Hasil untuk "Geography (General)"

Yan-bo Zeng, Jian-dong Zhang, Yi-Ming Hu et al.

One of the main targets for space-borne gravitational wave detectors is the detection of Extreme Mass Ratio Inspirals (EMRIs). The data analysis of EMRIs requires waveform models that are both accurate and fast. The major challenge for the fast generation of such waveforms is the generation of the Teukolsky amplitudes for generic (eccentric and inclined) Kerr orbits. The requirement for the modeling of $\sim10^5$ harmonic modes across a four-dimensional parameter space makes traditional approaches, including direct computation or dense interpolation, computationally prohibitive. To overcome this issue, we introduce a convolutional encoder-decoder architecture for a fast and end-to-end global fitting of the Teukolsky amplitudes. We also adopt a transfer learning strategy to reduce the size of the training dataset, and the model is trained gradually from the simplest Schwarzschild circular orbits to generic Kerr orbits step by step. Within this framework, we obtain a surrogate model based on a semi-analytical Post-Newtonian dataset, and the full harmonic amplitudes can be generated within milliseconds, while the median mode-distribution error for generic orbits is approximately $\sim10^{-3}$. This result indicates that the framework is viable for constructing efficient waveform models for EMRIs.

Huma Ali, Muhammad Rafiq, Muhammad Manzoor et al.

Abstract Background The western Himalayan forest ecosystem faces escalating pressures from climate change and anthropogenic activities, demanding improved conservation strategies. Effective management requires understanding the seasonal fluctuations in vegetation, soil properties and microbial communities, but they remain poorly characterized across high altitude forests. We assessed these variables in 10 forest sites during the winter of 2023 and summer of 2024, analysing vegetation diversity, soil parameters, and microbial metagenomics. Results We found pronounced seasonal shifts in plant and microbial diversities, and in soil properties. Plant species richness, and Shannon and Simpson diversity indices were higher (p < 0.001) in summer than in winter while the community maturity index was higher (p < 0.02) in winter than in summer. Soil properties exhibited clear seasonal patterns: pH, available phosphorus (AP), microbial biomass carbon (MBC) and cation exchange capacity (CEC) were higher (p < 0.05) in summer, whereas soil moisture (SM) and soil organic carbon (SOC) were higher (p < 0.05) in winter. Microbial alpha diversity indices (Shannon, Chao, and Sobs) were elevated (p < 0.05) in summer, while the Simpson index was elevated in winter, indicating a shift in community dominance. Beta diversity analyses revealed a significant seasonal shift in overall metabolic potential (KEGG orthologs; ANOSIM R = 0.222, p = 0.016), but not in general protein functions (COG), carbohydrate-active enzymes (CAZy), or taxonomic composition (RefSeq). Therefore, despite taxonomic turnover, core metabolic functions were maintained, indicating strong functional redundancy. Structural equation models (SEM) confirmed distinct seasonal dynamics, revealing stronger plant-soil-microbe interactions and a greater proportion of variance explained by the model in summer (R2=0.64–0.72 for key paths) than in winter (R2=0.52–0.63). Conclusions The findings demonstrate that the western Himalayan ecosystem undergoes a fundamental seasonal reorganization. Summer is characterized by increased biodiversity, distinct soil conditions, and more dynamic microbial-ecosystem interactions, while winter exhibits greater community maturity and functional stability. The resilience of core ecosystem processes is underpinned by microbial functional redundancy, which ensures metabolic continuity despite taxonomic shifts. We recommend that forest management strategies account for these seasonal dynamics and focus on preserving the conditions that support this critical functional redundancy.

Wenli Guo, Xiaoli Lei, Chen Liang et al.

