Hasil untuk "Geography (General)"

José M. M. Senovilla

The junction conditions for general theories of gravity based on actions that depend on arbitrary functions of the curvature scalar invariants (including differential invariants) are obtained using the distributional formalism. In case of the existence of thin shells, a general expression for the shell energy-momentum tensor is presented. Generalized Israel equations are also obtained. The conditions for a proper matching, without shells, are derived. The main results are: (i) shells arise if the $m$th-covariant derivative of the Riemann tensor is continuous at the matching hypersurface, where $m$ is the maximum order of differentiation appearing in the Lagrangian density; (ii) a proper junction without thin shells requires further that the $(m+1)$-th derivative be also continuous, (iii) theories with $m=0$ that are quadratic in the scalar curvature invariants are special and unique for they allow for discontinuities of the Riemann tensor resulting in the existence of thin shells and {\em gravitational double layers} and (iv) General Relativity and $F(R)$ theories are extraordinary theories that admit shells of curvature (i.e. impulsive gravitational waves) because other theories require the absence of jumps of the second fundamental form across the matching hypersurface. For proper junctions, the continuity across the matching hypersurface of the normal components of the energy-momentum tensor is proven to be a {\em universal} property, independently of the field equations, thereby providing important necessary conditions for any matching in any gravitational theory. All results are derived for a minimal coupling with the matter, but the strategy would be analogous for more general couplings.

Miguel Alcubierre

I present a review of the Dirac equation in general relativity. Although the generalization of the Dirac equation to a curved spacetime is well known, it is not usually part of the standard toolkit of techniques known to people working on classical general relativity. Recently, there has been some renewed interest in studying solutions of the Einstein--Dirac system of equations, particularly in the context of the so-called ``Dirac stars''. Motivated by this, here I present a review of the Dirac equation in general relativity, starting from Minkowski spacetime, and then considering the Lorentz group and the tetrad formalism in order to generalize this equation to the case of a curved spacetime. I also derive the form of the Dirac equation and its associated stress--energy tensor for the case of the 3+1 formalism of general relativity, which can be useful for the study of the evolution of the Dirac field in a dynamical spacetime.

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.

Dominik Porczyński

W artykule autor podejmuje problem prowadzenia badań dawnego pogranicza Galicji i Królestwa Polskiego na przykładzie projektu zrealizowanego na przełomie 2021 i 2022 roku. Ze względu na złożoność problemu postępowanie wymaga integracji tradycji badań pogranicza z podejściami skoncentrowanymi na eksplorowaniu relacji przeszłości z teraźniejszością. Konieczne jest dotarcie do perspektyw aktorów zewnętrznych i wewnętrznych, gromadzenie danych przestrzennych, materialnych, narracyjnych i ucieleśnionych, odwołanie się do wartości, postaw, wytworów oraz praktyk. W tekście omówione zostało podejście zainspirowane koncepcją etnografii wielostanowiskowej, uwzględniającej mobilność mieszkanek i mieszkańców badanego obszaru oraz uwikłanie zewnętrznych struktur władzy. Autor wskazał, w jaki sposób perspektywa ta może integrować różnego rodzaju techniki: analizę map i dokumentów, obserwacji, wywiadów oraz spacerów badawczych w celu wytworzenia bogatych, wzajemnie wspierających się danych, umożliwiających jak najlepsze zrozumienie przedmiotu badań.

