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Sample records for northwestern venezuelan andes

  1. Seismic evidence for blind thrusting of the northwestern flank of the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    de Toni, Bruno; Kellogg, James

    1993-12-01

    Surface geology and seismic and well data from the northwestern flank of the Venezuelan Andes indicate overthrusting of Andean basement rocks toward the adjacent Maracaibo Basin along a blind thrust fault. The frontal monocline is interpreted as the forelimb of a northwestward verging fault-related fold deformed over a crustal-scale ramp. The Andean block has been thrust 20 km to the northwest and uplifted 10 km on a ramp that dips about 20°-30° southeastward. The thrust fault ramps up through crystalline basement rocks to a decollement horizon within the shaly units of the Cretaceous Colon-Mito Juan formations. Backthrusts in the monocline produce a wedge geometry and reduce the amount of blind slip required on the decollement northwest of the Andes. The rigid Andean uplift was caused by northwest-southeast compressive tectonic forces related to the convergence of the Caribbean plate, the Panama volcanic arc, and northwestern South America. The thick (up to 6 km) molasse deposits accumulated in the foredeep basin indicate that the Venezuelan Andes started to rise as early as the early Miocene. However, a late Miocene intramolasse unconformity marks the beginning of the formation of the monocline and the greatest uplift. The crustal-scale fault-related fold model may explain structural features seen in other areas of basement-involved foreland deformation.

  2. Morphostructural Analysis of an Escape Tectonic Zone : the North-Western Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Dhont, D.; Backe, G.; Hervouet, Y.; Niviere, B.

    2004-12-01

    Lateral motions in active collisional areas have been mainly described in the Asian and European belts. The most common view is that part of the intracontinental convergence between to plates is accommodated by major strike-slip faults bounding a lithospheric block that laterally moves away. This process, privileging horizontal compressional forces at boundaries of the moving block corresponds to an extrusion or escape of the continental landmass. Diffuse extensional deformation within the block implies that buoyancy forces, leading eventually to an extensional collapse, must be taken into account. Escape of the block is perpendicular to the convergence direction of the orogen and can only occur if a free lateral boundary exists. Our study concerns the analysis of the deformation in the northwestern part of the Venezuelan Andes, located in the northern part of South America. It is based on analysis of satellite and Digital Elevation Model imagery, complemented by field structural observations. We shall describe new tectonic features advocating that part of the belt is subjected to lateral escape tectonics during the Plio-Quaternary. The zone displays major active faults forming crustal blocks having a triangular shape pattern, and which are moving toward the north-east. The triangular corners are composed of smaller pluri-kilometre size crustal blocks bounded by normal faults. A major result is that in an area characterized by on-going intracontinental convergence, extension and strike-slip deformations predominate. In order to better constrain the depth of the deformation, we have generated a 3-D geologic model displaying the seismicity the area showing that the earthquakes are mainly restricted to the crust. The type and distribution of the deformation are not consitent with the behaviour of a simple rigid extrusion. The Venezuelan Andes are rather composed of crustal blocks that are tilted and move relative to each others. This is consistent with extensional

  3. Evidence from the northwestern Venezuelan Andes for extraterrestrial impact: The black mat enigma

    NASA Astrophysics Data System (ADS)

    Mahaney, W. C.; Kalm, V.; Krinsley, D. H.; Tricart, P.; Schwartz, S.; Dohm, J.; Kim, K. J.; Kapran, B.; Milner, M. W.; Beukens, R.; Boccia, S.; Hancock, R. G. V.; Hart, K. M.; Kelleher, B.

    2010-03-01

    A carbon-rich black layer encrusted on a sandy pebbly bed of outwash in the northern Venezuelan Andes, previously considered the result of an alpine grass fire, is now recognized as a 'black mat' candidate correlative with Clovis Age sites in North America, falling within the range of 'black mat' dated sites (~ 12.9 ka cal BP). As such, the bed at site MUM7B, which dates to < 11.8 ka 14C years BP (raw dates) and appears to be contemporaneous with the Younger Dryas (YD) cooling event, marks a possibly much more extensive occurrence than previously identified. No fossils (megafauna) or tool assemblages were observed at this newly identified candidate site (3800 a.m.s.l.), as in the case of the North American sites. Here, evidence is presented for an extraterrestrial impact event at ~ 12.9 ka. The impact-related Andean bed, located ~ 20 cm above 13.7-13.3 ka cal BP alluvial and glaciolacustrine deposits, falls within the sediment characteristics and age range of 'black mat' dated sites (~ 12.9 ka cal BP) in North America. Site sediment characteristics include: carbon, glassy spherules, magnetic microspherules, carbon mat 'welded' onto coarse granular material, occasional presence of platinum group metals (Rh and Ru), planar deformation features (pdfs) in fine silt-size fragmental grains of quartz, as well as orthoclase, and monazite (with an abundance of Rare Earth Elements—REEs). If the candidate site is 'black mat', correlative with the 'black mat' sites of North America, such an extensive occurrence may support the hypothesized airburst/impact over the Laurentide Glacier, which led to a reversal of Allerød warming and the onset of YD cooling and readvance of glaciers. While this finding does not confirm such, it merits further investigation, which includes the reconnaissance for additional sites in South America. Furthermore, if confirmed, such an extensive occurrence may corroborate an impact origin.

  4. Orogenic float of the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Monod, Bernard; Dhont, Damien; Hervouët, Yves

    2010-07-01

    The Venezuelan (or Mérida) Andes are a NE-trending intracontinental orogen that started to rise from the Middle Miocene due to the E-W far field convergence between the Maracaibo block to the northwest and the Guyana shield to the southeast. Oblique convergence is responsible for strain partitioning with thrusting along both foreland basins and right-lateral strike-slip faulting along the NE-SW Boconó fault cutting the Venezuelan Andes along-strike. The central part of the belt is also cut by the N-S left-lateral strike-slip Valera fault that connects the Boconó fault, both faults bounding the Trujillo block that escapes towards the NNE. Even though the regional geology of belt is well known, its structure at depth remains a matter of debate. Our work, based on the integration of geological and geophysical data aims to better constrain the deep geometry of faults and the tectonic evolution of the mountain belt. We used the orogenic float model to construct two NW-SE trans-Andean crustal scale balanced sections. The Late Neogene-Quaternary shortening varies from 40 km in the south to 30 km in the north across the Trujillo block, indicating that a quarter of the deformation seems to be absorbed by the tectonic escape process. More importantly, a major reorganization in the crust took place in the Early Pliocene. It is characterized by the imbrication of the Maracaibo crust into the Guyana crust. This resulted in the subduction of the Guyana lower crust and the formation of a NW-vergent basement thrust propagating upwards and surfacing along the Las Virtudes thrust. Rapid uplift of the northern flank of the belt subsequently occurred together with massive deposition of the Plio-Quaternary coarse grained Betijoque formation in the northwestern foreland basin.

  5. 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.

  6. 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.

  7. Tectonics of the northern Venezuelan Andes from satellite images analysis

    NASA Astrophysics Data System (ADS)

    Dhont, D.; Backé, G.; Hervouët, Y.

    2003-04-01

    The northern part of the Venezuelan (or Merida) Andes is a complex area comprising a Cretaceous to Quaternary sedimentary sequence that recorded two main stages of deformation: (1) the uplifting of the Carribean belt in the Cretaceous-Eocene (Carribean stage), which is superimposed by (2) the building of the Venezuelan Andes since the Miocene (Andean stage). The study area is located at the junction between the Merida Andes and the Caribbean belt, and constitutes a key zone to understand the transition between these two orogens. Our aim is to implement the structural mapping in order to propose a new model of deformation at regional scale. The methodology is based on analysis of Landsat TM, SPOT, radarsat and DEM images, and is complemented by geological studies in the field. Integration of this complementary data set into a GIS enables a new understanding of the tectonics of the northern Venezuelan Andes during the Neogene-Quaternary. We focused on three main areas where the structures are clearly exposed. In the Mene Grande area, our structural analysis allows to precise the geometry and timing of deformations. The Cerro la Galera anticline is a fault bend fold propagating to the SW that developped along the Burro Negro fault during the Eocene-Oligocene and then eroded. The Cerro La Luna (or Cerro Misoa) is a pop-up structure that developped later during the Andean stage. In the Jirajara area, we have evidenced a releasing-bend basin at left-stepping offset of the Valera fault. To the east, this basin is surrounded by the relief of the Serrania de Jirajara which gravitationally collapses towards the lowland of the basin. In the Sierra de Barragua area, we mapped the left-lateral strike-slip Rio Diquiva fault 25 km east of the Valera fault. This fault is a major structure bounding two distincts areas of sedimentation during the Eocene. The synthesis of these observations shows that the northern Venezuelan Andes consist in a mosaic of independent crustal blocks

  8. [Description of the seismological network of the Venezuelan Andes].

    PubMed

    Guada, Carlos; Morandi, María; Silva, José

    2003-01-01

    Western Venezuela shows a broad zone characterized by a moderate seismicity level, which has been the scenery of various historic earthquakes of destructive character. The beginning of the seismic instrumentation in the area dates from 1969, nevertheless it was 10 years later when the seismological network of the Venezuelan Andes (REDSAV) was permanently installed in order to characterize the regional earthquake activity. The REDSAV is an array of 10 remote seismic stations that sends the seismic signals by analog telemetry to the central station, located in the city of Mérida, where the digitalization, automatic event detection in real time and the analysis and off-line processing of the seismic information is carried out. During the last 10 years important advances have been taken place in terms of its operativity, which includes a dynamic web site (http://lgula.ciens.ula.ve) with a catalog of western Venezuela earthquakes, where the user can visualize the seismograms, the P and S wave arrival time, the polarities and epicentral maps; moreover, it is possible to select events applying temporal, spatial and magnitute criteria. In this paper the technical characteristic of the equipment are described and the advances registered in the last years referring to the automatic acquisition system, processing of the information and seismologic catalog of the REDSAV, whose systematic use during a decade has permitted to gather the biggest information base of related with the seismicity of the south-western Venezuela.

  9. Application of the Orogenic Float Model for the Structural Evolution of the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Dhont, D.; Monod, B.; Hervouet, Y.; Klarica, S.