Mayorella marianaensis (Amoebozoa: Discosea) was the only Mayorella species isolated from deep sea (over 3000 m-depth). We firstly present a transcriptomic analysis of the non-model amoeba species collected from the Mariana Trench area. Illumina sequencing platform was used to generate data which including raw data, cleaned reads, de novo assembly, and functional annotation. After assembly, the final transcriptome consists of 57,459,544 transcripts with a mean length of 1646 and N50 length of 1170. The transcriptome has a completeness of 67.4 % as assessed by BUSCO. Functional annotation pathways related to signal transduction, transport and catabolism, and translation are the most annotated in the transcriptome.

Onay Hatice, Kurtul Irmak, Kaya Cüneyt et al.

This study analyzed the length–weight relations and condition factors of 13 species belonging to three highly endemic genera: Oxynoemacheilus (6), Seminemacheilus (2) and Cobitis (5). Fish were sampled in several streams and lakes using a backpack electroshocker. Analyses were based on a total number of individuals, which was n = 304. A linear regression model was applied to determine the relationship between fish length and weight. The coefficient of determination (R2) ranged from 0.950 to 0.980 for all populations (p < 0.05). Allometric coefficient ‘b’ values ranged from 2.498 to 3.201 for Oxynoemacheilus, from 2.970 to 2.127 for Seminemacheilus, and from 2.111 to 3.076 for Cobitis populations. Fulton’s condition factor for Oxynoemacheilus, Seminemacheilus and Cobitis ranged from 0.391 to 3.080. This study addresses gaps in LWR and CF information for a number of ecologically important freshwater fish species. It is expected that the results of this research provide baseline data for further fisheries management studies and may support conservation studies of related species.

M. Tibayrenc, F. Kjellberg, F. Ayala

José Roberto Mantovani, Leandro Reginaldo Maximino Lelis

Propõe-se uma metodologia que utiliza conceitos matemáticos da teoria de formação de clusters, o K-means, para obter de forma automática os clusters dos valores do NDVI. As implementações do método K-means existentes em softwares específicos exige a predefinição no número de clusters, sendo a contribuição desta metodologia a determinação do número de clusters automaticamente, sem a necessidade da interferência do tomador de decisões que, pode variar de acordo com o tempo e o espaço de uma imagem para outra, bem como de um sensor para o outro. Foram selecionados diferentes sensores para generalizar essa classificação do índice: Thematic Mapper (TM) a bordo do satélite Landsat-5; Operational Terra Imager (OLI) a bordo do satélite Landsat-8; MultiSpectral Instrument (MSI) a bordo do satélite Sentinel, nível-2A. O mapeamento e a validação do algoritmo são efetuados na região nordeste do estado de Mato Grosso do Sul, a qual, apresenta ao longo de 37 anos (1984- 2021) alterações em sua cobertura vegetal. Os resultados para os três períodos, fornecidos pelo algoritmo distinguiu melhor o comportamento espectral dos pixels referentes às classes de água, solo exposto e áreas urbanas; já o JENKS generalizou essas classes, por outro lado, distinguiu com melhor precisão vegetação de baixo porte, vegetação natural e florestas plantadas.

Carolina Paula Ricci, Mariana Lamego

Este dossier, como todo trabajo colectivo, tiene una historia de encuentros. Nos conocimos a raíz de la organización del XVIII Encuentro de Geografías de América Latina (EGAL) y VIII Congreso Nacional de Geografía de Universidades Públicas de la República Argentina realizado en Córdoba en el año 2021. Algunxs de quienes participamos en la comisión académica comenzamos a plantear la necesidad de pensar determinadas mesas temáticas que mostraran “otros” campos del saber o, mejor dicho, “otras formas de pensar y abordar” diversas tradiciones disciplinares. Allí surgió la idea de armar, dentro del eje teórico-metodológico, una mesa orientada al abordaje de la (r)existencia de “otras trayectorias geográficas” que mostraran diversos aspectos de la historia de la Geografía –sus sujetxs, saberes y contextos– por fuera del dogma disciplinar. En conversaciones con la Dra. Perla Zusman sugirió un trabajo articulado entre nosotras junto con el Dr. Paulo Albuquerque de Bomfin y la Esp. Rita Maldonado. Esa mesa –denominada “Otras trayectorias geográficas: historias y aportes conceptuales de las geografías silenciadas”– reunió diversos trabajos que desafiaron las formas tradicionales de abordar las temáticas, problemas e historias de las geografías y se constituyó el puntapié para el comienzo de un trabajo de cooperación entre ambas.

