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Sample records for northwestern venezuelan andes

  1. Sedimentological evidence for early uplift (Oligocene) of the Venezuelan Andes

    SciTech Connect

    Higgs, R. )

    1993-02-01

    The ongoing Andean orogeny is generally believed to have started in Miocene time. However, sedimentological studies of a Cenozoic clastic section in the northwestern foothills of the Venezuelan Andes (Rio Chama) yield two lines of evidence that uplift was already underway in the Oligocene. (1) Thick Oligocene shales (Leon Formation; 300m) are dark gray and bioturbated. Pyrite is absent and the fauna is restricted to benthonic forms (R. Pittelli), suggesting deposition in a brackish lake rather than the sea. The shales occur throughout the plains northwest of the Andes. Such a large, long-lived lake implies isolation form the sea, suggesting that the Andes were already high in the Oligocene, forming a topographically confined basin similar to the modern Lake Maracaibo. Like modern Lake Maracaibo, there was a tenuous connection with the sea, allowing marine incursions whenever eustatic sea level was high enough, as shown by horizons with marine fossils at other localities. (2) The overlying Oligocene-Miocene succession which caps the Rio Chama section (Caracol Member, Chama Formation; basal Betijoque Formation) includes fluvial channel sands with pebbles which can be matched to Cretaceous cherts of the adjacent Andes (Ftanita de Tachira). The first pebbles appear in the Caracol Member (Oligocene). They are thus regarded as the initial Andean molasse deposits and their deposition has continued to the present day.

  2. 3D Geomodeling of the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Monod, B.; Dhont, D.; Hervouet, Y.; Backé, G.; Klarica, S.; Choy, J. E.

    2010-12-01

    The crustal structure of the Venezuelan Andes is investigated thanks to a geomodel. The method integrates surface structural data, remote sensing imagery, crustal scale balanced cross-sections, earthquake locations and focal mechanism solutions to reconstruct fault surfaces at the scale of the mountain belt into a 3D environment. The model proves to be essential for understanding the basic processes of both the orogenic float and the tectonic escape involved in the Plio-Quaternary evolution of the orogen. The reconstruction of the Bocono and Valera faults reveals the 3D shape of the Trujillo block whose geometry can be compared to a boat bow floating over a mid-crustal detachment horizon emerging at the Bocono-Valera triple junction. Motion of the Trujillo block is accompanied by a generalized extension in the upper crust accommodated by normal faults with listric geometries such as for the Motatan, Momboy and Tuñame faults. Extension may be related to the lateral spreading of the upper crust, suggesting that gravity forces play an important role in the escape process.

  3. Investigations on vertical crustal movements in the Venezuelan Andes by gravimetric methods

    NASA Technical Reports Server (NTRS)

    Drewes, H.

    1978-01-01

    A precise gravimetric network has been installed in the Venezuelan Andes to study eventual gravity changes due to vertical tectonic movements. The design and the measurements of the network are described and the accuracy is estimated. In the center of the region a local gravity network has been reobserved three times. The detected variations are discussed. In order to obtain a genuine statement as far as possible about the significance of observed gravity changes, requirements for the procedure of monitoring precise gravity networks are pointed out.

  4. Essential Oil Composition and Antibacterial Activity of Hyptis colombiana from the Venezuelan Andes.

    PubMed

    Flores, Mayalin; Rojas, Luis; Aparicio, Rosa; Lucena, María Eugenia; Usubillaga, Alfredo

    2015-10-01

    Hyptis colombiana is an aromatic shrub native to the Colombian and Venezuelan Andes. Aerial parts were collected in Mérida State at about 3100 m above sea level in February 2005, and May and October 2006. The essential oil was found to contain germacrene D and β-caryophyllene as main constituents (about 50%). The February 2005 and October 2006 oils were found to have antibacterial activity against Staphylococcus aureus, but not the May 2006 oil, probably due to the lack of some minor constituent.

  5. Essential Oil Composition and Antibacterial Activity of Hyptis colombiana from the Venezuelan Andes.

    PubMed

    Flores, Mayalin; Rojas, Luis; Aparicio, Rosa; Lucena, María Eugenia; Usubillaga, Alfredo

    2015-10-01

    Hyptis colombiana is an aromatic shrub native to the Colombian and Venezuelan Andes. Aerial parts were collected in Mérida State at about 3100 m above sea level in February 2005, and May and October 2006. The essential oil was found to contain germacrene D and β-caryophyllene as main constituents (about 50%). The February 2005 and October 2006 oils were found to have antibacterial activity against Staphylococcus aureus, but not the May 2006 oil, probably due to the lack of some minor constituent. PMID:26669118

  6. Two new, brachypterous Limnellia species from the Venezuelan Andes (Diptera: Ephydridae).

    PubMed

    Costa, Daniel N R; Savaris, Marcoandre; Marinoni, Luciane; Mathis, Wayne N

    2016-01-01

    Two new, brachypterous species of Limnellia are described from specimens collected in the Venezuelan Andes: L. vounitis (Trujillo: Bocon, La Cristalina (Andes; 09°14.7'N, 70°19.1'W; 2500 m)) and L. flavifrontis (Mérida: Mérida, Sierra Nevada National Park (Laguna Negra; 8°47.1'N; 70°48.4'W; 3300 m)). To facilitate identification of these unusual species, we have included a diagnosis of the tribe Scatellini and of the genus Limnellia and have also provided an annotated key to the South American genera of this tribe. The descriptions are supplemented with illustrations, photographs, and scanning electron micrographs of external structures and structures of the male terminalia. PMID:27470858

  7. Petroleum systems of the northwestern Tachira Depression, Venezuelan Andes

    SciTech Connect

    Ostos, M.; Callejon, A.; Vivan, M.A.

    1996-08-01

    The tectonic evolution and sedimentation of the Tachira Depression was controlled by Paleozoic crustal scale discontinuities, partly or fully inverted during the pre-Andean (Paleocene) and Andean (Neogene) deformations. Outcrop samples were analyzed for source rock evaluation. La Luna, Los Cuervos and Carbonera formations are excellent potential oil sources. However, La Luna and Los Cuervos were the oil-generating units according to ID-modelling (BasinMod), defining La Luna-K/T(!) and Los Cuervos-K/T(!) systems. La Luna contains good to excellent oil prone kerogen type I-II, while Los Cuervos contains gas-oil prone type II-III. Oil seeps, expelled at the peak of oil generation stage (0.85-0.90 %R{sub o}), were derived from marine sources and genetically correlated to La Luna. No correlation of seeps with Los Cuervos was found. Although it exists to the southeast (Burgua depression). Potential clastic and carbonatic Cretaceous (K) and Tertiary (T) reservoirs and regional seals of the Colon and Leon Formations are widespread in the depression. Modelling results indicate that migration started during the Middle Miocene, related to the Andean tectonic loading. The subsequent migration took place northward, to be finally stopped against the Capacho and Bocono fault systems.

  8. Trench investigation along the Merida section of the Bocono fault (central Venezuelan Andes), Venezuela

    USGS Publications Warehouse

    Audemard, F.; Pantosti, D.; Machette, M.; Costa, C.; Okumura, K.; Cowan, H.; Diederix, H.; Ferrer, C.

    1999-01-01

    The Bocono fault is a major NE-SW-trending, dextral fault that extends for about 500 km along the backbone of the Venezuelan Andes. Several large historical earthquakes in this region have been attributed to the Bocono fault, and some of these have been recently associated with specific parts through paleoseismologic investigations. A new trench study has been performed, 60 km to the northeast of Merida in the central Venezuelan Andes, where the fault forms a releasing bend, comprising two conspicuous late Holocene fault strands that are about 1 km apart. The southern and northern strands carry about 70% and 30% (respectively) of the 7-10 mm/yr net slip rate measured in this sector, which is based on a 40 vs. 85-100 m right-lateral offset of the Late Pleistocene Los Zerpa moraines. A trench excavated on the northern strand of the fault (near Morros de los Hoyos, slightly northeast of Apartaderos) across a twin shutter ridge and related sag pond exposed two main fault zones cutting Late Pleistocene alluvial and Holocene peat deposits. Each zone forms a shutter ridge with peat deposits ponded against the uplifted block. The paleoearthquake reconstruction derived from this trench allow us to propose the occurrence of at least 6-8 earthquakes in the past 9000 yr, yielding a maximum average recurrence interval of about 1100-1500 yr. Based on the northern strands average slip rate (2.6 mm/yr), such as earthquake sequence should have accommodated about 23 m of slip since 9 ka, suggesting that the maximum slip per event ranges between 3 and 4 m. No direct evidence for the large 1812 earthquake has been found in the trench, although this earthquake may have ruptured this section of the fault. Further paleoseismic studies will investigate the possibility that this event occurred in the Bocono fault, but ruptured mainly its southern strand in this region.

  9. Low temperature resistance in saplings and ramets of Polylepis sericea in the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Rada, Fermín; García-Núñez, Carlos; Rangel, Sairo

    2009-09-01

    The frequent occurrence of all year-round below zero temperatures in tropical high mountains constitutes a most stressful climatic factor that plants have to confront. Polylepis forests are found well above the continuous forest line and are distributed throughout the Andean range. These trees require particular traits to overcome functional limitations imposed on them at such altitudes. Considering seedling and sapling stages as filter phases in stressful environments, some functional aspects of the regeneration of Polylepis sericea, a species associated to rock outcrops in the Venezuelan Andes, were studied. We characterized microclimatic conditions within a forest, in a forest gap and surrounding open páramo and determined low temperature resistance mechanisms in seedlings, saplings and ramets. Conditions in the forest understory were more stable compared to the forest gaps and open surrounding páramo. Minimum temperatures close to the ground were 3.6 °C lower in the open páramo compared to the forest understory. Maximum temperatures were 9.0 °C higher in the open páramo. Ice nucleation and injury temperatures occurred between -6 and -8 °C for both ramets and saplings, an evidence of frost avoidance to low nighttime temperatures. In this particular forest, this resistance ability is determinant in their island-like distribution in very specific less severe temperature habitats.

  10. Palynological signal of the Younger Dryas in the tropical Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Rull, Valentí; Stansell, Nathan D.; Montoya, Encarni; Bezada, Maximiliano; Abbott, Mark B.

    2010-11-01

    The occurrence, or not, of the Younger Dryas cold reversal in the tropical Andes remains a controversial topic. This study reports a clear signal for this event in the Venezuelan Andes, employing high-resolution palynological analysis of a well-dated sediment core from Laguna de Los Anteojos, situated around 3900 m elevation, within grass páramo vegetation. The lake is surrounded by some Polylepis forests which are close to their upper distribution limit. The section of the core discussed here is 150-cm long and dated between about 14.68 and 9.35 cal kyr BP, using a polynomial age-depth model based on six AMS radiocarbon dates. Between 12.86 and 11.65 cal kyr BP, an abrupt shift occurred in the pollen assemblage, manifested by a decline of Podocarpus, Polylepis and Huperzia, combined with an increase in Poaceae and Asteraceae. The aquatic pteridophyte Isoëtes also decreased and disappeard, and the algae remains show their minimum values. Pollen assemblages from the Younger Dryas interval show maximum dissimilarity values compared with today's pollen assemblage, and are more similar to modern analogs from superpáramo vegetation, growing at elevations 400-500 m higher. A lowering of vegetation zones of this magnitude corresponds to a temperature decline of between 2.5 and 3.8 °C. During this colder interval lake levels may have been lower, suggesting a decrease in available moisture. The vegetation shift documented in Anteojos record between 12.86 and 11.65 cal kyr BP is comparable to the El Abra Stadial in the Colombian Andes but it differs in magnitude. The Anteojos shift is better dated and coincides with the Younger Dryas chron as recorded in the Cariaco Basin sea surface temperature reconstructions and records of continental runoff, as well as in the oxygen isotope measurements from the Greenland ice cores. When compared to other proxies of quasi-immediate response to climate, the time lag for the response of vegetation to climate is found to be negligible

  11. Comparison of the chemical composition of Valeriana parviflora essential oils collected in the Venezuelan Andes in two different seasons.

    PubMed

    Fernández, Sammy; Rondón, María; Rojas, Janne; Morales, Antonio; Rojas-Fermin, Luis

    2015-04-01

    The essential oils obtained by hydrodistillation of the aerial parts of Valerianaparviflora (Trevir) BM Vadillo, an endemic species of the Venezuelan Andes, collected from the same location in two different seasons (dry and rainy) of the year, were analyzed by GC/MS. The essential oil obtained during the dry season showed linalool (11.9%), eugenol (8.9%), p-menth-l-en-9-al (8.7%) and α-terpineol (7.7%) as main components, while the oil obtained from the rainy season collection showed o-xylol (16.2%), 3-methyl isovaleric acid (10.6%) and geranial (9.5%) as major compounds. Some of the differences in the composition of these oils might be due to the climatic conditions at the time of harvesting.

  12. Comparison of the chemical composition of Valeriana parviflora essential oils collected in the Venezuelan Andes in two different seasons.

    PubMed

    Fernández, Sammy; Rondón, María; Rojas, Janne; Morales, Antonio; Rojas-Fermin, Luis

    2015-04-01

    The essential oils obtained by hydrodistillation of the aerial parts of Valerianaparviflora (Trevir) BM Vadillo, an endemic species of the Venezuelan Andes, collected from the same location in two different seasons (dry and rainy) of the year, were analyzed by GC/MS. The essential oil obtained during the dry season showed linalool (11.9%), eugenol (8.9%), p-menth-l-en-9-al (8.7%) and α-terpineol (7.7%) as main components, while the oil obtained from the rainy season collection showed o-xylol (16.2%), 3-methyl isovaleric acid (10.6%) and geranial (9.5%) as major compounds. Some of the differences in the composition of these oils might be due to the climatic conditions at the time of harvesting. PMID:25973503

  13. A new species of Cryptotis (Mammalia, Eulipotyphla, Soricidae) from the Sierra de Perijá, Venezuelan-Colombian Andes

    USGS Publications Warehouse

    Quiroga-Carmona, Marcial; Woodman, Neal

    2015-01-01

    The Sierra de Perijá is the northern extension of the Cordillera Oriental of the Andes and includes part of the border between Colombia and Venezuela. The population of small-eared shrews (Mammalia, Eulipotyphla, Soricidae, Cryptotis) inhabiting the Sierra de Perijá previously was known from only a single skull from an individual collected in Colombia in 1989. This specimen had been referred to alternatively as C. thomasi and C. meridensis, but more precise definition of the known Colombian and Venezuelan species of Cryptotis has since excluded the Sierra de Perijá population from any named species. The recent collection of a specimen from the Venezuelan slope of Sierra de Perijá, prompted us to re-evaluate the taxonomic status of this population and determine its relationship with other Andean shrews. Our examination of the available specimens revealed that they possess a unique suite of morphological and morphometrical characters, and we describe the Sierra de Perijá population as a new species in the South American C. thomasi species group. Recognition of this new species adds to our knowledge of this genus in South America and to the biodiversity of the Sierra de Perijá.

  14. Recent trends in human migrations: the case of the Venezuelan Andes.

    PubMed

    Suarez, M M; Torrealba, R

    1982-01-01

    Changes in world capitalism caused prices of traditional raw materials to fall and new energy demands to arise at the end of the 19th and beginning of the 20th century. The Andean countries witnessed the fall in the value of their exports and began to receive large flows of foreign investment in mining and industry. Consequently, urban economies were strengthened and demographic patterns were changed. This led to the internal migrations and to a process of social change. These consequences are summarized from relevant studies focusing on Ecuador, Colombia, and Venezuela. Since the 1960s a compendium of information has become available which highlights the causes of the migration, migration patterns, the composition of migratory movements, and the mechanisms that the migrant uses to establish himself/herself in the city. Preston (1969) distinguished 2 migratory patterns in Ecuador: rural to urban, with migratory flows from the rural areas to urban centers and new industrial cities that experienced development and high demand for unskilled labor at comparatively high wages: and rural to rural, based on the movement of population from depressed rural areas to other areas in which programs for colonization or commercial agriculture have been promoted. In a study of Colombia, McGreevey (1968) identifies the lack of cultivatable land, rural violence in certain departments, and other economic and family causes as the principal factors that induced migrations to the cities. The study emphasizes that the predominant model of movement relates to "fill in" migration. The spatial mobility of the Venezuelan Andean population was initially outlined in a voluminous report on economic and social problems of the region (1954). The study indicates that during the intercensal period 1941-50 cities grew much more rapidly than rural "municipos" and that the drive to find employment and earn a living were the most important motives in the movement of peasants to the cities. All of the

  15. Volatile Constituents from the Flowers of Spathodea campanulata from the Venezuelan Andes.

    PubMed

    Villarreal, Silvana; Jaimez, Deisy; Moreno, Sindy; Rojas, Luis B; Usubillaga, Alfredo; Rodríguez, María

    2015-11-01

    The chemical composition is reported of the essential oil obtained by hydrodistillation of Spathodea campanulata P. Beauv. (Bignoniaceae) flowers collected in the Andes region of Venezuela. Thirty compounds were characterized, representing 96.5% of the total oil composition; benzyl benzoate (17.5%) was the major constituent. Others major components were a mixture of geranyl acetone with a-humulene (12.7%), β-caryophyllene (9.5%), farnesyl acetone (6.0%), aromadendrene (4.3%), α-gurjunene (3.9%) and tricosane (3.7%). This is the first report related to the chemical composition of the essential oil of S. campanulata flowers.

  16. Freezing tolerance in grasses along an altitudinal gradient in the Venezuelan Andes.

    PubMed

    Márquez, Edjuly J; Rada, Fermín; Fariñas, Mario R

    2006-12-01

    The tropical high Andes experience greater daily temperature oscillations compared to seasonal ones as well as a high frequency of night frost occurrence year round. Survival of organisms, under such environmental conditions, has been determined by selective forces which have evolved into adaptations including avoidance or tolerance to freezing. These adaptations have been studied in different species of trees, shrubs and perennial herbs in páramo ecosystems, while they have not been considered in grasses, an important family of the páramo. In order to understand survival of Poaceae, resistance mechanisms were determined. The study was performed along an altitudinal gradient (2,500-4,200 m a.s.l.) in the páramo. Supercooling capacity and frost injury temperature were determined in nine species in order to establish cold resistance mechanisms. Grasses registered a very low supercooling capacity along the altitudinal gradient, with ice formation between -6 and -3 degrees C. On the other hand, frost injury temperature oscillated between -18 and -7 degrees C. Our results suggest that grasses exhibit freezing tolerance as their main cold resistance mechanism. Since grasses grow at ground level, where greatest heat loss takes place, tolerance may be related to this life form as reported for other small life forms. PMID:17024382

  17. Tectonic, volcanic, and climatic geomorphology study of the Sierras Pampeanas Andes, northwestern Argentina

    NASA Technical Reports Server (NTRS)

    Bloom, A. L.; Strecker, M. R.; Fielding, E. J.

    1984-01-01

    A proposed analysis of Shuttle Imaging Radar-B (SIR-B) data extends current research in the Sierras Pampeanas and the Puna of northwestern Argentina to the determination - by the digital analysis of mountain-front sinuousity - of the relative age and amount of fault movement along mountain fronts of the late-Cenozoic Sierras Pampeanas basement blocks; the determination of the age and history of the boundary across the Andes at about 27 S latitude between continuing volcanism to the north and inactive volcanism to the south; and the determination of the age and extent of Pleistocene glaciation in the High Sierras, as well as the comparative importance of climatic change and tectonic movements in shaping the landscape. The integration of these studies into other ongoing geology projects contributes to the understanding of landform development in this active tectonic environment and helps distinguish between climatic and tectonic effects on landforms.

  18. A new species of Andean poison frog, Andinobates (Anura: Dendrobatidae), from the northwestern Andes of Colombia.

    PubMed

    Amézquita, Adolfo; Márquez, Roberto; Medina, Ricardo; Mejía-Vargas, Daniel; Kahn, Ted R; Suárez, Gustavo; Mazariegos, Luis

    2013-01-01

    The poison frogs of the Colombian Andes, Pacific lowlands and Panama have been recently recognized as a new, monophyletic and well-supported genus: Andinobates. The species richness and distribution within Andinobates remain poorly understood due to the paucity of geographic, genetic and phenotypic data. Here we use a combination of molecular, bioacoustic and morphometric evidence to describe a new species of Andean poison frog: Andinobates cassidyhornae sp. nov. from the high elevation cloud forests of the Colombian Cordillera Occidental, in the northwestern Andes. The new species is associated to the bombetes group and characterized by a unique combination of ventral and dorsal color patterns. Data on 1119 bp from two mitochondrial markers allowed us to reject the null hypotheses that A. cassidyhornae sp. nov. is part of the phenotypically similar and geographically less distant species: A. opisthomelas, A. virolinensis or A. bombetes. The best available phylogenetic trees and the genetic distance to other Andinobates species further support this decision. Altogether, the advertisement call parameters unambiguously separated A. cassidyhornae sp. nov. calls from the calls of the three closest species. The new species adds to a poorly known and highly endangered genus of poison frogs that requires further studies and urgent conservation measures. PMID:26120702

  19. A new species of Andean poison frog, Andinobates (Anura: Dendrobatidae), from the northwestern Andes of Colombia.

    PubMed

    Amézquita, Adolfo; Márquez, Roberto; Medina, Ricardo; Mejía-Vargas, Daniel; Kahn, Ted R; Suárez, Gustavo; Mazariegos, Luis

    2013-01-01

    The poison frogs of the Colombian Andes, Pacific lowlands and Panama have been recently recognized as a new, monophyletic and well-supported genus: Andinobates. The species richness and distribution within Andinobates remain poorly understood due to the paucity of geographic, genetic and phenotypic data. Here we use a combination of molecular, bioacoustic and morphometric evidence to describe a new species of Andean poison frog: Andinobates cassidyhornae sp. nov. from the high elevation cloud forests of the Colombian Cordillera Occidental, in the northwestern Andes. The new species is associated to the bombetes group and characterized by a unique combination of ventral and dorsal color patterns. Data on 1119 bp from two mitochondrial markers allowed us to reject the null hypotheses that A. cassidyhornae sp. nov. is part of the phenotypically similar and geographically less distant species: A. opisthomelas, A. virolinensis or A. bombetes. The best available phylogenetic trees and the genetic distance to other Andinobates species further support this decision. Altogether, the advertisement call parameters unambiguously separated A. cassidyhornae sp. nov. calls from the calls of the three closest species. The new species adds to a poorly known and highly endangered genus of poison frogs that requires further studies and urgent conservation measures.

  20. [Chemical composition of fresh bee pollen collected in the Misintá páramo from the Venezuelan Andes].

    PubMed

    Vit, Patricia; Santiago, B

    2008-12-01

    Venezuelan bee pollen has not been characterized, and marketing is not regulated. Pollen is consumed for apitherapeutical purposes for its nutritional and medicinal properties. This product of the hive is the most popular after honey; therefore it is necessary to characterize and to value it to initiate a database to support the proposal of a norm for bee pollen quality control. Samples of bee pollen collected by bees in the Misintá páramo of Mérida state were characterized accoridng to the chemical composition (moisture, ash, fat, pH, proteins) of four color fractions (yellow, orange, ochre, green). Yellow pollen was the most frequent fraction, with 2.18 g ash/100 g, 5.37 g ether extract/100 g, 14.88 g moisture/100 g, and 37.32 g proteins/100 g. PMID:19368304

  1. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes.

    PubMed

    Langer, Max C; Rincón, Ascanio D; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W M

    2014-10-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U-Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal-vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic-Jurassic boundary. PMID:26064540

  2. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes.

    PubMed

    Langer, Max C; Rincón, Ascanio D; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W M

    2014-10-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U-Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal-vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic-Jurassic boundary.

  3. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes

    PubMed Central

    Langer, Max C.; Rincón, Ascanio D.; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W. M.

    2014-01-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U–Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal–vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic–Jurassic boundary. PMID:26064540

  4. Petroleum systems at the triple point between the Merida Andes, the eastern cordillera of Colombia and the Guayana shield: The petroleum geology of the Colombian-Venezuelan Border

    SciTech Connect

    Chigne, N.; Loureiro, D.; Rojas, L.

    1996-08-01

    The sinistral Bramon-Bucaramanga shear zone, in conjunction with the southeastern vergent Falla Borde Llanero and the northwestern vergent frontal thrust of the Merida Andes, defines a complex area where tectonic transport shows crustal scale shift. Palinspastic restorations have been used as a base for the identification and reconstruction of the evolving petroleum systems, showing that several of the discontinuities within this collage served as barriers for major oil accumulations. The main oil generating unit of the region is a 200-m-thick sequence of Cenomanian-Turonian rocks representing a variety of facies, from siliciclastic mudstones to finely laminated limestones. Sequence stratigraphy at well-log scale combined with seismic profiles has helped to identify and map the most important reservoir-seal couples within Late Cretaceous and late Eocene-Early Miocene megasequences. One- and two-dimensional modelling of kerogen maturation suggest a major phase of oil expulsion during Early Miocene. Loading of the source rock below Upper Miocene to Holocene thrust and/or coeval foredeep sediments has developed a petroleum system that is active today. Oil migrated toward the local highs from active kitchens located to the west-southwest.

  5. Cenozoic foreland basin system in the central Andes of northwestern Argentina: Implications for Andean geodynamics and modes of deformation

    NASA Astrophysics Data System (ADS)

    Decelles, P. G.; Carrapa, B.; Horton, B. K.; Gehrels, G. E.

    2011-12-01

    Cenozoic strata in the central Andes of northwestern Argentina record the development and migration of a regional foreland basin system analogous to the modern Chaco-Paraná alluvial plain. Paleocene-lower Eocene fluvial and lacustrine deposits are overlain by middle-upper Eocene hypermature paleosols or an erosional disconformity representing 10-15 Myr. This `supersol/disconformity' zone is traceable over a 200,000 km2 area in the Andean thrust belt, and is overlain by 2-6 km of upward coarsening, eastward thinning, upper Eocene through lower Miocene fluvial and eolian deposits. Middle Miocene-Pliocene fluvial, lacustrine, and alluvial fan deposits occupy local depocenters with contractional growth structures. Paleocurrent and petrographic data demonstrate westerly provenance of quartzolithic and feldspatholithic sediments. Detrital zircon ages from Cenozoic sandstones cluster at 470-491, 522-544, 555-994, and 1024-1096 Ma. Proterozoic-Mesozoic clastic and igneous rocks in the Puna and Cordillera Oriental yield similar age clusters, and served as sources of the zircons in the Cenozoic deposits. Arc-derived zircons become prominent in Oligo-Miocene deposits and provide new chronostratigraphic constraints. Sediment accumulation rate increased from ˜20 m/Myr during Paleocene-Eocene time to 200-600 m/Myr during the middle to late Miocene. The new data suggest that a flexural foreland basin formed during Paleocene time and migrated at least 600 km eastward at an unsteady pace dictated by periods of abrupt eastward propagation of the orogenic strain front. Despite differences in deformation style between Bolivia and northwestern Argentina, lithosphere in these two regions flexed similarly in response to eastward encroachment of a comparable orogenic load beginning during late Paleocene time.

  6. Tectonostratigraphic reconstruction Cretaceous volcano-sedimentary in the northwestern Andes: from extensional tectonics to arc accretion.

    NASA Astrophysics Data System (ADS)

    Zapata, S.; Patino, A. M.; Cardona, A.; Mejia, D.; Leon, S.; Jaramillo, J. S.; Valencia, V.; Parra, M.; Hincapie, S.

    2014-12-01

    Active continental margins characterized by continuous convergence experienced overimposed tectonic configurations that allowed the formation of volcanic arcs, back arc basins, transtensional divergent tectonics or the accretion of exotic volcanic terranes. Such record, particularly the extensional phases, can be partially destroyed and obscure by multiple deformational events, the accretion of exotic terranes and strike slip fragmentation along the margin. The tectonic evolution of the northern Andes during the Mesozoic is the result of post Pangea extension followed by the installation of a long-lived Jurassic volcanic arc (209 - 136 ma) that apparently stops between 136 Ma and 110 Ma. The Quebradagrande Complex has been define as a single Lower Cretaceous volcano-sedimentary unit exposed in the western flank of the Central Cordillera of the Colombian Andes that growth after the Late Jurassic to Early Cretaceous magmatic hiatus. The origin of this unit have been related either to an oceanic volcanic arc or a marginal basin environment. The existence of such contrasting models reflect the regional perspective followed in published studies and the paucity of detail analysis of the volcano-sedimentary sequences.We integrate multiple approaches including structural mapping, stratigraphy, geochemistry, U-Pb provenance and geochronology to improve the understanding of this unit and track the earlier phases of accumulation that are mask on the overimposed tectonic history. Our preliminary results suggest the existence of different volcano-sedimentary units that accumulated between 100 Ma and 82 Ma.The older Lower Cretaceous sequences was deposited over Triassic metamorphic continental crust and include a upward basin deepening record characterized by thick fan delta conglomerates, followed by distal turbidites and a syn-sedimentary volcanic record at 100 ma. The other sequence include a 85 - 82 Ma fringing arc that was also formed close to the continental margin or

  7. Rodent community structure and Andes virus infection in sylvan and peridomestic habitats in northwestern Patagonia, Argentina.

    PubMed

    Piudo, Luciana; Monteverde, Martin J; Walker, R Susan; Douglass, Richard J

    2011-03-01

    Modifications of natural habitat in peridomestic rural areas could affect original rodent community composition, diversity, and evenness. In zoonoses such as hantavirus pulmonary syndrome, the presence of a diverse community can dilute the impact of the principal reservoir, reducing risk to humans. The goal of this study was to examine rodent community composition, abundance of Andes virus (ANDV) host (Oligoryzomys longicaudatus), ANDV prevalence, and temporal variability associated with rural peridomestic settings in Patagonia, Argentina. We trapped rodents in peridomestic settings and nearby sylvan areas for 2 years. The numerically dominant species differed between peridomestic and sylvan settings. O. longicaudatus was the most abundant species in peridomestic settings (>50% of individuals). Diversity and evenness in peridomestic settings fluctuated temporally, with an abrupt decline in evenness coinciding with peaks in ANDV prevalence. The probability of finding an ANDV-positive mouse in peridomestic settings was 2.44 times greater than in sylvan habitats. Changes in rodent communities in peridomestic settings may increase the probability for human exposure to ANDV because those settings promote the presence of O. longicaudatus with high ANDV antibody prevalence. High O. longicaudatus relative abundance in an unstable community associated with peridomestic settings may favor intraspecific contact, leading to a higher probability of virus transmission. PMID:21332352

  8. Rodent Community Structure and Andes Virus Infection in Sylvan and Peridomestic Habitats in Northwestern Patagonia, Argentina

    PubMed Central

    Monteverde, Martin J.; Walker, R. Susan; Douglass, Richard J.

    2011-01-01

    Abstract Modifications of natural habitat in peridomestic rural areas could affect original rodent community composition, diversity, and evenness. In zoonoses such as hantavirus pulmonary syndrome, the presence of a diverse community can dilute the impact of the principal reservoir, reducing risk to humans. The goal of this study was to examine rodent community composition, abundance of Andes virus (ANDV) host (Oligoryzomys longicaudatus), ANDV prevalence, and temporal variability associated with rural peridomestic settings in Patagonia, Argentina. We trapped rodents in peridomestic settings and nearby sylvan areas for 2 years. The numerically dominant species differed between peridomestic and sylvan settings. O. longicaudatus was the most abundant species in peridomestic settings (>50% of individuals). Diversity and evenness in peridomestic settings fluctuated temporally, with an abrupt decline in evenness coinciding with peaks in ANDV prevalence. The probability of finding an ANDV-positive mouse in peridomestic settings was 2.44 times greater than in sylvan habitats. Changes in rodent communities in peridomestic settings may increase the probability for human exposure to ANDV because those settings promote the presence of O. longicaudatus with high ANDV antibody prevalence. High O. longicaudatus relative abundance in an unstable community associated with peridomestic settings may favor intraspecific contact, leading to a higher probability of virus transmission. PMID:21332352

  9. Tectonic and climate driven fluctuations in the stratigraphic base level of a Cenozoic continental coal basin, northwestern Andes

    NASA Astrophysics Data System (ADS)

    Silva Tamayo, J. C.; Sierra, G. M.; Correa, L. G.

    2008-12-01

    amalgamation and promoted both, high preservation of geomorphic elements and high diversity of sedimentary facies. This resulted in the most symmetric stratigraphic cycles of the entire Amagá Formation. The final stage of evolution of the Amagá Basin was related to the early stage of development of the late Miocene northwestern Andes tholeitic volcanism (from ˜10 to ˜8 Ma). The extensive thrusting and folding associated to this volcanism reduced the subsidence rates along the basin and thus the accommodation space. This permitted the development of highly aggradational braided rivers and promoted channels amalgamation. Little preservation of low energy facies, poor preservation of the geomorphic elements and a complete obliteration of important swamp deposits (coal beds) within the basin are reflected by the most asymmetric stratigraphic cycles of the whole formation. The presence of greenish/reddish flood plain deposits and Alfisols suggests a dry climate during this depositional stage. The presence of channel sandstones with high contents of volcanic rock fragments supports a dry climate, and suggests an incipient phase of the Combia tholeiitic magmatism present during deposition of the Amagá Formation. The subsequent eastward migration of the NW Andes magmatic arc (after ˜8 Ma) may have produced basin inversion and suppressed deposition along the Amagá Basin.

  10. Climatic and paleoclimatic forcing of erosion in the southern Central Andes and the northwestern Himalaya (Invited)

    NASA Astrophysics Data System (ADS)

    Bookhagen, B.; Strecker, M. R.

    2013-12-01

    The windward flanks of the tectonically active southern Central Andes and the NW Himalaya are characterized by steep climatic, tectonic, and topographic gradients. The first windward topographic rise of these mountain ranges constitutes a significant orographic barrier resulting in high orographic rainfall causing some of the wettest places on Earth. However, the higher-elevation areas of the windward flanks of both regions become progressively drier, until arid conditions are attained in the orogen interiors (i.e., the Altiplano-Puna and Tibet plateaus). Both areas have experienced significant paleoclimatic changes with deeper penetration of moisture into the orogen and thus an orogenward shift of the climate gradient. Some of the world's largest rivers with high sediment loads emerge from these mountain belts, and understanding the relation between climate and erosion is key in predicting mass fluxes, assessing the impacts of climate variability, and long-term climate forcing of erosion on landscape evolution. Here, we quantify the impact of the climatic gradients and their spatial shifts during the late Pleistocene and Holocene. We rely on sedimentary archives, digital topography, and cosmogenic inventories of river sands (10Be) and bedrock-erosion rates (10Be and 26Al) from the Puna Plateau in NW Argentina and the interior of the western Himalaya in NW India. We make three key observations that underline the importance of present-day climatic parameters and paleoclimatic changes on the effiency of surface processes in both areas: (1) First-order spatial erosion patterns follow the climatic gradient and catchment-mean erosion rates vary by three orders of magnitude from the wet mountain fronts to the dry orogen interior. In NW Argentina, our measurements represent the fluvial transport rates and indicate very low fluvial activity in the interior of the Puna Plateau during the Late Pleistocene; (2) the spatial distribution of erosion rates can be explained by a

  11. Paleozoic evolution of active margin basins in the southern Central Andes (northwestern Argentina and northern Chile)

    NASA Astrophysics Data System (ADS)

    Bahlburg, H.; Breitkreuz, C.

    The geodynamic evolution of the Paleozoic continental margin of Gondwana in the region of the southern Central Andes is characterized by the westward progression of orogenic basin formation through time. The Ordovician basin in the northwest Argentinian Cordillera Oriental and Puna originated as an Early Ordovician back-arc basin. The contemporaneous magmatic arc of an east-dipping subduction zone was presumably located in northern Chile. In the back-arc basin, a ca. 3500 meter, fining-up volcaniclastic apron connected to the arc formed during the Arenigian. Increased subsidence in the late Arenigian allowed for the accomodation of large volumes of volcaniclastic turbidites during the Middle Ordovician. Subsidence and sedimentation were caused by the onset of collision between the para-autochthonous Arequipa Massif Terrane (AMT) and the South American margin at the Arenigian-Llanvirnian transition. This led to eastward thrusting of the arc complex over its back-arc basin and, consequently, to its transformation into a marine foreland basin. As a result of thrusting in the west, a flexural bulge formed in the east, leading to uplift and emergence of the Cordillera Oriental shelf during the Guandacol Event at the Arenigian-Llanvirnian transition. The basin fill was folded during the terminal collision of the AMT during the Oclóyic Orogeny (Ashgillian). The folded strata were intruded post-tectonically by the presumably Silurian granitoids of the "Faja Eruptiva de la Puna Oriental." The orogeny led to the formation of the positive area of the Arco Puneño. West of the Arco Puneño, a further marine basin developed during the Early Devonian, the eastern shelf of which occupied the area of the Cordillera Occidental, Depresión Preandina, and Precordillera. The corresponding deep marine turbidite basin was located in the region of the Cordillera de la Costa. Deposition continued until the basin fill was folded in the early Late Carboniferous Toco Orogeny. The basin

  12. Facies and sedimentary environments of the cretaceous La Luna Formation in San Pedro Del Rio section, Venezuelan Andes: A multidisciplinary study

    SciTech Connect

    Boesi, H.T.R.; Lorente, M.A.; Mompart, L.; Murat, B.; Testamarck ); Facon, R. )

    1993-02-01

    Vertical variations in facies and sedimentary environments in an outcrop of the La Luna Formation in the Venezuela Andes were evaluated with an integrated study of sedimentology, micropaleontology, palynology, visual kerogen, organic geochemistry and field geology. Up to now, the La Luna Formation, main hydrocarbon source rock in the Maracaibo Basin, has been considered for calculations of oil generation as an homogeneous interval with similar properties across the basin. However, this study reveals important vertical variations in organic facies and sedimentary environments. The microfacies range from almost pure carbonate (recrystallized) mudstone to almost pure shale, with a varying organic content. An overall upward change from oxic to anoxic environments can be recognized, culminating in a chert-rich interval (Ftanita de Tachira Member). The total organic carbon content is high throughout, with the exception of low to moderate values in the chert. The organic matter is mature to postmature. Phosphatic intervals are also developed, supporting a model of platform-edge upwelling and high organic productivity. The presence of rare volcanic grains suggests comtemporaneous volcanic activity within adjacent areas (Colombian Andes ).

  13. The Eocene turbidities of the Trujillo Formation, Venezuelan Andes

    SciTech Connect

    Ghosh, S.K.; Zambrano, E.

    1996-08-01

    The Trujillo Formation, overlying the Paleocene Cerro Verde and Valle Hondo formations, reveals a turbiditic origin in a lowstand shelf-edge and bathyal setting in two excellent road sections on the Valera-Carache road and many creek sections. The basal outcrop shows well developed fining upward (FU) sequences of proximal channel turbidite and overbank origin (abandonment phase) and minor coarsening upward (CU) sequences representing progradational pulse in overbank areas. The FU (and thinning-upward) sequence, overlying a shale, consists of: (a) basal stacked conglomeratic arenites (probably inner fan channels) with graded beds, imbricate casts and transported shells; (b) a sand/shale alternating unit (channel margin/interchannel) with flame structure, lenticular bedding, infrequent Tb-d Sequence, rippled flats, and rare Planolites; and (c) a dark shale (overbank-interchannel lows) with scarce Chondrites and Scaladtuba traces. The CU sequence consists of thickening-upward heterolithic facies overlain by lenticular stacked pebbly arenites. The upper unit exposed near Puente Gomez is a typical progradational lobe starting with a basal shale, with intraformational diastems and slumped beds, and Tb-d and Tb-e sequences in thin intercalated sandstones; a heterolithic facies with flute/groove casts, Planolites, Thalassinoides and Neonereites occurs between the shale and a thick cross-stratified sandstone at the top. This CU lobe sequence is discordantly(?) overlain by a thin wedge of massive bedded pebbly sandstones of Middle Eocene(?) Misoa Formation. Unlike the southwesterly sourced subsurface turbidites, those in this area were probably sourced from both the south and north, though locally the southern source might have been more important.

  14. ASTER Andes

    NASA Technical Reports Server (NTRS)

    2000-01-01

    In this image of the Andes along the Chile-Bolivia border, the visible and infrared data have been computer enhanced to exaggerate the color differences of the different materials. The scene is dominated by the Pampa Luxsar lava complex, occupying the upper right two-thirds of the scene. Lava flows are distributed around remnants of large dissected cones, the largest of which is Cerro Luxsar. On the middle left edge of the image are the Olca and Parumastrato volcanoes, which appear in blue due to a lack of vegetation (colored red in this composite). This image covers an area 60 kilometers (37 miles) wide and 60 kilometers (37 miles) long in three bands of the reflected visible and infrared wavelength region. It was acquired on April 7, 2000.

    The image is located at 21 degrees south latitude, 68.3 degrees west longitude.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping and monitoring dynamic conditions and temporal change. Examples of applications include monitoring glacial

  15. Solar and Volcanic Modulation of Little Ice Age Climate in the Tropical Andes, Venezuela

    NASA Astrophysics Data System (ADS)

    Polissar, P. J.; Abbott, M. B.; Wolfe, A. P.; Rull, V.; Bezada, M.

    2004-12-01

    The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here, we report a 1500-year reconstruction of climate history in the Venezuelan Andes using lake sediment records from four sites. This reconstruction is based upon accelerator mass spectrometry (AMS) radiocarbon and Pb-210 dating, sedimentology, magnetic susceptibility, geochemistry, pollen and stable isotope (C, N) measurements. In the Laguna Mucubaji watershed four distinct glacial advances occurred between 1250 and 1810 A.D. The earliest advance began during an extended period of higher global volcanic activity. The subsequent three advances were coincident with minima in solar activity (reconstructed from Be-10 and C-14 records). The Mucubají glacial activity in the Venezuelan Andes coincides with other records of Little Ice Age (LIA) glacial advances in S. America. Comparison of modern glacier equilibrium line altitudes (ELAs) in Venezuela with the Mucubaji LIA glacier ELA indicates an ELA depression of at least 300 m. Both a decline in temperature and increase in precipitation are required to explain the ELA depression. The precipitation increase is supported by increased catchment erosion recorded in L. Blanca sediments. Pollen records from two sites in the Venezuelan Andes also indicate wetter and colder conditions during the LIA.

  16. Aftermath of Venezuelan flood disaster

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    One month after several rounds of devastating floods and mudslides waterlogged parts of Venezuela in December and January, the country and government are trying to come to grips with the damage and begin reconstruction efforts. They are also trying to limit potential health risks that can arise following natural disasters. Epidemics, however, rarely occur following a disaster, according to Jean-Luc Poncelet, a doctor with the Pan American Health Organization. Between 25,000 and 50,000 people in Venezuela were killed, and about 150,000 displaced, according to local and international aid authorities. In addition,Venezuelan national authorities have declared part of the Port of La Guaira as a dangerous chemical zone because of ruptured containers of dangerous chemicals, hundreds of kilometers of the Caribbean coast have been closed to fishing and swimming because of contaminated runoff from the floods, roads remain blocked, and the lack of potable water is a key concern.

  17. Lithospheric scale model of Merida Andes, Venezuela (GIAME Project)

    NASA Astrophysics Data System (ADS)

    Schmitz, M.; Orihuela, N. D.; Klarica, S.; Gil, E.; Levander, A.; Audemard, F. A.; Mazuera, F.; Avila, J.

    2013-05-01

    Merida Andes (MA) is one of the most important orogenic belt in Venezuela and represents the northern culmination of South America Andes. During the last 60 years, several models have been proposed to explain the shallow and deep structure, using different geological, geophysical, seismological, geochemical and petrologic concepts; nevertheless, most of them have applied local observation windows, and do not represent the major structure of MA. Therefore, a multidisciplinary research group, coordinated by FUNVISIS, in close cooperation with UCV, ULA and PDVSA, is proposed in order to get the outlined goals in the project entitled GIAME ("Geociencia Integral de los Andes de MErida") was established, which aims to generate a lithospheric scale model and the development of a temporal dynamic model for the MA. As a base for lithospheric investigations of the Merida Andes, we are proposing three wide angle seismic profiles across the orogen on three representative sites, in order to determine the inner structure and its relation with the orogen's gravimetric root. To the date, there are no seismic studies at lithospheric scale which cross MA. The wide angle seismic will be complemented with the re-processing and re-interpretation of existing reflection seismic data, which will allow to establish a relationship between MA and its associated flexural basins (Maracaibo and Barinas-Apure basins). Depending on the results of the VENCORP Project (VENezuelan COntinental Reflection Profiling), which might show some reliable results about crustal features and Moho reflectors along three long seismic profiles at Caribbean Moutain system, a reflection seismic profile across the central portion of MA is proposed. Additional tasks, consisting in MA quaternary deformation studies, using research methods like neotectonics and paleoseismology, georadar, numerical modeling, cinematic GPS, SAR interferometry, thermocronology, detailed studies on regional geology, flexural modeling

  18. Andes Altiplano, South America

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Looking westward over the Andes Altiplano, (14.S, 72.5W) this panoramic view shows details of the deep river gorges cut into the mountains as they rose to their present heights of over 10,000 to 13,000 ft. over the past 20 million years. The eastern slopes of the Andes are heavily forested and form the headwaters of the Amazon River drainage basin. Smoke from logging or land clearing operations can be seen in the lower river valleys.

  19. New polyisoprenylated benzophenones from Venezuelan propolis.

    PubMed

    Trusheva, Boryana; Popova, Milena; Naydenski, Hristo; Tsvetkova, Iva; Gregorio Rodriguez, Jose; Bankova, Vassya

    2004-12-01

    Two new polyisoprenylated benzophenones, 18-ethyloxy-17-hydroxy-17,18-dihydroscrobiculatone A and 18-ethyloxy-17-hydroxy-17,18-dihydroscrobiculatone B, together with the known scrobiculatones A and B, were isolated from Venezuelan propolis. The scrobiculatones A and B showed significant antibacterial activity and moderate toxicity to Artemia salina nauplii.

  20. Solar modulation of Little Ice Age climate in the tropical Andes.

    PubMed

    Polissar, P J; Abbott, M B; Wolfe, A P; Bezada, M; Rull, V; Bradley, R S

    2006-06-13

    The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here we report a 1,500-year reconstruction of climate history and glaciation in the Venezuelan Andes using lake sediments. Four glacial advances occurred between anno Domini (A.D.) 1250 and 1810, coincident with solar-activity minima. Temperature declines of -3.2 +/- 1.4 degrees C and precipitation increases of approximately 20% are required to produce the observed glacial responses. These results highlight the sensitivity of high-altitude tropical regions to relatively small changes in radiative forcing, implying even greater probable responses to future anthropogenic forcing.

  1. Solar modulation of Little Ice Age climate in the tropical Andes

    PubMed Central

    Polissar, P. J.; Abbott, M. B.; Wolfe, A. P.; Bezada, M.; Rull, V.; Bradley, R. S.

    2006-01-01

    The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here we report a 1,500-year reconstruction of climate history and glaciation in the Venezuelan Andes using lake sediments. Four glacial advances occurred between anno Domini (A.D.) 1250 and 1810, coincident with solar-activity minima. Temperature declines of −3.2 ± 1.4°C and precipitation increases of ≈20% are required to produce the observed glacial responses. These results highlight the sensitivity of high-altitude tropical regions to relatively small changes in radiative forcing, implying even greater probable responses to future anthropogenic forcing. PMID:16740660

  2. Venezuelan political debate focuses on Pdvsa

    SciTech Connect

    Not Available

    1992-09-14

    This paper reports that another political firestorm has flared over Venezuelan petroleum sector investment. Statements by Venezuela's President Carlos Andres Perez who has provoked a new political debate over oil affairs in Venezuela. Commenting on Pdvsa's overseas interests, it has been ordered that the state oil company to sell part of its shares in Citgo Petroleum Corp., Tulsa, and Ruhr Oel GmbH, a joint venture with Veba Oel AG, Gelsenkirchen.

  3. Late Quaternary deglacial history of the Mérida Andes, Venezuela

    NASA Astrophysics Data System (ADS)

    Stansell, Nathan D.; Abbott, Mark B.; Polissar, Pratigya J.; Wolfe, Alexander P.; Bezada, Maximiliano; Rull, Valentí

    2005-10-01

    Radiocarbon-dated sediment cores from seven lakes and two bogs spanning the Cordillera de Mérida in the Venezuelan Andes were used to identify and date the regional history of late Pleistocene and Holocene glacial activity. Coring sites were selected at different elevations across a pronounced rain shadow from southeast (wet) to northwest (dry). Sediment lithostratigraphy and magnetic susceptibility, in conjunction with AMS radiocarbon dates on macrofossils and charcoal, were used to constrain deglaciation. The local expression of the Last Glacial Maximum occurred between 22 750 and 19 960 cal. yr BP. On the wetter southeastern side of the Cordillera de Mérida, glaciers had significantly retreated by 15 700 cal. yr BP, followed by several minor glacial advances and retreats between 14 850 and 13 830 cal. yr BP. At least one major glacial readvance occurred between 13 830 and 10 000 cal. yrBP in the wetter southeastern sector of the region. The drier northwest side of the Cordillera de Mérida records initial glacial retreat by 14240cal.yrBP. Multiple sites on both sides of the Mérida Andes record a further phase of extensive deglaciation approximately 10000cal.yrBP. However, the north-northwest facing Mucubají catchment remained partially glaciated until ca. 6000cal.yrBP. Deglacial ages from the Venezuelan Andes are consistently younger than those reported from the Southern Hemisphere Andes, suggesting an inter-hemispheric deglacial lag in the northern tropics of the order of two thousand years.

  4. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Encephalomyelitis Vaccine, Venezuelan... REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine... established as pure, safe, and immunogenic shall be used for preparing seeds for vaccine production....

  5. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Encephalomyelitis Vaccine, Venezuelan... REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine... established as pure, safe, and immunogenic shall be used for preparing seeds for vaccine production....

  6. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Encephalomyelitis Vaccine, Venezuelan... REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine... established as pure, safe, and immunogenic shall be used for preparing seeds for vaccine production....

  7. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Encephalomyelitis Vaccine, Venezuelan... REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine... established as pure, safe, and immunogenic shall be used for preparing seeds for vaccine production....

  8. Seismological Parameters in the Northern Andes, Venezuela

    NASA Astrophysics Data System (ADS)

    Sobiesiak, M.; Palme de Osechas, C.; Choy, J. E.; Morandi S., M. T.; Campo, M.; Granado Ruiz, C.

    2001-12-01

    Venezuelas tectonic setting as part of the plate boundary between the Caribbean and the South American plate causes two major seismologically active fault systems: the roughly west - east trending strike slip fault system along the coast with numerous sub-parallel faults and the Bocono fault system, which dominates the Venezuelan southwest - northeast striking Andes. The main Bocono fault reaches a total length of about 500 km and has a width of approximately 100 km between the southern and northern baseline of the mountain slopes which are marked by inverse faults. This is believed to be due to strain partitioning, a concept which seems to apply as well to the Bocono fault system. The whole fault system is characterized by a high seismicity rate of small scale and intermediate event magnitudes ranging from 1.5 to 6.3 in the last fifty years. In this study we would like to present an investigation on 39 focal mechanism solutions and a b-value mapping of the Andean region with the main goal to throw light on the stess and strain situation. For recompiling the focal memchanisms calculated from first motion polarities, various sources had to been used: seismograms from stations of the local and regional networks of the Seismological Center of ULA, the national seismic network operated by FUNVISIS, the seismic network Lago Maracaibo of PDVSA and the local seismic network of DESURCA. For the b-value mapping we used the two catalogues of ULA and DESURCA of which the last one registered more than 6500 events from 1994 to 1999. The set of focal mechanism solutions studied showed normal, strike slip, and reverse faulting mechanisms concentrated in distinct areas of the Bocono fault system and thus resulting in a zonation also supported by the determinations of the azimuths of the maximum horizontal stress SHmax. This hypothesis of the zonation of the Andes region is strongly supported by the results of the b-value mapping. The zonation as seen in the varying major stress

  9. Morphogenesis of Venezuelan Equine Encephalomyelitis Virus

    PubMed Central

    Bykovsky, A. F.; Yershov, F. I.; Zhdanov, V. M.

    1969-01-01

    Morphogenesis of Venezuelan equine encephalomyelitis virus was studied by means of electron microscopy. Virus-specific structures (factories, viroplasts) were found at early stages of infection; these structures were composed of fibrillar and cylindrical formations, aggregates of ribosomes, and viral nucleoids. The latter emerged from fibrillar and cylindrical structures. Aggregates of viral nucleoids were found in the cytoplasm and occasionally in the nuclei of virus-infected cells. Viral envelopes and mature virions were formed on the cell membranes and on the membranes of intracellular vacuoles. Anomalous forms of virions (both polygenomic and oligogenomic) were observed. Images PMID:5823233

  10. Isonymy structure of four Venezuelan states.

    PubMed

    Rodríguez-Larralde, A; Barrai, I; Alfonzo, J C

    1993-01-01

    The isonymy structure of four Venezuelan States-Falcón, Mérida, Nueva Esparta and Yaracuy-was studied using the surnames of the Venezuelan register of electors updated in 1984. The surname distributions of 155 counties were obtained and, for each county, estimates of consanguinity due to random isonymy and Fisher's alpha were calculated. It was shown that for large sample sizes the inverse of Fisher's alpha is identical to the unbiased estimate of within-population random isonymy. A three-dimensional isometric surface plot was obtained for each State, based on the counties' random isonymy estimates. The highest estimates of random consanguinity were found in the States of Nueva Esparta and Mérida, while the lowest were found in Yaracuy. Other microdifferentiation indicators from the same data gave similar results, and an interpretation was attempted, based on the particular economic and geographic characteristics of each State. Four different genetic distances between all possible pairs of counties were calculated within States; geographic distance shows the highest correlations with random isonymy and Euclidean distance, with the exception of the State of Nueva Esparta, where there is no correlation between geographic distance and random isonymy. It was possible to group counties in clusters, from dendrograms based on Euclidean distance. Isonymy clustering was also consistent with socioeconomic and geographic characteristics of the counties. PMID:8447658

  11. Volatile constituents of the leaves of Munnozia senecionidis from the Venezuelan Andes.

    PubMed

    Lara, Joel; Rojas, Luis B; Usubillaga, Alfredo; Carmona, Juan

    2009-07-01

    The essential oil of Munnozia senecionidis Benth. (Asteraceae), obtained by hydrodistillation, was analyzed by GC-MS. Twenty compounds were identified, accounting for 93.9% of the oil. The most abundant components were caryophyllene oxide (19.9%), trans-nerolidol (12.1%), epi-alpha-cadinol (9.4%) and hexadecanoic acid (8.8%).

  12. Chemical composition and larvicidal activity of Eugenia triquetra essential oil from Venezuelan Andes.

    PubMed

    Mora, Flor D; Avila, Jorge L; Rojas, Luis B; Ramírez, Rosslyn; Usubillaga, Alfredo; Segnini, Samuel; Carmona, Juan; Silva, Bladimiro

    2010-06-01

    The chemical constituents of the essential oil obtained by hydrodistillation of the leaves of Eugenia triquetra O. Berg, collected in Táchira State, Venezuela, were identified by GC-MS analysis. Twenty-six components, which made up 88.5% of the oil, were identified. The major constituents were linalool (17.5%), limonene (16.9%), alpha-pinene (11.6%), beta-pinene (8.7%), and p-cymene (3.7%). The essential oil was tested against third-instar larvae of Aedes aegypti, showing a LC50 value of 64.8 +/- 5.6 ppm.

  13. Chemical composition and antibacterial activity of the essential oil of Cordia verbenacea from the Venezuelan Andes.

    PubMed

    Meccia, Gina; Rojas, Luis B; Velasco, Judith; Díaz, Tulia; Usubillaga, Alfredo; Arzola, Juan Carmona; Ramos, Sulymar

    2009-08-01

    The essential oil of Cordia verbenacea D.C. (Boraginaceae) that grows in Mérida-Venezuela was obtained by hydrodistillation from the aerial parts of the plant, yielding 0.21%. The oil was analyzed by GC-FID and GC-MS. Thirty one components which made up 94.3% of the oil were identified. The most abundant constituents found were: tricyclene (23.9%), bicyclogermacrene (11.7%), germacrene D (9.9%) and beta-caryophyllene (8.2%). Antibacterial activity determination was carried out according to the disc diffusion assay. Activity against Gram-positive bacteria Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212, at a minimal inhibitory concentration (MIC) of 170 microg/mL and 200 microg/mL, was found.

  14. Petroleum systems of the Burgua Depression, Tachira and Apure states, Venezuelan Andes

    SciTech Connect

    Ostos, M.; Yoris, F.; Callejon, A.

    1996-08-01

    The Burgua Depression (southeast extension of the Tachira Depression) underwent a severe subsidence during the Andean orogeny. Its tectonosedimentary evolution was controlled by Paleozoic discontinuities. The sedimentary sequence contains Jurassic/Lower Cretaceous syn-rifting transgressive rocks, synDeformational Paleocene/Eocene and Neogene rocks. Deformation is diachronic from SE (Oligocene) to NW (Pleistocene). From oil-rock correlation data, Navay and Los Cuervos samples render excellent potential source rocks. The analyses indicate a marine algal-bacterial organic matter source for Navay and higher plants for Los Cuervos, which plot as moderate yield type II kerogen and low yield type II-III, respectively. Although, the samples are immature (0.50-0.55% R6), ID modelling (BasinMod) suggests that they reached maturation during the Andean orogeny. Oil seeps correlate with Navay and Los Cuervos and were expelled at the peak of oil generation (0.85-0.90% R{sub o}). These source rocks define the Navay-K/T(!) and Los Cuervos-K/T(!) petroleum systems. Potential clastic and carbonatic reservoirs were identified in surface and wells. The Guafita Formation is the regional seal, never extending northward of the Brujas High. Modelling indicates that migration started during late Pliocene and took place northward and south/southeastward of the Andean foredeep.

  15. Experimental Study of Soil Organic Matter Loss From Cultivated Field Plots In The Venezuelan Andes.

    NASA Astrophysics Data System (ADS)

    Bellanger, B.; Huon, S.; Velasquez, F.; Vallès, V.; Girardin A, C.; Mariotti, A. B.

    The question of discriminating sources of organic matter in suspended particles of stream flows can be addressed by using total organic carbon (TOC) concentration and stable isotope (13C, 15N) measurements when constant fluxes of organic matter supply can be assumed. However, little is known on the dynamics of organic matter release during soil erosion and on the temporal stability of its isotopic signature. In this study, we have monitored soil organic carbon loss and water runoff using natural rainfall events on three experimental field plots with different vegetation cover (bare soil, maize and coffee fields), set up on natural slopes of a tropical mountainous watershed in NW Venezuela (09°13'32'' ­ 09°10'00''N, 70°13'49'' ­ 70°18'34''W). Runoff and soil loss are markedly superior for the bare field plot than for the coffee field plot: by a factor 15 ­ 36, respectively, for the five-month experiment, and by a factor 30 ­ 120, respectively, during a single rainfall event experiment. Since runoff and soil organic matter loss are closely linked during most of the flow (at the time scales of this study), TOC concentration in suspended matter is constant. Furthermore, stable isotope compositions reflect those of top-soil organic matter from which they originate.

  16. [Colombian migration to the Venezuelan agrarian sector: a binational context].

    PubMed

    Mora, J; Gomez, A

    1980-01-01

    The authors attempt to determine the reasons for the chronic national labor shortage in the Venezuelan agrarian sector and for the large-scale emigration of Colombians to work in Venezuelan agriculture. The income of agricultural wage earners and the conditions of labor force reproduction in Venezuela are discussed as factors contributing to the labor shortage. With reference to Colombia, the rapid growth of international commerce and the policy of limiting wages are suggested as factors which contribute to emigration

  17. Venezuelan equine encephalitis virus, southern Mexico.

    PubMed

    Estrada-Franco, José G; Navarro-Lopez, Roberto; Freier, Jerome E; Cordova, Dionicio; Clements, Tamara; Moncayo, Abelardo; Kang, Wenli; Gomez-Hernandez, Carlos; Rodriguez-Dominguez, Gabriela; Ludwig, George V; Weaver, Scott C

    2004-12-01

    Equine epizootics of Venezuelan equine encephalitis (VEE) occurred in the southern Mexican states of Chiapas in 1993 and Oaxaca in 1996. To assess the impact of continuing circulation of VEE virus (VEEV) on human and animal populations, serologic and viral isolation studies were conducted in 2000 to 2001 in Chiapas State. Human serosurveys and risk analyses indicated that long-term endemic transmission of VEEV occurred among villages with seroprevalence levels of 18% to 75% and that medical personnel had a high risk for VEEV exposure. Seroprevalence in wild animals suggested cotton rats as possible reservoir hosts in the region. Virus isolations from sentinel animals and genetic characterizations of these strains indicated continuing circulation of a subtype IE genotype, which was isolated from equines during the recent VEE outbreaks. These data indicate long-term enzootic and endemic VEEV circulation in the region and continued risk for disease in equines and humans. PMID:15663847

  18. Endemic Venezuelan Equine Encephalitis in Northern Peru

    PubMed Central

    Aguilar, Patricia V.; Greene, Ivorlyne P.; Coffey, Lark L.; Medina, Gladys; Moncayo, Abelardo C.; Anishchenko, Michael; Ludwig, George V.; Turell, Michael J.; O’Guinn, Monica L.; Lee, John; Tesh, Robert B.; Watts, Douglas M.; Russell, Kevin L.; Hice, Christine; Yanoviak, Stephen; Morrison, Amy C.; Klein, Terry A.; Dohm, David J.; Guzman, Hilda; Travassos da Rosa, Amelia P.A.; Guevara, Carolina; Kochel, Tadeusz; Olson, James; Cabezas, Cesar

    2004-01-01

    Since Venezuelan equine encephalitis virus (VEEV) was isolated in Peru in 1942, >70 isolates have been obtained from mosquitoes, humans, and sylvatic mammals primarily in the Amazon region. To investigate genetic relationships among the Peru VEEV isolates and between the Peru isolates and other VEEV strains, a fragment of the PE2 gene was amplified and analyzed by single-stranded conformation polymorphism. Representatives of seven genotypes underwent sequencing and phylogenetic analysis. The results identified four VEE complex lineages that cocirculate in the Amazon region: subtypes ID (Panama and Colombia/Venezuela genotypes), IIIC, and a new, proposed subtype IIID, which was isolated from a febrile human, mosquitoes, and spiny rats. Both ID lineages and the IIID subtype are associated with febrile human illness. Most of the subtype ID isolates belonged to the Panama genotype, but the Colombia/Venezuela genotype, which is phylogenetically related to epizootic strains, also continues to circulate in the Amazon basin. PMID:15200823

  19. Endemic Venezuelan equine encephalitis in northern Peru.

    PubMed

    Aguilar, Patricia V; Greene, Ivorlyne P; Coffey, Lark L; Medina, Gladys; Moncayo, Abelardo C; Anishchenko, Michael; Ludwig, George V; Turell, Michael J; O'Guinn, Monica L; Lee, John; Tesh, Robert B; Watts, Douglas M; Russell, Kevin L; Hice, Christine; Yanoviak, Stephen; Morrison, Amy C; Klein, Terry A; Dohm, David J; Guzman, Hilda; Travassos da Rosa, Amelia P A; Guevara, Carolina; Kochel, Tadeusz; Olson, James; Cabezas, Cesar; Weaver, Scott C

    2004-05-01

    Since Venezuelan equine encephalitis virus (VEEV) was isolated in Peru in 1942, >70 isolates have been obtained from mosquitoes, humans, and sylvatic mammals primarily in the Amazon region. To investigate genetic relationships among the Peru VEEV isolates and between the Peru isolates and other VEEV strains, a fragment of the PE2 gene was amplified and analyzed by single-stranded conformation polymorphism. Representatives of seven genotypes underwent sequencing and phylogenetic analysis. The results identified four VEE complex lineages that cocirculate in the Amazon region: subtypes ID (Panama and Colombia/Venezuela genotypes), IIIC, and a new, proposed subtype IIID, which was isolated from a febrile human, mosquitoes, and spiny rats. Both ID lineages and the IIID subtype are associated with febrile human illness. Most of the subtype ID isolates belonged to the Panama genotype, but the Colombia/Venezuela genotype, which is phylogenetically related to epizootic strains, also continues to circulate in the Amazon basin.

  20. Genetic Diversity of Venezuelan Alphaviruses and Circulation of a Venezuelan Equine Encephalitis Virus Subtype IAB Strain During an Interepizootic Period

    PubMed Central

    Medina, Gladys; Garzaro, Domingo J.; Barrios, Miguel; Auguste, Albert J.; Weaver, Scott C.; Pujol, Flor H.

    2015-01-01

    Several species of alphaviruses have been previously described in the Americas, some of which are associated with encephalitis and others are associated with arthralgia. Venezuelan equine encephalitis virus (VEEV) and eastern equine encephalitis virus (EEEV) are endemic to Venezuela, with the former being responsible for major outbreaks of severe and often fatal disease in animals and humans. The aim of this study was to analyze the genetic diversity of Venezuelan alphaviruses isolated during two decades (1973–1999) of surveillance in northern Venezuela. Phylogenetic analysis indicated the circulation of a VEEV subtype IAB strain 8 years after the last reported outbreak. Thirteen strains within two subclades of South American lineage III of EEEV were also found in Venezuela. Considerable genetic variability was observed among Venezuelan Una virus strains, which were widely distributed among the clades. The first Venezuelan Mayaro sequence was also characterized. PMID:25940191

  1. 78 FR 24228 - Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Final Comprehensive Conservation Plan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-24

    ... review and comment following the announcement in the Federal Register on October 29, 2012 ] (77 FR 65574... Fish and Wildlife Service Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Final... Complex (Complex), which includes Lake Andes NWR, Karl E. Mundt NWR, and Lake Andes Wetland...

  2. 77 FR 65574 - Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Draft Comprehensive Conservation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-29

    ... Complex. We started this process through a notice in the Federal Register (72 FR 27328; May, 15, 2007... Fish and Wildlife Service Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Draft... assessment (EA) for the Lake Andes National Wildlife Refuge Complex (Complex), which includes Lake Andes...

  3. Jotï ecogony, Venezuelan Amazon

    NASA Astrophysics Data System (ADS)

    Zent, Egleé L.

    2013-03-01

    The current environmental crisis permeates the discourse and concerns of people all over the world. Consideration of diverse environmental ethics showing the alternative ways in which people conceptualize and relate to nature and natural resources are critical for bringing about more sustainable human behaviors. After a brief review of Western historical notions of nature, this work explores the ecogony, or causal reasons, that trigger the behavior of the Jotï, an Amerindian people of the Venezuelan Amazon, with other entities and the forest that they inhabit. The analysis presented synthesizes 15 years of transdisciplinary ethno-ecological research comprising quantitative and qualitative methods (collection of herbarium voucher specimens, floristic inventories in forest plots, structured interviews focused on plot vegetation, semi-structured interviews of life-histories, participant observation, time allocation studies, food resource accounting, focal person following observations, garden crop inventories and censuses, mapping of wild resource harvest locations, among others). Jotï pragmatic and ideological tenets generate a distinctive environmental ethics based on ecogonic nodes. Notions of interdependence, humanity and person are articulated on a daily basis through several dynamics: (1) hyper-awareness of all living things’ dependence on each other and other elements of the biophysical environment at macroscales and microscales, (2) the construction of human spiritual, conscious, physical and agentive constituents from a variety of diverse botanical and zoological species and mineral components of their homeland, and (3) an understanding of the aggregate surroundings, including a significant portion of the biotic and abiotic components, as potential subjects with awareness, creativity and moral stances. This condition of interdependence confers rights and duties on all the parts. Jotï horizontal communications with and among life-forms sustain their

  4. Charles Darwin in the Andes

    ERIC Educational Resources Information Center

    Bizzo, Nelio; Bizzo, Luis Eduardo Maestrelli

    2006-01-01

    Considering geological time as an important epistemological obstacle to the construction of ideas on biological evolution, a study was carried out on the so-called "Darwin Papers". The conclusion was that Charles Darwin's excursion in the Andes during March-April 1835 was a crucial step in this regard. An expedition was carried out in March-April…

  5. Transcultural Diabetes Nutrition Algorithm (tDNA): Venezuelan Application

    PubMed Central

    Nieto-Martínez, Ramfis; Hamdy, Osama; Marante, Daniel; Inés Marulanda, María; Marchetti, Albert; Hegazi, Refaat A.; Mechanick, Jeffrey I.

    2014-01-01

    Medical nutrition therapy (MNT) is a necessary component of comprehensive type 2 diabetes (T2D) management, but optimal outcomes require culturally-sensitive implementation. Accordingly, international experts created an evidence-based transcultural diabetes nutrition algorithm (tDNA) to improve understanding of MNT and to foster portability of current guidelines to various dysglycemic populations worldwide. This report details the development of tDNA-Venezuelan via analysis of region-specific cardiovascular disease (CVD) risk factors, lifestyles, anthropometrics, and resultant tDNA algorithmic modifications. Specific recommendations include: screening for prediabetes (for biochemical monitoring and lifestyle counseling); detecting obesity using Latin American cutoffs for waist circumference and Venezuelan cutoffs for BMI; prescribing MNT to people with prediabetes, T2D, or high CVD risk; specifying control goals in prediabetes and T2D; and describing regional differences in prevalence of CVD risk and lifestyle. Venezuelan deliberations involved evaluating typical food-based eating patterns, correcting improper dietary habits through adaptation of the Mediterranean diet with local foods, developing local recommendations for physical activity, avoiding stigmatizing obesity as a cosmetic problem, avoiding misuse of insulin and metformin, circumscribing bariatric surgery to appropriate indications, and using integrated health service networks to implement tDNA. Finally, further research, national surveys, and validation protocols focusing on CVD risk reduction in Venezuelan populations are necessary. PMID:24699193

  6. [Venezuelan equine encephalitis: state-of-the-art].

    PubMed

    Anishchenko, M; Alekseev, V V; Lipnitskiĭ, A V

    2006-01-01

    The paper provides the currently available data on the global prevalence of Venezuelan equine encephalitis (VEE), its epidemiology, clinical picture, and specific prevention in human beings. It also discussed the problem of potential use of the causative agent of VEE as a subject of bioterrorism.

  7. Brokerage, Political Opportunity, and Protest in Venezuelan Higher Education Reform

    ERIC Educational Resources Information Center

    Storm, Elliot

    2015-01-01

    This paper explores two episodes of contention in the ongoing conflict between the Venezuelan government and the country's autonomous universities. In August 2009, Venezuela's National Assembly approved and implemented the controversial Organic Education Law. Sixteen months later, the Assembly approved the similarly polarizing Law of University…

  8. Tectonics of the central Andes

    NASA Technical Reports Server (NTRS)

    Bloom, Arthur L.; Isacks, Bryan L.; Fielding, Eric J.; Fox, Andrew N.; Gubbels, Timothy L.

    1989-01-01

    Acquisition of nearly complete coverage of Thematic Mapper data for the central Andes between about 15 to 34 degrees S has stimulated a comprehensive and unprecedented study of the interaction of tectonics and climate in a young and actively developing major continental mountain belt. The current state of the synoptic mapping of key physiographic, tectonic, and climatic indicators of the dynamics of the mountain/climate system are briefly reviewed.

  9. Socialized medicine or state-ruled medicine: the Venezuelan dilemma.

    PubMed

    Morgado, P J

    1989-07-01

    The economic crisis in which Venezuela is living, caused by the fall in oil prices, has forced the government to reorganize its medical services. A central administrative organ, the National Health Service, has been created. It seeks to develop a social medicine directed at the less favored classes of the population. Notwithstanding the continuously rising costs of private medicine, which, until now, the government has permitted without restrictions, the shadow of government intervention looms ominously over private practice, where subemployment of doctors already exists, along with the growing tendencies of insurance companies to impose economic conditions. The Venezuelan Medical Federation, which, by law, groups all Venezuelan doctors, has began a battle on two main fronts: against the State intervention and against the insurance companies who hope to benefit at the expense of the already underpaid doctors.

  10. Experimental infection of birds with epidemic Venezuelan encephalitis virus.

    PubMed

    Bowen, G S; McLean, R G

    1977-07-01

    Sixty-three birds representing 13 species were inoculated with a strain of epidemic Venezuelan encephalitis (VE) virus from the 1971 Texas outbreak. More than 95% of the birds became infected. Mortality which could be attributed to infection with VE virus was very low. Viremia persisted 2-6 days. Peak viremia levels ranged from 10(3.2) to 10(8.2) suckling mouse intracranial 50% lethal doses per milliliter (SMICLD50/ml). Blood virus levels were highest in juvenile Louisiana Herones, adult Robins and adult Mockingbirds and were lowest in juvenile Common Egrets. Most bird species had blood virus levels about 10(5) SMICLD50/ml (high vector infection potential) for 2-3 days. Neutralizing antibody response was more uniform and frequent in herons (95%) than in passerines (56%). The role of birds in the epidemiology of Venezuelan is discussed.

  11. Western Slope of Andes, Peru

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Along the western flank of the Andes, 400 km SE of Lima Peru, erosion has carved the mountain slopes into long, narrow serpentine ridges. The gently-sloping sediments have been turned into a plate of worms wiggling their way downhill to the ocean.

    The image was acquired September 28, 2004, covers an area of 38 x 31.6 km, and is located near 14.7 degrees south latitude, 74.5 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  12. Grenvillian remnants in the Northern Andes: Rodinian and Phanerozoic paleogeographic perspectives

    NASA Astrophysics Data System (ADS)

    Cardona, A.; Chew, D.; Valencia, V. A.; Bayona, G.; Mišković, A.; Ibañez-Mejía, M.

    2010-01-01

    Grenvillian crust is encountered in several basement inliers in the northern Andes of Colombia, Ecuador and Peru and is also represented as a major detrital or inherited component within Neoproterozoic to Paleozoic sedimentary and magmatic rocks. This review of the tectonic and geochronological record of the Grenvillian belt in the northern Andes suggests that these crustal segments probably formed on an active continental margin in which associated arc and back-arc magmatism evolved from ca. 1.25 to 1.16 Ga, possibly extending to as young as 1.08 Ga. The lithostratigraphic and tectonic history of the Grenvillian belt in the northern Andes differs from that of the Sunsas belt on the southwest Amazonian Craton and from the Grenvillian belt of Eastern Laurentia. It is considered that this belt, along with similar terranes of Grenvillian age in Middle America and Mexico define a separate composite orogen which formed on the northwestern margin of the Amazonian Craton. Microcontinent accretion and interaction with the Sveconorwegian province on Baltica is a feasible tectonic scenario, in line with recent paleogeographic reconstructions of the Rodinian supercontinent. Although Phanerozoic tectonics may have redistributed some of these terranes, they are still viewed as para-autocthonous domains that remained in proximity to the margin of Amazonia. Paleogeographic data derived from Phanerozoic rocks suggest that some of the Colombian Grenvillian fragments were connected to northernmost Peru and Ecuador until the Mesozoic, whereas the Mexican terranes where attached to the Colombian margin until Pangea fragmentation in Late Triassic times.