    2010-12-01

    The Venezuelan (or Mérida) Andes form a NE-SW-striking intracontinental orogen that started to uplift in the Middle Miocene due to E-W convergence between the Maracaibo block to the northwest and the Guyana shield to the southeast. Oblique collision resulted in strain partitioning accommodated by (1) transverse shortening along thrust faults bounding the belt on both flanks, (2) right-lateral slip along the Bocono fault running more or less along the chain axis and (3) tectonic escape of the Trujillo block moving towards the NE in between the Bocono and the N-S-striking sinistral Valera faults. Even though the surface geology of the Venezuelan Andes is well known, its structure at depth remains a matter of debate. Among the mechanisms that have proposed to account for the crustal architecture and evolution of the mountain belt, we develop the idea that the deformation process in this orogen is consistent with a model of orogenic float where the upper crust is decoupled from its underlying lithosphere above a large-scale mid-crustal detachment zone. According to this model, all the major faults involved in the strain partitioning sole into the detachment horizon and may therefore be considered as upper crustal faults. The integration of the orogenic float into a coherent evolutionary model provides further insight on both the crustal structure of the Venezuelan Andes and on the tectonic history of the region. A major reorganization in the crust occurred in the Early Pliocene when the Maracaibo block penetrated as a wedge into the Guyana crust. This event was accompanied by a rapid uplift of the Venezuelan Andes in association with the NE-ward crustal escape of the Trujillo block whose motion is accompanied by the lateral spreading of the upper crust.

  10. Spatial and temporal patterns of exhumation across the Venezuelan Andes: Implications for Cenozoic Caribbean geodynamics

    NASA Astrophysics Data System (ADS)

    Bermúdez, Mauricio A.; Kohn, Barry P.; van der Beek, Peter A.; Bernet, Matthias; O'Sullivan, Paul B.; Shagam, Reginald

    2010-10-01

    The Venezuelan Andes formed by complex geodynamic interaction between the Caribbean Plate, the Panamá Arc, the South American Plate and the continental Maracaibo block. We study the spatial and temporal patterns of exhumation across the Venezuelan Andes using 47 new apatite fission track (AFT) ages as well as topographic analyses. This approach permits the identification of at least seven tectonic blocks (Escalante, Cerro Azul, Trujillo, Caparo, Sierra Nevada, Sierra La Culata and El Carmen blocks) with contrasting exhumation and cooling histories. The Sierra Nevada, Sierra La Culata and El Carmen blocks, located in the central part of the Venezuelan Andes and separated by the Boconó fault system, cooled rapidly but diachronously during the late Miocene-Pliocene. Major surface uplift and exhumation occurred in the Sierra Nevada block since before 8 Ma. A second phase of uplift and exhumation affected the El Carmen and Sierra La Culata blocks to the north of the Boconó fault during the late Miocene-Pliocene. The highest topography and steepest relief of the belt coincides with these blocks. The Caparo and Trujillo blocks, located at the northeastern and southwestern ends of the orogen, cooled more slowly from the Oligocene to the late Miocene. These blocks are characterized by significantly lower mean elevations and slightly lower mean slopes than the central blocks. Unraveling the cooling history of the individual blocks is important to better understand the control of preexisting faults and regional Caribbean geodynamics on the evolution of the Venezuelan Andes. Our data indicate a strong control of major preexisting fault zones on exhumation patterns and temporal correlation between phases of rapid exhumation in different blocks with major tectonic events (e.g., collision of the Panamá arc; rotation of the Maracaibo block).

  11. Linked basin sedimentation and orogenic uplift: The Neogene Barinas basin sediments derived from the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Erikson, Johan P.; Kelley, Shari A.; Osmolovsky, Peter; Verosub, Kenneth L.

    2012-11-01

    The Venezuelan Andes are an asymmetric, doubly vergent orogen that is flanked on its southeastern side by the Barinas basin. Analyses of sedimentary facies, sandstone petrography, apatite fission-tracks, and magnetostratigraphy were completed on a 1750-m section of the syn-orogenic Neogene Parángula and Río Yuca formations in the Barinas side foothills of the Venezuelan Andes. Our sedimentary facies analyses record a progression of sedimentary environments from floodplain and floodplain channel deposits through the 560-m thick Parángula Formation transitioning to distal alluvial fan deposits in the lower Río Yuca Formation and finally to an alternation of distal alluvial fan and two, ˜100-m thick organic-rich lacustrine deposits in the upper third of the section. Major- and minor-mineral petrographic analysis reveals unroofing of the Venezuelan Andes, with quartz arenite composition low in the section succeeded by metamorphic and igneous clasts and potassium feldspar appearing near the base of the Río Yuca Formation. Apatite fission-track (AFT) analysis of sandstones and pebbles generated ages of 11.2 ± 1.3 - 13.8 ± 2.0 Ma over ˜1100 m of stratigraphic section. Thermal modeling of the detrital AFT and vitrinite data from the lower Río Yuca Formation indicates exhumation of the source area was occurring by 12-13 Ma, surface exposure at 10-9 Ma, maximum burial by 4-2 Ma and exhumation of the sedimentary package starting 3-2 Ma. Accumulation of the Río Yuca Formation is contemporaneous with a basinward migration of the deformation front. Regional considerations indicate that the Venezuelan Andes evolved from a primarily singly vergent orogen to its current double vergence over the interval of Neogene-Quaternary sedimentation.

  12. Toward quantifying geomorphic rates of crustal displacement, landscape development, and the age of glaciation in the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.; Aranguren, Reina; Rengifo, Martin; Owen, Lewis A.; Caffee, Marc W.; Murari, Madhav Krishna; Pérez, Omar J.

    2012-03-01

    We present the results of dating glacial landforms in Venezuela using 10Be terrestrial cosmogenic nuclide (TCN) analysis and optical stimulated luminescence (OSL). Boulders on the La Victoria and Los Zerpa moraines of the Sierra Nevada that mark the extent of the local last glacial maximum (LLGM) yield 10Be TCN surface exposure ages of 16.7 ± 1.4 ka (8 samples). About 25 km to the west in the drainage basin of the Río Mucujún, 10Be TCN dates for boulders on moraines at La Culata in the Sierra Nevada Norte yield a younger average age of 15.2 ± 0.9 ka (8 samples). The data suggest that glaciation across the Venezuelan Andes during the LLGM was asynchronous. The LLGM in Venezuela may be broadly concurrent with Heinrich Event 1 at ~ 16.8 ka, implying that glaciation here is dominantly temperature driven. A moraine inset into the older laterofrontal moraines of La Culata has an age of 14.1 ± 1.0 ka (5 samples); it may have been deposited by a small Late Glacial readvance. Right-lateral offsets of the La Victoria and Los Zerpa moraines by the Boconó fault are each ~ 100 m. The 10Be TCN based Boconó fault slip rate is about <~5.5 to 6.5 mm a- 1, notably less than the total right-lateral slip of 12 ± 2 mm a- 1 of shear documented across the Andes from geodesy. The 10Be TCN dating of boulders on a faulted alluvial fan along the northwestern range front at Tucanízón yields a late Pleistocene uplift rate of the Andes at between ~ 1.7 ± 0.7 mm a- 1. Glacial outwash has produced valley-fill sequences within the central Andean valley along the trace of the Boconó fault and Río Chama. The valley-fill has been incised to produce the ‘meseta', a terrace surface that sits > 100 m above the Río Chama and on which the major city of Mérida is built. Geomorphic observations indicate that the meseta deposits were largely derived from the glaciers of La Culata. The OSL dating suggests that the final aggradation of the valley-fill deposits occurred rapidly over a period of

  13. 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.

  14. Structural Evolution of the Central Venezuelan Andes: Changes From Compression to Strike-slip and Extension

    NASA Astrophysics Data System (ADS)

    Hervouet, Y.; Dhont, D.; Backe, G.

    2006-12-01

    The Venezuelan Andes form a N50°E-trending belt extending from the colombian border in the SW to the Caribbean sea in the NE. The belt is 100 km wide and its highest summits reach 5000 m in its central part. Uplift of the belt is a consequence of the relative convergence between the triangular-shaped Maracaibo crustal block on the west and the Guyana shield belonging to South America. The Maracaibo block is cut by a series of strike-slip faults separating several crustal units. Among these, the easternmost Trujillo triangular block is limited on the west by the N-S left-lateral Valera fault and on the south-east by the NE-trending right-lateral Bocono fault. Our methodology, based on the analysis of radar satellite and digital elevation model imagery and implemented by structural field work and the compilation of seismotectonic data, presents a new understanding of the tectonic evolution of the Venezuelan Andes during the Neogene-Quaternary. We have characterized three stages of deformation. The first, Mio-Pliocene in age, corresponds to the NW-SE Andean compression responsible for the uplift of the Venezuelan Andes. The second tectonic stage is consitent with a strike-slip regime of deformation marked by shearing along the Bocono and Valera faults and hence individualizing the Trujillo block, which has been cut into two smaller triangular wedges. This strike-slip faulting- dominated compressional-extensional tectonic regime started at some point between the Pliocene and the Quaternary and allowed the Trujillo crustal block to move towards the NE. The third stage of deformation corresponds to extension in the Trujillo block and is still active today. The present-day distribution of the deformation in the Venezuelan Andes is consistent with strain partitioning. While compression is restricted on both flanks of the belt, strike-slip and extension occurs in the central part of the mountain range. Extension is associated with the motion of crustal blocks moving

  15. Active faulting in the Southwestern Venezuelan Andes and Colombia borderland

    SciTech Connect

    Singer, A.; Beltran, C.; Lugo, M. , Caracas )

    1993-02-01

    In the southern Andes, the Bocono fault shows a progressive disactivation of its right lateral movement, resulting from its attenuation against the transversal system of Bramon and its kinematic connection to the [open quotes]Pamplona indenter,[close quotes] considered as a part of the plate boundary between the Caribbean and South America. Near the Colombian frontier, the velocity of Bocono fault is probably less than 1 mm/yr. Such a decrease is explained because an increasing amount of the 1 cm/yr slip movement of the northern part of the fault is absorbed through a complex branching of the active trace, southwest Merida. Another significative amount of the rate movement of Bocono fault, considered as plate boundary, results absorbed by subparallel active faulting systems located to the east (Uribante and Caparo Systems) and to the west sides (San Simon-Seboruco, and San Pedro-Aguas Calientes-La Don Juana systems). The last system, extending beyond the frontier, shows a particular seimotectonic importance, as a probable source of the 1875 Cucata earthquake. In this way, the weight of the southwestern end of Bocono fault as a seismic source loses importance respect to the northern segment located between la Grita and Merida where the 1610 and 1894 earthquakes occurred, and also as compared to the faults that define the [open quotes]Pamplona indenter[close quotes] like probable source for several other destructive earthquakes.

  16. Orogenic Float Model: an Explanation for the Dynamics of the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Monod, B.; Dhont, D.; Hervouet, Y.

