Numerical simulation of sloshing in liquid storing tanks by an arbitrary Lagrangian-Eulerian strategy

La agitación de fluidos contenidos en tanques de almacenamiento con superficie libre es numéricamente simulada mediante una formulación lagrangiana-euleriana arbitraria. El fluido es considerado viscoso y de comportamiento newtoniano, mientras que el flujo se asume laminar e incompresible. Se emplea un código computacional particionado y distribuido, que resuelve tres instancias en cada paso de tiempo: (i) la determinación del estado en el fluido, representado por las ecuaciones de Navier–Stokes; (ii) el desplazamiento de la superficie libre; y (iii) la actualización de la posición de los nodos interiores de la malla de elementos finitos, que es deformada como consecuencia del desplazamiento de la superficie libre. El propósito del trabajo es verificar la aplicabilidad del método en problemas de agitación de solución conocida, así como también resolver algunos ejemplos prácticos. Los ejemplos numéricos incluyen la validación con soluciones analíticas, en las cuales el período de la onda y la tasa de amortiguamiento viscoso son bien capturadas, comparaciones con soluciones de referencia tomadas de otros autores y un caso de agitación inducida por acción sísmica.Sloshing of fluids with a free surface contained in liquid storage tanks is numerically simulated by an arbitrary Lagrangian-Eulerian formulation. The fluid is considered viscous and Newtonian, while the flow is assumed laminar and incompressible. A partitioned and distributed computational code is employed, which solves three instances each time step: (i) the determination of the fluid state, given by the Navier–Stokes equations; (ii) the displacement of the free surface; and (iii) the update of the position of the internal nodes of the mesh, that is deformed as a consequence of the free surface displacement. The purpose of the work is verifying the applicability of the method to sloshing problems with known solutions, as well as the resolution of some practical examples. Numerical examples include validations against analytical solutions, where the wave period and damping rate are well captured, comparisons with reference results from other authors and a sample of sloshing induced by seismic actions.Peer Reviewe

Life Cycle of the Parasite Profilicollis chasmagnathi (Acanthocephala) on the Patagonian Coast of Argentina Based on Morphological and Molecular Data

This study verifies the identity of adult specimens of the parasite Profilicollis chasmagnathi (Acanthocephala, Polymorphidae) recovered from kelp gulls Larus dominicanus (Aves, Laridae), and cystacanths found in crabs Cyrtograpsus altimanus (Crustacea, Decapoda) from the southwestern Atlantic coast. The life cycle of this parasite is elucidated in the intertidal zone of Patagonia, Argentina, based on morphological and molecular data. Preferences by size and sex of the intermediate host and seasonal variation of this parasite are provided, contributing to the knowledge of this host-parasite association.Centro de Estudios Parasitológicos y de Vectore

Juquitiba-like Hantavirus from 2 Nonrelated Rodent Species, Uruguay

Serologic and genetic analyses indicate that a Juquitiba-like hantavirus circulates in Maldonado, Uruguay. This virus is carried by 2 rodent species, Oligoryzomys nigripes and Oxymycterus nasutus. The same hantavirus in 2 nonrelated species can be explained by a spillover infection or a host-switching event

The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity

Akodon, with about 42 living species, is the most diverse genus of the subfamily Sigmodontinae. The Akodon boliviensis species group includes small-bodied, morphologically similar forms inhabiting Altiplano grasslands and grassland/forest ecotones of the eastern slope of the Andes, from central Peru to central Argentina. Northwestern Argentina contains the largest diversity of species of the group; the taxonomic treatment of these species has been based largely on unsupported and some weakly based opinions as underscored by recurrent changes. Based on morphologic and molecular data we assessed species limits among Argentinean populations of the Akodon boliviensis species group. We conclude that four species of the A. boliviensis species group inhabit northwestern Argentina. These are: A. boliviensis; A. caenosus (under which we synonymyze A. aliquantulus); A. spegazzinii (of which the nominal forms alterus, leucolimnaeus, and tucumanensis are junior synonyms); and A. sylvanus. Additionally, we described here a new species of the A. Boliviensis species group, Akodon polopi, which inhabits central Argentina. This is the only species of the A. boliviensis species group inhabiting the Sierras Grandes range (ca. 2000 m), mountain system of medium height isolated (ca., 600 km) from the main Andean chain by low elevation arid and semiarid environments. Additionally, our phylogenetic analysis suggests that the Akodon varius species group is polyphyletic.Fil: Jayat, Jorge Pablo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Investigaciones Ecológicas de las Yungas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ortiz, Pablo Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Salazar Bravo, Jorge. Texas Tech University; Estados UnidosFil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: D’Elía, Guillermo. Universidad de Concepción; Chil

