de fuentes primarias, hemerografía y entrevistas.

Wefaq al-Hadabi, Hossein Nadhri

صحيحٌ أنّ الحياة تجدد، والتّجدد سرّ الوجود، وصحيحٌ أنّ الوجود لو غاسسحب عنه التّجدد فارق الحياة، لكنّ الماضي أيضا له عبقه وحيويته ووجوده الكائن فيه، وما يحتاجه تجدد فقط ليحيا حياة ثانية، ولكيلا يَهمد ويندثر، تهدف هذه الدّراسة إلى تجدد التّراث، والتّعرف على علم الاكتناه وببلوغرافية المخطوط وأثرهما في إثراء السّاحة العلميّة والثّقافيّة، يتيح هذا المفهوم بما هو علم وفنّ فرصة الكشف عن تماثل إبداعيّ في شتّى العلوم والفنونّ، بين سالف العصور وبين الواقع الحاليّ، وأثبتت الدّراسة أنّ التّراث العربيّ الإسلاميّ عبارة عن بِساطٍ زاهٍ ثريّ، نسجته أيد وأفكار مبدعة معطاء، أفرغت طاقتها وثقافتها وأدبها فيه، وكلّ تلك القرائح المُبدعة تستحق منّا الإعزاز والإكرام، فكأين من تجربة وعلم وإبداع هما طيّ للنّسيان لولا المعول على تراث الأجداد، إذ من خلاله يمكن فهم العلائق بين ما كان وما يكون، وللعرب المشرقيين يُعزى فضل إنجاب المبدعين في شتّى المجالات، ولهم قصب السّبق للإنتاج الإبداعيّ، فهمّ أمّة ولود متنوّرة خلّفت أعظم الهامات، وأسست أهمّ العلوم كذلك الفنون، وهذا ما يُثير فينا الإعجاب والتّقصي لدراسته، والنّاظر لمسار اللّغة العربيّة وأثَر مواقع وقنوات التّواصل الثّقافيّ و(التكنلوجيا) الحديثة يرى بجلاء الخطر الماحق، والمصير المُرعب الّذي قد تنحدر إليه ثقافتنا، الّذي يجعل مصيبتنا في تراثنا ولغتنا تتصاغر دونها كلّ مصيبة، ولابدّ إذا من تضافر جهود الغيارى على التّراث الثّقافيّ والدّينيّ واللّغويّ، فيعمدون لإحياء الكتب الصّفراء الغنيّة المغمورة، والاهتمام بها، ففيها علم وفنّ زاخران، هذا وقد اعتمدنا المنهج الوصفيّ وهو ما يناسبنا في بيان أهميّة التّحقيق في رفد الثّقافة، وأبنّا مدى تأثير عمل المحقِّق سِلبا وإيجابا في إثراء التّراث.

Vanilson Lemes, Anelise Reis Gaya, Adroaldo Cezar Araujo Gaya

Objetivos: verificar a confiabilidade do escore em um questionário de aptidão física autorrelatada (QAPA) em crianças de 6 a 11 anos, nas aulas de educação física não presenciais em 2020, durante o distanciamento social COVID-19 e identificar se há associação do escore no QAPA com níveis de aptidão cardiorrespiratória (APC) e índice de massa corporal (IMC) mensurados no ano 2019. Métodos: estudo longitudinal retrospectivo realizado no sul de Santa Catarina com crianças de 6 a 11 anos, 142 meninas e 146 meninos. Aplicou-se o QAPA em pais, responsáveis e alunos via Google Forms, ClassRoom e material impresso. O IMC e APC foram mensurados pelo protocolo PROESP-BR em 2019.  A análise foi realizada com teste t de student, qui-quadrado, alfa de Cronbach e modelos de equações estruturais (MEE). Resultados: O QAPA apresentou confiabilidade superior a 0,70 e parâmetros adequados no MEE (AIC/BIC: 149/151; SRMR: 0,0562; RMSEA: 0,074; CFMIN/DF: 2,558; CFI/TLI: 0,92/0,90). O escore QAPA em 2020 se associou com maior APC (b: 0,51; p: 0,001) e menor IMC no ano 2019 (b:-0,17; p: 0,001). Conclusão: O QAPA apresenta elevada confiabilidade e consistência se respondido pelos pais ou responsáveis (crianças de 6 a 8 anos) e por crianças de 9-11 anos. Crianças com um elevado escore no QAPA em 2020 apresentavam elevada APC e reduzido IMC em 2019. O QAPA é uma medida consistente e confiável para ser aplicada em pais, responsáveis das crianças de 6-8 anos e naqueles escolares com 9-11 anos.