    2008-12-01

    The Venezuelan (or Merida) Andes are a NE-trending intracontinental orogen that started to rise from the late Miocene due to the E-W far field convergence between the Maracaibo block to the northwest and the Guyana shield to the southeast. Oblique convergence is responsible for strain partitioning with thrusting along both foreland basins and right-lateral strike-slip faulting along the NE-SW Bocono fault cutting the Venezuelan Andes along-strike. The central part of the belt is also cut by the N-S left-lateral strike-slip Valera fault that branches the Bocono fault in the triple junction geometry, favoring the crustal escape of the Trujillo triangular block towards the NE. Onset of strike-slip motion along major faults and their geometry at depth remains a matter of debate. Our work, based on the integration of geologic and geophysical data aims to better constrain both the geometry and the tectonic evolution of the major tectonic structures. We use the orogenic float model (Oldow et al., 1990) as a first hypothesis to construct two NW-SE trans-Andean crustal scale balanced sections. The late Neogene-Quaternary shortening varies from 40 km in the south to 30 km in the north across the Trujillo block, indicating that a quarter of the deformation seems to be absorbed by the tectonic escape process. The cross-sections served also as the basis for the building of a 3-D geologic model of the Venezuelan Andes, permitting to clearly understand the link and geometry of the faults at depth. The decollement level used for the orogenic float model, located at 20 km depth, is crucial for the motion of the Trujillo block. Both the Bocono and Valera faults have listric shapes connecting to the decollement level. The connexion of the two fault surfaces forms a hinge line dipping towards the north in a geometry favoring the escape of the Trujillo block and allowing the gravity forces to play an important role in the process. Oldow J. S., Bally A. W., Ave Lallemant H. G., 1990

  17. 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.

  18. 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.

  19. 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

  20. 3D geological modeling of the Trujillo block: Insights for crustal escape models of the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Dhont, Damien; Monod, Bernard; Hervouët, Yves; Backé, Guillaume; Klarica, Stéphanie; Choy, José E.

    2012-11-01

    The Venezuelan Andes form a N50°E-trending mountain belt extending from the Colombian border in the SW to the Caribbean Sea in the NE. The belt began to rise since the Middle Miocene in response to the E-W collision between the Maracaibo block to the NW and the Guyana shield belonging to South America to the SE. This oblique collision led to strain partitioning with (1) shortening along opposite-vergent thrust fronts, (2) right-lateral slip along the Boconó fault crossing the belt more or less along-strike and (3) crustal escape of the Trujillo block moving towards the NE in between the Boconó fault and the N-S-striking left-lateral Valera fault. The geology of the Venezuelan Andes is well described at the surface, but its structure at depth remains hypothetic. We investigated the deep geometry of the Mérida Andes by a 3D model newly developed from geological and geophysical data. The 3D fault model is restricted to the crust and is mainly based on the surface data of outcropping fault traces. The final model reveals the orogenic float concept where the mountain belt is decoupled from its underlying lithosphere over a horizontal décollement located either at the upper/lower crust boundary. The reconstruction of the Boconó and Valera faults results in a 3D shape of the Trujillo block, which floats over a mid-crustal décollement horizon emerging at the Boconó-Valera triple junction. Motion of the Trujillo block is accompanied by a widespread extension towards the NE accommodated by normal faults with listric geometries such as for the Motatan, Momboy and Tuñame faults. Extension is explained by the gravitational spreading of the upper crust during the escape process.

  1. 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.

  2. 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.

  3. 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

  4. Spatial and temporal relationships between compression, strike-slip and extension in the Central Venezuelan Andes: Clues for Plio-Quaternary tectonic escape

    NASA Astrophysics Data System (ADS)

    Backé, Guillaume; Dhont, Damien; Hervouët, Yves

    2006-10-01

    The geometry of tectonic structures, attributed to the Neogene-Quaternary time interval, is described in the active setting of the Venezuelan Andes. Our methodology is based on the analysis of radar satellite and Digital Elevation Model imagery, complemented by structural fieldwork and the compilation of seismotectonic data to make a structural analysis on a regional scale. Radar images provide first class data for morphostructural analysis in areas of dense vegetation and frequent cloud covering, like the Venezuelan Andes. We focused our analysis in the Burbusay-Río Momboy and Boconó faults corner located in the central part of the belt. We have described three stages of deformation during the Neogene-Quaternary. The first one, Mio-Pliocene in age, is a NW-SE compression responsible for the uplift of the Venezuelan Andes. The second tectonic stage corresponds to a strike-slip regime of deformation marked by shearing along the Boconó, Burbusay and Valera faults, which separates two triangular wedges in the larger Trujillo block. This strike-slip faulting-dominated compressional-extensional tectonic regime allowed the Trujillo crustal block to move towards the NE. Wrenching has therefore started at some point between the Pliocene and the Quaternary. These two tectonic events are consistent with ongoing strain partitioning in the Venezuelan Andes. The third stage corresponds to extensional deformation limited to the Trujillo block and is still active today. Extension is associated with the motion of crustal blocks moving relative to each other, probably above the upper-lower crust boundary. Such extensional deformation can be understood considering that the crust extends and stretches at the same time as it moves towards the NE. The combination of both horizontal lateral motion and extension is characteristic of a tectonic escape process. The northeastward escape of the Trujillo block, which belongs to the larger North Andes block, occurs as a result of the

  5. Metre-scale cyclicity in Permian ramp carbonates of equatorial Pangea (Venezuelan Andes): Implications for sedimentation under tropical Pangea conditions

    NASA Astrophysics Data System (ADS)

    Laya, Juan Carlos; Tucker, Maurice E.; Perez-Huerta, Alberto

    2013-06-01

    Palmarito strata in the mid-Permian of the Venezuelan Andes show three different types of metre-scale cycle: Type A cycles are mixed clastic-carbonate, shallowing-upward peritidal cycles. The upper boundaries of the cycles are exposure surfaces with calcrete. This kind of cycle shows a significant degree of randomness in its thickness pattern and this is attributed to an autocyclic origin through tidal-flat progradation, and variations in carbonate productivity and clastic input to the depositional area. Type B cycles consist entirely of shallow subtidal facies with a shallowing-upward arrangement and an alternation between heterozoan and photozoan assemblages. Type C cycles were deposited in a middle to outer ramp setting and are characterized by a heterozoan assemblage and shallowing-upward trends that includes spiculitic wackestone-packstone passing up into neomorphic bioclastic wackestone or bioclastic crinoidal-bryozoan wackestone-packstone. All cycles are interpreted as 4th-5th order (104 to 105 years duration) and some can be linked to Milankovitch orbital rhythms, notably short eccentricity (~ 100,000 years). Overall, the origin of the Palmarito cycles was a complex combination of autocyclic and allocyclic controls; however, the evidence suggests that cycles in the lower part of the succession were dominated more by autocyclic processes whereas those in the upper part were more the result of allocyclic controls. Climate-driven processes, such as migration of the intertropical convergence one and the waxing and waning of polar ice-caps, had significant effects on deposition of the Palmarito succession and the cycles therein, controlling the clastic sediment supply, nutrient availability and thus carbonate production, and sea-level change, and these factors determined the vertical stacking pattern of the cycles.

  6. Stratotype for the Mérida Glaciation at Pueblo Llano in the northern Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Mahaney, W. C.; Milner, M. W.; Voros, J.; Kalm, V.; Hütt, G.; Bezada, M.; Hancock, R. G. V.; Aufreiter, S.

    2000-12-01

    The Mérida Glaciation (cf. Wisconsinan, Weichselian) as proposed by Schubert (1974b) culminated at about 18 ka during the last glacial maximum (LGM) and ended at about 13 ka as indicated by 14C dating and correlation with the Cordillera Oriental of Colombia. Moraines of an early stade of Mérida Glaciation reached to 2800 m a.s.l. and were largely overrun or eradicated by the maximum Wisconsinan advance (LGM); where they outcrop, the older moraines are characterized by eroded, weathered glacial diamictons and outwash fans. At Pueblo Llano in the central Mérida Andes (Cordillera de Trujillo), older to younger beds of contorted glacitectonized diamict, overlying beds of bouldery till and indurated outwash, all belong to the early Mérida stade. Overlying the early Mérida stade, deposits of rhythmically bedded glaciolacustrine sediments are in turn overlain with contorted sand and silt beds capped with outwash. Above the outwash terrace a loop moraine of LGM age completely encircles the margins of the basin. A stream cut exposed by catastrophic (tectonic or surge?) release of meltwater displays a lithostratigraphic succession that is bereft of organic material for radiocarbon dating. Five optically-stimulated luminescence (OSL) dates place the maximum age of the lowest till at 81 ka. Particle size distributions allow clear distinctions between major lithic units. Heavy mineral analysis of the middle and lower coarse units in the section provide information on sediment sourcing and on major lithostratigraphic divisions. Trace element concentrations provide information on the relative homogeneity of the deposits. The HREE (heavy rare earth element) concentrations allow discrimination of the lower till from the rest of the section; the LREE (light rare earth element) concentrations highlight differences between the lower till, LGM till, and the rest of the section.

  7. 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.

  8. 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.

  9. Andes

    Atmospheric Science Data Center

    2013-04-18

    article title:  The Andes in True Color, Stereo, and Relief     Left: True Color Image View true color full resolution image in JPEG format ... view afforded by the stereo anaglyph image (viewed with red/blue glasses, with the red lens over the left eye), it is possible to ...

  10. [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.

  11. 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

  12. 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.

  13. 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.

  14. Dynamics and Upper Mantle Structure Beneath the Northwestern Andes: Subduction Segments, Moho Depth, and Possible Relationships to Mantle Flow

    NASA Astrophysics Data System (ADS)

    Monsalve, G.; Yarce, J.; Becker, T. W.; Porritt, R. W.; Cardona, A.; Poveda, E.; Posada, G. A.