CHEN Minghua, SHI Nan, ZHANG Bianxiu, XIE Linxiao

[Objective] The purpose of this study was to evaluate the performance of green and low-carbon development in the Major Strategic Regions of China, analyze its spatiotemporal differentiation characteristics and dynamic change, and provide a scientific basis and decision-making reference for promoting high-quality regional development in a coordinated manner. [Methods] Based on the Global-Luenberger index of the super-efficiency EBM model, this study scientifically evaluated the green and low-carbon development performance of China’s Major Strategic Regions from 2012 to 2020. Dagum Gini coefficient, variance decomposition, and traditional and spatial kernel density estimation were used to reveal the spatiotemporal differentiation, dynamic change, and long-term transfer trend. [Results] (1) During the sample study period, the performance of green and low-carbon development in the Major Strategic Regions has been improved, showing the regional disequilibrium characteristics of Guangdong-Hong Kong-Macao Greater Bay Area > Chengdu-Chongqing > Beijing-Tianjin-Hebei > Yangtze River Delta > Yellow River Basin > the middle reaches of the Yangtze River. (2) The spatial difference of green and low-carbon development performance in the Major Strategic Regions was small, showing a trend of decline and then rising over time. Supervariable density difference was the main source of spatial difference. Structural differences mainly depended on technological progress differences, input factors, and undesired output productivity differences. Further subdividing the factors, environmental pollution control productivity differences and net carbon emission reduction productivity differences were the main driving forces for regional disparities in green and low-carbon development performance. (3) The green and low-carbon development performance of the Major Strategic Regions was generally high, but there was a trend of spatial polarization. The green and low-carbon development of all regions was manifested as low-performing cities moved upward, medium-performing cities showed sustainability, and high-performing cities moved downward, and the overall distribution characteristics were reversed. When considering the spatial conditions, the positive spillover effect of neighboring cities in the Yellow River Basin, the middle reaches of the Yangtze River Delta, and the Yangtze River Economic Belt was significant, but the spatial spillover effect of the Guangdong-Hong Kong-Macao Greater Bay Area and Chengdu-Chongqing was not obvious, and the “beggar-thy-neighbor” phenomenon existed in the Beijing-Tianjin-Hebei. [Conclusion] In order to establish a new pattern of green and low-carbon development led by the Major Strategic Regions, it is necessary to rationally optimize the spatial layout and scientifically understand the structural differences to jointly improve green and low-carbon development performance, while giving full play to the spatial spillover effect to form a joint force for improving green and low-carbon development performance.

Xiaoyi Zhang, Muhammad Usman, Ateeq ur Rehman Irshad et al.

While socioeconomic gradients in regional health inequalities are firmly established, the synergistic interactions between socioeconomic deprivation and climate vulnerability within convenient proximity and neighbourhood locations with health disparities remain poorly explored and thus require deep understanding within a regional context. Furthermore, disregarding the importance of spatial spillover effects and nonlinear effects of covariates on childhood stunting are inevitable in dealing with an enduring issue of regional health inequalities. The present study aims to investigate the spatial inequalities in childhood stunting at the district level in Pakistan and validate the importance of spatial lag in predicting childhood stunting. Furthermore, it examines the presence of any nonlinear relationships among the selected independent features with childhood stunting. The study utilized data related to socioeconomic features from MICS 2017–2018 and climatic data from Integrated Contextual Analysis. A multi-model approach was employed to address the research questions, which included Ordinary Least Squares Regression (OLS), various Spatial Models, Machine Learning Algorithms and Explainable Artificial Intelligence methods. Firstly, OLS was used to analyse and test the linear relationships among selected variables. Secondly, Spatial Durbin Error Model (SDEM) was used to detect and capture the impact of spatial spillover on childhood stunting. Third, XGBoost and Random Forest machine learning algorithms were employed to examine and validate the importance of the spatial lag component. Finally, EXAI methods such as SHapley were utilized to identify potential nonlinear relationships. The study found a clear pattern of spatial clustering and geographical disparities in childhood stunting, with multidimensional poverty, high climate vulnerability and early marriage worsening childhood stunting. In contrast, low climate vulnerability, high exposure to mass media and high women’s literacy were found to reduce childhood stunting. The use of machine learning algorithms, specifically XGBoost and Random Forest, highlighted the significant role played by the average value in the neighbourhood in predicting childhood stunting in nearby districts, confirming that the spatial spillover effect is not bounded by geographical boundaries. Furthermore, EXAI methods such as partial dependency plot reveal the existence of a nonlinear relationship between multidimensional poverty and childhood stunting. The study’s findings provide valuable insights into the spatial distribution of childhood stunting in Pakistan, emphasizing the importance of considering spatial effects in predicting childhood stunting. Individual and household-level factors such as exposure to mass media and women’s literacy have shown positive implications for childhood stunting. It further provides a justification for the usage of EXAI methods to draw better insights and propose customised intervention policies accordingly.