  13. Andes

    Atmospheric Science Data Center

    2013-04-18

    ... Peru, the northern portion of Chile, and the western part of Bolivia, which intersect near the inward "bend" in the coastline. Lake ... whose coastline forms part of the border between Peru and Bolivia, is prominently featured. At an altitude of 12,500 feet, it is said to ...

  14. Andes

    Atmospheric Science Data Center

    2013-04-18

    ... provide a striking demonstration of the power of water erosion. This image pair was acquired by the Multi-angle Imaging ... with the red filter placed over your left eye. Two main erosion formations can be seen. The one above image center is carved by the Rio ...

  15. By analogy with late paleozoic orogeny in the Venezuelan Andes, Maracaibo Basin is en route to a granitic event

    SciTech Connect

    Shagam, R.; Giegengack, R.F.; Lutz, T.M.

    1985-01-01

    Postulated stages of orogeny in a continental crustal setting are:- 1. Stresses of plate convergence lead to block uplift and complementary basin subsidence. The basin fills with 12-14 km of illite-rich flysch (1km/3Ma). This about doubles the thickness of K-rich sial. 2. In situ heating of the flysch by radioactive decay provides a thermal gradient of c.35/sup 0/C/km and it is metamorphosed (pre-deformation) to greenschists facies. 3. After maximum crustal subsidence continued compression results in updoming of crust and overlying flysch. Cannibalism of flysch, cooling and mild subsidence follow; autometamorphism declines. 4. Thin deltaic-marine deposits complete basin fill over the meta-flysch. The unconformity (a span of only 5-10 Ma) is of minor import. 5. Resetting of the thermal profile of the depressed crust lags far behind that in the flysch. Parallels to the above in the Maracalbo basin fill are: -thickness (approx.11km), nature (flysch abounds), rate of deposition (c.1km/3-4Ma), thermal gradient (c.33/sup 0/C/km) and overall tesselar shape. Presence of impermeable strata in the Maracaibo Basin suggests that large-scale fluid convection is inhibited; conductive models of heat transfer can be used. Computer modeling suggests that radiogenic heat, augmented by exothermic oxidation of organic matter, and with a normal mantle heat flow will explain the autometamorphism of the flysch. Alternative orogenic models invoking pull-apart basins do not explain the great thickness of sediments and absence of volcanic activity.

  16. Chemical Composition and in vitro Antibacterial Activity of the Essential Oil of Verbesina negrensis from the Venezuelan Andes.

    PubMed

    Moraa, Flor D; Rojasa, Yesenia L; Gonzalez, Viviana; Velascob, Judith; Diazb, Tulia; Riosa, Nurby; Rojas, Luis B; Juan Carmona; Silvaa, Bladimiro; Nietod, Marcelo

    2015-07-01

    The composition and antimicrobial activity of the essential oil from Verbesina negrensis Steyerm. leaves is reported. Analysis was performed by GC/MS. Major constituents were α-pinene (43.1%), α-humulene (13.8%), Δ-cadinene (8.1%), limonene (4.6%) and bicyclogermacrene (4.2%). The essential oil showed in vitro activity against the Gram-positive bacteria Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212 (MIC 500 and 350 μL/mL respectively). PMID:26411037

  17. Chemical composition and in vitro antibacterial activity of the essential oil of Phthirusa adunca from Venezuelan Andes.

    PubMed

    Mora, Flor D; Ríos, Nurby; Rojas, Luis B; Díaz, Tulia; Velasco, Judith; Carmona, Juan A; Silva, Bladimiro

    2011-07-01

    In this paper, preliminary studies on the chemical characterization of Phthirusa adunca Meyer essential oil, obtained by hydrodistillation, is presented. The separation of the components was performed by GC-MS. Twenty-three compounds (94.5% of the sample) were identified of which the three major ones (76% of the sample) were beta-phellandrene (38.1%), germacrene D (26.8%) and beta-pinene (11.5%). The essential oil showed a broad spectrum of activity against Salmonella Typhi CDC 57 (100 microg/mL), Staphylococcus aureus ATCC 25923 (200 microg/mL), Enterococcus faecalis ATCC 29212 (250 microg/mL), Escherichia coli ATCC 25922 y Klebsiella pneumoniae ATCC 23357 (500 microg/mL). This is the first report on the composition and activity of the essential oil of this species.

  18. Chemical Composition and in vitro Antibacterial Activity of the Essential Oil of Verbesina negrensis from the Venezuelan Andes.

    PubMed

    Moraa, Flor D; Rojasa, Yesenia L; Gonzalez, Viviana; Velascob, Judith; Diazb, Tulia; Riosa, Nurby; Rojas, Luis B; Juan Carmona; Silvaa, Bladimiro; Nietod, Marcelo

    2015-07-01

    The composition and antimicrobial activity of the essential oil from Verbesina negrensis Steyerm. leaves is reported. Analysis was performed by GC/MS. Major constituents were α-pinene (43.1%), α-humulene (13.8%), Δ-cadinene (8.1%), limonene (4.6%) and bicyclogermacrene (4.2%). The essential oil showed in vitro activity against the Gram-positive bacteria Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212 (MIC 500 and 350 μL/mL respectively).

  19. [Isolation of Helicobacter pylori in gastric mucosa, dental plaque and saliva in a population from the Venezuelan Andes].

    PubMed

    De Sousa, Lilibeth; Vásquez, Libia; Velasco, Judith; Parlapiano, Donatella

    2006-06-01

    Helicobacter pylori infection is common in people. However, the existence of extra gastric reservoirs and transmission routes remain controversial in the field. Because the oral cavity has been proposed as a reservoir for H. pylori, a study was carried out to determine the presence of H. pylori in dental plaque and saliva. The results were asociated with those obtained in the gastric biopsy. Ninety-seven dyspeptic and fifty asymptomatic patients were studied and samples taken for biopsy, dental plaque and saliva. The gastric biopsies were evaluated using microbiology and histology methods. Cultures and urease tests were carried out on the oral cavity samples and included pretreatment methods using urea and HCl. The frequency of H. pylori for all the patients evaluated was 75.5%. H. pylori was not isolated in saliva or dental plaque in any of the two groups studied with or without sample pretreatment. The urease test in dental plaque was positive in 99.3% of the patients and 89.8% in saliva. There was no statistically significant difference between the infection prevalence by H. pylori in dyspeptic or not dyspeptic patients. The obtained results suggest that the methodology used for the detection of H. pylori is not sufficiently sensitive for the determination of the microorganism in the oral cavity.

  20. Civilian control of professionalizing militaries: implications of the Venezuelan case

    SciTech Connect

    Anderson, R.B.

    1985-01-01

    Highly professionalized militaries whose focus is internal security and national development have been shown to be prone to active, directive involvement in politics. In Latin America, this phenomenon has been most notably evident in Brazil since 1964 and Peru between 1968 and 1980. The Venezuelan military offers a case of a more moderately professionalized military which was exposed to the widely disseminated internal security doctrine of the 1960s but, on the surface, exhibited declining levels of militarism. This study examines the varying levels of civilian control in Venezuela between 1945 and 1979 in the context of increasing military professionalization, and seeks to clarify the theoretical relationship between the two variables by using a unique, if not deviant, case. After developing a theoretical definition of the general concept of control, the study derives a definition of civilian control which employs civilian and military behavior, civilian and military attitudes, and military motivations. Application of this definition to the Venezuelan case indicates that civilian control has been more tenuous than more superficial observation would indicate. The study shows that increases in professionalization led to strains on the consolidation of civilian control, while also showing that limits on the level and content of professionalization enabled Venezuela to avoid authoritarian consequences.

  1. [Reference values of fats for the Venezuelan population].

    PubMed

    Giacopini de Z, María; Alonso Villamizar, Hilda; Ruiz, Nelina; Abrahams Ocanto; Martínez, Benailim; Bosch, Virgilio

    2013-12-01

    The present work is a review of the available intormation in the scientific literature in food and human nutrition related to fats and oils, in order to bring a range of guidance on nutritional requirements in pregnancy, infancy, childhood and adulthood, in improving the health and nutritional well-being. Topics include: Characteristics of fatty acids, nomenclature, requirements and recommendations regarding their consumption and its impact on the health situation in Venezuela and recommendations. We present recommendations for total fat requirements and the different fatty acids for different age groups and biological conditions. It was noted that depending on the distribution of fat intake by food of the Venezuelan population energy intake (28.84%) is in line with the recommendations of the FAO/WHO, 2010. Vegetable fats contribute about 62.60% of the total fat where the main source are oils (83.97%) followed by cereals (21.47%) the rest is contributed by vegetables, legumes, vegetables and others. While animal fats represent a 36.84%. Total chiffon, where milk and dairy products account for the highest percentage (47.43%) followed by meat and fish (41.07%), and a lower contribution from eggs (2.07%). This suggests a high ratio n-6/n-3 in feeding conditions Venezuelan general, being necessary to consider ways in which diminish this relationship, in order to prevent cardiovascular disease.

  2. Astrometric Positioning of the Venezuelan Satellite VeneSat-1 "PASAVEN"

    NASA Astrophysics Data System (ADS)

    Otero, S.; Abad, C.; Hernández, R.

    2014-06-01

    By means of this document we inform regarding the collaboration between the Venezuelan institutions, Bolivarian Agency for Space Activities (ABAE) and the Astronomy Research Center (CIDA) with the purpose of using astrometry for the tracking of the Venezuelan Geostationary Satellite Venesat1 by means of optical observation. For this purpose two small astronomical observatories shall be installed on the space tracking ground stations owned by the ABAE in Venezuela and we hope that in a short term they shall be producing the expected results, and also that these observations may be extended to future Venezuelan satellites and to the determination of the geostationary space debris trajectories.

  3. Active tectonics of the Andes

    NASA Astrophysics Data System (ADS)

    Dewey, J. F.; Lamb, S. H.

    1992-04-01

    Nearly 90 mm a -1 of relative plate convergence is absorbed in the Andean plate-boundary zone. The pattern of active tectonics shows remarkable variations in the way in which the plate slip vector is partitioned into displacement and strain and the ways in which compatibility between different segments is solved. Along any traverse across the plate-boundary zone, the sum of relative velocities between points must equal the relative plate motion. We have developed a kinematic synthesis of displacement and strain partitioning in the Andes from 47°S to 5°N relevant for the last 5 Ma based upon: (1) relative plate motion deduced from oceanic circuits giving a roughly constant azimuth between 075 and 080; (2) moment tensor solutions for over 120 crustal earthquakes since 1960; (3) structural studies of deformed Plio-Pleistocene rocks; (4) topographic/geomorphic studies; (5) palaeomagnetic data; and (6) geodetic data. We recognize four neotectonic zones, with subzones and boundary transfer zones, that are partitioned in different ways. These zones are not coincident with the 'classic' zones defined by the presence or absence of a volcanic chain or differences in finite displacements and strains and tectonic form; the long-term segmentation and finite evolution of the Andes may not occur in constantly defined segments in space and time. In Segment 1 (47°-39°S), the slip vector is partitioned into roughly orthogonal Benioff Zone slip with large magnitude/large slip-surface earthquakes and both distributed dextral shear giving clockwise rotations of up to 50° and dextral slip in the curved Liquine-Ofqui Fault System giving 5°-10° of anticlockwise fore-arc rotation. In Segment 2 (39°-20°S), the slip vector is partitioned into Benioff Zone slip roughly parallel with the slip vector, Andean crustal shortening and a very small component of dextral slip, including that on the Atacama Fault System. Between 39° and 34°S, a cross-strike dextral transfer, which deflects

  4. Dynamics, Patterns and Causes of Fires in Northwestern Amazonia

    PubMed Central

    Armenteras, Dolors; Retana, Javier

    2012-01-01

    According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures) and active agricultural frontiers (including illegal crops). Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests. PMID:22523580

  5. Thermochronology and tectonics of the Mérida Andes and the Santander Massif, NW South America

    NASA Astrophysics Data System (ADS)

    van der Lelij, Roelant; Spikings, Richard; Mora, Andrés

    2016-04-01

    New apatite U-Pb and multiphase 40Ar/39Ar data constrain the high to medium temperature (~ 500 °C-~ 300 °C) thermal histories of igneous and metamorphic rocks exposed in the Mérida Andes of Venezuela, and new apatite and zircon fission track data constrain the ~ 500 °C-~ 60 °C thermal histories of pre-Jurassic igneous and metamorphic rocks of the adjacent Santander Massif of Colombia. Computed thermal history envelopes using apatite U-Pb dates and grain size information from an Early Palaeozoic granodiorite in the Mérida Andes suggest that it cooled from > 500 °C to < 350 °C between ~ 266 Ma and ~ 225 Ma. Late Permian to Triassic cooling is also recorded in Early Palaeozoic granitoids and metasedimentary rocks in the Mérida Andes by numerous new muscovite and biotite 40Ar/39Ar plateau dates spanning 257.1 ± 1.0 Ma to 205.1 ± 0.8 Ma. This episode of cooling is not recognised in the Santander Massif, where 40Ar/39Ar data suggest that some Early Palaeozoic rocks cooled below ~ 320 °C in the Early Palaeozoic. However, most data from pre-Jurassic rocks reveal a regional heat pulse at ~ 200 Ma during the intrusion of numerous shallow granitoids, resulting in temperatures in excess of ~ 520 °C, obscuring late Palaeozoic histories. The generally accepted timing of amalgamation of Pangaea along the Ouachita-Marathon suture pre-dates Late Permian to Triassic cooling recorded in basement rocks of the Mérida Andes by > 30 Ma, and its effect on rocks preserved in north-western South America is unknown. We interpret late Permian to Triassic cooling in the Mérida Andes to be driven by exhumation. Previous studies have suggested that a short phase of shortening and anatexis is recorded at ~ 253 Ma in the Maya Block, which may have been adjacent to the basement rocks of the Mérida Andes in the Late Permian. The coeval onset of exhumation in the Mérida Andes may be a result of increased coupling in the magmatic arc, which was located along the western margin of

  6. Reproductive biology of freshwater fishes from the Venezuelan floodplains.

    PubMed

    Guerrero, H Y; Cardillo, E; Poleo, G; Marcano, D

    2009-03-01

    This review describes the endocrine changes that occur during the annual reproductive cycle of Pygocentrus cariba, Pimelodus blochii, and Oxydoras sifontesi and their relationships with the environmental characteristics of Venezuelan floodplains. Most reproductive studies of teleosts have focused on changes that occur during annual cycles in temperate species but, in tropical fish, this has been examined less frequently. P. cariba, P. blochii, and O. sifontesi are seasonal breeders widely distributed along the Orinoco River. Under natural conditions they have an annual gonadal cycle closely related to changes in the annual hydrology cycle of the Orinoco River which defines two seasons on the floodplain: inundation and isolation. The reproductive cycle of these species seems to be controlled by cues from the external environment. Relevant data about gonadal maturation, for example gonadosomatic index and sexual hormones secretion, are contrasted. The role of catecholamines in neuroendocrine control of the reproductive axis is also considered in this work.

  7. Venezuelan equine encephalitis virus transmission and effect on pathogenesis.

    PubMed

    Smith, Darci R; Aguilar, Patricia V; Coffey, Lark L; Gromowski, Gregory D; Wang, Eryu; Weaver, Scott C

    2006-08-01

    Quantifying the dose of an arbovirus transmitted by mosquitoes is essential for designing pathogenesis studies simulating natural infection of vertebrates. Titration of saliva collected in vitro from infected mosquitoes may not accurately estimate titers transmitted during blood feeding, and infection by needle injection may affect vertebrate pathogenesis. We compared the amount of Venezuelan equine encephalitis virus collected from the saliva of Aedes taeniorhynchus to the amount injected into a mouse during blood feeding. Less virus was transmitted by mosquitoes in vivo (geometric mean 11 PFU) than was found for comparable times of salivation in vitro (mean saliva titer 74 PFU). We also observed slightly lower early and late viremia titers in mice that were needle injected with 8 PFU, which represents the low end of the in vivo transmission range. No differences in survival were detected, regardless of the dose or infection route.

  8. Venezuelan Caribbean Sea under the threat of TBT.

    PubMed

    Paz-Villarraga, César Augusto; Castro, Italo B; Miloslavich, Patricia; Fillmann, Gilberto

    2015-01-01

    Although environmental tributyltin (TBT) contamination is considered a solved problem, imposex occurrence in Plicopurpura patula as well as butyltins (BTs) contamination in sediments and tissues were detected along 700 km of the Caribbean coastal shore. Areas under the influence of five main ports of Venezuela were covered, as well as large marinas and sites located away from expected sources. Marinas were the most contaminated areas, whilst imposex incidence and TBT levels were relatively low in areas nearby commercial harbors. Thus, it is evident that marinas have become the main source of fresh TBT to the region. This might explain why imposex incidence seems to be widely distributed along the Venezuelan coast, since leisure boats are circulating along the whole coastal region. In fact, this could be the pattern for other areas of the Caribbean Sea.

  9. Industrial applications of thermal sprayed coatings in Venezuelan steelmaking industry

    NASA Astrophysics Data System (ADS)

    Liscano, S.; Nuñez, E.; Gil, L.; Zerpa, R.

    2013-11-01

    The metal components subjected to high temperature conditions, abrasive wear, corrosion, impact, etc.; tend to present degradation of manufacturing material, causing the failure imminent of the component. One of the alternatives to minimize or eliminate such effect is the application of ceramic coatings, which are thermal insulators and exhibit high mechanical strength. Its extreme hardness, coupled with the low friction properties and chemical stability, allowing its use in a wide variety of applications. Therefore, the following paper describes the application of thermal sprayed coatings obtained by HVOF and Plasma technologies like alternative to protect the metallic equipment in different venezuelan industrial sectors, such as to operate under aggressive conditions of service, such as the steelmaking nationals industries. This study presents applications cases of ceramic-based coatings, in order to minimize the sticking of metallic material in components of reduction reactor of FINMET® and MIDREXTM process.

  10. Reconstruction of Late Cretaceous Magmatic Arcs in the Northern Andes: Single Versus Multiple Arc Systems

    NASA Astrophysics Data System (ADS)

    Cardona, A.; Jaramillo, J. S.; Leon, S.; Hincapie, S.; Mejia, D.; Patino, A. M.; Vanegas, J.; Zapata, S.; Valencia, V.; Jimenez, G.; Monsalve, G.

    2014-12-01

    Although magmatic rocks are major tracers of the geological evolution of convergent margins, pre-collisional events such as subduction erosion, collisional thrusting or late collisional strike slip segmentation may difficult the recognizing of multiple arc systems and therefore the existence of paleogeographic scenarios with multiple subduction systems. New field, U-Pb geochronology and whole rock geochemistry constraints from the northwestern segment of the Central Cordillera in the states of Antioquia and Caldas (Colombia) are used to understand the nature of the Late Cretaceous arc magmatism and evaluate the existence of single or multiple Pacific and Caribbean arc systems in the growth of the Northwestern Andes. The new results integrated with additional field and published information is used to suggest the existence of at least three different magmatic arcs. (1) An Eastern Continental arc built within a well defined Permian to Triassic continental crust that record a protracted 90-70 Ma magmatic evolution, (2) a 90-80 arc formed within attenuated continental crust and associated oceanic crust, (3) 90-88 Ma arc formed over a Late Cretaceous plateau crust. The eastern arcs were formed as part of double eastern vergent subduction system, where the most outboard arc represent a fringing arc formed over detached fragments of continental crust, whereas the easternmost continental arc growth by the closure an subduction of and older and broad Triassic to Early Jurassic back-arc ocean. Its closure also end up in ophiolite emplacement. The third allochtonous oceanic arc was formed over the Caribbean plateau crust and was accreted to the continental margin in the Late Cretaceous. Ongoing paleomagnetic, deformational, gravimetric and basin analysis will be integrate to test this model and understand the complex Late Cretaceous tectonic evolution of the Northern Andes.

  11. Blastomycosis in Northwestern Ontario

    PubMed Central

    McIntyre, Lynn

    1985-01-01

    Nine cases of blastomycosis were seen at the Sioux Lookout Zone Hospital in northwestern Ontario from 1970 to 1983. Although this region has been described as a focus of endemic infection, little published information is available. Seven male and two female Canadian Indians, aged 4-54 years, acquired the infection. Three children were infected; a mother and her son became ill one month apart. All cases presented as progressive pulmonary disease and no extrapulmonary involvement was found. Delay in diagnosis ranged from 11 days to eight weeks, with a mean of 31 days. Patients generally responded favorably to treatment with amphotericin B. Epidemiologic data suggest that environmental, geographic, occupational and recreational determinants are necessary factors in disease acquisition. PMID:21279155

  12. Preliminary Results From the CAUGHT Experiment: Investigation of the North Central Andes Subsurface Using Receiver Functions and Ambient Noise Tomography

    NASA Astrophysics Data System (ADS)

    Ryan, J. C.; Ward, K. M.; Porter, R. C.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2011-12-01

    Jamie Ryan, Kevin M. Ward, Ryan Porter, Susan Beck, George Zandt, Lara Wagner, Estela Minaya, and Hernando Tavera The University of Arizona The University of North Carolina San Calixto Observatorio, La Paz, Bolivia IGP, Lima, Peru In order to investigate the interplay between crustal shortening, lithospheric removal, and surface uplift we have deployed 50 broadband seismometers in northwestern Bolivia and southern Peru as part of the interdisciplinary Central Andean Uplift and Geodynamics of High Topography (CAUGHT) project. The morphotectonic units of the central Andes from west to east, consist of the Western Cordillera, the active volcanic arc, the Altiplano, an internally drained basin (~4 km elevation), the Eastern Cordillera, the high peaks (~6 km elevation) of an older fold and thrust belt, the Subandean zone, the lower elevation active fold and thrust belt, and the foreland Beni basin. Between northwestern Bolivia and southern Peru, the Altiplano pinches out north of Lake Titicaca as the Andes narrow northward. The CAUGHT seismic instruments were deployed between 13° to 18° S latitudes to investigate the crust and mantle lithosphere of the central Andes in this transitional zone. In northwest Bolivia, perpendicular to the strike of the Andes, there is a total of 275 km of documented upper crustal shortening (15° to 17°S) (McQuarrie et al, 2008). Associated with the shortening is crustal thickening and possibly lithospheric removal as the thickening lithospheric root becomes unstable. An important first order study is to compare upper crustal shortening estimates with present day crustal thickness. To estimate crustal thickness, we have calculated receiver functions using an iterative deconvolution method and used common conversion point stacking along the same profile as the geologically based shortening estimates. In our preliminary results, we observed a strong P to S conversion corresponding to the Moho at approximately 60-65 km depth underneath the

  13. Equine pythiosis: report in crossed bred (Criole Venezuelan) horses.

    PubMed

    Salas, Y; Márquez, A; Canelón, J; Perazzo, Y; Colmenárez, V; López, J A

    2012-12-01

    Pythium insidiosum is a pathogenic oomycete known since 1890 that causes pythiosis in mammals. In this report, seven P. insidiosum isolates were recovered from Venezuelan horses and were characterized. The strains were recovered from biopsied tissues and kunkers collected from granulomatous masses located on the hind limb and from a nodular lesion in the left upper eyelid, which decrease the ability of the horses to be used for working purposes. The methods used to identify P. insidiosum isolates were based on the production of sporangia and zoospores, histopathology and PCR assay. To further characterize these strains, portions of the 18S rRNA genes of the seven isolates were sequenced. The sequences showed high homology to previously described P. insidiosum DNA sequences available in GenBank. Similar studies based on the morphological, histological and molecular data identified the etiological agent in samples of granulomatous lesions in these equines as P. insidiosum. In America, the infection has been diagnosed more frequently in equines of Brazil, Colombia, Costa Rica and the United States of America. PMID:22772508

  14. Sedimentology of the Boqueron Field, Eastern Venezuelan Basin

    SciTech Connect

    Aguado, B.; Quintero, M. ); Ramirez, L. )

    1993-02-01

    The Boqueron Field, located in the Carito-El Furrial-Boqueron Trend, a giant field in the Eastern Venezuelan Basin, contains an oil saturated section that comprises both Cretaceous and Tertiary strata. The description of 1300 ft of core allowed the definition of 15 lithofacies including sandy, shaly, carbonatic and even glauconitic rock types. The association of those lithofacies, together with palinological and micropaleontological data, derives in the determination of nearshore, inner to outer platform and slope environments of deposition. The sequence is a good example of a perfect major transgressive cycle as shown by the transition from nearshore bars to a turbidite assemblage through a carbonate-glauconite platform. The producing interval is restricted to nearshore marine sandstone bars and turbiditic channels since the limestones are tight. The bars are subarkosic to sublitharenitic in composition and are very strongly cemented by quartz. Clay mineralogy is formed by mixed-layer illite/smectite, and chlorite. Porosity is due to microcline and orthoclase dissolution. The turbiditic channels are quartzarenitic and most porosity is relict primary, with a contribution from carbonate and glauconite dissolution. Clay mineralogy is composed of kaolinite and chlorite. Even though this field has a high potential of production, it has been dampend by sand plugging that could be related to the environments of deposition and/or the diagenetical evolution of the rocks. Further tests have to be made in order to restrict the sand producing interval.

  15. Characterization of Genetic Variability of Venezuelan Equine Encephalitis Viruses.

    PubMed

    Gardner, Shea N; McLoughlin, Kevin; Be, Nicholas A; Allen, Jonathan; Weaver, Scott C; Forrester, Naomi; Guerbois, Mathilde; Jaing, Crystal

    2016-01-01

    Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne alphavirus that has caused large outbreaks of severe illness in both horses and humans. New approaches are needed to rapidly infer the origin of a newly discovered VEEV strain, estimate its equine amplification and resultant epidemic potential, and predict human virulence phenotype. We performed whole genome single nucleotide polymorphism (SNP) analysis of all available VEE antigenic complex genomes, verified that a SNP-based phylogeny accurately captured the features of a phylogenetic tree based on multiple sequence alignment, and developed a high resolution genome-wide SNP microarray. We used the microarray to analyze a broad panel of VEEV isolates, found excellent concordance between array- and sequence-based SNP calls, genotyped unsequenced isolates, and placed them on a phylogeny with sequenced genomes. The microarray successfully genotyped VEEV directly from tissue samples of an infected mouse, bypassing the need for viral isolation, culture and genomic sequencing. Finally, we identified genomic variants associated with serotypes and host species, revealing a complex relationship between genotype and phenotype. PMID:27054586

  16. Characterization of genetic variability of Venezuelan equine encephalitis viruses

    DOE PAGESBeta

    Gardner, Shea N.; McLoughlin, Kevin; Be, Nicholas A.; Allen, Jonathan; Weaver, Scott C.; Forrester, Naomi; Guerbois, Mathilde; Jaing, Crystal

    2016-04-07

    Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne alphavirus that has caused large outbreaks of severe illness in both horses and humans. New approaches are needed to rapidly infer the origin of a newly discovered VEEV strain, estimate its equine amplification and resultant epidemic potential, and predict human virulence phenotype. We performed whole genome single nucleotide polymorphism (SNP) analysis of all available VEE antigenic complex genomes, verified that a SNP-based phylogeny accurately captured the features of a phylogenetic tree based on multiple sequence alignment, and developed a high resolution genome-wide SNP microarray. We used the microarray to analyze a broadmore » panel of VEEV isolates, found excellent concordance between array- and sequence-based SNP calls, genotyped unsequenced isolates, and placed them on a phylogeny with sequenced genomes. The microarray successfully genotyped VEEV directly from tissue samples of an infected mouse, bypassing the need for viral isolation, culture and genomic sequencing. Lastly, we identified genomic variants associated with serotypes and host species, revealing a complex relationship between genotype and phenotype.« less

  17. Characterization of Genetic Variability of Venezuelan Equine Encephalitis Viruses

    PubMed Central

    Gardner, Shea N.; McLoughlin, Kevin; Be, Nicholas A.; Allen, Jonathan; Weaver, Scott C.; Forrester, Naomi; Guerbois, Mathilde; Jaing, Crystal

    2016-01-01

    Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne alphavirus that has caused large outbreaks of severe illness in both horses and humans. New approaches are needed to rapidly infer the origin of a newly discovered VEEV strain, estimate its equine amplification and resultant epidemic potential, and predict human virulence phenotype. We performed whole genome single nucleotide polymorphism (SNP) analysis of all available VEE antigenic complex genomes, verified that a SNP-based phylogeny accurately captured the features of a phylogenetic tree based on multiple sequence alignment, and developed a high resolution genome-wide SNP microarray. We used the microarray to analyze a broad panel of VEEV isolates, found excellent concordance between array- and sequence-based SNP calls, genotyped unsequenced isolates, and placed them on a phylogeny with sequenced genomes. The microarray successfully genotyped VEEV directly from tissue samples of an infected mouse, bypassing the need for viral isolation, culture and genomic sequencing. Finally, we identified genomic variants associated with serotypes and host species, revealing a complex relationship between genotype and phenotype. PMID:27054586

  18. Characterization of Genetic Variability of Venezuelan Equine Encephalitis Viruses.

    PubMed

    Gardner, Shea N; McLoughlin, Kevin; Be, Nicholas A; Allen, Jonathan; Weaver, Scott C; Forrester, Naomi; Guerbois, Mathilde; Jaing, Crystal

    2016-01-01

    Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne alphavirus that has caused large outbreaks of severe illness in both horses and humans. New approaches are needed to rapidly infer the origin of a newly discovered VEEV strain, estimate its equine amplification and resultant epidemic potential, and predict human virulence phenotype. We performed whole genome single nucleotide polymorphism (SNP) analysis of all available VEE antigenic complex genomes, verified that a SNP-based phylogeny accurately captured the features of a phylogenetic tree based on multiple sequence alignment, and developed a high resolution genome-wide SNP microarray. We used the microarray to analyze a broad panel of VEEV isolates, found excellent concordance between array- and sequence-based SNP calls, genotyped unsequenced isolates, and placed them on a phylogeny with sequenced genomes. The microarray successfully genotyped VEEV directly from tissue samples of an infected mouse, bypassing the need for viral isolation, culture and genomic sequencing. Finally, we identified genomic variants associated with serotypes and host species, revealing a complex relationship between genotype and phenotype.

  19. Challenging the neoliberal trend: the Venezuelan health care reform alternative.

    PubMed

    Muntaner, Carles; Salazar, René M Guerra; Rueda, Sergio; Armada, Francisco

    2006-01-01

    Throughout the 1990s, all Latin American countries but Cuba implemented to varying degrees health care sector reforms underpinned by a neoliberal paradigm that redefined health care as less of a social right and more of a market commodity. These health care sector reforms were couched in the broader structural adjustment of Latin American welfare states prescribed consistently by international financial institutions since the mid-1980s. However, since 2003, Venezuela has been developing an alternative to this neoliberal trend through its health care reform program called Misión Barrio Adentro (Inside the Neighbourhood). In this article, we introduce Misión Barrio Adentro in its historical, political, and economic contexts. We begin by analyzing Latin American neoliberal health sector reforms in their political economic context, with a focus on Venezuela. The analysis reveals that the major beneficiaries of both broader structural adjustment of Latin American welfare states and neoliberal health reforms have been transnational capital interests and domestic Latin American elites. We then provide a detailed description of Misión Barrio Adentro as a challenge to neoliberalism in health care in its political economic context, noting the role played in its development by popular resistance to neoliberalism and the unique international cooperation model upon which it is based. Finally, we suggest that the Venezuelan experience may offer valuable lessons not only to other low- to middle-income countries, but also to countries such as Canada.

  20. Tectonics of the Venezuelan Borderland; An interpretation of magnetometer surveys

    SciTech Connect

    Young, G.A. )

    1993-02-01

    Over 46,000 km of shipborne magnetic surveys and over 64,000 km of aeromagnetic surveys cover the offshore Venezuelan Borderland. The information from these surveys has been assembled into a total intensity map, together with its vertical gradient reduction, and interpreted with respect to the regional tectonics. The distribution and shape of the igneous intrusions and metamorphic rock masses can be clearly recognized as well as the major sedimentary troughs. Areas with similar frequencies and trend directions have been grouped into magnetic provinces in order to better delineate the different structural styles and picture the forces that acted on the basement rocks. The most prominent structures of the Borderland are the nappes and the major transcurrent faults, along which the provinces moved toward the southeast. In the Margarita Province the Margarita-Testigos and La Blanqilla nappes are the most conspicuous. The Delta Province, to the East, is characterized by the complex compression zones that have moved southeastward along the border of the craton. The La Vela region to the West comprises a complex of overriding magnetic provinces. In the exploration for traps with possible accumulations of hydrocarbons, the interpretation of the vertical gradient is the most important as it provides considerable detail on structural patterns. The structures determined by vertical gradient maps coincide very well with those determined by seismic methods in those areas covered by seismic, and thusly, the magnetic maps serve as a reliable guide to structures in areas not yet covered by seismic surveys.

  1. PORTRAYALS OF COLOMBIAN AND VENEZUELAN IMMIGRANT ORGANISATIONS IN THE UNITED STATES

    PubMed Central

    SANCHEZ-R, MAGALY; AYSA-LASTRA, MARIA

    2014-01-01

    This article compares the public images of Colombian and Venezuelan immigrant organisations in the United States. Immigrant organisations’ webpages and the expression of their main aims and goals serve to identify their major concerns as they create public images not only for the organisation but for the immigrant community itself. To interpret the immigrant organisations’ public images and their goals, we offer a multilevel study that considers immigrants’ contexts of exit, which are related to the motivation of migrate and the particular sociodemographic makeup of immigrant groups. This paper adds the Venezuelan immigrant experience to the literature on immigrant organisations. PMID:25324586

  2. Determination of FeS(2) in Venezuelan laterites after a sulphurization process.

    PubMed

    La Brecque, J J; Rosales, P A

    1979-11-01

    A technique is presented for determination of FeS(2) in Venezuelan laterites after a sulphurization process. The determination is based on a reaction with water followed by a turbidimetric determination of sulphate ions in solution. The effect of the reaction time and of the particle size is investigated. Data are given showing the precision to be better than 3%, and the accuracy was studied by preparation of a series of synthetic samples of FeS(2), FeS and Venezuelan laterite. PMID:18962570

  3. [Human rights. Right to health. Right to health information. The Venezuelan biomedical journals].

    PubMed

    Stegemann, Herbert

    2013-06-01

    Venezuelan Biomedical journals have been confronting, for several years, a gradual decline both, from the standpoint of their management and in the quality of their editorial content. At its highest level, Venezuela had about sixty different titles. But irregular financial support, as well as the lack of a clear official policy, regarding these scientific activities, were some of the reasons that have contributed to this decline. Several recent Venezuelan and international documents provide an important legal support for the design of new official policies and government responsibilities. There is now a valid opportunity to profit from new tools to evaluate and improve the quality of our scientific and editorial activities.

  4. Determination of FeS(2) in Venezuelan laterites after a sulphurization process.

    PubMed

    La Brecque, J J; Rosales, P A

    1979-11-01

    A technique is presented for determination of FeS(2) in Venezuelan laterites after a sulphurization process. The determination is based on a reaction with water followed by a turbidimetric determination of sulphate ions in solution. The effect of the reaction time and of the particle size is investigated. Data are given showing the precision to be better than 3%, and the accuracy was studied by preparation of a series of synthetic samples of FeS(2), FeS and Venezuelan laterite.

  5. Diurnal cycle in convergence patterns in the boundary layer east of the Andes and convection

    NASA Astrophysics Data System (ADS)

    Nicolini, Matilde; Skabar, Yanina García

    2011-06-01

    The South American Low-Level Jet Experiment (SALLJEX) provided a unique dataset to investigate the existence of a mesoscale low-level circulation and of a diurnal cycle in its related convergence pattern over the Southeastern South American region east of the Andes, as well as its relationship with deep convection during the warm season. The present paper builds upon high-resolution analyses produced, assimilating the data collected during the SALLJEX field campaign using BRAMS, and explores their capability to reproduce mesoscale circulations not resolved by the low density observational network available in this region. Results of the analyses show a diurnal oscillation signal in the mean boundary layer convergence pattern over the plains with a nocturnal (daytime) convergence (divergence) maximum. These results are coherent with previous findings of a nocturnal phase in the mature stage of organized deep convection and related precipitation in subtropical latitudes east of the Andes during the warm season. The diurnal cycle of convergence/divergence in the boundary layer is described over a 15-day period, during which different synoptic conditions occurred. During weakly forced environments a regime characterized by nocturnal eastward anomaly flow and convergence and daytime westward anomaly flow and divergence related to a mesoscale northwestern mountain-central plain flow regime dominates over the plains between the Andes Mountains, the Parana River Valley, and the southern Brazil mountain range. In contrast, during synoptic conditions dominated by the presence of a deep thermal low over northwestern Argentina and a related low-level jet, convergence at night is mainly accomplished by the predominantly meridional low-level jet, which exhibits an anomalous weak wind speed diurnal cycle with respect to its summer climatological mean. On the other hand daytime divergence is completely produced by the zonal wind component as in the previous synoptic situation

  6. Andes Altiplano, Northwest Argentina, South America

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This view of the Andes Altiplano in northwest Argentina (25.5S, 68.0W) is dominated by heavily eroded older and inactive volcano peaks. The altiplano is a high altitude cold desert like the Tibetan Plateau but smaller in area. It is an inland extension of the hyperarid Atacama Desert of the west coast of South America and includes hundreds of volcanic edifices (peaks, cinder cones, lava flows, debris fields, lakes and dry lake beds (salars).

  7. LANDSAT imagery of the Central Andes

    NASA Technical Reports Server (NTRS)

    Komer, C. A.; Morgan, P.

    1986-01-01

    The central Andes of South America extend from approximately 14 deg. S to 28 deg. S as an unbroken chain of mountains and volcanoes over 2000 km long. It is here that the Nazca plate dives under the South American plate at angles varying from 10 deg to 30 deg. Very little is known about the volcanoes comprising this classic, subduction-type plate margin. A catalogue of the volcanoes in the central Andes is being prepared by Dr. P.W. Francis and Dr. C.A. Wood at the NASA Lunar and Planetary Institute. At present, more than 800 volcanoes of Cenozoic age have been recognized in the chain, with an estimated 75-80 major, active Quarternary volcanoes. Approximately one hundred 1536 x 1536 pixel color composite Optronics positives were produced from six full LANDSAT Thermatic Mapper scenes and three partial TM scenes. These positives cover a large portion of the central Andes. The positives were produced from LANDSAT data using the VAX imaging package, LIPS. The scenes were first transferred from magnetic tape to disk. The LIPS package was then used to select volcanically interesting areas which were then electronically enhanced. Finally, the selected areas were transferred back to tape and printed on the Optronics equipment. The pictures are color composites using LANDSAT TM bands 7,4, and 2 in the red, green, and blue filters, respectively.

  8. Paleosol Proxies for Low Elevation Paleoclimate East of the Andes, Northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Rosario, J. J.; Jordan, T. E.; Garzione, C. N.; Higgins, P.; Hernandez, R.; Hernandez, J.

    2009-12-01

    Paleosols can be used as a proxy for paleoclimate, paleoenvironment, and geomorphological reconstructions. The weathering imprint in the minerals in paleosols can be used as a proxy for moisture conditions, while other environmental information can be obtained from stable isotopes in their minerals such as δ13C and δ18O. The goal of this study is to document changes in paleosol characteristics’ driven by climate change in NW Argentina over the time period between ~14 Ma and 5.1 Ma during a time of significant uplift and climate change in the Altiplano. During this time interval, landscape of the low elevation foreland basin changed as the consequence of the propagation of Andean thrust-fold deformation. Paleosols are interbedded in three stratigraphic sections that are described, sampled, and studied along the Iruya, Peña Colorada, and La Porcelana rivers, distributed from west to east, respectively. Field observations of the paleosols, stratigraphic column construction, thin section petrography and textures, x-ray diffraction (XRD), and stable isotopes together provide climatic proxies. These The stratigraphic columns represent a distributary depositional system, or megafan, whose syn-deformational nature is documented by Echevarría et al. (2003). Argillic-calcic paleosols developed on silty and sandy mudstones in the floodplain environment, with pedogenic calcium carbonate formed as nodules and rizoliths. The Microscopic features show that paleosols on the floodplain contain argillans. Semi-humid to semi-arid conditions are suggested by clay lessivage and calcium carbonate precipitation respectively. The mineralogy reflected by the XRD shows kaolinite, illite, and calcium carbonate in the western stratigraphic column that represents moderate climatic conditions (semi-humid to semi-arid). The coexistence of these minerals suggests seasonal variations in moisture. The eastern columns exhibit wetter soil conditions, including oxide minerals as well as hematite and goethite. Carbon isotopes show C3 vegetation with an increase in δ13C values most likely resulting from increasing seasonality in more recent times. There is little variation in δ18O values through time. In conclusion, these proxies show that soils were developed on interchannel areas, with illuviation of clays during the wet season and precipitation of calcium carbonate during the dry season. Although the megafan migrated eastward and the Altiplano rose, oxygen isotopes suggest that neither rainfall amount nor source of water vapor changed through the approximately 10 million years time interval.

  9. The role of IKKβ in Venezuelan equine encephalitis virus infection.

    PubMed

    Amaya, Moushimi; Voss, Kelsey; Sampey, Gavin; Senina, Svetlana; de la Fuente, Cynthia; Mueller, Claudius; Calvert, Valerie; Kehn-Hall, Kylene; Carpenter, Calvin; Kashanchi, Fatah; Bailey, Charles; Mogelsvang, Soren; Petricoin, Emanuel; Narayanan, Aarthi

    2014-01-01

    Venezuelan equine encephalitis virus (VEEV) belongs to the genus Alphavirus, family Togaviridae. VEEV infection is characterized by extensive inflammation and studies from other laboratories implicated an involvement of the NF-κB cascade in the in vivo pathology. Initial studies indicated that at early time points of VEEV infection, the NF-κB complex was activated in cells infected with the TC-83 strain of VEEV. One upstream kinase that contributes to the phosphorylation of p65 is the IKKβ component of the IKK complex. Our previous studies with Rift valley fever virus, which exhibited early activation of the NF-κB cascade in infected cells, had indicated that the IKKβ component underwent macromolecular reorganization to form a novel low molecular weight form unique to infected cells. This prompted us to investigate if the IKK complex undergoes a comparable macromolecular reorganization in VEEV infection. Size-fractionated VEEV infected cell extracts indicated a macromolecular reorganization of IKKβ in VEEV infected cells that resulted in formation of lower molecular weight complexes. Well-documented inhibitors of IKKβ function, BAY-11-7082, BAY-11-7085 and IKK2 compound IV, were employed to determine whether IKKβ function was required for the production of infectious progeny virus. A decrease in infectious viral particles and viral RNA copies was observed with inhibitor treatment in the attenuated and virulent strains of VEEV infection. In order to further validate the requirement of IKKβ for VEEV replication, we over-expressed IKKβ in cells and observed an increase in viral titers. In contrast, studies carried out using IKKβ(-/-) cells demonstrated a decrease in VEEV replication. In vivo studies demonstrated that inhibitor treatment of TC-83 infected mice increased their survival. Finally, proteomics studies have revealed that IKKβ may interact with the viral protein nsP3. In conclusion, our studies have revealed that the host IKKβ protein may be

  10. [Reference values of niacin for the Venezuelan population].

    PubMed

    Carias, Diamela; García-Casal, María Nieves; Soto de Sanabria, Ingrid; López Rodríguez, Ana Victoria

    2013-12-01

    Niacin is a water soluble vitamin, also known as nicotinic acid or Vitamin B3. Nicotinamide is a derivative of niacin (amide of nicotinic acid), and is used by the body to produce the coenzyme nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), In preparing this review about the niacin requirements for Venezuela, it was found that there is not enough national data to establish recommendations, therefore, as in the 2000 review of the Venezuelan Recommended Dietary Allowances (RDAs), the actual recommendations for intake of niacin, are based on those reported for the United States population. The RDAs for Venezuela are: 2-4 mg/day for infants less than 1 year old, 6-8 mg/day for children between 1 and 8 years, 12 mg/day for children between 9 and 13 years, 14 mg/day for adolescents and female adults, 16 mg/day for adolescents and adult males, 18 mg/day during pregnancy and 17 mg/day during lactation. The estimated average requirement (EAR) is: 6-9 mg/day for children, 11 mg/ day for adolescents and female adults and 12 mg/day for adolescents and adult males, increasing to 14 mg/day during pregnancy and to 13 mg/day during lactation. The niacin Tolerable Upper Intake Levels (UL) are: 10 mg/day for children between 1 and 3 years, 15 mg/day for children between 4 and 8 years, 20 mg/day for children between 9 and 13 years, 30 mg/day for adolescents and 35 mg/day for adults. It is necessary to perform studies where the nutritional status of this vitamin is evaluated for different population groups, including not only the estimation of consumption, but the use of biochemical indicators, such as measuring the levels of the coenzymes NAD and NADP in erythrocytes or whole blood and determination of the major urinary metabolites of the vitamin.

  11. Sickle cell anemia oral manifestations in a Venezuelan population.

    PubMed

    Saint Clair de Velasquez, Y; Rivera, H

    1997-01-01

    Sickle cell anemia (SCA) is a well known hemoglobinopathy which results from a substitution of amino acids in the polypeptidic chain. SCA was considered endemic in certain areas of the world. It has been recognized now that it may have a wide geographic distribution. Few studies have dealt with dental manifestations or complications of SCA (Cox and Soni, 1984). Nevertheless none of them have showed epidemiological data for a large series of oral manifestations. To date, no epidemiological data of our country is available in the literature. The aim of this study was to determine the oral manifestations of SCA in a Venezuelan population. Seventeen patients affected were examined at the University Hospital and the Dental Clinic. Age ranged between 1 1/2-48 years. Each patient was haematologically diagnosed by hemoglobin electrophoresis and only homozygous individuals were selected. Each patient was analyzed according to general clinical history, as well as, dental history; clinical and radiological examination using periapical, panorex and bite-wings radiographs. Our results showed that the most affected group was between 20 to 30 years (41.18%). According to sex, females were more affected than males (64.71%). The most common phenotype was mestizo (47.31%). The most frequent type of hemoglobinopathy was Hg-SS and Hg SS-F. The most common soft tissue oral manifestation was buccal mucosa pallor in 77.05%. In addition, the hard tissue findings involved enlarged medullary spaces (70.58%). Cicatritial infarcts were present in 77.05% of cases and the step-ladder effect was demonstrated in 82.35% of cases. Our observations could be due to genetic, environmental, nutritional and geographical factors. PMID:11885236

  12. The Role of IKKβ in Venezuelan Equine Encephalitis Virus Infection

    PubMed Central

    Amaya, Moushimi; Voss, Kelsey; Sampey, Gavin; Senina, Svetlana; de la Fuente, Cynthia; Mueller, Claudius; Calvert, Valerie; Kehn-Hall, Kylene; Carpenter, Calvin; Kashanchi, Fatah; Bailey, Charles; Mogelsvang, Soren; Petricoin, Emanuel; Narayanan, Aarthi

    2014-01-01

    Venezuelan equine encephalitis virus (VEEV) belongs to the genus Alphavirus, family Togaviridae. VEEV infection is characterized by extensive inflammation and studies from other laboratories implicated an involvement of the NF-κB cascade in the in vivo pathology. Initial studies indicated that at early time points of VEEV infection, the NF-κB complex was activated in cells infected with the TC-83 strain of VEEV. One upstream kinase that contributes to the phosphorylation of p65 is the IKKβ component of the IKK complex. Our previous studies with Rift valley fever virus, which exhibited early activation of the NF-κB cascade in infected cells, had indicated that the IKKβ component underwent macromolecular reorganization to form a novel low molecular weight form unique to infected cells. This prompted us to investigate if the IKK complex undergoes a comparable macromolecular reorganization in VEEV infection. Size-fractionated VEEV infected cell extracts indicated a macromolecular reorganization of IKKβ in VEEV infected cells that resulted in formation of lower molecular weight complexes. Well-documented inhibitors of IKKβ function, BAY-11-7082, BAY-11-7085 and IKK2 compound IV, were employed to determine whether IKKβ function was required for the production of infectious progeny virus. A decrease in infectious viral particles and viral RNA copies was observed with inhibitor treatment in the attenuated and virulent strains of VEEV infection. In order to further validate the requirement of IKKβ for VEEV replication, we over-expressed IKKβ in cells and observed an increase in viral titers. In contrast, studies carried out using IKKβ−/− cells demonstrated a decrease in VEEV replication. In vivo studies demonstrated that inhibitor treatment of TC-83 infected mice increased their survival. Finally, proteomics studies have revealed that IKKβ may interact with the viral protein nsP3. In conclusion, our studies have revealed that the host IKKβ protein may be

  13. The role of IKKβ in Venezuelan equine encephalitis virus infection.

    PubMed

    Amaya, Moushimi; Voss, Kelsey; Sampey, Gavin; Senina, Svetlana; de la Fuente, Cynthia; Mueller, Claudius; Calvert, Valerie; Kehn-Hall, Kylene; Carpenter, Calvin; Kashanchi, Fatah; Bailey, Charles; Mogelsvang, Soren; Petricoin, Emanuel; Narayanan, Aarthi

    2014-01-01

    Venezuelan equine encephalitis virus (VEEV) belongs to the genus Alphavirus, family Togaviridae. VEEV infection is characterized by extensive inflammation and studies from other laboratories implicated an involvement of the NF-κB cascade in the in vivo pathology. Initial studies indicated that at early time points of VEEV infection, the NF-κB complex was activated in cells infected with the TC-83 strain of VEEV. One upstream kinase that contributes to the phosphorylation of p65 is the IKKβ component of the IKK complex. Our previous studies with Rift valley fever virus, which exhibited early activation of the NF-κB cascade in infected cells, had indicated that the IKKβ component underwent macromolecular reorganization to form a novel low molecular weight form unique to infected cells. This prompted us to investigate if the IKK complex undergoes a comparable macromolecular reorganization in VEEV infection. Size-fractionated VEEV infected cell extracts indicated a macromolecular reorganization of IKKβ in VEEV infected cells that resulted in formation of lower molecular weight complexes. Well-documented inhibitors of IKKβ function, BAY-11-7082, BAY-11-7085 and IKK2 compound IV, were employed to determine whether IKKβ function was required for the production of infectious progeny virus. A decrease in infectious viral particles and viral RNA copies was observed with inhibitor treatment in the attenuated and virulent strains of VEEV infection. In order to further validate the requirement of IKKβ for VEEV replication, we over-expressed IKKβ in cells and observed an increase in viral titers. In contrast, studies carried out using IKKβ(-/-) cells demonstrated a decrease in VEEV replication. In vivo studies demonstrated that inhibitor treatment of TC-83 infected mice increased their survival. Finally, proteomics studies have revealed that IKKβ may interact with the viral protein nsP3. In conclusion, our studies have revealed that the host IKKβ protein may be

  14. [Reference values of folic acid for the Venezuelan population].

    PubMed

    García-Casal, María Nieves; Carias, Diamela; Soto de Sanabria, Ingrid; Victoria López, Ana

    2013-12-01

    The review on folic acid requirements for Venezuela comprise the definitions adopted worldwide known as Dietary Reference Intakes (DRIs) that include Recommended Dietary Allowance (RDA), Estimated Average Requirement (EAR), Adequate Intake (AI) and Tolerable Upper Intake Levels (UL). In contrast with the situation in some countries, that required adjustments in fortification policies in order to avoid excessive folic acid consumption, in Venezuela several studies show an elevated prevalence of deficiency. National evidence at this point is insufficient to establish the recommendation, and as in the 2000 review of the Venezuelan RDAs, the actual recommendations are based on the reported for the United States population. The Recommended Dietary Allowances for Venezuela are 65-80 microg/day for infants less than 1 year old, 150-300 microg/day for children and 400 microg/day for adolescents and adults, increasing to 600 microg/day during pregnancy and to 500 microg/day during lactation. The estimated average requirement is 120-250 microg/day for children, 330 microg/day for adolescents, 320 microg/day for adults, 520 microg/day for pregnancy and 450 microg/day during lactation. The tolerable upper intake levels for folic acid are 300-600 microg/day for children, 800 microg/day for adolescents and 1000 microg/day for adults. During pregnancy and lactation the UL is 800 microg/day for pregnant and lactating women between 14 and 18 years of age, and 1000 microg/day for older pregnant and lactating women. The continuous evaluation of folic acid status is important to design adequate and efficient policies to control both, the deficiency and the excess of folic acid consumption.

  15. A new case of an Holarctic element in the Colombian Andes: first record of Cordyla Meigen (Diptera, Mycetophilidae) from the Neotropical region.

    PubMed

    Kurina, Olavi; Oliveira, Sarah Siqueira

    2015-01-01

    Three new species of Mycetophilidae - Cordyla monticola sp. n., Cordyla pseudopusilla sp. n. and Cordyla reducta sp. n. - are described from the Colombian Andes, representing the first described species of Cordyla Meigen from the Neotropical region. Colour photos of their habitus, wing and terminalia are provided. The morphological affinities of male terminalia are discussed in a worldwide context. The distributional pattern of the genus clearly indicates a case of northern elements reaching the north-western region of the Neotropics that corresponds to a secondary extension of a Holarctic clade to the south. PMID:26445929

  16. A new case of an Holarctic element in the Colombian Andes: first record of Cordyla Meigen (Diptera, Mycetophilidae) from the Neotropical region

    PubMed Central

    Kurina, Olavi; Oliveira, Sarah Siqueira

    2015-01-01

    Abstract Three new species of Mycetophilidae – Cordyla monticola sp. n., Cordyla pseudopusilla sp. n. and Cordyla reducta sp. n. – are described from the Colombian Andes, representing the first described species of Cordyla Meigen from the Neotropical region. Colour photos of their habitus, wing and terminalia are provided. The morphological affinities of male terminalia are discussed in a worldwide context. The distributional pattern of the genus clearly indicates a case of northern elements reaching the north-western region of the Neotropics that corresponds to a secondary extension of a Holarctic clade to the south. PMID:26445929

  17. Focal epithelial hyperplasia: human-papillomavirus-induced disease with a genetic predisposition in a Venezuelan family.

    PubMed

    Premoli-De-Percoco, G; Cisternas, J P; Ramírez, J L; Galindo, I

    1993-05-01

    A study on the presence of human papillomavirus (HPV) DNA sequences and focal epithelial hyperplasia (FEH) in a family of Venezuelan ancestry has revealed that FEH is an HPV-induced disease presenting familial aggregation. The genealogical evidence indicates a genetic predisposition to the disease.

  18. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Encephalomyelitis Vaccine, Eastern... PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus. Encephalomyelitis Vaccine, Eastern, Western,...

  19. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Encephalomyelitis Vaccine, Eastern... PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus. Encephalomyelitis Vaccine, Eastern, Western,...

  20. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Encephalomyelitis Vaccine, Eastern... PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus. Encephalomyelitis Vaccine, Eastern, Western,...

  1. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Encephalomyelitis Vaccine, Eastern... PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus. Encephalomyelitis Vaccine, Eastern, Western,...

  2. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Encephalomyelitis Vaccine, Eastern... PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus. Encephalomyelitis Vaccine, Eastern, Western,...

  3. The basement of the Eastern Cordillera, Colombia: An allochthonous terrane in northwestern South America

    NASA Astrophysics Data System (ADS)

    Forero Suarez, A.

    The fault system of the Borde Llanero of Colombia represents the limit between two early Paleozoic geologic provinces: the Guiana Shield (Gondwana) to the east, and an allochthonous terrane — formerly a piece of the North American continent — to the west. The Baudó Range, the Western Cordillera, and the western flank of the Central Cordillera are the result of post-Jurassic accretion. In contrast the pre-Emsian metamorphic rocks of the eastern flank of the Central Cordillera, of the Eastern Cordillera of Colombia, and of the Mérida Andes correspond to an allochthonous terrane that was accreted to the north-western continental border of South America during the collision between North America and Gondwana in Silurian-Early Devonian times. Geochronologic and petrographic data indicate the presence of the Grenvillian granulite belt, represented by the Garzón-Sierra Nevada de Santa Marta belt. This belt is separated from the Guiana Shield by a magmatic tract which is parallel to the Borde Llanero of Venezuela and Colombia. The late Paleozoic regional metamorphism in the Northern Andes of Colombia occurred during Late Silurian-Early Devonian times. Since the late Emsian, a sedimentary cycle was initiated on this allochthonous basement. The faunal records of northwestern South America and the North American continent are indistinguishable for that time. This similarity clearly shows that both northwestern South America and the North American regions of the Appalachians and New Mexico belong to the same paleobiogeographic province. The faunal communication in this case supports the idea of the immediate neighborhood of the two continents.

  4. Changing Student Attitudes using Andes, An Intelligent Homework System

    NASA Astrophysics Data System (ADS)

    van de Sande, Brett; VanLehn, K.; Treacy, D.; Shelby, R.

    2006-12-01

    The size of introductory physics lectures often inhibits personal homework assistance and timely corrective feedback. Andes, an intelligent homework system designed for two semesters of introductory physics, can fill this need by encouraging students to use sound problem solving techniques and providing immediate feedback on each step of a solution. On request, Andes provides principles-based hints based on previous student actions. A multi-year study at the U.S. Naval Academy demonstrate that students using Andes perform better than students working the same problems as graded pencil and paper homeworks. In addition, student attitude surveys show that Andes is preferred over other homework systems. These findings have implications for student attitudes toward, and mastery of, physics. See http://www.andes.pitt.edu for more information.

  5. Changing Student Attitudes using Andes, An Intelligent Homework System

    NASA Astrophysics Data System (ADS)

    van de Sande, Brett; Vanlehn, Kurt; Treacy, Don; Shelby, Bob; Wintersgill, Mary

    2007-03-01

    The size of introductory physics lectures often inhibits personal homework assistance and timely corrective feedback. Andes, an intelligent homework help system designed for two semesters of introductory physics, can fill this need by encouraging students to use sound problem solving techniques and providing immediate feedback on each step of a solution. On request, Andes provides principles-based hints based on previous student actions. A multi-year study at the U.S. Naval Academy demonstrates that students using Andes perform better than students working the same problems as graded pencil and paper homeworks. In addition, student attitude surveys show that Andes is preferred over other homework systems. These findings have implications for student attitudes toward, and mastery of, physics. See http://www.andes.pitt.edu for more information.

  6. Panoramic View of the Andes Mountains, Chile and Argentina

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This panoramic view of the Andes Mountains of Chile and Argentina (24.5S, 69.5W) is dominated by the yellows and browns of the coastal Atacama Desert and the full width of the Andes altiplano, about 300 miles. Winter snow can be seen capping the 22,000 to 23,000 ft. peaks of the Andes. Wisps of cirrus clouds lie over the altiplano and offshore fog obscures the coast. In the distance, the low Chaco Plain appears green with pastures and agriculture.

  7. The use of radar and LANDSAT data for mineral and petroleum exploration in the Los Andes region, Venezuela

    NASA Technical Reports Server (NTRS)

    Vincent, R. K.

    1980-01-01

    A geological study of a 27,500 sq km area in the Los Andes region of northwestern Venezuela was performed which employed both X-band radar mosaics and computer processed Landsat images. The 3.12 cm wavelength radar data were collected with horizontal-horizontal polarization and 10 meter spatial resolution by an Aeroservices SAR system at an altitude of 12,000 meters. The radar images increased the number of observable suspected fractures by 27 percent over what could be mapped by LANDSAT alone, owing mostly to the cloud cover penetration capabilities of radar. The approximate eight fold greater spatial resolution of the radar images made possible the identification of shorter, narrower fractures than could be detected with LANDSAT data alone, resulting in the discovery of a low relief anticline that could not be observed in LANDSAT data. Exploration targets for petroleum, copper, and uranium were identified for further geophysical work.

  8. Magnetic properties of NiFe2O4/carbon nanofibers from Venezuelan petcoke

    NASA Astrophysics Data System (ADS)

    Briceño, Sarah; Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi; Cañizales, Edgard

    2015-05-01

    NiFe2O4/carbon nanofibers (NiFe2O4/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe2O4 as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe2O4/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs.

  9. Venezuelan Equine Encephalitis Virus Activity in the Gulf Coast Region of Mexico, 2003–2010

    PubMed Central

    Adams, A. Paige; Navarro-Lopez, Roberto; Ramirez-Aguilar, Francisco J.; Lopez-Gonzalez, Irene; Leal, Grace; Flores-Mayorga, Jose M.; Travassos da Rosa, Amelia P. A.; Saxton-Shaw, Kali D.; Singh, Amber J.; Borland, Erin M.; Powers, Ann M.; Tesh, Robert B.; Weaver, Scott C.; Estrada-Franco, Jose G.

    2012-01-01

    Venezuelan equine encephalitis virus (VEEV) has been the causative agent for sporadic epidemics and equine epizootics throughout the Americas since the 1930s. In 1969, an outbreak of Venezuelan equine encephalitis (VEE) spread rapidly from Guatemala and through the Gulf Coast region of Mexico, reaching Texas in 1971. Since this outbreak, there have been very few studies to determine the northward extent of endemic VEEV in this region. This study reports the findings of serologic surveillance in the Gulf Coast region of Mexico from 2003–2010. Phylogenetic analysis was also performed on viral isolates from this region to determine whether there have been substantial genetic changes in VEEV since the 1960s. Based on the findings of this study, the Gulf Coast lineage of subtype IE VEEV continues to actively circulate in this region of Mexico and appears to be responsible for infection of humans and animals throughout this region, including the northern State of Tamaulipas, which borders Texas. PMID:23133685

  10. Viremia in young herons and ibis infected with Venezuelan encephalitis virus.

    PubMed

    Dickerman, R W; Bonacorsa, C M; Scherer, W F

    1976-12-01

    Fifty-seven of 61 nestling, 8- to 30-day-old herons of three species (Black-crowned Night Heron, Great Egret, and Snowy Egret), developed viremia lasting one to three days following subcutaneous inoculation with small doses of endemic or epidemic strains of Venezuelan encephalitis virus from Mexico, Guatemala or Venezuela. Two epidemic strains from Guatemala or Venezuela stimulated levels of viremia similar to those following infection with enzootic strains. Great Egrets, Striated and Boat-billed Herons and Scarlet Ibis older than 30 days of age developed viremias of lower levels and shorter durtions than did young birds. Marked differences in levles of viremia were not observed among Black-crowned Night Herons, Great Egrets, or Snowy Egrets. Over 50% of viremic blood samples from herons 8-30 days of age contained 1000 or more chick embryo cell culture plaque forming units of Venezuelan encephalitis per ml, levels sufficient to infect some vector species mosquitoes.

  11. The Bolivian Orocline and its implications for the origin of the central Andes

    NASA Astrophysics Data System (ADS)

    Arriagada, C.

    2015-12-01

    The tectonic evolution of the Central Andes includes a complex combination of thrusting, wrenching and block rotation leading progressively to the curvature of the orogenic system of the South American continental margin at 18ºS (Bolivian Orocline). Tectonic deformation in the Bolivian Orocline cannot be realistically restored using information from balanced cross sections alone, as the deformation includes an important component of block rotation, associated to counterclockwise block rotation in southern Peru and clockwise rotation in northern Chile. Recent work shows that block rotations in the forearc are essentially pre-early Miocene, predating the onset of Neogene shortening in the Sub Andean zone. Most rotations in the forearc of northern Chile where acquired through a single tectonic event during the Paleogene-early Miocene which probably coincides with the Eocene orogen-wide Incaic event which affected large regions of the central Andes between ca. 50 and 40 Ma. Results from 2D restoration experiments support the hypothesis of the Paleogene formation of the Bolivian Orocline, as a consequence of differential shortening, concentrated in the Eastern Cordillera of Bolivia, southern Peru and northwestern Argentina. Within the southern central Andes four additional curvatures including striking changes in the pattern of rotations have been discovered. From north to south these are the Antofagasta-Calama Lineament, Vallenar, Maipo and Arauco oroclines. However, an important part of rotation needs to be balanced, in the forearc region, by two major conjugate oblique shear zones (Abancay Deflection and Antofagasta-Calama Lineament). These structural features are probably related to inherited lithospheric discontinuities associated with the accretion of basement terranes which could be responsible for producing and delimitating significant and abrupt changes in the magnitude of the Central Andean Rotation Pattern along the margin. While shortening and crustal

  12. Stratigraphic and Petrological Constraints of Cretaceous Subduction Initiation and Arc-Continent Collision in the Northern Andes

    NASA Astrophysics Data System (ADS)

    Leon, S.; Cardona, A.; Mejia, D.; Parra, M.

    2014-12-01

    Middle to Late-Cretaceous orogenic events in the northern Andes have been commonly reconstructed from the analysis of inland basins or the integration of regional scale thermochronological, geochronological and geochemical datasets from the accreted blocks. In contrast, limited studies have been developed on the stratigraphic and deformational record of magmatic and sedimentary sequences exposed near the suture zones. New field and petrologic data are used to characterize an ophiolite type sequence that outcrops in the western flank from the northwestern segment of the Central Cordillera of Colombia. Stratigraphic analysis indicate the existence of Albian-Aptian deep marine pelitic sequence interbedded with minor chert and thin quartz sandstone beds that apparently change to a volcanic dominate stratigraphy. Deformed ophiolite-like mafic and ultramafic plutonic rocks and isolated pillow lavas are also exposed to the east in fault contact with the pelitic sequence. The pelitic and interlayered volcanic rocks represent the growth of an extensional Early-Cretaceous basin that followed a Late-Jurassic magmatic quiescence in the Northern Andes. The volcano-sedimentary record is probably related to the growth of a fore-arc basin in a new subduction zone that extends until the Late Cretaceous. The deformation and obduction of the ophiolitic association and the fore-arc basin were probably triggered by the Late Cretaceous collision with an allocthonous plateau-arc associated to the migration of the Caribbean plate.

  13. A melting pot of multicontinental mtDNA lineages in admixed Venezuelans.

    PubMed

    Gómez-Carballa, Alberto; Ignacio-Veiga, Ana; Alvarez-Iglesias, Vanesa; Pastoriza-Mourelle, Ana; Ruíz, Yarimar; Pineda, Lennie; Carracedo, Angel; Salas, Antonio

    2012-01-01

    The arrival of Europeans in Colonial and post-Colonial times coupled with the forced introduction of sub-Saharan Africans have dramatically changed the genetic background of Venezuela. The main aim of the present study was to evaluate, through the study of mitochondrial DNA (mtDNA) variation, the extent of admixture and the characterization of the most likely continental ancestral sources of present-day urban Venezuelans. We analyzed two admixed populations that have experienced different demographic histories, namely, Caracas (n = 131) and Pueblo Llano (n = 219). The native American component of admixed Venezuelans accounted for 80% (46% haplogroup [hg] A2, 7% hg B2, 21% hg C1, and 6% hg D1) of all mtDNAs; while the sub-Saharan and European contributions made up ∼10% each, indicating that Trans-Atlantic immigrants have only partially erased the native American nature of Venezuelans. A Bayesian-based model allowed the different contributions of European countries to admixed Venezuelans to be disentangled (Spain: ∼38.4%, Portugal: ∼35.5%, Italy: ∼27.0%), in good agreement with the documented history. Seventeen entire mtDNA genomes were sequenced, which allowed five new native American branches to be discovered. B2j and B2k, are supported by two different haplotypes and control region data, and their coalescence ages are 3.9 k.y. (95% C.I. 0-7.8) and 2.6 k.y. (95% C.I. 0.1-5.2), respectively. The other clades were exclusively observed in Pueblo Llano and they show the fingerprint of strong recent genetic drift coupled with severe historical consanguinity episodes that might explain the high prevalence of certain Mendelian and complex multi-factorial diseases in this region. PMID:22120584

  14. [Thesis for induction into the Venezuelan Society for the History of Medicine: Medical deontology in Venezuela].

    PubMed

    Rago, V

    1992-12-01

    After a brief reference to his predecessor, the author presents a review on deontological principles put to use in the Venezuelan medicine, from the discovery to this century, after some considerations on the roles played by the state, the universities and the society. Finally, the importance of the moral compromise of the medical doctor as a professional who must have a faultless behaviour is highlighted.

  15. Demographics of natural oral infection of mosquitos by Venezuelan equine encephalitis virus.

    PubMed

    Gutiérrez, Serafín; Thébaud, Gaël; Smith, Darci R; Kenney, Joan L; Weaver, Scott C

    2015-04-01

    The within-host diversity of virus populations can be drastically limited during between-host transmission, with primary infection of hosts representing a major constraint to diversity maintenance. However, there is an extreme paucity of quantitative data on the demographic changes experienced by virus populations during primary infection. Here, the multiplicity of cellular infection (MOI) and population bottlenecks were quantified during primary mosquito infection by Venezuelan equine encephalitis virus, an arbovirus causing neurological disease in humans and equids.

  16. Three new species of woodlizards (Hoplocercinae, Enyalioides) from northwestern South America

    PubMed Central

    Torres-Carvajal, Omar; Venegas, Pablo J.; de Queiroz, Kevin

    2015-01-01

    Abstract The discovery of three new species of Enyalioides from the tropical Andes in Ecuador and northern Peru is reported. Enyalioides altotambo sp. n. occurs in northwestern Ecuador and differs from other species of Enyalioides in having dorsal scales that are both smooth and homogeneous in size, a brown iris, and in lacking enlarged, circular and keeled scales on the flanks. Enyalioides anisolepis sp. n. occurs on the Amazonian slopes of the Andes in southern Ecuador and northern Peru and can be distinguished from other species of Enyalioides by its scattered, projecting large scales on the dorsum, flanks, and hind limbs, as well as a well-developed vertebral crest, with the vertebrals on the neck at least three times higher than those between the hind limbs. Enyalioides sophiarothschildae sp. n. is from the Amazonian slopes of the Cordillera Central in northeastern Peru; it differs from other species of Enyalioides in having caudal scales that are relatively homogeneous in size on each caudal segment, a white gular region with a black medial patch and several turquoise scales in males, as well as immaculate white labials and chin. A molecular phylogenetic tree of 18 species of hoplocercines is presented, including the three species described in this paper and Enyalioides cofanorum, as well as an updated identification key for species of Hoplocercinae. PMID:25901116

  17. Three new species of woodlizards (Hoplocercinae, Enyalioides) from northwestern South America.

    PubMed

    Torres-Carvajal, Omar; Venegas, Pablo J; de Queiroz, Kevin

    2015-01-01

    The discovery of three new species of Enyalioides from the tropical Andes in Ecuador and northern Peru is reported. Enyalioidesaltotambo sp. n. occurs in northwestern Ecuador and differs from other species of Enyalioides in having dorsal scales that are both smooth and homogeneous in size, a brown iris, and in lacking enlarged, circular and keeled scales on the flanks. Enyalioidesanisolepis sp. n. occurs on the Amazonian slopes of the Andes in southern Ecuador and northern Peru and can be distinguished from other species of Enyalioides by its scattered, projecting large scales on the dorsum, flanks, and hind limbs, as well as a well-developed vertebral crest, with the vertebrals on the neck at least three times higher than those between the hind limbs. Enyalioidessophiarothschildae sp. n. is from the Amazonian slopes of the Cordillera Central in northeastern Peru; it differs from other species of Enyalioides in having caudal scales that are relatively homogeneous in size on each caudal segment, a white gular region with a black medial patch and several turquoise scales in males, as well as immaculate white labials and chin. A molecular phylogenetic tree of 18 species of hoplocercines is presented, including the three species described in this paper and Enyalioidescofanorum, as well as an updated identification key for species of Hoplocercinae.

  18. Three new species of woodlizards (Hoplocercinae, Enyalioides) from northwestern South America.

    PubMed

    Torres-Carvajal, Omar; Venegas, Pablo J; de Queiroz, Kevin

    2015-01-01

    The discovery of three new species of Enyalioides from the tropical Andes in Ecuador and northern Peru is reported. Enyalioidesaltotambo sp. n. occurs in northwestern Ecuador and differs from other species of Enyalioides in having dorsal scales that are both smooth and homogeneous in size, a brown iris, and in lacking enlarged, circular and keeled scales on the flanks. Enyalioidesanisolepis sp. n. occurs on the Amazonian slopes of the Andes in southern Ecuador and northern Peru and can be distinguished from other species of Enyalioides by its scattered, projecting large scales on the dorsum, flanks, and hind limbs, as well as a well-developed vertebral crest, with the vertebrals on the neck at least three times higher than those between the hind limbs. Enyalioidessophiarothschildae sp. n. is from the Amazonian slopes of the Cordillera Central in northeastern Peru; it differs from other species of Enyalioides in having caudal scales that are relatively homogeneous in size on each caudal segment, a white gular region with a black medial patch and several turquoise scales in males, as well as immaculate white labials and chin. A molecular phylogenetic tree of 18 species of hoplocercines is presented, including the three species described in this paper and Enyalioidescofanorum, as well as an updated identification key for species of Hoplocercinae. PMID:25901116

  19. Title Sheet, National Home for Disabled Volunteer Soldiers, Northwestern Branch ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Title Sheet, National Home for Disabled Volunteer Soldiers, Northwestern Branch - National Home for Disabled Volunteer Soldiers, Northwestern Branch, 5000 West National Avenue, Milwaukee, Milwaukee County, WI

  20. Late Tertiary northwestward-vergent thrusting in Valle del Cauca, Colombian Andes

    SciTech Connect

    Alfonso, C.A.; Sacks, P.E.; Secor, D.T. Jr.; Cordoba, F.

    1989-03-01

    The Valle del Cauca is a topographic basin situated between the Cordillera Central and the Cordillera Occidental in the Colombian Andes. The basement is Mesozoic mafic igneous rock of the Volcanic and Amaime Formations and clastic sediments and chert of the Espinal and Cisneros Formations. The basement was intruded by middle Cretaceous granodiorites (including the Batolito de Buga) and was deformed and metamorphosed to greenschist facies. The Mesozoic rocks originated in an oceanic setting and were accreted to northwestern South America during the Cretaceous or early Tertiary. Unconformably overlying the Mesozoic basement are the Eocene and Oligocene Vijes (marine limestone) and Guachinte and Cinta de Piedra (fluvial and deltaic sandstone and mudstone). In the Cordillera Central, the Cinta de Piedra is unconformably overlain by fanglomerate of the Miocene La Paila Formation. These clastics coarsen and thicken eastward. Geologic mapping and structural analyses show that the Mesozoic basement and its Tertiary cover are faulted and folded. Folds are asymmetric and overturned westward. Faults dip at shallow to moderate angles to the east and carry older sedimentary or basement rocks westward over younger rocks.

  1. Chemical composition and in vitro antibacterial activity of the essential oil of Minthostachys mollis (Kunth) Griseb Vaught from the Venezuelan Andes.

    PubMed

    Mora, Flor D; Araque, María; Rojas, Luis B; Ramirez, Rosslyn; Silva, Bladimiro; Usubillaga, Alfredo

    2009-07-01

    Chemical constituents of the essential oil from the leaves of Minthostachys mollis (Kunth) Griseb Vaught var. mollis collected in January 2008 at Tuñame, Trujillo State, Venezuela, were separated and identified by GC-MS analysis. The essential oil was obtained by hydrodistillation and thirteen components (98.5% of the sample) were identified by comparison with the Wiley GC-MS library data base. The two major components were pulegone (55.2%) and trans-menthone (31.5%). The essential oil showed a significant inhibitory effect against Gram-positive and Gram-negative bacteria, especially Bacillus subtilis and Salmonella typhi (4 microg/mL).