    2014-12-01

    The northwestern South American plate shows a complex tectonic setting whose causes and relationship to mantle structure are still debated. We combine different techniques to elucidate some of the links between slabs and surface deformation in Colombia. Crustal structure beneath the Northern Andes was inferred from receiver functions where we find thicknesses of nearly 60 km beneath the plateau of the Eastern Cordillera and underneath the southern volcanic area of the Central Cordillera. We infer that such crustal thickening resulted from shortening, magmatic addition, and accretion-subduction. Analyses of relative teleseismic travel time delays and estimates of residual surface topography based on our new crustal model suggest that there are at least two subduction segments underneath the area. The Caribbean slab lies at a low angle beneath northernmost Colombia and steepens beneath the Eastern Cordillera. Such steepening is indicated by negative travel time relative residuals in the area of the Bucaramanga Nest, implying a cold anomaly in the upper mantle, and by positive residual topography just off the east of this area, perhaps generated by slab-associated return flow. Results for the western Andes and the Pacific coastal plains are consistent with "normal" subduction of the Nazca plate: travel time relative residuals there are predominantly positive, and the residual topography shows an W-E gradient, going from positive at the Pacific coastline to negative at the Magdalena Valley, which separates the eastern cordillera from the rest of the Colombian Andean system. Azimuthal analysis of relative travel time residuals further suggests the presence of seismically slow materials beneath the central part of the Eastern Cordillera. Azimuthal anisotropy from SKS splitting in that region indicates that seismically fast orientations do not follow plate convergence, different from what we find for the western Colombian Andes and the Caribbean and Pacific coastal plains

  15. 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

  16. Geological history of the Cretaceous ophiolitic complexes of northwestern South America (Colombian Andes)

    NASA Astrophysics Data System (ADS)

    Bourgois, Jacques; Toussaint, Jean-François; Gonzalez, Humberto; Azema, Jacques; Calle, Bernardo; Desmet, Alain; Murcia, Luis A.; Acevedo, Alvaro P.; Parra, Eduardo; Tournon, Jean

    1987-12-01

    The Western Cordillera of Colombia was formed by intense alpine-type nappe-forming folding and thrusting. The Cretaceous (80-120 Ma B.P.) tholeiitic material of the Western Cordilleran nappes has been obducted onto the Paleozoic and Precambrian polymetamorphic micaschists and gneiss of the Central Cordillera. Near Yarumal, the Antioquia batholith (60-80 Ma B.P.) intrudes both obducted Cretaceous oceanic material and the polymetamorphic basement rock of the Central Cordillera. Therefore, nappe emplacement and obduction onto the Central Cordillera occurred during Late Senonian to Early Paleocene. The nappes travelled from northwest to southeast so that the highest unit, the Rio Calima nappe therefore has the most northwestern source, whereas the lowest units originated from a more southeastward direction. Sedimentological analysis of the volcanoclastic and sandy turbidite material from each unit suggests a marginal marine environment. During Cretaceous times the opening of this marginal sea, from now on called the "Colombia marginal basin", probably originated by detachment of a block from the South American continent related to the Farallon-South America plate convergence. In the Popayan area (southern Colombia), the Central Cordilleran basement exhibits glaucophane schist facies metamorphism. This high pressure low temperature metamorphism is of Early Cretaceous (125 Ma B.P.) age and is related to an undated metaophiolitic complex. The ophiolitic material originating from the Western Cordilleran is thrust over both the blueschist belt and the metaophiolitic complex. These data suggest that the "Occidente Colombiano" suffered at least two phases of ophiolitic obduction during Mesozoic time.

  17. 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

  18. Detrital zircon fission-track thermochronology and magnetic fabric of the Amagá Formation (Colombia): Intracontinental deformation and exhumation events in the northwestern Andes

    NASA Astrophysics Data System (ADS)

    Piedrahita, V. A.; Bernet, M.; Chadima, M.; Sierra, G. M.; Marín-Cerón, M. I.; Toro, G. E.

    2017-07-01

    New detrital zircon-fission track (ZFT) and magnetic fabric data are presented to constrain the time of deposition, provenance and deformation of the of Lower and Upper members of the Amagá Formation in the Amagá Basin. The Amagá Basin is located in the northern Andes, between the Western and Central Cordilleras of Colombia. The Amagá Formation was deposited in a transpressive geodynamic context and is allegedly synchronous with tectonic events such as the Andean orogeny and the Panama-Choco Block collision with the northwestern South American Plate. Detrital ZFT data confirm an Oligocene age for the Lower Member and a middle-Miocene age for the Upper Member of the Amagá Formation. In addition to constraining the depositional age, the ZFT data presented in this study also reflect Paleocene-Eocene, late to early Oligocene and late to middle Miocene cooling in sediment source areas mainly located in the Central and Western Cordilleras of Colombia. These ages can be associated with regional exhumation events in the central and northern Andes of South America. Collisional stages of the Panama-Choco Block against northwestern South America, subduction of the Farallon-Nazca Plate and strike-slip reactivation periods of the Cauca-Romeral fault system, caused NW-SE compression and NE-SW simple shear in the Amagá Basin. This deformational regime, identified by magnetic fabric data, induces syn- and post-depositional deformation over the Amagá Formation.

  19. Diversity of culturable bacteria recovered from Pico Bolívar's glacial and subglacial environments, at 4950 m, in Venezuelan tropical Andes.

    PubMed

    Rondón, Johnma; Gómez, Wileidy; Ball, María M; Melfo, Alejandra; Rengifo, Marcos; Balcázar, Wilvis; Dávila-Vera, Delsy; Balza-Quintero, Alirio; Mendoza-Briceño, Rosa Virginia; Yarzábal, Luis Andrés

    2016-11-01

    Even though tropical glaciers are retreating rapidly and many will disappear in the next few years, their microbial diversity remains to be studied in depth. In this paper we report on the biodiversity of the culturable fraction of bacteria colonizing Pico Bolívar's glacier ice and subglacial meltwaters, at ∼4950 m in the Venezuelan Andean Mountains. Microbial cells of diverse morphologies and exhibiting uncompromised membranes were present at densities ranging from 1.5 × 10(4) to 4.7 × 10(4) cells/mL in glacier ice and from 4.1 × 10(5) to 9.6 × 10(5) cells/mL in subglacial meltwater. Of 89 pure isolates recovered from the samples, the majority were eurypsychrophilic or stenopsychrophilic, according to their temperature range of growth. Following analysis of their 16S rDNA nucleotidic sequence, 54 pure isolates were assigned to 23 phylotypes distributed within 4 different phyla or classes: Beta- and Gammaproteobacteria, Actinobacteria, and Bacteroidetes. Actinobacteria dominated the culturable fraction of glacier ice samples, whereas Proteobacteria were dominant in subglacial meltwater samples. Chloramphenicol and ampicillin resistance was exhibited by 73.07% and 65.38%, respectively, of the subglacial isolates, and nearly 35% of them were multiresistant. Considering the fast rate at which tropical glaciers are melting, this study confirms the urgent need to study the microbial communities immured in such environments.

  20. Soil stratigraphy and plant soil interactions on a Late Glacial Holocene fluvial terrace sequence, Sierra Nevada National Park, northern Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Mahaney, William C.; Dirszowsky, Randy W.; Milner, Michael W.; Harmsen, Rudolf; Finkelstein, Sarah A.; Kalm, Volli; Bezada, Maximilano; Hancock, R. G. V.

    2007-01-01

    Analysis of a flight of alluvial terraces in the Sierra Nevada National Park near Pico Mucuñuque in the Eastern Mérida Andes has yielded information on geomorphic, pedogenic, and vegetational changes from Late Glacial time to the present. The terraces formed in large part due to stream incision/migration triggered by neotectonic uplift (>7000 yr BP) of a Late Glacial/Early Holocene glaciolacustrine lithosequence and, with the exception of the oldest/highest terrace, exhibit near-uniform lithology/parent materials. Soils developed in the terrace materials range from thin, weakly developed profiles (O/C/Cu horizons) to Entisols with O/Ah/Cox/Cu horizons and similar buried counterparts representing former short periods of floodplain stability or slow aggradation. The buried soils provide organic-rich material that yields radiocarbon ages, which provide time constraints on individual pedons and the geomorphic development of the site. Iron and aluminum extracts of soil matrix material provide information on the formation and accumulation of goethite and hematite, the relative accumulation of ferrihydrite (gain/loss), and the downward translocation of organically complexed Al as a function of soil development and age. SEM analysis of heavy mineral grains indicates varying material sources and degrees of weathering in the soil chronosequence. A qualitative study of plant functional types across the terrace sequence shows that older surfaces support greater plant diversity. The study also suggests ways in which the plant communities influence soil development at the site through varying organic matter inputs and varying soil moisture use by specific species (e.g., ferns on the oldest terrace), which may explain the absence of B horizons in the Late Pleistocene/Early Holocene soils.

  1. Compositional Trends of Cretaceous Conglomerate Provenance: Tracing The Evolving Nature of Tectonic Environments in the Northwestern Colombian Andes

    NASA Astrophysics Data System (ADS)

    Patino, A. M.; Zapata, S.; Cardona, A.; Jaramillo, J. S.

    2014-12-01

    The composition and provenance of the sedimentary record is a sensible marker of the evolving nature of source , basin paleogeography and tectonic assemblage. The Cretaceous geological evolution of the northern Andes is characterized by the succession of different tectonic environments that include: An early Cretaceous magmatic quiescence that follow former Jurassic arc magmatism, Albian-Aptian subduction resume and associated arc - back-arc formation and the late Cretaceous collision with an allocthonous oceanic arc that marks the beginning of the Andean orogeny. Such tectonic evolution had been mostly reconstructed from the magmatic record or the stratigraphic analysis of inland basin far from the arcs and suture zones. Along the western flank of the central cordillera outcrops two different stratigraphic units with notable differences in the provenance and timing of accumulation. The Abejorral Formation is the oldest sedimentary sequence (Albian-Aptian) that discordantly overlies the Triassic continental margin. this unit include two lithofacies clearly distinguishable, a lithofacies consist mostly of conglomerate, characterized by abundant quartz content , low compaction, rounded clasts and moderate sorting ; and the other is a interbedded of fine size sandstone, mudstone and chert; also with abundant quartz content further muscovite, containing basement and volcanic material . To the west, sedimentary rocks including within the Quebradagrande Formation conform a turbidite sequence with a well defined Bouma type succession that concordantly overlied a Campanian marine volcanic arc succession. The conglomerates associated to this unit are characterized by containing mainly sedimentary and volcanic rock fragments ,high compaction, subrounded clast, and low sorting. This sequence is overlying by the volcanic component in a concord contact. Whereas the Albian-Aptian record of the Abejorral Formation exhibit the unroofing of the continental basement and deepening of

  2. Venezuelan solution

    SciTech Connect

    Not Available

    1984-05-16

    Of the three most famous cases of internal market price subsidies, Mexico, Venezuela, and Saudi Arabia, only Saudi Arabia remains the one oil-exporting developing country persisting in this domestic price policy. Mexico took the bold decision of hiking prices several times since early 1982, but this is the first such drastic action by Venezuela. Suffering both burgeoning foreign debt and reduced oil-export revenues, Venezuela has taken the difficult decision of hiking internal market prices for two important purposes: to curtail almost rampant consumption increases, and to increase oil-industry revenues. Internal market analysts have for years voiced their concern about the consequences of maintaining the deep subsidies, and many studies have gathered dust on the shelf. It was the external shocks hitting the country broadside that finally forced the government to act: world recession, lower oil demand and prices, and the growing pressure to invest in the future of the oil industry in the face of the national foreign debt all brought an end to such a cheap, if not free, lunch for Venezuelan consumers. A chart illustrates how each of eight light petroleum product prices were increased. This issue includes the fuel price/tax series and the industrial fuel prices for May 1984 for countries of the Eastern Hemisphere.