Gałka Elżbieta

The development of geotourism in the Holy Cross Mountains region has a long tradition based on the scientific and educational geological values of this area. In order to evaluate geotourism resources and their development in three representative areas of Świętokrzyskie voivodeship – the Holy Cross Mountains UNESCO Global Geopark (GGp), the central part of the Holy Cross Mountains and the Kamienna River Valley – a review of the literature and statistical data, and field studies of geosites and educational units were carried out. The Holy Cross Mountains UNESCO GGp is a first-rate geotourism region, which plays a leading role in geotourism and geoeducation, promoting geological values and infrastructure development. The central part of the Holy Cross Mountains and the Kamienna River Valley are classified as second-rate regions. The remaining areas of Świętokrzyskie voivodeship, with its unique geodiversity and biodiversity, are still waiting for their geological attractions to be discovered and shared with the broader public.

Mohammed Alzain

In Riemannian geometry, the Ricci flow is the analogue of heat diffusion; a deformation of the metric tensor driven by its Ricci curvature. As a step towards resolving the problem of time in quantum gravity, we attempt to merge the Ricci flow equation with the Hamilton-Jacobi equation for general relativity.

Yuliia Prasul, Natalia Bubyr, Yanina Melnyk et al.

Мета статті – обґрунтування методики геопросторово-картографічного аналізу альтернативної туристичної до­ступності регіонів України за окремими видами туризму та висвітлення результатів її апробації на практиці. Основний матеріал. У статті представлені результати оцінювання туристичних дестинацій (адміністративних об­ластей) за авторською методикою визначення альтернативної туристичної доступності. Альтернативна туристична доступність на цьому етапі дослідження передбачає оцінку територій як можливостей, що виключають одна одну, їх вибору для реалізації курортно-лікувального, культурно-розважального, пізнавального, релігійного, пішохідного видів туризму і є продовженням пошуків оптимальної моделі врахування факторів вибору дестинації з точки зору споживача туристичних послуг. Поєднання рейтингового підходу, методу суми місць, картографування для опрацю­вання базових і спеціальних показників територіальної, практичної, цінової, інформаційної доступності на прикладі Черкаської області як базової та її конкурентів серед областей України за названими вище видами туризму дозволи­ло отримати практичні рекомендації не тільки для самої Черкаської області, але і для інших областей, які становлять їй альтернативу. Геопросторово-картографічний аналіз визначений як найдоцільніший на всіх етапах дослідження: від вивчення території – до представлення результатів та прийняття адміністративних рішень. Висновки та подальші дослідження. За результатами дослідження виявили, що лідером є Київська область за культурно-розважальним, релігійним і пізнавальним видами туризму та Одеська область за курортно-лікувальним, пішохідним видами туризму завдяки розвиненій інфраструктурній складовій, гарній базовій територіальній доступ­ності та активному просуванню тематичних туристичних продуктів. Основними конкурентами для Черкаської облас­ті, яка значно програє лідерам за територіальним і практичним факторами альтернативної туристичної доступності, будуть такі області: за базовими показниками і щодо пізнавального туризму – Вінницька та Полтавська, щодо ку­рортно-лікувального – Вінницька і Миколаївська, щодо культурно-розважального – Полтавська і Херсонська, щодо релігійного – Вінницька та Хмельницька. Що ж до пішохідного спортивного і спортивно-оздоровчого, то тут спосте­рігається найсуворіша конкуренція. Перевагою Черкаської області є ціновий фактор. Серед областей, які займають найнижчі сходинки і часто не можуть конкурувати з більш сильними областями через цілу низку факторів недостат­нього рівня, виділяємо за різними видами туризму Тернопільську, Сумську, Хмельницьку, Житомирську області. На перспективу визначаємо напрямок адаптації запропонованої методики на рівні об’єднаних територіальних громад.