The skull variation of the olive field mouse Abrothrix olivacea (Cricetidae: Abrotrichini) is localized and correlated to the ecogeographic features of its geographic distribution

The relationship between phenotypic variation and landscape heterogeneity has been extensively studied to understand how the environment influences patterns of morphological variation and differentiation of populations. Several studies had partially addressed intraspecific variation in the sigmodontine rodent Abrothrix olivacea, focusing on the characterization of physiological aspects and cranial variation. However, these had been conducted based on geographically restricted populational samples, and in most cases, the aspects characterized were not explicitly contextualized with the environmental configurations in which the populations occurred. Here, the cranial variation of A. olivacea was characterized by recording twenty cranial measurements in 235 individuals from 64 localities in Argentina and Chile, which widely cover the geographic and environmental distribution of this species. The morphological variation was analyzed and ecogeographically contextualized using multivariate statistical analyses, which also included climatic and ecological variation at the localities where the individuals were sampled. Results indicate that the cranial variation of this species is mostly clustered in localized patterns associated to the types of environments, and that the levels of cranial differentiation are higher among the populations from arid and treeless zones. Additionally, the ecogeographical association of cranial size variation indicate that this species does not follow Bergmann’s rule and that island populations exhibit larger cranial sizes compared to their continental counterparts distributed at the same latitudes. These results suggest that cranial differentiation among the populations of this species is not homogeneous throughout its geographic distribution, and that the patterns of morphological differentiation are also not completely consistent with the patterns of genetic structuring that have been described recently. Finally, the analyses performed to ponder morphological differentiation among populations suggest that the contribution of genetic drift in the formation of these patterns can be ruled out among Patagonian populations, and that the selective effect imposed by the environment could better explain them

Una Introducción a Los Mayores Sigmodontinos Vivientes: Revisión de Kunsia Hershkovitz, 1966 y Descripción de un Nuevo Género (Rodentia: Cricetidae)

A preliminary revision of Kunsia Hershkovitz, 1966 was made considering almost all the available specimens including type material of (in order of nomination) Mus principalis Lund, Scapteromys fronto Winge, S. gnambiquaræ M. Ribeiro, S. chacoensis Gyldenstolpe, and Kunsia fronto planaltensis Ávila-Pires. A new genus is proposed to allocate K. fronto and their subspecies. In addition, the latter are newly described and planaltensis is ranked as full species. The new genus is characterized by a unique combination of traits, including among others: large size, short tail (ca. 55% of combined head and body length), hispid dorsal hair, small tail scales covered by 3 hairs each one, rounded small-size ears, pes and manus unicolored, large nasals with acuminate posterior end reaching lacrimal level, distinctive zygomatic arch enlargement, large incisive foramina reaching first upper molar protocone, denticulate coronal suture open U-shaped, carotid circulatory pattern type 1, conspicuous coronal hypsodonty, developed mesolophids and protolophids + protoconulids in both first and second lower molars, first lower molar three rooted. Morphological comparisons of the new genus with Kunsia stricto sensu (restricted here to K. tomentosus) and Scapteromys (including S. aquaticus and S. tumidus) provide a basis for preliminary inferences about phylogenetic relationships. The fossil material from Bolivia and Argentina previously assigned to Kunsia is briefly addressed after a new study of the original remains, allowing us to conclude that they do not belong to the genus Kunsia neither to the new genus here proposed. The new genus is restricted to three recording localities in Brazil (one exclusively fossil) and one in Argentina, and had an unique record (Planaltina, Brasil) in the last five decades. Field work is urgently needed to assess the conservation status of these peculiar sigmodontine rodents.Se efectuó una revisión preliminar del género Kunsia Hershkovitz, 1966, empleando casi todos los especimenes disponibles e incluyendo el material tipo de las formas nominales (en orden de nominación): Mus principalis Lund, Scapteromys fronto Winge, S. gnambiquaræ M. Ribeiro, S. chacoensis Gyldenstolpe y Kunsia fronto planaltensis Ávila-Pires. Se propone un nuevo género para ubicar a K. fronto y sus subespecies. Adicionalmente, estas últimas son nuevamente descriptas y planaltensis es considerada como especie plena. El nuevo género se caracteriza por una combinación única de rasgos morfológicos, incluyendo entre otros: tamaño grande, cola corta (ca. 55% de la longitud cabeza-cuerpo combinados), pelaje dorsal híspido, escamas caudales pequeñas cubiertas por tres pelos cada una, orejas redondeadas y pequeñas, manos y pies unicolores, nasales largos posterioremente acuminados y alcanzando el nivel del lagrimal, ensanchamiento del arco cigomático, foramen incisivo largo alcanzando el protocono del primer molar superior, sutura coronal denticulada con forma de U, circulación carotídea de patrón 1, hipsodoncia coronal conspicua, mesolófidos y protolófidos + protoconúlidos desarrollados en los primeros y segundos molares inferiores, primer molar inferior con tres raíces. Las comparaciones morfológicas del nuevo género con Kunsia stricto sensu (restringido a Kunsia tomentosus) y Scapteromys (incluyendo S. aquaticus y S. tumidus) proveen una base para inferencias preliminares acerca de sus relaciones filogenéticas. El material fósil de Bolivia y Argentina previamente asignado a Kunsia es brevemente discutido sobre la base de un nuevo estudio a partir de los restos originales, concluyéndose que no pueden referirse ni al nuevo género aquí propuesto ni a Kunsia stricto sensu. El nuevo género está restringido a tres localidades en Brasil (una exclusivamente fósil) y una localidad en Argentina y tiene un único registro (Planaltina, Brasil) en las últimas cinco décadas. Se destaca la necesidad de urgentes trabajos de campo en orden de establecer el estatus de conservación de estos peculiares sigmodontinos