  2. The presence-absence situation and its impact on the assemblage structure and interspecific relations of Pronophilina butterflies in the Venezuelan Andes (Lepidoptera: Nymphalidae).

    PubMed

    Pyrcz, T W; Garlacz, R

    2012-06-01

    Assemblage structure and altitudinal patterns of Pronophilina, a species-rich group of Andean butterflies, are compared in El Baho and Monte Zerpa, two closely situated and ecologically similar Andean localities. Their faunas differ only by the absence of Pedaliodes ornata Grose-Smith in El Baho. There are, however, important structural differences between the two Pronophilina assemblages. Whereas there are five co-dominant species in Monte Zerpa, including P. ornata, Pedaliodes minabilis Pyrcz is the only dominant with more than half of all the individuals in the sample in El Baho. The absence of P. ornata in El Baho is investigated from historical, geographic, and ecological perspectives exploring the factors responsible for its possible extinction including climate change, mass dying out of host plants, and competitive exclusion. Although competitive exclusion between P. ornata and P. minabilis is a plausible mechanism, considered that their ecological niches overlap, which suggests a limiting influence on each other's populations, the object of competition was not identified, and the reason of the absence of P. ornata in El Baho could not be established. The role of spatial interference related to imperfect sexual behavioral isolation is evaluated in maintaining the parapatric altitudinal distributions of three pairs of phenotypically similar and related species of Pedaliodes, Corades, and Lymanopoda.

  3. Landsat Thematic Mapper (TM) Images of the Andes as a Classroom Tool.

    ERIC Educational Resources Information Center

    Bloom, Arthur L.; Fox, Andrew N.

    1990-01-01

    Described is the use of Thematic Mapper images in undergraduate geology instruction. The work of the Andes Project at Cornell University is discussed. Digitally enhanced illustrations of landforms in the Andes mountains of South America are provided. (CW)

  4. ANDES Measurements for Advanced Reactor Systems

    NASA Astrophysics Data System (ADS)

    Plompen, A. J. M.; Hambsch, F.-J.; Kopecky, S.; Nyman, M.; Rouki, C.; Salvador Castiñeira, P.; Schillebeeckx, P.; Belloni, F.; Berthoumieux, E.; Gunsing, F.; Lampoudis, C.; Calviani, M.; Guerrero, C.; Cano-Ott, D.; Gonzalez Romero, E.; Aïche, M.; Jurado, B.; Mathieu, L.; Derckx, X.; Farget, F.; Rodrigues Tajes, C.; Bacquias, A.; Dessagne, Ph.; Kerveno, M.; Borcea, C.; Negret, A.; Colonna, N.; Goncalves, I.; Penttilä, H.; Rinta-Antila, S.; Kolhinen, V. S.; Jokinen, A.

    2014-05-01

    A significant number of new measurements was undertaken by the ANDES “Measurements for advanced reactor systems” initiative. These new measurements include neutron inelastic scattering from 23Na, Mo, Zr, and 238U, neutron capture cross sections of 238U, 241Am, neutron induced fission cross sections of 240Pu, 242Pu, 241Am, 243Am and 245Cm, and measurements that explore the limits of the surrogate technique. The latter study the feasibility of inferring neutron capture cross sections for Cm isotopes, the neutron-induced fission cross section of 238Pu and fission yields and fission probabilities through full Z and A identification in inverse kinematics for isotopes of Pu, Am, Cm and Cf. Finally, four isotopes are studied which are important to improve predictions for delayed neutron precursors and decay heat by total absorption gamma-ray spectrometry (88Br, 94Rb, 95Rb, 137I). The measurements which are performed at state-of-the-art European facilities have the ambition to achieve the lowest possible uncertainty, and to come as close as is reasonably achievable to the target uncertainties established by sensitivity studies. An overview is presented of the activities and achievements, leaving detailed expositions to the various parties contributing to the conference.

  5. The first ANDES elements: 9-DOF plate bending triangles

    NASA Technical Reports Server (NTRS)

    Militello, Carmelo; Felippa, Carlos A.

    1991-01-01

    New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.

  6. Evidencing decadal and interdecadal hydroclimatic variability over the Central Andes

    NASA Astrophysics Data System (ADS)

    Segura, Hans; Carlo Espinoza, Jhan; Junquas, Clementine; Takahashi, Ken

    2016-09-01

    In this study we identified a significant low frequency variability (8 to 20 years) that characterizes the hydroclimatology over the Central Andes. Decadal-interdecadal variability is related to the central-western Pacific Ocean (R 2 = 0.50) and the zonal wind at 200 hPa above the Central Andes (R 2 = 0.66). These two oceanic-atmospheric variables have a dominant decadal-interdecadal variability, and there is a strong relationship between them at a low frequency time scale (R 2 = 0.66). During warming decades in the central-western Pacific Ocean, westerlies are intensified at 200 hPa above the Central Andes, which produce decadal periods of hydrological deficit over this region. In contrast, when the central-western Pacific Ocean is cooler than usual, easterly anomalies prevail over the Central Andes, which are associated with decades of positive hydrological anomalies over this region. Our results indicate that impacts of El Niño on hydrology over the Central Andes could be influenced by the low frequency variability documented in this study.

  7. Late Pleistocene and Holocene Hydroclimate Variability in the Tropical Andes from Alpine Lake Sediments, Cordillera de Mérida, Venezuela

    NASA Astrophysics Data System (ADS)

    Larsen, D. J.; Abbott, M. B.; Polissar, P. J.

    2014-12-01

    The tropics play a major role in the global hydrologic cycle and changes to tropical rainfall patterns have critical implications for water resources and ecosystem dynamics over large geographic scales. In tropical South America, late Pleistocene and Holocene precipitation variability has been documented in geologic records and associated with numerous external and internal variables, including changes in summer insolation, South American summer monsoon strength, Pacific Ocean sea surface temperatures, continental moisture recycling, and other climate processes. However, there are few records from the northern hemisphere tropical Americas, a key region for understanding interhemispheric linkages and the drivers of tropical hydroclimate variability. Here, we present a ~13 ka record of coupled hydroclimate and environmental changes from Laguna Brava, a small (~0.07 km2), hydrologically closed lake basin situated at 2400 m asl in the Cordillera de Mérida, Venezuela. Sediment cores collected from varying water depths and proximity to shore are placed in a chronologic framework using radiocarbon ages from terrestrial macrofossils, and analyzed for a suite of physical, bulk geochemical, and stable isotopic parameters. Compound specific hydrogen isotope (D/H) measurements of terrestrial plant waxes (long-chain n-alkanes) show a sharp increase in the late Pleistocene, followed by a long-term trend toward more negative values that suggest a ~20‰ decrease in the D/H ratios of South American tropical precipitation during the Holocene. This pattern is consistent in sign and magnitude to other South American precipitation reconstructions from both hemispheres, indicating interhemispheric similarities in tropical hydroclimate variability. Superimposed on this continent-scale trend are changes in moisture balance and environmental conditions in the Venezuelan Andes. We reconstruct these parameters at Laguna Brava at multidecadal and centennial resolution and evaluate this

  8. Meta-information system facilitates use of complex data related to Andes

    NASA Astrophysics Data System (ADS)

    Ott, N.; Götze, H.-J.; Schmidt, S.; Burger, H.; Alten, M.

    Studies of the Collaborative Research Center 267, "Deformation Processes in the Andes," focus on interdisciplinary geoscientific research in the central and Patagonian Andes involving all disciplines of geoscience. The combination of geophysical and geological field research, Global Positioning System monitoring, penological and geochemical analysis, age dating, and remote sensing provides new insight into the structure and tectonic evolution of the Andes.

  9. Forensic Analysis of Venezuelan Elections during the Chávez Presidency

    PubMed Central

    Jiménez, Raúl; Hidalgo, Manuel

    2014-01-01

    Hugo Chávez dominated the Venezuelan electoral landscape since his first presidential victory in 1998 until his death in 2013. Nobody doubts that he always received considerable voter support in the numerous elections held during his mandate. However, the integrity of the electoral system has come into question since the 2004 Presidential Recall Referendum. From then on, different sectors of society have systematically alleged electoral irregularities or biases in favor of the incumbent party. We have carried out a thorough forensic analysis of the national-level Venezuelan electoral processes held during the 1998–2012 period to assess these complaints. The second-digit Benford's law and two statistical models of vote distributions, recently introduced in the literature, are reviewed and used in our case study. In addition, we discuss a new method to detect irregular variations in the electoral roll. The outputs obtained from these election forensic tools are examined taking into account the substantive context of the elections and referenda under study. Thus, we reach two main conclusions. Firstly, all the tools uncover anomalous statistical patterns, which are consistent with election fraud from 2004 onwards. Although our results are not a concluding proof of fraud, they signal the Recall Referendum as a turning point in the integrity of the Venezuelan elections. Secondly, our analysis calls into question the reliability of the electoral register since 2004. In particular, we found irregular variations in the electoral roll that were decisive in winning the 50% majority in the 2004 Referendum and in the 2012 Presidential Elections. PMID:24971462

  10. Forensic analysis of Venezuelan elections during the Chávez presidency.

    PubMed

    Jiménez, Raúl; Hidalgo, Manuel

    2014-01-01

    Hugo Chávez dominated the Venezuelan electoral landscape since his first presidential victory in 1998 until his death in 2013. Nobody doubts that he always received considerable voter support in the numerous elections held during his mandate. However, the integrity of the electoral system has come into question since the 2004 Presidential Recall Referendum. From then on, different sectors of society have systematically alleged electoral irregularities or biases in favor of the incumbent party. We have carried out a thorough forensic analysis of the national-level Venezuelan electoral processes held during the 1998-2012 period to assess these complaints. The second-digit Benford's law and two statistical models of vote distributions, recently introduced in the literature, are reviewed and used in our case study. In addition, we discuss a new method to detect irregular variations in the electoral roll. The outputs obtained from these election forensic tools are examined taking into account the substantive context of the elections and referenda under study. Thus, we reach two main conclusions. Firstly, all the tools uncover anomalous statistical patterns, which are consistent with election fraud from 2004 onwards. Although our results are not a concluding proof of fraud, they signal the Recall Referendum as a turning point in the integrity of the Venezuelan elections. Secondly, our analysis calls into question the reliability of the electoral register since 2004. In particular, we found irregular variations in the electoral roll that were decisive in winning the 50% majority in the 2004 Referendum and in the 2012 Presidential Elections.

  11. [The vaccines based on the replicon of the venezuelan equine encephalomyelitis virus against viral hemorrhagic fevers].

    PubMed

    Petrov, A A; Plekhanova, T M; Sidorova, O N; Borisevich, S V; Makhlay, A A

    2015-01-01

    The status of the various recombinant DNA and RNA-derived candidate vaccines, as well as the Venezuelan equine encephalomyelitis virus (VEEV) replicon vaccine system against extremely hazardous viral hemorrhagic fevers, were reviewed. The VEEV-based replication-incompetent vectors offer attractive features in terms of safety, high expression levels of the heterologous viral antigen, tropism to dendritic cells, robust immune responses, protection efficacy, low potential for pre-existing anti-vector immunity and possibility of engineering multivalent vaccines were tested. These features of the VEEV replicon system hold much promise for the development of new generation vaccine candidates against viral hemorrhagic fevers.

  12. Tectonics of the Argentine and Chilean Andes: An introduction

    NASA Astrophysics Data System (ADS)

    Folguera, Andrés; Alvarado, Patricia; Arriagada, César; Ramos, Victor A.

    2015-12-01

    This Special Issue gathers a series of contributions derived from presentations at the 19° Congreso Geológico Argentino held in Córdoba in 2-6 June 2014. Specific subjects cover a wide variety of topics and regions of the Argentine and Chilean Andes, varying from sedimentological analyses and U/Pb dating of detrital zircons in different rocks to determine source areas for different times and regions along the southern Andes; satellite gravity data for monitoring earthquakes at the subduction zone to understand their complex rupture structure; fission track data from the Andes to the foreland region; use of seismic tomographies and conventional seismic reflection data for analyzing crustal structure; to paleomagnetic data and structural and morphological analyses (Fig. 1).

  13. Spatial diversity patterns of Pristimantis frogs in the Tropical Andes.

    PubMed

    Meza-Joya, Fabio Leonardo; Torres, Mauricio

    2016-04-01

    Although biodiversity gradients have been widely documented, the factors governing broad-scale patterns in species richness are still a source of intense debate and interest in ecology, evolution, and conservation biology. Here, we tested whether spatial hypotheses (species-area effect, topographic heterogeneity, mid-domain null model, and latitudinal effect) explain the pattern of diversity observed along the altitudinal gradient of Andean rain frogs of the genus Pristimantis. We compiled a gamma-diversity database of 378 species of Pristimantis from the tropical Andes, specifically from Colombia to Bolivia, using records collected above 500 m.a.s.l. Analyses were performed at three spatial levels: Tropical Andes as a whole, split in its two main domains (Northern and Central Andes), and split in its 11 main mountain ranges. Species richness, area, and topographic heterogeneity were calculated for each 500-m-width elevational band. Spatial hypotheses were tested using linear regression models. We examined the fit of the observed diversity to the mid-domain hypothesis using randomizations. The species richness of Pristimantis showed a hump-shaped pattern across most of the altitudinal gradients of the Tropical Andes. There was high variability in the relationship between area and species richness along the Tropical Andes. Correcting for area effects had little impact in the shape of the empirical pattern of biodiversity curves. Mid-domain models produced similar gradients in species richness relative to empirical gradients, but the fit varied among mountain ranges. The effect of topographic heterogeneity on species richness varied among mountain ranges. There was a significant negative relationship between latitude and species richness. Our findings suggest that spatial processes partially explain the richness patterns of Pristimantis frogs along the Tropical Andes. Explaining the current patterns of biodiversity in this hot spot may require further studies on

  14. [Relation of fat consumption to colorectal cancer mortality in a Venezuelan population].

    PubMed

    Malavé, H; Méndez Castellano, H; Malavé, I

    1992-06-01

    Epidemiologic and experimental studies have pointed to an association between fat intake and colorectal carcinogenesis. In the present work we have studied the correlation between fat intake and mortality caused by colorectal cancer in the venezuelan population. For this purpose, we have calculated the correlation coefficients between the ingestion of total fat, visible fat (vegetable oil, margarine, butter, mayonnaise) as well as non-visible fat (that contained in other foods) and the mortality rate by colorectal cancer with data from nine venezuelan states and geographical regions. The highest lipid consumption and mortality rates were observed in the more developed states. There was a positive and significant correlation between total as well as visible fat consumption and colorectal cancer mortality (r = 0.756 p < 0.02, and r = 0.958, p < 0.001; respectively). In contrast, there was no significant correlation between the consumption of non visible fats and colorectal mortality (r = 0.543, p < 0.05). More than 80% of the visible fats ingested in Venezuela are constituted by vegetable oil and margarine, which contain a high proportion of polyunsaturated fatty acids. Based on the above, is possible to infer that colorectal carcinogenesis in Venezuela is associated to the uptake of unsaturated fat, and that measures leading to the prevention of this disease should be based on the reduction in the consumption of total and unsaturated lipids.

  15. Translating exercise biology into the Venezuelan medical education and health care system.

    PubMed

    Del Corral, Pedro

    2007-09-01

    In the absence of pharmacological agents, physical exercise was widely used by physicians in the late 19th century to treat a number of maladies. In the 1950's, epidemiological evidence suggested an association between physical activity and health, and increased interest in clinical exercise biology. By the 1990's, sufficient research data was accumulated on the benefits of exercise, such that North American medical associations, government agencies, and the World Health Organization have published guidelines on exercise for public and clinical populations. Despite this, leaders in medical education have remained reluctant to incorporate exercise biology into the core medical curriculum, or to systematically implement it in graduate medical education. This work reviews Venezuelan exercise biology literature, and its medical applications. Venezuelan scientists and clinicians have invested efforts in cardiopulmonary exercise testing, skeletal muscle adaptations to training and exercise cardiovascular pharmacology in patients, sedentary subjects and athletes. It is suggested here, that there is a need to develop education and research programs in basic and clinical exercise biology in the formal training of medical students, physicians in residency programs, and allied health care professionals. Tentative steps to initiate this process are proposed.

  16. Hydrolutos piaroa sp.n. (Orthoptera: Anostostomatidae), a new semiaquatic Lutosini species from south-western Venezuelan lowland streams.

    PubMed

    Derka, Tomáš; Svitok, Marek; Fedor, Peter

    2016-01-01

    Hydrolutos piaroa, a new species of Lutosini (Orthoptera: Anostostomatidae) from Tobogán de la Selva (Puerto Ayacucho region, SW Venezuela) is described and figured. Inhabiting aquatic environment it represents an unusual orthopteran with sternal and pleural area covered by fine microtrichia, forming a plastron. This is the first known Hydrolutos species sampled in lowland streams of Venezuelan Guayana. PMID:27395849

  17. Does glaciation act to limit the topography of active mountain belts? Evidence from the Patagonian Andes

    NASA Astrophysics Data System (ADS)

    Thomson, S. N.

    2003-04-01

    Fission-track thermochronological analysis of the Patagonian Andes of southern Chile, particularly in the region of the major intra-arc Liquiñe-Ofqui transpressional fault zone (42° to 46°S), has revealed a complex pattern of late Cenozoic accelerated cooling. The fault zone has been the focus of localised enhanced cooling, attributed to denudation, since ca. 16 to 10 Ma. Several fault blocks can be identified, differentiated by their different cooling histories and total amounts of late Cenozoic cooling. The transpressional nature of this fault zone implies that enhanced cooling was caused by the preferential erosion of variably uplifting fault blocks that formed part of a large, possibly crustal scale "transpressional flower structure". Despite the spatially variable cooling rates and apparent differential denudation across the different fault blocks, the topography (particularly mean and maximum elevation) across these fault blocks is relatively uniform. This implies that this landscape is close to topographic steady-state, such that denudation has managed to approximately balance transpression related rock uplift, despite the spatial variability of the latter during the late Cenozoic. The most dominant denudation process in the Patagonian Andes is glacial erosion. Late Cenozoic glaciation in Patagonia is well known from studies made on the Patagonian ice fields (the third largest in the World). For example, values for the mean equilibrium line altitude (the altitude where annual glacial accumulation and ablation are the same - roughly equivalent to the snowline) can be cited for both the present day and the last glacial maximum. Incorporating these values in to a quantitative analysis of the topography across the different fault blocks using DEM data supports ideas outlined by Brozovic et al. (1997) who quote that where active mountain belts intersect the snowline, the high rates of glacial erosion processes can act at rates sufficient to place a limit on

  18. Scholarship, Policy, and Personal Development at Northwestern.

    ERIC Educational Resources Information Center

    Leviton, Laura C.

    2003-01-01

    Describes the author's experiences in the evaluation training program at Northwestern University (1978-1980) in a postdoctoral fellowship in methodology and evaluation research. Also discusses the value of the friendships and professional relationships formed at that time. (SLD)

  19. Reflections on Andes' Goal-Free User Interface

    ERIC Educational Resources Information Center

    VanLehn, Kurt

    2016-01-01

    Although the Andes project produced many results over its 18 years of activity, this commentary focuses on its contributions to understanding how a goal-free user interface impacts the overall design and performance of a step-based tutoring system. Whereas a goal-aligned user interface displays relevant goals as blank boxes or empty locations that…

  20. Out of the Andes: patterns of diversification in clearwing butterflies.

    PubMed

    Elias, M; Joron, M; Willmott, K; Silva-Brandão, K L; Kaiser, V; Arias, C F; Gomez Piñerez, L M; Uribe, S; Brower, A V Z; Freitas, A V L; Jiggins, C D

    2009-04-01

    Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species-level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene-Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.

  1. Andes hantavirus variant in rodents, southern Amazon Basin, Peru.

    PubMed

    Razuri, Hugo; Tokarz, Rafal; Ghersi, Bruno M; Salmon-Mulanovich, Gabriela; Guezala, M Claudia; Albujar, Christian; Mendoza, A Patricia; Tinoco, Yeny O; Cruz, Christopher; Silva, Maria; Vasquez, Alicia; Pacheco, Víctor; Ströher, Ute; Guerrero, Lisa Wiggleton; Cannon, Deborah; Nichol, Stuart T; Hirschberg, David L; Lipkin, W Ian; Bausch, Daniel G; Montgomery, Joel M

    2014-02-01

    We investigated hantaviruses in rodents in the southern Amazon Basin of Peru and identified an Andes virus variant from Neacomys spinosus mice. This finding extends the known range of this virus in South America and the range of recognized hantaviruses in Peru. Further studies of the epizoology of hantaviruses in this region are warranted.

  2. Convective initiation in the vicinity of the subtropical Andes

    NASA Astrophysics Data System (ADS)

    Rasmussen, K. L.; Houze, R.

    2014-12-01

    Extreme convection tends to form in the vicinity of mountain ranges, and the Andes in subtropical South America help spawn some of the most intense convection in the world. An investigation of the most intense storms for 11 years of TRMM Precipitation Radar (PR) data shows a tendency for squall lines to initiate and develop in this region with the canonical leading convective line/trailing stratiform structure. The synoptic environment and structures of the extreme convection and MCSs in subtropical South America are similar to those found in other regions of the world, especially the United States. In subtropical South America, however, the topographical influence on the convective initiation and maintenance of the MCSs is unique. A capping inversion in the lee of the Andes is important in preventing premature triggering. The Andes and other mountainous terrain of Argentina focus deep convective initiation in a narrow region. Subsequent to initiation, the convection often evolves into propagating mesoscale convective systems similar to those seen over the Great Plains of the U. S. and produces damaging tornadoes, hail, and floods across a wide agricultural region. Numerical simulations conducted with the NCAR Weather Research and Forecasting (WRF) Model extend the observational analysis and provide an objective evaluation of storm initiation, terrain effects, and development mechanisms. The simulated mesoscale systems closely resemble the storm structures seen by the TRMM Precipitation Radar as well as the overall shape and character of the storms shown in GOES satellite data. A sensitivity experiment with different configurations of topography, including both decreasing and increasing the height of the Andes Mountains, provides insight into the significant influence of orography in focusing convective initiation in this region. Lee cyclogenesis and a strong low-level jet are modulated by the height of the Andes Mountains and directly affect the character

  3. Stable oxygen isotopes (delta18(O)) in Austrocedrus chilensis tree rings reflect climate variability in northwestern Patagonia, Argentina.

    PubMed

    Roig, F A; Siegwolf, R; Boninsegna, J A

    2006-11-01

    The stable oxygen isotope (delta (18)O) composition of Austrocedrus chilensis (D. Don) Endl. (Cupressaceae) tree rings potentially provide retrospective views of changes in environment and climate in the semi-arid lands of Patagonia. We report the development of the first annually resolved delta (18)O tree-ring chronology obtained from natural forests of the foothills of the northwestern Patagonian Andes. The isotope record spans between 1890 and 1994 AD. We explore the probable links between this record and the climate of the region. Air temperatures during summer conditions are significantly, but not strongly, inversely correlated with annual delta (18)O values from Austrocedrus tree rings. The strongest correlations are between the southern oscillation index (SOI) and the tree rings. The existence of millennial-age Austrocedrus trees in northern Patagonia provides interesting possibilities for examining these climate-related isotopic signals over most of the last 1,000 years.

  4. Thermophilization of adult and juvenile tree communities in the northern tropical Andes.

    PubMed

    Duque, Alvaro; Stevenson, Pablo R; Feeley, Kenneth J

    2015-08-25

    Climate change is expected to cause shifts in the composition of tropical montane forests towards increased relative abundances of species whose ranges were previously centered at lower, hotter elevations. To investigate this process of "thermophilization," we analyzed patterns of compositional change over the last decade using recensus data from a network of 16 adult and juvenile tree plots in the tropical forests of northern Andes Mountains and adjacent lowlands in northwestern Colombia. Analyses show evidence that tree species composition is strongly linked to temperature and that composition is changing directionally through time, potentially in response to climate change and increasing temperatures. Mean rates of thermophilization [thermal migration rate (TMR), °C ⋅ y(-1)] across all censuses were 0.011 °C ⋅ y(-1) (95% confidence interval = 0.002-0.022 °C ⋅ y(-1)) for adult trees and 0.027 °C ⋅ y(-1) (95% confidence interval = 0.009-0.050 °C ⋅ y(-1)) for juvenile trees. The fact that thermophilization is occurring in both the adult and juvenile trees and at rates consistent with concurrent warming supports the hypothesis that the observed compositional changes are part of a long-term process, such as global warming, and are not a response to any single episodic event. The observed changes in composition were driven primarily by patterns of tree mortality, indicating that the changes in composition are mostly via range retractions, rather than range shifts or expansions. These results all indicate that tropical forests are being strongly affected by climate change and suggest that many species will be at elevated risk for extinction as warming continues.

  5. Thermophilization of adult and juvenile tree communities in the northern tropical Andes

    PubMed Central

    Duque, Alvaro; Stevenson, Pablo R.; Feeley, Kenneth J.

    2015-01-01

    Climate change is expected to cause shifts in the composition of tropical montane forests towards increased relative abundances of species whose ranges were previously centered at lower, hotter elevations. To investigate this process of “thermophilization,” we analyzed patterns of compositional change over the last decade using recensus data from a network of 16 adult and juvenile tree plots in the tropical forests of northern Andes Mountains and adjacent lowlands in northwestern Colombia. Analyses show evidence that tree species composition is strongly linked to temperature and that composition is changing directionally through time, potentially in response to climate change and increasing temperatures. Mean rates of thermophilization [thermal migration rate (TMR), °C⋅y−1] across all censuses were 0.011 °C⋅y−1 (95% confidence interval = 0.002–0.022 °C⋅y−1) for adult trees and 0.027 °C⋅y−1 (95% confidence interval = 0.009–0.050 °C⋅y−1) for juvenile trees. The fact that thermophilization is occurring in both the adult and juvenile trees and at rates consistent with concurrent warming supports the hypothesis that the observed compositional changes are part of a long-term process, such as global warming, and are not a response to any single episodic event. The observed changes in composition were driven primarily by patterns of tree mortality, indicating that the changes in composition are mostly via range retractions, rather than range shifts or expansions. These results all indicate that tropical forests are being strongly affected by climate change and suggest that many species will be at elevated risk for extinction as warming continues. PMID:26261350

  6. Thermophilization of adult and juvenile tree communities in the northern tropical Andes.

    PubMed

    Duque, Alvaro; Stevenson, Pablo R; Feeley, Kenneth J

    2015-08-25

    Climate change is expected to cause shifts in the composition of tropical montane forests towards increased relative abundances of species whose ranges were previously centered at lower, hotter elevations. To investigate this process of "thermophilization," we analyzed patterns of compositional change over the last decade using recensus data from a network of 16 adult and juvenile tree plots in the tropical forests of northern Andes Mountains and adjacent lowlands in northwestern Colombia. Analyses show evidence that tree species composition is strongly linked to temperature and that composition is changing directionally through time, potentially in response to climate change and increasing temperatures. Mean rates of thermophilization [thermal migration rate (TMR), °C ⋅ y(-1)] across all censuses were 0.011 °C ⋅ y(-1) (95% confidence interval = 0.002-0.022 °C ⋅ y(-1)) for adult trees and 0.027 °C ⋅ y(-1) (95% confidence interval = 0.009-0.050 °C ⋅ y(-1)) for juvenile trees. The fact that thermophilization is occurring in both the adult and juvenile trees and at rates consistent with concurrent warming supports the hypothesis that the observed compositional changes are part of a long-term process, such as global warming, and are not a response to any single episodic event. The observed changes in composition were driven primarily by patterns of tree mortality, indicating that the changes in composition are mostly via range retractions, rather than range shifts or expansions. These results all indicate that tropical forests are being strongly affected by climate change and suggest that many species will be at elevated risk for extinction as warming continues. PMID:26261350

  7. Venezuelan equine encephalitis in Panama: fatal endemic disease and genetic diversity of etiologic viral strains.

    PubMed

    Quiroz, Evelia; Aguilar, Patricia V; Cisneros, Julio; Tesh, Robert B; Weaver, Scott C

    2009-06-30

    Venezuelan equine encephalitis (VEE) is a reemerging, mosquito-borne viral disease of the neotropics that is severely debilitating and sometimes fatal to humans. Periodic epidemics mediated by equine amplification have been recognized since the 1920s, but interepidemic disease is rarely recognized. We report here clinical findings and genetic characterization of 42 cases of endemic VEE detected in Panama from 1961-2004. Recent clusters of cases occurred in Darien (eastern Panama) and Panama provinces (central Panama) near rainforest and swamp habitats. Patients ranged from 10 months to 48 years of age, and the more severe cases with neurological complications, including one fatal infection, were observed in children. The VEE virus strains isolated from these cases all belonged to an enzootic, subtype ID lineage known to circulate among sylvatic vectors and rodent reservoir hosts in Panama and Peru. These findings underscore endemic VEE as an important but usually neglected arboviral disease of Latin America.

  8. IRES-Containing VEEV Vaccine Protects Cynomolgus Macaques from IE Venezuelan Equine Encephalitis Virus Aerosol Challenge

    PubMed Central

    Rossi, Shannan L.; Russell-Lodrigue, Kasi E.; Killeen, Stephanie Z.; Wang, Eryu; Leal, Grace; Bergren, Nicholas A.; Vinet-Oliphant, Heather; Weaver, Scott C.; Roy, Chad J.

    2015-01-01

    Venezuelan equine encephalitis virus (VEEV) is an arbovirus endemic to the Americas that is responsible for severe, sometimes fatal, disease in humans and horses. We previously described an IRES-based VEE vaccine candidate based up the IE serotype that offers complete protection against a lethal subtype IE VEEV challenge in mice. Here we demonstrate the IRES-based vaccine’s ability to protect against febrile disease in cynomolgus macaques. Vaccination was well tolerated and elicited robust neutralizing antibody titers noticed as early as day 14. Moreover, complete protection from disease characterized by absence of viremia and characteristic fever following aerosolized IE VEEV challenge was observed in all vaccinees compared to control animals, which developed clinical disease. Together, these results highlight the safety and efficacy of IRES-based VEEV vaccine to protect against an endemic, pathogenic VEEV IE serotype. PMID:26020513

  9. Chikungunya fever: Atypical and lethal cases in the Western hemisphere: A Venezuelan experience.

    PubMed

    Torres, Jaime R; Leopoldo Códova G; Castro, Julio S; Rodríguez, Libsen; Saravia, Víctor; Arvelaez, Joanne; Ríos-Fabra, Antonio; Longhi, María A; Marcano, Melania

    2015-01-01

    A large epidemic of Chikungunya fever currently affects the Caribbean, Central and South America. Despite a high number of reported cases, little is known on the occurrence of severe clinical complications. We describe four Venezuelan patients with a severe and/or lethal course who exhibit unusual manifestations of the disease. Case 1 describes a 75 year-old man with rapid onset of septic shock and multi-organ failure. Cases 2 and 3 describe two patients with rapid aggressive clinical course who developed shock, severe purpuric lesions and a distinct area large of necrosis in the nasal region. Case 4 depicts a splenectomized woman with shock, generalized purpuric lesions, bullous dermatosis and acronecrosis of an upper limb. Chikungunya fever in the Western hemisphere may also associate with atypical and severe manifestations. Some patients experience a life-threatening, aggressive clinical course, with rapid deterioration and death due to multisystem failure.

  10. Primary immunoglobulin response of herons to infection with Venezuelan encephalitis virus.

    PubMed

    Powers, C D; Dickerman, R W

    1975-02-01

    Seven to nine days after inoculation with a replicating antigen, Venezuelan encephalitis virus, hemagglutination-inhibiting antibodies were present in plasma of 18 to 20 black-crowned night herons (BCNH), 14 of 15 great egrets (ge) , and 7 of 7 snowy egrets (SE). 19S (immunoglobulin M) precedes 7S (immunoglobulin G) antibodies in all but one bird of six GE, six SE, and six BCNH. 19S antibodies were detected for only 2 to 4 weeks post-inoculation. The induction period for both types of antibody was prolonged by 2 to 6 days as compared with earlier studies in gallinaceous birds using nonreplicating antigens. A marked delay in reaching peak titer of 7S antibodies was also observed. Hemagglutination inhibition tests were nearly as sensitive as neutralization tests for detecting 19S and early 7S antibodies. Size of virus inoculum did not measurably affect time of induction or titer of antibodies.

  11. Venezuelan Equine Encephalitis in Panama: Fatal Endemic Disease and Genetic Diversity of Etiologic Viral Strains

    PubMed Central

    Quiroz, Evelia; Aguilar, Patricia V.; Cisneros, Julio; Tesh, Robert B.; Weaver, Scott C.

    2009-01-01

    Venezuelan equine encephalitis (VEE) is a reemerging, mosquito-borne viral disease of the neotropics that is severely debilitating and sometimes fatal to humans. Periodic epidemics mediated by equine amplification have been recognized since the 1920s, but interepidemic disease is rarely recognized. We report here clinical findings and genetic characterization of 42 cases of endemic VEE detected in Panama from 1961–2004. Recent clusters of cases occurred in Darien (eastern Panama) and Panama provinces (central Panama) near rainforest and swamp habitats. Patients ranged from 10 months to 48 years of age, and the more severe cases with neurological complications, including one fatal infection, were observed in children. The VEE virus strains isolated from these cases all belonged to an enzootic, subtype ID lineage known to circulate among sylvatic vectors and rodent reservoir hosts in Panama and Peru. These findings underscore endemic VEE as an important but usually neglected arboviral disease of Latin America. PMID:19564908

  12. [Smith-Lemli-Opitz syndrome and hypothyroidism: the first Venezuelan case].

    PubMed

    Lima-Martínez, Marcos M; Zerpa, José; Gil, Victor

    2014-09-01

    The Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive metabolic disorder due to an abnormal cholesterol synthesis. It was first described by Smith, Lemli and Opitz in 1964. Many cases of SLOS have been described since then, leading to the recognition as a relatively common malformation syndrome. Affected individuals have dysmorphism, microcephaly, multiple congenital malformations, mental retardation, aggressiveness and hyperactivity. The severity of physical defects correlates with the severity of the cholesterol deficiency, which is caused by an abnormally low activity of 7-dehydrocholesterol reductase, the enzyme responsible for conversion of 7-dehydrocholesterol to cholesterol. The occurrence of hypothyroidism in association with SLOS is very unusual. We describe the first Venezuelan case in which both anomalies are associated. PMID:25272525

  13. Structural and biophysical analysis of sequence insertions in the Venezuelan Equine Encephalitis Virus macro domain.

    PubMed

    Guillén, Jaime; Lichière, Julie; Rabah, Nadia; Beitzel, Brett F; Canard, Bruno; Coutard, Bruno

    2015-04-01

    Random transposon insertions in viral genomes can be used to reveal genomic regions important for virus replication. We used these genomic data to evaluate at the protein level the effect of such insertions on the Venezuelan Equine Encephalitis Virus nsP3 macro domain. The structural analysis showed that transposon insertions occur mainly in loops connecting the secondary structure elements. Some of the insertions leading to a temperature sensitive viral phenotype (ts) are close to the cleavage site between nsP2 and nsP3 or the ADP-ribose binding site, two important functions of the macro domain. Using four mutants mimicking the transposon insertions, we confirmed that these insertions can affect the macro domain properties without disrupting the overall structure of the protein.

  14. Chikungunya fever: Atypical and lethal cases in the Western hemisphere: A Venezuelan experience.

    PubMed

    Torres, Jaime R; Leopoldo Códova G; Castro, Julio S; Rodríguez, Libsen; Saravia, Víctor; Arvelaez, Joanne; Ríos-Fabra, Antonio; Longhi, María A; Marcano, Melania

    2015-01-01

    A large epidemic of Chikungunya fever currently affects the Caribbean, Central and South America. Despite a high number of reported cases, little is known on the occurrence of severe clinical complications. We describe four Venezuelan patients with a severe and/or lethal course who exhibit unusual manifestations of the disease. Case 1 describes a 75 year-old man with rapid onset of septic shock and multi-organ failure. Cases 2 and 3 describe two patients with rapid aggressive clinical course who developed shock, severe purpuric lesions and a distinct area large of necrosis in the nasal region. Case 4 depicts a splenectomized woman with shock, generalized purpuric lesions, bullous dermatosis and acronecrosis of an upper limb. Chikungunya fever in the Western hemisphere may also associate with atypical and severe manifestations. Some patients experience a life-threatening, aggressive clinical course, with rapid deterioration and death due to multisystem failure. PMID:26793440

  15. NRAMP1 and VDR Gene Polymorphisms in Susceptibility to Tuberculosis in Venezuelan Population

    PubMed Central

    Fernández-Mestre, Mercedes; Villasmil, Ángel; Takiff, Howard; Fuentes Alcalá, Zhenia

    2015-01-01

    Natural resistance-associated macrophage protein (Nramp1) and the vitamin D receptor (VDR) are central components of the innate and adaptive immunity against Mycobacterium tuberculosis, and associations between susceptibility to tuberculosis and polymorphisms in the genes NRAMP and VDR have been sought in geographically diverse populations. We investigated associations of NRAMP1 and VDR gene polymorphisms with susceptibility to TB in the Venezuelan population. The results suggest the absence of any association between VDR variants FokI, ApaI, and TaqI and susceptibility to tuberculosis. In contrast, the NRAMP1 3′UTR variants were associated with susceptibility to M. tuberculosis infection, as seen in the comparisons between TST+ and TST− controls, and also with progression to TB disease, as shown in the comparisons between TB patients and TST+ controls. This study confirms the previously described association of the NRAMP1 3′UTR polymorphism with M. tuberculosis infection and disease progression. PMID:26578819

  16. Structural and biophysical analysis of sequence insertions in the Venezuelan Equine Encephalitis Virus macro domain.

    PubMed

    Guillén, Jaime; Lichière, Julie; Rabah, Nadia; Beitzel, Brett F; Canard, Bruno; Coutard, Bruno

    2015-04-01

    Random transposon insertions in viral genomes can be used to reveal genomic regions important for virus replication. We used these genomic data to evaluate at the protein level the effect of such insertions on the Venezuelan Equine Encephalitis Virus nsP3 macro domain. The structural analysis showed that transposon insertions occur mainly in loops connecting the secondary structure elements. Some of the insertions leading to a temperature sensitive viral phenotype (ts) are close to the cleavage site between nsP2 and nsP3 or the ADP-ribose binding site, two important functions of the macro domain. Using four mutants mimicking the transposon insertions, we confirmed that these insertions can affect the macro domain properties without disrupting the overall structure of the protein. PMID:25725151

  17. Intraoral minor salivary gland tumors: a retrospective study of 62 cases in a Venezuelan population.

    PubMed

    Rivera-Bastidas, H; Ocanto, R A; Acevedo, A M

    1996-01-01

    From 1968 to 1992 sixty-two cases of tumors of minor salivary glands were diagnosed from a Venezuelan population at the Oral Histopathology Laboratory of the Central University of Venezuela School of Dentistry. The diagnosis of individual tumors was based on the 1991 World Health Organization classification. Tumors were analyzed considering histological type, age and sex of the patient, and intraoral location. Pleomorphic adenomas constituted the most common histological diagnosis of the benign sample (71%), and 62% of the malignant tumors were diagnosed as mucoepidermoid carcinomas. The principal location was the palate, and a marked female prevalence was observed. Geographic differences appear to exist when compared with results of studies representing a cross-section of different world population groups.

  18. [Effect of noise on blood pressure in workers of a Venezuelan oil company].

    PubMed

    Fernández-D' Pool, Janice; Butrón, Jorge; Colina-Chourio, José

    2010-09-01

    Occupational noise has been related to cardiovascular events, although epidemiologically, there is not a clear explanation. To determine the development of arterial hypertension in workers exposed to a noise level higher than 85 dB (A) and to relate it with the working place, labor antiquity and the use of auditive protection, a case-control study was done in a Venezuelan oil company. Fifty working men, that fulfilled the inclusion and exclusion criteria, were included in each group. The information was obtained from the occupational clinical history, based on international guidelines, to evaluate the parameters of the study, The intensity of environmental noise was obtained according to recommended Venezuelan "Norma COVENIN 1565-95". The mean age of cases and controls were 39 +/- 0.06 and 44 +/- 0.44 years old respectively; the labor seniority was similar in both groups; 22 an 48% of cases and controls respectively had a family history of arterial hypertension (p<0.05), without a high significant prevalence in both groups. In both groups we observed overweight. In 92% of cases and 80% of controls there were normal levels of glucose (p<0.01); 68 and 84% of cases and controls, respectively, presented alterations of the lipid levels (p<0.05). The measurements of environmental noise registered levels that exceeded 85 dB (A), being the mean 87.78 +/- 1.10 dB (A); 94% of the cases used hearing protective equipment and 60% of them presented arterial hypertension and 80% of those that did not used it, showed arterial hypertension. There was not a significant relationship among the auditive loss induced by occupational noise, its intensity and labor seniority with the prevalence of arterial hypertension. We cannot conclude that occupational noise is a decisive factor in the development of arterial hypertension in noise exposed workers.

  19. Synchronous interhemispheric Holocene climate trends in the tropical Andes.

    PubMed

    Polissar, Pratigya J; Abbott, Mark B; Wolfe, Alexander P; Vuille, Mathias; Bezada, Maximiliano

    2013-09-01

    Holocene variations of tropical moisture balance have been ascribed to orbitally forced changes in solar insolation. If this model is correct, millennial-scale climate evolution should be antiphased between the northern and southern hemispheres, producing humid intervals in one hemisphere matched to aridity in the other. Here we show that Holocene climate trends were largely synchronous and in the same direction in the northern and southern hemisphere outer-tropical Andes, providing little support for the dominant role of insolation forcing in these regions. Today, sea-surface temperatures in the equatorial Pacific Ocean modulate rainfall variability in the outer tropical Andes of both hemispheres, and we suggest that this mechanism was pervasive throughout the Holocene. Our findings imply that oceanic forcing plays a larger role in regional South American climate than previously suspected, and that Pacific sea-surface temperatures have the capacity to induce abrupt and sustained shifts in Andean climate. PMID:23959896

  20. First human isolate of Hantavirus (Andes virus) in the Americas.

    PubMed

    Galeno, Hector; Mora, Judith; Villagra, Eliecer; Fernandez, Jorge; Hernandez, Jury; Mertz, Gregory J; Ramirez, Eugenio

    2002-07-01

    We isolated Andes virus (formal name: Andes virus [ANDV], a species in the genus Hantavirus), from serum of an asymptomatic 10-year-old Chilean boy who died 6 days later of hantavirus pulmonary syndrome (HPS). The serum was obtained 12 days after his grandmother died from HPS and 2 days before he became febrile. No hantavirus immunoglobulin (Ig) G or IgM antibodies were detected in the serum sample. After three blind passages, ANDV antigens were detected in Vero E6 cells by immunofluorescence assay and enzyme-linked immunosorbent assay, and ANDV RNA was detected by reverse transcription-polymerase chain reaction. A fragment of the virus genome showed 96.2% nucleotide identity with that of prototype ANDV. To our knowledge, this is the first isolation of any agent of hemorrhagic fever with HPS from a human and the first such isolation of hantavirus before symptoms of that syndrome or HPS began.

  1. First GPS baseline results from the North Andes

    NASA Technical Reports Server (NTRS)

    Kellogg, James N.; Freymueller, Jeffrey T.; Dixon, Timothy H.; Neilan, Ruth E.; Ropain, Clemente

    1990-01-01

    The CASA Uno GPS experiment (January-February 1988) has provided the first epoch baseline measurements for the study of plate motions and crustal deformation in and around the North Andes. Two dimensional horizontal baseline repeatabilities are as good as 5 parts in 10 to the 8th for short baselines (100-1000 km), and better than 3 parts in 10 to the 8th for long baselines (greater than 1000 km). Vertical repeatabilities are typically 4-6 cm, with a weak dependence on baseline length. The expected rate of plate convergence across the Colombia Trench is 6-8cm/yr, which should be detectable by the repeat experiment planned for 1991. Expected deformation rates within the North Andes are of the order of 1 cm/yr, which may be detectable with the 1991 experiment.

  2. Glacier shrinkage and water resources in the Andes

    NASA Astrophysics Data System (ADS)

    Francou, Bernard; Coudrain, Anne

    For more than a century glaciers around the world have been melting as air temperatures rise due to a combination of natural processes and human activity. The disappearance of these glaciers can have wide-ranging effects, such as the creation of new natural hazards or changes in stream flow that could threaten water suppliesSome of the most dramatic melting has occurred in the Andes mountain range in South America. To highlight the climatic and glacial change in the Andes and to encourage the scientific community to strengthen the glacier observation network that stretches from Colombia to the Patagonian ice fields, the Instituto Nacional de Recursos Naturales (INRENA), Perú, and the Institute of Research and Development (IRD), France, recently organized the second Symposium on Mass Balance of Andean Glaciers in Huaráz,Perú.

  3. Epochs of intrusion-related copper mineralization in the Andes

    NASA Astrophysics Data System (ADS)

    Sillitoe, R. H.

    Seventy-four copper deposits and prospects related intimately to intrusive activity in the Andes have been dated radiometrically during the last 18 years by many different investigators, most of whom used the KAr method. The results are summarized and some of their local and regional implications are reviewed. A number of copper deposits, mainly of the porphyry type, were emplaced in, or near to, premineral volcanic sequences and (or) equigranular plutons. Such precursor volcanism lasted for as long as 9 Ma, and preceded mineralization by intervals of from less than 1 Ma to as much as 9 Ma. Precursor plutons were emplaced no more than 2 to 3 Ma prior to mineralization at several localities in Chile, but possibly as long as 10 to 30 Ma earlier in parts of Colombia and Peru. The time separating emplacement of progenitor stocks and hydrothermal alteration and accompanying copper mineralization, and the duration of alteration-mineralization sequences generally are both less than the analytical uncertainty of the KAr method. However, on the basis of a detailed study of the Julcani vein system in Peru and less clearcut evidence from elsewhere, it may be concluded that alteration and copper mineralization followed stock or dome emplacement by substantially less than 1 Ma and lasted for 0.5 to 2 Ma and, locally, possibly as long as 3 Ma. At several localities, post-mineral magmatic activity could not be separated by the KAr method from the preceding alteration-mineralization events. As many as nine epochs of copper mineralization, ranging in age from late Paleozoic to late Pliocene-Pleistocene, are recognizable in the central Andes of Chile, Peru, Bolivia, and Argentina, and at least four somewhat different epochs characterize the northern Andes of Colombia. Each epoch coincides with a discrete linear sub-belt, some of which extend for more than 2000 km along the length of the orogen. More than 90% of Andean copper resources, mainly as porphyry deposits, are

  4. Synchronous interhemispheric Holocene climate trends in the tropical Andes

    PubMed Central

    Polissar, Pratigya J.; Abbott, Mark B.; Wolfe, Alexander P.; Vuille, Mathias; Bezada, Maximiliano

    2013-01-01

    Holocene variations of tropical moisture balance have been ascribed to orbitally forced changes in solar insolation. If this model is correct, millennial-scale climate evolution should be antiphased between the northern and southern hemispheres, producing humid intervals in one hemisphere matched to aridity in the other. Here we show that Holocene climate trends were largely synchronous and in the same direction in the northern and southern hemisphere outer-tropical Andes, providing little support for the dominant role of insolation forcing in these regions. Today, sea-surface temperatures in the equatorial Pacific Ocean modulate rainfall variability in the outer tropical Andes of both hemispheres, and we suggest that this mechanism was pervasive throughout the Holocene. Our findings imply that oceanic forcing plays a larger role in regional South American climate than previously suspected, and that Pacific sea-surface temperatures have the capacity to induce abrupt and sustained shifts in Andean climate. PMID:23959896

  5. Venezuelan oil

    SciTech Connect

    Martinez, A.R. )

    1989-01-01

    Oil reserves have been known to exist in Venezuela since early historical records, however, it was not until the 20th century that the extensive search for new reserves began. The 1950's marked the height of oil exploration when 200 new oil fields were discovered, as well as over 60{percent} of proven reserves. Venezuela now produces one tone in seven of crude oil consumption and the country's abundant reserves such as the Bolivar Coastal field in the West of the country and the Orinoco Belt field in the East, will ensure it's continuing importance as an oil producer well into the 21st century. This book charts the historical development of Venezuela oil and provides a chronology of all the significant events which have shaped the oil industry of today. It covers all the technical, legal, economic and political factors which have contributed to the evolution of the industry and also gives information on current oil resources and production. Those events significant to the development of the industry, those which were influential in shaping future policy and those which precipitated further action are included. The book provides a source of reference to oil companies, oil economists and petroleum geologists.

  6. Crustal-thickness variations in the central Andes

    SciTech Connect

    Beck, S.L.; Myers, S.C.; Wallace, T.C.; Zandt, G. |; Silver, P.G.; Drake, L.

    1996-05-01

    We estimated the crustal thickness along an east-west transect across the Andes at lat 20{degree}S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). We found crustal-thickness variations of nearly 40 km across the Andes. Maximum crustal thicknesses of 70-74 km under the Western Cordillera and the Eastern Cordillera thin to 32-38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20{degree}S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16{degree}S, 55-60 km) to south (20{degree}S, 70-74 km) along the Eastern Cordillera. The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation. In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere. With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton. 26 refs., 4 figs.

  7. High Altiplano of the Andes, Chile and Argentina

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The dry desert climate of the high Altiplano of the South american Andes (27.0S, 68.5W) presents a stark landscape of lava flows from many extinct volcanoes and salars (dry lakebeds). Wind streaks across the surface are the result of strong prevailing WNW winds picking up fine particles of salt and volcanic ash, transporting it eastward. The small lakes in some of the basins have different colors because of varying salinity and algae activity.

  8. Crustal-thickness variations in the central Andes

    NASA Astrophysics Data System (ADS)

    Beck, Susan L.; Zandt, George; Myers, Stephen C.; Wallace, Terry C.; Silver, Paul G.; Drake, Lawrence

    1996-05-01

    We estimated the crustal thickness along an east-west transect across the Andes at lat 20°S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). Waveforms of deep regional events in the downgoing Nazca slab and teleseismic earthquakes were processed to isolate the P-to-S converted phases from the Moho in order to compute the crustal thickness. We found crustal-thickness variations of nearly 40 km across the Andes. Maximum crustal thicknesses of 70 74 km under the Western Cordillera and the Eastern Cordillera thin to 32 38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20°S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16°S, 55 60 km) to south (20°S, 70 74 km) along the Eastern Cordillera. The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation. In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere. With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton.

  9. Glaciers in Southern Andes seen from STS-63 Discovery

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Glaciers in the Andes Mountains jut into two lakes in the Patagoinian lowlands. Lago Viedman appears at center in the top portion of the 70mm frame. Lago Argentina barely appears in the frame at far right. The glaciers descend from the very high and wet mountains of southern Chile (peaks reach 3,600 meters) in a range locally known as Cordillera Darwin. The lakes in the picture were carved out by the glaciers during advances of the ice.

  10. A review of the geology of the Argentinian Fuegian Andes

    NASA Astrophysics Data System (ADS)

    Olivero, Eduardo B.; Martinioni, Daniel R.

    2001-06-01

    Seven stratigraphic units reflect the tectonic evolution of the Argentinian Fuegian Andes: Basement (Paleozoic-Jurassic); Lemaire Formation (Upper Jurassic); Yahgan-Beauvoir formations (Lower Cretaceous); Cerro Matrero Formation (Upper Cretaceous); Rı´o Claro Formation (Paleocene); La Despedida Group (Eocene); and Cabo Peña Formation (uppermost Eocene-Lower Oligocene). Basement rocks (garnet, quartz-sericite, and chlorite schists; and amphibolites) are unconformably covered by the Lemaire Formation (rhyolites; basalts; slates; and acidic volcaniclastic breccias, tuffs, conglomerates, and turbidites), formed during extensional tectonism. The post-rift Yahgan Formation (deep-marine black mudstones, andesitic volcaniclastic turbidites and tuffs) interfingers northward with the Beauvoir Formation (slope and platform black mudstones), and covers the Lemaire Formation unconformably. The Yahgan Formation represents an andesitic, volcaniclastic apron, coeval with a Pacific volcanic-arc, filling a marginal basin floored with oceanic crust. The Late Cretaceous compressional orogeny resulted in tectonic inversion, closure of the marginal basin, peak metamorphism and folding, and initial uplifting of the Fuegian Andes. By the latest Cretaceous-earliest Paleogene, the Andes were exposed to subaerial erosion, and the lowest Danian Rı´o Claro Formation bears clear evidence of an Andean clastic provenance. The Rı´o Claro Formation represents the first molasse deposits of the foreland stage of evolution of the Fuegian Andes. Earliest Paleogene north-verging thrust propagation deformed the Rı´o Claro Formation and older units, producing northward depocenter migration. La Despedida Group rests unconformably on the Rı´o Claro Formation and is involved in the thrust and fold belt. Important Eocene compression resulted in thrusting of central Andean basement schists and the Lemaire Formation over Lower Cretaceous and continental Paleogene rocks, respectively. In the

  11. Late Cenozoic Exhumation in the Northern Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Michalak, M.; Hall, S. R.; Farber, D.; Hourigan, J. K.

    2011-12-01

    Orogens represent first-order morphological manifestations of the dynamical forces that drive plate tectonics. Despite advances in techniques that quantify geologic processes, understanding these processes at a continental scale remains challenging. The South American Andes are an example of a long-lived, morphologically and tectonically segmented orogen. The Northern Peruvian Andes are characterized by flat slab subduction and a relatively narrow section of high topography, in contrast to the central Andes, which contain the broad Altiplano-Puna plateau and normal-angle subduction. Current models of Andean orogenesis suggest that most of the high topography evolved recently beginning about 10-20Ma. Recent data from the Central Andes further suggest that this uplift occurred rapidly from ~6-10Ma. However, as many of these data are from the central Andean region, they may not be directly applicable to the entire Andean chain. Therefore, it is critical to investigate areas outside of the central Andean region using similar techniques to test the applicability of these models elsewhere in the Andes. Here, we use low-temperature thermochronology to characterize the shallow crustal cooling history from four sites in the northern Peruvian Andes, across three degrees of latitude (5°S to 8°S). By using both apatite and zircon (U-Th)/He thermochronometers we are able to record rates of crustal exhumation as well as temporal and spatial accelerations and decelerations of exhumation. In contrast to previous studies based on stratigraphical, structural and sedimentological relationships, our preliminary results show no significant exhumation until the Miocene in the Eastern Cordillera of Northern Peru. In general, our results indicate slow exhumation (<0.01 mm/yr) during the Mesozoic and early Cenozoic and record an acceleration of exhumation in the late Miocene to the present, to rates of 0.2-0.5 mm/yr. This regional acceleration signal occurs in field sites in the north (5

  12. Spontaneously Settled Refugees in Northwestern Province, Zambia.

    ERIC Educational Resources Information Center

    Freund, Paul J.; Kalumba, Katele

    1986-01-01

    Presents results of a socioeconomic survey and census of "spontaneously settled" Zairean and Angolan refugees in the Northwestern Province of Zambia. Finds refugees' difficulties to be caused by lack of a clear national policy and negative attitudes toward them, as well as Zambia's own deteriorating economic situation. (GC)

  13. Venezuelan Equine Encephalitis Virus Variants Lacking Transcription Inhibitory Functions Demonstrate Highly Attenuated Phenotype

    PubMed Central

    Atasheva, Svetlana; Kim, Dal Young; Frolova, Elena I.

    2014-01-01

    ABSTRACT Alphaviruses represent a significant public health threat worldwide. They are transmitted by mosquitoes and cause a variety of human diseases ranging from severe meningoencephalitis to polyarthritis. To date, no efficient and safe vaccines have been developed against any alphavirus infection. However, in recent years, significant progress has been made in understanding the mechanism of alphavirus replication and virus-host interactions. These data have provided the possibility for the development of new rationally designed alphavirus vaccine candidates that combine efficient immunogenicity, high safety, and inability to revert to pathogenic phenotype. New attenuated variants of Venezuelan equine encephalitis virus (VEEV) designed in this study combine a variety of characteristics that independently contribute to a reduction in virulence. These constructs encode a noncytopathic VEEV capsid protein that is incapable of interfering with the innate immune response. The capsid-specific mutations strongly affect neurovirulence of the virus. In other constructs, they were combined with changes in control of capsid translation and an extensively mutated packaging signal. These modifications also affected the residual neurovirulence of the virus, but it remained immunogenic, and a single immunization protected mice against subsequent infection with epizootic VEEV. Similar approaches of attenuation can be applied to other encephalitogenic New World alphaviruses. IMPORTANCE Venezuelan equine encephalitis virus (VEEV) is an important human and animal pathogen, which causes periodic outbreaks of highly debilitating disease. Despite a continuous public health threat, no safe and efficient vaccine candidates have been developed to date. In this study, we applied accumulated knowledge about the mechanism of VEEV replication, RNA packaging, and interaction with the host to design new VEEV vaccine candidates that demonstrate exceptionally high levels of safety due to a

  14. Venezuelan Equine Encephalitis Virus Induces Apoptosis through the Unfolded Protein Response Activation of EGR1

    PubMed Central

    Baer, Alan; Lundberg, Lindsay; Swales, Danielle; Waybright, Nicole; Pinkham, Chelsea; Dinman, Jonathan D.

    2016-01-01

    ABSTRACT Venezuelan equine encephalitis virus (VEEV) is a previously weaponized arthropod-borne virus responsible for causing acute and fatal encephalitis in animal and human hosts. The increased circulation and spread in the Americas of VEEV and other encephalitic arboviruses, such as eastern equine encephalitis virus and West Nile virus, underscore the need for research aimed at characterizing the pathogenesis of viral encephalomyelitis for the development of novel medical countermeasures. The host-pathogen dynamics of VEEV Trinidad donkey-infected human astrocytoma U87MG cells were determined by carrying out RNA sequencing (RNA-Seq) of poly(A) and mRNAs. To identify the critical alterations that take place in the host transcriptome following VEEV infection, samples were collected at 4, 8, and 16 h postinfection and RNA-Seq data were acquired using an Ion Torrent PGM platform. Differential expression of interferon response, stress response factors, and components of the unfolded protein response (UPR) was observed. The protein kinase RNA-like endoplasmic reticulum kinase (PERK) arm of the UPR was activated, as the expression of both activating transcription factor 4 (ATF4) and CHOP (DDIT3), critical regulators of the pathway, was altered after infection. Expression of the transcription factor early growth response 1 (EGR1) was induced in a PERK-dependent manner. EGR1−/− mouse embryonic fibroblasts (MEFs) demonstrated lower susceptibility to VEEV-induced cell death than isogenic wild-type MEFs, indicating that EGR1 modulates proapoptotic pathways following VEEV infection. The influence of EGR1 is of great importance, as neuronal damage can lead to long-term sequelae in individuals who have survived VEEV infection. IMPORTANCE Alphaviruses represent a group of clinically relevant viruses transmitted by mosquitoes to humans. In severe cases, viral spread targets neuronal tissue, resulting in significant and life-threatening inflammation dependent on a combination

  15. Geochemical composition of river loads in the Tropical Andes: first insights from the Ecuadorian Andes

    NASA Astrophysics Data System (ADS)

    Tenorio Poma, Gustavo; Govers, Gerard; Vanacker, Veerle; Bouillon, Steven; Álvarez, Lenín; Zhiminaicela, Santiago

    2015-04-01

    Processes governing the transport of total suspended material (TSM), total dissolved solids (TDS) and particulate organic carbon (POC) are currently not well known for Tropical Andean river systems. We analyzed the geochemical behavior and the budgets of the particulate and dissolved loads for several sub-catchments in the Paute River basin in the southern Ecuadorian Andes, and examined how anthropogenic activities influenced the dynamics of riverine suspended and dissolved loads. We gathered a large dataset by regularly sampling 8 rivers for their TSM, POC, and TDS. Furthermore, we determined the major elements in the dissolved load and stable isotope composition (δ13C) of both the POC, and the dissolved inorganic carbon (DIC). The rivers that were sampled flow through a wide range of land uses including: 3 nature conservation areas (100 - 300 Km²), an intensive grassland and arable zone (142 Km²); downstream of two cities (1611 and 443 Km²), and 2 degraded basins (286 and 2492 Km²). We described the geochemical characteristics of the river loads both qualitatively and quantitatively. Important differences in TSM, POC and TDS yields were found between rivers: the concentration of these loads increases according with human activities within the basins. For all rivers, TSM, TDS and POC concentrations were dependent on discharge. Overall, a clear relation between TSM and POC (r²=0.62) was observed in all tributaries. The C:N ratios and δ13CPOC suggest that the POC in most rivers is mainly derived from soil organic matter eroded from soils dominated by C3 vegetation (δ13CPOC < -22‰). Low Ca:Si ratios (<1)and high δ13CDIC (-9 to -4) in the Yanuncay, Tomebamba1 and Machángara, rivers suggest that weathering of silica rocks is dominant in these catchments, and that the DIC is mainly derived from the soil or atmospheric CO2. In contrast, the Ca:Si ratio was high for the Burgay and Jadán rivers (1-13), and the low δ13CDIC values (-9 to -15) suggest that

  16. Is tourism damaging ecosystems in the Andes? Current knowledge and an agenda for future research.

    PubMed

    Barros, Agustina; Monz, Christopher; Pickering, Catherine

    2015-03-01

    Despite the popularity of tourism and recreation in the Andes in South America and the regions conservation value, there is limited research on the ecological impacts of these types of anthropogenic use. Using a systematic quantitative literature review method, we found 47 recreation ecology studies from the Andes, 25 of which used an experimental design. Most of these were from the Southern Andes in Argentina (13 studies) or Chile (eight studies) with only four studies from the Northern Andes. These studies documented a range of impacts on vegetation, birds and mammals; including changes in plant species richness, composition and vegetation cover and the tolerance of wildlife of visitor use. There was little research on the impacts of visitors on soils and aquatic systems and for some ecoregions in the Andes. We identify research priorities across the region that will enhance management strategies to minimise visitor impacts in Andean ecosystems.

  17. Tectonic implications of tomographic images of subducted lithosphere beneath Northwestern South America

    SciTech Connect

    Van Der Hilst, R. ); Mann, P. )

    1993-02-01

    Tomographic images and deep seismicity of the mantle beneath northwestern South America support the existence of extensive and continuous subducted slabs which may be important controls on the neotectonic deformation of the overriding South America plate. Using tomographic data, we have estimated lateral continuity, regional dip, downdip length and approximate convergence direction of two, largely aseismic slabs. Tomographic data suggests that the Cauca slab, previously defined using earthquakes beneath southern Colombia, extends 300 km into the mantle beneath northern Colombia, has an average dip of 50[degrees], and is the downdip extension of Eocene to Miocene Panama island arc and Oligocene-Miocene oceanic crust of the Nazca plate. The Maracaibo slab of northern Colombia and western Venezuela extends up to 450 km into the mantle at an average angle of 16[degrees] and is the downdip extension of Late Cretaceous oceanic plateau crust of the Caribbean Sea. The boundary between the two slabs is less than 50 km in width. The Maracaibo and northern Cauca slabs are generally aseismic and not associated with an overlying volcanic arc. Instead, both slabs are overlain by broad zones of diffuse active faulting and topography in the northern Andes. The shallow dip, angle of oblique subduction and thickness of the Maracaibo slab may produce crustal deformation including northward tectonic escape of the Maracaibo block, a triangular wedge of continental crust in the overriding South America plate.

  18. Transmission Study of Andes Hantavirus Infection in Wild Sigmodontine Rodents†

    PubMed Central

    Padula, P.; Figueroa, R.; Navarrete, M.; Pizarro, E.; Cadiz, R.; Bellomo, C.; Jofre, C.; Zaror, L.; Rodriguez, E.; Murúa, R.

    2004-01-01

    Our study was designed to contribute to an understanding of the timing and conditions under which transmission of Andes hantavirus in Oligoryzomys longicaudatus reservoir populations takes place. Mice were caged in test habitats consisting of steel drums containing holding cages, where seronegative rodents were exposed to wild seropositive individuals by freely sharing the same cage or being separated by a wire mesh. Tests were also performed for potential viral transmission to mice from excrement-tainted bedding in the cages. Andes virus transmitted efficiently; from 130 attempts with direct contact, 12.3% resulted in virus transmission. However, if we consider only those rodents that proved to be infectious, from 93 attempts we obtained 16 infected animals (17.2%). Twelve of them resulted from intraspecies O. longicaudatus encounters where male mice were differentially affected and 4 resulted from O. longicaudatus to Abrothrix olivaceus. Experiments using Abrothrix longipilis as receptors were not successful. Transmission was not observed between wire mesh-separated animals, and mice were not infected from excrement-tainted bedding. Bites seemed not to be a requisite for oral transmission. Genomic viral RNA was amplified in two out of three saliva samples from seropositive rodents, but it was not detected in urine samples obtained by vesicle puncture from two other infected rodents. Immunohistochemistry, using antibodies against Andes (AND) hantavirus proteins, revealed strong reactions in the lung and salivary glands, supporting the possibility of oral transmission. Our study suggests that AND hantavirus may be principally transmitted via saliva or saliva aerosols rather than via feces and urine. PMID:15479837

  19. Venezuelan equine encephalitis virus entry mechanism requires late endosome formation and resists cell membrane cholesterol depletion

    SciTech Connect

    Kolokoltsov, Andrey A.; Fleming, Elisa H.; Davey, Robert A. . E-mail: radavey@utmb.edu

    2006-04-10

    Virus envelope proteins determine receptor utilization and host range. The choice of receptor not only permits specific targeting of cells that express it, but also directs the virus into specific endosomal trafficking pathways. Disrupting trafficking can result in loss of virus infectivity due to redirection of virions to non-productive pathways. Identification of the pathway or pathways used by a virus is, thus, important in understanding virus pathogenesis mechanisms and for developing new treatment strategies. Most of our understanding of alphavirus entry has focused on the Old World alphaviruses, such as Sindbis and Semliki Forest virus. In comparison, very little is known about the entry route taken by more pathogenic New World alphaviruses. Here, we use a novel contents mixing assay to identify the cellular requirements for entry of a New World alphavirus, Venezuelan equine encephalitis virus (VEEV). Expression of dominant negative forms of key endosomal trafficking genes shows that VEEV must access clathrin-dependent endocytic vesicles for membrane fusion to occur. Unexpectedly, the exit point is different from Old World alphaviruses that leave from early endosomes. Instead, VEEV also requires functional late endosomes. Furthermore, unlike the Old World viruses, VEEV entry is insensitive to cholesterol sequestration from cell membranes and may reflect a need to access an endocytic compartment that lacks cholesterol. This indicates fundamental differences in the entry route taken by VEEV compared to Old World alphaviruses.

  20. Complete inactivation of Venezuelan equine encephalitis virus by 1,5-iodonaphthylazide

    SciTech Connect

    Sharma, Anuj; Raviv, Yossef; Puri, Anu; Viard, Mathias; Blumenthal, Robert; Maheshwari, Radha K. . E-mail: rmaheshwari@usuhs.mil

    2007-06-29

    Hydrophobic alkylating compounds like 1,5-iodonaphthylazide (INA) partitions into biological membranes and accumulates selectively into the hydrophobic domain of the lipid bilayer. Upon irradiation with far UV light, INA binds selectively to transmembrane proteins in the viral envelope and renders them inactive. Such inactivation does not alter the ectodomains of the membrane proteins thus preserving the structural and conformational integrity of immunogens on the surface of the virus. In this study, we have used INA to inactivate Venezuelan equine encephalitis virus (VEEV). Treatment of VEEV with INA followed by irradiation with UV light resulted in complete inactivation of the virus. Immuno-fluorescence for VEEV and virus titration showed no virus replication in-vitro. Complete loss of infectivity was also achieved in mice infected with INA treated plus irradiated preparations of VEEV. No change in the structural integrity of VEEV particles were observed after treatment with INA plus irradiation as assessed by electron microscopy. This data suggest that such inactivation strategies can be used for developing vaccine candidates for VEEV and other enveloped viruses.

  1. [Microbiological assessment of the Gouda-type cheese-making process in a Venezuelan industry].

    PubMed

    Dáivila, Jacqueline; Reyes, Genara; Corzo, Otoniel

    2006-03-01

    The adoption of the Hazard Analysis and Critical Control Point (HACCP) system is necessary to assure the safety of the product in the cheese-making industry. The compliment of pre-requisite programs as Good Manufacture Practices (GMPs) and Sanitation Standard Operating Procedures (SSOPs) are required before the implementation of the HACCP plan. GMPs are the standards related to equipments, tools, personnel, etc. SSOPs are the procedures related to hygiene and sanitation of the plant and workers. The aim of this study was to assess the compliment of the pre-requisite programs and the microbiological conditions of the Gouda type cheese-making process in a Venezuelan processing plant before designing a HACCP plan. Samples were: (a) raw milk, pasteurized milk, curd and ripened cheese, (b) water, (c) environment of the production areas and ripening premises, (d) equipments before and after sanitation, (e) food handlers. Microbiological analyses were done according to COVENIN standards. This study showed that even though pasteurization process was effective to kill pathogen bacteria of the raw milk and the water was safe, however there are deficient manufacture practices in the hygiene as well as in sanitation of the plant and food handlers. Prerequisite programs (GMP-SSOP) of this industry need to be well established, controlled and evaluated. PMID:16786734

  2. Relative frequencies of rotavirus serotypes 1, 2, 3, and 4 in Venezuelan infants with gastroenteritis.

    PubMed Central

    Flores, J; Taniguchi, K; Green, K; Perez-Schael, I; Garcia, D; Sears, J; Urasawa, S; Kapikian, A Z

    1988-01-01

    We have used a recently developed monoclonal antibody enzyme-linked immunosorbent assay (K. Taniguchi, T. Urasawa, Y. Morita, H. B. Greenberg, and S. Urasawa, J. Infect. Dis. 155:1159-1166, 1987) for serotyping rotaviruses recovered from 134 Venezuelan infants over a period of 15 months. One hundred and nine of the specimens were typed with the following distribution: serotype 1, 48%; serotype 2, 16%; serotype 3, 22%; and serotype 4, 14%. Three specimens reacted with two different monoclonal antibodies. In addition, 6 specimens (5%) containing enough outer capsid antigen could not be typed; partial RNA sequence analysis of the glycoprotein gene from three of these six strains failed to reveal sequence differences with prototype strains that could be serotyped with the monoclonal antibodies. Variations in the recovery rates of the different serotypes were observed. Serotypes 2, 3, and 4 predominated at the beginning of the study, and serotype 1 predominated at the end of the study. Diarrheal illness appeared to be more prolonged in infants shedding rotavirus serotypes 1 and 3 than in those shedding serotypes 2 and 4. PMID:2846637

  3. Biosurfactant production by marine bacterial isolates from the Venezuelan Atlantic Front.

    PubMed

    Bozo-Hurtado, Lorelei; Rocha, Carlos A; Malavé, Raydav; Suárez, Paula

    2012-11-01

    Our purpose was to detect, isolate and characterize tensioactive agents with or without emulsifying activity from marine bacterial strains present in seawater and sediment samples from the Venezuelan Atlantic Front. Biosurfactants found in cell-free supernatants from all cultures presented high surface activity as they were able to reduce the water surface tension from 72 dynes cm(-1) to values between 41.7 and 33.9 dynes cm(-1). However, high indirect CMC values were registered for the most of these compounds (51.4%-56.1% v/v). Culture supernatants from S3 and S29 strains showed highest emulsifying activity in the dispersion assay with diesel oil (absorbance 1.06 and 1.18, respectively), while supernatant from the S10 strain induced the most stable oil-in-water emulsions with 16° and 25°API crude oils. Only culture supernatant from S3 strain was able to produce stable oil-in water emulsions with diesel oil and both type of crude oils.

  4. Genetic and Anatomic Determinants of Enzootic Venezuelan Equine Encephalitis Virus Infection of Culex (Melanoconion) taeniopus

    PubMed Central

    Kenney, Joan L.; Adams, A. Paige; Gorchakov, Rodion; Leal, Grace; Weaver, Scott C.

    2012-01-01

    Venezuelan equine encephalitis (VEE) is a re-emerging, mosquito-borne viral disease with the potential to cause fatal encephalitis in both humans and equids. Recently, detection of endemic VEE caused by enzootic strains has escalated in Mexico, Peru, Bolivia, Colombia and Ecuador, emphasizing the importance of understanding the enzootic transmission cycle of the etiologic agent, VEE virus (VEEV). The majority of work examining the viral determinants of vector infection has been performed in the epizootic mosquito vector, Aedes (Ochlerotatus) taeniorhynchus. Based on the fundamental differences between the epizootic and enzootic cycles, we hypothesized that the virus-vector interaction of the enzootic cycle is fundamentally different from that of the epizootic model. We therefore examined the determinants for VEEV IE infection in the enzootic vector, Culex (Melanoconion) taeniopus, and determined the number and susceptibility of midgut epithelial cells initially infected and their distribution compared to the epizootic virus-vector interaction. Using chimeric viruses, we demonstrated that the determinants of infection for the enzootic vector are different than those observed for the epizootic vector. Similarly, we showed that, unlike A. taeniorhynchus infection with subtype IC VEEV, C. taeniopus does not have a limited subpopulation of midgut cells susceptible to subtype IE VEEV. These findings support the hypothesis that the enzootic VEEV relationship with C. taeniopus differs from the epizootic virus-vector interaction in that the determinants appear to be found in both the nonstructural and structural regions, and initial midgut infection is not limited to a small population of susceptible cells. PMID:22509419

  5. Complete inactivation of Venezuelan equine encephalitis virus by 1,5-iodonaphthylazide.

    PubMed

    Sharma, Anuj; Raviv, Yossef; Puri, Anu; Viard, Mathias; Blumenthal, Robert; Maheshwari, Radha K

    2007-06-29

    Hydrophobic alkylating compounds like 1,5-iodonaphthylazide (INA) partitions into biological membranes and accumulates selectively into the hydrophobic domain of the lipid bilayer. Upon irradiation with far UV light, INA binds selectively to transmembrane proteins in the viral envelope and renders them inactive. Such inactivation does not alter the ectodomains of the membrane proteins thus preserving the structural and conformational integrity of immunogens on the surface of the virus. In this study, we have used INA to inactivate Venezuelan equine encephalitis virus (VEEV). Treatment of VEEV with INA followed by irradiation with UV light resulted in complete inactivation of the virus. Immuno-fluorescence for VEEV and virus titration showed no virus replication in-vitro. Complete loss of infectivity was also achieved in mice infected with INA treated plus irradiated preparations of VEEV. No change in the structural integrity of VEEV particles were observed after treatment with INA plus irradiation as assessed by electron microscopy. This data suggest that such inactivation strategies can be used for developing vaccine candidates for VEEV and other enveloped viruses.

  6. [Historic record of Gastrotheca ovifera (Anura: Hemiphractidae): decline evidence in Venezuelan coastal cloud forests].

