Hasil untuk "Geography (General)"

L. Binford

D. Prudham, J. G. Evans

R. Barry

M. Hartevelt, J. Bavinck, A. Kootte et al.

G. Ebers, A. Sadovnick, N. Risch

Laban Kayitete, Elie Sinayitutse, Matthew Dennis

The Hooded Vulture (Necrosyrtes monachus) plays a vital role in environmental cleaning and disease control. However, its population is rapidly declining across its range, especially in East Africa. Despite conservation efforts invested in its protection, its spatial distribution in East Africa remains understudied. Utilising ensemble Species Distribution Models, this study leverages the response of N. monachus to bioclimatic factors, elevation, and land cover to predict the species' current distribution across Kenya, Rwanda, Tanzania, and Uganda, and assess potential climate change impacts. Findings reveal that only 11.813 % of the study area represents suitable habitat for N. monachus, with 35.954 % of this falling within protected areas. The Hooded Vulture exhibited strong dependence on climatic conditions, with variables of large influence to its distribution being isothermality, annual mean temperature, precipitation seasonality, elevation, and annual precipitation, while the urban land exhibited moderate influence. Climate change projections indicate regional habitat stability, but varying spatial and climatic pathway-based trajectories, with habitat expansions under sustainable development pathways (SSP126) and mixed outcomes under fossil-fuelled scenarios (SSP585), particularly affecting Kenya with consistent declines, while Tanzania, Uganda, and Rwanda showed expansions. The proportion of suitable habitat within protected areas remained stable across scenarios, though substantial national disparities persist. This research underscores the role of modelling in informed conservation and urgency in transboundary conservation strategies extending beyond currently protected areas and provides critical insights for adaptive conservation planning to safeguard the Hooded Vulture's future in East Africa.

Yupeng LI, Yaning CHEN, Fei WANG et al.

Tajikistan, a mountainous country and a vital water tower for Central Asia, is becoming increasingly vulnerable to snow drought under climate change, threatening its snow- and glacier-fed streamflow. Yet, the impacts of snow drought on the regional hydrology remain insufficiently understood. In this study, we integrated multisource data, including the Fifth Generation European Centre for Medium-Range Weather Forecasts Atmospheric Reanalysis for Land Applications (ERA5-Land) data and hydrological station data, to systematically assess the snow drought patterns and their impacts on streamflow during 1950–2023. We identified snow drought events based on precipitation and snow fraction anomalies relative to climatological means and classified them into warm snow drought, dry snow drought, and warm&dry snow drought. The results revealed that snow drought was a recurrent phenomenon, occurring in 51.70% of the years during the study period, with warm&dry snow drought accounting for 21.90% of the total events. Both the frequency and severity exhibited pronounced spatial variability, largely governed by the elevation and snowfall fraction. Specifically, the frequency of warm snow drought was negatively correlated with the snowfall fraction, decreasing on average by 0.20 per unit increase in snowfall fraction, whereas the frequency of dry snow drought was positively correlated, increasing by 0.07 per unit increase. The streamflow analysis results demonstrated that snow drought typically reduced the warm-season discharge by 5.00%–18.00% in certain rivers, thereby exacerbating the water stress during the dry season. The results of this study advance our understanding by explicitly linking the types of snow drought to hydrological responses in Central Asia’s high mountains, providing a scientific basis for climate adaptation and sustainable water resource management in Tajikistan.

Martin W. Lewis, Karen Wigen

Hodek M. García, Marcelo Salgado

By implementing a full non-linear treatment of $f(R)$ gravity in static and spherically symmetric spacetimes, we analyze two scenarios. The first one within the context of the solar-system tests where we try to recover the chameleon effects without any approximations in the equations (e.g. linearization) from $f(R)$ models that are compatible with cosmology. The second scenario deals with a quadratic $f(R)$ model that is tested in neutron stars. This scenario, which is associated with strong gravity, is completely independent from the first one, but exploits the fact that the equations and formalism are basically the same in both applications. The difference between the two goals lies mainly in the values of the constants involved in the specific $f(R)$ models and the equation of state (EOS) of the central object (Sun or neutron star), but the numerical techniques and the general form of the field equations remain valid in both situations. For the neutron star problem we employ for the first time and in the context of $f(R)$ gravity a multiple algebraic polytropic EOS that mimics accurately realistic EOS in several density ranges. By doing so we avoid the numerical interpolation needed when a realistic EOS is given in tabulated form. Furthermore, we compare our results with the latest data, which includes the most massive neutron star known to date of about $2.35 M_\odot$ from PSRJ0952-0607.

Moritz Reintjes, Ruochen Xia

We give the first general construction of solutions of the static spherically symmetric Einstein-Euler equations, the Tolman-Oppenheimer-Volkoff (TOV-)equation, with prescribed density functions allowed to be discontinuous and non-uniform; these solutions describe stellar phase transitions in General Relativity. Boundedness of the resulting pressure functions solving the TOV-equations, from the boundary down to the stellar center, is obtained by identifying a novel condition on the prescribed density, in generalization of the classical Buchdahl limit. Moreover, we introduce a new necessary condition for the existence of such bounded pressure functions, which in the special case of a uniform density state reduces to the classical Buchdahl limit on the stellar mass-radius relationship. We present various examples to study the stellar mass-radius relationships resulting from our new conditions.