  3. [Venezuelan Virology Network].

    PubMed

    Añez, Germán

    2005-03-01

    In November 2004, sponsored by the World Bank, the Venezuelan Foundation of Science, Technology and Innovation (Fonacit) and the Venezuelan Institute of Scientific Research (IVIC), delegates from the different virology research groups of the country, met in Caracas-Venezuela, with the aim to establish the "Venezuelan Virology Network". The symposium entitled "Molecular biology applied to virus of health importance in Venezuela", was divided into three areas, including human and animals viruses related to public health: 1) Dengue, others arboviruses and Hemorrhagic Fevers; 2) diarrhea-related and others veterinary viruses and 3) Hepatitis, HIV and others sexually transmitted viruses. This symposium allowed the delegates to evaluate the current strengths, weaknesses and needs of the different laboratories, becoming evident the necessity of developing collaborative work between the groups that share the same interests or lines of research; and also their need to exchange technical resources, human and bibliographical material and consequently, avoiding the duplication of efforts and the unnecessary cost of resources. One of the main strengths of Venezuelan virology is the presence, in most laboratories, of researchers with studies of fourth level and multidisciplinary teams of work. We aspire to achieve the raised objectives in the event, to the benefit of our virology and even more important, of our people.

  4. Venezuelan haemorrhagic fever.

    PubMed

    Salas, R; de Manzione, N; Tesh, R B; Rico-Hesse, R; Shope, R E; Betancourt, A; Godoy, O; Bruzual, R; Pacheco, M E; Ramos, B

    1991-10-26

    An outbreak of severe haemorrhagic illness began in the municipality of Guanarito, Portuguesa State, Venezuela, in September, 1989. Subsequent detailed study of 15 cases confirmed the presence of a new viral disease, designated Venezuelan haemorrhagic fever. Characteristic features are fever, toxicity, headache, arthralgia, diarrhoea, conjunctivitis, pharyngitis, leucopenia, thrombocytopenia, and haemorrhagic manifestations. Other features include facial oedema, cervical lymphadenopathy, nausea/vomiting, cough, chest or abdominal pain, and convulsions. The patients ranged in age from 6 to 54 years; all were residents of rural areas in central Venezuela, and 9 died. Infection with Guanarito virus, a newly recognised arenavirus, was shown by direct culture or by serological confirmation in all cases. Epidemiological studies suggest that the disease is endemic in some rural areas of central Venezuela and that it is rodent-borne. Venezuelan haemorrhagic fever has many similarities to Lassa fever and to the arenavirus haemorrhagic fevers that occur in Argentina and Bolivia.

  5. Group updates Gravity Database for central Andes

    NASA Astrophysics Data System (ADS)

    MIGRA Group; Götze, H.-J.

    Between 1993 and 1995 a group of scientists from Chile, Argentina, and Germany incorporated some 2000 new gravity observations into a database that covers a remote region of the Central Andes in northern Chile and northwestern Argentina (between 64°-71°W and 20°-29°S). The database can be used to study the structure and evolution of the Andes. About 14,000 gravity values are included in the database, including older, reprocessed data. Researchers at universities or governmental agencies are welcome to use the data for noncommercial purposes.

  6. ASTER Andes

    NASA Image and Video Library

    2000-10-06

    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. http://photojournal.jpl.nasa.gov/catalog/PIA02654

  7. 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

  8. VENEZUELAN EQUINE ENCEPHALOMYELITIS IN MAN

    PubMed Central

    Casals, J.; Curnen, Edward C.; Thomas, Lewis

    1943-01-01

    A filterable agent was isolated from the blood and from washings of the upper respiratory passages of a young laboratory worker during a mild, acute, febrile illness. This agent was identified as a strain of Venezuelan equine encephalomyelitis virus. Circulating specific complement-fixing and neutralizing antibodies not present in sera withdrawn during the acute phase of illness were demonstrated in sera obtained during convalescence. A fellow laboratory worker who became similarly ill simultaneously also developed during convalescence specific circulating antibodies not present prior to illness. PMID:19871301

  9. 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.

  10. 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

  11. Andes: An intelligent homework helper

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

    Andes (www.andes.pitt.edu) is an intelligent tutor homework system designed for use as the homework portion of an introductory physics course. It encourages students to use good problem solving techniques and provides immediate feedback on each step of a problem solution along with hints on request. I will discuss how Andes works, from a student perspective, and present research demonstrating its effectiveness as a pedagogical tool. Then, I will discuss using Andes as a tool for conducting education research, briefly reviewing several studies conducted using Andes. Finally, I will show how logs of student solutions to Andes problems can be used to develop cognitive models of student learning.

  12. 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.

  13. Population genetic structure of Venezuelan chiropterophilous columnar cacti (Cactaceae).

    PubMed

    Nassar, Jafet M; Hamrick, J L; Fleming, Theodore H

    2003-11-01

    We conducted allozyme surveys of three Venezuelan self-incompatible chiropterophilous columnar cacti: two diploid species, Stenocereus griseus and Cereus repandus, and one tetraploid, Pilosocereus lanuginosus. The three cacti are pollinated by bats, and both bats and birds disperse seeds. Population sampling comprised two spatial scales: all Venezuelan arid zones (macrogeographic) and two arid regions in northwestern Venezuela (regional). Ten to 15 populations and 17-23 loci were analyzed per species. Estimates of genetic diversity were compared with those of other allozyme surveys in the Cactaceae to examine how bat-mediated gene dispersal affects the population genetic attributes of the three cacti. Genetic diversity was high for both diploid (P(s) = 94.1-100, P(p) = 56.7-72.3, H(s) = 0.182-0.242, H(p) = 0.161-0.205) and tetraploid (P(s) = 93.1, P(p) = 76.1, H(s) = 0.274, H(p) = 0.253) species. Within-population heterozygote deficit was detected in the three cacti at macrogeographic (F(IS) = 0.145-0.182) and regional (F(IS) = 0.057-0.174) levels. Low genetic differentiation was detected at both macrogeographic (G(ST) = 0.043-0.126) and regional (G(ST) = 0.009-0.061) levels for the three species, suggesting substantial gene flow among populations. Gene exchange among populations seems to be regulated by distance among populations. Our results support the hypothesis that bat-mediated gene dispersal confers high levels of genetic exchange among populations of the three columnar cacti, a process that enhances levels of genetic diversity within their populations.

  14. Andes Altiplano, South America

    NASA Image and Video Library

    1991-08-11

    STS043-151-159 (2-11 August 1991) --- This photograph looks westward over the high plateau of the southern Peruvian Andes west and north of Lake Titicaca (not in field of view). Lima, Peru lies under the clouds just north of the clear coastal area. Because the high Andes have been uplifted 10,000 to 13,000 feet during the past 20 million years, the rivers which cut down to the Pacific Ocean have gorges almost that deep, such as the Rio Ocona at the bottom of the photograph. The eastern slopes of the Andes are heavily forested, forming the headwaters of the Amazon system. Smoke from burning in the Amazon basin fills river valleys on the right side of the photograph. A Linhof camera was used to take this view.

  15. The ANDES underground laboratory

    NASA Astrophysics Data System (ADS)

    Bertou, X.

    2012-09-01

    The ANDES underground laboratory, planned for inclusion in the Agua Negra tunnel crossing the Andes between Argentina and Chile, will be the first deep underground laboratory in the southern hemisphere. It will be deep (1750 m of rock overburden), large (60 000 m3 of volume), and provide the international community with a unique site for testing dark-matter modulation signals. The site furthermore has a low nuclear reactor neutrino background and is of special interest to the geophysics sciences. The laboratory will be run as a multi-national facility, under a consortium of Latin-American countries. Its opening is expectedfor 2020.

  16. Genetic analysis of the Venezuelan Criollo horse.

    PubMed

    Cothran, E G; Canelon, J L; Luis, C; Conant, E; Juras, R

    2011-10-07

    Various horse populations in the Americas have an origin in Spain; they are remnants of the first livestock introduced to the continent early in the colonial period (16th and 17th centuries). We evaluated genetic variability within the Venezuelan Criollo horse and its relationship with other horse breeds. We observed high levels of genetic diversity within the Criollo breed. Significant population differentiation was observed between all South American breeds. The Venezuelan Criollo horse showed high levels of genetic diversity, and from a conservation standpoint, there is no immediate danger of losing variation unless there is a large drop in population size.

  17. 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

  18. A Statistical Analysis of Venezuelan Defense Spending.

    DTIC Science & Technology

    1985-03-01

    1954. 11. Costezano, V. and Casado, E.R., Venezuelan Education La Esfera Newspaper, Caracas, 1954. 12. Instituto Interamericano de Estadistica , America...en Cifras, 1974. 13. Instituto Interamericano do Estadistica , America en Cifras, 1974. 14. Furtado, C., Economic Development Of Latin America

  19. Tectonics and geodynamics of the Eastern Venezuelan Ranges

    SciTech Connect

    Roure, F. ); Passalacqua, H. ); Gou, I. )

    1993-02-01

    The eastern Venezuelan Ranges result from oblique convergence along the South American-Caribbean plate boundary, whose main surface expression is the El Pilar dextral strike-slip fault. Crustal scale balanced cross-sections have been here completed from available surface and subsurface data across this major transfer zone which links the oceanic subduction of the Lesser Antilles with the continental subduction of the Andes. The present geometries of the sectons show a major discrepancy between the cover and basement lengths, which could be explained by tectonic inheritance from the Tethyan margin. A careful analysis of both the chronostratigraphy and the internal geometry of the foredeep and piggy-back syntectonic deposits are also used to establish the kinematics of each individual structure. Basement involved is postulated for the Pirital Thrust which cuts previously emplaced cover structures like the El Furrial structural unit. Reactivation of ancient thrust faults occurs also at the rear of the Pirital out-of-sequence thrust in the west. As in the Alps or the Pyrenees, a high density intracrustal wedge is required to fit the gravimetric high imaged north of the Serrania; the solutions require a deep crustal root beneath the belt and a north-dipping South American Moho. A consistent geodynamical model, involving the north-dipping subduction of at least 70 km of South American continental lithosphere is thus proposed. An important strain partitioning occurs along the El Pilar Fault and underneath the deep crustal indenter (backstop), which decouples the south-verging allochthon of the Serrania from the north-dipping subducted South American lithosphere and from the eastward-migrating metamorphic belt.