    PubMed

    Valera-Leal, Javier; Acevedo, Aldemar; Pérez-Sánchez, Antonio; Vega, Jorge; Manzanilla, Jesús

    2011-03-01

    G. ovifera is a marsupial frog of the cloud and riparian forest from Western and Litoral sections of the Venezuelan Cordillera de la Costa (820-2 000m). This amphibian is considered as an endangered species by the IUCN Species Red List, due to its population decline in pristine and well preserved environments. This conservation status is based on anecdotic interpretations. We collected disperse data from museum records (national and international) and explored the possible association between collection records and precipitation data available for the Henri Pittier National Park (PNHP). Likewise, we carried out a systematic population monitoring of G. ovifera in historic and additional localities among the cloud forest of Rancho Grande, PNHP. We found 106 individuals in 11 zoological collections deposited during 1929-2007. After an effort of 646 hours/person we did not detect G. ovifera individuals in the evaluated localities; as well as no statistical significant associations between the annual precipitation average and the historic records of the species during 1941-1997 period (r = -0.054, p = 0.820, n = 19). We discussed the distribution, fluctuation and population changes of this species, analyzing it conservation status. PMID:21516654

  7. An optical luminescence chronology for late Pleistocene aeolian activity in the Colombian and Venezuelan Llanos

    NASA Astrophysics Data System (ADS)

    Carr, Andrew S.; Armitage, Simon J.; Berrío, Juan-Carlos; Bilbao, Bibiana A.; Boom, Arnoud

    2016-03-01

    The lowland savannas (Llanos) of Colombia and Venezuela are covered by extensive aeolian landforms for which little chronological information exists. We present the first optically stimulated luminescence (OSL) age constraints for dunes in the Llanos Orientales of lowland Colombia and new ages for dunes in the Venezuelan Llanos. The sampled dunes are fully vegetated and show evidence of post-depositional erosion. Ages range from 4.5 ± 0.4 to 66 ± 4 ka, with the majority dating to 27-10 ka (Marine Isotope Stage 2). Some dunes accumulated quickly during the last glacial maximum, although most were active 16-10 ka. Accretion largely ceased after 10 ka. All dunes are elongated downwind from rivers, parallel with dry season winds, and are interpreted as source-bordering features. As they are presently isolated from fluvial sediments by gallery forest it is proposed that activity was associated with a more prolonged dry season, which restricted gallery forest, leading to greater sediment availability on river shorelines. Such variability in dry season duration was potentially mediated by the mean latitude of the ITCZ. The cessation of most dune accretion after ca. 10 ka suggests reduced seasonality and a more northerly ITCZ position, consistent with evidence from the Cariaco Basin.

  8. [Microbiological assessment of the Gouda-type cheese-making process in a Venezuelan industry].

    PubMed

    Dáivila, Jacqueline; Reyes, Genara; Corzo, Otoniel

    2006-03-01

    The adoption of the Hazard Analysis and Critical Control Point (HACCP) system is necessary to assure the safety of the product in the cheese-making industry. The compliment of pre-requisite programs as Good Manufacture Practices (GMPs) and Sanitation Standard Operating Procedures (SSOPs) are required before the implementation of the HACCP plan. GMPs are the standards related to equipments, tools, personnel, etc. SSOPs are the procedures related to hygiene and sanitation of the plant and workers. The aim of this study was to assess the compliment of the pre-requisite programs and the microbiological conditions of the Gouda type cheese-making process in a Venezuelan processing plant before designing a HACCP plan. Samples were: (a) raw milk, pasteurized milk, curd and ripened cheese, (b) water, (c) environment of the production areas and ripening premises, (d) equipments before and after sanitation, (e) food handlers. Microbiological analyses were done according to COVENIN standards. This study showed that even though pasteurization process was effective to kill pathogen bacteria of the raw milk and the water was safe, however there are deficient manufacture practices in the hygiene as well as in sanitation of the plant and food handlers. Prerequisite programs (GMP-SSOP) of this industry need to be well established, controlled and evaluated.

  9. Structure of a Venezuelan equine encephalitis virus assembly intermediate isolated from infected cells

    SciTech Connect

    Lamb, Kristen; Lokesh, G.L.; Sherman, Michael; Watowich, Stanley

    2010-10-25

    Venezuelan equine encephalitis virus (VEEV) is a prototypical enveloped ssRNA virus of the family Togaviridae. To better understand alphavirus assembly, we analyzed newly formed nucleocapsid particles (termed pre-viral nucleocapsids) isolated from infected cells. These particles were intermediates along the virus assembly pathway, and ultimately bind membrane-associated viral glycoproteins to bud as mature infectious virus. Purified pre-viral nucleocapsids were spherical with a unimodal diameter distribution. The structure of one class of pre-viral nucleocapsids was determined with single particle reconstruction of cryo-electron microscopy images. These studies showed that pre-viral nucleocapsids assembled into an icosahedral structure with a capsid stoichiometry similar to the mature nucleocapsid. However, the individual capsomers were organized significantly differently within the pre-viral and mature nucleocapsids. The pre-viral nucleocapsid structure implies that nucleocapsids are highly plastic and undergo glycoprotein and/or lipid-driven rearrangements during virus self-assembly. This mechanism of self-assembly may be general for other enveloped viruses.

  10. Role of Dendritic Cell Targeting in Venezuelan Equine Encephalitis Virus Pathogenesis

    PubMed Central

    MacDonald, Gene H.; Johnston, Robert E.

    2000-01-01

    The initial steps of Venezuelan equine encephalitis virus (VEE) spread from inoculation in the skin to the draining lymph node have been characterized. By using green fluorescent protein and immunocytochemistry, dendritic cells in the draining lymph node were determined to be the primary target of VEE infection in the first 48 h following inoculation. VEE viral replicon particles, which can undergo only one round of infection, identified Langerhans cells to be the initial set of cells infected by VEE directly following inoculation. These cells are resident dendritic cells in the skin, which migrate to the draining lymph node following activation. A point mutation in the E2 glycoprotein gene of VEE that renders the virus avirulent and compromises its ability to spread beyond the draining lymph blocked the appearance of virally infected dendritic cells in the lymph node in vivo. A second-site suppressor mutation that restores viral spread to lymphoid tissues and partially restore virulence likewise restored the ability of VEE to infect dendritic cells in vivo. PMID:10623754

  11. Clinical trial with Secnidazole in a single dose in Venezuelan children infected by Giardia intestinalis.

    PubMed

    Di Prisco, M C; Jiménez, J C; Rodríguez, N; Costa, V; Villamizar, J; Silvera, A; Carrillo, M; Lira, C; Zerpa, E; López, Y

    2000-09-01

    The aim of this work was to evaluate in an open, noncomparative study the use of secnidazole in oral suspension given to Venezuelan children infected with Giardia intestinalis, from a community in Carapita, a slum area in Caracas. Seventy children from 2 to 11 years old (38 males and 32 females) were treated with a single oral dose of secnidazole (30 mg/Kg of body weight), after clinical and parasitological evaluation to make the diagnosis of active giardiasis. The effectiveness of treatment was determined by clinical examination and parasitological evaluation of feces samples 15 days after treatment. The results showed 95% of clinical cure with a significant decrease of the frequency of gastrointestinal symptoms. The parasitological cure was 98%, there were 4 failures at the end of treatment. Side effects observed after treatment were of mild intensity, lasting only few hours. These results show that a simple dose of secnidazole in an oral suspension is an effective, safe and well tolerated treatment for giardiasis in children and that this drug may be used as a mass treatment in risk populations. PMID:11029834

  12. Iron bioavailability from diets consumed by different socioeconomic strata of the Venezuelan population.

    PubMed

    Taylor, P G; Méndez-Castellanos, H; Martínez-Torres, C; Jaffe, W; López de Blanco, M; Landaeta-Jiménez, M; Leets, I; Tropper, E; Ramírez, J; García Casal, M N

    1995-07-01

    The iron bioavailability from three typical diets consumed by socioeconomic stratum IV (SES IV--working class) of the Venezuelan population was determined by the extrinsic label method. Although the iron content of the SES IV diets was about the same (250 mumol/d) as that of upper (SES I-III) and lower (SES V) socioeconomic strata diets, iron-replete subjects absorbed 43 and 61% more iron from the SES I-III diets than from the SES IV and V diets, respectively, and absorption from the main meal of the SES I-III diets was 100% greater. However, iron deficient subjects absorbed about the same amount of iron (45 mumol/d) from the SES IV diets as from the SES I-III diets. The SES I-III diets contained more iron absorption enhancers (ascorbic acid and meat protein) and less of the inhibitor phytate, than the SES IV and V diets. Iron absorption from the meals of four diets consumed at different times during the day was also measured. There was no significant difference in the percentage iron absorption from the same meals eaten in the morning after an overnight fast, and when eaten at the customary time of day.

  13. Venezuelan Equine Encephalitis Virus in Iquitos, Peru: Urban Transmission of a Sylvatic Strain

    PubMed Central

    Morrison, Amy C.; Forshey, Brett M.; Notyce, Desiree; Astete, Helvio; Lopez, Victor; Rocha, Claudio; Carrion, Rebecca; Carey, Cristhiam; Eza, Dominique; Montgomery, Joel M.; Kochel, Tadeusz J.

    2008-01-01

    Enzootic strains of Venezuelan equine encephalitis virus (VEEV) have been isolated from febrile patients in the Peruvian Amazon Basin at low but consistent levels since the early 1990s. Through a clinic-based febrile surveillance program, we detected an outbreak of VEEV infections in Iquitos, Peru, in the first half of 2006. The majority of these patients resided within urban areas of Iquitos, with no report of recent travel outside the city. To characterize the risk factors for VEEV infection within the city, an antibody prevalence study was carried out in a geographically stratified sample of urban areas of Iquitos. Additionally, entomological surveys were conducted to determine if previously incriminated vectors of enzootic VEEV were present within the city. We found that greater than 23% of Iquitos residents carried neutralizing antibodies against VEEV, with significant associations between increased antibody prevalence and age, occupation, mosquito net use, and overnight travel. Furthermore, potential vector mosquitoes were widely distributed across the city. Our results suggest that while VEEV infection is more common in rural areas, transmission also occurs within urban areas of Iquitos, and that further studies are warranted to identify the precise vectors and reservoirs involved in urban VEEV transmission. PMID:19079600

  14. Early local last glacial maximum in the tropical Andes.

    PubMed

    Smith, Jacqueline A; Seltzer, Geoffrey O; Farber, Daniel L; Rodbell, Donald T; Finkel, Robert C

    2005-04-29

    The local last glacial maximum in the tropical Andes was earlier and less extensive than previously thought, based on 106 cosmogenic ages (from beryllium-10 dating) from moraines in Peru and Bolivia. Glaciers reached their greatest extent in the last glacial cycle approximately 34,000 years before the present and were retreating by approximately 21,000 years before the present, implying that tropical controls on ice volumes were asynchronous with those in the Northern Hemisphere. Our estimates of snowline depression reflect about half the temperature change indicated by previous widely cited figures, which helps resolve the discrepancy between estimates of terrestrial and marine temperature depression during the last glacial cycle.

  15. Altiplano-Puna volcanic complex of the central Andes

    NASA Technical Reports Server (NTRS)

    De Silva, S. L.

    1989-01-01

    A model is presented accounting for many features of the Altiplano-Puna volcanic complex situated in the Central Volcanic Zone of the Andes which contains 50 recently active volcanoes. The dominant elements of the complex are several large nested caldera complexes which are the source structures for the major regionally distributed ignimbrite sheets that characterize the complex. The study of the complex reveals the importance of the intersection of subsidiary axis-oblique tectonic trends related to regional stress fields peculiar to individual oceanic ridge sections with the axis-parallel trends predominant at all spreading centers in localizing hydrothermal discharge zones.

  16. Flood of September 2008 in Northwestern Indiana

    USGS Publications Warehouse

    Fowler, Kathleen K.; Kim, Moon H.; Menke, Chad D.; Arvin, Donald V.

    2010-01-01

    During September 12-15, 2008, rainfall ranging from 2 to more than 11 inches fell on northwestern Indiana. The rainfall resulted in extensive flooding on many streams within the Lake Michigan and Kankakee River Basins during September 12-18, causing two deaths, evacuation of hundreds of residents, and millions of dollars of damage to residences, businesses, and infrastructure. In all, six counties in northwestern Indiana were declared Federal disaster areas. U.S. Geological Survey (USGS) streamgages at four locations recorded new record peak streamflows as a result of the heavy rainfall. Peak-gage-height data, peak-streamflow data, annual exceedance probabilities, and recurrence intervals are tabulated in this report for 10 USGS streamgages in northwestern Indiana. Recurrence intervals of flood-peak streamflows were estimated to be greater than 100 years at six streamgages. Because flooding was particularly severe in the communities of Munster, Dyer, Hammond, Highland, Gary, Lake Station, Hobart, Schererville, Merrillville, Michiana Shores, and Portage, high-water-park data collected after the flood were tabulated for those communities. Flood peak inundation maps and water-surface profiles for selected streams were made in a geographic information system by combining high-water-mark data with the highest resolution digital elevation model data available.

  17. Episodic Cenozoic volcanism and tectonism in the Andes of Peru

    USGS Publications Warehouse

    Noble, D.C.; McKee, E.H.; Farrar, E.; Petersen, U.

    1974-01-01

    Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise. ?? 1974.

  18. Diffusion and spatially resolved NMR in Berea and Venezuelan oil reservoir rocks.

    PubMed

    Murgich, J; Corti, M; Pavesi, L; Voltini, F

    1992-01-01

    Conventional and spatially resolved proton NMR and relaxation measurements are used in order to study the molecular motions and the equilibrium and nonequilibrium diffusion of oils in Berea sandstone and Venezuelan reservoir rocks. In the water-saturated Berea a single line with T*2 congruent to 150 microseconds is observed, while the relaxation recovery is multiexponential. In an oil reservoir rock (Ful 13) a single narrow line is present while a distribution of relaxation rates is evidenced from the recovery plots. On the contrary, in the Ful 7 sample (extracted at a deeper depth in a different zone) two NMR components are present, with 3.5 and 30 KHz linewidths, and the recovery plot exhibits biexponential law. No echo signal could be reconstructed in the oil reservoir rocks. These findings can be related to the effects in the micropores, where motions at very low frequency can occur in a thin layer. From a comparison of the diffusion constant in water-saturated Berea, D congruent to 5*10(-6) cm2/sec, with the ones in model systems, the average size of the pores is estimated around 40 A. The density profiles at the equilibrium show uniform distribution of oils or of water, and the relaxation rates appear independent from the selected slice. The nonequilibrium diffusion was studied as a function of time in a Berea cylinder with z axis along H0, starting from a thin layer of oil at the base, and detecting the spin density profiles d(z,t) with slice-selection techniques. Simultaneously, the values of T1's were measured locally, and the distribution of the relaxation rates was observed to be present in any slice.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. The Ubiquitin Proteasome System Plays a Role in Venezuelan Equine Encephalitis Virus Infection

    PubMed Central

    Amaya, Moushimi; Keck, Forrest; Lindquist, Michael; Voss, Kelsey; Scavone, Lauren; Kehn-Hall, Kylene; Roberts, Brian; Bailey, Charles; Schmaljohn, Connie; Narayanan, Aarthi

    2015-01-01

    Many viruses have been implicated in utilizing or modulating the Ubiquitin Proteasome System (UPS) to enhance viral multiplication and/or to sustain a persistent infection. The mosquito-borne Venezuelan equine encephalitis virus (VEEV) belongs to the Togaviridae family and is an important biodefense pathogen and select agent. There are currently no approved vaccines or therapies for VEEV infections; therefore, it is imperative to identify novel targets for therapeutic development. We hypothesized that a functional UPS is required for efficient VEEV multiplication. We have shown that at non-toxic concentrations Bortezomib, a FDA-approved inhibitor of the proteasome, proved to be a potent inhibitor of VEEV multiplication in the human astrocytoma cell line U87MG. Bortezomib inhibited the virulent Trinidad donkey (TrD) strain and the attenuated TC-83 strain of VEEV. Additional studies with virulent strains of Eastern equine encephalitis virus (EEEV) and Western equine encephalitis virus (WEEV) demonstrated that Bortezomib is a broad spectrum inhibitor of the New World alphaviruses. Time-of-addition assays showed that Bortezomib was an effective inhibitor of viral multiplication even when the drug was introduced many hours post exposure to the virus. Mass spectrometry analyses indicated that the VEEV capsid protein is ubiquitinated in infected cells, which was validated by confocal microscopy and immunoprecipitation assays. Subsequent studies revealed that capsid is ubiquitinated on K48 during early stages of infection which was affected by Bortezomib treatment. This study will aid future investigations in identifying host proteins as potential broad spectrum therapeutic targets for treating alphavirus infections. PMID:25927990

  20. Genetic and evolutionary characterization of Venezuelan equine encephalitis virus isolates from Argentina.

    PubMed

    Pisano, María Belén; Torres, Carolina; Ré, Viviana Elizabeth; Farías, Adrián Alejandro; Sánchez Seco, María Paz; Tenorio, Antonio; Campos, Rodolfo; Contigiani, Marta Silvia

    2014-08-01

    Venezuelan equine encephalitis viruses (VEEV) are emerging pathogens of medical and veterinary importance circulating in America. Argentina is a country free from epizootic VEEV activity, with circulation of enzootic strains belonging to Rio Negro virus (RNV; VEEV subtype VI) and Pixuna virus (PIXV, VEEV subtype IV). In this work, we aim to report the sequencing and phylogenetic analyses of all Argentinean VEE viruses, including 7 strains previously isolated from mosquitoes in 1980, 5 sequences obtained from rodents in 1991 and 11 sequences amplified from mosquitoes between 2003 and 2005. Two genomic regions, corresponding to the non-structural protein 4 (nsP4) and the protein E3/E2 (PE2) genes were analyzed, but only 8 samples could be amplified in the last one (longer and more variable fragment of 702 bp). For both genomic fragments, phylogenetic trees showed the absence of lineages within RNV group, and a close genetic relationship between Argentinean strains and the prototype strain BeAr35645 for PIXV clade. The analysis of nsP4 gene opens the possibility to propose a possible geographic clustering of strains within PIXV group (Argentina and Brazil). Coalescent analysis performed on RNV sequences suggested a common ancestor of 58.3 years (with a 95% highest posterior density [HPD] interval of 16.4-345.7) prior to 1991 and inferred a substitution rate of 9.8×10(-5)substitutions/site/year, slightly lower than other enzootic VEE viruses. These results provide, for the first time, information about genetic features and variability of all VEEVs detected in Argentina, creating a database that will be useful for future detections in our country. This is particularly important for RNV, which has indigenous circulation. PMID:24833218

  1. [Presence of antibodies against Venezuelan equine encephalitis virus subtype VI in patients with acute febrile illness].

    PubMed

    Contigiani, M S; de Basualdo, M; Cámara, A; Ramírez, A; Díaz, G; González, D; Medeot, S; Osuna, D

    1993-01-01

    In Argentina, there is no record of human cases produced by Dengue virus (Flavivirus), but Paraguay and Brasil (neighbouring countries) have notified human outbreaks of Dengue Haemorrhagic Fever. In this report, we inform the serological results of a limited human outbreak of a Dengue-like acute illness that occurred in General Belgrano Island, Formosa, Argentina in April 1989. This island is 35 km far from Clorinda city of Paraguay river, with a human population of 150 inhabitants. The weather of this area is humid with abundant rainfall, favouring mosquitoes proliferation. Two samples of serum from 28 human notified cases were studied using hemagglutination inhibition test (HI), complement fixation (CF), and plaque reduction neutralization (NT) test in Vero cell cultures. All tested sera were negative to Dengue, St. Louis encephalitis, Yellow Fever, Bussuquara, Rocio, Eastern and Western Equine Encephalitis arboviruses as well as Influenza and Rubella viruses. By contrast, infection with Venezuelan equine encephalitis virus (VEE), subtype VI-AG80-663 strain was demonstrated (34.5% positive by HI, 39.1% by CF and 51.6% by NT). Seroconversion was detected by NT in six cases and only five were positive by CF. The 26.8% of the sera reacted also with VEE subtype I AB by NT. Considering that no cross reaction were detected in NT with these two subtypes, our results suggest that both viruses are concomitantly circulating in the studied area. Furthermore, the seroconversions detected with AG80-663 strain firmly indicate that during the outbreak this virus subtype was circulating in the island, although we could not assure that it was the causal agent of the acute disease.

  2. Did growth of high Andes slow down Nazca plate subduction?

    NASA Astrophysics Data System (ADS)

    Quinteros, J.; Sobolev, S. V.

    2010-12-01

    The convergence velocity rate of the Nazca and South-American plate and its variations during the last 100 My are quite well-known from the global plate reconstructions. The key observation is that the rate of Nazca plate subduction has decreased by about 2 times during last 20 Myr and particularly since 10 Ma. During the same time the Central Andes have grown to its present 3-4 km height. Based on the thin-shell model, coupled with mantle convection, it was suggested that slowing down of Nazca plate resulted from the additional load exerted by the Andes. However, the thin-shell model, that integrates stresses and velocities vertically and therefore has no vertical resolution, is not an optimal tool to model a subduction zone. More appropriate would be modeling it with full thermomechanical formulation and self-consistent subduction. We performed a set of experiments to estimate the influence that an orogen like the Andes could have on an ongoing subduction. We used an enhanced 2D version of the SLIM-3D code suitable to simulate the evolution of a subducting slab in a self-consistent manner (gravity driven) at vertical crossections through upper mantle, transition zone and shallower lower mantle. The model utilizes non-linear temperature- and stress-dependant visco-elasto-plastic rheology and phase transitions at 410 and 660 km depth. We started from a reference case with a similar configuration as both Nazca and South-America plates. After some Mys of slow kinematicaly imposed subduction, to develop a coherent thermo-mechanical state, subduction was totally dynamic. On the other cases, the crust was slowly thickened artificially during 10 My to generate the Andean topography. Although our first results show no substantial changes on the velocity pattern of the subduction, we, however, consider this result as preliminary. At the meeting we plan to report completed and verified modeling results and discuss other possible cases of the late Cenozoic slowing down of

  3. Prediction equations for Warner-Bratzler shear force using principal component regression analysis in Brahman-influenced Venezuelan cattle.

    PubMed

    Jerez-Timaure, N; Huerta-Leidenz, N; Ortega, J; Rodas-González, A

    2013-03-01

    A database consisting of 331 beef animals (Brahman-crossbred) was used to determine the multivariate relationships between carcass and beef palatability traits of Venezuelan cattle and to develop prediction equations for Warner-Bratzler shear force (WBSF). The first three principal components (PC) explained 77.53% of the standardized variance. Equations were obtained for each sex class and the total variability observed in WBSF could be explained by its orthogonal regression with carcass weight (CW), fat cover (FC), fat thickness (FT), and skeletal maturity (SM). Prediction equations were: WBSF(steers)=3.566+0.003(CW)-0.033(FC)-0.015(FT)+0.0004(SM); WBSF(heifers)=4.824+0.002(CW)-0.229(FC)+0.096(FT)-0.064(SM); WBSF(bulls)=3.516+0.009(CW)+0.154(FC)-0.129(FT)-0.006(SM). A higher proportion of the variation was explained by the PC when variables of greater weight were selected to define each PC. The equation set presented herein could become an important tool to improve the Venezuelan carcass grading system. PMID:23261538

  4. Anaerobic thermophilic bacteria isolated from a Venezuelan oil field and its potential use in microbial improved oil recovery

    SciTech Connect

    Trebbau, G.; Fernandez, B.; Marin, A.

    1995-12-31

    The objective of this work is to determine the ability of indigenous bacteria from a Venezuelan oil field to grow under reservoir conditions inside a porous media, and to produce metabolites capable of recovering residual crude oil. For this purpose, samples of formation waters from a central-eastern Venezuelan oil reservoir were enriched with different carbon sources and a mineral basal media. Formation water was used as a source of trace metals. The enrichments obtained were incubated at reservoir temperature (71{degrees}C), reservoir pressure (1,200 psi), and under anaerobic conditions for both outside and inside porous media (Berea core). Growth and metabolic activity was followed outside porous media by measuring absorbance at 660 nm, increases in pressure, and decreases in pH. Inside porous media bacterial activity was determined by visual examination of the produced waters (gas bubbles and bacterial cells). All the carbohydrates tested outside porous media showed good growth at reservoir conditions. The pH was lowered, gases such as CO{sub 2} and CH{sub 4} were identified by GC. Surface tension was lowered in some enrichments by 30% when compared to controls. Growth was decreased inside porous media, but gases were produced and helped displace oil. In addition, 10% residual oil was recovered from the Berea core. Mathematical modeling was applied to the laboratory coreflood experiment to evaluate the reproducibility of the results obtained.

  5. Prediction equations for Warner-Bratzler shear force using principal component regression analysis in Brahman-influenced Venezuelan cattle.

    PubMed

    Jerez-Timaure, N; Huerta-Leidenz, N; Ortega, J; Rodas-González, A

    2013-03-01

    A database consisting of 331 beef animals (Brahman-crossbred) was used to determine the multivariate relationships between carcass and beef palatability traits of Venezuelan cattle and to develop prediction equations for Warner-Bratzler shear force (WBSF). The first three principal components (PC) explained 77.53% of the standardized variance. Equations were obtained for each sex class and the total variability observed in WBSF could be explained by its orthogonal regression with carcass weight (CW), fat cover (FC), fat thickness (FT), and skeletal maturity (SM). Prediction equations were: WBSF(steers)=3.566+0.003(CW)-0.033(FC)-0.015(FT)+0.0004(SM); WBSF(heifers)=4.824+0.002(CW)-0.229(FC)+0.096(FT)-0.064(SM); WBSF(bulls)=3.516+0.009(CW)+0.154(FC)-0.129(FT)-0.006(SM). A higher proportion of the variation was explained by the PC when variables of greater weight were selected to define each PC. The equation set presented herein could become an important tool to improve the Venezuelan carcass grading system.

  6. Geology and petroleum resources of northwestern Africa

    SciTech Connect

    Peterson, J.A.; Klemme, H.D.

    1986-05-01

    The main onshore basins of northwestern Africa are (1) basins in the Atlas folded geosynclinal belt adjacent to the Mediterranean Sea, (2) the Tindouf, Bechar, and Reggane basins of western Algeria and southern Morocco, and (3) the Taoudeni basin of Mauritania and Mali. Coastal basins are (1) the Essaouria basin of southwestern Morocco, (2) the Tarfaya basin of Western Sahara, (3) the Senegal basin of Senegal and western Mauritania, (4) the Sierra Leone-Liberia basin, and (5) the Ivory Coast basin. The petroleum geology and resource potential of these basins is detailed.

  7. Uranium in saline lakes of Northwestern Mongolia

    NASA Astrophysics Data System (ADS)

    Isupov, V. P.; Vladimirov, A. G.; Lyakhov, N. Z.; Shvartsev, S. L.; Ariunbileg, S.; Kolpakova, M. N.; Shatskaya, S. S.; Chupakhina, L. E.; Kuibida, L. V.; Moroz, E. N.

    2011-03-01

    Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in Lake Hyargas Nuur (about 6000 ton).

  8. Epidemiological modeling and risk analysis of Venezuelan Equine Encephalitis in the human population of Coastal Chiapas, Mexico in 2007-2009

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analysis of 101 febrile illness patients sero positive for Venezuelan equine encephalitis (VEEV) was carried out in a retrospective study along 18 municipalities and endemic VEEV pacific coastal regions of the State of Chiapas in southern Mexico. Geographic information systems (GIS), satellite imag...

  9. Person-to-Person Transmission of Andes Virus

    PubMed Central

    Bellomo, Carla; San Juan, Jorge; Pinna, Diego; Forlenza, Raul; Elder, Malco; Padula, Paula J.

    2005-01-01

    Despite the fact that rodents are considered to be the infectious source of hantavirus for humans, another route of transmission was demonstrated. Andes virus (ANDV) has been responsible for most of the cases recorded in Argentina. Person-to-person transmission of ANDV Sout lineage was described during an outbreak of hantavirus pulmonary syndrome in southwest Argentina. In this study, we analyzed 4 clusters that occurred in 2 disease-endemic areas for different ANDV lineages. We found new evidence of interhuman transmission for ANDV Sout lineage and described the first event in which another lineage, ANDV Cent BsAs, was implicated in this mechanism of transmission. On the basis of epidemiologic and genetic data, we concluded that person-to-person spread of the virus likely took place during the prodromal phase or shortly after it ended, since close and prolonged contact occurred in the events analyzed here, and the incubation period was 15–24 days. PMID:16485469

  10. Early local last glacial maximum in the tropical Andes.

    PubMed

    Smith, Jacqueline A; Seltzer, Geoffrey O; Farber, Daniel L; Rodbell, Donald T; Finkel, Robert C

    2005-04-29

    The local last glacial maximum in the tropical Andes was earlier and less extensive than previously thought, based on 106 cosmogenic ages (from beryllium-10 dating) from moraines in Peru and Bolivia. Glaciers reached their greatest extent in the last glacial cycle approximately 34,000 years before the present and were retreating by approximately 21,000 years before the present, implying that tropical controls on ice volumes were asynchronous with those in the Northern Hemisphere. Our estimates of snowline depression reflect about half the temperature change indicated by previous widely cited figures, which helps resolve the discrepancy between estimates of terrestrial and marine temperature depression during the last glacial cycle. PMID:15860623

  11. Ancient ice islands in salt lakes of the Central Andes

    USGS Publications Warehouse

    Hurlbert, S.H.; Chang, Cecily C.Y.

    1984-01-01

    Massive blocks of freshwater ice and frozen sediments protrude from shallow, saline lakes in the Andes of southwestern Bolivia and northeastern Chile. These ice islands range up to 1.5 kilometers long, stand up to 7 meters above the water surface, and may extend out tens of meters and more beneath the unfrozen lake sediments. The upper surfaces of the islands are covered with dry white sediments, mostly aragonite or calcite. The ice blocks may have formed by freezing of the fresh pore water of lake sediments during the "little ice age." The largest blocks are melting rapidly because of possibly recent increases in geothermal heat flux through the lake bottom and undercutting by warm saline lake water during the summer.

  12. Seismic Imaging of a Nascent Batholith in the Central Andes

    NASA Astrophysics Data System (ADS)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Christensen, D. H.; Mcfarlin, H. L.

    2013-12-01

    Cordilleran mountain belts, such as the modern central Andes and Mesozoic western North American Cordillera formed in regions of significant upper plate compression and were punctuated by high flux magmatic events that coalesced into large composite batholiths. Unlike the North American Cordillera, compressive mountain building is still active in the central Andes and any large modern batholith still at depth must be inferred from surface volcanics and geophysical data. In the Andes it has been suggested that a modern batholith exists beneath the Altiplano-Puna Volcanic Complex (APVC), the location of a 11-1 Ma ignimbrite flare-up, however, the magmatic underpinnings has only been geophysically investigated in a few widely spaced locations and a migmatite zone of crustal melt with minimal mantle input remains a viable competing interpretation. We present new high-resolution 3-D seismic images of the APVC crust based on a joint inversion of ambient noise surface-wave dispersion data and receiver functions from broadband stations and identify a shallow (<20 km depth) low-velocity body that we interpret as a magmatic mush zone, the Altiplano-Puna Mush Body (APMB). Below the APMB, we observe near-vertical zones of low velocity that bifurcate near the base of the crust with one arm of low velocity migrating under the main volcanic arc and a second separate arm of low velocity below the voluminous backarc volcanism. Previous attenuation tomography studies have traced these zones through the mantle where they intersect the top of the subducting Nazca slab at locations with elevated seismic activity, providing strong evidence that the deeper near-vertical zones of low velocity we are imaging are related to dewatering of the slab and associated mantle-sourced melt pathways. Based on these considerations, we suggest the ~200 km diameter and ~20 km thick body is a nascent silicic batholith compatible with the magma mush model of batholith formation. The direct imaging of this

  13. Ancient ice islands in salt lakes of the central andes.

    PubMed

    Hurlbert, S H; Chang, C C

    1984-04-20

    Massive blocks of freshwater ice and frozen sediments protrude from shallow, saline lakes in the Andes of southwestern Bolivia and northeastern Chile. These ice islands range up to 1.5 kilometers long, stand up to 7 meters above the water surface, and may extend out tens of meters and more beneath the unfrozen lake sediments. The upper surfaces of the islands are covered with dry white sediments, mostly aragonite or calcite. The ice blocks may have formed by freezing of the fresh pore water of lake sediments during the "little ice age." The largest blocks are melting rapidly because of possibly recent increases in geothermal heat flux through the lake bottom and undercutting by warm saline lake water during the summer.

  14. Paleoindian settlement of the high-altitude Peruvian Andes.

    PubMed

    Rademaker, Kurt; Hodgins, Gregory; Moore, Katherine; Zarrillo, Sonia; Miller, Christopher; Bromley, Gordon R M; Leach, Peter; Reid, David A; Álvarez, Willy Yépez; Sandweiss, Daniel H

    2014-10-24

    Study of human adaptation to extreme environments is important for understanding our cultural and genetic capacity for survival. The Pucuncho Basin in the southern Peruvian Andes contains the highest-altitude Pleistocene archaeological sites yet identified in the world, about 900 meters above confidently dated contemporary sites. The Pucuncho workshop site [4355 meters above sea level (masl)] includes two fishtail projectile points, which date to about 12.8 to 11.5 thousand years ago (ka). Cuncaicha rock shelter (4480 masl) has a robust, well-preserved, and well-dated occupation sequence spanning the past 12.4 thousand years (ky), with 21 dates older than 11.5 ka. Our results demonstrate that despite cold temperatures and low-oxygen conditions, hunter-gatherers colonized extreme high-altitude Andean environments in the Terminal Pleistocene, within about 2 ky of the initial entry of humans to South America. PMID:25342802

  15. Complex brittle deformation pattern along the Southern Patagonian Andes (Argentina)

    NASA Astrophysics Data System (ADS)

    Barberón, Vanesa; Sue, Christian; Ronda, Gonzalo; Ghiglione, Matías

    2016-04-01

    The Southern Patagonian Andes is located in the southern extreme of the Pacific subduction zone, where the Antartic oceanic plate sinks underneath South America. The history of the area begins with compression during Paleozoic, Jurassic extension associated to the rift and opening of the South Atlantic Ocean, then a sag stage in the Lower Cretaceous followed by a foreland phase as a result of plate tectonics (Ghiglione et al., 2016). The kinematic study is concentrated in the Argentinean foothills, between 46°40' and 48° SL. We measured around 800 fault planes and their striaes with the sense of movement in order to characterize the stress field. The software used to make the stress inversion were Tensor (Delvaux, 2011) and Multiple Inverse Method MIM (Yamaji et al., 2011). The stress field map was built with the results of the MIM. We present new data from 48 sites located in the northern sector of the Southern Patagonian Andes. The measurements were made in several rocks from Paleozoic to Lower Cretaceous, even though most were taken in pyroclastic jurassic rocks from El Quemado Complex. Paleostress tensors obtained are mostly strike-slip, although a 25% is normal and there are a few compresional. The pattern of faults found is complex. In some sites the tensor can be locally linked to satellite images and observations from the field or be related to a major thrust front. There is no clear correlation between the age and/or lithology with the tensor since the youngest rocks measured are Lower Cretaceous. Probably there are several generations of family faults connected to different and recent tectonic phases then the paleostress tensors might correspond to the latest tectonic events.

  16. Deglaciation and Holocene climate change in the western Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Weng, Chengyu; Bush, Mark B.; Curtis, Jason H.; Kolata, Alan L.; Dillehay, Tom D.; Binford, Michael W.

    2006-07-01

    Pollen, charcoal, magnetic susceptibility, and bulk density data provide the first paleoecological record spanning the last 33,000 years from the western cordillera of the Peruvian Andes. Sparse super-puna vegetation existed before 30,000 cal yr B.P. around Lake Compuerta (3950 m elevation), prior to a sedimentary hiatus that lasted until c. 16,200 cal yr B.P. When sedimentation resumed, a glacial foreland or super-puna flora is represented in which Polylepis was a significant element. Glacial outwash, marked by high sedimentary magnetic susceptibility, increased from c.16,200 cal yr B.P. and reached a peak at c. 13,200 cal yr B.P. Between c. 12,500 cal yr B.P. and 10,000 cal yr B.P., magnetic susceptibility was reduced. Vegetation shifts suggest a cool dry time, consistent with regional descriptions of the Younger Dryas event. Deglaciation resumes by 10,000 cal yr B.P. and the last ice is lost from the catchment at ˜7500 cal yr B.P. During the early Holocene warm and dry period between 10,000 and 5500 cal yr B.P., Alnus expanded in downslope forests. Alnus declined in abundance at 5500 cal yr B.P. when wetter and cooler conditions returned and human activity intensified. Maize ( Zea mays) pollen first occurred in the core at ˜2600 cal yr B.P., indicating a minimum age for local agriculture. An increase in Alnus pollen abundance at ˜1000 cal yr B.P. could be due to human activity or perhaps due to a regional climate change associated with cultural turnover elsewhere in the Andes at this time.

  17. PROTOPLANETARY DISK STRUCTURE WITH GRAIN EVOLUTION: THE ANDES MODEL

    SciTech Connect

    Akimkin, V.; Wiebe, D.; Pavlyuchenkov, Ya.; Zhukovska, S.; Semenov, D.; Henning, Th.; Vasyunin, A.; Birnstiel, T. E-mail: dwiebe@inasan.ru E-mail: zhukovska@mpia.de E-mail: henning@mpia.de E-mail: tbirnstiel@cfa.harvard.edu

    2013-03-20

    We present a self-consistent model of a protoplanetary disk: 'ANDES' ('AccretioN disk with Dust Evolution and Sedimentation'). ANDES is based on a flexible and extendable modular structure that includes (1) a 1+1D frequency-dependent continuum radiative transfer module, (2) a module to calculate the chemical evolution using an extended gas-grain network with UV/X-ray-driven processes and surface reactions, (3) a module to calculate the gas thermal energy balance, and (4) a 1+1D module that simulates dust grain evolution. For the first time, grain evolution and time-dependent molecular chemistry are included in a protoplanetary disk model. We find that grain growth and sedimentation of large grains onto the disk midplane lead to a dust-depleted atmosphere. Consequently, dust and gas temperatures become higher in the inner disk (R {approx}< 50 AU) and lower in the outer disk (R {approx}> 50 AU), in comparison with the disk model with pristine dust. The response of disk chemical structure to the dust growth and sedimentation is twofold. First, due to higher transparency a partly UV-shielded molecular layer is shifted closer to the dense midplane. Second, the presence of big grains in the disk midplane delays the freeze-out of volatile gas-phase species such as CO there, while in adjacent upper layers the depletion is still effective. Molecular concentrations and thus column densities of many species are enhanced in the disk model with dust evolution, e.g., CO{sub 2}, NH{sub 2}CN, HNO, H{sub 2}O, HCOOH, HCN, and CO. We also show that time-dependent chemistry is important for a proper description of gas thermal balance.

  18. Investigating gravity waves and mesospheric temperature variability over the Andes Mountains

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P.; Zhao, Y.; Pugmire, J.; Criddle, N.; Swenson, G. R.; Liu, A. Z.; Hecht, J. H.

    2011-12-01

    The Andes region provides an excellent natural laboratory for investigating gravity wave influences on the Upper Mesospheric and Lower Thermospheric (MLT) dynamics with dominant gravity wave forcing expected from deep convection during the summer months replaced by strong orographic forcing during the wintertime, due to intense prevailing zonal winds blowing over the towering Andes mountain range. The instrument suite that comprised the very successful Maui-MALT program (2000-2005) was relocated to a new Andes Lidar Observatory (ALO) located high in the Andes mountains (2,520 m) at Cerro Pachon, Chile (30.3°S, 70.7°W). As part of this instrument set the Utah State University (USU) Mesospheric Temperature Mapper (MTM) has operated continuously over the past two years (August 2009-to date) measuring the nocturnal near infrared OH(6,2) band and the O2(0,1) Atmospheric band intensity and temperature perturbations to investigate a broad range of mesospheric wave forcings, their seasonal variability and effects on the MLT environment over the Andes. This presentation focuses on the strong variability observed from this site using collaborative investigations of selected wave events, including exceptionally large tidal perturbations (70-100 K), unusual "jumps" in OH/O2 temperature possibly associated with wave breaking, mesospheric bore events, and new evidence for quasi-stationary gravity waves, all illustrating the strong wave activity and its diversity over the Andes.

  19. Spontaneously settled refugees in Northwestern Province, Zambia.

    PubMed

    Freund, P J; Kalumba, K

    1986-01-01

    The UN High Commissioner for Refugees (UNHCR) commissioned researchers from the University of Zambia to conduct a socioeconomic survey and census of "spontaneously settled" Zairean and Angolan refugees in the Northwestern Province of Zambia in 1982. The sample consisted of 188 Angolans, 201 Zaireans, and 2 South Africans. The difficulties experienced by refugees in Northwestern Province in achieving integration were related to a combination of factors including the lack of a clear national policy on refugees and refugee status, a national concern for maintaining security, the popular belief that aliens are responsible for an increasing crime rate, the desire by immigration officials for stricter laws to control alien infiltration, conflict between traditional and modern leaders, and Zambia's deteriorating economic situation. In spite of the problems described, the integration of refugees into existing communities is a desirable goal and should be encouraged. One should not assume that self-settling refugees are able to live with ethnic kin, receive assistance and hospitality, and thus are better off than those in camps. The Zambian case provides ample evidence that integration is not easy even with kin support, shared ethnicity, language, and historical connections. Moreover, given the fact that Zambia will continue to receive refugees it is vital that there is a well defined refugee policy and an administrative mechanism for implementing that policy at all levels. This will be particularly important in Zambia as it will undoubtedly continue to receive large influxes of refugees, from countries such as Namibia, Uganda, Angola, Mozambique, and South Africa.

  20. Spontaneously settled refugees in Northwestern Province, Zambia.

    PubMed

    Freund, P J; Kalumba, K

    1986-01-01

    The UN High Commissioner for Refugees (UNHCR) commissioned researchers from the University of Zambia to conduct a socioeconomic survey and census of "spontaneously settled" Zairean and Angolan refugees in the Northwestern Province of Zambia in 1982. The sample consisted of 188 Angolans, 201 Zaireans, and 2 South Africans. The difficulties experienced by refugees in Northwestern Province in achieving integration were related to a combination of factors including the lack of a clear national policy on refugees and refugee status, a national concern for maintaining security, the popular belief that aliens are responsible for an increasing crime rate, the desire by immigration officials for stricter laws to control alien infiltration, conflict between traditional and modern leaders, and Zambia's deteriorating economic situation. In spite of the problems described, the integration of refugees into existing communities is a desirable goal and should be encouraged. One should not assume that self-settling refugees are able to live with ethnic kin, receive assistance and hospitality, and thus are better off than those in camps. The Zambian case provides ample evidence that integration is not easy even with kin support, shared ethnicity, language, and historical connections. Moreover, given the fact that Zambia will continue to receive refugees it is vital that there is a well defined refugee policy and an administrative mechanism for implementing that policy at all levels. This will be particularly important in Zambia as it will undoubtedly continue to receive large influxes of refugees, from countries such as Namibia, Uganda, Angola, Mozambique, and South Africa. PMID:12267853

  1. First results of a high resolution reflection seismic survey of the Central Northern Venezuelan Shelf

    NASA Astrophysics Data System (ADS)

    Avila, J.; van Welden, A.; Audemard, F.; de Batist, M.; Beck, C.; Scientific Party, G.

    2008-05-01

    . The main SSF fault is not clearly expressed in all profiles as a clear rupture of the sea floor sediments but rather as highly deformed zones. Our data set, also evidences preliminary, due to relatively wide spacing fo the seismic grid- the interest of the studied areas for the investigation of regional natural hazards (climatic, seismo-tectonic), and of the impact of sea level changes in the southeastern Caribbean. This project was funded by FONACIT project PI-2003000090 and French-Venezuelan ECOS-Nord scientific exchange program.

  2. Kinetic, Mutational, and Structural Studies of the Venezuelan Equine Encephalitis Virus Nonstructural Protein 2 Cysteine Protease.

    PubMed

    Hu, Xin; Compton, Jaimee R; Leary, Dagmar H; Olson, Mark A; Lee, Michael S; Cheung, Jonah; Ye, Wenjuan; Ferrer, Mark; Southall, Noel; Jadhav, Ajit; Morazzani, Elaine M; Glass, Pamela J; Marugan, Juan; Legler, Patricia M

    2016-05-31

    The Venezuelan equine encephalitis virus (VEEV) nonstructural protein 2 (nsP2) cysteine protease (EC 3.4.22.-) is essential for viral replication and is involved in the cytopathic effects (CPE) of the virus. The VEEV nsP2 protease is a member of MEROPS Clan CN and characteristically contains a papain-like protease linked to an S-adenosyl-l-methionine-dependent RNA methyltransferase (SAM MTase) domain. The protease contains an alternative active site motif, (475)NVCWAK(480), which differs from papain's (CGS(25)CWAFS), and the enzyme lacks a transition state-stabilizing residue homologous to Gln-19 in papain. To understand the roles of conserved residues in catalysis, we determined the structure of the free enzyme and the first structure of an inhibitor-bound alphaviral protease. The peptide-like E64d inhibitor was found to bind beneath a β-hairpin at the interface of the SAM MTase and protease domains. His-546 adopted a conformation that differed from that found in the free enzyme; one or both of the conformers may assist in leaving group departure of either the amine or Cys thiolate during the catalytic cycle. Interestingly, E64c (200 μM), the carboxylic acid form of the E64d ester, did not inhibit the nsP2 protease. To identify key residues involved in substrate binding, a number of mutants were analyzed. Mutation of the motif residue, N475A, led to a 24-fold reduction in kcat/Km, and the conformation of this residue did not change after inhibition. N475 forms a hydrogen bond with R662 in the SAM MTase domain, and the R662A and R662K mutations both led to 16-fold decreases in kcat/Km. N475 forms the base of the P1 binding site and likely orients the substrate for nucleophilic attack or plays a role in product release. An Asn homologous to N475 is similarly found in coronaviral papain-like proteases (PLpro) of the Severe Acute Respiratory Syndrome (SARS) virus and Middle East Respiratory Syndrome (MERS) virus. Mutation of another motif residue, K480A, led to a 9

  3. Hemostatic properties of Venezuelan Bothrops snake venoms with special reference to Bothrops isabelae venom.

    PubMed

    Rodríguez-Acosta, Alexis; Sánchez, Elda E; Márquez, Adriana; Carvajal, Zoila; Salazar, Ana M; Girón, María E; Estrella, Amalid; Gil, Amparo; Guerrero, Belsy

    2010-11-01

    In Venezuela, Bothrops snakes are responsible for more than 80% of all recorded snakebites. This study focuses on the biological and hemostatic characteristics of Bothrops isabelae venom along with its comparative characteristics with two other closely related Bothrops venoms, Bothrops atrox and Bothrops colombiensis. Electrophoretic profiles of crude B. isabelae venom showed protein bands between 14 and 100 kDa with the majority in the range of 14-31 kDa. The molecular exclusion chromatographic profile of this venom contains five fractions (F1-F5). Amidolytic activity evaluation evidenced strong thrombin-like followed by kallikrein-like activities in crude venom and in fractions F1 and F2. The fibrinogenolytic activity of B. isabelae venom at a ratio of 100:1 (fibrinogen/venom) induced a degradation of A alpha and B beta chains at 15 min and 2 h, respectively. At a ratio of 100:10, a total degradation of A alpha and B beta chains at 5 min and of gamma chains at 24 h was apparent. This current study evidences one of rarely reported for Bothrops venoms, which resembles the physiologic effect of plasmin. B. isabelae venom as well as F2 and F3 fractions, contain fibrinolytic activity on fibrin plate of 36, 23.5 and 9.45 mm(2)/microg, respectively using 25 microg of protein. Crude venom and F1 fraction showed gelatinolytic activity. Comparative analysis amongst Venezuelan bothropoid venoms, evidenced that the LD(50) of B. isabelae (5.9 mg/kg) was similar to B. atrox-Puerto Ayacucho 1 (6.1 mg/kg) and B. colombiensis-Caucagua (5.8 mg/kg). B. isabelae venom showed minor hemorrhagic activity, whereas B. atrox-Parguasa (Bolivar state) was the most hemorrhagic. In this study, a relative high thrombin-like activity was observed in B. colombiensis venoms (502-568 mUA/min/mg), and a relative high factor Xa-like activity was found in B. atrox venoms (126-294 mUA/min/mg). Fibrinolytic activity evaluated with 10 microg protein, showed that B. isabelae venom contained higher

  4. Hemostatic properties of Venezuelan Bothrops snake venoms with special reference to Bothrops isabelae venom.

    PubMed

    Rodríguez-Acosta, Alexis; Sánchez, Elda E; Márquez, Adriana; Carvajal, Zoila; Salazar, Ana M; Girón, María E; Estrella, Amalid; Gil, Amparo; Guerrero, Belsy

    2010-11-01

    In Venezuela, Bothrops snakes are responsible for more than 80% of all recorded snakebites. This study focuses on the biological and hemostatic characteristics of Bothrops isabelae venom along with its comparative characteristics with two other closely related Bothrops venoms, Bothrops atrox and Bothrops colombiensis. Electrophoretic profiles of crude B. isabelae venom showed protein bands between 14 and 100 kDa with the majority in the range of 14-31 kDa. The molecular exclusion chromatographic profile of this venom contains five fractions (F1-F5). Amidolytic activity evaluation evidenced strong thrombin-like followed by kallikrein-like activities in crude venom and in fractions F1 and F2. The fibrinogenolytic activity of B. isabelae venom at a ratio of 100:1 (fibrinogen/venom) induced a degradation of A alpha and B beta chains at 15 min and 2 h, respectively. At a ratio of 100:10, a total degradation of A alpha and B beta chains at 5 min and of gamma chains at 24 h was apparent. This current study evidences one of rarely reported for Bothrops venoms, which resembles the physiologic effect of plasmin. B. isabelae venom as well as F2 and F3 fractions, contain fibrinolytic activity on fibrin plate of 36, 23.5 and 9.45 mm(2)/microg, respectively using 25 microg of protein. Crude venom and F1 fraction showed gelatinolytic activity. Comparative analysis amongst Venezuelan bothropoid venoms, evidenced that the LD(50) of B. isabelae (5.9 mg/kg) was similar to B. atrox-Puerto Ayacucho 1 (6.1 mg/kg) and B. colombiensis-Caucagua (5.8 mg/kg). B. isabelae venom showed minor hemorrhagic activity, whereas B. atrox-Parguasa (Bolivar state) was the most hemorrhagic. In this study, a relative high thrombin-like activity was observed in B. colombiensis venoms (502-568 mUA/min/mg), and a relative high factor Xa-like activity was found in B. atrox venoms (126-294 mUA/min/mg). Fibrinolytic activity evaluated with 10 microg protein, showed that B. isabelae venom contained higher

  5. Ethnobotanical knowledge is vastly under-documented in northwestern South America.

    PubMed

    Cámara-Leret, Rodrigo; Paniagua-Zambrana, Narel; Balslev, Henrik; Macía, Manuel J

    2014-01-01

    A main objective of ethnobotany is to document traditional knowledge about plants before it disappears. However, little is known about the coverage of past ethnobotanical studies and thus about how well the existing literature covers the overall traditional knowledge of different human groups. To bridge this gap, we investigated ethnobotanical data-collecting efforts across four countries (Colombia, Ecuador, Peru, Bolivia), three ecoregions (Amazon, Andes, Chocó), and several human groups (including Amerindians, mestizos, and Afro-Americans). We used palms (Arecaceae) as our model group because of their usefulness and pervasiveness in the ethnobotanical literature. We carried out a large number of field interviews (n = 2201) to determine the coverage and quality of palm ethnobotanical data in the existing ethnobotanical literature (n = 255) published over the past 60 years. In our fieldwork in 68 communities, we collected 87,886 use reports and documented 2262 different palm uses and 140 useful palm species. We demonstrate that traditional knowledge on palm uses is vastly under-documented across ecoregions, countries, and human groups. We suggest that the use of standardized data-collecting protocols in wide-ranging ethnobotanical fieldwork is a promising approach for filling critical information gaps. Our work contributes to the Aichi Biodiversity Targets and emphasizes the need for signatory nations to the Convention on Biological Diversity to respond to these information gaps. Given our findings, we hope to stimulate the formulation of clear plans to systematically document ethnobotanical knowledge in northwestern South America and elsewhere before it vanishes.

  6. Ethnobotanical Knowledge Is Vastly Under-Documented in Northwestern South America

    PubMed Central

    Cámara-Leret, Rodrigo; Paniagua-Zambrana, Narel; Balslev, Henrik; Macía, Manuel J.

    2014-01-01

    A main objective of ethnobotany is to document traditional knowledge about plants before it disappears. However, little is known about the coverage of past ethnobotanical studies and thus about how well the existing literature covers the overall traditional knowledge of different human groups. To bridge this gap, we investigated ethnobotanical data-collecting efforts across four countries (Colombia, Ecuador, Peru, Bolivia), three ecoregions (Amazon, Andes, Chocó), and several human groups (including Amerindians, mestizos, and Afro-Americans). We used palms (Arecaceae) as our model group because of their usefulness and pervasiveness in the ethnobotanical literature. We carried out a large number of field interviews (n = 2201) to determine the coverage and quality of palm ethnobotanical data in the existing ethnobotanical literature (n = 255) published over the past 60 years. In our fieldwork in 68 communities, we collected 87,886 use reports and documented 2262 different palm uses and 140 useful palm species. We demonstrate that traditional knowledge on palm uses is vastly under-documented across ecoregions, countries, and human groups. We suggest that the use of standardized data-collecting protocols in wide-ranging ethnobotanical fieldwork is a promising approach for filling critical information gaps. Our work contributes to the Aichi Biodiversity Targets and emphasizes the need for signatory nations to the Convention on Biological Diversity to respond to these information gaps. Given our findings, we hope to stimulate the formulation of clear plans to systematically document ethnobotanical knowledge in northwestern South America and elsewhere before it vanishes. PMID:24416449

  7. Tectonic control on denudation rates in the central Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Zeilinger, Gerold; Kober, Florian; Hippe, Kristina; Lendzioch, Theodora; Grischott, Reto; Pillco Zolá, Ramiro; Christl, Markus

    2013-04-01

    Effects of a positive feedback loop between erosion and tectonics have been shown by analogue and numerical models and have been inferred from field observations at the scale of mountain ranges. We present new data from the Bolivian Andes supporting these observations, although common geomorphic parameters do not indicate a simple correlation. The upper Rio Grande segment, located between Cochabamba, Santa Cruz and Sucre, drains a major catchment in the central Bolivian Cordillera, from the Eastern Cordillera (EC) in the W, through the Interandean Zone (IAZ) and the Subandes (SA) in the E. The catchment covers an area of 58939 km² with an altitude range from 400 to 5150 m above sea level. Geologically, the Bolivian Andes comprise (from W to E) the Altiplano, the EC, the IAZ and the SA fold and thrust belts. The Altiplano represents an almost perfectly closed basin with distinct barriers defined by the Western Cordillera and Eastern Cordillera. The Rio Grande does not reach the Altiplano (unlike Rio La Paz and Rio Consata) but has its western drainage divide along the high peaks of the EC that experienced a period of intense shortening between Late Oligocene and Miocene. Near Cochabamba, the EC comprises metasedimentary siliciclastic rocks of Ordovician age. These rocks are overlain by Cretaceous to Paleocene and / or Neogene sediments with an angular unconformity. The IAZ and SA form an east-vergent fold and thrust belt and comprise Paleozoic and Mesozoic units. Farther east, the structures of the SA progressively include Neogene foreland strata of the Chaco foreland basin. The Chaco basin rests on the Brazilian shield east of the Subandean Belt and forms the modern foreland basin, where the lower Rio Grande catchment is sited. We obtained 58 cosmogenic 10Be catchment wide denudation rates for the Rio Grande catchments upstream of Abapó. They range from 7 mm/kyr to 1550 mm/kyr thus integrating at maximum over the last 10.000 years, with a mean of 262 mm/kyr. In

  8. Large slope failures in the La Paz basin, Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Roberts, N. J.; Hermanns, R. L.; Rabus, B.; Guzmán, M. A.; Minaya, E.; Clague, J. J.

    2014-12-01

    The La Paz basin in the eastern Bolivian Andes has been a hotspot for large-scale, deep-seated gravitational slope deformation during the Holocene. In less than 2 Ma, a network of steep-sided valleys up to 800 m deep formed in sediments of the Altiplano Plateau and underlying basement rocks. We characterize the distribution, extent, mechanisms, and modern activity of large-scale failures within this landscape using optical image interpretation, existing geologic maps, synthetic RADAR interferometry (InSAR), and field investigation. Deposits of nearly 20 landslides larger than 100 Mm3 occur within the basin. Most failures have occurred in weakly lithified Late Miocene to Pliocene sedimentary rocks and include earth flows, translational and rotational landslides, and plug flows. Failures in underlying tectonized Paleozoic sedimentary rocks include bedding-parallel rockslides. The largest failure is the 3 km3 Achcocalla earth flow (ca. 11 ka BP), which ran out ~20 km. Other dated events span the period from the early Holocene to nearly the Colonial historic period. InSAR results show that many large slope failures, including the Achocalla earth flow, are currently moving at rates of a few centimeters to a few decimeters per year. Rapid deposition, shallow burial, and rapid incision of the basin fills produced steep slopes in weak geologic materials that, coupled with groundwater discharge from the valley walls, are the primary controls on instability. In contrast, the Altiplano surface has changed little in 2 Ma and the adjacent slopes of the Cordilleran Real, although steep, are relatively stable. Of the over 100 landslides that have occurred in the city of La Paz since the early twentieth century, most are at the margins of large, deep-seated prehistoric failures, and two of the most damaging historic landslides (Hanko-Hanko, 1582; Pampahasi, 2011) were large-scale reactivations of previously failed slopes. Improved understanding of large, deep-seated landslides in

  9. Guillain-Barré syndrome in northwestern China.

    PubMed

    Jiang, W; Wang, H D; Huang, Y G; Wan, Q; Xu, Y; Wu, B R

    2001-01-01

    We reviewed 100 patients with Guillan-Barré syndrome (GBS) from 1994 to 2000 from northwestern China. We examined clinical and electro-diagnostics features and compared them to patients from Europe, North America and northern China. Results indicated that among 100 patients with GBS, the demyelinating pattern was present in 51 patients, the axonal pattern in 25 patients, and 8 patients were inexcitable, 12 patients equivocal and 4 patients normal. The electrophysiological and clinical features of various subtypes of GBS in northwestern China seemed to be different in some ways from those in western countries and in northern China. However, in northwestern China, the demyelinating pattern is the major electrophysiological subtype.

  10. The northwestern ejecta knot in SN 1006

    NASA Astrophysics Data System (ADS)

    Broersen, S.; Vink, J.; Miceli, M.; Bocchino, F.; Maurin, G.; Decourchelle, A.

    2013-04-01

    Aims: We want to probe the physics of fast collision-less shocks in supernova remnants. We are interested in the non-equilibration of temperatures and particle acceleration. Specifically, we aim to measure the oxygen temperature with regards to the electron temperature. In addition, we search for synchrotron emission in the northwestern thermal rim. Methods: This study is part of a dedicated deep observational project of SN 1006 using XMM-Newton, which provides us with the currently best resolution spectra of the bright northwestern oxygen knot. We aim to use the reflection grating spectrometer to measure the thermal broadening of the O vii line triplet by convolving the emission profile of the remnant with the response matrix. Results: The line broadening was measured as σe = 2.4 ± 0.3 eV, corresponding to an oxygen temperature of 275-63+72 keV. From the EPIC spectra we obtain an electron temperature of 1.35 ± 0.10 keV. The difference in temperature between the species provides further evidence of non-equilibration of temperatures in a shock. In addition, we find evidence of a bow shock that emits X-ray synchrotron radiation, which is at odds with the general idea that because of the magnetic field orientation only in the NE and SW region, X-ray synchrotron radiation should be emitted. We find an unusual Hα and X-ray synchrotron geometry, in that the Hα emission peaks downstream of the synchrotron emission. This may be an indication of a peculiar Hα shock in which the density is lower and the neutral fraction is higher than in other supernova remnants, resulting in a peak in Hα emission further downstream of the shock.

  11. Induction of neutralizing antibodies to Hendra and Nipah glycoproteins using a Venezuelan equine encephalitis virus in vivo expression system.

    PubMed

    Defang, Gabriel N; Khetawat, Dimple; Broder, Christopher C; Quinnan, Gerald V

    2010-12-16

    The emergence of Hendra Virus (HeV) and Nipah Virus (NiV) which can cause fatal infections in both animals and humans has triggered a search for an effective vaccine. Here, we have explored the potential for generating an effective humoral immune response to these zoonotic pathogens using an alphavirus-based vaccine platform. Groups of mice were immunized with Venezuelan equine encephalitis virus replicon particles (VRPs) encoding the attachment or fusion glycoproteins of either HeV or NiV. We demonstrate the induction of highly potent cross-reactive neutralizing antibodies to both viruses using this approach. Preliminary study suggested early enhancement in the antibody response with use of a modified version of VRP. Overall, these data suggest that the use of an alphavirus-derived vaccine platform might serve as a viable approach for the development of an effective vaccine against the henipaviruses.

  12. 1,5-Iodonaphthyl azide-inactivated V3526 protects against aerosol challenge with virulent venezuelan equine encephalitis virus.

    PubMed

    Gupta, Paridhi; Sharma, Anuj; Spurgers, Kevin B; Bakken, Russell R; Eccleston, Lori T; Cohen, Jeffrey W; Honnold, Shelley P; Glass, Pamela J; Maheshwari, Radha K

    2016-05-27

    Venezuelan equine encephalitis virus (VEEV) is a New World alphavirus. VEEV is highly infectious in aerosolized form and has been identified as a bio-terrorism agent. There is no licensed vaccine for prophylaxis against VEEV. The current IND vaccine is poorly immunogenic and does not protect against an aerosol challenge with virulent VEEV. We have previously shown that VEEV inactivated by 1,5-iodonaphthyl azide (INA) protects against footpad challenge with virulent VEEV. In this study, we inactivated an attenuated strain of VEEV, V3526, with INA and evaluated its protective efficacy against aerosol challenge with wild type VEEV. We demonstrated that among three routes of immunization, intramuscular immunization with INA-inactivate V3526 (INA-iV3526) provided complete protection against aerosol challenge with virulent VEEV. Our data suggests that INA-iV3526 can be explored further for development as an effective vaccine candidate against aerosol challenge of virulent VEEV. PMID:27129427

  13. Using gas geochemistry to delineate structural compartments and assess petroleum reservoir-filling directions: A Venezuelan case study

    NASA Astrophysics Data System (ADS)

    Márquez, G.; Escobar, M.; Lorenzo, E.; Gallego, J. R.; Tocco, R.

    2013-04-01

    Here we examined the light hydrocarbon and nitrogen content and isotopic signatures of eleven gaseous samples in order to evaluate lateral intra-reservoir continuity in a Venezuelan reservoir in the central area of Lake Maracaibo Basin. At least three single compartments, located in the northern-central and southern parts of the reservoir, are revealed by nitrogen concentrations showing clear step-like compositional breaks. The occurrence of step-breaks was also supported by the isotopic signature of individual hydrocarbon compounds in the range of C1-C4 alkanes. Samples presented only slight differences in N2 and hydrocarbon gas compositions within the central and northern parts of the reservoir, and therefore it was not possible to infer structural barriers in coherence with the geological section. Some oil bulk parameters corroborate gradual changes that provide additional information on the reservoir-filling history, thus suggesting that the lateral physical-chemical equilibrium of fluids was not reached in this reservoir.

  14. Comparative Phylogeography Reveals Cryptic Diversity and Repeated Patterns of Cladogenesis for Amphibians and Reptiles in Northwestern Ecuador

    PubMed Central

    Pyron, R. Alexander; Peñafiel, Nicolás; Romero-Barreto, Paulina; Culebras, Jaime; Bustamante, Lucas; Yánez-Muñoz, Mario H.; Guayasamin, Juan M.

    2016-01-01

    Comparative phylogeography allow us to understand how shared historical circumstances have shaped the formation of lineages, by examining a broad spectrum of co-distributed populations of different taxa. However, these types of studies are scarce in the Neotropics, a region that is characterized by high diversity, complex geology, and poorly understood biogeography. Here, we investigate the diversification patterns of five lineages of amphibians and reptiles, co-distributed across the Choco and Andes ecoregions in northwestern Ecuador. Mitochondrial DNA and occurrence records were used to determine the degree of geographic genetic divergence within species. Our results highlight congruent patterns of parapatric speciation and common geographical barriers for distantly related taxa. These comparisons indicate similar biological and demographic characteristics for the included clades, and reveal the existence of two new species of Pristimantis previously subsumed under P. walkeri, which we describe herein. Our data supports the hypothesis that widely distributed Chocoan taxa may generally experience their greatest opportunities for isolation and parapatric speciation across thermal elevational gradients. Finally, our study provides critical information to predict which unstudied lineages may harbor cryptic diversity, and how geology and climate are likely to have shaped their evolutionary history. PMID:27120100

  15. Comparative Phylogeography Reveals Cryptic Diversity and Repeated Patterns of Cladogenesis for Amphibians and Reptiles in Northwestern Ecuador.

    PubMed

    Arteaga, Alejandro; Pyron, R Alexander; Peñafiel, Nicolás; Romero-Barreto, Paulina; Culebras, Jaime; Bustamante, Lucas; Yánez-Muñoz, Mario H; Guayasamin, Juan M

    2016-01-01

    Comparative phylogeography allow us to understand how shared historical circumstances have shaped the formation of lineages, by examining a broad spectrum of co-distributed populations of different taxa. However, these types of studies are scarce in the Neotropics, a region that is characterized by high diversity, complex geology, and poorly understood biogeography. Here, we investigate the diversification patterns of five lineages of amphibians and reptiles, co-distributed across the Choco and Andes ecoregions in northwestern Ecuador. Mitochondrial DNA and occurrence records were used to determine the degree of geographic genetic divergence within species. Our results highlight congruent patterns of parapatric speciation and common geographical barriers for distantly related taxa. These comparisons indicate similar biological and demographic characteristics for the included clades, and reveal the existence of two new species of Pristimantis previously subsumed under P. walkeri, which we describe herein. Our data supports the hypothesis that widely distributed Chocoan taxa may generally experience their greatest opportunities for isolation and parapatric speciation across thermal elevational gradients. Finally, our study provides critical information to predict which unstudied lineages may harbor cryptic diversity, and how geology and climate are likely to have shaped their evolutionary history. PMID:27120100

  16. Comparative Phylogeography Reveals Cryptic Diversity and Repeated Patterns of Cladogenesis for Amphibians and Reptiles in Northwestern Ecuador.

    PubMed

    Arteaga, Alejandro; Pyron, R Alexander; Peñafiel, Nicolás; Romero-Barreto, Paulina; Culebras, Jaime; Bustamante, Lucas; Yánez-Muñoz, Mario H; Guayasamin, Juan M

    2016-01-01

    Comparative phylogeography allow us to understand how shared historical circumstances have shaped the formation of lineages, by examining a broad spectrum of co-distributed populations of different taxa. However, these types of studies are scarce in the Neotropics, a region that is characterized by high diversity, complex geology, and poorly understood biogeography. Here, we investigate the diversification patterns of five lineages of amphibians and reptiles, co-distributed across the Choco and Andes ecoregions in northwestern Ecuador. Mitochondrial DNA and occurrence records were used to determine the degree of geographic genetic divergence within species. Our results highlight congruent patterns of parapatric speciation and common geographical barriers for distantly related taxa. These comparisons indicate similar biological and demographic characteristics for the included clades, and reveal the existence of two new species of Pristimantis previously subsumed under P. walkeri, which we describe herein. Our data supports the hypothesis that widely distributed Chocoan taxa may generally experience their greatest opportunities for isolation and parapatric speciation across thermal elevational gradients. Finally, our study provides critical information to predict which unstudied lineages may harbor cryptic diversity, and how geology and climate are likely to have shaped their evolutionary history.

  17. Epidemiology of Echinococcus granulosus infection in the central Peruvian Andes.

    PubMed Central

    Moro, P. L.; McDonald, J.; Gilman, R. H.; Silva, B.; Verastegui, M.; Malqui, V.; Lescano, G.; Falcon, N.; Montes, G.; Bazalar, H.

    1997-01-01

    The prevalence of human, canine, and ovine echinococcosis was determined in an endemic area of the Peruvian Andes where control programmes have not been operational since 1980. Prevalence of infection in humans was determined using portable ultrasound, chest X-rays, and an enzyme-linked immunoelectrotransfer blot (EITB) assay. Canine and ovine echinococcal prevalence was determined by microscopic stool examinations following arecoline purging for tapeworm detection and by examination of the viscera from slaughtered livestock animals, respectively. The prevalence among 407 humans surveyed was 9.1%. The frequency of disease in the liver, lung, and in both organs was 3.4%, 2.0%, and 0.2%, respectively. Portable ultrasound or portable chest X-ray has shown that, compared to adults, children under 11 years had significantly higher seropositive rates without evidence of hydatid disease (P < 0.05). Among the 104 dogs inspected for echinococcus after arecoline purging, 33 (32%) were positive for adult tapeworms. Among the 117 sheep slaughtered at the local abattoir, 102 (87%) had hydatid cysts. The prevalence of human hydatidosis in this endemic area of Peru is one of the highest in the world and nearly five times higher than previously reported in 1980. An increase in echinococcosis prevalence may result after premature cessation of control programmes. PMID:9509628

  18. On recent measurements from the Andes Lidar Observatory

    NASA Astrophysics Data System (ADS)

    Liu, Alan Z.; Snively, Jonathan; Heale, Christopher; Cao, Bing

    2016-07-01

    The Andes Lidar Observatory is an upper atmosphere observatory located in Cerro Pachón, Chile (30.3S, 70.7W). It houses a Na Wind/Temperature Lidar, an all sky airglow imager, a mesospheric temperature mapper, an infrared imager and a meteor radar. This suite of instrumentation provides comprehensive measurements of the mesopause region and enables detailed study of wave dynamics. With the recent upgrade of the Na lidar, many complex dynamic processes were observed and resolved in detail. I will present several intriguing phenomena seen in the lidar measurement from recent campaigns, and a detailed analysis of a complex wave propagation event, which involved a large vertical wind oscillation exceeding 10 m/s. A nonlinear gravity wave model was able to reproduce most of the observed features. The results suggest that the wave experienced partial reflections at two altitudes and a critical layer in between, resulting in large vertical wind amplitude and multi-layer distribution of wave energy.

  19. [Medical education at Universidad de los Andes, Santiago, Chile].

    PubMed

    Orrego Vicuña, F

    1997-07-01

    Universidad de los Andes School of Medicine started in 1991 with a new medical curriculum aimed at providing a medical education for its students, that is, it attempts to give, together with technical proficiency in medical matters, formation of character and a strong ethical attitude. The curriculum lasts for seven years: five of basic, pre-clinical and clinical theoretical and practical courses, followed by two years of internships in Internal Medicine, Surgery, Obstetrics and Pediatrics, plus a four month period of an elective internship. The courses have an integrated design, in which each matter is presented from multiple perspectives, e.g. in Internal Medicine together with the clinical aspects of disease, the pathophysiology and the pharmacology of the drugs used are presented. Also the Pathology of each disease is given in coordination in the Pathology course. General educational matters such as Anthropology, Psychology, Origin of Living Beings, Theology and Medical Ethics are interspersed in the curriculum. An important feature is the personal counselling system, in which each student may choose an academic counsellor and discuss with him (her) the subjects of his choosing. Clinical practice is given in a system that includes five hospitals and five private clinics that range from general medical practice to Psychiatry or Ophthalmology.

  20. Membrane triangles with corner drilling freedoms. II - The ANDES element

    NASA Technical Reports Server (NTRS)

    Felippa, Carlos A.; Militello, Carmelo

    1992-01-01

    This is the second article in a three-part series on the construction of 3-node, 9-dof membrane elements with normal-to-its-plane rotational freedoms (the so-called drilling freedoms) using parametrized variational principles. In this part, one such element is derived within the context of the assumed natural deviatoric strain (ANDES) formulation. The higher-order strains are obtained by constructing three parallel-to-sides pure-bending modes from which natural strains are obtained at the corner points and interpolated over the element. To attain rank sufficiency, an additional higher-order 'torsional' mode, corresponding to equal hierarchical rotations at each corner with all other motions precluded, is incorporated. The resulting formulation has five free parameters. When these parameters are optimized against pure bending by energy balance methods, the resulting element is found to coalesce with the optimal EFF element derived in Part I. Numerical integration as a strain filtering device is found to play a key role in this achievement.

  1. Paleomagnetism of Permian and Triassic rock, central Chilean Andes

    NASA Astrophysics Data System (ADS)

    Forsythe, Randall D.; Kent, Dennis V.; Mpodozis, Constantino; Davidson, John

    The first paleomagnetic data from Permian and Triassic formations west of the Andean divide are presented. Four formations of Permian or Triassic age in the central Chilean Andes have been investigated: two are located in the coastal ranges, and two are in the main cordillera. Of the formations in the main cordillera (Pastos Blancos and Matahuaico formations), only the Pastos Blancos Formation has yielded characteristic directions. While a fold test is absent, magnetizations are most likely secondary and yield pre-tilt corrected concordant inclinations, but yield declinations discordant 30° clockwise in comparison to the South American apparent polar wander path. Both formations from the coastal ranges (Cifuncho and Pichidangui formations) yielded stable directions. Postfolding magnetizations in the Cifuncho Formation also show declinations discordant 30° clockwise and concordant inclinations. The Pichidangui Formation has two stable components: one of postfolding age is concordant to apparent polar wander path data, and one of probable prefolding (Late Triassic) age is concordant in declination, but discordant in inclination. Further work is needed to better define the prefolding magnetizations in the Pichidangui Formation, but at present these preliminary results are the first paleomagnetic signs of displaced terranes along the Pacific margin of Chile. If correct, the results suggest that the Pichidangui Formation was some 15° of latitude farther south during the Late Triassic and had likely moved northward to its present latitudinal position with respect to cratonic South America by Middle to Late Jurassic.

  2. Active Folding of the Tame Anticline, Eastern Foothills, Colombian Andes

    NASA Astrophysics Data System (ADS)

    Veloza-Fajardo, G.; Taylor, M. H.; Mora, A.; Stockli, D. F.

    2011-12-01

    We integrate neotectonic mapping and interpretation of seismic reflection profiles to evaluate the kinematics of folding and development of the Quaternary Tame anticline and Cusiana fault at 6.5 N Latitude in the eastern foothills of the Eastern Cordillera of Colombia. The Tame anticline is located approximately 660 km to the east of the Nazca-South America and 810 km to the south of the Caribbean-South America subduction zones plate boundaries in a retroarc foreland basin setting. The Tame anticline is an elongated, N15E trending structure, 14 km long N-S by 6 km wide E-W, that represents the most frontal active structure of the northern Colombian Andes. The Tame fold is related to the east-directed Cusiana fault that day lights to the south. Seismic reflection profiles indicate the Cusiana fault is a listric, west-dipping blind structure. The east flowing antecedent Macaguana creek has incised the Tame fold forming three prominent terrace levels, uplifted approximately 220, 150 and 100 meters, above current river levels. The surfaces were sampled for terrestrial cosmogenic nuclides using the depth profiling approach to account for inheritance. Surface exposure ages from the highest to lowest surfaces are 93.9, 50.8 and 32.4 kyrs at the 1σ level respectively, which were calculated using Monte Carlo methods. Trishear kinematic modeling was used to retrodeform the folding history and based on the surface abandonment ages, we will present shortening rates at millennial timescales.