Jonathan Rotich, Elıjah Rıntaugu, Edna Thangu

General practitioners are regarded as athletic support personnel as they are involved in delivering supportive services such as treating athletes participating in or preparing for sports competitions. General practitioners play a vital role in influencing athletes to fulfill their mandate to adhere to clean sports and therefore, their additional knowledge in sports is required to comprehensively address their health needs without affecting the integrity of rules that govern fair play. General practitioners require sufficient doping knowledge to provide athletes with health needs consistent with anti-doping regulations. In Kenya, no studies have investigated or reported the doping knowledge, attitude or experience of General Practitioners, thus leaving a knowledge gap on their ability to treat competitive athletes harmonious with WADA requirements. Therefore, the study sought to unearth General Practitioners' doping knowledge, attitude, and experience in Kenya. The study's findings have implications on doping knowledge, attitude, and experience of Kenya General Practitioners’ essential to inform the current status of the concept. A cross-sectional analytical study design was selected because of its robustness in describing general practitioners' current doping knowledge, attitude, and experiences. Data was collected using a self-reported and validated questionnaire where 250 General practitioners completed the survey. Findings revealed that Kenyan general practitioners are well aware of doping regulatory agencies of WADA and ADAK. The findings demonstrated that General Practitioners had an average doping knowledge (47.77 ± 14.03) punctuated with limited knowledge of prohibited substances, methods, and substances in certain sports. Work experience significantly influenced General Practitioners knowledge, F (4,245) = 10.852, p lt; .001. General Practitioners had a negative doping attitude of 45.23 ± 13.64. As many as 22% (55) General Practitioners received doping requests for the last 12 months, where 35.7% (89) of requests are about drugs to aid recovery. Anabolic steroids, corticosteroids, and peptide hormones were among the most sought-after PEDs. General Practitioners in Kenya have inadequate doping knowledge, which could limit their efficacy in treating professional athletes in line with WADA guidelines. Additional anti-doping training could benefit them address this limitation. Although General Practitioners demonstrated a negative attitude, expanding their involvement through active participation in doping seminars, and programs can enhance their understanding of the doping concept necessary to develop and maintain a strong negative attitude.

L. A. Rvachev, I. Longini

J. Jeschke, D. Strayer

N. Thrift, J. Dewsbury

B. Robertson, R. Jansen, B. Khanna et al.

Karan Fernandes, Susovan Maity, Tapas K. Das

As of now, all analogue gravity models available in the literature deal with the emergence of an acoustic geometry through linear perturbations of transonic fluids only. It has never been investigated whether the analogue gravity phenomena is solely a consequence of linear perturbations, or rather a generic property of arbitrary perturbations of inhomogeneous, inviscid and irrotational fluids. In the present work, for the first time in the literature, we demonstrate that acoustic spacetimes may be formed through higher order non-linear perturbations, and thus establish that analogue gravity phenomena is rather more general than what was thought before. We consider spherically accreting astrophysical systems as a natural classical analogue gravity model, and develop a formalism to investigate non-linear perturbations of such accretion flows to arbitrary order. Our iterative approach involves a coupled set of equations for the mass accretion rate and the density of the fluid. In particular, we demonstrate that the wave equation for the mass accretion rate involves an acoustic metric which can be perturbatively constructed to all orders. We numerically solve the coupled equations about the leading transonic Bondi flow solution. This analysis uses boundary conditions set to the original unperturbed values, with the time dependence of the mass accretion rate perturbation taken to be exponentially damped. The perturbed solutions indicate that second order and higher perturbations of the metric generically cause the original acoustic horizon to oscillate and change in size. We explain this phenomenon in detail and its implications on non-linear perturbations of accretion flows in general.