Revisión taxonómica de la rana marsupial Gastrotheca peruana (Amphibia: Hemiphractidae) en base al gen mitocondrial 16S

The taxonomic status of Gastrotheca peruana is evaluated using phylogenetic methods and 16S gene sequences. The maximum likelihood and Bayesian trees showed that the genetic variants of G. peruana form two clades that are not sister to each other. One of these clades is present in northern Perú and includes a specimen collected at the type locality of G. peruana dissimilis. The other clade is restricted to central Peru and contains individuals from type localities of two nominal forms, G. p. peruana and G. p. junensis, and is sister to G. aratia. Our results suggest that G. peruana sensu lato currently encompass two species. We restrict Gastrotheca peruana to populations from central Perú (departments of Ancash, Lima, Pasco and Junín) and assign populations from departments of La Libertad and Cajamarca to Gastrotheca dissimilis.Se revisa el estado taxonómico de Gastrotheca peruana usando métodos filogenéticos en base a secuencias de 16S rRNA. Los árboles de máxima verosimilitud y Bayesiano mostraron que las variantes génicas de G. peruana forman dos clados que no son hermanos. Uno de estos clados se distribuye en el norte de Perú, incluyendo un individuo procedente de la localidad típica de G. peruana dissimilis. El segundo clado está restringido al centro de Perú y contiene individuos de las localidades tipo de dos formas nominales, G. p. peruana y G. p. junensis, y es hermano de G. aratia. De esta forma, reconocemos dos especies dentro de lo que actualmente se conoce como G. peruana. Restringimos Gastrotheca peruana a las poblaciones del centro de Perú (departamentos de Ancash, Lima, Pasco y Junín) y asignamos Gastrotheca dissimilis a las poblaciones de los departamentos de La Libertad y Cajamarca

Genomic insights into the mystery of mouse mummies on the summits of Atacama volcanoes

Our understanding of the limits of animal life is continually revised by scientific exploration of extreme environments. Here we report the discovery of mummified cadavers of leaf-eared mice, Phyllotis vaccarum, from the summits of three different Andean volcanoes at elevations 6,029–6,233 m above sea level in the Puna de Atacama in Chile and Argentina. Such extreme elevations were previously assumed to be completely uninhabitable by mammals. In combination with a live-captured specimen of the same species from the nearby summit of Volcán Llullaillaco (6,739 m),1 the summit mummies represent the highest altitude physical records of mammals in the world. We also report a chromosome-level genome assembly for P. vaccarum that, in combination with a whole-genome re-sequencing analysis and radiocarbon dating analysis, provides insights into the provenance and antiquity of the summit mice. Radiocarbon data indicate that the most ancient of the mummies are, at most, a few centuries old. Genomic polymorphism data revealed a high degree of continuity between the summit mice and conspecifics from lower elevations in the surrounding Altiplano. Genomic data also revealed equal numbers of males and females among the summit mice and evidence of close kinship between some individuals from the same summits. These findings bolster evidence for resident populations of Phyllotis at elevations \u3e6,000 m and challenge assumptions about the environmental limits of vertebrate life and the physiological tolerances of small mammals