  3. Over three millennia of mercury pollution in the Peruvian Andes.

    PubMed

    Cooke, Colin A; Balcom, Prentiss H; Biester, Harald; Wolfe, Alexander P

    2009-06-01

    We present unambiguous records of preindustrial atmospheric mercury (Hg) pollution, derived from lake-sediment cores collected near Huancavelica, Peru, the largest Hg deposit in the New World. Intensive Hg mining first began ca. 1400 BC, predating the emergence of complex Andean societies, and signifying that the region served as a locus for early Hg extraction. The earliest mining targeted cinnabar (HgS) for the production of vermillion. Pre-Colonial Hg burdens peak ca. 500 BC and ca. 1450 AD, corresponding to the heights of the Chavín and Inca states, respectively. During the Inca, Colonial, and industrial intervals, Hg pollution became regional, as evidenced by a third lake record approximately 225 km distant from Huancavelica. Measurements of sediment-Hg speciation reveal that cinnabar dust was initially the dominant Hg species deposited, and significant increases in deposition were limited to the local environment. After conquest by the Inca (ca. 1450 AD), smelting was adopted at the mine and Hg pollution became more widely circulated, with the deposition of matrix-bound phases of Hg predominating over cinnabar dust. Our results demonstrate the existence of a major Hg mining industry at Huancavelica spanning the past 3,500 years, and place recent Hg enrichment in the Andes in a broader historical context. PMID:19451629

  4. Use and legacy of mercury in the Andes.

    PubMed

    Cooke, Colin A; Hintelmann, Holger; Ague, Jay J; Burger, Richard; Biester, Harald; Sachs, Julian P; Engstrom, Daniel R

    2013-05-01

    Both cinnabar (HgS) and metallic mercury (Hg(0)) were important resources throughout Andean prehistory. Cinnabar was used for millennia to make vermillion, a red pigment that was highly valued in pre-Hispanic Peru; metallic Hg(0) has been used since the mid-16th century to conduct mercury amalgamation, an efficient process of extracting precious metals from ores. However, little is known about which cinnabar deposits were exploited by pre-Hispanic cultures, and the environmental consequences of Hg mining and amalgamation remain enigmatic. Here we use Hg isotopes to source archeological cinnabar and to fingerprint Hg pollution preserved in lake sediment cores from Peru and the Galápagos Islands. Both pre-Inca (pre-1400 AD) and Colonial (1532-1821 AD) archeological artifacts contain cinnabar that matches isotopically with cinnabar ores from Huancavelica, Peru, the largest cinnabar-bearing district in Central and South America. In contrast, the Inca (1400-1532 AD) artifacts sampled are characterized by a unique Hg isotopic composition. In addition, preindustrial (i.e., pre-1900 AD) Hg pollution preserved in lake sediments matches closely the isotopic composition of cinnabar from the Peruvian Andes. Industrial-era Hg pollution, in contrast, is distinct isotopically from preindustrial emissions, suggesting that pre- and postindustrial Hg emissions may be distinguished isotopically in lake sediment cores. PMID:23597056

  5. Dendrogeomorphic reconstruction of flash floods in the Patagonian Andes

    NASA Astrophysics Data System (ADS)

    Casteller, Alejandro; Stoffel, Markus; Crespo, Sebastián; Villalba, Ricardo; Corona, Christophe; Bianchi, Emilio

    2015-01-01

    Flash floods represent a significant natural hazard in small mountainous catchments of the Patagonian Andes and have repeatedly caused loss to life and infrastructure. At the same time, however, documentary records of past events remain fairly scarce and highly fragmentary in most cases. In this study, we therefore reconstruct the spatiotemporal patterns of past flash flood activity along the Los Cipreses torrent (Neuquén, Argentina) using dendrogeomorphic methods. Based on samples from Austrocedrus chilensis, Pseudotsuga menziesii, and Nothofagus dombeyi, we document 21 flash flood events covering the period A.D. 1890-2009 and reconstruct mean recurrence intervals of events at the level of individual trees being impacted, which varies from 4 to 93 years. Results show that trees tend to be older (younger) in sectors of the torrent with gentler (steeper) slope gradients. Potential triggers of flash floods were analyzed using daily temperature and precipitation data from a nearby weather station. Weather conditions leading to flash floods are abundant precipitations during one to three consecutive days, combined with temperatures above the rain/snow threshold (2 °C) in the whole watershed.

  6. Quaternary Glaciations in the Rio Mendoza Valley, Argentine Andes

    NASA Astrophysics Data System (ADS)

    Espizua, Lydia E.

    1993-09-01

    In the Rio Mendoza valley, five Pleistocene drifts and one Holocene drift are distinguished by multiple relative-age criteria, including surface-rock weathering, development of rock varnish, moraine morphology, soil-profile development, and stratigraphic relationships. Several absolute ages suggest a preliminary chronology. During the oldest (Uspallata) glaciation, a system of valley glaciers flowed 110 km from the Andean drainage divide and 80 km from Cerro Aconcagua to terminate at 1850 m. Drift of this ice advance is older than a widespread tephra dated by fission-track at 360,000 ± 36,000 yr. During the Punta de Vacas advance, ice terminated at 2350 m, while during the subsequent Penitentes advance, the glacier system ended at 2500 m. A travertine layer overlying Penitentes Drift has U-series age of 24,200 ± 2000 yr B.P. The distribution of Horcones Drift, which is inferred to represent the last glacial maximum, delimits an independent ice stream that flowed 22 km down Horcones valley to 2750 m. A later readvance (Almacenes) reached 3250 m. Confluencia Drift is considered to be Neoglacial in age and extends downvalley to 3300 m. The moraine sequence is compared with those studied by Caviedes (1972) along Rio Aconcagua on the Chilean flank of the Andes.

  7. POTENTIAL IMPACTS OF CLIMATE CHANGE ON THE TROPICAL ANDES

    NASA Astrophysics Data System (ADS)

    Soria, Freddy; Kazama, So

    In this paper are investigated the net radiation (Rn) and the potential glacier melt discharge trends in a glacier in the tropical Andes, for the assessment of climate change impacts on the water resources availability in remote regions. It is assessed the applicability of remote sensing techniques, through the performance evaluation of the Surface and Energy Balance algorithm (SEBAL). For the calibration it is used ground data observed on the ablation surface of the Zongo glacier in Bolivia. The potential climate change impacts quantified are on the glacier melt discharge. The inferences are calibrated in the period 2004-2007. Results show that the SEBAL performance is adequate from an engineering perspective (Root Mean Square Error for albedo estimations are 0.15, in average). Climate change impacts for the period 1986-2005 are an increase of 42% in the Rn, and the loss in the glacier ablation area of 37% (both in reference to 1986). The melt from the studied glacier in the period 2004-2007 is estimated to produce a maximum potential energy of 3.1 [MW h] in average per day (dry season), which in the practice can be used to quantify the potential impacts of the climate change in partially glacierized catchments.

  8. Over three millennia of mercury pollution in the Peruvian Andes

    PubMed Central

    Cooke, Colin A.; Balcom, Prentiss H.; Biester, Harald; Wolfe, Alexander P.

    2009-01-01

    We present unambiguous records of preindustrial atmospheric mercury (Hg) pollution, derived from lake-sediment cores collected near Huancavelica, Peru, the largest Hg deposit in the New World. Intensive Hg mining first began ca. 1400 BC, predating the emergence of complex Andean societies, and signifying that the region served as a locus for early Hg extraction. The earliest mining targeted cinnabar (HgS) for the production of vermillion. Pre-Colonial Hg burdens peak ca. 500 BC and ca. 1450 AD, corresponding to the heights of the Chavín and Inca states, respectively. During the Inca, Colonial, and industrial intervals, Hg pollution became regional, as evidenced by a third lake record ≈225 km distant from Huancavelica. Measurements of sediment-Hg speciation reveal that cinnabar dust was initially the dominant Hg species deposited, and significant increases in deposition were limited to the local environment. After conquest by the Inca (ca. 1450 AD), smelting was adopted at the mine and Hg pollution became more widely circulated, with the deposition of matrix-bound phases of Hg predominating over cinnabar dust. Our results demonstrate the existence of a major Hg mining industry at Huancavelica spanning the past 3,500 years, and place recent Hg enrichment in the Andes in a broader historical context. PMID:19451629

  9. Characteristics of Precipitation Features and Annual Rainfall during the TRMM Era in the Central Andes

    NASA Technical Reports Server (NTRS)

    Mohr, Karen I.; Slayback, Daniel; Yager, Karina

    2014-01-01

    The central Andes extends from 7 deg to 21 deg S, with its eastern boundary defined by elevation (1000m and greater) and its western boundary by the coastline. The authors used a combination of surface observations, reanalysis, and the University of Utah Tropical Rainfall Measuring Mission (TRMM) precipitation features (PF) database to understand the characteristics of convective systems and associated rainfall in the central Andes during the TRMM era, 1998-2012. Compared to other dry (West Africa), mountainous (Himalayas), and dynamically linked (Amazon) regions in the tropics, the central Andes PF population was distinct from these other regions, with small and weak PFs dominating its cumulative distribution functions and annual rainfall totals. No more than 10% of PFs in the central Andes met any of the thresholds used to identify and define deep convection (minimum IR cloud-top temperatures, minimum 85-GHz brightness temperature, maximum height of the 40-dBZ echo). For most of the PFs, available moisture was limited (less than 35mm) and instability low (less than 500 J kg(exp -1)). The central Andes represents a largely stable, dry to arid environment, limiting system development and organization. Hence, primarily short-duration events (less than 60 min) characterized by shallow convection and light to light-moderate rainfall rates (0.5-4.0 mm h(exp -1)) were found.

  10. 15. INTERIOR, NORTHWESTERN WING, SHOW ROOM, DETAIL OF BALCONY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. INTERIOR, NORTHWESTERN WING, SHOW ROOM, DETAIL OF BALCONY - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  11. 14. INTERIOR, NORTHWESTERN WING, SHOW ROOM, DETAIL OF FIREPLACE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. INTERIOR, NORTHWESTERN WING, SHOW ROOM, DETAIL OF FIREPLACE - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  12. Northeastern Exterior, Northwestern Exterior, & Southwestern Exterior Elevations, Northeastern Interior, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Northeastern Exterior, Northwestern Exterior, & Southwestern Exterior Elevations, Northeastern Interior, Southeastern Interior, & Southwestern Interior Elevations, Floor Plan, and Eastern Corner Detail - Manatoc Reservation, Vale Edge Adirondack, 1075 Truxell Road, Peninsula, Summit County, OH

  13. Structure and tectonic evolution of the Fuegian Andes (southernmost South America) in the framework of the Scotia Arc development

    NASA Astrophysics Data System (ADS)

    Torres Carbonell, Pablo J.; Dimieri, Luis V.; Olivero, Eduardo B.; Bohoyo, Fernando; Galindo-Zaldívar, Jesús

    2014-12-01

    The major structural and tectonic features of the Fuegian Andes provide an outstanding onshore geological framework that aids in the understanding of the tectonic evolution of the Scotia Arc, mainly known from offshore studies. The orogenic history of the Fuegian Andes (Late Cretaceous-Miocene) is thus compared and integrated with the tectonic history of the Scotia Sea. Late Cretaceous-Paleocene structures in the Fuegian Andes suggest a N-directed contraction consistent with an oroclinal bending of the southernmost South America-Antarctic Peninsula continental bridge. This N-directed contraction in the Fuegian Andes continued during the spreading of the West Scotia Ridge, between 40-50 and 10 Ma ago. The onset of major strike-slip faulting in Tierra del Fuego is considered here to be not older than the late Miocene, consistent with the recent history of the North Scotia Ridge; thus forming part of a tectonic regime superposed to the prior contraction in the Fuegian Andes.

  14. Central Andes mountains, Chile/Argentina as seen from STS-67

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Chilean coastline and the arid Atacama Desert stretch the length of the view with the high Andes on the eastern margin where hundreds of volcanoes dot the landscape. The wider (250-350 kilometers) Altiplano ('plains') sector of the Andes appears in the top half of the view, and the narrow (120 kilometers) 'mountain-chain-dominated' sector to the bottom. The northern half of Chile can be seen, with the 'hammer-head' peninsula at the city of Antofagasta, top left. Up welling of cold water as the Humboldt Current immediately offshore gives rise to low stratus cloud. The extensive cloud mass on the right lies beyond the Andes in the low country of Argentina's 'pampas' grasslands and Chaco semi-desert.

  15. The First Ten Months of Investigation of Gravity Waves and Temperature Variability Over the Andes

    NASA Astrophysics Data System (ADS)

    Pugmire, Jonathan; Criddle, Neal; Taylor, Michael; Pautet, Dominique; Zhao, Yucheng

    2010-10-01

    The Andes region is an excellent natural laboratory for investigating gravity wave influences on the Upper Mesospheric and Lower Thermospheric (MLT) dynamics. The instrument suite that comprised the very successful Maui-MALT program was recently re-located to a new Andes Lidar Observatory (ALO) located at Cerro Pachon, Chile to obtain in-depth seasonal measurements of MLT dynamics over the Andes mountains. As part of the instrument set the Utah State University CEDAR Mesospheric Temperature Mapper (MTM) has operated continuously since August 2009 measuring the near infrared OH(6,2) band and the O2(0,1) Atmospheric band intensity and temperature perturbations. This poster focuses on an analysis of nightly OH temperatures and the observed variability, as well as selected gravity wave events illustrating the high wave activity and its diversity.

  16. Traditional use of the Andean flicker (Colaptes rupicola) as a galactagogue in the Peruvian Andes

    PubMed Central

    Froemming, Steve

    2006-01-01

    This paper explores the use of the dried meat and feathers of the Andean Flicker (Colaptes rupicola) to increase the milk supply of nursing women and domestic animals in the Andes. The treatment is of preColumbian origin, but continues to be used in some areas, including the village in the southern Peruvian highlands where I do ethnographic research. I explore the factors giving rise to and sustaining the practice, relate it to other galactagogues used in the Andes and to the use of birds in ethnomedical and ethnoveterinary treatments in general, and situate it within the general tendency in the Andes and elsewhere to replicate human relations in the treatment of valuable livestock. The bird's use as a galactagogue appears to be motivated by both metaphorical associations and its perceived efficacy, and conceptually blends human and animal healthcare domains. PMID:16677398

  17. STS-65 Earth observation of Northern Chile and Andes Mtns taken from OV-102

    NASA Technical Reports Server (NTRS)

    1994-01-01

    STS-65 Earth observation taken aboard Columbia, Orbiter Vehicle (OV) 102, shows Northern Chile and the Andes Mountains. This color photograph is a panoramic (southern view) that features Chile and the Andes Mountains of South America. The Atacama Desert, one of the driest regions on Earth, is clearly visible along the Chilean coast. In the near left foreground is the Salar de Arizaro. Salar Punta Negra in the center foreground appears to be partially filled with water. On the right side of the view, a coastal plateau rises from the Pacific Ocean and meets the Andes Mountains that appear as a backbone running north to south along the border of Chile and Argentina. In the distant left portion of the view can be seen the hazy Chaco Plains and Pampas.

  18. A rare case of Kearns–Sayre syndrome in a 17-year-old Venezuelan male with bilateral ptosis as the initial presentation

    PubMed Central

    Leal, Mayela; Dhoble, Chetan; Lee, Julie; Lopez, Deinymar; Menéndez, Laura Simonne

    2016-01-01

    Kearns–Sayre syndrome (KSS) was first described in 1958 as ‘a rare neuromuscular disorder defined by a characteristic triad of progressive external ophthalmoplegia, pigmentary retinopathy, atrioventricular block and cerebellar ataxia’. The prevalence rate of KSS is ∼1–3 per 100 000 individuals. Here, we report a rare case of a 17-year-old Venezuelan male with KSS. PMID:26949540

  19. Possible future lakes in the Andes of Peru

    NASA Astrophysics Data System (ADS)

    Colonia, Daniel; Haeberli, Wilfried; Torres, Judith; Giraldez, Claudia; Schauwecker, Simone; Santiago, Alexzander; Cochachin, Alejo; Huggel, Christian

    2015-04-01

    Climate change has caused large losses of glacier mass in the Andes of Peru. Also, given the projected changes in climate, based on different IPCC scenarios for 2050 and 2080, simulations with a tropical glacier-climate model indicate that glaciers will continue to retreat. According to the national Peruvian glacier inventories 43% of glacier area has disappeared between 1970 and 2003-2010 in the 19 snowy mountain ranges and a total of 8 355 new lakes have formed in deglaciating terrain. With glacier retreat new lakes form in parts of the glacier tongue where there is an overdeepening, and these lakes can be a source of natural hazards to downstrean populations. Therefore, the identification of possible future lakes is important to plan for preventive measures concerning possible lake outbursts as well as to understand changes in freshwater storage in the corresponding source areas. Modeling of glacier-bed overdeepenings and possible future lakes forming in such topographic depressions when becoming ice-free was done using the SRTM DEM from the year 2000 with a 90 m resolution and the 2003-2010 glacier outlines from the recently published national glacier inventory of Perú. The GIS-based analysis followed three main steps: (1) identification of flat glacier areas with less than 10° surface slope as a first-order spatial approximation to possible occurrences of glacier-bed overdeepenings; (2) application, using Google Earth, of three morphological indications of glacier-bed overdeepenings following Frey et al. (2010): steepening surface slope, onset of crevasse formation, lateral flow-narrowing; and (3) verification of the results from steps (1) and (2) by comparison with GlabTop modeling of bed topographies following Linsbauer et al. (2012) using the SRTM DEM, contour lines and constructed branch lines for all glaciers. A pilot study has already been carried out for the Cordillera Blanca. The results show that 31 major new lakes may form in the future. The total

  20. Carbon stabilization mechanisms in soils in the Andes

    NASA Astrophysics Data System (ADS)

    Jansen, Boris; Cammeraat, Erik

    2015-04-01

    The volcanic ash soils of the Andes contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute significant potential sources or sinks of the greenhouse gas CO2. Climate and/or land use change potentially have a strong effect on these large SOM stocks. To clarify the role of chemical and physical stabilisation mechanisms in volcanic ash soils in the montane tropics, we investigated carbon stocks and stabilization mechanisms in the top- and subsoil along an altitudinal transect in the Ecuadorian Andes. The transect encompassed a sequence of paleosols under forest and grassland (páramo), including a site where vegetation cover changed in the last century. We applied selective extraction techniques, performed X-ray diffraction analyses of the clay fraction and estimated pore size distributions at various depths in the top- and subsoil along the transect. In addition, from several soils the molecular composition of SOM was further characterized with depth in the current soil as well as the entire first and the top of the second paleosol using GC/MS analyses of extractable lipids and Pyrolysis-GC/MS analyses of bulk organic matter. Our results show that organic carbon stocks in the mineral soil under forest a páramo vegetation were roughly twice as large as global averages for volcanic ash soils, regardless of whether the first 30cm, 100cm or 200cm were considered. We found the carbon stabilization mechanisms involved to be: i) direct stabilization of SOM in organo-metallic (Al-OM) complexes; ii) indirect protection of SOM through low soil pH and toxic levels of Al; and iii) physical protection of SOM due to a very high microporosity of the soil (Tonneijck et al., 2010; Jansen et al. 2011). When examining the organic carbon at a molecular level, interestingly we found extensive degradation of lignin in the topsoil while extractable lipids were preferentially preserved in the subsoil (Nierop and Jansen, 2009). Both vegetation

  1. Two New Species of Black Flies (Diptera: Simuliidae) from the High Andes of Colombia.

    PubMed

    Mantilla, Juan S; Moncada, Ligia I; Matta, Nubia E; Adler, Peter H

    2013-01-01

    The females, males, pupae, and larvae of two new species of Simulium are described and illustrated from a small stream 3950 m above sea level in the Lake Otún area of the Colombian Andes Mountains. Simulium (Pternaspatha) quimbayium n. sp. represents a 630-km northeastern extension of the distributional range of previously known members of the subgenus Pternaspatha, and Simulium (Psilopelmia) machetorum n. sp. represents the highest altitude recorded for a species of the subgenus Psilopelmia. These species illustrate the unique simuliid biodiversity in the páramo ecosystem of the high northern Andes.

  2. Bayesian spatiotemporal interpolation of rainfall in the Central Chilean Andes

    NASA Astrophysics Data System (ADS)

    Ossa-Moreno, Juan; Keir, Greg; McIntyre, Neil

    2016-04-01

    Water availability in the populous and economically significant Central Chilean region is governed by complex interactions between precipitation, temperature, snow and glacier melt, and streamflow. Streamflow prediction at daily time scales depends strongly on accurate estimations of precipitation in this predominantly dry region, particularly during the winter period. This can be difficult as gauged rainfall records are scarce, especially in the higher elevation regions of the Chilean Andes, and topographic influences on rainfall are not well understood. Remotely sensed precipitation and topographic products can be used to construct spatiotemporal multivariate regression models to estimate rainfall at ungauged locations. However, classical estimation methods such as kriging cannot easily accommodate the complicated statistical features of the data, including many 'no rainfall' observations, as well as non-normality, non-stationarity, and temporal autocorrelation. We use a separable space-time model to predict rainfall using the R-INLA package for computationally efficient Bayesian inference, using the gridded CHIRPS satellite-based rainfall dataset and digital elevation models as covariates. We jointly model both the probability of rainfall occurrence on a given day (using a binomial likelihood) as well as amount (using a gamma likelihood or similar). Correlation in space and time is modelled using a Gaussian Markov Random Field (GMRF) with a Matérn spatial covariance function which can evolve over time according to an autoregressive model if desired. It is possible to evaluate the GMRF at relatively coarse temporal resolution to speed up computations, but still produce daily rainfall predictions. We describe the process of model selection and inference using an information criterion approach, which we use to objectively select from competing models with various combinations of temporal smoothing, likelihoods, and autoregressive model orders.

  3. Erosion by Ice and Water in the Southern Andes

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This scene on the remote, rugged Argentine/Chilean border in the far southern Andes Mountains offers numerous, dramatic examples of both erosional processes and features of ice and water. The sharp, glaciated crest of the Cerro San Lorenzo (center) exceeds 12,000 feet and casts a long shadow southeastward. Glaciers on its western flank flow into the valley. This Electronic Still Camera photo was taken from the International Space Station, in December 2000 (late spring) when most of the previous winter's snow had melted below an altitude of 6,000 feet. Lago Pueyrredon, and the other lakes visible here, have been excavated by geologically recent episodes of glacier erosion, when glaciers extended all the way onto the lowland plains (top right). Since the last melting of the glaciers (15,000 years ago) three distinct fan deltas (semicircular features, marked with arrows) have formed where rivers flow into the lake. Counterclockwise currents in the lake-driven by strong winds from the west-have generated thin sand spits from each fan-delta. The largest spit (attached to the largest fan-delta, see right arrow) has isolated an approximately 10-kilometer long segment of the south end of the lake. The river that constructed the largest fan presently discharges turbid water to this isolated basin, giving it a lighter color than the rest of the lake. Glacial data collected over the past 50 years indicate that small ice bodies are disappearing at accelerated rates. (EOS, vol 81, no. 24, June 13, 2000) Predictions are that large fluctuations in land ice, with significant implications to society, are possible in the coming decades and centuries due to natural and anthropogenic climate change. Before glacial data can be used to address critical problems pertaining to the world's economic and environmental health, more detailed information about such glaciers is needed. Image ISS001-ESC-5113 provided by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center.

  4. Cenozoic building and deformational processes in the North Patagonian Andes

    NASA Astrophysics Data System (ADS)

    Orts, Darío L.; Folguera, Andrés; Giménez, Mario; Ruiz, Francisco; Rojas Vera, Emilio A.; Lince Klinger, Federico

    2015-05-01

    The Oligocene to present evolution of the North Patagonian Andes is analyzed linking geological and geophysical data in order to decipher the deformational processes that acted through time and relate them to basin formation processes. Seismic reflection profiles reveal the shallow structure of the retroarc area where contractional structures, associated with Oligocene to early Miocene inverted extensional depocenters, are partially onlapped by early to late Miocene synorogenic deposits. From the construction of five structural cross sections along the retroarc area between 40° and 43°30‧ S, constrained by surface, gravity and seismic data, a shortening gradient is observed along Andean strike. The highest shortening of 18.7 km (15.34%) is determined near 41°30‧ S coincidentally with maximum mean topographic values on the eastern Andean slope, where basement blocks were uplifted in the orogenic front area, and the deepest and broadest synorogenic depocenters were formed towards the foreland. Additionally, eastward shifting of Miocene calc-alkaline rocks occurred at these latitudes, which is interpreted as indicative of a change in the subduction parameters at this time. Deep crustal retroarc structure is evaluated through inversion of gravity models that made possible to infer Moho attenuated zones. These coincide with the occurrence of younger than 5 Ma within-plate volcanics as well as with crustal thermal anomalies suggested by shallowing of the Curie isotherm calculated from magnetic data. Younger volcanism and thermal anomalies are explained by slab steepening since early Pliocene, after a mild-shallow subduction setting in the middle to late Miocene, age of the main compressive event.

  5. Glacier loss and emerging hydrologic vulnerabilities in the Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Mark, B. G.; McKenzie, J. M.; Baraer, M.; Lagos, P.; Lautz, L.; Carey, M.; Bury, J.; Crumley, R.; Wigmore, O.; Somers, L. D.

    2015-12-01

    Accelerating glacier recession in the tropical Andes is transforming downstream hydrology, while increasing demands for water by end-users (even beyond the watershed limits) is complicating the assessment of vulnerability. Future scenarios of hydro-climatic vulnerability require a better understanding of coupled hydrologic and human systems, involving both multiscale process studies and more robust models of glacier-climate interactions. We synthesize research in two proglacial valleys of glacierized mountain ranges in different regions of Peru that are both in proximity to growing water usage from urban sectors, agriculture, hydroelectric generation, and mining. In both the Santa River watershed draining the Cordillera Blanca and the Shullcas River watershed below Hyuatapallana Mountain in Junin, glaciers have receded over 25% since the 1980s. Historical runoff and glacier data, combined with glacier-climate modeling, show a long-term decrease in discharge resulting from a net loss of stored water. We find evidence that this altered hydrology is transforming proglacial wetland ecology and water quality, even while water resource use has intensified. Beyond glaciers, our results show that over 60% of the dry season base flow in each watershed is groundwater sourced from heterogeneous aquifers. Municipal water supply in Huancayo already relies on 18 groundwater wells. Perceptions of water availability and actual water use practices remain relatively divorced from the actual water resources provided from each mountain range. Critical changes in glacier volume and water supply are not perceived or acknowledged consistently amongst different water users, nor reflected in water management decisions. In order to identify, understand, model, and adapt to climate-glacier-water changes, it is vital to integrate the analysis of water availability and groundwater processes (the domain of hydrologists) with that of water use (the focus for social scientists). Attention must be

  6. The nature of orogenic crust in the central Andes

    NASA Astrophysics Data System (ADS)

    Beck, Susan L.; Zandt, George

    2002-10-01

    The central Andes (16°-22°S) are part of an active continental margin mountain belt and the result of shortening of the weak western edge of South America between the strong lithospheres of the subducting Nazca plate and the underthrusting Brazilian shield. We have combined receiver function and surface wave dispersion results from the BANJO-SEDA project with other geophysical studies to characterize the nature of the continental crust and mantle lithospheric structure. The major results are as follows: (1) The crust supporting the high elevations is thick and has a felsic to intermediate bulk composition. (2) The relatively strong Brazilian lithosphere is underthrusting as far west (65.5°W) as the high elevations of the western part of the Eastern Cordillera (EC) but does not underthrust the entire Altiplano. (3) The subcrustal lithosphere is delaminating piecemeal under the Altiplano-EC boundary but is not completely removed beneath the central Altiplano. The Altiplano crust is characterized by a brittle upper crust decoupled from a very weak lower crust that is dominated by ductile deformation, leading to lower crustal flow and flat topography. In contrast, in the high-relief, inland-sloping regions of the EC and sub-Andean zone, the upper crust is still strongly coupled across the basal thrust of the fold-thrust belt to the underthrusting Brazilian Shield lithosphere. Subcrustal shortening between the Altiplano and Brazilian lithosphere appears to be accommodated by delamination near the Altiplano-EC boundary. Our study suggests that orogenic reworking may be an important part of the "felsification" of continental crust.

  7. Glaciological studies in the central Andes using AIRSAR/TOPSAR

    NASA Technical Reports Server (NTRS)

    Forster, Richard R.; Klein, Andrew G.; Blodgett, Troy A.; Isacks, Bryan L.

    1993-01-01

    The interaction of climate and topography in mountainous regions is dramatically expressed in the spatial distribution of glaciers and snowcover. Monitoring existing alpine glaciers and snow extent provides insight into the present mountain climate system and how it is changing, while mapping the positions of former glaciers as recorded in landforms such as cirques and moraines provide a record of the large past climate change associated with the last glacial maximum. The Andes are an ideal mountain range in which to study the response of snow and ice to past and present climate change. Their expansive latitudinal extent offers the opportunity to study glaciers in diverse climate settings from the tropical glaciers of Peru and Bolivia to the ice caps and tide-water glaciers of sub-polar Patagonia. SAR has advantages over traditional passive remote sensing instruments for monitoring present snow and ice and differentiating moraine relative ages. The cloud penetrating ability of SAR is indispensable for perennially cloud covered mountains. Snow and ice facies can be distinguished from SAR's response to surface roughness, liquid water content and grain size distribution. The combination of SAR with a coregestered high-resolution DEM (TOPSAR) provides a promising tool for measuring glacier change in three dimensions, thus allowing ice volume change to be measured directly. The change in moraine surface roughness over time enables SAR to differentiate older from younger moraines. Polarimetric SAR data have been used to distinguish snow and ice facies and relatively date moraines. However, both algorithms are still experimental and require ground truth verification. We plan to extend the SAR classification of snow and ice facies and moraine age beyond the ground truth sites to throughout the Cordillera Real to provide a regional view of past and present snow and ice. The high resolution DEM will enhance the SAR moraine dating technique by discriminating relative ages

  8. High resolution precipitation climatology for the Andes of South Ecuador

    NASA Astrophysics Data System (ADS)

    Trachte, Katja; Bendix, Jörg

    2014-05-01

    The climate of Ecuador is strongly dominated by the complex structure of the Andes Mountains. Due to their heights and north-south orientation they act like a barrier, which cause delineation between the western and eastern flanks, as well as the inner-Andean areas. Commonly the Ecuadorian climate is classified in three zones, Costa, Interandina and Oriente. Existing precipitation products such as the GPCC or TRMM data are enabled to represent these climate zones, but because of their spatial resolution, they pass to capture the different regimes within a zone. Especially the inner-Andean region (Interandina) with its characteristic complex terrain shows spatially high climate variability. Local circulation systems, e.g. mountain-valley breezes as well as effects of windward and lee-side, drive the climate conditions allowing for the differentiation of air temperature and rainfall distribution on relative small scales. These highly variable patterns are also reflected by the diversity of ecosystems, e.g. rainforest, dry forest and Paramo, in a relative small area. In order to represent the local systems a dynamical downscaling approach for the Ecuadorian region is applied. In doing so the Weather Research and Forecasting (WRF) model is used. A suitable model setup was evaluated within a sensitivity study, where various parametrization schemes were tested. The most suitable physics combination was used for a 30 year hint cast simulation. The poster presents first results of the high resolution climate simulations. On the basis of the spatial distribution of rainfall patterns distinct precipitation regimes within the Interandina will be shown. The aim is to highlight and discuss the importance of the adequately representation of the terrain in mountainous regions like the Andean Mountains.

  9. Host mTORC1 Signaling Regulates Andes Virus Replication

    PubMed Central

    McNulty, Shannon; Flint, Mike; Nichol, Stuart T.

    2013-01-01

    Hantavirus pulmonary syndrome (HPS) is a severe respiratory disease characterized by pulmonary edema, with fatality rates of 35 to 45%. Disease occurs following infection with pathogenic New World hantaviruses, such as Andes virus (ANDV), which targets lung microvascular endothelial cells. During replication, the virus scavenges 5′-m7G caps from cellular mRNA to ensure efficient translation of viral proteins by the host cell cap-dependent translation machinery. In cells, the mammalian target of rapamycin (mTOR) regulates the activity of host cap-dependent translation by integrating amino acid, energy, and oxygen availability signals. Since there is no approved pharmacological treatment for HPS, we investigated whether inhibitors of the mTOR pathway could reduce hantavirus infection. Here, we demonstrate that treatment with the FDA-approved rapamycin analogue temsirolimus (CCI-779) blocks ANDV protein expression and virion release but not entry into primary human microvascular endothelial cells. This effect was specific to viral proteins, as temsirolimus treatment did not block host protein synthesis. We confirmed that temsirolimus targeted host mTOR complex 1 (mTORC1) and not a viral protein, as knockdown of mTORC1 and mTORC1 activators but not mTOR complex 2 components reduced ANDV replication. Additionally, primary fibroblasts from a patient with tuberous sclerosis exhibited increased mTORC1 activity and increased ANDV protein expression, which were blocked following temsirolimus treatment. Finally, we show that ANDV glycoprotein Gn colocalized with mTOR and lysosomes in infected cells. Together, these data demonstrate that mTORC1 signaling regulates ANDV replication and suggest that the hantavirus Gn protein may modulate mTOR and lysosomal signaling during infection, thus bypassing the cellular regulation of translation. PMID:23135723

  10. Morphologic evolution of the Central Andes of Peru

    NASA Astrophysics Data System (ADS)

    Gonzalez, Laura; Pfiffner, O. Adrian

    2012-01-01

    In this paper, we analyze the morphology of the Andes of Peru and its evolution based on the geometry of river channels, their bedrock profiles, stream gradient indices and the relation between thrust faults and morphology. The rivers of the Pacific Basin incised Mesozoic sediments of the Marañon thrust belt, Cenozoic volcanics and the granitic rocks of the Coastal Batholith. They are mainly bedrock channels with convex upward shapes and show signs of active ongoing incision. The changes in lithology do not correlate with breaks in slope of the channels (or knick points) such that the high gradient indices (K) with values between 2,000-3,000 and higher than 3,000 suggest that incision is controlled by tectonic activity. Our analysis reveals that many of the ranges of the Western Cordillera were uplifted to the actual elevations where peaks reach to 6,000 m above sea level by thrusting along steeply dipping faults. We correlate this uplift with the Quechua Phase of Neogene age documented for the Subandean thrust belt. The rivers of the Amazonas Basin have steep slopes and high gradient indices of 2,000-3,000 and locally more than 3,000 in those segments where the rivers flow over the crystalline basement of the Eastern Cordillera affected by vertical faulting. Gradient indices decrease to 1,000-2,000 within the east-vergent thrust belt of the Subandean Zone. Here a correlation between breaks in river channel slopes and location of thrust faults can be established, suggesting that the young, Quechua Phase thrust faults of the Subandean thrust belt, which involve Neogene sediments, influenced the channel geometry. In the eastern lowlands, these rivers become meandering and flow parallel to anticlines that formed in the hanging wall of Quechua Phase thrust faults, suggesting that the river courses were actively displaced outward into the foreland.

  11. Northwestern Tharsis Latent Outflow Activity Mars

    NASA Technical Reports Server (NTRS)

    Dohm, J. M.; Anderson, R. C.; Baker, V. R.; Ferris, J. C.; Hare, T. M.; Strom, R. G.; Rudd, L.; Rice, J. W., Jr.; Scott, D. H.

    2000-01-01

    Previously defined outflow channels, which are indicated by relict landforms similar to those observed on Earth, signify ancient catastrophic flood events on Mars. These conspicuous geomorphic features are some of the most remarkable yet profound discoveries made by geologists to date. These outflow channels, which debouched tremendous volumes of water into topographic lows such as Chryse, Utopia, Elysium, and Hellas Planitiae, may represent the beginning of warmer and wetter climatic periods unlike the present-day cold and dry Mars. In addition to the previously identified outflow channels, observations permitted by the newly acquired Mars Orbiter Laser Altimeter (MOLA) data have revealed a system of gigantic valleys, referred to as the northwestern slope valleys (NSV), that are located to the northwest of a huge shield volcano, Arsia Mons, western hemisphere of Mars. These features generally correspond spatially to gravity lows similar to the easternmost, circum-Chryse outflow channel systems. Geologic investigations of the Tharsis region suggest that the large valley system pre-dates the construction of Arsia Mons and its extensive associated lava flows of mainly Late Hesperian and Amazonian age and coincides stratigraphically with the early development of the circum-Chryse outflow channel systems that debouch into Chryse Planitia. This newly identified system, the NSV, potentially signifies the largest flood event(s) ever recorded for the solar system. Additional information is contained in original extended abstract.

  12. MISR Images Wildfires in Northwestern US

    NASA Technical Reports Server (NTRS)

    2000-01-01

    MISR image of smoke plumes from devastating wildfires in the northwestern US. This view of the Clearwater and Salmon River Mountains in Idaho was acquired on August 5, 2000 (Terra orbit 3370). The body of water to the left of image center is the Cascade Reservoir, located about 100 km north of Boise and 80 km east of the Snake River. North is at the top, and the image is approximately 380 km across.

    In addition to the huge plumes traversing the mountains in the northern part of the image, smoke accumulating in the lower elevation canyons and plains is visible. This image was generated using data from the MISR camera that looks forward at a steep angle (70.5 degrees). The smoke is far more visible when viewed at this highly oblique angle than it would be in a conventional, straight-downward view. In creating this color composite, data from the blue and green MISR bands, acquired at 1.1-km spatial resolution, were digitally 'sharpened' using 275-m resolution data acquired in the red band.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

    For more information: http://www-misr.jpl.nasa.gov

  13. Lineament analysis near French Creek, northwestern Pennsylvania

    SciTech Connect

    O'Neil, C.; Anderson, T.

    1984-12-01

    The authors are attempting to characterize the nature of linear topographic features in the vicinity of French Creek, northwestern Pennsylvania. Straight valleys that trend north to northwest and that are partially filled with glaciofluvial deposits distinguish prominent lineaments in Crawford, Venango, and Mercer Counties. The traces of these linear valleys are 1-15 mi (1.6-24 km) long and 10-4000 ft (3-1220 m) wide. The vertical extents of the lineaments are assumed to be proportional to their lengths. They assume that the topographic lineaments mark easily eroded zones coincident with fractures. The French Creek lineaments have been plotted on a Landsat photo, glacial map, regional map, and topographic maps. Subsurface structural and isopach maps may show facies changes or anomalous thickness across the lineaments. Geochemical surveys determine if there is any enhanced vertical migration of hydrocarbons along a lineament, and very low-frequency magnetic surveys would indicate any increase in groundwater concentration associated with the fracture zones. Well log data on initial production and breakdown pressures have been compared to lineament positions for possible correlations.

  14. Discrimination of Venezuelan spirituous beverages by a trace element-radial basis neural network approach.

    PubMed

    Hernández-Caraballo, Edwin A; Avila de Hernández, Rita M; Rivas-Echeverría, Francklin; Capote-Luna, Tarcisio

    2008-01-15

    Radial basis neural networks (RBNNs) were developed and evaluated for discrimination of specimens of 'aguardiente de Cocuy', a spirituous beverage produced in the northwestern region of Venezuela. The beverage is distilled from the must of Agave cocui Trelease in an artisanship fashion with little quality control. Forty specimens, with known concentrations of copper, iron, and zinc, were used in this study. The specimens were previously collected in various locations around Sucre Municipality (Falcón State) and Urdaneta Municipality (Lara State). The normalized concentrations of these elements served as indirect descriptors of origin (input data). They were presented to the neural networks through 1-3 input nodes in seven different combinations. In addition, two categories (two collection sites) and four categories (two collection sites+two manufacturing conditions) were designated as output data, in order to assess the impact of such selection on the discrimination performance. The overall performance of the four-category RBNNs was as follows (the input data is indicated in parentheses): (Cu-Fe)>(Cu-Zn)>(Cu)>(Zn)>(Fe-Zn)>(Cu-Fe-Zn)>(Fe). In this case, the highest percentage of correct hits was 82.5%. For the two-category RBNNs, the performance decreased as indicated below: (Cu)>(Cu-Fe)>(Cu-Zn)>(Fe-Zn)>(Zn) approximately (Cu-Fe-Zn)>(Fe). The reduction in the number of categories led to an increase in the discrimination performance of all the RBNNs, the best of which was 90.0%. The possibility of discriminating specimens of 'aguardiente de Cocuy' with such an accuracy, based on a single-element determination, is particularly attractive as it would result in a reduction of analysis' costs and laboratory's response time.

  15. Discrimination of Venezuelan spirituous beverages by a trace element-radial basis neural network approach.

    PubMed

    Hernández-Caraballo, Edwin A; Avila de Hernández, Rita M; Rivas-Echeverría, Francklin; Capote-Luna, Tarcisio

    2008-01-15

    Radial basis neural networks (RBNNs) were developed and evaluated for discrimination of specimens of 'aguardiente de Cocuy', a spirituous beverage produced in the northwestern region of Venezuela. The beverage is distilled from the must of Agave cocui Trelease in an artisanship fashion with little quality control. Forty specimens, with known concentrations of copper, iron, and zinc, were used in this study. The specimens were previously collected in various locations around Sucre Municipality (Falcón State) and Urdaneta Municipality (Lara State). The normalized concentrations of these elements served as indirect descriptors of origin (input data). They were presented to the neural networks through 1-3 input nodes in seven different combinations. In addition, two categories (two collection sites) and four categories (two collection sites+two manufacturing conditions) were designated as output data, in order to assess the impact of such selection on the discrimination performance. The overall performance of the four-category RBNNs was as follows (the input data is indicated in parentheses): (Cu-Fe)>(Cu-Zn)>(Cu)>(Zn)>(Fe-Zn)>(Cu-Fe-Zn)>(Fe). In this case, the highest percentage of correct hits was 82.5%. For the two-category RBNNs, the performance decreased as indicated below: (Cu)>(Cu-Fe)>(Cu-Zn)>(Fe-Zn)>(Zn) approximately (Cu-Fe-Zn)>(Fe). The reduction in the number of categories led to an increase in the discrimination performance of all the RBNNs, the best of which was 90.0%. The possibility of discriminating specimens of 'aguardiente de Cocuy' with such an accuracy, based on a single-element determination, is particularly attractive as it would result in a reduction of analysis' costs and laboratory's response time. PMID:18371722

  16. Jurassic platform development, northwestern Gulf of Mexico

    SciTech Connect

    Moore, C.H. Jr.

    1987-05-01

    Triassic and Early Jurassic rifting set the stage for the subsequent development of carbonate platforms in the Late Jurassic. These platforms formed along the interior margins of salt basins separated from the main ancestral Gulf of Mexico by a series of positive features. A major sea level rise, after deposition of the Louann Salt (late Callovian), drowned the interior salt basins around the margins of the Gulf of Mexico, leading to an anoxic event. Organic-rich sediments of the lower Smackover were deposited as a basin-fill sequence, forming one of the major hydrocarbon source rocks of the region. As sea level rise slowed in the late Oxfordian, carbonate production began to catch up with sea level rise along the basin margins, leading to the initial development of a rimmed carbonate platform. The platform margin was marked by high-energy ooid grainstones, while crustacean pellet muds were deposited in the platform interior. A high-energy ooid-dominated platform (upper Smackover) developed in the late Oxfordian when sea level reached a standstill. During the subsequent Kimmeridgian sea level rise, a second rimmed carbonate platform, the Haynesville, was developed. During the initial rise, grainstones were deposited on the platform margin, while the interior was dominated by evaporites (Buckner) and siliciclastics. As sea level slowed and reached a standstill, the platform margin facies extended shoreward (Gilmer) and a high-energy platform, analogous to the upper Smackover, was formed. The Smackover and Haynesville platforms of the northwestern gulf show a parallel evolution in response to cyclic changes in Upper Jurassic sea level.

  17. Stepwise colonization of the Andes by ruddy ducks and the evolution of novel β-globin variants.

    PubMed

    Muñoz-Fuentes, V; Cortázar-Chinarro, M; Lozano-Jaramillo, M; McCracken, K G

    2013-03-01

    Andean uplift played a key role in Neotropical bird diversification, yet past dispersal and genetic adaptation to high-altitude environments remain little understood. Here we use multilocus population genetics to study population history and historical demographic processes in the ruddy duck (Oxyura jamaicensis), a stiff-tailed diving duck comprising three subspecies distributed from Canada to Tierra del Fuego and inhabiting wetlands from sea level to 4500 m in the Andes. We sequenced the mitochondrial DNA, four autosomal introns and three haemoglobin genes (α(A), α(D), β(A)) and used isolation-with-migration (IM) models to study gene flow between North America and South America, and between the tropical and southern Andes. Our analyses indicated that ruddy ducks dispersed first from North America to the tropical Andes, then from the tropical Andes to the southern Andes. While no nonsynonymous substitutions were found in either α globin gene, three amino acid substitutions were observed in the β(A) globin. Based on phylogenetic reconstruction and power analysis, the first β(A) substitution, found in all Andean individuals, was acquired when ruddy ducks dispersed from low altitude in North America to high altitude in the tropical Andes, whereas the two additional substitutions occurred more recently, when ruddy ducks dispersed from high altitude in the tropical Andes to low altitude in the southern Andes. This stepwise colonization pattern accompanied by polarized β(A) globin amino acid replacements suggest that ruddy ducks first acclimatized or adapted to the Andean highlands and then again to the lowlands. In addition, ruddy ducks colonized the Andean highlands via a less common route as compared to other waterbird species that colonized the Andes northwards from the southern cone of South America. PMID:23346994

  18. Hybrid Literacies: The Case of a Quechua Community in the Andes

    ERIC Educational Resources Information Center

    de la Piedra, Maria Teresa

    2009-01-01

    Drawing on data from an ethnographic study in a Quechua rural community in the Peruvian Andes, this article examines hybrid literacy practices among bilingual rural speakers in the context of the household and the community. I examine the coexistence of two types of textual practices that operate side by side, at times integrated in the same…

  19. Deformation, deposition, and surface uplift in the hinterland of the Central Andes, Bolivia

    NASA Astrophysics Data System (ADS)

    Leier, A.; McQuarrie, N.; Garzione, C. N.; Eiler, J. M.

    2011-12-01

    Paleoelevation histories from mountain belts like the Central Andes of Bolivia provide important constraints on the timing and geodynamic mechanisms associated with surface uplift. New stable isotope data from paleosol carbonate nodules in the Altiplano and Eastern Cordillera of the Central Andes of Bolivia indicate a previously undocumented episode of surface uplift occurred in the region between ca. 24 and 17 Ma. Oxygen isotope and clumped-isotope thermometry values from paleosol carbonate in strata >24 Ma suggest paleoelevations as low as sea-level. Paleosol carbonate in strata ca. 17 Ma have oxygen isotope and clumped-isotope thermometry values, which using modern lapse rates, indicate an increase in elevation of approximately 3 km. Relatively undeformed Oligocene and Miocene strata overlap faulted Paleozoic rocks of the Bolivian Eastern Cordillera, indicating deposition and surface uplift post-dated and was decoupled from upper crustal deformation. Together, geological data from the area record an initial period of deformation and exhumation, a subsequent period of sediment deposition and overlap, and then an episode of surface uplift that was not accompanied by upper crustal deformation. We propose accommodation for the Oligocene-Miocene strata was associated with mantle and lowermost crustal processes, and the subsequent increase in surface elevation was an isostatic response to removal of dense material through delamination or drip. Combined with existing data sets in the Central Andes, these new data suggest multiple, regionally-variable, and diachronous periods of surface uplift occurred within the Central Andes during the Cenozoic Era.

  20. Lichenometric dating using Rhizocarpon subgenus Rhizocarpon in the Patagonian Andes, Argentina

    NASA Astrophysics Data System (ADS)

    Garibotti, Irene Adriana; Villalba, Ricardo

    2009-05-01

    This study represents the first attempt to develop and apply lichenometric dating curves of Rhizocarpon subgenus Rhizocarpon for dating glacier fluctuations in the Patagonian Andes. Six glaciers were studied along the Patagonian Andes. Surfaces of known ages (historical evidences and tree-ring analyses) were used as control sites to develop indirect lichenometric dating curves. Dating curves developed for the studied glaciers show the same general logarithmic form, indicating that growth rate of subgenus Rhizocarpon decreases over time. The strong west-east precipitation gradient across the Andean Cordillera introduces statistically significant differences in the growth curves, with faster growth rates in the moist west sites than the drier eastern sites. Latitudinal difference among the studied glaciers does not appear to be a major factor regulating lichen growth rates. Therefore, we developed two lichenometric curves for dating glacier fluctuations in wetter and drier sites in the Patagonian Andes during the past 450 yrs. Application of the developed curves to moraine dating allowed us to complement glacial chronologies previously obtained by tree-ring analyses. A first chronosequence for moraine formation in the Torrecillas Glacier (42°S) is presented. Our findings confirm the utility of lichenometry to date deglaciated surfaces in the Patagonian Andes.

  1. Knowledge and Learning in the Andes: Ethnographic Perspectives. Liverpool Latin American Studies, New Series 3.

    ERIC Educational Resources Information Center

    Stobart, Henry, Ed.; Howard, Rosaleen, Ed.

    This book presents research into the ways in which Indigenous peoples of the Andes create, transmit, maintain, and transform their knowledge, and the related processes of teaching and learning. Most chapters are based on papers delivered at a round-table conference at the University of Cambridge (England) in 1996 and include contributions from…

  2. "Nervios" and "Modern Childhood": Migration and Shifting Contexts of Child Life in the Ecuadorian Andes.

    ERIC Educational Resources Information Center

    Pribilsky, Jason

    2001-01-01

    Argues that beyond explanations predicated on psychological ideas of separation and attachment, "nervios," a depression-like disorder among children in the southern Ecuadorian Andes, reflects the limits of children's abilities to accept terms of family life increasingly defined through transnational migration and new consumption practices.…

  3. A millennium of metallurgy recorded by lake sediments from Morococha, Peruvian Andes.

    PubMed

    Cooke, Colin A; Abbott, Mark B; Wolfe, Alexander P; Kittleson, John L

    2007-05-15

    To date, information concerning pre-Colonial metallurgy in South America has largely been limited to the archaeological record of artifacts. Here, we reconstruct a millennium of smelting activity in the Peruvian Andes using the lake-sediment stratigraphy of atmospherically derived metals (Pb, Zn, Cu, Ag, Sb, Bi, and Ti) and lead isotopic ratios (206Pb/ 207Pb) associated with smelting from the Morococha mining region in the central Peruvian Andes. The earliest evidence for metallurgy occurs ca. 1000 A.D., coinciding with the fall of the Wari Empire and decentralization of local populations. Smelting during this interval appears to have been aimed at copper and copper alloys, because of large increases in Zn and Cu relative to Pb. A subsequent switch to silver metallurgy under Inca control (ca. 1450 to conquest, 1533 A.D.) is indicated by increases in Pb, Sb, and Bi, a conclusion supported by further increases of these metals during Colonial mining, which targeted silver extraction. Rapid development of the central Andes during the 20th century raised metal burdens by an order of magnitude above previous levels. Our results represent the first evidence for pre-Colonial smelting in the central Peruvian Andes, and corroborate the sensitivity of lake sediments to pre-Colonial metallurgical activity suggested by earlier findings from Bolivia. PMID:17547165

  4. A millennium of metallurgy recorded by lake sediments from Morococha, Peruvian Andes.

    PubMed

    Cooke, Colin A; Abbott, Mark B; Wolfe, Alexander P; Kittleson, John L

    2007-05-15

    To date, information concerning pre-Colonial metallurgy in South America has largely been limited to the archaeological record of artifacts. Here, we reconstruct a millennium of smelting activity in the Peruvian Andes using the lake-sediment stratigraphy of atmospherically derived metals (Pb, Zn, Cu, Ag, Sb, Bi, and Ti) and lead isotopic ratios (206Pb/ 207Pb) associated with smelting from the Morococha mining region in the central Peruvian Andes. The earliest evidence for metallurgy occurs ca. 1000 A.D., coinciding with the fall of the Wari Empire and decentralization of local populations. Smelting during this interval appears to have been aimed at copper and copper alloys, because of large increases in Zn and Cu relative to Pb. A subsequent switch to silver metallurgy under Inca control (ca. 1450 to conquest, 1533 A.D.) is indicated by increases in Pb, Sb, and Bi, a conclusion supported by further increases of these metals during Colonial mining, which targeted silver extraction. Rapid development of the central Andes during the 20th century raised metal burdens by an order of magnitude above previous levels. Our results represent the first evidence for pre-Colonial smelting in the central Peruvian Andes, and corroborate the sensitivity of lake sediments to pre-Colonial metallurgical activity suggested by earlier findings from Bolivia.

  5. A Uniform Conductivity Image along the Chilean Margin? Observations from the Central and Southern Andes

    NASA Astrophysics Data System (ADS)

    Brasse, H.; Soyer, W.

    2001-12-01

    Over the last years a reasonably detailed image of electrical conductivity distribution has been achieved in the central Andes at latitudes 20--22oS. These studies have been complemented by recent magnetotelluric investigations in the southern Chilean Andes (39oS). Despite the different subduction settings concerning e.g., age of subducted plate, trench filling and history of volcanic arcs, the inferred conductivity distributions show remarkable similarities. Higher conductivities assumed to be connected with hydration-dehydration processes are only resolved as a 2nd order effect at larger depths above the downgoing slab. On the other hand, large margin-subparallel fault zones presumably originating from oblique subduction are consistently imaged as good conductors in the mid crust, e.g., the Atacama Fault and the West Fissure in the central Andes and the Liquiñe-Ofqui Fault in the south. The main differences concerning electrical properties between the two subduction settings include the large conductivity anomaly below the Altiplano high plateau in the central Andes and an anisotropic forearc crust in the south, indicated by ystematic deflection of induction arrows. An explanation of the latter phenomenon may possibly be seen in fossil, Cenozoic or even Pre-Andean structures.

  6. New host and lineage diversity of avian haemosporidia in the northern Andes

    PubMed Central

    Harrigan, Ryan J; Sedano, Raul; Chasar, Anthony C; Chaves, Jaime A; Nguyen, Jennifer T; Whitaker, Alexis; Smith, Thomas B

    2014-01-01

    The northern Andes, with their steep elevational and climate gradients, are home to an exceptional diversity of flora and fauna, particularly rich in avian species that have adapted to divergent ecological conditions. With this diversity comes the opportunity for parasites to exploit a wide breadth of avian hosts. However, little research has focused on examining the patterns of prevalence and lineage diversity of avian parasites in the Andes. Here, we screened a total of 428 birds from 19 species (representing nine families) and identified 133 infections of avian haemosporidia (31%), including lineages of Plasmodium, Haemoproteus, and Leucocytozoon. We document a higher prevalence of haemosporidia at higher elevations and lower temperatures, as well as an overall high diversity of lineages in the northern Andes, including the first sequences of haemosporidians reported in hummingbirds (31 sequences found in 11 species within the family Trochilidae). Double infections were distinguished using PHASE, which enables the separation of distinct parasite lineages. Results suggest that the ecological heterogeneity of the northern Andes that has given rise to a rich diversity of avian hosts may also be particularly conducive to parasite diversification and specialization. PMID:25469161

  7. Mapping the Interplay of ET and Topography on Precipitation Processes in the Eastern Andes

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoming; Barros, Ana

    2015-04-01

    We present recent work toward elucidating the role of evapotranspiration in the hydrometeorology of the eastern Andes Mountains using realistic and quasi-idealized ET withdrawal experiments with WRF at very high resolution (~1 km grid spacing). The results show that evapotranspiration fluxes modulated by landform govern moist processes in the lower troposphere, including cloud formation and precipitation processes that account for daily precipitation amounts as high as 50-70% depending on synoptic conditions and season. Using parsimonious model experiments and observations for the Amazon basin and the Central Andes, we demonstrate that vegetation acts as a "terrestrial hydrostat" regulating precipitation locally by controlling atmospheric moist instability, and remotely through changes in atmospheric transport patterns. References Sun, X., and A. P. Barros, 2014a: Isolating the role of surface evapotranspiration on moist convection along the eastern flanks of the tropical Andes using a quasi-idealized approach. J. Atmos. Sci., 72, 243-261. Sun, X., and A. P. Barros, 2014b: Impact of Amazonian evapotranspiration on moisture transport and convection along the eastern flanks of the Andes. Q. J. R. Meteorol. Soc., In Review.

  8. Evolution of crustal thickening in the central Andes, Bolivia

    NASA Astrophysics Data System (ADS)

    Eichelberger, Nathan; McQuarrie, Nadine; Ryan, Jamie; Karimi, Bobak; Beck, Susan; Zandt, George

    2015-09-01

    Paleoelevation histories from the central Andes in Bolivia have suggested that the geodynamic evolution of the region has been punctuated by periods of large-scale lithospheric removal that drive rapid increases in elevation at the surface. Here, we evaluate viable times and locations of material loss using a map-view reconstruction of the Bolivian orocline displacement field to forward-model predicted crustal thicknesses. Two volumetric models are presented that test assumed pre-deformation crustal thicknesses of 35 km and 40 km. Both models predict that modern crustal thicknesses were achieved first in the northern Eastern Cordillera (EC) by 30-20 Ma but remained below modern in the southern EC until ≤10 Ma. The Altiplano is predicted to have achieved modern crustal thickness after 10 Ma but only with a pre-deformation thickness of 50 km, including 10 km of sediment. At the final stage, the models predict 8-25% regional excess crustal volume compared to modern thickness, largely concentrated in the northern EC. The excess predicted volume from 20 to 0 Ma can be accounted for by: 1) crustal flow to the WC and/or Peru, 2) localized removal of the lower crust, or 3) a combination of the two. Only models with initial crustal thicknesses >35 km predict excess volumes sufficient to account for potential crustal thickness deficits in Peru and allow for lower crustal loss. However, both initial thickness models predict that modern crustal thicknesses were achieved over the same time periods that paleoelevation histories indicate the development of modern elevations. Localized removal of lower crust is only necessary in the northern EC where crustal thickness exceeds modern by 20 Ma, prior to paleoelevation estimates of modern elevations by 15 Ma. In the Altiplano, crustal thicknesses match modern values at 10 Ma and can only exceed modern values by 5 Ma, post-dating when modern elevations were thought to have been established. Collectively, these models predict that

  9. Neotectonic transformation of Cenozoic fold structures in the northwestern Caucasus

    NASA Astrophysics Data System (ADS)

    Trikhunkov, Ya. I.

    2016-09-01

    The performed morphotectonic regionalization of the northwestern Caucasus shows that the fold structures directly expressed in the topography of the territory and continuing to evolve under the settings of contemporary lateral shortening predominate in the northwestern Caucasus. A map of fold structures expressed in the topography of the northwestern Caucasus is presented. The districts distinguished therein correspond to the largest regional tectonic units, the fold topography of which occurs at various stages of tectonic evolution from primary brachyanticlinal ridges of the Taman and Sochi districts to the complex fold-thrust and inversion fold ridges of the axial zone. Data on active newly formed fold and inversion structures are given. These inherited structures develop under the combined action of selective denudation, beddingplane upthrow faulting, and thrusting.

  10. Hydrological cycles and trends in the NW Argentine Andes since 1940

    NASA Astrophysics Data System (ADS)

    Castino, Fabiana; Bookhagen, Bodo; Strecker, Manfred

    2016-04-01

    Strong spatiotemporal variability characterizes the hydrometeorological pattern in the NW Argentine Andes, draining parts of the most populated and economically important areas of South America. During the summer monsoon season (DJF), the eastern flanks of the central Andes are characterized by deep convection, exposing them to extreme hydrometeorological events. These often result in floods and landslides with disastrous effects on the local populations. Here, we analyze river discharge to explore long-term hydrological variability in NW Argentine Andes and the linked climate controlling processes. We rely on 13 daily river discharge time series relevant to drainage basins spanning several size orders (102-104 km2) starting in 1914 and define different hydro-climate indices both for the mean and the extreme hydrological events. We apply quantile regression to investigate long-term trends and spectral analysis associated with cross-correlation with SST-based climate indices to identify links to large-scale climate variability modes. River discharge presents a pronounced and coherent variability signal in South America, particularly for wide drainage basins, such as the Amazon and Paraná/La Plata rivers, strongly associated to Pacific and Atlantic Oceans Sea Surface Temperature (SST) anomalies (i.e. ENSO, PDO, AMO). Our analysis evidences that in the NW Argentine Andes, mean discharge values are characterized by statistically significant, mostly positive, long-term trends since 1940, whereas the extreme events present a more non-unidirectional trend pattern. Also, coherent multi-annual to multi-decadal cycles characterizing the discharge pattern have been identified, suggesting that processes linked to SST anomaly-modes strongly control the hydrometeorology variability in the NW Argentina Andes.

  11. Venezuelan Equine Encephalitis Virus Replicon Particle Vaccine Protects Nonhuman Primates from Intramuscular and Aerosol Challenge with Ebolavirus

    PubMed Central

    Herbert, Andrew S.; Kuehne, Ana I.; Barth, James F.; Ortiz, Ramon A.; Nichols, Donald K.; Zak, Samantha E.; Stonier, Spencer W.; Muhammad, Majidat A.; Bakken, Russell R.; Prugar, Laura I.; Olinger, Gene G.; Groebner, Jennifer L.; Lee, John S.; Pratt, William D.; Custer, Max; Kamrud, Kurt I.; Smith, Jonathan F.; Hart, Mary Kate

    2013-01-01

    There are no vaccines or therapeutics currently approved for the prevention or treatment of ebolavirus infection. Previously, a replicon vaccine based on Venezuelan equine encephalitis virus (VEEV) demonstrated protective efficacy against Marburg virus in nonhuman primates. Here, we report the protective efficacy of Sudan virus (SUDV)- and Ebola virus (EBOV)-specific VEEV replicon particle (VRP) vaccines in nonhuman primates. VRP vaccines were developed to express the glycoprotein (GP) of either SUDV or EBOV. A single intramuscular vaccination of cynomolgus macaques with VRP expressing SUDV GP provided complete protection against intramuscular challenge with SUDV. Vaccination against SUDV and subsequent survival of SUDV challenge did not fully protect cynomolgus macaques against intramuscular EBOV back-challenge. However, a single simultaneous intramuscular vaccination with VRP expressing SUDV GP combined with VRP expressing EBOV GP did provide complete protection against intramuscular challenge with either SUDV or EBOV in cynomolgus macaques. Finally, intramuscular vaccination with VRP expressing SUDV GP completely protected cynomolgus macaques when challenged with aerosolized SUDV, although complete protection against aerosol challenge required two vaccinations with this vaccine. PMID:23408633

  12. Age-specific prevalence of Escherichia coli with localized and aggregative adherence in Venezuelan infants with acute diarrhea.

    PubMed

    González, R; Díaz, C; Mariño, M; Cloralt, R; Pequeneze, M; Pérez-Schael, I

    1997-05-01

    To evaluate the epidemiological significance of HEp-2 cell-adherent Escherichia coli isolates in diarrheal disease, we performed a study with 513 Venezuelan infants with diarrhea and 241 age-matched controls to determine the prevalence of enteropathogenic E. coli (enteroadherent E. coli, enterotoxigenic E. coli, enteroinvasive E. coli, and enterohemorrhagic E. coli) and their correlation with O:H serotypes. E. coli isolates exhibiting localized and aggregative adherence in the HEp-2 cell assay were significantly more frequently isolated from the patients (8.5 and 26.9%, respectively) than from the controls (1.7 and 15%, respectively). This difference was significant for the group 0 to 2 months of age but for older infants. Regardless of age, E. coli isolates with diffuse adherence were found at similar frequencies in both the patients and the controls. A striking correlation between classic O serogroups and localized adherence was also observed. These findings confirm the pathogenic role of E. coli with localized and aggregative adherence in diarrheal disease, as well as the epidemiological importance of O:H serotyping for characterizing localized-adhering E. coli.

  13. Geology reinterpretation of an inactive old field-Mata 3, Venezuelan East Basin-using computer methods

    SciTech Connect

    Rodriguez, O.; Rivero, C.; Abud, J.

    1996-08-01

    Nowadays to find a new oil field is a very dificult task that the petroleum people know very well; therefore the reactivation of an old oil field that had important production is the best way to increase the economic benefits for the Corporation and for the country in general. In this paper, the most important point was the Geology Study regarding the reopening of the Mata-3 oil field, which ceased to be active 15 years ago, after producing 30 mmbls of light oil. There are 30 prospective sands but only 3 of them have produced 70% of the primary production. Thus, the principal objectives were the S2, S3, 4 sands of Oficina Formation (Venezuelan East Basin) in 476 wells located in this area. The following computer systems that were available to us: GIPSIE System, Vax (Intergraph Co.); PMSE System, Vax (Intergraph Co.); CPS-3 System, Unix (Radian Co.); and SIGEMAP System PC (Corpoven, S.A.). All of them assist in the different tasks that must be done by the geologists working in the interpretation area. In the end, we recommended 40 wells to workover (2 wells/year for 20 years) and thereby to increase the POI (petroleum in situ) and increase the reserves by 13.4 mmbls of fight oil, important commercial production. The estimate of the total investment is about $2 million (340 mmBs.).

  14. Effects of ingestion of chlorocholine chloride and cyclophosphamide on Venezuelan equine encephalitis virus infections in deer mice (Peromyscus maniculatus).

    PubMed

    Fairbrother, A; Yuill, T M; Olson, L J

    1984-05-01

    We investigated the effects of chlorocholine chloride (CCC), a plant growth regulator, and cyclophosphamide (CP), a known immunosuppressant, on the ability of deer mice (Peromyscus maniculatus) to resist challenge with a sublethal dose of Venezuelan equine encephalitis virus ( VEEV ). The toxicants were continuously delivered in low doses in the feed; CP at 20 mg/kg body wt/day and CCC at 1, 10, 20 or 40 mg/kg body wt/day. Mice were inoculated with 3 X 10(4) plaque forming units (pfu) of VEEV after eating experimental feed for 23 days. Mice were bled daily for 7 days and at selected intervals from 8 to 63 days post inoculation (PI) for viremia and antibody titer determinations. CP treatment increased the duration of viremia and significantly (P less than or equal to 0.05) decreased mean viremia titers. Antibody titers were significantly (P less than or equal to 0.05) depressed in CP-treated mice compared to controls. CP treatment increased mortality. CCC had no effect on viremia duration or titer except when given in doses of 1 mg/kg body wt/day when it significantly (P less than or equal to 0.05) decreased mean viremia titers compared to controls. Early antibody responses were increased by CCC treatment except in the 10 mg/kg body wt/day treatment group in which titers were decreased. By 30 days PI antibody titers of CCC-treated mice were no different from controls. PMID:6729837

  15. A preliminary study of haemolymph from four Venezuelan populations of Panstrongylus geniculatus Latreille, 1811 (Hemiptera: Reduviidae) and its epidemiological significance.

    PubMed

    Reyes-Lugo, Matías; Girón, M C María E; Kamiya, Haruo; Rodríguez-Acosta, Alexis

    2006-01-01

    SDS-PAGE profiles of both sexes of the haemolymphs of Panstrongylus geniculatus from different Venezuelan regions (savannas, piedmont, tropical forest and urban areas) were compared. It was determined that the haemolymphs showed a different electrophoretic profile, with proteins that ranged from 14 to 164 kDa. The most representative protein band in the profile of females was observed in two sectors: between 164 and 46 kDa and between 33 and 30 kDa. The main illustrative protein band in males was observed in one region: from 46 to 35 kDa. The Haemolymph composition of P. geniculatus from populations evaluated in this work expressed high homogeneity of this species with a clear difference between males and females. This similarity may be useful for control of these insects, taking into account that the genetic stability may be very important, since the use of an insecticide in a population with these characteristics is always more successful. According to the bibliographic review, this is the first study of haemolymph from Panstrongylus geniculatus.

  16. High-resolution Adjoint Tomography of the Eastern Venezuelan Crust using Empirical Green's Function Waveforms from Ambient Noise Interferometry

    NASA Astrophysics Data System (ADS)

    Chen, M.; Masy, J.; Niu, F.; Levander, A.

    2014-12-01

    We present a high-resolution 3D crustal model of Eastern Venezuela from a full waveform inversion adjoint tomography technique, based on the spectral-element method. Empirical Green's functions (EGFs) of Rayleigh waves from ambient noise interferometry serve as the observed waveforms. Rayleigh wave signals in the period range of 10 - 50 s were extracted by cross-correlations of 48 stations from both Venezuelan national seismic network and the BOLIVAR project array. The synthetic Green's functions (SGFs) are calculated with an initial regional 3D shear wave model determined from ballistic Rayleigh wave tomography from earthquake records with periods longer than 20 s. The frequency-dependent traveltime time misfits between the SGFs and EGFs are minimized iteratively using adjoint tomography = to refine 3D crustal structure [Chen et al. 2014]. The final 3D model shows lateral shear wave velocity variations that are well correlated with the geological terranes within the continental interior. In particular, the final model reveals low velocities distributed along the axis of the Espino Graben, indicating that the graben has a substantially different crustal structure than the rest of the Eastern Venezuela Basin. We also observe high shear velocities in the lower crust beneath some of the subterranes of the Proterozoic-Archean Guayana Shield.

  17. Trypanosomiasis in Venezuelan water buffaloes: association of packed-cell volumes with seroprevalence and current trypanosome infection.

    PubMed

    García, H; García, M-E; Pérez, G; Bethencourt, A; Zerpa, E; Pérez, H; Mendoza-León, A

    2006-06-01

    The seroprevalence of trypanosomiasis and the prevalence of current trypanosome infection in water buffaloes from the most important livestock areas of Venezuela were evaluated by IFAT and the microhaematocrit centrifugation technique, respectively. The usefulness of a PCR-based assay for identifying the trypanosome species in the buffaloes was also evaluated. Of the 644 animals investigated, 40 (6.2%) were found infected with trypanosomes by blood centrifugation, and 196 (30.4%) were found positive for anti-trypanosome antibodies, by IFAT. The results of the PCR-based assay indicated that 92.5% of the animals with current infections were infected with Trypanosoma vivax and the rest with T. theileri (the first molecular confirmation of T. theileri in Venezuelan water buffaloes). The national programme to treat and prevent trypanosome infections in the buffaloes does not appear to be meeting with great success, even though it is focused on T. vivax. Although the level of parasitaemia was categorized as low for 28 (70%) of the infections detected (and packed-cell volumes appeared to be unassociated with IFAT result, and uncorrelated, in the infected animals, with level of parasitaemia), the 40 infected buffaloes had a significantly lower mean packed-cell volume than the uninfected animals (P<0.05). Farmers should therefore be made aware of the probability of trypanosome-attributable losses in buffalo productivity.

  18. Water and sediment quality of the Lake Andes and Choteau Creek basins, South Dakota, 1983-2000

    USGS Publications Warehouse

    Sando, Steven Kent; Neitzert, Kathleen M.

    2003-01-01

    The Bureau of Reclamation has proposed construction of the Lake Andes/Wagner Irrigation Demonstration Project to investigate environmental effects of irrigation of glacial till soils substantially derived from marine shales. During 1983-2000, the U.S. Geological Survey collected hydrologic, water-quality, and sediment data in the Lake Andes and Choteau Creek Basins, and on the Missouri River upstream and downstream from Choteau Creek, to provide baseline information in support of the proposed demonstration project. Lake Andes has a drainage area of about 230 mi2 (square miles). Tributaries to Lake Andes are ephemeral. Water-level fluctuations in Lake Andes can be large, and the lake has been completely dry on several occasions. The outlet aqueduct from Lake Andes feeds into Garden Creek, which enters Lake Francis Case just upstream from Fort Randall Dam on the Missouri River. For Lake Andes tributary stations, calcium, magnesium, and sodium are approximately codominant among the cations, and sulfate is the dominant anion. Dissolved-solids concentrations typically range from about 1,000 mg/L (milligrams per liter) to about 1,700 mg/L. Major-ion concentrations for Lake Andes tend to be higher than the tributaries and generally increase downstream in Lake Andes. Proportions of major ions are similar among the different lake units (with the exception of Owens Bay), with calcium, magnesium, and sodium being approximately codominant among cations, and sulfate being the dominant anion. Owens Bay is characterized by a calcium sulfate water type. Dissolved-solids concentrations for Lake Andes typically range from about 1,400 to 2,000 mg/L. Whole-water nitrogen and phosphorus concentrations are similar among the Lake Andes tributaries, with median whole-water nitrogen concentrations ranging from about 1.6 to 2.4 mg/L, and median whole-water phosphorus concentrations ranging from about 0.5 to 0.7 mg/L. Whole-water nitrogen concentrations in Lake Andes are similar among the

  19. 40 CFR 81.126 - Northwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Northwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.126 Northwestern Oklahoma Intrastate Air Quality Control Region. The Northwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  20. 40 CFR 81.126 - Northwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false Northwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.126 Northwestern Oklahoma Intrastate Air Quality Control Region. The Northwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  1. 40 CFR 81.126 - Northwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Northwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.126 Northwestern Oklahoma Intrastate Air Quality Control Region. The Northwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  2. 40 CFR 81.126 - Northwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Northwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.126 Northwestern Oklahoma Intrastate Air Quality Control Region. The Northwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  3. 40 CFR 81.126 - Northwestern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Northwestern Oklahoma Intrastate Air... Air Quality Control Regions § 81.126 Northwestern Oklahoma Intrastate Air Quality Control Region. The Northwestern Oklahoma Intrastate Air Quality Control Region consists of the territorial area encompassed by...