B. V. Ivanov

It is shown that the expressions for the tangential pressure, the anisotropy factor and the radial pressure in the Einstein - Maxwell equations may serve as generating functions for charged stellar models. The latter can incorporate an equation of state when the expression for the energy density is also used. Other generating functions are based on the condition for the existence of conformal motion (conformal flatness in particular) and the Karmarkar condition for embedding class one metrics, which do not depend on charge. In all these cases the equations are linear first order differential equations for one of the metric components and Riccati equations for the other. The latter may be always transformed into second order homogenous linear differential equations. These conclusions are illustrated by numerous particular examples from the study of charged stellar models.

R. V. Ilin, S. A. Paston

The current paper is devoted to the investigation of the general form of the energy-momentum pseudotensor (pEMT) and the corresponding superpotential for the wide class of theories. The only requirement for such a theory is the general covariance of the action without any restrictions on the order of derivatives of the independent variables in it or their transformation laws. As a result of the generalized Noether procedure, we obtain a recurrent chain of the equations, which allows one to express canonical pEMT as a divergence of the superpotential. The explicit expression for this superpotential is also given. We discuss the structure of the obtained expressions and the conditions for the derived pEMT conservation laws to be satisfied independently (fully or partially) of the equations of motion. Deformations of the superpotential form for theories with a change of the independent variables in the action are also considered. We apply these results to some interesting particular cases: General Relativity and its modifications, particularly mimetic gravity and Regge-Teitelboim embedding gravity.

Luciano Combi, Gustavo E. Romero

We analyze the necessary conditions for a body to remain rigid in an expanding cosmological Universe. First, we establish the main theorems and definitions for having a rigid body in a general spacetime as well as the new concept of quasilocal rigidity. We apply the obtained results to a homogeneous universe exploring the differences with flat spacetime. We discuss how the concept of rigid body helps to understand the expansion of space in cosmology. Finally, using a rigid system as a reference frame, we calculate the gravitational energy, and we compare it with previous results in the literature.

Judson Jorge da Silva, Cláudio Ubiratan Gonçalves

Este trabalho analisa como as migrações sazonais de quilombolas da região do semiárido piauiense para o trabalho acessório têm sido utilizadas como estratégia de resistência para a permanência no território, a partir do exemplo dos moradores da comunidade Lagoa das Emas, pertencente ao território de quilombo Lagoas. Apresenta uma discussão a respeito da pluralidade de constituição dos territórios quilombolas, mostrando que não se trata de uma questão homogênea, tampouco linearmente ligada a redutos de escravos fugitivos no passado. Aponta que as migrações são resultado de um processo de desenvolvimento territorial desigual do trabalho, mas que, estrategicamente, são realizadas como forma de manutenção do grupo familiar no quilombo, configurando-se como uma espécie de resistência onde, dialeticamente, partir se configura como possibilidade de permanecer.

Izza Indah Afkarina Kunny, Sarwanto Moersidik Setyo, Warno Utomo Suyud

The Citarum River is one of the most polluted rivers in the world because of the inadequate waste management system and community ignorance. Plastic is one of the contaminants in the Citarum watershed. In general, plastics less than 5 mm in size are defined as microplastics. Microplastics are persistent and harm the environment. This article aims to determine the potential for pollution and distribution of microplastics in freshwater systems, especially in the Citarum watershed area. Using a combination of literature study methods with Geographical Information Systems (GIS) analysis, this article explains that microplastic contamination has occurred along the Citarum watershed from upstream to downstream, found in water and sediment and fish samples. Facilitated by their small size and high stability in the environment, microplastics can move from the aquatic environment into the food chain and cause longterm damage. This case causes a severe threat to the quality of freshwater in the Citarum watershed. Therefore, this article can be used as a reference for managing pollution in the Citarum watershed area.

I. Wistuba, A. Gazdar