Wang Huaiyi, Li Zhongkui

[Objective] The research status of watershed ecological compensation was analyzed and mastered in order to provide a basis for improving the compensation system and promoting watershed ecological protection and high-quality development of river basins in China. [Methods] CiteSpace visualization software, Price's law, and the X index were used to analyze 876 studies collected by CNKI for author co-occurrence, high-frequency keywords, and research topic clustering. [Results] Domestic research on watershed ecological compensation mainly began in 2000, and the annual number of publications showed an upward trend. Research hotspots were highly coupled with national policies and watershed development, mainly including quantitative research on watershed ecological compensation standards, research on the behavior of watershed ecological compensation subjects from the perspective of game theory, and research on watershed ecological compensation mechanisms under the background of ecological protection. According to the evolution characteristics of research topics, three stages could be identified: preliminary exploration (before 2007), rapid development (2007—2017), and consolidation and improvement (from 2018 to 2021). During these time periods, research emphasis changed from theoretical analysis to quantitative analysis of compensation standards under the background of water resource governance. The objective of this research focused on the two major water systems of the Yangtze River basin and the Yellow River basin. Researches on the main stream and important tributaries were carried out alternately and gradually deepened. The researches formed multiple basic scientific research platforms, but there were few high-yield authors and little cross sectoral cooperation. [Conclusion] Over the past 20 years, research in the field of watershed ecological compensation in China has formed a certain theoretical system and research framework. The research topics and hot spots have distinctive characteristics, and the research methods have tended to be systematic and diversified. In the future, theory and application should be combined to explore the dynamic and market-oriented compensation mechanisms suitable for regional characteristics.

Vasily E. Tarasov

For the first time, a general fractional calculus of arbitrary order was proposed by Yuri Luchko in the works Mathematics 9(6) (2021) 594 and Symmetry 13(5) (2021) 755. In these works, the proposed approaches to formulate this calculus are based either on the power of one Sonine kernel, or the convolution of one Sonine kernel with the kernels of the integer-order integrals. To apply general fractional calculus, it is useful to have a wider range of operators, for example, by using the Laplace convolution of different types of kernels. In this paper, an extended formulation of the general fractional calculus of arbitrary order is proposed. Extension is achieved by using different types (subsets) of pairs of operator kernels in definitions general fractional integrals and derivatives. For this, the definition of the Luchko pair of kernels is somewhat broadened, which leads to the symmetry of the definition of the Luchko pair. The proposed set of kernel pairs are subsets of the Luchko set of kernel pairs. The fundamental theorems for the proposed general fractional derivatives and integrals are proved.

J. McGinn, C. Messenger, I. S. Heng et al.

We introduce the use of conditional generative adversarial networks forgeneralised gravitational wave burst generation in the time domain.Generativeadversarial networks are generative machine learning models that produce new databased on the features of the training data set. We condition the network on fiveclasses of time-series signals that are often used to characterise gravitational waveburst searches: sine-Gaussian, ringdown, white noise burst, Gaussian pulse and binaryblack hole merger. We show that the model can replicate the features of these standardsignal classes and, in addition, produce generalised burst signals through interpolationand class mixing. We also present an example application where a convolutional neuralnetwork classifier is trained on burst signals generated by our conditional generativeadversarial network. We show that a convolutional neural network classifier trainedonly on the standard five signal classes has a poorer detection efficiency than aconvolutional neural network classifier trained on a population of generalised burstsignals drawn from the combined signal class space.

Osvaldo L. Santos-Pereira, Everton M. C. Abreu, Marcelo B. Ribeiro

The Alcubierre warp drive metric is a spacetime construction where a massive particle located inside a spacetime distortion, called warp bubble, travels at velocities arbitrarily higher than the velocity of light. This theoretically constructed spacetime geometry is a consequence of general relativity where global superluminal velocities, also known as warp speeds, are possible, whereas local speeds are limited to subluminal ones as required by special relativity. In this work we analyze the solutions of the Einstein equations having charged dust energy-momentum tensor as source for warp velocities. The Einstein equations with the cosmological constant are written and all solutions having energy-momentum tensor components for electromagnetic fields generated by charged dust are presented, as well as the respective energy conditions. The results show an interplay between the energy conditions and the electromagnetic field such that in some cases the former can be satisfied by both positive and negative matter density. In other cases the dominant and null energy conditions are violated. A result connecting the electric energy density with the cosmological constant is also presented, as well as the effects of the electromagnetic field on the bubble dynamics.