  4. The ribbon continent of northwestern South America

    NASA Astrophysics Data System (ADS)

    Altamira-Areyan, Armando

    The tectonic structure of the Plate Boundary Zone (PBZ) between the Caribbean Plate (CARIB) and the South American Plate (SOAM) is interpreted using models that require CARIB motion from the Pacific into the Atlantic. Those models can be subdivided into: (1) those in which the island arc rocks that are now in the CARIB-SOAM PBZ have collided with the northern South America margin, either obliquely or directly during the Cretaceous or during the Cenozoic, and (2) those in which the island arc rocks now in the CARIB-SOAM PBZ collided with the west coast of South America during the Cretaceous and were transferred to the northern margin by transform motion during the Cenozoic. Magnetic anomalies were first rotated in the Central and South Atlantic, holding Africa fixed to establish how much NOAM had converged on SOAM during the Cenozoic. WSW convergence was discovered to have been accommodated in the northern boundary of the CARIB. There is no evidence of convergence in the form of Cenozoic island arc igneous rocks on the north coast of South America. Those results are consistent only with models of Class (2) that call for transform movement of material that had collided with the west coast of South America along the CARIB-SOAM PBZ on the northern margin of South America. 40Ar/39Ar ages of island arc rocks from northern Venezuela were found to be older than ca 70 Ma, which is consistent with a requirement of models of Class (2) that those rocks are from an island arc which collided with the west coast of South America during Cretaceous times. Testing that conclusion using data from Ecuador, Colombia, Venezuela, the Netherlands Antilles, Trinidad and Tobago has led to the construction of a new ribbon continent model of the northwestern Cordillera of South America. Because the part of the ribbon continent on the north coast of South America has been experiencing substantial deformation in the Maracaibo block during the past 10 m.y., structures in that body have had to be

  5. Late Oligocene-Early Miocene compressional tectosedimentary episode and associated land-mammal faunas in the Andes of central Chile and adjacent Argentina (32 37°s)

    NASA Astrophysics Data System (ADS)

    Semper, Thierry; Marshall, Larry G.; Rivano, Sergio; Godoy, Estanislao

    1994-01-01

    A reassessment of the geologic and land-mammal fossil evidence used in attribution of a tectosedimentary episode in the Andes between 32 and 37°S to the Middle Eocene "Incaic tectonic phase" of Peru indicates that the episode occurred during Late Oligocene-Early Miocene times(~ 27-20 Ma). From west to east, three structural domains are recognized for this time span in the study area: a volcanic arc (Chile); a thin-skinned, E-verging fold-thrust belt (Cordillera Principal, Chile-Argentina border strip); and a foreland basin (Argentina). Initiation of thrusting in the Cordillera Principal fold-thrust belt produced the coeval initiation of sedimentation in the foreland basin of adjacent Argentina. This onset of foreland deposition postdates strata bearing a Divisaderan Land Mammal Age fauna (i.e. ~ 35-30 Ma) and is marked at ~ 36°30'S by the base of the "Rodados Lustrosos" conglomerates, which are conformably overlain by sedimentary rocks containing a Deseadan Land Mammal Age fauna (i.e. ~ 29-21 Ma). Geologic relationships between the thick volcanic Abanico (Coya-Machalí) and Farellones formations also demonstrate that this tectosedimentary episode practically ended at ~ 20 Ma at least in the volcanic arc, and was therefore roughly coeval with the major tectonic crisis (~ 27-19 Ma) known in northwestern Andean Bolivia some 1500 km to the north. This strongly suggests that a long, outstanding tectonic upheaval affected at least an extended 12-37°S segment of the Andean margin of South America during Late Oligocene and Early Miocene times.

  6. Screening for new accumulator plants in Andes Range mines

    NASA Astrophysics Data System (ADS)

    Bech, Jaume; Roca, Núria

    2016-04-01

    accumulated considerable concentrations of Cu and Zn. The species from the genus Bidens (Asteraceae) were able not only to accumulate high shoot As concentrations (> 1000 μg g-1 in B. cynapiifolia from Peru) but also considerable amounts of Pb (B. humilis from Chile). The highest Cu shoot concentrations were found in Mullinum spinosum (870 μg g-1) and in B. cynapiifolia (620 μg g-1). The shoot accumulation of Zn was highest in Baccharis amdatensis (>1900 μg g-1) and in Rumex crispus (1300 μg g-1) from the Ag mine in Ecuador (Bech et al., 2002). In the Peruvian Andes, B. triplinervia can be considered interesting for phytostabilization, due to its capacity to restrict the accumulation of elevated amounts of Pb and Zn in the shoots.

  7. The Largest Holocene Eruption of the Central Andes Found

    NASA Astrophysics Data System (ADS)

    Fernandez-Turiel, J.; Rodriguez-Gonzalez, A.; Saavedra, J.; Perez-Torrado, F.; Carracedo, J.; Osterrieth, M.; Carrizo, J.; Esteban, G.

    2013-12-01

    We present new data and interpretation about a major eruption -spreading ˜110 km3 ashes over 440.000 km2- long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in NW Argentina. This eruption may be the biggest during the past five millennia in the Central Volcanic Zone of the Andes, and possibly one of the largest Holocene eruptions in the world. The environmental effects of this voluminous eruption are still noticeable, as evidenced by the high content of arsenic and other trace elements in the groundwaters of the Chacopampean Plain. The recognition of this significant volcanic event may shed new light on interpretations of critical changes observed in the mid-Holocene paleontological and archaeological records, and offers researchers an excellent, extensive regional chronostratigraphic marker for reconstructing mid-Holocene geological history over a wide geographical area of South America. More than 100 ashes were sampled in Argentina, Chile and Uruguay during different field campaigns. Ash samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), grain size distributions laser diffraction, and geochemically by electron microprobe (EMPA) and laser ablation-HR-ICP-MS. New and published 14C ages were calibrated to calendar years BP. The age of the most recent CBVC eruption is 4407-4093 cal y BP, indirectly dated by 14C of associated organic sediment within the lower part of a proximal fall deposit of this event (26°53'16.05"S-67°44'48.68"W). This is the youngest record of a major volcanic event in the Southern Puna. This age is consistent with other radiocarbon dates of organic matter in palaeosols underlying or overlying distal ash fall deposits. Based on their products, all of rhyolitic composition, we have distinguished 8 main episodes during the evolution of the most recent CBVC eruption: 1) the eruption began with a white rhyolite lava dome extrusion; 2) followed by a Plinian

  8. Methane and nitrous oxide fluxes from the tropical Andes

    NASA Astrophysics Data System (ADS)

    Teh, Y. A.; Diem, T.; Jones, S.; Huaraca Quispe, L. P.; Baggs, E.; Morley, N.; Richards, M.; Smith, P.; Meir, P.

    2013-11-01

    Remote sensing and inverse modelling studies indicate that the tropics emit more CH4 and N2O than predicted by bottom-up emissions inventories, suggesting that terrestrial sources are stronger or more numerous than previously thought. Tropical uplands are a potentially large and important source of CH4 and N2O often overlooked by past empirical and modelling studies. To address this knowledge gap, we investigated spatial, temporal and environmental trends in CH4 and N2O fluxes across a~long elevation gradient (600-3700 m a.s.l.) in the Kosñipata Valley, in the southern Peruvian Andes that experiences seasonal fluctuations in rainfall. The aim of this work was to produce preliminary estimates of CH4 and N2O fluxes from representative habitats within this region, and to identify the proximate controls on soil CH4 and N2O dynamics. Ecosystems across this altitudinal gradient were both atmospheric sources and sinks of CH4 on an annual basis. Montane grasslands (or, puna; 3200-3700 m a.s.l.) were strong atmospheric sources, emitting 56.94 ± 7.81kg CH4-C ha-1 yr-1. Upper montane forest (2200-3200 m a.s.l.) and lower montane forest (1200-2200 m a.s.l.) were net atmospheric sinks (-2.99 ± 0.29 kg CH4-C ha-1 yr-1 and -2.34 ± 0.29 kg CH4-C ha-1 yr-1, respectively); while premontane forests (600-1200 m a.s.l.) fluctuated between source or sink depending on the season (wet season: 1.86 ± 1.50 CH4-C ha-1 yr-1; dry season: -1.17 ± 0.40 CH4-C ha-1 yr-1). Analysis of spatial, temporal and environmental trends in CH4 flux across the study site suggest that soil redox was a dominant control on net CH4 flux. CH4 emissions were greatest from elevations, landforms and during times of year when soils were sub-oxic, and CH4 efflux was inversely correlated with soil O2 concentration (r2 = 0.82, F1, 125 = 588.41, P < 0.0001). Ecosystems across the region were net atmospheric N2O sources. N2O fluxes declined with increasing elevation; N2O emissions from premontane forest, lower

  9. Screening for new accumulator plants in Andes Range mines

    NASA Astrophysics Data System (ADS)

    Bech, Jaume; Roca, Núria

    2016-04-01

    accumulated considerable concentrations of Cu and Zn. The species from the genus Bidens (Asteraceae) were able not only to accumulate high shoot As concentrations (> 1000 μg g-1 in B. cynapiifolia from Peru) but also considerable amounts of Pb (B. humilis from Chile). The highest Cu shoot concentrations were found in Mullinum spinosum (870 μg g-1) and in B. cynapiifolia (620 μg g-1). The shoot accumulation of Zn was highest in Baccharis amdatensis (>1900 μg g-1) and in Rumex crispus (1300 μg g-1) from the Ag mine in Ecuador (Bech et al., 2002). In the Peruvian Andes, B. triplinervia can be considered interesting for phytostabilization, due to its capacity to restrict the accumulation of elevated amounts of Pb and Zn in the shoots.

  10. A phylogenetic analysis using full-length viral genomes of South American dengue serotype 3 in consecutive Venezuelan outbreaks reveals novel NS5 mutation

    PubMed Central

    Schmidt, DJ; Pickett, BE; Camacho, D; Comach, G; Xhaja, K; Lennon, NJ; Rizzolo, K; de Bosch, N; Becerra, A; Nogueira, ML; Mondini, A; da Silva, EV; Vasconcelos, PF; Muñoz-Jordán, JL; Santiago, GA; Ocazionez, R; Gehrke, L; Lefkowitz, EJ; Birren, BW; Henn, MR; Bosch, I

    2013-01-01

    Dengue virus currently causes 50-100 million infections annually. Comprehensive knowledge about the evolution of Dengue in response to selection pressure is currently unavailable, but would greatly enhance vaccine design efforts. In the current study, we sequenced 187 new dengue virus serotype 3(DENV-3) genotype III whole genomes isolated from Asia and the Americas. We analyzed them together with previously-sequenced isolates to gain a more detailed understanding of the evolutionary adaptations existing in this prevalent American serotype. In order to analyze the phylogenetic dynamics of DENV-3 during outbreak periods; we incorporated datasets of 48 and 11 sequences spanning two major outbreaks in Venezuela during 2001 and 2007-2008 respectively. Our phylogenetic analysis of newly sequenced viruses shows that subsets of genomes cluster primarily by geographic location, and secondarily by time of virus isolation. DENV-3 genotype III sequences from Asia are significantly divergent from those from the Americas due to their geographical separation and subsequent speciation. We measured amino acid variation for the E protein by calculating the Shannon entropy at each position between Asian and American genomes. We found a cluster of 7 amino acid substitutions having high variability within E protein domain III, which has previously been implicated in serotype-specific neutralization escape mutants. No novel mutations were found in the E protein of sequences isolated during either Venezuelan outbreak. Shannon entropy analysis of the NS5 polymerase mature protein revealed that a G374E mutation, in a region that contributes to interferon resistance in other flaviviruses by interfering with JAK-STAT signaling was present in both the Asian and American sequences from the 2007-2008 Venezuelan outbreak, but was absent in the sequences from the 2001 Venezuelan outbreak. In addition to E, several NS5 amino acid changes were unique to the 2007-2008 epidemic in Venezuela and may

  11. Precipitation variability in the Peruvian Andes under future climatic conditions - Assessment and implications

    NASA Astrophysics Data System (ADS)

    Neukom, Raphael; Rohrer, Mario; Salzmann, Nadine; Calanca, Pierluigi; Huggel, Christian; Acuña, Delia

    2014-05-01

    The Peruvian Andes are characterized by pronounced dry and wet seasons. Agriculture but also other economic sectors such as hydropower production strongly depend on water availability, and are therefore sensitive to changes in precipitation regime at the local and regional scale. Future changes in rainfall amounts and variability may have severe consequences for society and need to be assessed in order to develop adequate strategies for adaptation. The precipitation regime of the high Peruvian Andes is characterized by a complex interplay of local orographic effects with large-scale circulation. A main moisture source for the region is the Amazon Basin and the amount of moisture received in the Central Andes is influenced by the strength of zonal winds in the upper troposphere. As a result, variations in seasonal precipitation amounts can be associated to the South American Monsoon and large-scale teleconnections with the oceans surrounding the South American continent. Notably, however, direct correlations of local precipitation with ENSO, the main driver of tropical Pacific variability, are mostly weak and unstable over the short instrumental period. In this contribution we provide an assessment of future changes in precipitation amounts and variability of the southern Peruvian Andes in relation to changes in the large-scale atmospheric circulation, quantify the associated uncertainties and discuss some of the implications for society. The analysis relies on climate change projections from the CMIP5 initiative. We show that owing to the complex dynamic influence on local climate and the distinct, small-scaled topographic features of the Andes, Global Climate Models (GCMs) have limited ability to adequately simulate precipitation variability at the local scale. Accordingly, uncertainties in simulated precipitation patterns are considerable. More reliable is the simulation of the mid and upper tropospheric flow, as shown by comparing the model output with global re

  12. The growth of the central Andes 22-26°S (Invited)

    NASA Astrophysics Data System (ADS)

    Quade, J.; DeCelles, P. G.; Carrapa, B.; Murray, K. E.; Canavan, R. R.; Huntington, K. W.; Gehrels, G. E.

    2013-12-01

    In this talk we synthesize geologic observations with new isotopic evidence for the timing and magnitude of uplift for the central Andes between 22-26°S since the Paleocene. To estimate paleoelevations we used the stable isotopic composition of carbonates and volcanic glass, combined with another paleoelevation indicator for the central Andes: the distribution of evaporites. Paleoelevation reconstruction using clumped isotope paleothermometry failed due to resetting during burial. The Andes at this latitude rose and broadened eastward in three stages during the Cenozoic. The first, in what is broadly termed the 'Incaic' Orogeny, ended by the late Eocene, when magmatism and deformation had elevated to ≥ 4 km the bulk (~50%) of what is now the western and central Andes. The second stage witnessed the gradual building of the easternmost Puna and Eastern Cordillera to > 3 km by no later than 15 Ma. The proximal portions of the Paleogene foreland basin system were uplifted and hydrographically isolated from easterly moisture sources, promoting the precipitation of evaporites. In the third orogenic stage during the Plio-Pleistocene, Andean deformation accelerated and stepped eastward to form the modern Subandes, accounting for the final ~15-20% of the current cross-section of the Andes. About 0.5 km of elevation was added unevenly to the Western Cordillera and Puna 10-2 Ma by voluminous volcanism. The two largest episodes of uplift and eastward propagation of the orogenic front and of the foreland flexural wave, ~50 (?)-40 and <5 Ma, overlap with or immediately post-date periods of very rapid plate convergence, high flux magmatism in the magmatic arc, and crustal thickening. Uplift does not correlate with an hypothesized mantle lithospheric foundering event in the early Oligocene. Development of hyperaridity in the Atacama Desert by the mid-Miocene post-dates the two-step elevation gain to >3 km of most (~75%) of the Andes. Hence, the record suggests that hyperarid

  13. Capturing Qualitative Data: Northwestern University Special Libraries' Acknowledgments Database

    ERIC Educational Resources Information Center

    Stigberg, Sara; Guittar, Michelle; Morse, Geoffrey

    2015-01-01

    Assessment and supporting data have become of increasing interest in librarianship. In this paper, we describe the development and implementation of the Northwestern University Library Acknowledgments Database tool, which gathers and documents qualitative data, as well as its component reporting function. This collaborative project and resulting…

  14. 6. SOUTHWEST SIDE PARTIAL ELEVATION OF NORTHWESTERN HALF OF THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SOUTHWEST SIDE -PARTIAL ELEVATION OF NORTHWESTERN HALF OF THE BRIDGE, FROM THE NEW BRIDGE - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  15. Beak deformities in Northwestern Crows: evidence of a multispecies epizootic

    USGS Publications Warehouse

    Van Hemert, Caroline; Handel, Colleen M.

    2010-01-01

    Beak abnormalities are rare among adult birds and, typically, are not widespread in a given population, within a region, or across multiple species. A high concentration of beak deformities was recently documented in Black-capped Chickadees (Poecile atricapillus) and other resident avian species in Alaska. We describe a parallel condition in Northwestern Crows (Corvus caurinus) that signals the emergence of a multispecies epizootic. On the basis of 186 Northwestern Crows captured at six sites in Alaska during 2007 and 2008, we estimated the prevalence of beak deformities in adults to be 16.9 ± 5.3%, the highest rate of gross deformities ever recorded in a wild bird population. Prevalence varied among sites and was as high as 36% on the Kenai Peninsula, which suggests possible epizootic clusters. We also documented beak abnormalities in an additional 148 Northwestern Crows in south-central and southeastern Alaska and in 64 crows near Vancouver, British Columbia, and Puget Sound, Washington, a region where both Northwestern Crows and American Crows (C. brachyrhynchos) occur. The increase in frequency and distribution of crows observed with abnormal beaks throughout the Pacific Northwest since the late 1990s indicates a geographic expansion of this problem. Affected crows exhibited elongated and often crossed beaks that were morphologically similar to deformities documented in Black-capped Chickadees and other species in Alaska over approximately the same period. Additional research is needed to determine the etiology and potential adverse effects on bird populations affected by this disorder.

  16. Northwestern Argentina as seen from the Apollo 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Puna de Atacama area of northwestern Argentina, Provinces of Salta and Catamarca, as seen from the Apollo 7 spacecraft during its 154th revolution of the earth. Photographed from an altitude of 175 nautical miles, at ground elapsed time of 243 hours and 58 minutes.

  17. New provincial records of skinks (Squamata: Scincidae) from northwestern Vietnam

    PubMed Central

    Pham, Anh Van; Le, Dzung Trung; Nguyen, Son Lan Hung; Ziegler, Thomas

    2015-01-01

    Abstract We report six new records of skinks from northwestern Vietnam: Eutropis macularius, Scincella devorator, S. monticola, S. ochracea, Sphenomorphus cryptotis and S. indicus. Our new findings increase the species number of skinks (Scincidae) to nine in Dien Bien Province and to 14 in Son La Province. We also provide additional natural history data of aforementioned species. PMID:25698899

  18. Phylogeny and biogeography of the New World siskins and goldfinches: rapid, recent diversification in the Central Andes.

    PubMed

    Beckman, Elizabeth J; Witt, Christopher C

    2015-06-01

    Time-calibrated molecular phylogenies can help us to understand the origins of the diverse and unique Andean avifauna. Previous studies have shown that the tempo of diversification differed between the Andes and adjacent lowland regions of South America. Andean taxa were found to have speciated more recently and to have avoided the decelerated diversification that is typical of Neotropical lowland clades. The South American siskins, a Pleistocene finch radiation, may typify this Andean pattern. We investigated the phylogenetic biogeography of all the New World siskins and goldfinches in new detail. To understand the specific role of the Andes in siskin diversification, we asked: (1) Was diversification faster in Andean siskin lineages relative to non-Andean ones? (2) Did siskin lineages move into and out of the Andes at different rates? We found that siskin lineages in the Andes had higher diversification rates and higher outward dispersal rates than siskin lineages outside the Andes. We conclude that páramo expansion and contraction in response to Pleistocene climatic cycles caused accelerated diversification and outward dispersal in Andean siskins. The younger average age of bird species in the Andes compared to lowland South America may be attributable to bursts of recent diversification in siskins and several other vagile, open-habitat clades.

  19. Sediment yield along the Andes: continental budget, regional variations, and comparisons with other basins from orogenic mountain belts

    NASA Astrophysics Data System (ADS)

    Latrubesse, Edgardo M.; Restrepo, Juan D.

    2014-07-01

    We assess the sediment yield at 119 gauging stations distributed from Colombia to Patagonia, covering the different morphotectonic and morphoclimatic settings of the Andes. The most productive areas are the Meta River basin within the northern Andes and the Bolivian and northern Argentina-Chaco systems, which produce an average of 3345, 4909 and 2654 t km2 y- 1 of sediment, respectively. The rivers of the northern and central Andes (excluding the Pacific watersheds of Peru, northern Chile, and central Argentina) have a weighted mean sediment yield of 2045 t km- 2 y- 1 and produce 2.25 GTy- 1 of total sediment. A major constraint estimating the Andean continental budget of sediment yield lies in the lack of gauging data for the Peruvian region. Using the available gauge stations, the regional sediment yield appears underestimated. Assuming a higher value of sediment yield for the Peruvian Andes, the total budget for the whole central Andes could range between 2.57 GT y- 1 and 3.44 GT y- 1. A minimum of ~ 0.55 GT y- 1 and a probable maximum of ~ 1.74 GT y- 1 of sediment are deposited in the intramontane and surrounding proximal sedimentary basins. The magnitude of sediment yield in the Andes is comparable to other rivers draining orogenic belts around the world.

  20. Phylogeny and biogeography of the New World siskins and goldfinches: rapid, recent diversification in the Central Andes.

    PubMed

    Beckman, Elizabeth J; Witt, Christopher C

    2015-06-01

    Time-calibrated molecular phylogenies can help us to understand the origins of the diverse and unique Andean avifauna. Previous studies have shown that the tempo of diversification differed between the Andes and adjacent lowland regions of South America. Andean taxa were found to have speciated more recently and to have avoided the decelerated diversification that is typical of Neotropical lowland clades. The South American siskins, a Pleistocene finch radiation, may typify this Andean pattern. We investigated the phylogenetic biogeography of all the New World siskins and goldfinches in new detail. To understand the specific role of the Andes in siskin diversification, we asked: (1) Was diversification faster in Andean siskin lineages relative to non-Andean ones? (2) Did siskin lineages move into and out of the Andes at different rates? We found that siskin lineages in the Andes had higher diversification rates and higher outward dispersal rates than siskin lineages outside the Andes. We conclude that páramo expansion and contraction in response to Pleistocene climatic cycles caused accelerated diversification and outward dispersal in Andean siskins. The younger average age of bird species in the Andes compared to lowland South America may be attributable to bursts of recent diversification in siskins and several other vagile, open-habitat clades. PMID:25796324

  1. Bullying victimization and physical fighting among Venezuelan adolescents in Barinas: results from the Global School-Based Health Survey 2003

    PubMed Central

    2009-01-01

    Background Violence among adolescents has untoward psycho-social and physical health effects among this age group. Most of the literature on this topic has been from high-income nations, and little information has come from middle- and low-income nations. This study was done to assess the relationship between physical fighting and bullying victimization among Venezuelan school-going adolescents in Barinas. Method We used data from the 2003 Global School-Based Health Survey conducted among in-school adolescents in Barinas, Venezuela. We estimated the prevalence of bullying victimization and physical fighting. We also conducted Logistic regression analysis to assess the association between a selected list of explanatory variables and physical fighting. We hypothesized that there would be a dose-response relationship between physical fighting and number of times the adolescent reported being a bullied in the past 30 days. Results A total of 2,249 adolescent students participated in the survey. However data on sex (gender) were available for only 2,229 respondents, of whom 31.2 (47.4% males and 17.0% females) reported having been involved in a physical fight in the last 12 months. Some 31.5% (37.0% males and 27.0% females) reported having been bullied in the past 30 days. There was a dose-response relationship between bullying victimization and physical fighting (p-trend < 0.001). Compared to subjects who were not bullied, those who reported being bullied were more likely to engage in physical fighting after controlling for age, sex, substance use (smoking, alcohol drinking or drug use), and parental supervision. Conclusion Physical fighting and bullying victimization experience is common among in-school adolescents in Barinas, Venezuela. The fact that victims of bullying were more likely to have engaged in physical fighting may be evidence supporting the notion that "violence begets more violence". PMID:19939261

  2. A humanized murine monoclonal antibody protects mice either before or after challenge with virulent Venezuelan equine encephalomyelitis virus.

    PubMed

    Hunt, Ann R; Frederickson, Shana; Hinkel, Christopher; Bowdish, Katherine S; Roehrig, John T

    2006-09-01

    A humanized monoclonal antibody (mAb) has been developed and its potential to protect from or cure a Venezuelan equine encephalomyelitis virus (VEEV) infection was evaluated. The VEEV-neutralizing, protective murine mAb 3B4C-4 was humanized using combinatorial antibody libraries and phage-display technology. Humanized VEEV-binding Fabs were evaluated for virus-neutralizing capacity, then selected Fabs were converted to whole immunoglobulin (Ig) G1, and stable cell lines were generated. The humanized mAb Hy4-26C, designated Hy4 IgG, had virus-neutralizing capacity similar to that of 3B4C-4. Passive antibody protection studies with purified Hy4 IgG were performed in adult Swiss Webster mice. As little as 100 ng Hy4 IgG protected 90 % of mice challenged with 100 intraperitoneal (i.p.) mean morbidity (MD(50)) doses of virulent VEEV (Trinidad donkey) 24 h after antibody transfer; also, 500 mug Hy4 IgG protected 80 % of mice inoculated with 100 intranasal MD(50) doses of VEEV. Moreover, 10 mug passive Hy4 IgG protected 70 % of mice from a VEEV challenge dose as great as 10(7) i.p. MD(50). Hy4 IgG also protected mice from challenge with another epizootic VEEV variety, 1C (P676). Importantly, therapeutic administration of the humanized mAb to mice already infected with VEEV cured 90 % of mice treated with Hy4 IgG within 1 h of VEEV inoculation and 75 % of mice treated 24 h after virus infection. PMID:16894184

  3. Natural infection of Plasmodium brasilianum in humans: Man and monkey share quartan malaria parasites in the Venezuelan Amazon

    PubMed Central

    Lalremruata, Albert; Magris, Magda; Vivas-Martínez, Sarai; Koehler, Maike; Esen, Meral; Kempaiah, Prakasha; Jeyaraj, Sankarganesh; Perkins, Douglas Jay; Mordmüller, Benjamin; Metzger, Wolfram G.

    2015-01-01

    Background The quartan malaria parasite Plasmodium malariae is the widest spread and best adapted human malaria parasite. The simian Plasmodium brasilianum causes quartan fever in New World monkeys and resembles P. malariae morphologically. Since the genetics of the two parasites are nearly identical, differing only in a range of mutations expected within a species, it has long been speculated that the two are the same. However, no naturally acquired infection with parasites termed as P. brasilianum has been found in humans until now. Methods We investigated malaria cases from remote Yanomami indigenous communities of the Venezuelan Amazon and analyzed the genes coding for the circumsporozoite protein (CSP) and the small subunit of ribosomes (18S) by species-specific PCR and capillary based-DNA sequencing. Findings Based on 18S rRNA gene sequencing, we identified 12 patients harboring malaria parasites which were 100% identical with P. brasilianum isolated from the monkey, Alouatta seniculus. Translated amino acid sequences of the CS protein gene showed identical immunodominant repeat units between quartan malaria parasites isolated from both humans and monkeys. Interpretation This study reports, for the first time, naturally acquired infections in humans with parasites termed as P. brasilianum. We conclude that quartan malaria parasites are easily exchanged between humans and monkeys in Latin America. We hypothesize a lack of host specificity in mammalian hosts and consider quartan malaria to be a true anthropozoonosis. Since the name P. brasilianum suggests a malaria species distinct from P. malariae, we propose that P. brasilianum should have a nomenclatorial revision in case further research confirms our findings. The expansive reservoir of mammalian hosts discriminates quartan malaria from other Plasmodium spp. and requires particular research efforts. PMID:26501116

  4. Genomewide linkage scan reveals novel loci modifying age of onset of Huntington's disease in the Venezuelan HD kindreds.

    PubMed

    Gayán, Javier; Brocklebank, Denise; Andresen, J Michael; Alkorta-Aranburu, Gorka; Zameel Cader, M; Roberts, Simone A; Cherny, Stacey S; Wexler, Nancy S; Cardon, Lon R; Housman, David E

    2008-07-01

    The age of onset of Huntington's disease (HD) is inversely correlated with the CAG length in the HD gene. The CAG repeat length accounts for 70% of the variability in HD age of onset. However, 90% of individuals worldwide with expanded alleles possess between 40 and 50 CAG repeat lengths in their HD gene. For these people, the size of their repeat only determines 44% of the variability in their age of onset. Once the effect of the CAG repeat has been accounted for, the residual variance in age of onset is a heritable trait. Targeted candidate gene studies and a genome scan have suggested some loci as potential modifiers of the age of onset of HD. We analyzed the large Venezuelan kindreds in which the HD gene was originally identified. These kindreds offer greater analytic power than standard sib-pair designs. We developed novel pedigree-member selection procedures to maximize power. Using a 5,858-single-nucleotide-polymorphism marker panel, we performed a genomewide linkage analysis. We discovered two novel loci on chromosome 2. Chromosome 2p25 (logarithm of the odds ratio (LOD)=4.29) and 2q35 (LOD=3.39) may contain genes that modify age of onset. A third linkage peak on chromosome 6q22 (LOD=2.48) may confirm the most promising locus from a previous genome scan. Two other candidate loci are suggestive on chromosome 5 (LOD=3.31 at 5p14 and LOD=3.14 at 5q32). All these regions harbor candidate genes that are potential HD modifier genes. Finding these modifier genes can reveal accessible and promising new therapeutic pathways and targets to ameliorate and cure HD.

  5. Development of human antibody fragments using antibody phage display for the detection and diagnosis of Venezuelan equine encephalitis virus (VEEV)

    PubMed Central

    Kirsch, Martina Inga; Hülseweh, Birgit; Nacke, Christoph; Rülker, Torsten; Schirrmann, Thomas; Marschall, Hans-Jürgen; Hust, Michael; Dübel, Stefan

    2008-01-01

    Background Venezuelan equine encephalitis virus (VEEV) belongs to the Alphavirus group. Several species of this family are also pathogenic to humans and are recognized as potential agents of biological warfare and terrorism. The objective of this work was the generation of recombinant antibodies for the detection of VEEV after a potential bioterrorism assault or an natural outbreak of VEEV. Results In this work, human anti-VEEV single chain Fragments variable (scFv) were isolated for the first time from a human naïve antibody gene library using optimized selection processes. In total eleven different scFvs were identified and their immunological specificity was assessed. The specific detection of the VEEV strains TC83, H12/93 and 230 by the selected antibody fragments was proved. Active as well as formalin inactivated virus particles were recognized by the selected antibody fragments which could be also used for Western blot analysis of VEEV proteins and immunohistochemistry of VEEV infected cells. The anti-VEEV scFv phage clones did not show any cross-reactivity with Alphavirus species of the Western equine encephalitis virus (WEEV) and Eastern equine encephalitis virus (EEEV) antigenic complex, nor did they react with Chikungunya virus (CHIKV), if they were used as detection reagent. Conclusion For the first time, this study describes the selection of antibodies against a human pathogenic virus from a human naïve scFv antibody gene library using complete, active virus particles as antigen. The broad and sensitive applicability of scFv-presenting phage for the immunological detection and diagnosis of Alphavirus species was demonstrated. The selected antibody fragments will improve the fast identification of VEEV in case of a biological warfare or terroristic attack or a natural outbreak. PMID:18764933

  6. Repeated emergence of epidemic/epizootic Venezuelan equine encephalitis from a single genotype of enzootic subtype ID virus.

    PubMed Central

    Powers, A M; Oberste, M S; Brault, A C; Rico-Hesse, R; Schmura, S M; Smith, J F; Kang, W; Sweeney, W P; Weaver, S C

    1997-01-01

    Venezuelan equine encephalitis (VEE) epidemics and equine epizootics occurred periodically in the Americas from the 1920s until the early 1970s, when the causative viruses, subtypes IAB and IC, were postulated to have become extinct. Recent outbreaks in Columbia and Venezuela have renewed interest in the source of epidemic/epizootic viruses and their mechanism of interepizootic maintenance. We performed phylogenetic analyses of VEE virus isolates spanning the entire temporal and geographic range of strains available, using 857-nucleotide reverse transcription-PCR products including the E3 and E2 genes. Analyses indicated that epidemic/epizootic viruses are closely related to four distinct, enzootic subtype ID-like lineages. One of these lineages, which occurs in Columbia, Peru, and Venezuela, also included all of the epidemic/epizootic isolates; the remaining three ID-like lineages, which occur in Panama, Peru, Florida, coastal Ecuador, and southwestern Columbia, were apparently not associated with epizootic VEE emergence. Within the Columbia/Peru/Venezuela lineage, three distinct monophyletic groups of epidemic/epizootic viruses were delineated, indicating that VEE emergence has occurred independently at least three times (convergent evolution). Representative, complete E2 amino acid sequences were compared to identify potential determinants of equine virulence and epizootic emergence. Amino acids implicated previously in laboratory mouse attenuation generally did not vary among the natural isolates that we examined, indicating that they probably are not involved in equine virulence changes associated with VEE emergence. Most informative amino acids correlated with phylogenetic relationships rather than phenotypic characteristics, suggesting that VEE emergence has resulted from several distinct combinations of mutations that generate viruses with similar antigenic and equine virulence phenotypes. PMID:9261393

  7. Prediction of extreme floods in the eastern Central Andes based on a complex networks approach

    NASA Astrophysics Data System (ADS)

    Boers, N.; Bookhagen, B.; Barbosa, H. M. J.; Marwan, N.; Kurths, J.; Marengo, J. A.

    2014-10-01

    Changing climatic conditions have led to a significant increase in the magnitude and frequency of extreme rainfall events in the Central Andes of South America. These events are spatially extensive and often result in substantial natural hazards for population, economy and ecology. Here we develop a general framework to predict extreme events by introducing the concept of network divergence on directed networks derived from a non-linear synchronization measure. We apply our method to real-time satellite-derived rainfall data and predict more than 60% (90% during El Niño conditions) of rainfall events above the 99th percentile in the Central Andes. In addition to the societal benefits of predicting natural hazards, our study reveals a linkage between polar and tropical regimes as the responsible mechanism: the interplay of northward migrating frontal systems and a low-level wind channel from the western Amazon to the subtropics.

  8. Lower bound on the amount of crustal shortening in the central Bolivia Andes

    SciTech Connect

    Sheffels, B.M. )

    1990-09-01

    Balanced cross sections across the Cordillera Oriental and Subandean zone of the central Bolivian Andes indicate that crustal shortening probably has played the dominant role in orogeny in this convergent margin setting. A minimum amount of shortening, 210 km, is documented, which can account for two-thirds of the present-day crustal cross-sectional area along a transect spanning the entire mountain range. Substantial crustal shortening may also require loss of the lower lithosphere to the asthenosphere. A large, minimum amount of crustal shortening in the Bolivian Andes shows, contrary to common assumptions about orogeny, that (1) magmatic addition may be volumetrically less important in orogeny in Andean-type margins and (2) crustal shortening is not uniquely associated with continental or island-arc collision.

  9. Illicit crops and armed conflict as constraints on biodiversity conservation in the Andes region.

    PubMed

    Fjeldså, Jon; Alvarez, María D; Lazcano, Juan Mario; León, Blanca

    2005-05-01

    Coca, once grown for local consumption in the Andes, is now produced for external markets, often in areas with armed conflict. Internationally financed eradication campaigns force traffickers and growers to constantly relocate, making drug-related activities a principal cause of forest loss. The impact on biodiversity is known only in general terms, and this article presents the first regional analysis to identify areas of special concern, using bird data as proxy. The aim of conserving all species may be significantly constrained in the Santa Marta and Perijá mountains, Darién, some parts of the Central Andes in Colombia, and between the middle Marañón and middle Huallaga valleys in Peru. Solutions to the problem must address the root causes: international drug markets, long-lasting armed conflict, and lack of alternative income for the rural poor.

  10. Illicit crops and armed conflict as constraints on biodiversity conservation in the Andes region.

    PubMed

    Fjeldså, Jon; Alvarez, María D; Lazcano, Juan Mario; León, Blanca

    2005-05-01

    Coca, once grown for local consumption in the Andes, is now produced for external markets, often in areas with armed conflict. Internationally financed eradication campaigns force traffickers and growers to constantly relocate, making drug-related activities a principal cause of forest loss. The impact on biodiversity is known only in general terms, and this article presents the first regional analysis to identify areas of special concern, using bird data as proxy. The aim of conserving all species may be significantly constrained in the Santa Marta and Perijá mountains, Darién, some parts of the Central Andes in Colombia, and between the middle Marañón and middle Huallaga valleys in Peru. Solutions to the problem must address the root causes: international drug markets, long-lasting armed conflict, and lack of alternative income for the rural poor. PMID:16042278

  11. Interseismic Rates From the CTO cGPS Andes and Nepal Networks

    NASA Astrophysics Data System (ADS)

    Genrich, J. F.; Galetzka, J.; Chowdhury, F.; Avouac, J.; Simons, M.; Barrientos, S. E.; Comte, D.; Norabuena, E. O.; Sapkota, S. N.

    2009-12-01

    To study crustal deformation at converging plate margins the Caltech Tectonics Observatory (CTO), together with partner institutions in the host countries, operates continuously observing GPS stations in the central Andes (northern Chile and southern Peru) and in Nepal. The currently 20-site Andes network was established in 2005 with 7 stations. Efforts are underway to provide data streaming links at near real time for the majority of sites. The Nepal network started with 10 sites in 2004 and has been expanded to 23 sites in the last couple of years. Dual frequency code and phase data from all sites are processed with the GAMIT/GLOBK processing package. Reliable interseismic velocities are now available for the majority of sites. Network metadata, rinex data files, processed time series and velocity estimates can be found online thru links at the CTO website: tectonics.caltech.edu.

  12. Foreland shortening and crustal balancing in the Andes at 30°S latitude

    NASA Astrophysics Data System (ADS)

    Allmendinger, R. W.; Figueroa, D.; Synder, D.; Beer, J.; Mpodozis, C.; Isaacks, B. L.

    1990-08-01

    Excellent surface exposures, known Benioff zone geometry, a dynamic morphology, and the availability of industry seismic reflection data all make the Andes at 30°S an excellent transect for investigating crustal-scale balanced sections. 150-170 km of horizontal shortening has occurred in three major belts located between the trench and the foreland. The thin-skinned, east-verging Precordillera of western Argentina accounts for 60-75% of the total shortening and formed mostly since major volcanism ceased at ˜10 Ma. Industry seismic reflection data show that the décollement of the Precordillera belt is located anomalously deep at ˜15 km. The belt is dominated by fault propagation folds and contains several prominent out-of-sequence thrust faults. Seismic stratigraphie analysis shows that Miocene strata in the Iglesia Valley, located between the Precordillera and the crest of the Andes, accumulated in a piggy-back basin. Onlap relations on the western side indicate that the High Cordillera was uplifted as a major fault bend fold over a buried ramp. Thrusting in the two western belts, both in the High Cordillera of Chile, formed during the waning stages of arc volcanism, 11-16 Ma. and account for 25-40% of the shortening. The observed shortening is probably greater than can be accounted for with reasonable crustal thicknesses, indicating the possibility of continental truncation or erosion along the plate margin or an anomalously thick root held down by the nearly flat subducted Nazca Plate. Our preferred crustal geometry puts the ramp between upper and lower crustal deformation west of the high topography, requiring crustal scale tectonic wedging to thicken the crust beneath the crest of the Andes. This non-unique model provides a simple explanation of the first order morphology of the Andes at this latitude.

  13. Human impacts on headwater fluvial systems in the northern and central Andes

    NASA Astrophysics Data System (ADS)

    Harden, Carol P.

    2006-09-01

    South America delivers more freshwater runoff to the ocean per km 2 land area than any other continent, and much of that water enters the fluvial system from headwaters in the Andes Mountains. This paper reviews ways in which human occupation of high mountain landscapes in the Andes have affected the delivery of water and sediment to headwater river channels at local to regional scales for millennia, and provides special focus on the vulnerability of páramo soils to human impact. People have intentionally altered the fluvial system by damming rivers at a few strategic locations, and more widely by withdrawing surface water, primarily for irrigation. Unintended changes brought about by human activities are even more widespread and include forest clearance, agriculture, grazing, road construction, and urbanization, which increase rates of rainfall runoff and accelerate processes of water erosion. Some excavations deliver more sediment to river channels by destabilizing slopes and triggering processes of mass-movement. The northern and central Andes are more affected by human activity than most high mountain regions. The wetter northern Andes are also unusual for the very high water retention characteristics of páramo (high elevation grass and shrub) soils, which cover most of the land above 3000 m. Páramo soils are important regulators of headwater hydrology, but human activities that promote vegetation loss and drying cause them to lose water storage capacity. New data from a case study in southern Ecuador show very low bulk densities (median 0.26 g cm - 3 ), high organic matter contents (median 43%), and high water-holding capacities (12% to 86% volumetrically). These data document wetter soils under grass than under tree cover. Effects of human activity on the fluvial system are evident at local scales, but difficult to discern at broader scales in the regional context of geomorphic adjustment to tectonic and volcanic processes.

  14. Two new species of Siphocampylus (Campanulaceae, Lobelioideae) from the Central Andes

    PubMed Central

    Lagomarsino, Laura P.; Santamaría-Aguilar, Daniel

    2016-01-01

    Abstract Two species of Siphocampylus (Campanulaceae: Lobelioideae) from the Central Andes of Peru and Bolivia are described, illustrated, and discussed with reference to related species. One species, Siphocampylus antonellii, is endemic to high elevation grasslands of Calca, Peru, while the second, Siphocampylus siberiensis, is endemic to cloud forests of Cochabamba, Bolivia. Both species are robust shrubs that produce tubular pink flowers that are likely pollinated by hummingbirds. PMID:26884710

  15. Climate in the Western Cordillera of the Central Andes over the last 4300 years

    NASA Astrophysics Data System (ADS)

    Engel, Zbyněk; Skrzypek, Grzegorz; Chuman, Tomáš; Šefrna, Luděk; Mihaljevič, Martin

    2014-09-01

    The Distichia peat core obtained in the Carhuasanta valley near Nevado Mismi, Cordillera Chila, provides information on climatic and environmental conditions over the last ˜4300 years. The relative changes in the stable carbon isotope composition of plant remains preserved in the core reflect major temperature fluctuations in the Western Cordillera of the southern Peruvian Andes. These temperature variations can be additionally linked with the changes in precipitation patterns by analysing C% and C/N ratio in the core. Relatively warm and moist conditions prevailed from 4280 to 3040 cal. yrs BP (BC 2330-1090) with a short colder dry episode around 3850 cal. yrs BP (BC 1900). The most prominent climate changes recorded in the peat occurred between 3040 and 2750 cal. yrs BP (BC 1090-800) when the initial warming turned to a rapid cooling to temperatures at least 2 °C lower than the mean for the Late Holocene. Initially drier conditions within this event turned to a short wet phase after 2780 cal. yrs BP (BC 830) when the temperature increased again. This event coincides with significant changes in peat and ice core records in the Central Andes matching the timing of the global climate event around 2.8 cal. ka BP. Climatic conditions in the study area became relatively dry and stable after the event for about 800 years. Highly variable temperatures and humidity prevailed during the last 2000 years when an extended warm and relatively humid period occurred between 640 and 155 cal. yrs BP (AD 1310-1795) followed by predominantly colder and drier conditions. The established δ13C peat record represents the first continuous proxy for the temperature in the southern Peruvian Andes dated by the AMS 14C. Distichia peat is wide spread in the Andes and the proposed approach can be applied elsewhere in high altitudes, where no other traditional climate proxies are available.

  16. The Pampean flat-slab of the Central Andes

    NASA Astrophysics Data System (ADS)

    Ramos, Victor A.; Cristallini, E. O.; Pérez, Daniel J.

    2002-04-01

    Late Cenozoic Andean deformation in the Pampean segment of Argentina and Chile (27°00'-33°30'S) provides an exceptional opportunity to study the orogenic effects of flat subduction in an active convergent margin. At these latitudes, constraints derived from oceanic geomorphic structures indicate that collision of the Juan Fernandez Ridge in the Nazca plate with the Chilean trench propagated from north to south from ca. 18 to ca. 11 Ma. In this region, Cenozoic tectonics have resulted in the development of the Principal and Frontal Cordilleras, the Cuyo Precordillera, and the associated Sierras Pampeanas in the eastward foreland region. The analyses of different structural transects across the Sierras Pampeanas between 27 and 33°S latitudes show a southward diachronic beginning of basement block uplift from 7.6 to 6 Ma in the Sierra de Aconquija (27°S), 4.5 to 4.19 Ma at Sierra de Famatina (29°S), 5.5 to 4.7 Ma at Sierra de Pocho (31°S), and ca. 2.6 Ma at Sierra de San Luis (33°S). Uplift times are constrained by the age of synorogenic deposits, fission-track data on apatite, and hydrogen isotopes in alunite, where available. These time constraints are compared with the migration and expansion of the magmatic activity into the foreland. The relation of these two data sets shows a striking coincidence, after a residence time of approximately 4-2.6 Ma, between magmatic activity and failure of the crust that resulted in basement block uplift. Thermal weakening of the crust associated with eastward migration of arc magmatism acted to elevate brittle-ductile subsurface décollments, thus leading to thick-skinned basement uplift of the Sierras Pampeanas. The evolution of the Sierras Pampeanas is linked to that of the main Andes at 33°S latitude. The main deformation phases and uplift of the thin- and thick-skinned fold and thrust belts of Principal Cordillera occurred between 20 and 8.6 Ma. Arc volcanism migrated eastward at this latitude between 16 and 15.8 Ma

  17. Airborne Imaging Spectroscopy of Forest Canopy Chemistry in the Andes-Amazon Corridor

    NASA Astrophysics Data System (ADS)

    Martin, R.; Anderson, C.; Knapp, D. E.; Asner, G. P.

    2013-12-01

    The Andes-Amazon corridor is one of the most biologically diverse regions on Earth. Elevation gradients provide opportunities to explore the underlying sources and environmental controls on functional diversity of the forest canopy, however plot-based studies have proven highly variable. We used airborne imaging spectroscopy from the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS) to quantify changes canopy functional traits in a series of eleven 25-ha landscapes distributed along a 3300 m elevation gradient from lowland Amazonia to treeline in the Peruvian Andes. Each landscape encompassed a 1 ha field plot in which all trees reaching the canopy were climbed and leaves were sampled for 20 chemical traits. We used partial least squares regression to relate plot-level chemical values with airborne spectroscopy from the 1 ha area. Sixteen chemical traits produced predictable relationships with the spectra and were used to generate maps of the 25 ha landscape. Ten chemical traits were significantly related to elevation at the 25 ha scale. These ten traits displayed 35% greater accuracy (R2) and precision (rmse) when evaluated at the 25 ha scale compared to values derived from tree climbing alone. The results indicate that high-fidelity imaging spectroscopy can be used as surrogate for laborious tree climbing and chemical assays to understand chemical diversity in Amazonian forests. Understanding how these chemicals vary among forest communities throughout the Andes-Amazon corridor will facilitate mapping of functional diversity and the response of canopies to climate change.

  18. Evolution into and out of the Andes: a Bayesian analysis of historical diversification in Thamnophilus antshrikes.

    PubMed

    Brumfield, Robb T; Edwards, Scott V

    2007-02-01

    The Andean uplift played important roles in the historical diversification of Neotropical organisms, both by producing new high-elevation habitats that could be colonized and by isolating organisms on either side of the mountains. Here, we present a molecular phylogeny of Thamnophlius antshrikes, a clade of 30 species whose collective distribution spans nearly the entirety of lowland habitats in tropical South America, the eastern slope foothills of the Andes, and the tepuis of northern South America. Our goal was to examine the role of the Andes in the diversification of lowland and foothill species. Using parsimony and Bayesian ancestral state reconstructions of a three-state distribution character (lowland-restricted, lowland-to-highland, highland-restricted), we found that the Andes were colonized twice independently and the tepuis once from lowland-restricted ancestors. Over the entire evolutionary history of Thamnophilus, the highest transition rates were between highland-restricted and lowland-to-highland distributions, with extremely low rates into and out of lowland-restricted distributions. This pattern suggests lowland-restricted distributions are limited not by physiological constraints, but by other forces, such as competition. These results highlight the need for additional comparative studies in elucidating processes associated with the colonization of high-elevation habitats and the differentiation of populations within them.

  19. Miocene orographic uplift forces rapid hydrological change in the southern central Andes

    PubMed Central

    Rohrmann, Alexander; Sachse, Dirk; Mulch, Andreas; Pingel, Heiko; Tofelde, Stefanie; Alonso, Ricardo N.; Strecker, Manfred R.

    2016-01-01

    Rainfall in the central Andes associated with the South American Monsoon and the South American Low-Level Jet results from orographic effects on atmospheric circulation exerted by the Andean Plateau and the Eastern Cordillera. However, despite its importance for South American climate, no reliable records exist that allow decoding the evolution of thresholds and interactions between Andean topography and atmospheric circulation, especially regarding the onset of humid conditions in the inherently dry southern central Andes. Here, we employ multi-proxy isotope data of lipid biomarkers, pedogenic carbonates and volcanic glass from the Eastern Cordillera of NW Argentina and present the first long-term evapotranspiration record. We find that regional eco-hydrology and vegetation changes are associated with initiation of moisture transport via the South American Low-Level Jet at 7.6 Ma, and subsequent lateral growth of the orogen at 6.5 Ma. Our results highlight that topographically induced changes in atmospheric circulation patterns, not global climate change, were responsible for late Miocene environmental change in this part of the southern hemisphere. This suggests that mountain building over time fundamentally controlled habitat evolution along the central Andes. PMID:27767043

  20. A reevaluation of the evidence for a Younger Dryas climatic reversal in the tropical Andes

    NASA Astrophysics Data System (ADS)

    Heine, Jan T.

    A review of the evidence for a Younger Dryas-equivalent climatic reversal in the tropical Andes shows that a number of hypotheses need to be reassessed. Assumptions of the El Abra cold and humid phase in Colombia are compromised by insufficient dating control. Periods of glacier advance in Peru and Bolivia lack sufficient dating control to be correlated with the European Younger Dryas. Only glaciers on the Quelccaya Ice Cap in Peru may have advanced shortly before the onset of the European climatic reversal, but even there a correlation is questionable. A late-glacial advance in the Chimborazo area in Ecuador is considerably older than previously suggested. The same glacier advance has been dated to earlier than 12,000 BP in other areas of Ecuador. The emerging picture suggests two phases of glacier advances in the tropical Andes: 13,000-12,000 BP and 9000-10,000 BP. Both may have been caused by increasing precipitation. Unequivocal evidence for a cold Younger Dryas event in the tropical Andes has yet to emerge.

  1. The Irish potato famine pathogen Phytophthora infestans originated in central Mexico rather than the Andes

    PubMed Central

    Goss, Erica M.; Tabima, Javier F.; Cooke, David E. L.; Restrepo, Silvia; Fry, William E.; Forbes, Gregory A.; Fieland, Valerie J.; Cardenas, Martha; Grünwald, Niklaus J.

    2014-01-01

    Phytophthora infestans is a destructive plant pathogen best known for causing the disease that triggered the Irish potato famine and remains the most costly potato pathogen to manage worldwide. Identification of P. infestan’s elusive center of origin is critical to understanding the mechanisms of repeated global emergence of this pathogen. There are two competing theories, placing the origin in either South America or in central Mexico, both of which are centers of diversity of Solanum host plants. To test these competing hypotheses, we conducted detailed phylogeographic and approximate Bayesian computation analyses, which are suitable approaches to unraveling complex demographic histories. Our analyses used microsatellite markers and sequences of four nuclear genes sampled from populations in the Andes, Mexico, and elsewhere. To infer the ancestral state, we included the closest known relatives Phytophthora phaseoli, Phytophthora mirabilis, and Phytophthora ipomoeae, as well as the interspecific hybrid Phytophthora andina. We did not find support for an Andean origin of P. infestans; rather, the sequence data suggest a Mexican origin. Our findings support the hypothesis that populations found in the Andes are descendants of the Mexican populations and reconcile previous findings of ancestral variation in the Andes. Although centers of origin are well documented as centers of evolution and diversity for numerous crop plants, the number of plant pathogens with a known geographic origin are limited. This work has important implications for our understanding of the coevolution of hosts and pathogens, as well as the harnessing of plant disease resistance to manage late blight. PMID:24889615

  2. Tertiary tectonics of the sub-Andean region of the North Patagonian Andes, southern central Andes of Argentina (41 42°30‧S)

    NASA Astrophysics Data System (ADS)

    Giacosa, Raúl E.; Afonso, Juan C.; Heredia C., Nemesio; Paredes, José

    2005-12-01

    The sub-Andean region of the North Patagonian Andes is located between the north Patagonian foreland and the highest elevations of the Andean Cordillera. Its Tertiary contractional structure, active since the upper Late Oligocene and through the upper Late Miocene, corresponds to the external sector of the North Patagonian Andes fold-and-thrust belt, which is characterized by east-vergent thrusts that affect stratified Cenozoic rocks. The units involved in the deformation correspond to El Maitén Oligocene volcanic belt, deformed between east-vergent thrusts and backthrusts, and Oligocene-Miocene sedimentary rocks of the Ñirihuau-Collón Curá Basin. The northern sector of the basin was structured as a thin-skinned fold belt that comprises the Ñirihuau fold belt and a frontal sedimentary wedge. To the south, sedimentary depocenters are confined between medium- to high-angle reverse faults with evidence of basement structural control. In both cases, the general tectonosedimentary framework shows the youngest units toward the east, in agreement with the advance of the orogenic wedge. Most of the Ñirihuau-Collón Curá Basin infill fits a foreland basin system model. Some sectors of the basin show evidence of structural control by normal faults in the initial sedimentation stages. This early extensional regime might be associated with late phases of Oligocene volcanism. Extensional structures probably were partially reactivated during the upper Late Oligocene, as suggested by seismic data.

  3. A ~13,000 year history of glacial variability in the tropical Andes recorded in lake sediments from the Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Stansell, N. D.; Rodbell, D. T.; Mark, B. G.; Sedlak, C. M.

    2012-04-01

    Pro-glacial lake sediments from Peru contain continuous records of climatic variability spanning the Holocene. Here we present results from multiple alpine lake basins along an east-west transect through the Peruvian Andes that contain high-resolution records of clastic sediment variability for the last ~13,000 years. Radiocarbon-dated sediment cores were measured by scanning X-ray Fluorescence, and for magnetic susceptibility, carbon content, biogenic silica and calcium carbonate concentrations. Samples of bedrock and sediments from glacial moraines in the watersheds were analyzed using ICP-MS in order to fingerprint and trace the source of glacial sediments deposited in the lakes. Preliminary results indicate that glaciers retreated after after ~13,000 cal yr BP and remained less extensive during the remaining late Glacial Stage and early Holocene. Gradually increasing clastic sediments through most of the remaining Holocene indicate that glaciers became progressively larger, or more erosive, during the last ~10,000 years. This overall Holocene trend of increasing glacier extent was interrupted by a pronounced decrease in clastic sediments from ~2500 to 550 cal yr BP, and glaciers then advanced again during the Little Ice Age (~550 to 70 cal yr BP). Periods of ice advance in the Peruvian Andes generally correspond to times of increased moisture-balance and lower temperatures that are recorded in other regional, terrestrial proxy records.

  4. Purification, crystallization and X-ray diffraction analysis of the C-terminal protease domain of Venezuelan equine encephalitis virus nsP2

    SciTech Connect

    Russo, Andrew T.; Watowich, Stanley J.

    2006-06-01

    The C-terminal protease domain of Venezuelan equine encephalitis virus (VEEV) nsP2 has been overexpressed in E. coli, purified and successfully crystallized. Native crystals diffract to beyond 2.5 Å resolution and isomorphous heavy-atom derivatives suitable for phase analysis have been identified. The C-terminal region of Venezuelan equine encephalitis virus (VEEV) nsP2 is responsible for proteolytic processing of the VEEV polyprotein replication complex. This action regulates the activity of the replication complex and is essential for viral replication, thus making nsP2 a very attractive target for development of VEEV therapeutics. The 338-amino-acid C-terminal region of VEEV nsP2 has been overexpressed in Escherichia coli, purified and crystallized. Crystals diffract to beyond 2.5 Å resolution and belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}. Isomorphous heavy-atom derivatives suitable for phase analysis have been obtained and work on building a complete structural model is under way.

  5. Imaging the transition from flat to normal subduction: variations in the structure of the Nazca slab and upper mantle under southern Peru and northwestern Bolivia

    NASA Astrophysics Data System (ADS)

    Scire, Alissa; Zandt, George; Beck, Susan; Long, Maureen; Wagner, Lara; Minaya, Estela; Tavera, Hernando

    2016-01-01

    Two arrays of broad-band seismic stations were deployed in the north central Andes between 8° and 21°S, the CAUGHT array over the normally subducting slab in northwestern Bolivia and southern Peru, and the PULSE array over the southern part of the Peruvian flat slab where the Nazca Ridge is subducting under South America. We apply finite frequency teleseismic P- and S-wave tomography to data from these arrays to investigate the subducting Nazca plate and the surrounding mantle in this region where the subduction angle changes from flat north of 14°S to normally dipping in the south. We present new constraints on the location and geometry of the Nazca slab under southern Peru and northwestern Bolivia from 95 to 660 km depth. Our tomographic images show that the Peruvian flat slab extends further inland than previously proposed along the projection of the Nazca Ridge. Once the slab re-steepens inboard of the flat slab region, the Nazca slab dips very steeply (˜70°) from about 150 km depth to 410 km depth. Below this the slab thickens and deforms in the mantle transition zone. We tentatively propose a ridge-parallel slab tear along the north edge of the Nazca Ridge between 130 and 350 km depth based on the offset between the slab anomaly north of the ridge and the location of the re-steepened Nazca slab inboard of the flat slab region, although additional work is needed to confirm the existence of this feature. The subslab mantle directly below the inboard projection of the Nazca Ridge is characterized by a prominent low-velocity anomaly. South of the Peruvian flat slab, fast anomalies are imaged in an area confined to the Eastern Cordillera and bounded to the east by well-resolved low-velocity anomalies. These low-velocity anomalies at depths greater than 100 km suggest that thick mantle lithosphere associated with underthrusting of cratonic crust from the east is not present. In northwestern Bolivia a vertically elongated fast anomaly under the Subandean Zone

  6. Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the Southern Andes

    USGS Publications Warehouse

    Futa, K.; Stern, C.R.

    1988-01-01

    Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-46??S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-54??S) range for 87Sr 86Sr from 0.70280 to 0.70591 and for 143Nd 144Nd from 0.51314 to 0.51255. The ranges are significantly greater than previously reported from the southern Andes but are different from the isotopic compositions of volcanoes in the central and northern Andes. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr 86Sr, 143Nd 144Nd, La Yb, Ba La, and Hf Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 35??S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 33?? and 34??S, basaltic andesites and andesites have higher 87Sr 86Sr, Rb Cs, and Hf Lu, and lower 143Nd 144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (54??S) has Sr and Nd isotopic compositions and K Rb and Ba La similar to MORB. The high La Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba La, and 87Sr 86Sr and decrease in MgO, Sr, K Rb, Rb Cs, and 143Nd 144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra

  7. Facing unprecedented drying of the Central Andes? Precipitation variability over the period AD 1000-2100

    NASA Astrophysics Data System (ADS)

    Neukom, Raphael; Rohrer, Mario; Calanca, Pierluigi; Salzmann, Nadine; Huggel, Christian; Acuña, Delia; Christie, Duncan A.; Morales, Mariano S.

    2015-08-01

    Projected future trends in water availability are associated with large uncertainties in many regions of the globe. In mountain areas with complex topography, climate models have often limited capabilities to adequately simulate the precipitation variability on small spatial scales. Also, their validation is hampered by typically very low station density. In the Central Andes of South America, a semi-arid high-mountain region with strong seasonality, zonal wind in the upper troposphere is a good proxy for interannual precipitation variability. Here, we combine instrumental measurements, reanalysis and paleoclimate data, and a 57-member ensemble of CMIP5 model simulations to assess changes in Central Andes precipitation over the period AD 1000-2100. This new database allows us to put future projections of precipitation into a previously missing multi-centennial and pre-industrial context. Our results confirm the relationship between regional summer precipitation and 200 hPa zonal wind in the Central Andes, with stronger Westerly winds leading to decreased precipitation. The period of instrumental coverage (1965-2010) is slightly dryer compared to pre-industrial times as represented by control simulations, simulations from the past Millennium, ice core data from Quelccaya ice cap and a tree-ring based precipitation reconstruction. The model ensemble identifies a clear reduction in precipitation already in the early 21st century: the 10 year running mean model uncertainty range (ensemble 16-84% spread) is continuously above the pre-industrial mean after AD 2023 (AD 2028) until the end of the 21st century in the RCP2.6 (RCP8.5) emission scenario. Average precipitation over AD 2071-2100 is outside the range of natural pre-industrial variability in 47 of the 57 model simulations for both emission scenarios. The ensemble median fraction of dry years (defined by the 5th percentile in pre-industrial conditions) is projected to increase by a factor of 4 until 2071-2100 in

  8. Developing services for climate impact and adaptation baseline information and methodologies for the Andes

    NASA Astrophysics Data System (ADS)

    Huggel, C.

    2012-04-01

    Impacts of climate change are observed and projected across a range of ecosystems and economic sectors, and mountain regions thereby rank among the hotspots of climate change. The Andes are considered particularly vulnerable to climate change, not only due to fragile ecosystems but also due to the high vulnerability of the population. Natural resources such as water systems play a critical role and are observed and projected to be seriously affected. Adaptation to climate change impacts is therefore crucial to contain the negative effects on the population. Adaptation projects require information on the climate and affected socio-environmental systems. There is, however, generally a lack of methodological guidelines how to generate the necessary scientific information and how to communicate to implementing governmental and non-governmental institutions. This is particularly important in view of the international funds for adaptation such as the Green Climate Fund established and set into process at the UNFCCC Conferences of the Parties in Cancun 2010 and Durban 2011. To facilitate this process international and regional organizations (World Bank and Andean Community) and a consortium of research institutions have joined forces to develop and define comprehensive methodologies for baseline and climate change impact assessments for the Andes, with an application potential to other mountain regions (AndesPlus project). Considered are the climatological baseline of a region, and the assessment of trends based on ground meteorological stations, reanalysis data, and satellite information. A challenge is the scarcity of climate information in the Andes, and the complex climatology of the mountain terrain. A climate data platform has been developed for the southern Peruvian Andes and is a key element for climate data service and exchange. Water resources are among the key livelihood components for the Andean population, and local and national economy, in particular for

  9. Heat flow from eastern Panama and northwestern Colombia

    USGS Publications Warehouse

    Sass, J.H.; Munroe, R.J.; Moses, T.H.

    1974-01-01

    Heat flows were determined at 12 sites in four distinct areas between longitude 77?? and 80??W in eastern Panama and northwestern Colombia. Evidently, most of the region is underlain by mafic oceanic crust so that the crustal radiogenic component of heat flow is very small (??? 0.1 ??cal cm-2 sec-1). Low heat-flow values (??? 0.7 ??cal cm-2 sec-1) in northwestern Colombia may reflect thermal transients associated with shallow subduction. The normal values (??? 1) at about 78??W are consistent with the mean heat flow from the western Caribbean and the Gulf of Mexico. At 80??W, a fairly high value of 1.8 may define the easterly limit of thermal transients due to Cenozoic volcanic activity in Central America. ?? 1974.

  10. Geology of the lower Yellow Creek Area, Northwestern Colorado

    SciTech Connect

    Hail, W.J.

    1990-01-01

    The lower Yellow Creek area is located in Rio Blanco and Moffat Counties of northwestern Colorado, about midway between the towns of Rangely and Meeker. The study area is in the northwestern part of the Piceance Creek basin, a very deep structural and sedimentary basin that formed during the Laramide orogeny. Potentially important resources in the area are oil shale and related minerals, oil and gas, coal, and uranium. Topics discussed in the report include: Stratigraphy (Subsurface rocks, Cretaceous rocks, Tertiary rocks, and Quaternary deposits); Structure (Midland anticline, graben at Pinyon Ridge, and Crooked Wash syncline, Folds and faults in the vicinity of the White River, Red Wash syncline and central graben zone, Yellow Creek anticlinal nose); Economic geology (Oil shale and associated minerals, Coal, Oil and gas, Uranium, Gravel).

  11. Northwestern University Facility for Clean Catalytic Process Research

    SciTech Connect

    Marks, Tobin Jay

    2013-05-08

    Northwestern University with DOE support created a Facility for Clean Catalytic Process Research. This facility is designed to further strengthen our already strong catalysis research capabilities and thus to address these National challenges. Thus, state-of-the art instrumentation and experimentation facility was commissioned to add far greater breadth, depth, and throughput to our ability to invent, test, and understand catalysts and catalytic processes, hence to improve them via knowledge-based design and evaluation approaches.

  12. Primary health care in northwestern Somalia: a case study.

    PubMed

    Bentley, C

    1989-01-01

    This paper examines the problem of initiating health care programmes in areas where there is no effective infrastructure. The problem is examined using Northwestern Somalia as a case study. The project focussed on the establishment of well-trained and well-supported CHWs at the community level. Many of these communities are (semi-)nomadic. The roles of middle-level management staff, community leaders and committees, CHW remuneration and health effects of the project are discussed. PMID:2717966

  13. Food habits of pumas in northwestern Sonora, Mexico

    USGS Publications Warehouse

    Rosas-Rosas, O. C.; Valdez, R.; Bender, L.C.; Daniel, D.

    2003-01-01

    It is questionable whether food-habits studies of pumas conducted in the southwestern United States can be extrapolated to northwestern Mexico, because of differences in management, distribution, and abundance of wildlife. We determined food habits of pumas (Puma concolor) in the Sonoran Desert of northwestern Sonora, Mexico. Based on studies in the western United States, we hypothesized that desert mule deer (Odocoileus hemionus) were the major food source of pumas in Sonoran Desert habitats of Mexico. The study area supports populations of desert mule deer, white-tailed deer (Odocoileus virginianus), lagomorphs (Lepus spp. and Sylvilagus audubonii), collared peccary (Pecari tajacu), and the largest population (???300 individuals) of desert bighorn sheep (Ovis canadensis) in Sonora. Based on pugmark characteristics, we recorded 3 different adult resident pumas in approximately 90 km2. We analyzed 60 puma fecal samples collected September 1996-November 1998. Primary prey items based on frequency of occurrence and estimated biomass consumed were desert bighorn sheep (40% and 45%, respectively), lagomorphs (33%, 19%), deer (17%, 17%), and collared peccary (15%, 11%). The high percentage of desert bighorn sheep in puma diets may be due to high abundance relative to mule deer, which declined in number during our study. No differences were found in puma diets between seasons (??22=2.4526, P=0.2934). Fluctuations in mule deer populations in northwestern Sonora may influence prey selection by pumas.

  14. Infection by Ascaris lumbricoides and bronchial hyper reactivity: an outstanding association in Venezuelan school children from endemic areas.

    PubMed

    Hagel, I; Cabrera, M; Hurtado, M A; Sanchez, P; Puccio, F; Di Prisco, M C; Palenque, M

    2007-09-01

    Asthma and other respiratory diseases have increased in the last years among Venezuelan children from helminthic endemic areas where the infection by Ascaris lumbricoides has been associated to bronchial airway inflammation in parasitized individuals. The aim of this work was to investigate the possible associations between the development of bronchial hyper reactivity and the immune response against A. lumbricoides in urban and rural children. We evaluated 470 school children from rural and urban communities. Pulmonary function tests were performed and >or=20% PC(20) changes were considered as a positive diagnostic of bronchial hyper reactivity. The prevalence and intensity of A. lumbricoides infection was determined by faecal examination. Specific serum IgE levels using a modified ELISA and skin prick tests against A. lumbricoides and the common allergen Dermatophagoides pteronyssinus were done. The number of circulating lymphocyte sub populations was determined by flow cytometry analysis. In rural children, bronchial hyper reactivity was associated with increased specific levels of anti-A. lumbricoides IgE (p<0.0001) and skin test positivity for A. lumbricoides (p<0.0001). The percentage of FEV1 predictive values correlated inversely (p<0.0001) with anti-A. lumbricoides IgE levels. Elevated numbers of circulating CD3+CD4+ and CD20+CD23+ cells were found in rural children with bronchial hyper reactivity compared to their asymptomatic counterparts. They correlated positively with anti-A. lumbricoides IgE levels (p<0.005 and <0.0001, respectively). In contrast, in urban children, bronchial hyper reactivity was associated with elevated anti-D. pteronyssinus IgE levels (p=0. 0089), skin hyper reactivity towards this aero allergen (p=0.003) and to an increase in the number of CD3+CD8+ (p<0.0001). Our results suggest that the IgE response against A. lumbricoides infection may be involved in the development of bronchial hyper reactivity among rural children from endemic

  15. mRNA Capping by Venezuelan Equine Encephalitis Virus nsP1: Functional Characterization and Implications for Antiviral Research

    PubMed Central

    Li, Changqing; Guillén, Jaime; Rabah, Nadia; Blanjoie, Alexandre; Debart, Françoise; Vasseur, Jean-Jacques; Canard, Bruno; Decroly, Etienne

    2015-01-01

    ABSTRACT Alphaviruses are known to possess a unique viral mRNA capping mechanism involving the viral nonstructural protein nsP1. This enzyme harbors methyltransferase (MTase) and nsP1 guanylylation (GT) activities catalyzing the transfer of the methyl group from S-adenosylmethionine (AdoMet) to the N7 position of a GTP molecule followed by the formation of an m7GMP-nsP1 adduct. Subsequent transfer of m7GMP onto the 5′ end of the viral mRNA has not been demonstrated in vitro yet. Here we report the biochemical characterization of Venezuelan equine encephalitis virus (VEEV) nsP1. We have developed enzymatic assays uncoupling the different reactions steps catalyzed by nsP1. The MTase and GT reaction activities were followed using a nonhydrolyzable GTP (GIDP) substrate and an original Western blot assay using anti-m3G/m7G-cap monoclonal antibody, respectively. The GT reaction is stimulated by S-adenosyl-l-homocysteine (Ado-Hcy), the product of the preceding MTase reaction, and metallic ions. The covalent linking between nsP1 and m7GMP involves a phosphamide bond between the nucleotide and a histidine residue. Final guanylyltransfer onto RNA was observed for the first time with an alphavirus nsP1 using a 5′-diphosphate RNA oligonucleotide whose sequence corresponds to the 5′ end of the viral genome. Alanine scanning mutagenesis of residues H37, H45, D63, E118, Y285, D354, R365, N369, and N375 revealed their respective roles in MT and GT reactions. Finally, the inhibitory effects of sinefungin, aurintricarboxylic acid (ATA), and ribavirin triphosphate on MTase and capping reactions were investigated, providing possible avenues for antiviral research. IMPORTANCE Emergence or reemergence of alphaviruses represents a serious health concern, and the elucidation of their replication mechanisms is a prerequisite for the development of specific inhibitors targeting viral enzymes. In particular, alphaviruses are able, through an original reaction sequence, to add to their

  16. Changes in structure and composition of evergreen forests on an altitudinal gradient in the Venezuelan Guayana shield.

    PubMed

    Hernández, Lionel; Dezzeo, Nelda; Sanoja, Elio; Salazar, Leandro; Castellanos, Hernán

    2012-03-01

    There have been several ecological studies in forests of the Guayana Shield, but so far none had examined the changes in structure and composition of evergreen forests with altitude. This study describes and analyzes the structure, species composition and soil characteristics of forest stands at different altitudinal zones in Southeastern Venezuelan Guayana, in order to explain the patterns and the main factors that determine the structure and composition of evergreen forests along the altitudinal gradient. Inventories of 3 948 big (>10cm DBH) and 1 328 small (5-10cm DBH) woody stems were carried out in eleven plots, ranging from 0.1 to 1.0ha, along a 188km long transect with elevations between 290 and 1 395masl. It has been found that 1) hemiepihytes become more dominant and lianas reduce their dominance with increasing altitude and 2) the forest structure in the study area is size-dependent. Five families and 12 genera represented only 9% of the total number of families and genera, respectively, recorded troughout the gradient, but the two groups of taxa comprised more than 50% of the Importance Value (the sum of the relative density and the relative dominance) of all measured stems. Moreover, the results suggest that low species richness seems to be associated with the dominance of one or few species. Stand-level wood density (WD) of trees decreased significantly with increasing elevation. WD is an indicator of trees'life history strategy. Its decline suggests a change in the functional composition of the forest with increasing altitude. The Canonical Correspondence Analysis (CCA) indicated a distinction of the studied forests on the basis of their altitudinal levels and geographic location, and revealed different ecological responses by the forests, to environmental variables along the altitudinal gradient. The variation in species composition, in terms of basal area among stands, was controlled primarily by elevation and secondarily by rainfall and soil

  17. Seismicity, fault plane solutions, depth of faulting, and active tectonics of the Andes of Peru, Ecuador, and southern Colombia

    NASA Technical Reports Server (NTRS)

    Suarez, G.; Molnar, P.; Burchfiel, B. C.

    1983-01-01

    The long-period P waveforms observed for 17 earthquakes in the Peruvian Andes during 1963-1976 are compared with synthetic waveforms to obtain fault-plane solutions and focal depths. The morphological units of the Peruvian Andes are characterized: coastal plains, Cordillera Occidental, altiplano and central high plateau, Cordillera Oriental, and sub-Andes. The data base and analysis methodology are discussed, and the results are presented in tables, diagrams, graphs, maps, and photographs illustrating typical formations. Most of the earthquakes are shown to occur in the transition zone from the sub-Andes to the Cordillera Oriental under formations of about 1 km elevation at focal depths of 10-38 km. It is suggested that the sub-Andean earthquakes reflect hinterland deformation of a detached fold and thrust belt, perhaps like that which occurred in parts of the Canadian Rockies. From the total crustal shortening evident in Andean morphology and the shortening rate of the recent earthquakes it is estimated that the topography and crustal root of the Andes have been formed during the last 90-135 Myr.

  18. Late paleozoic tectonic amalgamation of northwestern China. Sedimentary record of the northern Tarim, northwestern Turpan, and southern Junggar basins

    SciTech Connect

    Carroll, A.R.; Graham, S.A.; Hendrix, M.S.; Ying, D.; Zhou, D.

    1995-05-01

    This study focuses on areas adjacent to the Tian Shan (shan is Chinese for mountains) in Xinjiang Uygur Autonomous Region, northwestern China, and provides new field data on Carboniferous and Permian outcrop exposures of sedimentary rocks of the southern Junggar, northwestern Turpan, and northern Tarim basins that bear directly on the history of late Paleozoic tectonic amalgamation. We present here a multifaceted sedimentary basin analysis, including sedimentary facies, paleocurrent, and sandstone provenance analyses, and reconstructions of late Paleozoic basin subsidence. These data provide a unique record not only of the basins themselves, but also of the evolution of the adjacent orogenic belts. This study is based on fieldwork during the summers of 1987, 1988, 1991, and 1992 by workers from Stanford University, the Chinese Academy of Geological Sciences, and the Xinjiang Bureau of Geology and Mineral Resources. Although reconnaissance in nature, the data presented here provide a basis for evaluating alternative hypotheses for the evolution of northwestern China and provide a starting point for more comprehensive future studies. 72 refs., 18 figs., 1 tab.

  19. A new species of Alopoglossus lizard (Squamata, Gymnophthalmidae) from the tropical Andes, with a molecular phylogeny of the genus.

    PubMed

    Torres-Carvajal, Omar; Lobos, Simón E

    2014-01-01

    We describe a new species of Alopoglossus from the Pacific slopes of the Andes in northern Ecuador based on morphological and molecular evidence. The new species differs most significantly from all other congeners in having a double longitudinal row of widened gular scales, lanceolate dorsal scales in transverse rows, 29-32 dorsal scales in a transverse row at midbody, and 4 longitudinal rows of ventrals at midbody. It is most similar in morphology to A. festae, the only species of Alopoglossus currently recognized in western Ecuador. We analyze the phylogenetic relationships among species of Alopoglossus based on the mitochondrial gene ND4. Cis-Andean [east of the Andes] and Trans-Andean [west of the Andes] species are nested in two separate clades, suggesting that the uplift of these mountains had an important effect in the diversification of Alopoglossus. In addition, we present an updated key to the species of Alopoglossus.

  20. A new species of Alopoglossus lizard (Squamata, Gymnophthalmidae) from the tropical Andes, with a molecular phylogeny of the genus

    PubMed Central

    Torres-Carvajal, Omar; Lobos, Simón E.