  20. 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

  1. An overview of Venezuelan gas resources

    SciTech Connect

    Padua, J.A.

    1986-01-01

    This work begins with a historical account starting in 1918 and covers the production and utilization of the country's natural gas, as related to the operations of the Venezuelan oil and petrochemical industries and to the domestic market as a whole. This historical survey concludes with a detailed analysis of the activities conducted in 1985. Next, the estimated reserves of natural gas, both on and offshore is reviewed. This information is then analyzed as to the classification of these reserves, in terms of their probability of existence, their geographic location, and whether they are associated with oil. A forecast of production and demand for the country as a whole, from 1986 to 2005, is presented. This forecast incorporates the most probable scenario for the future of natural gas as an energy resource and raw material, based on the best current criteria. Conclusions are presented indicating that in the long term Venezuelan gas resources will be enough to cover internal and external demand.

  2. ASSESSMENT OF SOMATIC MATURATION OF VENEZUELAN ADOLESCENTS.

    PubMed

    Méndez Pérez, Betty; Marrodán Serrano, María Dolores; Prado Martínez, Consuelo; Aréchiga Viramontes, Julieta; Cabañas Armesillas, María Dolores

    2015-11-01

    beginning of adolescence comprises important physical modifications, which affects growth and changes in body composition, therefore it is important to consider maturation assessment. to develop a non-invasive method to assess maturity status in Venezuelan adolescents from peak height velocity (PHV) by means of anthropometric variables in a cross-sectional sample. data comprised 681 Venezuelan adolescents 9 up to 18 years of age. Mirwald equation was applied to derived PHV. Regression analysis was used in order to build a model for Venezuelan sample as well as, ROC curves to assess sensitivity and specificity of anthropometric variables. the predictive equations for both sexes, exhibited a high determination coefficient (< 0.99) and a minimal estimation error (0.06). Mean decimal age at categories of PHV obtained by both equations: criterion and model, were very similar (13.27 vs. 13.39) for boys, and (11.62 vs. 11.77) for girls. Bland-Altman plot showed a tight concordance between the two equations and all anthropometric indices, exhibited high area under the curve > 0.75, specially sitting height. in Venezuela, there is little work based on longitudinal studies of the maturation status. Giving the difficult faced in the longitudinal studies recent works have been used cross-sectional methodology in the assessment of the somatic maturation, both in non athletic and athletic populations. This study provides predicting equations for the assessment of the somatic maturation adjusted to Venezuelan population developed from Mirwald equation, which may be used to aid in evaluation of nutritional and general health, as well as, a reduction of risks associated with miss-classification for chronological age. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  3. 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.

  4. Rise of the Andes.

    PubMed

    Garzione, Carmala N; Hoke, Gregory D; Libarkin, Julie C; Withers, Saunia; MacFadden, Bruce; Eiler, John; Ghosh, Prosenjit; Mulch, Andreas

    2008-06-06

    The surface uplift of mountain belts is generally assumed to reflect progressive shortening and crustal thickening, leading to their gradual rise. Recent studies of the Andes indicate that their elevation remained relatively stable for long periods (tens of millions of years), separated by rapid (1 to 4 million years) changes of 1.5 kilometers or more. Periodic punctuated surface uplift of mountain belts probably reflects the rapid removal of unstable, dense lower lithosphere after long-term thickening of the crust and lithospheric mantle.

  5. Important Considerations in the Counseling Process of Immigrant Venezuelan Families.

    ERIC Educational Resources Information Center

    Guanipa, Carmen; Nolte, Linda; Guanipa, Jose

    2002-01-01

    Assessment of immigrant Venezuelan families may be achieved effectively when therapists are able to delineate, without stereotyping, the contributions of culture to the presenting complaint and symptomatology. This article presents therapeutic considerations for relating to Venezuelan families. Guidelines for gathering clinical information are…

  6. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine, Venezuelan, shall be prepared from virus-bearing cell culture fluids. Only Master Seed which has been...

  7. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine, Venezuelan, shall be prepared from virus-bearing cell culture fluids. Only Master Seed which has been...

  8. 9 CFR 113.308 - Encephalomyelitis Vaccine, Venezuelan.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Live Virus Vaccines § 113.308 Encephalomyelitis Vaccine, Venezuelan. Encephalomyelitis Vaccine, Venezuelan, shall be prepared from virus-bearing cell culture fluids. Only Master Seed which has been...

  9. 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. 113.308 Section 113.308 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE..., Venezuelan, shall be prepared from virus-bearing cell culture fluids. Only Master Seed which has been...

  10. 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. 113.308 Section 113.308 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE..., Venezuelan, shall be prepared from virus-bearing cell culture fluids. Only Master Seed which has been...

  11. Andes Mountains, Chile

    NASA Image and Video Library

    1994-09-30

    STS068-260-078 (30 September-11 October 1994) --- The ice visible along the bottom of this view is the north end of the larger (southern) of two great remaining ice field of the Andes Mountains in Chile. The longest glacier visible here flows down into the Calen Fjord (an arm of the Pacific Ocean known as Canal Baker) where numerous calved icebergs can be seen floating. The other three glaciers end in glacier-cut valleys with small lakes - the bigger lake has numerous icebergs as well. the river snaking through the mountains to the fjord drains water from the great Lake O'Higgins, which lies out of the picture to the right. Glacial mud can be seen emptying into the fjord and discoloring the water with its milky color.

  12. The phlebotomine sandflies of Venezuelan Amazonia.

    PubMed

    Feliciangeli, M D; Ramirez Perez, J; Ramirez, A

    1988-01-01

    Phlebotomine sandflies were surveyed in two ecologically contrasted areas, the northern moist and southern wet tropical forests, of the Territorio Federal Amazonas, Venezuela. Three new taxa and twenty-one new records were added to the previously known species list for Venezuelan sandflies, which now totals eighty species. Both sexes of Lutzomyia (Psychodopygus) killicki sp.n., L. (Trichophoryomyia) bettinii sp.n., L. (Nyssomyia) olmeca reducta subsp.n. and and the females of L. bernalei Osorno et al., Brumptomyia pintoi Costa Lima and L. begonae (Ortiz & Torres) are described and illustrated.

  13. External coating failures in Venezuelan pipelines

    SciTech Connect

    Rodriguez, V.; Paiva, A.; Castaneda, L.

    1994-12-31

    External organic coatings have been used in Venezuelan pipelines to prevent corrosion in different environments. These environments can be considered critical due to the high temperature of the fluid transported or due to the aggressiveness of the surrounding soils and waters. It has also been found that inadequate application of the coating has contributed greatly to a premature failure. An overview of the techniques used to determine the causes of the failures and the interpretation of the failure analysis will be presented in detail in this paper.

  14. 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.

  15. Bacteria recovered from a high-altitude, tropical glacier in Venezuelan Andes.

    PubMed

    Ball, María M; Gómez, Wileidy; Magallanes, Xavier; Rosales, Rita; Melfo, Alejandra; Yarzábal, Luis Andrés

    2014-03-01

    Glacial-ice microorganisms are intensively studied world-wide for a number of reasons, including their psychrophilic lifestyle, their usefulness in biotechnology procedures and their relationship with the search of life outside our planet. However, because of the difficulties for accessing and working at altitudes of >5.000 m above sea level, tropical glaciers have received much less attention than their arctic and antarctic counterparts. In the present work we isolated and characterized a total of forty-five pure isolates originating from direct plating of melted ice collected at the base of a rapidly-retreating, small glacier located at around 4.900 m.a.s.l. in Mount Humboldt (Sierra Nevada National Park, Mérida State, Venezuela). Initial examination of melted ice showed the presence of abundant- (>10⁶ cells ml⁻¹), morphologically diverse- and active bacterial cells, many of which were very small ("dwarf cells"). The majority of the isolates were psychrophilic or psychrotolerant and many produced and excreted cold-active extracellular enzymes (proteases and amylases). The antibiotic tests showed an elevated percentage of isolates resistant to high doses (100 μg/ml) of different antibiotics including ampicillin, penicillin, nalidixic acid, streptomycin, chloramphenicol, kanamycin and tetracycline. Multiresistance was also observed, with 22.22 % of the strains simultaneously resistant up to five of the antibiotics tested. Metal resistance against Ni⁺⁺, Zn⁺⁺ and Cu⁺⁺ was also detected. In accordance with these results, plasmids of low and high molecular weight were detected in 47 % of the isolates. Twenty-two partial 16S rDNA sequences analyzed allowed grouping the isolates within five different phyla/classes: Alpha-, Beta- and Gamma-proteobacteria, Actinobacteria and Flavobacteria. This is the first report concerning South American Andean glacial ice microorganisms.

  16. 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.

  17. Alphaviral equine encephalomyelitis (Eastern, Western and Venezuelan).

    PubMed

    Aréchiga-Ceballos, N; Aguilar-Setién, A

    2015-08-01

    Summary Alphaviral equine encephalomyelitis is a mosquito-borne infection that causes severe neurological disease and fatalities in horses and humans in the Americas. Consequently, the equine alphaviruses (Eastern, Western and Venezuelan) are of considerable concern worldwide and are notifiable to the World Organisation for Animal Health. In addition, these diseases are considered a potent potential biological weapon, emphasising the need to develop an effective vaccine. Alphaviral equine encephalomyelitis is caused by Eastern equine encephalomyelitis virus (EEEV), Western equine encephalomyelitis virus (WEEV) or Venezuelan equine encephalomyelitis virus (VEEV), which are related members of the Alphavirus genus in the Togaviridae family. Although related, the three viruses are genetically and antigenically distinct. The disease is characterised by fever, anorexia, depression and clinical signs of encephalomyelitis, and may be fatal in up to 90% of cases, for both humans and horses, particularly in the case of EEE. Surviving horses develop lifelong immunity but may have permanent neuropathology. The aim of this paper is to analyse the scientific information available on the evolution of EEE, WEE and VEE, and any potential vaccines.

  18. 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

    ... Complex (Complex), which includes Lake Andes NWR, Karl E. Mundt NWR, and Lake Andes Wetland Management... Andes Wetland Management District (WMD), and Karl E. Mundt NWR. The Complex lies within the Plains and... for waterfowl and other water birds. Lake Andes WMD was formed in the 1960s to protect wetland and...