Saeed Harati, Liliana Perez, Roberto Molowny-Horas

One of the complexities of social systems is the emergence of behavior norms that are costly for individuals. Study of such complexities is of interest in diverse fields ranging from marketing to sustainability. In this study we built a conceptual Agent-Based Model to simulate interactions between a group of agents and a governing agent, where the governing agent encourages other agents to perform, in exchange for recognition, an action that is beneficial for the governing agent but costly for the individual agents. We equipped the governing agent with six Temporal Difference Reinforcement Learning algorithms to find sequences of decisions that successfully encourage the group of agents to perform the desired action. Our results show that if the individual agents’ perceived cost of the action is low, then the desired action can become a trend in the society without the use of learning algorithms by the governing agent. If the perceived cost to individual agents is high, then the desired output may become rare in the space of all possible outcomes but can be found by appropriate algorithms. We found that Double Learning algorithms perform better than other algorithms we used. Through comparison with a baseline, we showed that our algorithms made a substantial difference in the rewards that can be obtained in the simulations.

Stephon Alexander, Gabriel Herczeg, Joao Magueijo

The Hartle-Hawking wave function is known to be the Fourier dual of the Chern-Simons or Kodama state reduced to mini-superspace, using an integration contour covering the whole real line. But since the Chern-Simons state is a general solution of the Hamiltonian constraint (with a given ordering), its Fourier dual should provide the general solution (i.e. beyond mini-superspace) of the Wheeler DeWitt equation representing the Hamiltonian constraint in the metric representation. We write down a formal expression for such a wave function, to be seen as the generalization beyond mini-superspace of the Hartle-Hawking wave function. Its explicit evaluation (or simplification) depends only on the symmetries of the problem, and we illustrate the procedure with anisotropic Bianchi models and with the Kantowski-Sachs model. A significant difference of this approach is that we may leave the torsion inside the wave functions when we set up the ansatz for the connection, rather than setting it to zero before quantization. This allows for quantum fluctuations in the torsion, with far reaching consequences.

E. Bontempo, E. Bontempo, M. C. Demirel et al.

The mapping of vegetation and Land Cover (LC) is important for research and for public policy planning but, in Brazil, although diverse maps exist there are few studies comparing them. The semiarid region of the Caatinga, in northeastern Brazil is an area long neglected by scientific research and its vegetation is diverse and relatively rich despite years of human occupation and very little preservation effort. In this study we make a comparison between the main maps made for the Caatinga from four different sources: IBGE (Brazilian Institute of Geography and Statistics), TCN (Third National Communication), ProBio (Project for Conservation and Sustainable Use of Biological Biodiversity) and MapBiomas. We also test these maps against well-known Land Cover maps from ESA and NASA: ESA’s GlobCover and Climate Change Initiative (CCI) Land Cover, and NASA’s MODIS MCD12Q1. This was done on a sample area where many of the Caatinga’s vegetation physiognomies can be found, using well-established Difference metrics and the new SPAtial EFficiency (SPAEF) algorithm as they present complementary viewpoints to test the correspondence of mapped classes as well as that of their spatial patterns. Our results show considerable disagreement between the maps tested and their class semantics, with IBGE’s and ProBio’s being the most similar among all national maps and MapBiomas’ the most closely related to global LC maps. The nature of the observed disagreement between these maps shows they diverge not only in the application of their classification systems, but also in their mapped spatial pattern, signaling the need for a better classification system and a better map of vegetation and land cover for the region.

Witalo Kassiano, Cláudio Assumpção, Ulisses Cunha et al.

The present study aimed to compare the intensity planned by the Personal Trainers (PTs) with that perceived by subjects in resistance training. Six male and female practicing resistance training (4 males and 2 females with mean age 33.0 ± 6.16 years, 1.3 ± 0.55 years training with follow-up) and two PTs participated in the study (average 32.0 ± 4.0 years, postgraduates, with a five -year or more experience). The comparison between the intensity planned by the PT and the intensity experienced by the subjects was determined by the Rating of Perceived Exertion (RPE). Previously, at the beginning of each training, the PT should respond individually to the RPE estimated for each student in that training session. At the end of each session, 30 minutes after its completion, this same scale was answered by the subjects. To compare the intensity of the sessions perceived by the subjects and that planned by the PTs, we used descriptive statistics, standardized mean differences and their confidence intervals. Results have showed that subjects reported substantially higher intensities (small effect size) when compared to PTs. It has been concluded that the intensity experienced by the subjects was substantially higher than that planned by the PTs.