    2014-01-01

    Abstract We describe a new species of Alopoglossus from the Pacific slopes of the Andes in northern Ecuador based on morphological and molecular evidence. The new species differs most significantly from all other congeners in having a double longitudinal row of widened gular scales, lanceolate dorsal scales in transverse rows, 29–32 dorsal scales in a transverse row at midbody, and 4 longitudinal rows of ventrals at midbody. It is most similar in morphology to A. festae, the only species of Alopoglossus currently recognized in western Ecuador. We analyze the phylogenetic relationships among species of Alopoglossus based on the mitochondrial gene ND4. Cis-Andean [east of the Andes] and Trans-Andean [west of the Andes] species are nested in two separate clades, suggesting that the uplift of these mountains had an important effect in the diversification of Alopoglossus. In addition, we present an updated key to the species of Alopoglossus. PMID:24899852

  1. On the Nature of Severe Orographic Thunderstorms near the Andes in Subtropical South America

    NASA Astrophysics Data System (ADS)

    Rasmussen, Kristen Lani Emi

    Identifying common features and differences between the mechanisms producing extreme convection near major mountain ranges of the world is an essential step toward a general understanding of orographic precipitation on a global scale. The overarching objective of this dissertation is to understand and examine orographic convective processes in general, while specifically focusing on systems in the lee of the Andes Mountains. Diagnosing the key ingredients necessary for generating high impact weather near extreme topography is crucial to our understanding of orographic precipitating systems. An investigation of the most intense storms in 11 years of TRMM Precipitation Radar (PR) data has shown a tendency for squall lines to initiate and develop east of the Andes with a mesoscale organization similar to storms in the U.S. Great Plains (Rasmussen and Houze 2011). In subtropical South America, however, the topographical influence on the convective initiation and maintenance of the mesoscale convective systems (MCSs) is unique. The Andes and other mountainous terrain of Argentina focus deep convective initiation in the foothills of western Argentina (Romatschke and Houze 2010; Rasmussen and Houze 2011). Subsequent to initiation, the convection often evolves into propagating MCSs similar to those seen over the U.S. Great Plains sometimes producing damaging tornadoes, hail and floods across a wide agricultural region (Rasmussen and Houze 2011; Rasmussen et al. 2014b). The TRMM satellite was designed to determine the spatial and temporal variation of tropical and subtropical rainfall amounts and storm structures around the globe with the goal of understanding the factors controlling the precipitation. However, the TRMM PR algorithm significantly underestimates surface rainfall in deep convection over land (Nesbitt et al. 2004; Iguchi et al. 2009; Kozu et al. 2009). When the algorithm rates are compared to a range of conventional Z-R relations, the rain bias tends to be

  2. Influence of spatial resolution on precipitation simulations for the central Andes Mountains

    NASA Astrophysics Data System (ADS)

    Trachte, Katja; Bendix, Jörg

    2013-04-01

    The climate of South America is highly influenced by the north-south oriented Andes Mountains. Their complex structure causes modifications of large-scale atmospheric circulations resulting in various mesoscale phenomena as well as a high variability in the local conditions. Due to their height and length the terrain generates distinctly climate conditions between the western and the eastern slopes. While in the tropical regions along the western flanks the conditions are cold and arid, the eastern slopes are dominated by warm-moist and rainy air coming from the Amazon basin. Below 35° S the situation reverses with rather semiarid conditions in the eastern part and temperate rainy climate along southern Chile. Generally, global circulation models (GCMs) describe the state of the global climate and its changes, but are disabled to capture regional or even local features due to their coarse resolution. This is particularly true in heterogeneous regions such as the Andes Mountains, where local driving features, e. g. local circulation systems, highly varies on small scales and thus, lead to a high variability of rainfall distributions. An appropriate technique to overcome this problem and to gain regional and local scale rainfall information is the dynamical downscaling of the global data using a regional climate model (RCM). The poster presents results of the evaluation of the performance of the Weather Research and Forecasting (WRF) model over South America with special focus on the central Andes Mountains of Ecuador. A sensitivity study regarding the cumulus parametrization, microphysics, boundary layer processes and the radiation budget is conducted. With 17 simulations consisting of 16 parametrization scheme combinations and 1 default run a suitable model set-up for climate research in this region is supposed to be evaluated. The simulations were conducted in a two-way nested mode i) to examine the best physics scheme combination for the target and ii) to

  3. Flexural and gravity modelling of the Mérida Andes and Barinas Apure Basin, Western Venezuela

    NASA Astrophysics Data System (ADS)

    Chacín, Luis; Jácome, María I.; Izarra, Carlos

    2005-08-01

    The kinematic evolution of the Barinas-Apure Basin and the southern Mérida Andes from Lower Miocene to the Present is numerically modelled using flexural isostatic theory and geophysical and geological data. Two published regional transects are used to build up a reference section, which is then used to constrain important parameters (e.g. shortenings and sedimentary thicknesses) for the flexural modelling. To control the location of the main fault system in the flexural model earthquake information is also used. The estimated flexural elastic thickness of the South American lithosphere beneath the Barinas-Apure Basin and the Mérida Andes Range is 25 km. The value for the final total shortening is 60 km. The flexural isostatic model shows that the Andean uplift has caused the South American lithosphere subsidence and the development of the Barinas-Apure Basin. In addition, gravity modelling was used to understand deep crustal features that could not be predicted by flexural theory. Consequently, the best-fit flexural model is used to build a gravity model across the Mérida Andes and the Barinas-Apure Basin preserving the best-controlled structural features from the flexural modelling (e.g. basin wavelength and depth) and slightly changing the main bodies density values and deep crustal structures. The final gravity model is intended to be representative of the major features affecting the gravity field in the study area. The predicted morphology in the lower crustal level of the final gravity model favours the hypothesis of a present delamination or megathrust of the Maracaibo crust over the South American Shield. This process would use the Conrad discontinuity as a main detachment surface within an incipient NW dipping continental subduction.

  4. Exploring the Influence of Topography on Seismicity Patterns in the Northern Chile Andes

    NASA Astrophysics Data System (ADS)

    Shrivastava, M. N.; Gonzalez, G.; Moreno, M.

    2014-12-01

    The high topographic of the Andes has been resulted from the long-lasting and ongoing convergence between Nazca and South America plates. The build-up of the high topographic Andes does not only have reduced the convergent rate in the long-term but may have also influenced the short-term patterns of seismicity. The high mountains and the west flank of the Northern Chile is experiencing shallow and deep seismicity, with notable along-strike variations. Motivated by these considerations, we integrate modeling of Gravitational Potential Energy (GPE) and Global Positioning System (GPS) observations to investigate the control of the topography on the seismicity distribution. In this attempt, it is hypothesized that shallow seismicity is strongly influenced by the GPE in the range per unit area (1.45 -1.66) x1014 N/m due to high topography. By calculating the deviatoric stress associated with GPE and strain rate from GPS velocities, we obtain depth integrated value of stress for the full thickness of the lithosphere and the state of the stress in the upper crust and seismogenic plate contact. The GPE field in combination with GPS derived strain rates are used to sketch the present deformation pattern in the northern Chile Andes in regard of the crustal seismicity. The results indicate that high GPE gradient exhibits significant relationships with the shallow earthquake activity in the region. Therefore region of large topographic, where earthquakes have not occurred in past years, may be considered as potentially seismic hazards. Therefore high GPE gradient factors should be considered in the studies of earthquake activity and seismic hazard estimation.

  5. Island radiation on a continental scale: exceptional rates of plant diversification after uplift of the Andes.

    PubMed

    Hughes, Colin; Eastwood, Ruth

    2006-07-01

    Species radiations provide unique insights into evolutionary processes underlying species diversification and patterns of biodiversity. To compare plant diversification over a similar time period to the recent cichlid fish radiations, which are an order of magnitude faster than documented bird, arthropod, and plant radiations, we focus on the high-altitude flora of the Andes, which is the most species-rich of any tropical mountains. Because of the recent uplift of the northern Andes, the upland environments where much of this rich endemic flora is found have been available for colonization only since the late Pliocene or Pleistocene, 2-4 million years (Myr) ago. Using DNA sequence data we identify a monophyletic group within the genus Lupinus representing 81 species endemic to the Andes. The age of this clade is estimated to be 1.18-1.76 Myr, implying a diversification rate of 2.49-3.72 species per Myr. This exceeds previous estimates for plants, providing the most spectacular example of explosive plant species diversification documented to date. Furthermore, it suggests that the high cichlid diversification rates are not unique. Lack of key innovations associated with the Andean Lupinus clade suggests that diversification was driven by ecological opportunities afforded by the emergence of island-like habitats after Andean uplift. Data from other genera indicate that lupines are one of a set of similarly rapid Andean plant radiations, continental in scale and island-like in stimulus, suggesting that the high-elevation Andean flora provides a system that rivals other groups, including cichlids, for understanding rapid species diversification.

  6. On Restoring Sedimentary Basins for Post-Depositional Deformation - Paleozoic Basins of the Central Andes

    NASA Astrophysics Data System (ADS)

    Bahlburg, H.

    2015-12-01

    The reconstruction and interpretation of sedimentary basins incorporated into folded and thrusted mountain belts is strongly limited by the style and intensity of shortening. This problem is exacerbated if deformation is polyphasic as is the case for the Paleozoic basins in the central Andes. Some of these have been deformed by folding and thrusting during at least 3 events in the Late Ordovician, the Late Paleozoic and Cenozoic. A realistic reconstruction of the original basin dimensions and geometries from outcrops and maps appears to be almost impossible. We present results of a stepwise reconstruction of the Paleozoic basins of the central Andes by restoring basin areas and fills accounting for crustal shortening. The structurally most prominent feature of the central Andes is the Bolivian Orocline which accomodated shortening in the last 45 Ma on the order of between 300 and 500 km. In a first step basins were restored by accounting for Cenozoic rotation and shortening by deconvolving the basins using an enhanced version of the oroclinal bending model of Ariagada et al. (2008). Results were then restored stepwise for older deformation. Constraints on these subsequent steps are significantly poorer as values of shortening can be derived only from folds and thusts apparent in outcrops. The amount of shortening accomodated on unexposed and therefore unknown thrusts can not be quantified and is a significant source of error very likely leading to an underestimation of the amount of shortening. Accepting these limitations, basin restoration results in an increase in basin area by ≥100%. The volumes of stratigraphically controlled basin fills can now be redistributed over the wider, restored area, translating into smaller rates of accumulation and hence required subsidence. The restored rates conform to those of equivalent modern basin settings and permit a more realistic and actualistic analysis of subsidence drivers and the respective tectonic framework.

  7. Simulations of the future precipitation climate of the Central Andes using a coupled regional climate model

    NASA Astrophysics Data System (ADS)

    Nicholls, S.; Mohr, K. I.

    2014-12-01

    The meridional extent and complex orography of the South American continent contributes to a wide diversity of climate regimes ranging from hyper-arid deserts to tropical rainforests to sub-polar highland regions. Global climate models, although capable of resolving synoptic-scale South American climate features, are inadequate for fully-resolving the strong gradients between climate regimes and the complex orography which define the Tropical Andes given their low spatial and temporal resolution. Recent computational advances now make practical regional climate modeling with prognostic mesoscale atmosphere-ocean coupled models, such as the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system, to climate research. Previous work has shown COAWST to reasonably simulate the both the entire 2003-2004 wet season (Dec-Feb) as validated against both satellite and model analysis data. More recently, COAWST simulations have also been shown to sensibly reproduce the entire annual cycle of rainfall (Oct 2003 - Oct 2004) with historical climate model input. Using future global climate model input for COAWST, the present work involves year-long cycle spanning October to October for the years 2031, 2059, and 2087 assuming the most likely regional climate pathway (RCP): RCP 6.0. COAWST output is used to investigate how global climate change impacts the spatial distribution, precipitation rates, and diurnal cycle of precipitation patterns in the Central Andes vary in these yearly "snapshots". Initial results show little change to precipitation coverage or its diurnal cycle, however precipitation amounts did tend drier over the Brazilian Plateau and wetter over the Western Amazon and Central Andes. These results suggest potential adjustments to large-scale climate features (such as the Bolivian High).

  8. The Glacier Inventory of the Central Andes of Argentina (31°-35°S)

    NASA Astrophysics Data System (ADS)

    Ferri Hidalgo, L.; Zalazar, L.; Castro, M.; Pitte, P.; Masiokas, M. H.; Ruiz, L.; Villalba, R.; Delgado, S.; Gimenez, M.; Gargantini, H.

    2015-12-01

    The National Law for protection of glaciers in Argentina envisages the development of a National Inventory of Glaciers. All glaciers and periglacial landforms which are important as strategic water resource must be properly identified and mapped. Here we present a detailed and complete glacier and rock glacier inventory of the Central Andes of Argentina between 31° and 35°S. This semi-arid region contains some of the highest mountains of South America and concentrates the second most glacierized area in Argentina after the Patagonian Andes. To develop the inventory, we used remotely sensed data and related techniques complemented with field surveys. Clean ice and perennial snowfields were identified applying an automatic extraction method on medium spatial-resolution images. Debris-covered and rock glaciers were manually digitized on higher spatial-resolution images. With minor modifications, the present digital inventory is consistent with GLIMS standards. For each glacier, we derived 38 database fields, adding five specific attributes for rock glaciers, which are not included in the original GLIMS database. In total we identified 8069 glaciers covering an area of 1768 km2. Debris-covered ice and rock glaciers represent 57% of the total inventoried area. In this region, rock glaciers are a common feature in the arid landscape and constitute an important water reserve at regional scale. Many glaciers were characterized by gradual transition from debris-covered glaciers, in the upper part, to rock glaciers, in the lower sector. The remaining 43% includes clean ice glaciers and permanent snowfields. These are mostly mountain and valley-type glaciers with medium-to-small sizes. This detailed inventory constitutes a valuable contribution to the ongoing global efforts (e.g. WGI, RGI and GLIMS) to map the world's glaciers. It is also the base for ongoing glaciological, climatological and hydrological studies in this portion of southern Andes.

  9. Generation of the relationship between glacier area and volume for a tropical glacier in Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Liu, T.; Kinouchi, T.; Hasegawa, A.; Tsuda, M.; Iwami, Y.; Asaoka, Y.; Mendoza, J.

    2015-12-01

    In Andes, retreat of tropical glaciers is rapid, thus water resources currently available from glacierized catchments would be changed in its volume and temporal variations due to climate change and glacier shrinkage. The relationship between glacier area and volume is difficult to define however which is important to monitor glaciers especially those are remote or inaccessible. Water resources in La Paz and El Alto in Bolivia, strongly depend on the runoff from glacierized headwater catchments in the Cordillera Real, Andes, which is therefore selected as our study region.To predict annual glacier mass balances, PWRI-Distributed Hydrological Model (PWRI-DHM) was applied to simulate runoff from the partially glacierized catchments in high mountains (i.e. Condoriri-Huayna West headwater catchment located in the Cordillera Real, Bolivian Andes). PWRI-DHM is based on tank model concept in a distributed and 4-tank configuration including surface, unsaturated, aquifer, and river course tanks. The model was calibrated and validated with observed meteorological and hydrological data from 2011 to 2014 by considering different phases of precipitation, various runoff components from glacierized and non-glacierized areas, and the retarding effect by glacial lakes and wetlands. The model is then applied with MRI-AGCM outputs from 1987 to 2003 considering the shrinkage of glacier outlines since 1980s derived from Landsat data. Annual glacier mass balance in each 100m-grid was reproduced, with which the glacier area-volume relationship was generated with reasonable initial volume setting. Out study established a method to define the relationship between glacier area and volume by remote sensing information and glacier mass balances simulated by distributed hydrological model. Our results demonstrated that the changing trend of local glacier had a consistency the previous observed glacier area-volume relationship in the Cordillera Real.

  10. Setting practical conservation priorities for birds in the Western Andes of Colombia.

    PubMed

    Ocampo-Peñuela, Natalia; Pimm, Stuart L

    2014-10-01

    We aspired to set conservation priorities in ways that lead to direct conservation actions. Very large-scale strategic mapping leads to familiar conservation priorities exemplified by biodiversity hotspots. In contrast, tactical conservation actions unfold on much smaller geographical extents and they need to reflect the habitat loss and fragmentation that have sharply restricted where species now live. Our aspirations for direct, practical actions were demanding. First, we identified the global, strategic conservation priorities and then downscaled to practical local actions within the selected priorities. In doing this, we recognized the limitations of incomplete information. We started such a process in Colombia and used the results presented here to implement reforestation of degraded land to prevent the isolation of a large area of cloud forest. We used existing range maps of 171 bird species to identify priority conservation areas that would conserve the greatest number of species at risk in Colombia. By at risk species, we mean those that are endemic and have small ranges. The Western Andes had the highest concentrations of such species-100 in total-but the lowest densities of national parks. We then adjusted the priorities for this region by refining these species ranges by selecting only areas of suitable elevation and remaining habitat. The estimated ranges of these species shrank by 18-100% after accounting for habitat and suitable elevation. Setting conservation priorities on the basis of currently available range maps excluded priority areas in the Western Andes and, by extension, likely elsewhere and for other taxa. By incorporating detailed maps of remaining natural habitats, we made practical recommendations for conservation actions. One recommendation was to restore forest connections to a patch of cloud forest about to become isolated from the main Andes.

  11. Land Use Change and Hydrologic Processes in High-Elevation Tropical Watersheds of the Northern Andes

    NASA Astrophysics Data System (ADS)

    Avery, W. A.; Riveros-Iregui, D. A.; Covino, T. P.; Peña, C.

    2013-12-01

    The humid tropics cover one-fifth of the Earth's land surface and generate the greatest amount of runoff of any biome globally, but remain poorly understood and understudied. Humid tropical regions of the northern and central Andes have experienced greater anthropogenic land-use/land-cover (LULC) change than nearly any other high mountain system in the world. Vast expanses of this region are currently undergoing rapid transformation to farmland for production of potatoes and pasture for cattle grazing. Although the humid tropics have some of the highest runoff ratios, precipitation, and largest river flows in the world, there is a lack of scientific literature that addresses hydrologic processes in these regions and very few field observations are available to inform management strategies to ensure the sustainability of water resources of present and future generations. We seek to improve understanding of hydrologic processes and feedbacks in the humid tropics using existing and new information from two high-elevation watersheds that span a LULC gradient in the Andes Mountains of Colombia. One site is located in the preserved Chingaza Natural National Park in Central Colombia (undisturbed). The second site is located ~60 km to the northwest and has experienced considerable LULC change over the last 40 years. Combined, these watersheds deliver over 80% of the water resources to Bogotá and neighboring communities. These watersheds have similar climatological characteristics (including annual precipitation), but have strong differences in LULC which result in substantial differences in hydrologic response and streamflow dynamics. We present an overview of many of the pressing issues and effects that land degradation and climate change are posing to the long-term sustainability of water resources in the northern Andes. Our overarching goal is to provide process-based knowledge that will be useful to prevent, mitigate, or respond to future water crises along the Andean

  12. Climate Change Driven Implications on Spatial Distribution of High Andean Peatlands in the Central Andes

    NASA Astrophysics Data System (ADS)

    Otto, Marco; Gibbons, Richard E.

    2013-04-01

    High Andean peatlands are among the most unique habitats in the tropical Andes and certainly among the least studied. High Andean peatlands occur patchily in montane grassland and scrub below snow line and above tree line. These high-elevation peatlands are sustained by glacial runoff and seasonal precipitation. We used remote sensing data to estimate that peatland habitat is approximately 2.5 % of our study region in the Puna, an ecoregion located in the high Andes above 4000 m a.s.l. Individual sizes of our estimated peatland polygons ranged from 0.72 ha to 1079 ha with a mean size of 4.9 ha. Climate change driven implications on spatial distribution of high Andean peatlands were assessed in two ways. First, we estimated the effect of predicted regional temperature increase by using the standard lapse rate of 2° C per 300 m for assessing peatland habitat patches that would remain above a critical thermocline. Nearly 80% of peatland habitat patches were predicted to occur below the thermocline if the prediction of 4° C temperature increase is realized. The second assessment relied on the quantified assumption that permanent snow or glacier cover, topographic characteristics (e.g. slope) and precipitation of a basin are essential variables in the occurrence of high Andean peatlands. All 17 basins were predicted to have a decrease in peatland habitat due to snow line uplift, decrease in precipitation and consequent insufficient wetland inflows. Total habitat loss was predicted for two basins in the semi-arid part of the study area with a snow line uplift to 5600 m and a projected decrease in precipitation of 1 mm per year over the next 40 years. A combined result of both assessments provides important information on climate change driven implications on the hydrology of high Andean peatlands and potential consequences for their spatial distribution within the Central Andes.

  13. Constraints on deformation of the Southern Andes since the Cretaceous from anisotropy of magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Maffione, Marco; Hernandez-Moreno, Catalina; Ghiglione, Matias C.; Speranza, Fabio; van Hinsbergen, Douwe J. J.; Lodolo, Emanuele

    2015-12-01

    The southernmost segment of the Andean Cordillera underwent a complex deformation history characterized by alternation of contractional, extensional, and strike-slip tectonics. Key elements of southern Andean deformation that remain poorly constrained, include the origin of the orogenic bend known as the Patagonian Orocline (here renamed as Patagonian Arc), and the exhumation mechanism of an upper amphibolite facies metamorphic complex currently exposed in Cordillera Darwin. Here, we present results of anisotropy of magnetic susceptibility (AMS) from 22 sites in Upper Cretaceous to upper Eocene sedimentary rocks within the internal structural domain of the Magallanes fold-and-thrust belt in Tierra del Fuego (Argentina). AMS parameters from most sites reveal a weak tectonic overprint of the original magnetic fabric, which was likely acquired upon layer-parallel shortening soon after sedimentation. Magnetic lineation from 17 sites is interpreted to have formed during compressive tectonic phases associated to a continuous ~ N-S contraction. Our data, combined with the existing AMS database from adjacent areas, show that the Early Cretaceous-late Oligocene tectonic phases in the Southern Andes yielded continuous contraction, variable from ~ E-W in the Patagonian Andes to ~ N-S in the Fuegian Andes, which defined a radial strain field. A direct implication is that the exhumation of the Cordillera Darwin metamorphic complex occurred under compressive, rather than extensional or strike-slip tectonics, as alternatively proposed. If we agree with recent works considering the curved Magallanes fold-and-thrust belt as a primary arc (i.e., no relative vertical-axis rotation of the limbs occurs during its formation), then other mechanisms different from oroclinal bending should be invoked to explain the documented radial strain field. We tentatively propose a kinematic model in which reactivation of variably oriented Jurassic faults at the South American continental margin

  14. Development of a minigenome system for Andes virus, a New World hantavirus

    PubMed Central

    Brown, Kyle S.; Ebihara, Hideki; Feldmann, Heinz

    2012-01-01

    The development of reverse genetics systems for negative-stranded RNA viruses is a rapidly evolving field that has greatly advanced the study of the many different aspects of the viral life cycle. Andes virus (ANDV) is a highly pathogenic hantavirus found in South America that causes hantavirus pulmonary syndrome but to date remains poorly characterized due to the lack of a reverse genetics system for genetic manipulation. Here, we describe the first successful minigenome system for a New World hantavirus, as well as many of the obstacles that still exist in the development of such a system. PMID:22821183

  15. On the influence of the Andes on the general circulation of the Southern Hemisphere

    SciTech Connect

    Walsh, K. )

    1994-06-01

    An experiment is described in which the Andean tomography in a general circulation model is replaced by an envelope topography and a new model climatology is produced. The resulting simulation is compared to the model climatology of an experiment in which the topography of the Andean region is completely removed. Apart from dramatic local effects, the Andean mountain range appears to exert little influence on the general circulation of the Southern Hemisphere. The experiments are assessed in the context of the geologically recent uplift of the Andes. 26 refs., 7 figs.

  16. A case of atmospheric contamination at the slopes of the Los Andes mountain range

    NASA Astrophysics Data System (ADS)

    Romo-Kröger, Carlos M.; Llona, Felipe

    High heavy element contents were found in the aerosol in part of the Chilean central Los Andes mountain range. An important contamination source was found to be the copper mine, El Teniente. Samples were taken with battery-powered Stacked Filter Units (SFU), and sites were reached by using mules. The analysis was done by the PIXE system at the University of Chile. A very definite relation between the distance to El Teniente and the aerosol content of heavy metals (Cu, Zn and As) and sulfur was found. Some discussion about the peculiarity of this sampling and the implications of the results is carried out.

  17. A new yellow species of glassfrog (Centrolenidae: Nymphargus) from the Amazonian slopes of the Ecuadorian Andes.

    PubMed

    Guayasamin, Juan M

    2013-01-01

    I describe a new glassfrog from the cloud forest of the Andes of southwestern Ecuador (Plan de Milagro-Gualaceo road; 3.0077°S, 78.53318°W), at elevations between 2140-2160 m. The new species is distinguished mostly by having a pale yellow dorsal coloration instead of the green that characterizes most centrolenids. Morphological traits (i.e., reduced webbing between Fingers III and IV and lack of humeral spines) support the placement of the new species in the genus Nymphargus.

  18. Tectonic geomorphology of the Andes with SIR-A and SIR-B

    NASA Technical Reports Server (NTRS)

    Bloom, Arthur L.; Fielding, Eric J.

    1986-01-01

    Data takes from SIR-A and SIR-B (Shuttle Imaging Radar) crossed all of the principal geomorphic provinces of the central Andes between 17 and 34 S latitude. In conjunction with Thematic Mapping images and photographs from hand-held cameras as well as from the Large Format Camera that was flown with SIR-B, the radar images give an excellent sampling of Andean geomorphology. In particular, the radar images show new details of volcanic rocks and landforms of late Cenozoic age in the Puna, and the exhumed surfaces of tilted blocks of Precambrian crystalline basement in the Sierras Pampeanas.

  19. Spatial distribution of rock glaciers in the semi-arid Andes of Argentina

    NASA Astrophysics Data System (ADS)

    Blöthe, Jan Henrik; Halla, Christian; Schrott, Lothar; Götz, Joachim; Trombotto, Dario

    2016-04-01

    Active rock glaciers are indicators for permafrost in periglacial environments of high mountain areas. Within the permafrost body and the seasonally frozen active layer, these rock glaciers potentially store large amounts of water. Especially in semiarid mountain belts, such as the central Andes of Argentina, rock glaciers attain several kilometres in length, covering surface areas of >106 m2. Here, rock glaciers even outrange ice glaciers in cumulative area and absolute number, indicating they might constitute a large water reservoir in this semiarid part of the Andes. Despite their potential hydrological importance, our knowledge about the rock glaciers' spatial distribution, subsurface composition and absolute ice content is still very limited. Our study addresses this shortcoming and aims at assessing the hydrological significance of rock glacier permafrost in the semi-arid Andes of Argentina by combining local geophysical investigations with regional remote sensing analysis. Our research focuses on the central Andes between 30°S and 33°S, where we have compiled an inventory that comprises more than 1200 rock glaciers, as well as 154 clear-ice and debris-covered glaciers. Two field sites that bracket this regional study area towards their northern and southern edge have been selected for local geophysical investigations. At these locations, earlier studies detected the presence of rock glacier permafrost by thermal monitoring and geophysical prospection. Preliminary results of the regional spatial distribution indicate that the spatial density of rock glaciers increases towards the south, concomitant with a twofold increase in mean annual precipitation. Rock glacier density peaks in the area of the Aconcagua massif, while precipitation is further increasing towards the south. Simultaneously, the lower altitudinal limit of intact rock glaciers slightly decreases, with the lowest rock glacier toe positions in the northern study area located at ~3800 m a. s. l

  20. A new yellow species of glassfrog (Centrolenidae: Nymphargus) from the Amazonian slopes of the Ecuadorian Andes.

    PubMed

    Guayasamin, Juan M

    2013-01-01

    I describe a new glassfrog from the cloud forest of the Andes of southwestern Ecuador (Plan de Milagro-Gualaceo road; 3.0077°S, 78.53318°W), at elevations between 2140-2160 m. The new species is distinguished mostly by having a pale yellow dorsal coloration instead of the green that characterizes most centrolenids. Morphological traits (i.e., reduced webbing between Fingers III and IV and lack of humeral spines) support the placement of the new species in the genus Nymphargus. PMID:26269825

  1. Effect of Vandetanib on Andes virus survival in the hamster model of Hantavirus pulmonary syndrome.

    PubMed

    Bird, Brian H; Shrivastava-Ranjan, Punya; Dodd, Kimberly A; Erickson, Bobbie R; Spiropoulou, Christina F

    2016-08-01

    Hantavirus pulmonary syndrome (HPS) is a severe disease caused by hantavirus infection of pulmonary microvascular endothelial cells leading to microvascular leakage, pulmonary edema, pleural effusion and high case fatality. Previously, we demonstrated that Andes virus (ANDV) infection caused up-regulation of vascular endothelial growth factor (VEGF) and concomitant downregulation of the cellular adhesion molecule VE-cadherin leading to increased permeability. Analyses of human HPS-patient sera have further demonstrated increased circulating levels of VEGF. Here we investigate the impact of a small molecule antagonist of the VEGF receptor 2 (VEGFR-2) activation in vitro, and overall impact on survival in the Syrian hamster model of HPS. PMID:27233645

  2. Phage Display Selection of Cyclic Peptides That Inhibit Andes Virus Infection▿

    PubMed Central

    Hall, Pamela R.; Hjelle, Brian; Njus, Hadya; Ye, Chunyan; Bondu-Hawkins, Virginie; Brown, David C.; Kilpatrick, Kathleen A.; Larson, Richard S.

    2009-01-01

    Specific therapy is not available for hantavirus cardiopulmonary syndrome caused by Andes virus (ANDV). Peptides capable of blocking ANDV infection in vitro were identified using antibodies against ANDV surface glycoproteins Gn and Gc to competitively elute a cyclic nonapeptide-bearing phage display library from purified ANDV particles. Phage was examined for ANDV infection inhibition in vitro, and nonapeptides were synthesized based on the most-potent phage sequences. Three peptides showed levels of viral inhibition which were significantly increased by combination treatment with anti-Gn- and anti-Gc-targeting peptides. These peptides will be valuable tools for further development of both peptide and nonpeptide therapeutic agents. PMID:19515773

  3. Lithosphere Removal in the Central Andes: Reconciling Seismic Images and Elevation History

    NASA Astrophysics Data System (ADS)

    Henderson, O.; Currie, C. A.

    2015-12-01

    Shortening of the upper crust should be accompanied by thickening of the deeper lithosphere. However, for many orogens, including the central Andes, geophysical and geological observations indicate that mantle lithosphere is spatially heterogeneous, being anomalously thin or absent. Seismic studies of the central Andes suggest that mantle lithosphere is locally removed. Also, present day elevations of the central Andean Plateau have been explained by rapid removal of mantle lithosphere over the last 10 Ma. Yet, the geological record is innately incomplete, and seismic tomography and receiver functions can offer only a present day snapshot of the subsurface. None of these techniques provides concrete insight into the physical processes responsible for current Andean elevations (3-5 km). A 2D plane-strain thermo-mechanical code, SOPALE, is used to examine the deep lithospheric dynamics connected to mantle lithosphere removal within a subduction zone setting, such as the Andes. Three models have been tested: removal by viscous dripping, by delamination, and a model with no removal. The removal models contain a high density eclogite root, creating a contrast between mantle lithosphere and mantle material. For the viscous drip models, mantle lithosphere is removed within 2.5-5 Myrs, descending subvertically through the mantle, causing subsequent surface rebound. Prior to this rebound, surface topography subsides locally over the dense root. This subsidence is influenced by crustal rheology, where weaker crustal rheologies produce deep, narrower basins (25-75 km wide, ~1 km deep), and stronger crustal rheologies produce shallow, broader basins (300-400 km wide, ~0.5 km deep). Delamination, which involves the coherent removal of mantle lithosphere along the Moho, affects a larger region, and is reflected in broader basins that extend into the back-arc. In all models, the deep lithosphere dynamics have an appreciable effect on surface topography, therefore, removal events

  4. Jürgen Stock: From One End of the Andes to the Other

    NASA Astrophysics Data System (ADS)

    Vivas, A. K.; Stock, M. J.

    2015-05-01

    Jürgen Stock (1923-2004) will always be remembered for his work on astronomical site testing. He led the efforts to find the best place for CTIO, and his work had a large influence in the setting of other observatories in Chile. He was the first director of CTIO (1963-1966). After his time in Chile, he moved to the other end of the Andes and was in charge of the site selection and the construction of the only professional observatory in Venezuela, the Llano del Hato National Observatory.

  5. Prediction of extreme floods in the Central Andes by means of Complex Networks

    NASA Astrophysics Data System (ADS)

    Boers, Niklas; Bookhagen, Bodo; Barbosa, Henrique; Marwan, Norbert; Kurths, Jürgen; Marengo, Jose

    2014-05-01

    Based on a non-linear synchronisation measure and complex network theory, we present a novel framework for the prediction of extreme events of spatially embedded, interrelated time series. This method is general in the sense that it can be applied to any type of spatially sampled time series with significant interrelations, ranging from climate observables to biological or stock market data. In this presentation, we apply our method to extreme rainfall in South America and show how this leads to the prediction of more than 60% (90% during El Niño conditions) of extreme rainfall events in the eastern Central Andes of Bolivia and northern Argentina, with only 1% false alarms. From paleoclimatic to decadal time scales, the Central Andes continue to be subject to pronounced changes in climatic conditions. In particular, our and past work shows that frequency as well as magnitudes of extreme rainfall events have increased significantly during past decades, calling for a better understanding of the involved climatic mechanisms. Due to their large spatial extend and occurrence at high elevations, these extreme events often lead to severe floods and landslides with disastrous socioeconomic impacts. They regularly affect tens of thousands of people and produce estimated costs of the order of several hundred million USD. Alongside with the societal value of predicting natural hazards, our study provides insights into the responsible climatic features and suggests interactions between Rossby waves in polar regions and large scale (sub-)tropical moisture transport as a driver of subseasonal variability of the South American monsoon system. Predictable extreme events result from the propagation of extreme rainfall from the region of Buenos Aires towards the Central Andes given characteristic atmospheric conditions. Our results indicate that the role of frontal systems originating from Rossby waves in polar latitudes is much more dominant for controlling extreme rainfall in

  6. STS-31 Hubble Space Telescope (HST) is released by RMS over Andes Mountains

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Hubble Space Telescope (HST), with solar array (SA) wings and high gain antennae (HGA) masts fully extended, is released by the remote manipulator system (RMS) end effector. The STS-31 crew aboard Discovery, Orbiter Vehicle (OV) 103, set the HST into Earth orbit high above the Andes Mountains. Parts of Bolivia, Peru, Chile, and Argentina are visible. This picture covers a huge area of the western half of South America stretching from 14 degrees south latitude to 23 degrees, about 1,000 kilometers.

  7. Temporal distribution of human rotavirus serotypes 1,2,3, and 4 in Venezuelan children with gastroenteritis during 1979-1989.

    PubMed

    White, L; García, D; Boher, Y; Blanco, M; Pérez, M; Romer, H; Flores, J; Pérez-Schael, I

    1991-06-01

    The temporal distribution and clinical severity of rotavirus VP7 serotypes 1, 2, 3, and 4 recovered from 427 Venezuelan children with acute gastroenteritis over a period of 11 years were studied. Rotavirus VP7 serotype was established by ELISA serotyping in 298 (69.78%) of the specimens while the serotype of the remaining 129 (30.21%) samples could not be determined. Of the specimens typed, 85 (19.90% of the total) were serotype 1, 43 (10.07%) were serotype 2, 105 (24.59%) were serotype 3, and 65 (15.22%) were serotype 4. Yearly changes in the frequency of individual serotypes were observed. The predominance of a single serotype with minor contribution from others was noted every year. In this study, serotype 1 appears to induce a less severe illness in comparison with serotypes 2, 3, and 4. No apparent association between the proportion of each serotype and the children's age were found.

  8. Purification, crystallization and X-ray diffraction analysis of the C-terminal protease domain of Venezuelan equine encephalitis virus nsP2

    PubMed Central

    Russo, Andrew T.; Watowich, Stanley J.

    2006-01-01

    The C-terminal region of Venezuelan equine encephalitis virus (VEEV) nsP2 is responsible for proteolytic processing of the VEEV polyprotein replication complex. This action regulates the activity of the replication complex and is essential for viral replication, thus making nsP2 a very attractive target for development of VEEV therapeutics. The 338-amino-acid C-terminal region of VEEV nsP2 has been overexpressed in Escherichia coli, purified and crystallized. Crystals diffract to beyond 2.5 Å resolution and belong to the orthorhombic space group P212121. Isomorphous heavy-atom derivatives suitable for phase analysis have been obtained and work on building a complete structural model is under way. PMID:16754969

  9. TCF7L2 rs7903146 polymorphism is associated with gastric cancer: A case-control study in the Venezuelan population

    PubMed Central

    Torres, Keila; Labrador, Luis; Valderrama, Elvis; Chiurillo, Miguel Angel

    2016-01-01

    AIM: To explore the association between TCF7L2 rs12255372 and rs7903146 single nucleotide polymorphisms (SNPs) and gastric cancer risk in Venezuelan patients. METHODS: We performed a case-control study including 122 paraffin-embedded archived intestinal-type gastric cancer samples and 129 biopsies obtained by superior endoscopy from chronic gastritis patients. Gastric cancer samples were classified according the degree of carcinoma differentiation. Genomic DNA was extracted from tissues, and the two SNPs of TCF7L2 gene (rs12255372 and rs7903146) were genotyped by polymerase chain reaction-restriction fragment length polymorphism reactions. Multiple regression analysis with adjustments for age and gender were performed and best-fitting models of inheritance were determined. Statistic powers were post-hoc calculated. RESULTS: After adjusting for age and sex the TCF7L2 rs7903146 TT genotype was associated with gastric cancer risk under the recessive genetic model (OR = 3.11, 95%CI: 1.22-7.92, P = 0.017). We further investigated the distribution of rs12255372 and rs7903146 genotypes according gastric cancer stratified by degree of differentiation, and we observed that carriers of rs7903146 T allele (CT + TT vs CC) had a significantly increased risk of moderate/well differentiated gastric cancer (dominant model, OR = 2.55, 95%CI: 1.35-4.80, P = 0.004), whereas the rs7903146 TT genotype was associated with poorly differentiated gastric cancer in the recessive model (OR = 3.65, 95%CI: 1.25-10.62, P = 0.018). We did not find association between rs12255372 SNP and the susceptibility of developing gastric cancer. CONCLUSION: TCF7L2 rs7903146 polymorphism is associated with gastric cancer risk in the Venezuelan population, and could be related to determine the degree of differentiation of tumor cells. PMID:27605886

  10. TCF7L2 rs7903146 polymorphism is associated with gastric cancer: A case-control study in the Venezuelan population

    PubMed Central

    Torres, Keila; Labrador, Luis; Valderrama, Elvis; Chiurillo, Miguel Angel

    2016-01-01

    AIM: To explore the association between TCF7L2 rs12255372 and rs7903146 single nucleotide polymorphisms (SNPs) and gastric cancer risk in Venezuelan patients. METHODS: We performed a case-control study including 122 paraffin-embedded archived intestinal-type gastric cancer samples and 129 biopsies obtained by superior endoscopy from chronic gastritis patients. Gastric cancer samples were classified according the degree of carcinoma differentiation. Genomic DNA was extracted from tissues, and the two SNPs of TCF7L2 gene (rs12255372 and rs7903146) were genotyped by polymerase chain reaction-restriction fragment length polymorphism reactions. Multiple regression analysis with adjustments for age and gender were performed and best-fitting models of inheritance were determined. Statistic powers were post-hoc calculated. RESULTS: After adjusting for age and sex the TCF7L2 rs7903146 TT genotype was associated with gastric cancer risk under the recessive genetic model (OR = 3.11, 95%CI: 1.22-7.92, P = 0.017). We further investigated the distribution of rs12255372 and rs7903146 genotypes according gastric cancer stratified by degree of differentiation, and we observed that carriers of rs7903146 T allele (CT + TT vs CC) had a significantly increased risk of moderate/well differentiated gastric cancer (dominant model, OR = 2.55, 95%CI: 1.35-4.80, P = 0.004), whereas the rs7903146 TT genotype was associated with poorly differentiated gastric cancer in the recessive model (OR = 3.65, 95%CI: 1.25-10.62, P = 0.018). We did not find association between rs12255372 SNP and the susceptibility of developing gastric cancer. CONCLUSION: TCF7L2 rs7903146 polymorphism is associated with gastric cancer risk in the Venezuelan population, and could be related to determine the degree of differentiation of tumor cells.

  11. Potential particulate impacts at the Grand Canyon from northwestern Mexico.

    PubMed

    Eatough, D J; Green, M; Moran, W; Farber, R

    2001-08-10

    Project MOHAVE was a major air quality and visibility research program conducted from 1990 to 1999 to investigate the causes of visibility impairment in the Grand Canyon National Park region. At Meadview, a remote monitoring site just west of the Grand Canyon National Park, on September 1 and 2, 1992, the concentrations of sulfate (3.1 and 4.3 microg sulfate/m3) were the highest seen in 6 years of monitoring at this site. During this period, the concentrations of SO2 at Meadview were also abnormally high and approximately three times the sulfate concentrations, on a nmol/m3 basis. High concentrations of sulfate and SO2 extended south into southern Arizona and northwestern Mexico. Based on ambient atmospheric conditions, emissions from the Mohave Power Project (MPP) 110 km upwind of Meadview could not have been responsible for the majority of the regionally observed sulfur oxides. The geographical distribution of SO2 and sulfate, and available source information suggest that northwestern Mexico was a significant source of the unusually high observed sulfur oxides. A CMB model developed during Project MOHAVE was used to apportion sulfur oxides at Meadview and other sampling sites throughout the study region for August 31-September 2, 1992. The results indicate that the contribution of MPP to sulfate at Meadview was typical. However, the transport of SOx from northwestern Mexico was elevated throughout much of the region during this time period. This led to the large increase in sulfate concentrations at Meadview on September 1 and 2. These results indicate that emissions from Mexico can be a significant source of particulate material in the Grand Canyon.

  12. Rapid fluvial aggradation in response to climate change in northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Wickert, Andrew; Schildgen, Taylor; Strecker, Manfred

    2015-04-01

    River channels near the edge of the northwestern Argentine Andes are rapidly aggrading at present, with preliminary estimates suggesting rates of ~20 cm yr-1. This mirrors cycles of extensive aggradation over the past 100,000 years that formed pronounced fill terraces along regional valley networks and record periods in which in which climate-driven sediment supply overcame uplift-driven river incision (Robinson et al, 2005). Here we use the new SedFlow model (Heimann et al., 2014) to help us understand the causes and spread of aggradation across these basins in the modern system, with the additional eventual goal to better interpret the geologic record. We provide field-derived grain-size distributions, field-measured and remotely-sensed channel widths and valley slopes, and a variety of possible sediment source locations and amounts as inputs to SedFlow, which routes sediment through the fluvial channel network to produce time-evolving predictions of aggradation and incision. We compare these predictions against changes in topography measured by IceSAT (Zwally et al., 2014) and field surveys. We initially test the system response to a series of isolated sediment inputs to observe interactions between tributary systems and the mainstem river. Recent observations indicate that debris-flow induced landslides are important contributors to aggradation in these rivers (Cencetti and Rivelli, 2011). These and other sediment production and transport processes are likely driven by variations in the El Niño Southern Oscillation (ENSO) (Bookhagen and Strecker, 2009). Therefore, we then run SedFlow with sediment inputs distributed across the landscape based on locations where ENSO influences may trigger enhanced landsliding. These model experiments help us towards our end goal of providing a more quantitative basis to interpret field observations of landscape response to changing patterns of precipitation. References: Bookhagen, B. and Strecker, M.: Amazonia: Landscape and

  13. 40. NORTH ACROSS WOODWORKING AREA IN NORTHWESTERN QUADRANT OF FACTORY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. NORTH ACROSS WOODWORKING AREA IN NORTHWESTERN QUADRANT OF FACTORY ACROSS STACKED LUMBER ON SAWHORSES TOWARD CIRCA 1900 THICKNESS PLANER, SHOP-MADE BELT GUARD, AND BELOW THE SKYLIGHT OVERHEAD LINE SHAFT, BELTS, AND PULLEYS. BEYOND THE LUMBER ON A WHEELED WORK STATION ARE CIRCA 1900 ROLLS FOR BENDING PROPER CURVATURE IN STEEL WINDMILL BLADES AND CIRCA 1900 BEADING MACHINE FOR FORMING CREASES IN THE EDGES OF SHEET METAL PARTS SUCH AS WHEEL BLADES. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  14. Middle cretaceous carbonate reservoirs, Fahud Field and northwestern Oman: discussion

    SciTech Connect

    Brennan, P.

    1985-05-01

    A discussion is presented of the Cretaceous formations involved in Fahud field. Along the Trucial Coast, as in northwestern Oman, it is not difficult to date the time of formation of the foredeep. This article provides a stratigraphic correlation chart for the Cretaceous along the Arabian side of the Arabian Gulf. The terminology presented on this correlation chart reflects oil-industry usage in the area, including correlations published by Owen and Nasr, Loutfi and Jaber, Arabian American Oil Company, Beydoun and Dunnington, and Hassan et al.

  15. Shelf sandstones of Twowells tongue, Dakota sandstone, northwestern New Mexico

    SciTech Connect

    Wolter, N.R.; Nummedal, D.

    1988-02-01

    The Dakota Sandstone of northwestern New Mexico is composed of basal continental strata and three marine sandstone tongues, which intertongue with the Mancos Shale. The late Cenomanian Twowells tongue was the last tongue deposited in the Dakota transgressive systems tract. This tongue is most commonly gradationally underlain by the Whitewater Arroyo shale tongue and abruptly overlain by the Rio Salado tongue of the Mancos Shale. Data collected from 85 outcrop sections and 180 electric well logs, from the San Juan, Acoma, and Zuni basins, indicates that the Twowells tongue represents three phases of marine deposition.

  16. African Oral Traditions: Riddles Among The Haya of Northwestern Tanzania

    NASA Astrophysics Data System (ADS)

    Ishengoma, Johnson M.

    2005-05-01

    This study argues for the integration of African oral traditions and other elements of traditional learning into the modern school curriculum. It thus contributes to supporting the increased relevance of education to local communities. In particular, using the example of riddles collected from one of the main ethnic groups in Northwestern Tanzania, the Haya people, the present study challenges the views of those social and cultural anthropologists who hold that African riddles have no substantially meaningful educational value. Instead, it is maintained that riddles make an important contribution to children's full participation in the social, cultural, political, and economic life of African communities, especially by fostering critical thinking and transmitting indigenous knowledge.

  17. Climatic Limits on Landscape Development in the Northwestern Himalaya

    PubMed

    Brozović; Burbank; Meigs

    1997-04-25

    The interaction between tectonism and erosion produces rugged landscapes in actively deforming regions. In the northwestern Himalaya, the form of the landscape was found to be largely independent of exhumation rates, but regional trends in mean and modal elevations, hypsometry (frequency distribution of altitude), and slope distributions were correlated with the extent of glaciation. These observations imply that in mountain belts that intersect the snowline, glacial and periglacial processes place an upper limit on altitude, relief, and the development of topography irrespective of the rate of tectonic processes operating.

  18. Climate Change and Neotectonic History of Northwestern China

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Chadwick, Oliver; Evans, Diane; Gillespie, Alan; Peltzer, Gilles; Tapponnier, Paul

    1996-01-01

    The progress, results and future plans for the following objectives are presented: (1) To compare the types, rates, and magnitudes of surficial modification processes that have operated in Northwest China and the Southwestern U.S.; (2) To quantify and understand the basis of the remote sensing signatures of these processes to allow extrapolation from field sites to regional maps and to allow comparisons between widely separated arid regions; (3) To use the resulting chronologies to help define the temporal and spatial distribution of continental climate changes; and (4) Determine the ages of movements on some of the active faults in Northwestern China.

  19. 78 FR 53175 - The Northwestern Mutual Life Insurance Company, et al.;

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-28

    ... COMMISSION The Northwestern Mutual Life Insurance Company, et al.; Notice of Application Agency: Securities... Section 17(b) of the Act from Section 17(a) of the Act. Applicants: The Northwestern Mutual Life Insurance...''), under each of the variable annuity contracts and variable life insurance policies issued by the...

  20. A new species of Telmatobius (Amphibia, Anura, Telmatobiidae) from the Pacific slopes of the Andes, Peru.

    PubMed

    Catenazzi, Alessandro; García, Víctor Vargas; Lehr, Edgar

    2015-01-01

    We describe a new species of Telmatobius from the Pacific slopes of the Andes in central Peru. Specimens were collected at 3900 m elevation near Huaytará, Huancavelica, in the upper drainage of the Pisco river. The new species has a snout-vent length of 52.5 ± 1.1 mm (49.3-55.7 mm, n = 6) in adult females, and 48.5 mm in the single adult male. The new species has bright yellow and orange coloration ventrally and is readily distinguished from all other central Peruvian Andean species of Telmatobius but Telmatobiusintermedius by having vomerine teeth but lacking premaxillary and maxillary teeth, and by its slender body shape and long legs. The new species differs from Telmatobiusintermedius by its larger size, flatter head, and the absence of cutaneous keratinized spicules (present even in immature females of Telmatobiusintermedius), and in males by the presence of minute, densely packed nuptial spines on dorsal and medial surfaces of thumbs (large, sparsely packed nuptial spines in Telmatobiusintermedius). The hyper-arid coastal valleys of Peru generally support low species richness, particularly for groups such as aquatic breeding amphibians. The discovery of a new species in this environment, and along a major highway crossing the Andes, shows that much remains to be done to document amphibian diversity in Peru.

  1. Late Pleistocene equilibrium-line reconstructions in the northern Peruvian Andes

    USGS Publications Warehouse

    Rodbell, D.T.

    1992-01-01

    ELA reconstructions using the toe-to-headwall-altitude ratio method for paleoglaciers in the Cordilleras Blanca and Oriental, northern Peruvian Andes indicate that ELAs during the last glacial maximum (LGM; marine isotope stage 2)) were c.4300 m in the Cordillera Blanca, c.3900-3600 m on the west side of the Cordillera Oriental, and c.3200 m on the east (Amazon Basin) side of the Cordillera Oriental. Comparison with estimated modern ELAs and glaciation thresholds indicate that ELA depression ranged from c.700 m in the Cordillera Blanca to c.1200 m on the east side of the Cordillera Oriental. Palynological evidence for drier conditions during the LGM in the tropical Andes suggests that ELA depression of this amount involved a temperature reduction (>5-6??C) that greatly exceeded the tropical sea-surface temperature depression estimates of CLIMAP (<2??C). The west to east increase in ELA depression during the LGM indicates that the steep modern precipitation gradients may have been even steeper during the LGM. -from Author

  2. The Loncopué Trough: A Cenozoic basin produced by extension in the southern Central Andes

    NASA Astrophysics Data System (ADS)

    Folguera, Andrés; Rojas Vera, Emilio; Bottesi, Germán; Zamora Valcarce, Gonzalo; Ramos, Victor A.

    2010-05-01

    The Loncopué Trough is located in the hinterland Andean zone between 36°30' and 39°S. It constitutes a topographic low bounded by normal faults and filled by lavas and sediments less than 5 Ma old. Reprocessed seismic lines show wedge-like depocenters up to 1700 m deep associated with high-angle faults, correlated with the 27-17 Ma Cura Mallín basin deposits, and buried beneath Pliocene to Quaternary successions and Late Miocene foreland sequences. The southern Central Andes seem to have been under extension in the hinterland zone some 27 Ma ago and again at approximately 5 Ma ago. This last extensional period could have been the product of slab steepening after a shallow subduction cycle in the area, although other alternatives are discussed. Orogenic wedge topography, altered by the first extensional stage in the area, was recovered through Late Miocene inversion, and was associated with foreland sequences. However, since the last extension (<5 Ma) the Andes have not recovered their characteristic contractional behavior that controlled past orogenic growth.

  3. Bird conservation would complement landslide prevention in the Central Andes of Colombia.

    PubMed

    Ocampo-Peñuela, Natalia; Pimm, Stuart L

    2015-01-01

    Conservation and restoration priorities often focus on separate ecosystem problems. Inspired by the November 11th (2011) landslide event near Manizales, and the current poor results of Colombia's Article 111 of Law 99 of 1993 as a conservation measure in this country, we set out to prioritize conservation and restoration areas where landslide prevention would complement bird conservation in the Central Andes. This area is one of the most biodiverse places on Earth, but also one of the most threatened. Using the case of the Rio Blanco Reserve, near Manizales, we identified areas for conservation where endemic and small-range bird diversity was high, and where landslide risk was also high. We further prioritized restoration areas by overlapping these conservation priorities with a forest cover map. Restoring forests in bare areas of high landslide risk and important bird diversity yields benefits for both biodiversity and people. We developed a simple landslide susceptibility model using slope, forest cover, aspect, and stream proximity. Using publicly available bird range maps, refined by elevation, we mapped concentrations of endemic and small-range bird species. We identified 1.54 km(2) of potential restoration areas in the Rio Blanco Reserve, and 886 km(2) in the Central Andes region. By prioritizing these areas, we facilitate the application of Article 111 which requires local and regional governments to invest in land purchases for the conservation of watersheds.

  4. Bird conservation would complement landslide prevention in the Central Andes of Colombia.

    PubMed

    Ocampo-Peñuela, Natalia; Pimm, Stuart L

    2015-01-01

    Conservation and restoration priorities often focus on separate ecosystem problems. Inspired by the November 11th (2011) landslide event near Manizales, and the current poor results of Colombia's Article 111 of Law 99 of 1993 as a conservation measure in this country, we set out to prioritize conservation and restoration areas where landslide prevention would complement bird conservation in the Central Andes. This area is one of the most biodiverse places on Earth, but also one of the most threatened. Using the case of the Rio Blanco Reserve, near Manizales, we identified areas for conservation where endemic and small-range bird diversity was high, and where landslide risk was also high. We further prioritized restoration areas by overlapping these conservation priorities with a forest cover map. Restoring forests in bare areas of high landslide risk and important bird diversity yields benefits for both biodiversity and people. We developed a simple landslide susceptibility model using slope, forest cover, aspect, and stream proximity. Using publicly available bird range maps, refined by elevation, we mapped concentrations of endemic and small-range bird species. We identified 1.54 km(2) of potential restoration areas in the Rio Blanco Reserve, and 886 km(2) in the Central Andes region. By prioritizing these areas, we facilitate the application of Article 111 which requires local and regional governments to invest in land purchases for the conservation of watersheds. PMID:25737819

  5. Quaternary Ice-Age dynamics in the Colombian Andes: developing an understanding of our legacy.

    PubMed Central

    Hooghiemstra, Henry; Van der Hammen, Thomas

    2004-01-01

    Pollen records from lacustrine sediments of deep basins in the Colombian Andes provide records of vegetation history, the development of the floristic composition of biomes, and climate variation with increasing temporal resolution. Local differences in the altitudinal distribution of present-day vegetation belts in four Colombian Cordilleras are presented. Operating mechanisms during Quaternary Ice-Age cycles that stimulated speciation are discussed by considering endemism in the asteraceous genera Espeletia, Espeletiopsis and Coespeletia. The floristically diverse lower montane forest belt (1000-2300 m) was compressed by ca. 55% during the last glacial maximum (LGM) (20 ka), and occupied the slopes between 800 m and 1400 m during that period. Under low LGM atmospheric pCO2 values, C4-dominated vegetation, now occurring below 2200 m, expanded up to ca. 3500 m. Present-day C3-dominated paramo vegetation is therefore not an analogue for past C4-dominated vegetation (with abundant Sporobolus lasiophyllus). Quercus immigrated into Colombia 478 ka and formed an extensive zonal forest from 330 ka when former Podocarpus-dominated forest was replaced by zonal forest with Quercus and Weinmannia. During the last glacial cycle the ecological tolerance of Quercus may have increased. In the ecotone forests Quercus was rapidly and massively replaced by Polylepis between 45 and 30 ka illustrating complex forest dynamics in the tropical Andes. PMID:15101574

  6. Recent Seismic and Geodetic Activity at Multiple Volcanoes in the Ecuadorean Andes

    NASA Astrophysics Data System (ADS)

    Hernandez, S.; Ruiz, M. C.; McCausland, W. A.; Prejean, S. G.; Mothes, P. A.; Bell, A. F.; Hidalgo, S.; Barrington, C.; Yepez, M.; Aguaiza, S.; Plain, M.

    2015-12-01

    The state of volcanic activity often fluctuates between periods of repose and unrest. The transition time between a period of repose and unrest, or vice versa for an open system, can occur within a matter of hours or days. Because of this short time scale, real-time seismic and geodetic (e.g. tiltmeter, GPS) monitoring networks are crucial for characterizing the state of activity of a volcano. In the Ecuadorean Andes, 5 volcanoes demonstrate long-term (Tungurahua, Reventador, and Guagua Pichincha) or recently reactivated (Cotopaxi, Chiles-Cerro Negro) seismic and geodetic activity. The Instituto Geofisico regularly characterizes volcano seismicity into long period, very long period, volcano-tectonic, and tremor events. Significant recent changes at these volcanoes include: rigorous reactivation of glacier-capped Cotopaxi, drumbeat seismicity absent a dome extrusion at Tungurahua, and regularly reoccurring (~7 day recurrence interval), shallow seismic swarms at Guagua Pichincha. These volcanoes locate along both the Western and Eastern Cordillera of the Ecuadorean Andes and, where data are available, manifest important variations in chemical composition, daily gas flux, and surficial deformation. We summarize the long-term geophysical parameters measured at each volcano and place recent changes in each parameter in a larger magmatic and hydrothermal context. All of the studied volcanoes present significant societal hazards to local and regional communities.

  7. Thermal physiology, disease, and amphibian declines on the eastern slopes of the Andes.

    PubMed

    Catenazzi, Alessandro; Lehr, Edgar; Vredenburg, Vance T

    2014-04-01

    Rising temperatures, a widespread consequence of climate change, have been implicated in enigmatic amphibian declines from habitats with little apparent human impact. The pathogenic fungus Batrachochytrium dendrobatidis (Bd), now widespread in Neotropical mountains, may act in synergy with climate change causing collapse in thermally stressed hosts. We measured the thermal tolerance of frogs along a wide elevational gradient in the Tropical Andes, where frog populations have collapsed. We used the difference between critical thermal maximum and the temperature a frog experiences in nature as a measure of tolerance to high temperatures. Temperature tolerance increased as elevation increased, suggesting that frogs at higher elevations may be less sensitive to rising temperatures. We tested the alternative pathogen optimal growth hypothesis that prevalence of the pathogen should decrease as temperatures fall outside the optimal range of pathogen growth. Our infection-prevalence data supported the pathogen optimal growth hypothesis because we found that prevalence of Bd increased when host temperatures matched its optimal growth range. These findings suggest that rising temperatures may not be the driver of amphibian declines in the eastern slopes of the Andes. Zoonotic outbreaks of Bd are the most parsimonious hypothesis to explain the collapse of montane amphibian faunas; but our results also reveal that lowland tropical amphibians, despite being shielded from Bd by higher temperatures, are vulnerable to climate-warming stress.

  8. Temperature and Rainfall Variability in the Northern Andes Over the Past Two Millennia

    NASA Astrophysics Data System (ADS)

    Shanahan, T. M.; Bixler, C. W.; Mora, A.

    2014-12-01

    Recent studies of tropical glaciers have shown that most are retreating rapidly, with some of the most dramatic changes occurring since the mid-1970s, most likely as a result of increasing global temperatures. However, a longer-term perspective is needed to place these changes in the context of natural climate variability. To better understand the climatological factors driving long-term variations in the mass balance of tropical glaciers, we reconstructed changes in precipitation and temperature in the northern tropical Andes using variations in the hydrogen isotope composition of sedimentary leaf waxes and branched GDGT distributions in a high-resolution varved sediment record from Lago Chingaza, Colombia. Br-GDGT derived temperatures are significantly correlated with instrumental temperature data and indicate that recent warming in the northern tropical Andes is unprecedented over the past two millennia. Furthermore, the magnitude of warming since the Little Ice Age is substantially larger than suggested by high latitude temperature reconstructions. Hydrogen isotope data indicated that colder conditions during the Little Ice Age were accompanied by a decrease in rainfall, likely associated with a southward shift in the position of the ITCZ. Over the past few centuries, warmer temperatures were accompanied by an increase in rainfall and a northward expansion of the tropical rainbelt. Together, these data suggest that the dominant control on the retreat of Andean glaciers has been the unprecedented rate and magnitude of recent warming.

  9. A new species of Telmatobius (Amphibia, Anura, Telmatobiidae) from the Pacific slopes of the Andes, Peru

    PubMed Central

    Catenazzi, Alessandro; García, Víctor Vargas; Lehr, Edgar

    2015-01-01

    Abstract We describe a new species of Telmatobius from the Pacific slopes of the Andes in central Peru. Specimens were collected at 3900 m elevation near Huaytará, Huancavelica, in the upper drainage of the Pisco river. The new species has a snout–vent length of 52.5 ± 1.1 mm (49.3–55.7 mm, n = 6) in adult females, and 48.5 mm in the single adult male. The new species has bright yellow and orange coloration ventrally and is readily distinguished from all other central Peruvian Andean species of Telmatobius but Telmatobius intermedius by having vomerine teeth but lacking premaxillary and maxillary teeth, and by its slender body shape and long legs. The new species differs from Telmatobius intermedius by its larger size, flatter head, and the absence of cutaneous keratinized spicules (present even in immature females of Telmatobius intermedius), and in males by the presence of minute, densely packed nuptial spines on dorsal and medial surfaces of thumbs (large, sparsely packed nuptial spines in Telmatobius intermedius). The hyper-arid coastal valleys of Peru generally support low species richness, particularly for groups such as aquatic breeding amphibians. The discovery of a new species in this environment, and along a major highway crossing the Andes, shows that much remains to be done to document amphibian diversity in Peru. PMID:25685025

  10. The current tectonic motion of the Northern Andes along the Algeciras Fault System in SW Colombia

    NASA Astrophysics Data System (ADS)

    Velandia, Francisco; Acosta, Jorge; Terraza, Roberto; Villegas, Henry

    2005-04-01

    Riedel, synthetic and antithetic type faults, principal displacement zones (PDZ), pull-apart basins (such as lazy-S shaped releasing bend, extensive and rhomboidal shaped and releasing sidestep basins) and minor folds located oblique to the main trace of the Algeciras Fault System (AFS) are interpreted from Landsat TM 5 images and geological mapping. These tectonic features are affecting Quaternary deposits and are related to major historical earthquakes and recent registered seismic events, indicating neotectonic activity of the structure. The AFS is classified as a right lateral wrench complex structure, with an important vertical component in which sedimentary cover and basement rocks are involved. In addition, the system represents a simple shear caused by the oblique convergence between the Nazca Plate and the northern Andes. The transpressive boundary in SW Colombia was previously located along the Eastern Frontal Fault System. However, this paper shows that the AFS constitutes the actual boundary of the current transpressive regime along the Northern Andes, which begins at the Gulf of Guayaquil in Ecuador and continues into Colombia and Venezuela.

  11. Geomorphic Response to Flat Slab Subduction along the Eastern Foothills of the Colombian Andes

    NASA Astrophysics Data System (ADS)

    Veloza, G.; Taylor, M. H.; Gosse, J. C.; Mora, A.; Becker, T. W.

    2013-12-01

    It is thought that in northwest South America flat slab subduction plays a key role in the recent development of the eastern Colombian Andes. Here we show that the geomorphic response to flat slab subduction is presently occurring >500 km inboard of the subduction zone plate boundary. The Llanos basin located along the eastern edge of the Colombian Andes is experiencing active uplift along the seismically active Cusiana, Yopal, Paz de Ariporo and Tame thrust faults, which we refer to as the Llanos Foothills thrust system (LFTS). The LFTS is comprised of east-directed thrust faults that are listric in geometry with shallowly west-dipping decollements. Locally, actively growing north-south plunging folds are cored by blind thrust faults, and are being incised by antecedent east-flowing streams. Using a combination of field-based observations on the geometry of faulted and folded fluvial terraces, and geochronology from terrestrial cosmogenic nuclides, we show that the fluvial terraces have been uplifted, and locally, incised >200 meters at incision rates exceeding 3 mm/yr. The field observations in combination with earthquakes and geodynamic simulations can be reconciled by flat slab subduction, but it is presently unknown whether the flat slab has a Caribbean or Nazca plate affinity. Different geodynamic scenarios can be tested to understand how the leading edge of the flat slab interacts with the South American craton, and how that interaction controls upper crustal deformation.

  12. Altitudinal variation in fish assemblage diversity in streams of the central Andes of Colombia.

    PubMed

    Jaramillo-Villa, U; Maldonado-Ocampo, J A; Escobar, F

    2010-06-01

    This study documents differences in fish assemblages for 32 freshwater streams located between 258 and 2242 m a.s.l. on the eastern slopes of the central range of the Colombian Andes. A total of 2049 fishes belonging to 62 species, 34 genera and 16 families were collected. Species richness declined rapidly with altitude; nearly 90% of the species were recorded between 250 and 1250 m a.s.l. Three of the four physico-chemical variables, of the water, temperature, dissolved oxygen and pH, explained 53.5% of the variation in species richness along the altitudinal gradient, with temperature the most important (37.6%). An analysis of species composition showed that the distinctiveness of the fish fauna increased with elevation, with the greatest turnover observed between 1000 and 1750 m a.s.l. On this altitudinal gradient, turnover was dominated by the loss of species rather than gain, and dominance by just a few species was greater at higher elevations. Turnover was also observed along the altitudinal gradient in the structure of the three functional groups (torrential, pool and pelagic species). The study focused on understanding the pattern of diversity of fish communities inhabiting the Andes in Colombia. Anthropogenic effects on the altitudinal distribution of fish species in the region, however, are largely unknown and would require further investigations.

  13. Seasonal Variability and Dynamics of Mesospheric Gravity Waves Over the Andes

    NASA Astrophysics Data System (ADS)

    Criddle, Neal; Taylor, Michael; Pautet, Dominique; Zhao, Yucheng

    2011-10-01

    The ALO is a new facility developed for atmospheric research, located at the foot of the Andes in Cerro Pachon, Chile (30.2 S, 70.7 W). As part of a collaborative program, Utah State has a mesospheric temperature mapper (MTM) on site, which is used to study short period gravity wave dynamics and temperature variations in the mesosphere-lower thermosphere region. The MTM began taking measurements of the OH(6,2) and O2(0,1) spectral bands in August 2009 and a complete profile of seasonal variation in gravity wave characteristics has been created for August 2009 through August 2010 using the OH(6,2) Band. The primary goal of this program is to Quantify seasonal variability of gravity wave structures. Compare and contrast seasonal directionality with results from the Maui-MALT site. Quantify mountain wave observations, their frequency, characteristics and seasonal variability. Seasonal variability for gravity wave structures at this site is shown. Mountain waves have been exclusively observed to appear in the winter months. Future work includes verifying yearly repeatability, which is seen at other sites, and continued investigation of unique events occurring over the Andes mountain range.

  14. Cranial vault modification as a cultural artifact: a comparison of the Eurasian steppes and the Andes.

    PubMed

    Torres-Rouff, C; Yablonsky, L T

    2005-01-01

    This paper details the practice of intentional cranial vault modification in the Eurasian steppes as well as in the pre-Columbian Andes focusing on the similarities and differences in how the practice was used to respond to changes in society. The appearance of vault modification in the steppes and the forms seen in the cemeteries of the Syr Darya and Amu Darya River deltas are discussed. Temporal changes in the pattern of modification are also investigated, especially the dramatic homogenization of the custom resulting from the conquests of the Huns. This is contrasted with incidences of cranial modification in the south-central Andes, including the appearance of deliberate head shaping as well as shifts in the practice during the expansion of the Bolivian Altiplano state of Tiwanaku. Similarities in the use of cranial vault modification between these unrelated areas and in the alterations of the practice resulting from foreign contact are considered in light of vault modification's role as a malleable cultural artifact.

  15. Petrofabric Interpretations Supported by Magnetic Anisotropy Observations for the Clavijo Intrusion, Colombian Andes

    NASA Astrophysics Data System (ADS)

    MacDonald, W. D.; Muggleton, S.; Estrada, J. J.; Sierra, G. M.

    2002-12-01

    Remanent magnetization studies on Late Tertiary shallow intrusions in allochthonous terranes of the Colombian Andes suggest two apparent modes of rotation, about vertical axes and about horizontal axes, as reported previously. The horizontal axes trend perpendicular to the regional structural trends, to judge by the dispersed remanence directions along vertical planes parallel to major strike-slip faults. Two distinct zones have been recognized, between Medellin and Manizales, and between Cali and Pasto (Risnes, 1995), extending approximately 600 km along the Andes. Research on the Clavijo body indicates the importance of combining studies of remanence with those of anisotropy of susceptibility (AMS) and of isothermal remanence (AIRM), and petrofabric studies, in interpreting the remanence directions in tectonically disturbed regions. In this body, hydrothermal alteration is associated with increased within-site scatter of AMS axes. Within-site remanence directions are however not dispersed by such alteration, while between-site remanence directions are affected. New results from electron-microprobe analyses of fresh and hydrothermally altered ferromagnetic (s.l.) and paramagnetic minerals are compared with the respective remanence and susceptibility anisotropies of altered and unaltered sites. A major objective is to determine if vertical flow directions in these shallow intrusions can be recognized, and thus utilized for tilt-corrections of remanence and improved tectonic interpretations. Risnes, K., 1995, Terre et Environnement, v. 2, 169 p., Dept. Mineralogy, Univ. Geneva.

  16. Modeling modern glacier response to climate changes along the Andes Cordillera: A multiscale review

    NASA Astrophysics Data System (ADS)

    Fernández, Alfonso; Mark, Bryan G.

    2016-03-01

    Here we review the literature preferentially concerned with modern glacier-climate modeling along the Andes. We find a diverse range of modeling approaches, from empirical/statistical models to relatively complex energy balance procedures. We analyzed these models at three different spatial scales. First, we review global approaches that have included the Andes. Second, we depict and analyze modeling exercises aimed at studying Andean glaciers as a whole. Our revision shows only two studies dealing with glacier modeling at this continental scale. We contend that this regional approach is increasingly necessary because it allows for connecting the "average-out" tendency of global studies to local observations or models, in order to comprehend scales of variability and heterogeneity. Third, we revise small-scale modeling, finding that the overwhelming number of studies have targeted glaciers in Patagonia. We also find that most studies use temperature-index models and that energy balance models are still not widely utilized. However, there is no clear spatial pattern of model complexity. We conclude with a discussion of both the limitations of certain approaches, as for example the use of short calibration periods for long-term modeling, and also the opportunities for improved understanding afforded by new methods and techniques, such as climatic downscaling. We also propose ways to future developments, in which observations and models can be combined to improve current understanding of volumetric glacier changes and their climate causes.

  17. Bird conservation would complement landslide prevention in the Central Andes of Colombia

    PubMed Central

    Ocampo-Peñuela, Natalia

    2015-01-01

    Conservation and restoration priorities often focus on separate ecosystem problems. Inspired by the November 11th (2011) landslide event near Manizales, and the current poor results of Colombia’s Article 111 of Law 99 of 1993 as a conservation measure in this country, we set out to prioritize conservation and restoration areas where landslide prevention would complement bird conservation in the Central Andes. This area is one of the most biodiverse places on Earth, but also one of the most threatened. Using the case of the Rio Blanco Reserve, near Manizales, we identified areas for conservation where endemic and small-range bird diversity was high, and where landslide risk was also high. We further prioritized restoration areas by overlapping these conservation priorities with a forest cover map. Restoring forests in bare areas of high landslide risk and important bird diversity yields benefits for both biodiversity and people. We developed a simple landslide susceptibility model using slope, forest cover, aspect, and stream proximity. Using publicly available bird range maps, refined by elevation, we mapped concentrations of endemic and small-range bird species. We identified 1.54 km2 of potential restoration areas in the Rio Blanco Reserve, and 886 km2 in the Central Andes region. By prioritizing these areas, we facilitate the application of Article 111 which requires local and regional governments to invest in land purchases for the conservation of watersheds. PMID:25737819

  18. Comparative Phylogeography of Direct-Developing Frogs (Anura: Craugastoridae: Pristimantis) in the Southern Andes of Colombia

    PubMed Central

    García-R, Juan C.; Crawford, Andrew J.; Mendoza, Ángela María; Ospina, Oscar; Cardenas, Heiber; Castro, Fernando

    2012-01-01

    The Andes of South America hosts perhaps the highest amphibian species diversity in the world, and a sizable component of that diversity is comprised of direct-developing frogs of the genus Pristimantis (Anura: Craugastoridae). In order to better understand the initial stages of species formation in these frogs, this study quantified local-scale spatial genetic structuring in three species of Pristimantis. DNA sequences of two mitochondrial gene fragments (16S and COI) were obtained from P. brevifrons, P. palmeri and P. jubatus at different locations in the Cordillera Occidental. We found high levels of genetic diversity in the three species, with highly structured populations (as measured by FST) in P. brevifrons and P. palmeri while P. jubatus showed panmixia. Large effective population sizes, inferred from the high levels of genetic diversity, were found in the three species and two highly divergent lineages were detected within P. jubatus and P. palmeri. Estimated divergence times among populations within P. brevifrons and P. palmeri coincide with the Pleistocene, perhaps due to similar responses to climatic cycling or recent geological history. Such insights have important implications for linking alpha and beta diversity, suggesting regional scale patterns may be associated with local scale processes in promoting differentiation among populations in the Andes. PMID:23049941

  19. Monitoring environmental change in the Andes based on low resolution time series analysis

    NASA Astrophysics Data System (ADS)

    Tote, C.; Swinnen, E.; Beringhs, K.; Govers, G.

    2012-04-01

    Environmental change is an important issue in the Andes region and it is unknown to what extent the ongoing processes are a consequence of human impact and/or climate change. The objectives of this research are to study vegetation dynamics in the Andes region based on time series analysis of SPOT-Vegetation, NOAA-AVHRR and MODIS derived NDVI at low spatial but high temporal resolution, and to recognize to which extent this variability can be attributed to either climatic variability or human induced impacts through assimilation of satellite derived NDVI and rainfall data. Monthly rainfall estimates were available from the European Centre for Medium-Range Weather Forecasts (ECMWF) through MeteoConsult and the Monitoring Agricultural ResourceS (MARS) unit. Deviations from the 'average' situation were calculated for the NDVI time series using the Standardized Difference Vegetation Index (SDVI) and for the precipitation time series using the Standardized Precipitation Index (SPI). Correlation analysis between NDVI and SPI is performed in order to identify the temporal scale at which the environment is most sensitive to precipitation anomalies (best lag). Trends in SDVI and SPI are investigated using least square regression, taking into account the accumulated rainfall anomalies over the best lag. Hot spots of human induced environmental change are detected by subtraction of the precipitation induced signal on vegetation dynamics. The model can be used to predict possible effects of climate change in areas most sensible to trends in precipitation.