  19. Genetic diversity of Venezuelan alphaviruses and circulation of a Venezuelan equine encephalitis virus subtype IAB strain during an interepizootic period.

    PubMed

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

    2015-07-01

    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.

  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. Venezuelan Equine Encephalitis Virus, Southern Mexico

    PubMed Central

    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.

    2004-01-01

    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

  2. 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…

  3. 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…

  4. Characterization of Venezuelan heavy oil vacuum residua

    SciTech Connect

    Izquierdo, A.; Carbognani, L.; Leon, V.; Parisi, A. )

    1988-06-01

    Characterization of abundant ''heavy'' feedstocks such as tar sands, heavy oils and vacuum residua will play a fundamental role in the use of these energy sources. Their physical and chemical properties vary from one feed to another, and this can have some consequences in their necessary upgrading processes. In this paper results on the characterization of 510/sup 0/C-vacuum residua (VR) obtained from Venezuelan Heavy and Medium Oils are presented. These are Morichal (Mo), Merey (Me), Guafita (Gu) and Barinas (Ba). The VR have all an API gravity between 3 and 6, more than 15% asphaltenes, metals above 200 ppm, as well as high contents of nitrogen, more than 6000 ppm, and sulphur, over 1%. It has been found that when these feeds are hydrotreated under similar conditions the processability improves in the order Ba

  5. 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.

  6. 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

  7. Occurrence of Proteus mirabilis associated with two species of venezuelan oysters.

    PubMed

    Fernández-Delgado, Milagro; Contreras, Monica; García-Amado, María Alexandra; Gueneau, Pulchérie; Suárez, Paula

    2007-01-01

    The fecal contamination of raw seafood by indicators and opportunistic pathogenic microorganisms represents a public health concern. The objective of this study was to investigate the presence of enteric bacteria colonizing oysters collected from a Venezuelan touristic area. Oyster samples were collected at the northwestern coast of Venezuela and local salinity, pH, temperature, and dissolved oxygen of seawater were recorded. Total and fecal coliforms were measured for the assessment of the microbiological quality of water and oysters, using the Multiple Tube Fermentation technique. Analyses were made using cultures and 16S rRNA gene sequencing. Diverse enrichment and selective culture methods were used to isolate enteric bacteria. We obtained pure cultures of Gram-negative straight rods with fimbriae from Isognomon alatus and Crassostrea rhizophorae. Our results show that P. mirabilis was predominant under our culture conditions. We confirmed the identity of the cultures by biochemical tests, 16S rRNA gene sequencing, and data analysis. Other enterobacteria such as Escherichia coli, Morganella morganii and Klebsiella pneumoniae were also isolated from seawater and oysters. The presence of pathogenic bacteria in oysters could have serious epidemiological implications and a potential human health risk associated with consumption of raw seafood.

  8. 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

  9. 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…

  10. [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.

  11. Transcultural diabetes nutrition algorithm (tDNA): Venezuelan application.

    PubMed

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

    2014-04-02

    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.

  12. Molecular systematics of the neotropical scorpion genus Tityus (Buthidae): the historical biogeography and venom antigenic diversity of toxic Venezuelan species.

    PubMed

    Borges, Adolfo; Bermingham, Eldredge; Herrera, Nimiadina; Alfonzo, Marcelo J; Sanjur, Oris I

    2010-01-01

    We provide a mitochondrial DNA-based phylogenetic hypothesis for 21 Tityus species collected in Venezuela, Trinidad, Brazil and Panama, including 12 taxa known to be toxic to humans. Our phylogenetic reconstruction is based on 850 nucleotides of the combined cytochrome oxidase subunit I and 16S rRNA genes for most species, and centered on Venezuelan scorpions owing to the detailed taxonomic and biogeographic information available for Tityus in this region. The principal phylogenetic result was the strong support for mtDNA clades representing geographical groupings associated with the Perijá mountain range, the Mérida Andes, or the central and eastern coastal ranges in Venezuela, suggesting that vicariance has been a potent force in the diversification of local scorpions. Venezuelan Tityus species have been organized by González-Sponga into three artificial morphological groups, "androcottoides", "discrepans", and "nematochirus", based on the array of ventral carinae in metasomal segments II-IV. We also incorporated a fourth morphological group ("Tityus clathratus"), recently documented in Venezuela. Our results do not support the clustering of the species in the "androcottoides" and "discrepans" morphological groups, which include the majority of taxa of medical importance, but provided support for the "nematochirus" species group. T. clathratus was found to cluster with the Brazilian T. serrulatus and T. bahiensis. Divergence times of most clades are consistent with major events in the geological history of northern Venezuela and suggest that many Venezuelan Tityus species formed in the late Miocene and the Pliocene. In turn, we used the Tityus mtDNA phylogeny to determine the potential utility of phylogenetic systematics to predict Tityus venom antigenic reactivity by testing the recognition of T. nororientalis, T. discrepans, T. zulianus, T. perijanensis, and T. clathratus venoms by anti-T. discrepans horse antibodies. Cross-reactivity was significantly

  13. 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.

  14. 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.

  15. Molecular Strategy for the Construction of a Genetically Engineered Vaccine for Venezuelan Equine Encephalitis Virus

    DTIC Science & Technology

    1991-03-29

    AD-A236 920 MOLECULAR STRATEGY FOR THE CONSTRUCTION OF A GENETICALLY ENGINEERED VACCINE FOR VENEZUELAN EQUINE ENCEPHALITIS VIRUS FINAL REPORT ROBERT...89-C-9089 engineered vaccine for Venezuelan Equine Encephalitis Virus 62787A 3M162787A871 AD Robert Edward Johnston WUDA318408 Nancy Lee Davis...multiple mutants were more attenuated than those containing a single attenuating Venezuelan equine encephalitis virus (VEE) full-length clones; In vitro

  16. Late Pleistocene glacial fluctuations in Cordillera Oriental, subtropical Andes

    NASA Astrophysics Data System (ADS)

    Martini, Mateo A.; Kaplan, Michael R.; Strelin, Jorge A.; Astini, Ricardo A.; Schaefer, Joerg M.; Caffee, Marc W.; Schwartz, Roseanne

    2017-09-01

    The behavior of subtropical glaciers during Middle to Late Pleistocene global glacial maxima and abrupt climate change events, specifically in Earth's most arid low-latitude regions, remains an outstanding problem in paleoclimatology. The present-day climate of Cordillera Oriental, in arid northwestern Argentina, is influenced by shifts in subtropical climate systems, including the South American Summer Monsoon. To understand better past glacier-subtropical climates during the global Last Glacial Maximum (LGM, 26.5-19 ka) and other time periods, we combined geomorphic features with forty-two precise 10Be ages on moraine boulders and reconstructed paleo-equilibrium line altitudes (ELA) at Nevado de Chañi (24°S) in the arid subtropical Andes. We found a major glacial expansion at ∼23 ± 1.6 ka, that is, during the global LGM. Additional glacial expansions are observed before the global LGM (at ∼52-39 ka), and after, at 15 ± 0.5 and 12 ± 0.6 ka. The ∼15 ka glacial event was found on both sides of Chañi and the ∼12 ka event is only recorded on the east side. Reconstructed ELAs of the former glaciers exhibit a rise from east to west that resembles the present subtropical climate trajectory from the Atlantic side of the continent; hence, we infer that this climate pattern must have been present in the past. Based on comparison with other low-latitude paleoclimate records, such as those from lakes and caves, we infer that both temperature and precipitation influenced past glacial occurrence in this sector of the arid Andes. Our findings also imply that abrupt deglacial climate events associated with the North Atlantic, specifically curtailed meridional overturning circulation and regional cooling, may have had attendant impacts on low subtropical Southern Hemisphere latitudes, including the climate systems that affect glacial activity around Nevado de Chañi.

  17. VIRUS-SPECIFIC POLYSOMES IN CELLS INFECTED WITH THE VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS,

    DTIC Science & Technology

    VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS, *RIBOSOMES, *TISSUE CULTURE CELLS, RIBOSOMES, GROWTH(PHYSIOLOGY), INFECTIOUS DISEASES, ARBOVIRUSES, VIRUSES, NUCLEIC ACIDS, BIOSYNTHESIS, USSR, MOLECULAR STRUCTURE.

  18. 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.

  19. 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.

  20. 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.

  1. Ubinas Volcano Activity in Peruvian Andes

    NASA Image and Video Library

    2014-05-01

    On April 28, 2014, NASA Terra spacecraft spotted signs of activity at Ubinas volcano in the Peruvian Andes. The appearance of a new lava dome in March 2014 and frequent ash emissions are signs of increasing activity at this volcano.

  2. 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 ...

  3. Gender differences in ancestral contribution and admixture in Venezuelan populations.

    PubMed

    Guerra, D Castro De; Pérez, C Figuera; Izaguirre, M H; Barahona, E Arroyo; Larralde, A Rodríguez; Lugo, M Vívenes De

    2011-06-01

    The origin of the contribution of uniparental heritage were analyzed in 615 samples of individuals proceeding from 13 towns classified according to historic differences in their emergence and development as African-derived, European-derived, and admixed/urban. Mitochondrial and Y-chromosome haplogroups were identified by PCR-restriction fragment length polymorphism. The results were compared with previous estimates of admixture made with autosomal markers and with historic aspects. The results show a predominantly indigenous genetic contribution through the female, being more prevalent in urban populations; the African contribution, although dispersed, presents a larger concentration in the African-derived towns, whereas the European contribution is limited to populations with this origin, reflecting isolation and the conservation of the distribution pattern of genes of the Colonial era. With regard to admixture through males, it is almost exclusively of European origin, whereas the African contribution is basically concentrated in the African-derived towns, and the Amerindian lineages are almost nonexistent. The genome of paternal heredity, as opposed to the autosomal and the mitochondrial, shows a homogeneous pattern of admixture that is independent of the origin of the population studied, suggesting that European genes have been introduced into the Venezuelan population through male immigrations, whereas the indigenous contribution has been preserved in the Venezuelan genetic pool through the women. These results provide evidence of the heterogeneity in the genetic origin of the Venezuelan population, which should be taken into account in forensic and epidemiologic genetic studies.