Yepes Jairo E., Hoyos Laureano R., Velosa Claudia L. et al.

A thorough experimental program has been undertaken to assess the suction-controlled peak and residual shear strength responses of statically compacted, moderate plasticity clayey soil over a relatively wide range of suction states. The experimental program was accomplished via a servo/suction-controlled ring shear apparatus suitable for testing unsaturated soils under large deformations via the axis-translation technique. Results further substantiate the crucial role that has been observed to be played by the imposed matric suction on residual shear strength behaviour of compacted clayey soils. For the range of net normal stresses (0-200 kPa) and matric suction states (0-300 kPa) investigated, the increase in both peak and residual shear strength, with increasing matric suction, was found to be markedly nonlinear. Furthermore, a readily distinct correspondence was observed between the nonlinear nature of either peak or residual shear strength envelopes, with respect to increasing matric suction, and the very nature of the soil-water retention curve of the test soil. Results, in general, confirm that a conceptual residual shear strength framework for unsaturated soils, analogous to that postulated for peak shear strength, can be formulated with reasonable reliability.

Gökhan Topçu, Pınar Yürür, Arda Özkan

The seas have been the scene of wars between major naval powers at different period of history. One of the most important results of these wars was the birth of maritime law. Over time, the demands of states regarding the use of the seas increased. As a result of such developments, the UNCLOS emerged in 1982 as a result of the conferences on the law of the sea. As a result of the expansion of the areas of activity in the seas and the increasing energy needs in the world, the importance of the Eastern Mediterranean, as in other strategic seas, has started to increase gradually. This situation has made the issue of the delimitation on the maritime areas in the region important and in this study, the relations between two important states of the region, Turkey and Egypt, are discussed in the context of maritime jurisdiction areas. The aim of the study is to provide an informative perspective and contribute to the determination of the suitable road map to be followed pro-actively in order to achieve results based on the equitable principles within the framework of the rights and interests of the two states. In the study, in which the content analysis method is used, it is predicted that the period in which political relationsbetween the states are re-established and open-door diplomacy is carried out will continue in a positive direction.

Dede Yopi Akbar, Maman Suherman

Bulutangkis merupakan cabang olahraga paling populer dan berprestasi di Indonesia yang secara konsisten menyumbangkan medali di kancah internasional serta menjadi sumber kebanggaan nasional. Prestasi ini tidak lepas dari peran klub-klub bulutangkis yang berfungsi sebagai garda terdepan dalam pembinaan dan pengembangan atlet sejak usia dini. Penelitian ini bertujuan untuk mendeskripsikan upaya Diklat Bulutangkis Lembang Badminton Club (LBC) dalam meningkatkan prestasi atlet di Kabupaten Bandung Barat. Penelitian menggunakan pendekatan deskriptif kualitatif dengan teknik pengumpulan data berupa observasi, wawancara mendalam, dan dokumentasi. Subjek penelitian meliputi pelatih, pengurus diklat, dan beberapa atlet binaan LBC. Data dianalisis menggunakan model Miles dan Huberman melalui reduksi data, penyajian data, dan penarikan kesimpulan. Validitas data diperkuat dengan triangulasi sumber dan teknik untuk memastikan keabsahan informasi. Hasil penelitian menunjukkan bahwa LBC menerapkan berbagai strategi pembinaan yang meliputi program latihan terstruktur dengan frekuensi 3-4 kali per minggu, pembinaan mental dan fisik yang komprehensif, pendampingan intensif oleh pelatih berkompeten dengan latar belakang akademik dan pengalaman sebagai atlet, serta penyediaan sarana dan prasarana yang memadai. Strategi pembinaan juga mencakup partisipasi aktif dalam kejuaraan di berbagai tingkat dan dukungan orang tua yang konsisten. Upaya-upaya tersebut terbukti efektif dalam mendukung peningkatan prestasi atlet, baik pada tingkat kejuaraan daerah maupun provinsi, dengan beberapa atlet berhasil meraih medali dan mengikuti seleksi tingkat nasional.

James R. Markusen, Keith E. Maskus

D. Coleman, Y. Georgiadou, J. Labonte

Pardeep Sharma, Sandeep K. Sood, Sumeet Kaur

Carmen Gómez-Fayrén, Patrick Meessen, Tomás Ortín

Motivated by the current research of generalized symmetries and the construction of conserved charges in pure Einstein gravity linearized over Minkowski spacetime in Cartesian coordinates, we investigate, from a purely classical point of view, the construction of these charges in a coordinate- and frame-independent language in order to generalize them further. We show that all the charges constructed in that context are associated to the conformal Killing-Yano 2-forms of Minkowski spacetime. Furthermore, we prove that those associated to closed conformal Killing-Yano 2-forms are identical to the charges constructed by Kastor and Traschen for their dual Killing-Yano (d-2)-forms. We discuss the number of independent and non-trivial gravitational charges that can be constructed in this way.

Khaoula Saadaoui

D. Rosauer, S. Laffan, M. Crisp et al.

J. Coyne