  20. Thermal physiology, disease, and amphibian declines on the eastern slopes of the Andes.

    PubMed

    Catenazzi, Alessandro; Lehr, Edgar; Vredenburg, Vance T

    2014-04-01

    Rising temperatures, a widespread consequence of climate change, have been implicated in enigmatic amphibian declines from habitats with little apparent human impact. The pathogenic fungus Batrachochytrium dendrobatidis (Bd), now widespread in Neotropical mountains, may act in synergy with climate change causing collapse in thermally stressed hosts. We measured the thermal tolerance of frogs along a wide elevational gradient in the Tropical Andes, where frog populations have collapsed. We used the difference between critical thermal maximum and the temperature a frog experiences in nature as a measure of tolerance to high temperatures. Temperature tolerance increased as elevation increased, suggesting that frogs at higher elevations may be less sensitive to rising temperatures. We tested the alternative pathogen optimal growth hypothesis that prevalence of the pathogen should decrease as temperatures fall outside the optimal range of pathogen growth. Our infection-prevalence data supported the pathogen optimal growth hypothesis because we found that prevalence of Bd increased when host temperatures matched its optimal growth range. These findings suggest that rising temperatures may not be the driver of amphibian declines in the eastern slopes of the Andes. Zoonotic outbreaks of Bd are the most parsimonious hypothesis to explain the collapse of montane amphibian faunas; but our results also reveal that lowland tropical amphibians, despite being shielded from Bd by higher temperatures, are vulnerable to climate-warming stress. PMID:24372791

  1. Intraseasonal variability of organized convective systems in the Central Andes: Relationship to Regional Dynamical Features

    NASA Astrophysics Data System (ADS)

    Mohr, K. I.; Slayback, D. A.; Nicholls, S.; Yager, K.

    2013-12-01

    The Andes extend from the west coast of Colombia (10N) to the southern tip of Chile (53S). In southern Peru and Bolivia, the Central Andes is split into separate eastern and western cordilleras, with a high plateau (≥ 3000 m), the Altiplano, between them. Because 90% of the Earth's tropical mountain glaciers are located in the Central Andes, our study focuses on this region, defining its zonal extent as 7S-21S and the meridional extent as the terrain 1000 m and greater. Although intense convection occurs during the wet season in the Altiplano, it is not included in the lists of regions with frequent or the most intense convection. The scarcity of in-situ observations with sufficient density and temporal resolution to resolve individual storms or even mesoscale-organized cloud systems and documented biases in microwave-based rainfall products in poorly gauged mountainous regions have impeded the development of an extensive literature on convection and convective systems in this region. With the tropical glaciers receding at unprecedented rates, leaving seasonal precipitation as an increasingly important input to the water balance in alpine valley ecosystems and streams, understanding the nature and characteristics of the seasonal precipitation becomes increasingly important for the rural economies in this region. Previous work in analyzing precipitation in the Central Andes has emphasized interannual variability with respect to ENSO, this is the first study to focus on shorter scale variability with respect to organized convection. The present study took advantage of the University of Utah's Precipitation Features database compiled from 14 years of TRMM observations (1998-2012), supplemented by field observations of rainfall and streamflow, historical gauge data, and long-term WRF-simulations, to analyze the intraseasonal variability of precipitating systems and their relationship regional dynamical features such as the Bolivian High. Through time series and

  2. Influence of Leaf Chemical Composition on Bacterial and Fungal Colonization During Leaf Litter Decomposition in a Venezuelan stream

    NASA Astrophysics Data System (ADS)

    Rincon, J.

    2005-05-01

    We studied bacterial and fungal colonization during decomposition of leaf litter differing in chemical composition in a small intermittent stream of northwestern Venezuela. Litter bags containing leaves of Tabebuia roseae, Ficus sp, Hura crepitans and Anacardium excelsum were incubated during 42 days in the stream. Six bags were retrieved after 2, 7, 14, 21, 28, 35 and 42 days and the mass loss was registered. Leaves were initially analyzed for N, P, Lignin and Polyphenols in order to assess the chemical composition of each species. Conidia of aquatic hyphomycetes were identified and quantified after in vitro incubation of leaves with filtered stream water. Bacteria were counted and identified using an epifluorescence microscope. The species H. crepitans and Ficus sp showed higher decomposition rates than T. roseae and A. excelsum. Higher conidia production was observed in Anacardium leaves, while bacterial density and biomass resulted higher in Hura leaves. Our results suggest that chemical composition of leaves differentially affected to bacteria and aquatic hyphomicetes colonization. Bacteria colonized earlier than fungi during leaf litter decomposition process.

  3. Late Pleistocene glaciations of the arid subtropical Andes and new results from the Chajnantor Plateau, northern Chile

    NASA Astrophysics Data System (ADS)

    Ward, Dylan J.; Cesta, Jason M.; Galewsky, Joseph; Sagredo, Esteban

    2015-11-01

    The spatiotemporal pattern of glaciation along the Andes Mountains is an important proxy record reflecting the varying influence of global and regional circulation features on South American climate. However, the timing and extent of glaciation in key parts of the orogen, particularly the deglaciated arid Andes, are poorly constrained. We present new cosmogenic 10Be and 36Cl exposure ages for glacial features on and near the Chajnantor Plateau (23 °S). The new dates, although scattered due to cosmogenic inheritance, imply that the most recent extensive glacial occupation ended before or during the global Last Glacial Maximum (LGM). We discuss this new record in the context of published glacial chronologies from glacial features in Peru, Bolivia, and northern Chile rescaled using the latest cosmogenic 10Be production rate calibration for the tropical Andes. The results imply regionally synchronous moraine stabilization ca. 25-40 ka, 15-17 ka, and 12-14 ka, with the youngest of these moraines absent in records south of ˜20 °S, including in our new Chajnantor area chronology. This spatial pattern implicates easterly moisture in generating sufficient snowfall to glaciate the driest parts of the Andes, while allowing a role for westerly moisture, possibly modulated by the migration of the Southern Westerly Wind belt, in the regions near and south of the Atacama Desert.

  4. An Ancestral Language to Speak with the "Other": Closing down Ideological Spaces of a Language Policy in the Peruvian Andes

    ERIC Educational Resources Information Center

    Zavala, Virginia

    2014-01-01

    Using a multilayered, ethnographic and critical approach to language policy and planning, this article examines a language policy favoring Quechua in Apurímac in the Southern Peruvian Andes, which is being imagined as an integrated community unified by the local language. This study presents a case in which top-down policies open up ideological…

  5. A new species of Eretris Thieme (Lepidoptera: Nymphalidae, Satyrinae) from the Elbow of the Andes region in Bolivia.

    PubMed

    Pyrcz, Tomasz W; Gareca, Yuvinka

    2009-01-01

    A new species of cloud forest butterfly, Eretris julieta n. sp. is described from a region of south-central Bolivia known as the Elbow of the Andes. It is the southernmost known representative of the genus, hitherto known only from a restricted area of interandean valleys in the department of Santa Cruz. Its affinities with other congeners are evaluated.

  6. Spatial variability of snow physical properties across northwestern Greenland

    NASA Astrophysics Data System (ADS)

    Courville, Z.; Polashenski, C.; Dibb, J. E.; Domine, F.

    2013-12-01

    In the late spring and early summer of 2013, researchers on the SAGE (Sunlight Absorption on the Greenland ice sheet Experiment) Traverse, embarked on a 4000 km ground traverse across northwestern Greenland in an attempt to quantify spatial variability of snow chemistry, snow physical properties, and snow reflectance. The field team targeted sites first visited by Carl Benson during his series of traverses from 1952 to 1955 as part of his pioneering work to characterize the Greenland Ice Sheet. This route now represents a rapidly changing and variable area of Greenland, as the route passes through several of the ice sheet facies first delimited by Benson. Along the traverse, the SAGE field team made ground-based albedo measurements using a hand-held spectroradiometer and collected snow physical property samples to determine snow specific surface area (SSA) from shallow, 2m pits. In addition, snow density and stratigraphy were measured. Snow layers in the near-surface and at the previous season's melt layer were targeted for sampling. Here we present preliminary snow physical property results from the upper portion of the snow pits and relate these to surface albedo data collected over the route. Further measurements of snow properties in the 2012 melt layer will be analyzed to assess the potential role of snow chemical (see Dibb et al. for a discussion of chemical analysis) and physical property driven albedo feedbacks could have played in contributing to that event. Route of 2013 SAGE Traverse in northwestern Greenland.

  7. Molecular Diversity of Mycobacterium tuberculosis Strains in Northwestern Iran

    PubMed Central

    Pourostadi, Mahya; Rashedi, Jalil; Mahdavi Poor, Behroz; Samadi Kafil, Hossein; Shirazi, Samaneh; Asgharzadeh, Mohammad

    2016-01-01

    Background Years after the development of antituberculosis (TB) drugs, many people continue to suffer from this disease. To control the spread of TB, strains of the Mycobacterium tuberculosis complex need to be determined, and sources of infection must be identified. Such steps should help to prevent transmission of the infection. Objectives The aim of this study was to perform molecular genotyping of isolates of the M. tuberculosis complex obtained from patients in northwestern Iran. Methods One hundred ninety-four culture-positive M. tuberculosis isolates obtained from patients in northwestern Iran were analyzed using the mycobacterial interspersed repetitive unit-exact tandem repeats (MIRU-ETR) method. Results The MIRU-ETR method distinguished 162 different patterns in the 194 isolates, comprising 23 clusters and 139 unique patterns. Its discriminatory power according to the Hunter-Gaston discriminatory index (HGDI) was 0.9978. The largest cluster contained six isolates. Conclusions This research indicated that various strains of M. tuberculosis were responsible for TB and that the majority of cases were due to reactivation. PMID:27800145

  8. Numerical study of a downslope windstorm in Northwestern Greece

    NASA Astrophysics Data System (ADS)

    Koletsis, I.; Lagouvardos, K.; Kotroni, V.; Bartzokas, A.

    2009-10-01

    This paper describes the leeside wind storm of 25-26 March 1998, the most intense wind storm of the last decade in Northwestern Greece. This wind storm produced wind gusts of ˜ 30 m s - 1 that resulted in tree uprooting, roof damaging, electric power network disruption and flooding in the lake-side areas of Ioannina city in Northwestern Greece. With the aim to identify the role of Mountain Mitsikeli near the city of Ioannina on the windstorm and to investigate the physical mechanisms responsible for such orographically induced weather events, numerical simulations with MM5 model have been performed. The model results showed that a resolution of 2-km resolution is necessary in order to reproduce the localized character of the wind storm. The analysis revealed that a synergistic combination of the cross-barrier northeasterly flow, the stable layer above the mountain top and the presence of a critical level, led to the intensification of the lee side winds during the studied wind event. Sensitivity experiments with modified topography, further supported the important role of mountain Mitsikeli that stands as an isolated obstacle, on the modification of the wind field during the observed windstorm.

  9. Incidence of the major Brassica pests in northwestern Spain.

    PubMed

    Cartea, M E; Padilla, G; Vilar, M; Velasco, P

    2009-04-01

    Kale (Brassica oleracea L. acephala group) crops are common in northwestern Spain, where they are severely damaged by different insect pests. The damage notably affects the value of this crop because it is freshly consumed and fresh processed. The objective of this work was to determine the abundance and relative importance of the main Lepidoptera pests of Brassica crops for 6 yr at five localities in northwestern Spain and to relate the seasonal changes of larval populations and environmental conditions. Pheromone traps were used as a method of monitoring adults. Larval populations were monitored on kales by counting the larvae for several years and locations at different sample dates. Five species were found: Mamestra brassicae (L.); imported cabbageworm, Pieris rapae (L.); Pieris brassicae (L.); diamondback moth, Plutella xyllostella (L.); and Autographa gamma L. Proportions of each insect fluctuated over the years and in the different locations. M. brassicae was the most abundant (48.5% of the total of Lepidoptera species) followed by P. xyllostella (25%) and P. rapae (15%). The use of pheromone traps combined with plant sampling permitted the detection of two generations of M. brassicae. However, adult counts were not correlated to the number of larvae on plants. PMID:19449659

  10. Acute rheumatic fever in First Nations communities in northwestern Ontario

    PubMed Central

    Gordon, Janet; Kirlew, Mike; Schreiber, Yoko; Saginur, Raphael; Bocking, Natalie; Blakelock, Brittany; Haavaldsrud, Michelle; Kennedy, Christine; Farrell, Terri; Douglas, Lloyd; Kelly, Len

    2015-01-01

    Abstract Objective To document a case series of 8 young First Nations patients diagnosed with acute rheumatic fever (ARF), a preventable disease that resulted in the death of 2 patients, in northwestern Ontario in the context of late diagnosis, overcrowded housing, and inadequate public health response. Design Retrospective case series over an 18-month period. Setting Remote First Nations communities in northwestern Ontario. Participants Eight patients with ARF. Main outcome measures Incidence, mortality, residual rheumatic heart disease, time to diagnosis, barriers to diagnosis and treatment, housing situation of patients, patient demographic characteristics (age, sex), and investigation results. Results The incidence of ARF in this population was 21.3 per 100 000, which is 75 times greater than the overall Canadian estimated incidence. The average patient age was 9.4 years. Most cases developed joint findings, and 5 of the surviving patients had rheumatic heart disease when they received echocardiography. The average time to diagnosis was 88 days. Two 4-year-old children died from ARF. Most patients lived in inadequate and crowded housing. Conclusion This rare disease still exists in remote First Nations communities. These communities demonstrate an incidence equal to that in aboriginal communities in Australia and New Zealand, which have among the highest international incidence of ARF. Primordial prevention, including improved on-reserve housing, is urgently needed. Case detection and ongoing surveillance for primary and secondary prophylaxis requires a well resourced regional strategy. PMID:26759842

  11. Tectonic Implications of Paleoproterozoic Deo Khe Granitoids in Northwestern Vietnam

    NASA Astrophysics Data System (ADS)

    Hoang, T. H. A.; Yu, Y.; Pham, T. H.; Choi, S. H.; Tu, V. L.; Son, L. M.

    2015-12-01

    An integrated study of petrographic description, zircon U/Pb geochronology, and Hf isotopic analysis was carried out on the medium-grained two-mica Deo Khe Granitoids (DKG) in northwestern Vietnam. U/Pb zircon ages were 1855-1873 Ma, interpreted as the time of magma crystallization. On the basis of Hf isotopic compositions, a single-stage Hf model ages were estimated as 3.3-2.8 Ga. Values of Hf isotopes ɛHf (t) range from -23.6 to -17.5, suggesting that the DKG are products of reworked Archean crustal rocks. A similar sequence of tectonic events including the presence of 2.8-2.9 Ga tonalite-trondhjemite-granodiorite (TTG) gneiss, metamorphic development of TTG gneiss at 1.9-2.0 Ga, and 1.85 Ga magmatic activity were recognized both in Yangtze block and northwestern Vietnam. Therefore we propose that basement rocks in northern Vietnam are similar to those found along southern China.

  12. Prevalence of anemia in First Nations children of northwestern Ontario.

    PubMed Central

    Whalen, E. A.; Caulfield, L. E.; Harris, S. B.

    1997-01-01

    OBJECTIVE: To estimate the prevalence of anemia among First Nations children of northwestern Ontario. DESIGN: Retrospective review of all hemoglobin determinations between 1990 and 1992 in the Sioux Lookout Zone. SETTING: The Sioux Lookout Zone Hospital, a secondary care referral hospital for 28 remote First Nations communities in northwestern Ontario, affiliated with the University of Toronto's Sioux Lookout Program. PARTICIPANTS: All First Nations children age 3 to 60 months who had produced venipuncture or fingerprick blood samples between 1990 and 1992 (614 children had a total of 1223 hemoglobin determinations). MAIN OUTCOME MEASURES: Prevalence of anemia by age, sex, geographical location, and diagnosis. Anemia was defined as a hemoglobin value less than 110g/L. RESULTS: Prevalence of anemia peaked in the age range of 6 to 24 months with prevalence rates of 51.7% to 79.3%. Conditions most commonly associated with anemia were respiratory tract infections. Children living in communities in the western part of the Sioux Lookout Zone were 1.64 times more likely to have anemia (95% confidence interval 1.15, 2.35) than children in the other communities. CONCLUSIONS: Anemia appears to be a serious public health problem among preschool children in the Sioux Lookout Zone. PMID:9111982

  13. Crustal Thickness in Northern Andes Using pP and sS Precursors at Teleseismic Distances

    NASA Astrophysics Data System (ADS)

    Aranda Camacho, N. M.; Assumpcao, M.

    2013-12-01

    The Andean belt is a result of the subduction of the Nazca plate beneath the South American continental plate. It has an extension of 8000 km from Venezuela to Tierra del Fuego. While the crustal-thickness is a well-known property in Southern and Central Andes, it is still poorly known in the Northern Andes (between 10°N and 4° S). The crustal thickness is a very important property to understand the crustal evolution such as in geodynamic models and in modeling wave-propagation in global and regional seismic studies. Due to the high seismic activity at intermediate depths in the Northern Andes, it is possible to use the teleseismic P-wave and S-wave trains to find the crustal-thickness. In this study, we analyze the reflections from the underside of the Moho for intermediate and deep earthquakes in the northern Andes recorded at teleseismic distances (between 40°- 85°), and estimate the crustal-thickness at the bounce points of the pP and sS wave by converting the delay time between the phases pP and pmP and also between sS and smS into crustal thickness. This method can be applied in zones with earthquakes having magnitude larger than 6 for that reason the Northern Andes is a favorable area to develop it. We analyzed five events from the Northern Andes with magnitude larger than 6 and deeper than 100 km. The crustal thickness was calculated using the P wave with the vertical component and the S wave using both transverse SH and radial SV components. We find that the crustal-thickness in this area varied from 27.9 × 2.4 km at (76.48 W, 4.82 N) to 55.7 × 5.2 km at (77.92 W, 2 S). Our results show a crustal-thickness consistent with a compilation made for a larger region that includes our research area, showing residuals between -4 km and 4 km in most of the bounce points . We are getting results in areas that have not been studied previously so it will help to increase the database of crustal-thicknesses for the Northern Andes.

  14. Modelling increased landslide susceptibility near highways in the Andes of southern Ecuador

    NASA Astrophysics Data System (ADS)

    Brenning, Alexander; Muenchow, Jannes

    2016-04-01

    Modelling increased landslide susceptibility near highways in the Andes of southern Ecuador A. Brenning (1), J. Muenchow (1) (1) Department of Geography, Friedrich Schiller University Jena, Loebdergraben 32, 07743 Jena, Germany Mountain roads are affected by and also affect themselves landslide suceptibility. Especially in developing countries, inadequate drainage systems and mechanical destabilization of hillslopes by undercutting and overloading are known processes through which road construction and maintenance can enhance landslide activity within the immediate surroundings of road infrastructure. In the Andes of southern Ecuador, strong precipitation gradients as well as lithological differences provide an excellent study site in which the relationship between highways and landslide susceptibility and its regional differentiation can be studied. This study uses Generalized Additive Models (GAM) to investigate patterns of landslide susceptibility along two paved interurban highways in the tropical Andes of southern Ecuador. The relationship of landslides to distance from road is modeled while accounting for topographic, climatic and lithological predictors as possible confounders and modifiers, focusing on the odds ratio of landslide occurrence at 25 m versus 200 m distance from the highway. Spatial attention is given to uncertainties in estimated odds ratios of landslide occurrence using spatial block bootstrap techniques. The GAM is able to represent nonlinear additive terms as well as bivariate smooth interaction terms, providing a good tradeoff between model complexity and interpretability. The estimated odds of landslide occurrence were 18-21 times higher near the highway than at 200 m distance, based on different analyses, with lower 95% confidence limits always >13. (Semi-) parametric estimates confirmed this general range of values but suggests slightly higher odds ratios (95% confidence interval: 15.5-25.3). Highway-related effects were observed to

  15. What controls millennial-scale denudation rates across the Central Andes?

    NASA Astrophysics Data System (ADS)

    Zeilinger, Gerold; Korup, Oliver; Schlunegger, Fritz; Kober, Florian

    2015-04-01

    Sustainable planning of erosion control measures in the Central Andes requires robust knowledge about natural denudation rates. We explore a large dataset combining new and published 10Be (and 26Al) catchment-wide denudation rates from a swath at 17 to 19° S spanning the Western Cordillera that rises from sea level to 5500 m elevation; the Altiplano at ~4000 m; the Eastern Cordillera with elevations up to 6500 m; the Interandean Zone; the Subandean Zone; and the Chaco Plain at 300 m. The selected catchments span a large spread regarding morphometric and climate properties where mean slope angles range from 1 to 31°, and mean precipitation from 100 to 3900 mm/a. The denudation rates (0.0036 to 1.93 mm/a) are averaged over millennia, and reveal two to three magnitudes difference across the Central Andes. The regional distribution of denudation rates clearly demonstrates a more complex interaction of geomorphological, geological and meteorological parameters with the dominant geomorphological processes. In order to elucidate the key controls on denudation, we use multivariate statistics such as principal component analysis in order to remove potentially redundant predictors of denudation in the studied catchments. These predictors include catchment elevation, topographic relief, hillslope inclination, mean precipitation, tree cover, specific stream power, channel steepness indices, sinuosity, drainage density and hypsometric index that we derived from the SRTM 90 m Digital Elevation Database, the Tropical Rainfall Measuring Mission (TRMM) data, and the Terra MODIS Vegetation Continuous Fields dataset. Additionally, the rock strength index (PLI) was estimated based on geological units. Preliminary results allow distinguishing five different longitudinal domains of denudation on the basis of climatic regime, hillslope steepness, and the degree of accumulated crustal deformation. We find that the pattern of 10Be catchment-wide denudation rates in the Central Andes

  16. Prediction of glacier melt and runoff for a high-altitude headwater catchment in Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Liu, T.; Kinouchi, T.; Mendoza, J.; Asaoka, Y.

    2013-12-01

    In Andes, retreat of tropical glaciers is rapid, thus water resources currently available from glacierized catchments would be changed in its volume and temporal variations due to climate change and glacier shrinkage. Water resources in La Paz and El Alto, Bolivia, strongly depend on the runoff from glacierized headwater catchments in the Cordillera Real, Andes, which is a combined contribution from glacier and snow melts in glacierized areas and surface and subsurface runoff due to snowmelt and rainfall in non-glacierized areas. To predict long-term availability of water resources from glacierized catchments in the Cordillera Real, we developed a semi-distributed conceptual glacio-hydrological model applicable for the partially glacierized catchments in high mountains by considering different phases of precipitation, various runoff components from glacierized and non-glacierized areas, the retarding effect by lakes and wetlands, and the change of glacierized areas based on the area-volume relationship. The model was successfully applied to the Huayna West headwater catchment located in the Cordillera Real, Bolivian Andes, for the period of June 2011 to May 2013, after calibrating by observed meteorological and hydrological conditions. Our results indicate that the glacier melt is enhanced during two transition periods, i.e. from the dry to wet season (October to early December) and the wet to dry season (March to May), while the surface runoff from snowmelt and subsurface runoff are more dominant between the two periods from December to February. It was found that the simulated runoff was highly sensible to spatial and temporal variation of air temperature, and smoothed by the subsurface flow and retarding processes in lakes and wetlands. We predicted the change of glacierized area and runoff until 2050 under different climate scenarios, which indicates that the glacier continues to shrink by 2050 resulting in the areal reduction ranging from 65% to 73% and

  17. Cosmogenic Nuclide Studies And Geomorphological Implications In The Hyperarid Central Western Andes, Northern Chile

    NASA Astrophysics Data System (ADS)

    Kober, F.; Schlunegger, F.; Ivy-Ochs, S.; Baur, H.; Wieler, R.; Kubik, P. W.; Schneider, H.

    2003-12-01

    We have conducted geomorphological and cosmogenic nuclide studies in the central Andes of Northern Chile (Arica area) in order to quantify landscape evolution at the Western Andean Escarpment. The area is characterized by broad abandoned middle to late Miocene plains that are cut by deeply incised rivers. The major phase of incision has been active since ca. 8 My with different magnitudes and accelerated backward erosion forces through time. Important processes must have been a base level change in the Coastal Cordillera area and climatic changes driven by orogenic growth. Fluvial incision rates are ca. 50m/My across the Escarpment during the middle/late Miocene and early Pliocene and about two to four times higher from the Pliocene until the present, especially in more distal parts relative to the pinned base level control (enhanced backward erosion). Bedrock erosion rates on the broad plains determined with cosmogenic nuclides are several orders of magnitude lower than fluvial incision rates. Erosion rates of ignimbrites determined by paired studies of radionuclides (10Be, 26Al) and stable 21Ne are 10 to 100cm/My at medium elevations and increase towards the high Andes to >250cm/My. This increase is largely controlled by the effect of orographic precipitation that correlates with increasing rates and intensities of rainfall towards the Western Cordillera. Coastal areas, subjected only to coastal fog, show abandoned hanging rivers and smoothed diffusive hillslopes. These landscapes exhibit also extremely low cosmogenically derived erosion rates (<100cm/My). Therefore, the large parts of the landscapes at the northern tip of the Atacama Desert have retained their relict landscape aspect since they formed in Middle Micocene. The comparison of river incision and bedrock erosion clearly shows a strong decoupling between both geomorphic landscape units. A change towards a coupled system can only be found in the high, rainy parts of the Andes (>3500m), which are

  18. Cold Episodes, Their Precursors and Teleconnections in the Central Peruvian Andes (1958-2009)

    NASA Astrophysics Data System (ADS)

    Sulca, J. C.; Vuille, M. F.; Trasmonte, G.; Silva, Y.; Takahashi, K.

    2014-12-01

    The Mantaro valley (MV) is located in the central Peruvian Andes. Occasionally, cold episodes are observed during the austral summer (January-March), which strongly damage crops. However, little is known about the causes and impacts of such cold episodes in the MV. The main goal of this study is thus to characterize cold episodes in the MV and assess their large-scale circulation and teleconnections over South America (SA) during austral summer. To identify cold events in the MV daily minimum temperature for the period 1958-2009 from Huayao station, located within the MV was used. We defined a cold episode as the period when daily minimum temperature drops below the 10-percentile for at least one day. Several gridded reanalysis and satellite products were used to characterize the large-scale circulation, cloud cover and rainfall over SA associated with these events for same period. Cold episodes in the MV are associated with positive OLR anomalies, which extend over much of the central Andes, indicating reduced convective cloud cover during these extremes, but also affirm the large-scale nature of these events. At the same time, northeastern Brazil (NEB) registers negative OLR anomalies, strong convective activity and enhanced cloud cover because displacement of the South Atlantic Convergence Zone (SACZ) toward the northeast of its climatologic position. Further, it is associated with a weakening of the Bolivian High - Nordeste Low (BH-NL) system at upper levels, but also influenced by a low-level migratory high-pressure center develops at 30°S, 50°W; propagating from mid- to low latitudes as part of an extratropical Rossby wave train. In conclusion, cold episodes in the MV appear to be caused by radiative cooling associated with reduced cloudiness, rather than cold air advection. The reduced cloud cover in turn results from a robust large-scale pattern of westerly wind anomalies over central Peruvian Andes, inhibiting moisture influx, convective activity and

  19. The Andes as a peripheral orogen of the breaking-up Pangea

    NASA Astrophysics Data System (ADS)

    Lomize, M. G.

    2008-05-01

    Formation conditions of the peripheral orogen are expressed most fully in the Central Andes, a mountain system almost not yielding in height to the Himalayan-Tibetan system but formed at the margin of ocean without any relations to intercontinental collision. The marine transgression and rejuvenation of subduction in the Early Jurassic during the origination of foldbelt at the margin of Pangea marked the transition to a new supercontinental cycle, and the overall further evolution began and continues now in the frame of the first half of this cycle. The marginal position of this belt above the subduction zone, the rate and orientation of convergence of the lithospheric plates, the age of “absolute” movement of the continental plate, variation in slab velocity, and subduction of heterogeneities of the oceanic crust were the crucial factors that controlled the evolution of the marginal foldbelt. At the stage of initial subsidence (Jurassic-Mid-Cretaceous), during extension of the crust having a moderate thickness (30-35 km), the Andean continental margin comprises the full structural elements of an ensialic island arc that resembled the present-day Sunda system. These conditions changed with the separation and onset of the western drift of the South American continent. Being anchored in the mantle and relatively young, the slab of the Andean subduction zone served as a stop that brought about compression that controlled the subsequent evolution. Due to the contribution of deep magma sources along with marine sediments and products of tectonic erosion removed to a depth, the growth of crust above the subduction zone was favorable for heating of the crust. By the middle Eocene, when compression enhanced owing to the acceleration of subduction, the thermal evolution of the crust had already prepared the transition to the orogenic stage of evolution, i.e., to the progressive viscoplastic shortening and swelling of the mechanically weakened lower crust and the

  20. Examining a Half Century of Northwestern North American Glacier Behavior

    NASA Astrophysics Data System (ADS)

    Molnia, B. F.; Fahey, M. J.; Friesen, B.; Josberger, E. G.

    2015-12-01

    In 1957, as part of the United States' contribution to the International Geophysical Year (IGY), the American Geographical Society (AGS) initiated a multi-institutional mapping project to produce 1:10,000-scale topographic maps of nine northwestern North American glaciers. The project's goal was to prepare precise maps at large scales of selected small glaciers to form a permanent record of the condition of these glaciers so that at a future date they could be resurveyed and compared. Continued surveys would give the history of wastage and accumulation, and more accurate interpretation of the response of these glaciers to meteorological and other factors. The resulting maps and a descriptive summary brochure were published in 1960 by the American Geographical Society. The USGS Global Fiducials Program (GFP) began to systematically image the same nine glaciers approximately half-century after its IGY mapping. The results of the GFP analyses would permit the types of comparisons that were envisioned by the IGY project. Imagery of each of these nine glaciers has been collected from multiple sources, including Next View licensed commercial imagery, vertical and oblique aerial photography, Landsat, and US National Imagery Systems. Exploitation of the imagery has resulted in the production of new 21st century maps that can be compared and contrasted with the vintage AGS map set. Comparison will permit the calculation of a number of parameters which will provide a direct insight into the changes that northwestern North American glaciers have been experiencing during the past half century. Specifically, these comparisons will permit the calculation of changes in glacier length, area, thickness, and volume; computation of rates of glacier advance and/or retreat, rates of glacier thickening and/or thinning, and rates of volume change; production of digital elevation models (DEMs); and generation of velocity fields from crevasse migration. The subsequent re-mapping and

  1. Morphometric features as tribal predictors in north-western Amazonia.

    PubMed

    Milton, K

    1983-01-01

    Multivariate analyses of variance were carried out on stature and weight of 50 adults (25 males, 25 females) from each of two linguistically distinct groups, Maku and Tukanoan, living sympatrically in north-western Amazonia. Results showed significant intertribal differences, with Maku (sylvan hunter-gatherers) being both shorter and lighter than their Tukanoan (riparian fisher-gardeners) conspecifics. Classification with a linear discrimination function achieved 80% accuracy. Stature or weight were equally good predictors of group for men, but for women weight rather than stature was a more powerful predictor. These data offer support for the view that some factor(s) associated with life within the equatorial forest environment appear to select for generally small body physique in humans. PMID:6638939

  2. Northwestern Pacific typhoon intensity controlled by changes in ocean temperatures

    PubMed Central

    Mei, Wei; Xie, Shang-Ping; Primeau, François; McWilliams, James C.; Pasquero, Claudia

    2015-01-01

    Dominant climatic factors controlling the lifetime peak intensity of typhoons are determined from six decades of Pacific typhoon data. We find that upper ocean temperatures in the low-latitude northwestern Pacific (LLNWP) and sea surface temperatures in the central equatorial Pacific control the seasonal average lifetime peak intensity by setting the rate and duration of typhoon intensification, respectively. An anomalously strong LLNWP upper ocean warming has favored increased intensification rates and led to unprecedentedly high average typhoon intensity during the recent global warming hiatus period, despite a reduction in intensification duration tied to the central equatorial Pacific surface cooling. Continued LLNWP upper ocean warming as predicted under a moderate [that is, Representative Concentration Pathway (RCP) 4.5] climate change scenario is expected to further increase the average typhoon intensity by an additional 14% by 2100. PMID:26601179

  3. Seismic and chronostratigraphic results from SHALDRIL II, northwestern Weddell Sea

    USGS Publications Warehouse

    Anderson, J.B.; Wellner, J.; Wise, S.; Bohaty, S.; Manley, P.; Smith, T.; Weaver, F.; Kulhanek, D.

    2007-01-01

    The 2006 SHALDRIL II cruise was conducted in the northwestern Weddell Sea, with primary drilling targets in the James Ross Basin. A site drilled along the northern edge of the James Ross Basin sampled either latest Eocene or earliest Oligocene deposits, providing a lower chronostratigraphic benchmark for our seismic stratigraphic age model. Severe sea ice conditions forced abandonment of several of the James Ross Basin sites. Three alternate sites were drilled along the southern flank of the Joinville Plateau. Seismic data from the area show a thick, southward dipping stratigraphic succession with no conspicuous gaps. Three drill sites sampled this succession and recovered Oligocene, middle Miocene, and early Pliocene strata overlain by a thin drape of Pleistocene deposits. The Pliocene-Miocene boundary appears to be represented by a disconformity within the cored interval. Otherwise, this is one of the most complete post-Eocene successions anywhere on Antarctica and its adjacent margins

  4. The use of photovoltaics for rural electrification in northwestern China

    SciTech Connect

    Wallace, W.L.; Li Jingming; Gao Shangbin

    1998-09-01

    The use of renewable energy technologies in China is becoming increasingly important to meet the needs of a large rural population. Solar and wind renewable resources in particular are available in regions of China that at present have no access to conventional grid power. Two regions in China that have an acute lack of electricity are a large region in northern and western China and the coastal island region of China. These regions have attracted the attention of the Chinese government in terms of increasing the quality of life and standard of living conditions of the rural population. These regions have also attracted the attention of domestic Chinese companies and of international companies, governments, and multilateral development organizations as a potential market for renewable energy rural electrification systems. This paper focuses on the bilateral cooperation between the US Department of Energy and China in providing assistance for the use of renewable technologies for rural electrification in northwestern China.

  5. Intoxication of nontarget wildlife with rodenticides in northwestern Kansas.

    PubMed

    Ruder, Mark G; Poppenga, Robert H; Bryan, John A; Bain, Matt; Pitman, Jim; Keel, M Kevin

    2011-01-01

    The perception of prairie dogs (Cynomys spp.) both as a nuisance species and a keystone species presents a significant challenge to land, livestock, and wildlife managers. Anticoagulant and nonanticoagulant rodenticides are commonly employed to control prairie dog populations throughout their range. Chlorophacinone, and to a lesser extent zinc phosphide, are widely used in northwestern Kansas for controlling black-tailed prairie dog (Cynomys ludovicianus) populations. Although zinc phosphide poisoning of gallinaceous birds is not uncommon, there are few published accounts of nontarget chlorophacinone poisoning of wildlife. We report three mortality events involving nontarget rodenticide poisoning in several species, including wild turkeys (Meleagris gallopavo), a raccoon (Procyon lotor), and an American badger (Taxidea taxus). This includes the first documentation of chlorophacinone intoxication in wild turkeys and an American badger in the literature. The extent of nontarget poisoning in this area is currently unknown and warrants further investigation. PMID:21270011

  6. Geochemical characteristics of the Cenozoic basaltic rocks, Northwestern Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Saif, S. I.; Shah, S. M. A.

    1992-02-01

    In northwestern Saudi Arabia, an area of about 15 200 km is intermittently covered by basaltic rocks representing Cenozoic, intraplate continental volcanism. The present study is focused on the geochemical characteristics of these rocks, which are distinguished on the basis of field occurrences into three suites: 1. layered basalt (LB), 2. fragmented basalt (FB), and 3. cinder-cone material (CM), with varied ages. The rocks are olivine normative, belonging to the basanite-picrite-ankaramite series, with sodic and potassic varieties. A high degree of ferromagnesian fractionation and some compositional layering in the magma chamber are concluded. Crustal contamination indicated by some trace elements, progressively decreases with age, and hence, is interpreted as time dependent.

  7. Sinking velocity of particulate radiocesium in the northwestern North Pacific

    NASA Astrophysics Data System (ADS)

    Honda, Makio C.; Kawakami, Hajime

    2014-06-01

    Sinking particles (SP) were collected by time series sediment traps at two depths in the northwestern Pacific before and after the Fukushima Daiichi Nuclear Power Plant accident, and accident-derived particulate radiocesium was measured. Radiocesium (137Cs) was first detected at 500 m (4810 m) about 2 weeks (1 month) after the accident. 137Cs of SP collected over 1 year revealed that the time lag between two depths was larger than that for the first 137Cs detection (about 2 weeks). We estimated the transient sinking velocity (SV) from the cumulative temporal 137Cs flux and the time lags at the two depths. Although the SV of SP collected in very early period was large, the estimated SV of most particulate 137Cs (about 80%) was about 50 m d-1. Based on comparison of 137Cs concentration in total SP with that in SP without organic materials, we suspect that most of the 137Cs was likely incorporated into aluminosilicates.

  8. Intoxication of nontarget wildlife with rodenticides in northwestern Kansas.

    PubMed

    Ruder, Mark G; Poppenga, Robert H; Bryan, John A; Bain, Matt; Pitman, Jim; Keel, M Kevin

    2011-01-01

    The perception of prairie dogs (Cynomys spp.) both as a nuisance species and a keystone species presents a significant challenge to land, livestock, and wildlife managers. Anticoagulant and nonanticoagulant rodenticides are commonly employed to control prairie dog populations throughout their range. Chlorophacinone, and to a lesser extent zinc phosphide, are widely used in northwestern Kansas for controlling black-tailed prairie dog (Cynomys ludovicianus) populations. Although zinc phosphide poisoning of gallinaceous birds is not uncommon, there are few published accounts of nontarget chlorophacinone poisoning of wildlife. We report three mortality events involving nontarget rodenticide poisoning in several species, including wild turkeys (Meleagris gallopavo), a raccoon (Procyon lotor), and an American badger (Taxidea taxus). This includes the first documentation of chlorophacinone intoxication in wild turkeys and an American badger in the literature. The extent of nontarget poisoning in this area is currently unknown and warrants further investigation.

  9. Origin of arches in the northwestern Gulf of Mexico basin

    SciTech Connect

    Laubach, S.E.; Jackson, M.L.W. )

    1990-07-01

    The San Marcos and Sabine arches are prominent north- to northwest-trending basement uplifts in the northwestern Gulf of Mexico basin that may be late Mesozoic to Cenozoic foreland or intraplate folds rather than domes over plutons or buoyant basement blocks. These arches are subparallel to and contemporaneous with orogenic episodes in the northwest-trending fold-thrust belt of Mexico. Arch movement was also contemporaneous with rapid convergence between the North American and Pacific plates. Arch development in the gulf as a result of tectonic compression is plausible in view of increasing recognition of wide zones of foreland and intraplate deformation in continents. Current tectonic models of the development of the gulf inaccurately predict gradual, decelerating subsidence when these arches were most active.

  10. Floating debris in the Ligurian Sea, north-western Mediterranean.

    PubMed

    Aliani, Stefano; Griffa, Annalisa; Molcard, Anne

    2003-09-01

    Results from visual sightings of large floating debris are presented, taken in the Ligurian Sea, a sub-basin of the north-western Mediterranean Sea which belongs to the recently stated "Cetacean Sanctuary". Data have been collected during three oceanographic cruises, during the summer of 1997 and 2000. Results for the 1997 data suggest a debris density of the order of 15-25 objects km(-2), while for the 2000 data, a lower density of the order of 3-1.5 objects km(-2) is found. The difference between the two results appears statistically significant using simple tests. Possible reasons for the observed variability are discussed, including meteorological forcing, marine currents and debris input variability.

  11. Occurrence of Trichinella spp. in wild animals in northwestern Libya.

    PubMed

    Hosni, M M; Maghrbi, A A El; Ganghish, K S

    2013-01-01

    The present study determined the occurrence of Trichinella spp. in captured and some perished wildlife animals which included 70 hedgehogs, 19 red foxes, 13 common jackals and 8 crested porcupines in northwestern Libya. Muscle samples of these animals were examined by trichinoscopy. Trichinella larvae were detected only in 4 (5.7%) of the hedgehogs (Erinaceus algirus) and 2 (10.5%) of the red foxes (Vulpes vulpes). Larvae were found in the muscles of the diaphragm, abdomen, tongue, forelimb, hindlimb and intercostal muscles. Examination of tissue sections revealed the presence of numerous cysts within the muscle fibers containing one or more coiled or elongated larvae. Inflammatory cell infiltration was observed around the cysts especially at their poles. Results indicated the importance of wild animals as reservoirs of Trichinella larvae and their role in the transmission of the disease to other wild and domestic animals as well as humans. PMID:26623318

  12. Geophysical interpretations of the Libby thrust belt, northwestern Montana

    USGS Publications Warehouse

    Kleinkopf, M. Dean; with sections by Harrison, Jack Edward; Stanley, W.D.

    1997-01-01

    Interpretations of gravity and aeromagnetic anomaly data, supplemented by results from two seismic reflection profiles and five magnetotelluric soundings, were used to study buried structure and lithology of the Libby thrust belt of northwestern Montana. The gravity anomaly data show a marked correlation with major structures. The Purcell anticlinorium and the Sylvanite anticline are very likely cored by stacks of thrust slices of dense crystalline basement rocks that account for the large gravity highs across these two structures. Gravity anomaly data for the Cabinet Mountains Wilderness show a string of four broad highs. The principal magnetic anomaly sources are igneous intrusive rocks, major fault zones, and magnetite-bearing sedimentary rocks of the Ravalli Group. The most important magnetic anomalies in the principal study area are five distinct positive anomalies associated with Cretaceous or younger cupolas and stocks.

  13. Water resources of the White Earth Indian Reservation, northwestern Minnesota

    USGS Publications Warehouse

    Ruhl, J.F.

    1989-01-01

    Surface water also is a calcium magnesium bicarbonate type. Lake waters are hard and alkaline and are mesotrophic to eutrophic in productivity. Quality of the lake and stream water is suitable for native forms of freshwater biota, although the concentration of total recoverable mercury exceeds the 0.012 micrograms per liter maximum contaminant level; that level, established by USEPA for the organic form of dissolved mercury, is intended to protect against chronic effects on freshwater life. Available information, however, indicates that the amount of mercury in edible tissue from fish in alkaline lakes of northwestern Minnesota is within safe limits. The concentrations of phosphorus and nitrate in the streams are below levels that indicate pollution problems.

  14. Hantavirus Infection in Humans and Rodents, Northwestern Argentina

    PubMed Central

    Levis, Silvana; Calderón, Gladys; Ramirez, Josefina; Bravo, Daniel; Lozano, Elena; Ripoll, Carlos; St. Jeor, Stephen; Ksiazek, Thomas G.; Barquez, Ruben M.; Enria, Delia

    2003-01-01

    We initiated a study to elucidate the ecology and epidemiology of hantavirus infections in northern Argentina. The northwestern hantavirus pulmonary syndrome (HPS)–endemic area of Argentina comprises Salta and Jujuy Provinces. Between 1997 and 2000, 30 HPS cases were diagnosed in Jujuy Province (population 512,329). Most patients had a mild clinical course, and the death rate (13.3%) was low. We performed a serologic and epidemiologic survey in residents of the area, in conjunction with a serologic study in rodents. The prevalence of hantavirus antibodies in the general human population was 6.5%, one of the highest reported in the literature. No evidence of interhuman transmission was found, and the high prevalence of hantavirus antibody seemed to be associated with the high infestation of rodents detected in domestic and peridomestic habitats. PMID:14519242

  15. Occurrence of Trichinella spp. in wild animals in northwestern Libya

    PubMed Central

    Hosni, M.M.; Maghrbi, A.A. El; Ganghish, K.S.

    2013-01-01

    The present study determined the occurrence of Trichinella spp. in captured and some perished wildlife animals which included 70 hedgehogs, 19 red foxes, 13 common jackals and 8 crested porcupines in northwestern Libya. Muscle samples of these animals were examined by trichinoscopy. Trichinella larvae were detected only in 4 (5.7%) of the hedgehogs (Erinaceus algirus) and 2 (10.5%) of the red foxes (Vulpes vulpes). Larvae were found in the muscles of the diaphragm, abdomen, tongue, forelimb, hindlimb and intercostal muscles. Examination of tissue sections revealed the presence of numerous cysts within the muscle fibers containing one or more coiled or elongated larvae. Inflammatory cell infiltration was observed around the cysts especially at their poles. Results indicated the importance of wild animals as reservoirs of Trichinella larvae and their role in the transmission of the disease to other wild and domestic animals as well as humans. PMID:26623318

  16. Floods of January 15-17, 1974, in Northwestern Montana

    USGS Publications Warehouse

    Johnson, M.V.; Omang, R.J.

    1974-01-01

    Introduction Rain and snowmelt caused several streams in northwestern Montana to flood during January 15-17, 1974. The flooding was caused by a major rainstorm that extended from Montana through Idaho and Washington. The most damage occurred in the Kootenai River drainage, centering around the town of Libby. Also unusually high flows occurred on some streams in the Clark Fork basin. Throughout the area, ice jams contributed to much of the overbank flooding. Both the towns of Troy and Libby were partly flooded, but damage was greatest in and near Libby. Flood damage was estimated to be $4.9 million. No flood fatalities were listed. Most of the smaller streams equaled or exceeded a 50-year flood. A summary of flood stages and discharges for 24 sites in the Kootenai River drainage and 8 sites in the Clark Fork drainage is tabulated. A map shows the extent of flooding in the Libby area. (Woodard-USGS)

  17. Northwestern Pacific typhoon intensity controlled by changes in ocean temperatures.

    PubMed

    Mei, Wei; Xie, Shang-Ping; Primeau, François; McWilliams, James C; Pasquero, Claudia

    2015-05-01

    Dominant climatic factors controlling the lifetime peak intensity of typhoons are determined from six decades of Pacific typhoon data. We find that upper ocean temperatures in the low-latitude northwestern Pacific (LLNWP) and sea surface temperatures in the central equatorial Pacific control the seasonal average lifetime peak intensity by setting the rate and duration of typhoon intensification, respectively. An anomalously strong LLNWP upper ocean warming has favored increased intensification rates and led to unprecedentedly high average typhoon intensity during the recent global warming hiatus period, despite a reduction in intensification duration tied to the central equatorial Pacific surface cooling. Continued LLNWP upper ocean warming as predicted under a moderate [that is, Representative Concentration Pathway (RCP) 4.5] climate change scenario is expected to further increase the average typhoon intensity by an additional 14% by 2100. PMID:26601179

  18. Northwestern Pacific typhoon intensity controlled by changes in ocean temperatures.

    PubMed

    Mei, Wei; Xie, Shang-Ping; Primeau, François; McWilliams, James C; Pasquero, Claudia

    2015-05-01

    Dominant climatic factors controlling the lifetime peak intensity of typhoons are determined from six decades of Pacific typhoon data. We find that upper ocean temperatures in the low-latitude northwestern Pacific (LLNWP) and sea surface temperatures in the central equatorial Pacific control the seasonal average lifetime peak intensity by setting the rate and duration of typhoon intensification, respectively. An anomalously strong LLNWP upper ocean warming has favored increased intensification rates and led to unprecedentedly high average typhoon intensity during the recent global warming hiatus period, despite a reduction in intensification duration tied to the central equatorial Pacific surface cooling. Continued LLNWP upper ocean warming as predicted under a moderate [that is, Representative Concentration Pathway (RCP) 4.5] climate change scenario is expected to further increase the average typhoon intensity by an additional 14% by 2100.

  19. Demonstration of two pulses of Paleogene deformation in the Andes of Peru

    USGS Publications Warehouse

    Noble, D.C.; Sebrier, M.; Megard, F.; McKee, E.H.

    1985-01-01

    New radiometric ages of about 25 m.y. on volcanic materials in a marine intercalation within clastic continental strata of the Upper Moquegua Formation near Caraveli, southern Peru, together with an age of 25.3 ?? 0.4 m.y obtained by Tosdal et al. from a locality about 300 km to the ESE, show that the formation contains strata of late Oligocene as well as Miocene age, and demonstrate that the coastal region was at a low elevation during latest Oligocene time. Because the unconformities between the Upper Moquegua Formation and the underlying Lower Moquegua Formation, and between the Lower Moquegua Formation and underlying Paleocene rocks cannot both represent the same tectonic event, two discrete Paleogene events must be present in the Andes of Peru. Although the exact timing of these events is uncertain, the unconformities are likely to be of Paleocene and middle Eocene age or possibly of middle Eocene and Oligocene age. ?? 1985.

  20. Three new species of Oxysarcodexia Townsend (Diptera: Sarcophagidae)
    from the Colombian Andes.

    PubMed

    Souza, Carina Mara De; Buenaventura, Eliana

    2016-01-01

    Three new species of Oxysarcodexia Townsend (Diptera: Sarcophagidae) from the Colombian Andes are described based on male specimens collected using decaying animal matter as bait: Oxysarcodexia catica sp. n., O. laclaricola sp. n., and O. liliarum sp. n. The straight and narrow cercal prong with an acute apex, and the juxta enlarged distally and folded backwards of O. catica sp. n. resemble these structures in O. fraterna Lopes, O. peruviana (Lopes) and O. vittata (Walker). The shape of the cercus of O. laclaricola sp. n. is similar to that of O. floricola Lopes, whereas its vesica is similar in shape to that of O. cyaniforceps (Hall). Oxysarcodexia liliarum sp. n. resembles O. favorabilis (Lopes) in the inflorescence-like phallus and enlarged juxta. The postero-distal phallic enlargement of O. catica sp. n. and O. liliarum sp. n. support the inclusion of these species in the so-called "Xarcophaga group" (sensu Lopes). PMID:27394253

  1. The Major Cellular Sterol Regulatory Pathway Is Required for Andes Virus Infection

    PubMed Central

    Riblett, Amber M.; Didigu, Chukwuka A.; Wilen, Craig B.; Malani, Nirav; Male, Frances; Lee, Fang-Hua; Bushman, Frederic D.; Cherry, Sara; Doms, Robert W.; Bates, Paul; Briley, Kenneth

    2014-01-01

    The Bunyaviridae comprise a large family of RNA viruses with worldwide distribution and includes the pathogenic New World hantavirus, Andes virus (ANDV). Host factors needed for hantavirus entry remain largely enigmatic and therapeutics are unavailable. To identify cellular requirements for ANDV infection, we performed two parallel genetic screens. Analysis of a large library of insertionally mutagenized human haploid cells and a siRNA genomic screen converged on components (SREBP-2, SCAP, S1P and S2P) of the sterol regulatory pathway as critically important for infection by ANDV. The significance of this pathway was confirmed using functionally deficient cells, TALEN-mediated gene disruption, RNA interference and pharmacologic inhibition. Disruption of sterol regulatory complex function impaired ANDV internalization without affecting virus binding. Pharmacologic manipulation of cholesterol levels demonstrated that ANDV entry is sensitive to changes in cellular cholesterol and raises the possibility that clinically approved regulators of sterol synthesis may prove useful for combating ANDV infection. PMID:24516383

  2. Paleoseismicity and neotectonics of the Cordillera Blanca fault zone, Northern Peruvian Andes.

    USGS Publications Warehouse

    Schwartz, D.P.

    1988-01-01

    The Cordillera Blanca fault zone is a major W dipping normal fault that bounds the W side of a 120- 170-km wide zone of active extension along the crest of the N Peruvian Andes. The fault is approximately 210 km long and exhibits continuous geomorphic evidence of repeated late Pleistocene and Holocene displacements but has not been the source of historical or teleseismically recorded earthquakes. Trenching and mapping of fault scarps provide new information on earthquake recurrence, slip rate, timing of the most recent events and Andean neotectonics. At Quebrada Queroccocha, 55 km from valley fill lacustrine and fluvial deposits are displaced 7.5-8 m. Scarp profiles, tectonic terraces, and trench exposures indicate 5 to 7 scarp-forming earthquakes of 2-3 m per event during the past 11 000-14 000 yrs at this location.-from Author

  3. Mapping advanced argillic alteration zones with ASTER and Hyperion data in the Andes Mountains of Peru

    NASA Astrophysics Data System (ADS)

    Ramos, Yuddy; Goïta, Kalifa; Péloquin, Stéphane

    2016-04-01

    This study evaluates Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Hyperion hyperspectral sensor datasets to detect advanced argillic minerals. The spectral signatures of some alteration clay minerals, such as dickite and alunite, have similar absorption features; thus separating them using multispectral satellite images is a complex challenge. However, Hyperion with its fine spectral bands has potential for good separability of features. The Spectral Angle Mapper algorithm was used in this study to map three advanced argillic alteration minerals (alunite, kaolinite, and dickite) in a known alteration zone in the Peruvian Andes. The results from ASTER and Hyperion were analyzed, compared, and validated using a Portable Infrared Mineral Analyzer field spectrometer. The alterations corresponding to kaolinite and alunite were detected with both ASTER and Hyperion (80% to 84% accuracy). However, the dickite mineral was identified only with Hyperion (82% accuracy).

  4. Contrasting response of glacierized catchments in the Central Himalaya and the Central Andes to climate change

    NASA Astrophysics Data System (ADS)

    Ragettli, Silvan; Pellicciotti, Francesca; Immerzeel, Walter

    2015-04-01

    The Andes of South America and the Himalaya in high-mountain Asia are two regions where advanced simulation models are of vital importance to anticipate the impacts of climate change on water resources. The two mountain systems hold the largest ice masses outside the polar regions. Major rivers originate here and downstream regions are densely populated. In the long run, glacier recession generates concerns about the sustainability of summer runoff. This study benefits from recent efforts of carefully planned short-term field experiments in two headwater catchments in the Central Andes of Chile and in the Central Himalaya in Nepal. The two study catchments contrast in terms of their climate and in the characteristics of their glaciers. A systematic approach is developed, built upon the available local data, to reduce the predictive uncertainty of a state-of-the-art glacio-hydrological model used for the projection of 21st century glacier changes and catchment runoff. The in-situ data are used for model development and step-wise, multivariate parameter calibration. Catchment runoff and remotely sensed MODIS and Landsat snow cover are used for model validation. The glacio-hydrological model simulates the water cycle with a high temporal (hourly time steps) and spatial (100 m grid cells) resolution and accounts for processes typical of both regions like glacier melt under debris cover or mass redistribution through avalanching. Future projections are based on the outputs of twelve stochastically downscaled global climate models for two emission scenarios (RCP 4.5 and RCP 8.5). This is one of the first truly intercomparative modeling studies at the catchment scale across mountain regions of the world to assess and compare future changes in glaciers and snow cover and associated impacts on streamflow production. Both catchments will experience significant glacier mass loss throughout the twenty-first century. However, the trajectories of simulated future runoff and

  5. Novel Strain of Andes Virus Associated with Fatal Human Infection, Central Bolivia

    PubMed Central

    Cruz, Cristhopher D.; Vallejo, Efrain; Agudo, Roberto; Vargas, Jorge; Blazes, David L.; Guevara, Carolina; Laguna-Torres, V. Alberto; Halsey, Eric S.; Kochel, Tadeusz J.

    2012-01-01

    To better describe the genetic diversity of hantaviruses associated with human illness in South America, we screened blood samples from febrile patients in Chapare Province in central Bolivia during 2008–2009 for recent hantavirus infection. Hantavirus RNA was detected in 3 patients, including 1 who died. Partial RNA sequences of small and medium segments from the 3 patients were most closely related to Andes virus lineages but distinct (<90% nt identity) from reported strains. A survey for IgG against hantaviruses among residents of Chapare Province indicated that 12.2% of the population had past exposure to >1 hantaviruses; the highest prevalence was among agricultural workers. Because of the high level of human exposure to hantavirus strains and the severity of resulting disease, additional studies are warranted to determine the reservoirs, ecologic range, and public health effect of this novel strain of hantavirus. PMID:22515983

  6. Landsat Thematic Mapper observations of debris avalanche deposits in the Central Andes

    NASA Technical Reports Server (NTRS)

    Francis, P. W.; Wells, G. L.

    1988-01-01

    Remote sensing with the Landsat Thematic Mapper of debris avalanche deposits in the Central Andes between 18 and 27 deg S revealed, for the first time, the presence of 28 breached volcanic cones and 11 major volcanic debris avalanche deposits, several of which cover areas in excess of 100 sq km. It is concluded that such avalanche deposits are normal products of the evolution of large composite volcanoes, comparable with lava and pyroclastic flow deposits. A statistical survey of 578 composite volcanoes in the same area indicated that a majority of cones which achieve edifice heights between 2000 and 3000 m may undergo sector collapse. The paper describes morphological criteria for identifying breached composite cones and volcanic debris avalanches using orbital images.

  7. Controls on continental strain partitioning above an oblique subduction zone, Northern Andes

    NASA Astrophysics Data System (ADS)

    Schütt, Jorina M.; Whipp, David M., Jr.

    2016-04-01

    Strain partitioning is a common process at obliquely convergent plate margins dividing oblique convergence into margin-normal slip on the plate-bounding fault and horizontal shearing on a strike-slip system parallel to the subduction margin. In subduction zones, strain partitioning in the upper continental plate is mainly controlled by the shear forces acting on the plate interface and the strength of the continental crust. The plate interface forces are influenced by the subducting plate dip angle and the obliquity angle between the normal to the plate margin and the convergence velocity vector, and the crustal strength of the continent is strongly affected by the presence or absence of a volcanic arc, with the presence of the volcanic arcs being common at steep subduction zones. Along the ˜7000 km western margin of South America the convergence obliquity, subduction dip angles and presence of a volcanic arc all vary, but strain partitioning is only observed along parts of it. This raises the questions, to what extent do subduction zone characteristics control strain partitioning in the overriding continental plate, and which factors have the largest influence? We address these questions using lithospheric-scale 3D numerical geodynamic experiments to investigate the influence of subduction dip angle, convergence obliquity, and weaknesses in the crust owing to the volcanic arc on strain partitioning behavior. We base the model design on the Northern Volcanic Zone of the Andes (5° N - 2° S), characterized by steep subduction (˜ 35°), a convergence obliquity between 31° -45° and extensive arc volcanism, and where strain partitioning is observed. The numerical modelling software (DOUAR) solves the Stokes flow and heat transfer equations for a viscous-plastic creeping flow to calculate velocity fields, thermal evolution, rock uplift and strain rates in a 1600 km x 1600 km box with depth 160 km. Subduction geometry and material properties are based on a

  8. Geologic evolution of the Cordillera Darwin orogenic core complex, Southern Andes

    NASA Astrophysics Data System (ADS)

    Nelson, E. P.

    1981-08-01

    Located in the east-west trending Andes of Tierra del Fuego is a structural culmination exposing deeper crustal levels than in surrounding areas, termed an orogenic core complex because of the localization there of relatively high-grade metamorphism, intense polyphase deformation, and differential uplift. Strongly deformed and regionally metamorphosed pre-Late Jurassic basement rocks mainly of sedimentary origin are unconformably overlain by a cover sequence of Upper Jurassic silicic-intermediate volcanic rocks (Tobifera Formation) and Lower Cretaceous clastic sedimentary rocks (Yahgan Formation). The D1 and D2 phases produced major and minor fold structures, extension and intersection lineations, and axial planar and transposition foliations in complex patterns similar to those in other collision-type orogens. The Darwin and Beagle suites show affinities with S- and I-type granitic suites respectively.

  9. Multiethnicity, pluralism, and migration in the south central Andes: An alternate path to state expansion

    PubMed Central

    Goldstein, Paul S.

    2015-01-01

    The south central Andes is known as a region of enduring multiethnic diversity, yet it is also the cradle of one the South America’s first successful expansive-state societies. Social structures that encouraged the maintenance of separate identities among coexistent ethnic groups may explain this apparent contradiction. Although the early expansion of the Tiwanaku state (A.D. 600–1000) is often interpreted according to a centralized model derived from Old World precedents, recent archaeological research suggests a reappraisal of the socio-political organization of Tiwanaku civilization, both for the diversity of social entities within its core region and for the multiple agencies behind its wider program of agropastoral colonization. Tiwanaku’s sociopolitical pluralism in both its homeland and colonies tempers some of archaeology’s global assumptions about the predominant role of centralized institutions in archaic states. PMID:26195732

  10. Southern rim of Pacific Ocean basin: southern Andes to southern Alps

    SciTech Connect

    Dalziel, I.W.D.; Garrett, S.W.; Grunow, A.M.; Pankhurst, R.J.; Storey, B.C.; Vennum, W.R.

    1986-07-01

    Between the southern Andes of Tierra del Fuego and the southern Alps of New Zealand lies the least accessible and geologically least explored part of the Pacific Ocean basin. A joint United Kingdom-United States project was initiated in 1983 to elucidate the geologic history and structure of the Pacific margin of Antarctica from the Antarctic Peninsula to Pine Island Bay at approximately lone. 105/sup 0/W. The first season (1983-1984) of this West Antarctic Tectonics Project was spent in the Ellsworth-Whitmore crustal block, and the second (1984-1985) in the Thurston Island crustal block. The project involves structural and general field geology, petrology, geochemistry, paleomagnetism, and airborne geophysics (magnetics and radar ice echo sounding). A final geologic season will be spent in the Pensacola Mountains of the Transantarctic Range in 1987-1988.

  11. Understanding the Rainfall Daily Climatology of Northwestern Mexico

    NASA Astrophysics Data System (ADS)

    Brito-Castillo, L.

    2007-05-01

    Maximum monthly precipitation (MMP) over northwestern Mexico is not concurrent because it occurs in different months from July through September. However, instead of occurring progressively from one month to the next as latitude increases, as it might be logic since rains move progressively from south to north as monsoon develops, MMP occurs in July in latitudes of Jalisco state, then MMP shifts to August more to the north in latitudes of Nayarit state and along the eastern coast of the Gulf of California, then it occurs in July in higher latitudes through the main axis of the Sierra Madre Occidental (SMO), and finally MMP shifts to September to the west in the California Peninsula. The maximum monthly streamflow occurs in a similar pattern as MMP does but one month later. When daily rainfall climatology of the region is calculated, i.e. the long-term mean per day from stations with more than 20 years of data between 1940 and 2004, it is possible to understand why the behavior of MMP occurs in a July-August-July pattern from south to north. Preliminary results indicate that at latitudes of Nayarit state normal frequent storms with abundant rains develop at the end of July and through the August. These rains sum to the rains that move from the south to the north, as monsoon develops increasing the volume of precipitations at those latitudes in August. To the east crossing the SMO through northwestern Zacatecas state maximum volume of precipitations also is observed in August. However, in higher latitudes it is not observed any increment of rains in August and consequently maximum volume of precipitations occurs in July. To understand the dynamics of the rains at the latitudes of Nayarit state it results necessary to investigate the source of these local rains and explain why the increase of precipitations in August is limited at those latitudes.

  12. The Northwestern (Maghreb) boundary of the Nubia (Africa) Plate

    NASA Astrophysics Data System (ADS)

    Mauffret, Alain

    2007-01-01

    A study of the present compressional deformation of the Northwestern (Maghreb) Nubia (Africa) margin is derived from the analysis of more than 20,000 km of seismic profiles. In the western part the compression is distributed in a large zone with on-land compression in Algeria, mainly strike-slip deformation on the Algerian margin and folds and strike-slip faulting in Eastern Spain. In the middle of the Algerian margin, around Algiers, the evidences of compression become more obvious. In this area a ridge trending N-S that is interpreted as a middle to late Miocene spreading center interacted with the transpressional margin that trends E-W. North of the location of the Boumerdes-Zemmouri earthquake the oceanic crust is deformed by blind thrusts up to 60 km from the coast. These thrusts are south dipping and with the northward dipping thrusts located onshore form a wedge that maybe a positive flower structure at a crustal scale related to the right-lateral transpression of the margin. In the eastern part of the Northwestern (Maghreb) Nubia (Africa) Deformed Belt, off eastern Algeria and Tunisia, the deformation is more intense but limited to the north by the continental slope. Large late Miocene Tortonian folds are cut by the Messinian erosional surface but the present deformation is also evident. It is suggested that the deformation with a double vergence may be followed up to the north of Sicily. After the docking (18 Ma) of the Kabylies to the Africa Plate, the crust has been thinned and the Algerian Basin opened during the middle-late Miocene with an E-W direction. From the late Miocene to the Present the margin has been rethickened by transpression and uplifted.

  13. Modeling Soil Organic Carbon Variation Along Climatic and Topographic Trajectories in the Central Andes

    NASA Astrophysics Data System (ADS)

    Gavilan, C.; Grunwald, S.; Quiroz, R.; Zhu, L.

    2015-12-01

    The Andes represent the largest and highest mountain range in the tropics. Geological and climatic differentiation favored landscape and soil diversity, resulting in ecosystems adapted to very different climatic patterns. Although several studies support the fact that the Andes are a vast sink of soil organic carbon (SOC) only few have quantified this variable in situ. Estimating the spatial distribution of SOC stocks in data-poor and/or poorly accessible areas, like the Andean region, is challenging due to the lack of recent soil data at high spatial resolution and the wide range of coexistent ecosystems. Thus, the sampling strategy is vital in order to ensure the whole range of environmental covariates (EC) controlling SOC dynamics is represented. This approach allows grasping the variability of the area, which leads to more efficient statistical estimates and improves the modeling process. The objectives of this study were to i) characterize and model the spatial distribution of SOC stocks in the Central Andean region using soil-landscape modeling techniques, and to ii) validate and evaluate the model for predicting SOC content in the area. For that purpose, three representative study areas were identified and a suite of variables including elevation, mean annual temperature, annual precipitation and Normalized Difference Vegetation Index (NDVI), among others, was selected as EC. A stratified random sampling (namely conditioned Latin Hypercube) was implemented and a total of 400 sampling locations were identified. At all sites, four composite topsoil samples (0-30 cm) were collected within a 2 m radius. SOC content was measured using dry combustion and SOC stocks were estimated using bulk density measurements. Regression Kriging was used to map the spatial variation of SOC stocks. The accuracy, fit and bias of SOC models was assessed using a rigorous validation assessment. This study produced the first comprehensive, geospatial SOC stock assessment in this

  14. Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

    PubMed

    Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

    2014-06-01

    Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build

  15. Vitamin D Status among Older Adults Residing in the Littoral and Andes Mountains in Ecuador

    PubMed Central

    Orces, Carlos H.

    2015-01-01

    Objectives. To estimate the prevalence of 25-hydroxyvitamin D (25(OH)D) deficiency and its determinants among older adults in Ecuador. Methods. 25(OH)D deficiency and insufficiency prevalence rates were examined among participants in the National Survey of Health, Wellbeing, and Aging. Logistic regression models were used to evaluate demographic characteristics associated with 25(OH)D deficiency. Results. Of 2,374 participants with a mean age of 71.0 (8.3) years, 25(OH)D insufficiency and deficiency were present in 67.8% (95% CI, 65.3–70.2) and 21.6% (95% CI, 19.5–23.7) of older adults in Ecuador, respectively. Women (OR, 3.19; 95% CI, 3.15–3.22), self-reported race as Indigenous (OR, 2.75; 95% CI, 2.70–2.80), and residents in rural (OR, 4.49; 95% CI, 4.40–4.58) and urban (OR, 2.74; 95% CI, 2.69–2.80) areas of the Andes Mountains region were variables significantly associated with 25(OH)D deficiency among older adults. Conclusions. Despite abundant sunlight throughout the year in Ecuador, 25(OH)D deficiency was significantly prevalent among older women, Indigenous subjects, and subjects residing in the Andes Mountains region of the country. The present findings may assist public health authorities to implement policies of vitamin D supplementation among older adults at risk for this condition. PMID:26301259

  16. Proliferation of Hydroelectric Dams in the Andean Amazon and Implications for Andes-Amazon Connectivity

    PubMed Central

    Finer, Matt; Jenkins, Clinton N.

    2012-01-01

    Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1) There is a critical need for further strategic regional and basin scale evaluation of dams. 2) There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3) Reconsideration of hydropower as a low-impact energy source in the Neotropics. PMID:22529979

  17. Energy Balance of High Altitude Glaciarised Basins In The Central Andes: Climatic and Hydrological Aspects

    NASA Astrophysics Data System (ADS)

    Corripio, J.; Purves, R.

    The Central Andes of Chile and Argentina can be classified as climatic deserts, yet they support very large populations and a rich agriculture, thanks to melt water from snow melt and glaciers. Meteorological data from one automatic weather station in- stalled on two different glaciers at 3300m and 4600m a.s.l. in the Chilean Andes (700 W, 330 S), are presented and discussed. The relative importance of the terms in the en- ergy balance equation shows substantial differences from that of mid-latitude Alpine glaciers, with turbulent heat transfer accounting for 10 to 20% of the net energy bal- ance. Extremely low relative humidity (up to 8%) and moderate winds result in high evaporation rates. Intense evaporation, together with effective radiative cooling, dew point well below freezing and intense solar radiation favour differential ablation of the snow surface, which results in the formation of snow penitentes, these unique forms result in a further modification of the energy balance. The intense solar radia- tion enhances the effect of the surrounding topography on snow-covered areas, which is modelled using terrain algorithms for digital elevation models. Stable conditions and a clear atmosphere permit effective use of solar radiative models with good re- sults. Remoteness and lack of infrastructures complicate access, which was made us- ing traditional transportation methods in the region: mules! Lack of data and limited budget was partially overcome by developing an alternative simple and economical remote sensing tool for snow cover monitoring and albedo estimation using terrestrial photography. Finally, the output of a distributed snow melt model is compared to dis- charge data from a glacier whose outflow is monitored by the Chilean Water Board, as it is the main source of drinking water for Santiago de Chile.

  18. Carbonatite diversity in the Central Andes: the Ayopaya alkaline province, Bolivia

    NASA Astrophysics Data System (ADS)

    Schultz, Frank; Lehmann, Bernd; Tawackoli, Sohrab; Rössling, Reinhard; Belyatsky, Boris; Dulski, Peter

    2004-12-01

    The Ayopaya province in the eastern Andes of Bolivia, 100 km NW of Cochabamba, hosts a Cretaceous alkaline rock series within a Palaeozoic sedimentary sequence. The alkaline rock association comprises nepheline-syenitic/foyaitic to ijolitic intrusions, carbonatite, kimberlite, melilititic, nephelinitic to basanitic dykes and diatremes, and a variety of alkaline dykes. The carbonatites display a wide petrographic and geochemical spectrum. The Cerro Sapo area hosts a small calciocarbonatite intrusion and a multitude of ferrocarbonatitic dykes and lenses in association with a nepheline-syenitic stock. The stock is crosscut by a spectacular REE-Sr-Th-rich sodalite-ankerite-baryte dyke system. The nearby Chiaracke complex represents a magnesiocarbonatite intrusion with no evidence for a relationship to igneous silicate rocks. The magnesiocarbonatite (Σ REE up to 1.3 wt%) shows strong HREE depletion, i.e. unusually high La/Yb ratios (520 1,500). Calciocarbonatites (Σ REE up to 0.5 wt%) have a flatter REE distribution pattern (La/Yb 95 160) and higher Nb and Zr contents. The sodalite-ankerite-baryte dyke system shows geochemical enrichment features, particularly in Na, Ba, Cl, Sr, REE, which are similar to the unusual natrocarbonatitic lavas of the recent volcano of Oldoinyo Lengai, Tanzania. The Cerro Sapo complex may be regarded as an intrusive equivalent of natrocarbonatitic volcanism, and provides an example for carbonatite genesis by late-stage crystal fractionation and liquid immiscibility. The magnesiocarbonatite intrusion of Chiaracke, on the other hand, appears to result from a primary carbonatitic mantle melt. Deep seated mantle magmatism/metasomatism is also expressed by the occurrence of a kimberlite dyke. Neodymium and strontium isotope data (ɛNd 1.4 5.4, 87Sr/86 Sr

  19. High-resolution satellite-gauge merged precipitation climatologies of the Tropical Andes

    NASA Astrophysics Data System (ADS)

    Manz, Bastian; Buytaert, Wouter; Zulkafli, Zed; Lavado, Waldo; Willems, Bram; Robles, Luis Alberto; Rodríguez-Sánchez, Juan-Pablo

    2016-02-01

    Satellite precipitation products are becoming increasingly useful to complement rain gauge networks in regions where these are too sparse to capture spatial precipitation patterns, such as in the Tropical Andes. The Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (TPR) was active for 17 years (1998-2014) and has generated one of the longest single-sensor, high-resolution, and high-accuracy rainfall records. In this study, high-resolution (5 km) gridded mean monthly climatological precipitation is derived from the raw orbital TPR data (TRMM 2A25) and merged with 723 rain gauges using multiple satellite-gauge (S-G) merging approaches. The resulting precipitation products are evaluated by cross validation and catchment water balances (runoff ratios) for 50 catchments across the Tropical Andes. Results show that the TPR captures major synoptic and seasonal precipitation patterns and also accurately defines orographic gradients but underestimates absolute monthly rainfall rates. The S-G merged products presented in this study constitute an improved source of climatological rainfall data, outperforming the gridded TPR product as well as a rain gauge-only product based on ordinary Kriging. Among the S-G merging methods, performance of inverse distance interpolation of satellite-gauge residuals was similar to that of geostatistical methods, which were more sensitive to gauge network density. High uncertainty and low performance of the merged precipitation products predominantly affected regions with low and intermittent precipitation regimes (e.g., Peruvian Pacific coast) and is likely linked to the low TPR sampling frequency. All S-G merged products presented in this study are available in the public domain.

  20. Gene expression in the Andes; relevance to neurology at sea level.

    PubMed

    Appenzeller, Otto; Minko, Tamara; Pozharov, Vitaly; Bonfichi, Maurizio; Malcovati, Luca; Gamboa, Jorge; Bernardi, Luciano

    2003-03-15

    Chronic mountain sickness (CMS), a maladaptation syndrome to chronic hypoxia, occurs in the Andes. Gene expression differences in Andeans could explain adaptation and maladaptation to hypoxia, both of which are relevant to neurology at sea level. Expression of genes responsive to cellular oxygen concentration, hypoxia-inducible factor-1alpha (HIF-1alpha), three splicing variants of vascular endothelial growth factor (VEGF) and von Hippel-Lindau protein (pVHL) was measured by reverse transcription polymerase chain reaction (RT-PCR) in 12 Cerro de Pasco (CP) (altitude 4338 m) natives and 15 CMS patients in CP. Thirteen high altitude natives living in Lima and five Lima natives were sea level controls. A CMS score (CMS-sc) was assigned clinically. Expression was related to the clinical assessment. High expression of HIF-1alpha and VEGF-121 was found in CMS (P<0.001). Samples from CP had higher expression than those from Lima (P<0.001). Expression of HIF-1alpha and VEGF-121 was related to age (P<0.001); adjusting for age did not abolish the group effect. Higher CMS-sc was related to expression independent of age (P<0.001). VEGF-165 and -189 were expressed only in CMS. Birth altitude had no effect on gene expression. pVHL was not quantifiable.HIF-1alpha and VEGF-121 participate in adaptation to hypoxia. The high levels may explain blood vessel proliferation in Andeans and hold lessons for patients at sea level. VEGF-165 expression suggests that it contributes to preservation of neuronal function in human chronic hypoxia. VHL mutations may mark those destined to develop neural crest tumors which are common in the Andes.