Ciudad Universitaria (University City), Mexico, is the main campus of the National Autonomous University of Mexico (UNAM), located in Coyoacán borough in the southern part of Mexico City. Designed by architects Mario Pani and Enrique del Moral, it encloses the Olympic Stadium, about 40 faculties and institutes, the Cultural Center, an ecological reserve, the Central Library, and a few museums. It was built during the 1950s on an ancient solidified lava bed in Coyoacán called "El Pedregal" to replace the scattered buildings in downtown Mexico City where classes were given. It was completed in 1954 at a cost of approximately $25 million. At the time of its completion it was the largest single construction project in Mexico since the Aztecs. It was declared a World Heritage Site by UNESCO in 2007.Although the University has other buildings in Mexico City (mostly for undergraduate studies and cultural purposes), in other Mexican states and in other countries (such as Canada and the United States), Ciudad Universitaria, known simply as "C.U.", is the prime symbol of the University.U.U.U.
The shrub oaks of Quercus section Quercus have been poorly studied in Mexico. Within these shrub oaks, Quercus microphylla and morphologically similar taxa (i.e., the Q. microphylla complex) still exhibit a great deal of taxonomic uncertainty related to species identity and delimitation. Quercus striatula is a name in this complex to which morphologically divergent population groups have been associated. Applying an integrative taxonomy approach, we used morphology and geometric morphometrics, genetic analyses with nuclear microsatellite markers, and ecological niche models, to establish the boundaries between morphologically different populations within Q. striatula, in conjunction with Quercus cordifolia, a morphologically close species. Our results support a clear separation of three taxa, which allowed us to propose Quercus oyamae as a new species for science, which corresponds to plants from the Mexican Plateau previously considered as Q. striatula. The new species is described and illustrated and a key for its identification is included.
Freshwater decapod crustaceans in Mexico's South Pacific rivers play a key role in biomass transport, but face constant threats from fishing and pollution. To analyse the temporal and spatial distribution of the decapods in the Manialtepec River, Oaxaca, their prevalence was studied at stations located in the lower, middle, and upper portions of the river, with the station farthest from the coast located 24 km upstream. At each station, three sites were established; collections at each site were conducted for 20 min using spoon nets with a 0.5 mm mesh opening. In four samplings taken between February 2024 and February 2025, 560 specimens from three families, four genera, and nine species of decapods were recorded. The best-represented family was Palaemonidae, with one genus and five species, followed by the Atyidae, with two genera and three species, and one specimen of Pseudothelphusidae. The most abundant species was Macrobrachium tenellum, followed by M. hobbsi, Atya margaritacea and A. cf. ortmannioides. The diversity index increases towards the middle of the river during both the rainy and dry seasons. Principal coordinate analysis (PCoA) revealed a clear species arrangement in the lower, middle and upper portions of the river. Permutational Multivariate Analysis of Variance (PERMANOVA) analysis concluded that these differences were statistically significant, identifying three assemblages: (1) M. tenellum; (2) P. glabra, M. hobbsi, M. digueti, M. occidentale, A. margaritacea; and (3) Pseudothelphusa sp., M. americanum, A.cf. ortmannioides. The study demonstrates remarkable decapod diversity in the Manialtepec River, with distinct spatial assemblages and seasonal flexibility that highlight the ecological richness and importance of conserving these freshwater communities.
Abstract We provide a detailed derivation of the Schwarzian modes in the full geometry of the Bañados-Teitelboim-Zanelli (BTZ) black hole at finite temperature, establishing the precise conditions under which they emerge from the general solution, thereby clarifying the absence of rotational modes in the full geometry. In addition, we demonstrate that the same modes can be recovered through a purely geometric Kerr-Schild construction. This equivalent approach offers a new geometric understanding of the Schwarzian sector and highlights the correspondence between perturbative and pure geometric approaches, additionally it provides a connection with double copy.
We study the one-loop correction to the entropy of near-extremal black holes in three-dimensional massive gravity at the special point where the theory exhibits a unique maximally symmetric vacuum and non-constant curvature hairy black holes can achieve extremality even in the static case. Focusing on the near-horizon AdS_2× S^1 geometry, we evaluate the contribution of boundary graviton modes that become exact zero modes in the extremal limit. We show that the resulting one-loop partition function generates logarithmic corrections to the semiclassical entropy, providing a new extension to higher-curvature gravity of what has been recently obtained for near-extremal black holes in General Relativity.