Jorge Luis Cué García, Yajaira Alexandra Cuasque Peñafiel, Hugo Vinicio Vallejos Álvarez et al.

The management of forest seeds in Ecuador, in relation to their storage, is still insufficient, in particular the Cinchona pubescens Vahl. The objective was to determine the quality of the seeds and the best methods of seed storage of C. pubescens, using different times, containers and conditions. Seed collection was in Intag, Imbabura. The factors under study were: storage time, types of packaging and storage conditions. The quality of the seeds was determined at the time of harvest and in each treatment. Purity reached 76.5 %, the weight of 1,000 seeds was 0.31 g and the humidity content was 14 %. In the first storage trial, no germination was observed in any treatment from the first month. In the second trial, the best storage method was transparent cover stored in refrigeration for one week, which showed 9.25 % germination power. Cinchona pubescens seeds lose their viability quickly, which becomes null after one month of storage.

Mădălin-Sebastian LUNG

Through this article we wanted to conduct a research on the demographic component in the Romanian Carpathians by dividing the Carpathian Oicumenical into the Internal Carpathian Oicumena and External Carpathian Oicumena. We also wanted to identify cycles of demographic evolution and involutivity in the Romanian Carpathian space, and in parallel to identify several causes of different orgini that underwent the continuity and the demographic cyclical. The studied Period is 1930-2011, with statistical data taken from four censused: 1930, 1977, 1992 and 2011. Their processing was done using the Microsoft Excel 2013 program, calculating demographic increases. Then, the resulting increases served in the implementation of the database, and their processing was done through geographic information systems (ArcGis 10.3), making maps representative of the intended purpose. In 1930, the urban environment was little represented in the Romanian Carpathians, but after the establishment of socialism, the number of cities increased greatly. Instead, the rural environment began to be gradually disintegrated by the communist regime, with the population having to migrate to urban centres. On the whole, the population of the Romanian Carpathians rose from 1930 to 1977 and 1992, with the beginning of the demographic decline, with the establishment of capitalism. In the period 1977-1992, the Carpathian population increased by 5%, and from 1992 to 2011, decreased by 16%.

Jarosław Błasiok, Venkatesan Guruswami, Preetum Nakkiran et al.

Arikan's exciting discovery of polar codes has provided an altogether new way to efficiently achieve Shannon capacity. Given a (constant-sized) invertible matrix $M$, a family of polar codes can be associated with this matrix and its ability to approach capacity follows from the {\em polarization} of an associated $[0,1]$-bounded martingale, namely its convergence in the limit to either $0$ or $1$. Arikan showed polarization of the martingale associated with the matrix $G_2 = \left(\begin{matrix} 1& 0 1& 1\end{matrix}\right)$ to get capacity achieving codes. His analysis was later extended to all matrices $M$ that satisfy an obvious necessary condition for polarization. While Arikan's theorem does not guarantee that the codes achieve capacity at small blocklengths, it turns out that a "strong" analysis of the polarization of the underlying martingale would lead to such constructions. Indeed for the martingale associated with $G_2$ such a strong polarization was shown in two independent works ([Guruswami and Xia, IEEE IT '15] and [Hassani et al., IEEE IT '14]), resolving a major theoretical challenge of the efficient attainment of Shannon capacity. In this work we extend the result above to cover martingales associated with all matrices that satisfy the necessary condition for (weak) polarization. In addition to being vastly more general, our proofs of strong polarization are also simpler and modular. Specifically, our result shows strong polarization over all prime fields and leads to efficient capacity-achieving codes for arbitrary symmetric memoryless channels. We show how to use our analyses to achieve exponentially small error probabilities at lengths inverse polynomial in the gap to capacity. Indeed we show that we can essentially match any error probability with lengths that are only inverse polynomial in the gap to capacity.