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Santa Rosa, Argentina

The National University of La Pampa is an Argentine national university, situated in the city of Santa Rosa, capital of La Pampa Province. Wikipedia.

Kleingrass (Panicum coloratum L. var. coloratum) is a perennial warm-season grass that begins its growing season later in the spring than does weeping lovegrass (Eragrostis curvula (Schrad.) Nees), which suggests that combining weeping lovegrass with kleingrass in a grazing sequence could increase livestock production. The objectives of this study were to determine the seasonal and inter-annual variation of the patterns of the accumulation of dry matter (DM) and the percentage of crude protein (CP) in P. coloratum, cv. Verde, in the semiarid Pampean region of Argentina. This study was performed during four growing seasons in a 3.0 ha pasture of kleingrass that was sown in the spring of 1996. The forage samples were gathered at biweekly intervals and were separated into leaf blade, stems (including sheaths and inflorescence) and senescent material. Finally, patterns of dry matter accumulation and the percentage of crude protein were evaluated in relationship to the thermal time accumulated from early October to late February. In comparison with the other growing seasons evaluated, the third growing season had less (P ≤ 0.01) accumulation of dry matter and a higher (P ≤ 0.01) proportion of green leaf blade and CP. Dry matter accumulation increased with increases in the thermal time. The CP percentage of the total biomass and of the plant parts declined as thermal time increased, and this coincided with a reduction in the proportion of green leaves and the CP percentage in each plant part. Management decisions depend on an accurate assessment of the change in sward structure and nutritive value during the growing season. The results of this study will allow selection of the appropriate grazing time and the management of sequential grazing of warm-season grasses. Source

Muino W.A.,National University of La Pampa
Ethnobotany Research and Applications

This paper is an ethnobotanical study of cattle farming in the western Pampa region of Argentina, an arid region with very scarce rainfall and a population consisting mainly of Criollo farmers. A total of 68 rural settlers were interviewed, providing information on 69 specific and infraspecific taxa. Plants were classified into the following categories according to use: forage, toxic species or species with adverse effects on animals, use in rural constructions, tools, and those with veterinary applications. Data include native, naturalized and cultivated species. They revealed a diverse group of forage plants, according to the type of livestock, and very few toxic plants. Veterinary applications were related to first aid cases. In rural construction, plants were mostly used for fencing paddocks and corrals. The results of this study show the acute level of perception and detailed knowledge of the plant environment held by this farming community in relation to their main economic activity. Source

Melchor R.N.,National University of La Pampa
Palaeogeography, Palaeoclimatology, Palaeoecology

This is a review of the main uses of vertebrate trace fossils, ichnofabrics and ichnofacies in the palaeoenvironmental analysis of sedimentary sequences. The article accounts for the significant developments produced in the last three decades, including the application of the ichnofacies concept to vertebrate trace fossils. Recognition of footprints in cross-sectional view and their distinction from inorganic structures and burrow fills, is first discussed. The response of different substrates, showing contrasting water content and imprinted by different animals or devices, is compared in terms of the morphology of the resultant footprint. Trackways with sand crescents are typical of aeolian cross-strata and are absent in associated flat-lying to low-angle deposits. Thick packages of highly bioturbated sandy dune and interdune sediments have been interpreted as reflecting periods of increased rainfall. Neoichnological observations in modern lake basins suggest that distinct zones can be recognized in the margins of fossil ponds and lakes, including onshore, shoreline and shallow subaqueous zones. Abundant flamingo-like footprints and flamingo nest mounds are good indicators of alkaline and/or saline lake waters. Hippopotamus trails are found closely associated with modern and fossil freshwater wetlands. Dinosaur and pterosaur swim traces from lacustrine and fluvial deposits can be used to estimate water depth. Turtle, crocodile, amphibian, hippopotamus and fish swim traces allow one to infer a subaqueous substrate. Certain modern intertidal fish feeding traces are oriented with the predominant tidal current and can be used as palaeocurrent indicators. The preferential orientation of tetrapod trackways in lacustrine and fluvial deposits is analyzed. Vertebrate trace fossils can help to infer discharge variability in fluvial channels. The descriptions of vertebrate ichnofabrics are commonly limited to heavily bioturbated beds due to trampling by vertebrates, and to a few examples of ichnofabrics with discrete trace fossils. The nature and implications of the recognized vertebrate ichnofacies are still being debated and have a limited utility in palaeoenvironmental analysis. The distinction of a potential vertebrate burrow ichnofacies in carbonate-bearing palaeosols is proposed to represent well-drained soils, developed under arid or semiarid climate. © 2015 Elsevier B.V. Source

Salto C.,National University of La Pampa | Alba E.,University of Malaga
Applied Intelligence

This paper investigates a new heterogeneous method that dynamically sets the migration period of a distributed Genetic Algorithm (dGA). Each island GA of this multipopulation technique self-adapts the period for exchanging information with the other islands regarding the local evolution process. Thus, the different islands can develop different migration settings behaving like a heterogeneous dGA. The proposed algorithm is tested on a large set of instances of the Max-Cut problem, and it can be easily applied to other optimization problems. The results of this heterogeneous dGA are competitive with the best existing algorithms, with the added advantage of avoiding time-consuming preliminary tests for tuning the algorithm. © 2011 Springer Science+Business Media, LLC. Source

Sterli J.,CONICET | de la Fuente M.S.,CONICET | Umazano A.M.,National University of La Pampa
Gondwana Research

New cranial and postcranial remains of the Gondwanan meiolaniform turtle Chubutemys copelloi Gaffney, Rich, Vickers-Rich, Constantine, Vacca and Kool 2007 from the Lower Cretaceous Puesto La Paloma Member of the Cerro Barcino Formation (Chubut province, Patagonia, Argentina) are presented, described, and compared in this contribution. Carapace and plastral remains, pectoral and pelvic girdle, cervical and thoracic vertebrae, and the left maxilla and jugal are the new recovered elements from C. copelloi. These new remains were found in 2008 in Turtle Town locality, the same site where the holotype and referred specimens of C. copelloi had been found in 1997. The facies analysis of the sedimentary succession in Turtle Town and surrounding areas suggests a paleoenvironment constituted by a broad alluvial plain with influx of volcanic ash-falls, whose deposits were disturbed by pedogenesis or reworked by current flows that supplied water and sediment in ponded areas. The presence of a very thin shell, broad vertebrals (broader than pleurals), the presence of a shallow nuchal notch with the vertebral 1 almost reaching the anterior border of the carapace, the presence of costo-peripheral fontanelles, and the presence of an ectepicondylar canal in the humerus, are the most notable features provided by the new remains. A cladistic analysis has been performed to test the phylogenetic position of C. copelloi. This phylogeny corroborates the basal position of C. copelloi among Meiolaniformes. The plausible phylogenetic relationships of the clade Meiolaniidae with other Gondwanan (e.g., Otwayemys cunicularius Gaffney, Kool, Brinkman, Rich, and Vickers-Rich 1998) or Laurasian Lower Cretaceous taxa (e.g., sinochelyids) are also discussed in this contribution. Taxa included in Meiolaniformes have been mainly found in Gondwana and as the most basal taxon was found in Patagonia, paleobiogeographic studies suggest this clade originated in South America. Due to the basal position of C. copelloi among Meiolaniformes the discovery of more and previously unknown remains of this species sheds light on the origin and early evolution of this curious clade. © 2013 International Association for Gondwana Research. Source

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