  4. Problem solving workshop for physics teachers at Venezuelan High School

    NASA Astrophysics Data System (ADS)

    Andrés, Maria Maite

    1997-03-01

    The Venezuelan Physics Olympiad is aimed at high school students. The syllabus at the high school level includes mechanics, electricity and magnetism, vibrations and waves, optics, fluid statics, and energy and its transformations. The Venezuelan Physics Olympiad consists of three tests. The preliminary test has 20 problems. They are multiple choice questions with a choice of five options. The theory test has 8 or 10 open-ended problems and the experimental final test is a problem whose solution it is made at the laboratory. The results of the five Venezuelan Physics Olympiads, 1991-1995, were analyzed. It was found that students solve physics problems the same way they solve mathematics exercises (1, 2). They emphasized the mathematical processes too much and paid little attention to description and analysis of the physical situation involved. Also, we observed that students did not develop experimental skills at school and their experience with laboratory work is very poor. According to these results, we designed two workshops for in-service physics teachers. One workshop focuses on solving pencil-and-paper-type problems, and the other one provides knowledge and skills about experimental work. Both workshops are designed with a cognitive approach (3-7).

  5. 1,5 iodonaphthyl Azide Inactivated V3526 Protects against Aerosol Challenge with Virulent Venezuelan Equine Encephalitis Virus.

    DTIC Science & Technology

    2016-06-02

    1 1,5 iodonaphthyl Azide-Inactivated V3526 Protects against Aerosol Challenge with Virulent Venezuelan Equine Encephalitis Virus . Paridhi...UNCLASSIFIED 2 Abstract: Venezuelan equine encephalitis virus (VEEV) is a New World alphavirus. There is no licensed vaccine for prophylaxis...Introduction: Venezuelan equine encephalitis virus (VEEV) vaccine development has been marred by failure of inactivated vaccines to develop efficient

  6. Venezuelan Bolivarian Missions in Colombia: What Are the Real, Underlying Reasons for Their Existence?

    DTIC Science & Technology

    2013-06-01

    Chávez; Colombia; Bolivarian Missions; Social Missions; Cuba; Bolivarianism; Missions Robinson; Milagro; Guacaipuro; Identidad; Socialism of the 21st...Century; Socialism ; Venezuelan Foreign Policy; Venezuelan-Cuban Relations; Chavismo; Insurgency; FARC; ELN; Political Interference; Ideological...Catatumbo (Peasant Association of the Catatumbo Region) BANDES Banco Nacional de Desarrollo Economico y Social (National Economic and Social

  7. An Analysis of the Structural Organization of the Venezuelan Naval Aviation.

    DTIC Science & Technology

    1987-12-01

    Venezuelan Navy, Organigrama Estructural, Febrero 1987. 15. Venezuelan Navy Manual de Fun amentos de Comando V Organizacion (MAN--ON--ESGN--00011...of Management Studies, Vol 13, May 1976. Lopez A. Organizacion Matricial en la UNET, Traba o de As~ TU1ive~i d"d-N1iZ!l- Ex er Imental del Tachira, San

  8. 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, Western, and Venezuelan, Killed Virus. 113.207 Section 113.207 Animals and Animal Products ANIMAL AND... Venezuelan, Killed Virus, shall be prepared from virus-bearing cell culture fluids. Each serial or subserial...

  9. 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, Western, and Venezuelan, Killed Virus. 113.207 Section 113.207 Animals and Animal Products ANIMAL AND... Venezuelan, Killed Virus, shall be prepared from virus-bearing cell culture fluids. Each serial or subserial...

  10. Dynamics, patterns and causes of fires in Northwestern Amazonia.

    PubMed

    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.

  11. 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

  12. 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.

  13. [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.

  14. Gas exchange and low temperature resistance in two tropical high mountain tree species from the Venezuelan Andes

    NASA Astrophysics Data System (ADS)

    Cavieres, Lohengrin A.; Rada, Fermín; Azócar, Aura; García-Núñez, Carlos; Cabrera, Hernán M.

    2000-05-01

    Temperature may determine altitudinal tree distribution in different ways: affecting survival through freezing temperatures or by a negative carbon balance produced by lower photosynthetic rates. We studied gas exchange and supercooling capacity in a timberline and a treeline species ( Podocarpus oleifolius and Espeletia neriifolia, respectively) in order to determine if their altitudinal limits are related to carbon balance, freezing temperature damage, or both. Leaf gas exchange, leaf temperature-net photosynthesis curves and leaf temperature at which ice formation occurred were measured at two sites along an altitudinal gradient. Mean CO 2 assimilation rates for E. neriifolia were 3.4 and 1.3 μmol·m -2·s -1, at 2 400 and 3 200 m, respectively. Mean night respiration was 2.2 and 0.9 μmol·m -2·s -1 for this species at 2 400 and 3 200 m, respectively. Mean assimilation rates for P. oleifolius were 3.8 and 2.2 μmol·m -2·s -1 at 2 550 and 3 200 m, respectively. Night respiration was 0.8 μmol·m -2·s -1 for both altitudes. E. neriifolia showed similar optimum temperatures for photosynthesis at both altitudes, while a decrease was observed in P. oleifolius.E. neriifolia and P. oleifolius presented supercooling capacities of -6.5 and -3.0 °C, respectively. For E. neriifolia, freezing resistance mechanisms are sufficient to reach higher altitudes; however, other environmental factors such as cloudiness may be affecting its carbon balance. P. oleifolius does not reach higher elevations because it does not have the freezing resistance mechanisms.

  15. 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

  16. Outbreak of vampire bat biting in a Venezuelan village.

    PubMed

    Caraballo, A J

    1996-10-01

    An outbreak of 154 cases of vampire bat biting in a four-month period in the gold mine of Payapal, a Venezuelan village, is reported. All patients were bitten during the night and the most bites were on their toes. No complication attributed to the bite was reported. Diagnoses of rabies virus made by means of immunofluorescence were negative. A possible reason for this outbreak may been the development of mining areas, with the inhabitants providing an alternative food source for the bats.

  17. [Frequency of Campylobacter pylori in apparently healthy and asymptomatic Venezuelans].

    PubMed

    Piñero, R; Urrestarazu, M; Serrano, N; González, R; Olavarría, R; Moncada, J; Khassale, M; Poleo, J R

    1989-01-01

    We evaluated 21 healthy asymptomatic Venezuelan volunteers free of risk factors for gastritis with upper gastrointestinal endoscopy, and four antral biopsies: a)2 for histological examinations, b) Urease test, c) culture and gram coloration. 13 out of 21 subjects were positive for Campylobacter pylori (61.30%) all of them had chronic gastritis and in the negative cases 7 were considered histologically normal. Urease test was positive in 12/13 with a sensitivity of 92% and 100% specificity. Frequency in our series is high for Campylobacter pylori (61.30%) and this justify prospective and massive study of the population to detect de prevalence in our country with simpler and cheaper methods.

  18. Experimental Venezuelan Equine Encephalomyelitis Virus Infection of the Bovine

    PubMed Central

    Walton, Thomas E.; Johnson, Karl M.

    1972-01-01

    Two groups of four dairy cows (Bos taurus) were infected subcutaneously with the epizootic Venezuelan equine encephalomyelitis virus (VEE) strains MF-8 and San Pelayo, respectively. Animals experienced no clinical illness, but all developed significant neutropenia. Virus was recovered once each from the blood of three animals but did not exceed 102.2 SMICLD50 (Suckling mouse intracerebral lethal dose50)/ml. Specific neutralizing antibodies appeared in the serum of all animals, but there were no significant differences in titers against different naturally occurring VEE subtypes. Dairy cattle thus appear to play no role in virus transmission during VEE epizootics but may serve as retrospective immunological sentinels of virus activity. PMID:4564396

  19. ANDES: An Underground Laboratory in South America

    NASA Astrophysics Data System (ADS)

    Dib, Claudio O.

    ANDES (Agua Negra Deep Experiment Site) is an underground laboratory, proposed to be built inside the Agua Negra road tunnel that will connect Chile (IV Region) with Argentina (San Juan Province) under the Andes Mountains. The Laboratory will be 1750 meters under the rock, becoming the 3rd deepest underground laboratory of this kind in the world, and the first in the Southern Hemisphere. ANDES will be an international Laboratory, managed by a Latin American consortium. The laboratory will host experiments in Particle and Astroparticle Physics, such as Neutrino and Dark Matter searches, Seismology, Geology, Geophysics and Biology. It will also be used for the development of low background instrumentation and related services. Here we present the general features of the proposed laboratory, the current status of the proposal and some of its opportunities for science.

  20. Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies

    NASA Astrophysics Data System (ADS)

    Hernandez, Orlando

    Northwestern South America is one of the most populated regions of the Americas with more than 80 million people concentrated along the Andes Mountains. This region includes a complex and dangerous mosaic of tectonic plates that have produced devastating earthquakes, tsunamis, volcanic eruptions and landslides in the last decades. The region's economic development has also seriously suffered because the region is poorly explored for natural resources. To more effectively assess the tectonic hazards and mineral and energy resources of this region, we must improve our understanding of the tectonic setting that produced them. This research develops improved tectonic models for northwestern South America from available satellite, airborne and surface gravity and magnetic data integrated with global digital topography, seismic, and GPS plate velocity data. Reliable crustal thickness estimates that help constrain tectonic stress/strain conditions were obtained by inverse modeling of the magnetic anomalies and terrain compensated gravity anomalies. Correlated positive Terrain Gravity Effects (TGE) and Free Air Gravity Anomalies (FAGA) suggest that the crust - mantle interface under the northwestern Andes is closer to the surface than expected, indicating that these mountains are not iso-statically compensated. Correlated negative FAGA anomalies observed along western South America and the Greater and Lesser Antilles islands are associated with iso-statically disturbed mantle displaced by subducting oceanic plates. Subtracting TGE from the terrain-correlated FAGA (TCFAGA) yield compensated terrain gravity effect (CTGE) anomalies that characterize the Andes Mountains with deep roots of low density crust displacing denser underlying mantle and thickening the local crust. FAGA and TGE correlate at all levels of compensation, but the correlations are especially strong where the compensation is less than 100%. Correlated first vertical derivative FAGA (FVD(FAGA)) and

  1. 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.

  2. Characterising the Venezuelan Troposphere for Radio-Astronomy Studies

    NASA Astrophysics Data System (ADS)

    Pacheco, R.; Muñoz, A. G.; Brito, A.; Cubillán, N.

    2009-05-01

    Venezuela possesses a very useful geographical location for doing Radioastronomy. Recently, the Venezuelan Government (via FIDETEL-Ministerio de Ciencia y Tecnología) has aproved to the Laboratorio de Astronomía y Física Teórica (LAFT) of La Universidad del Zulia (Venezuela) the adquisition of four 3 meter diameter parabolic dishes that will be set as a radio-interferometer receiver and that can be used for certain Radioastronomy purposes. The specifications of the instrument will be treated elsewhere (Muñoz and Hernández 2007). To this aim, as ussually, the first step is to characterize the losses due to the atmosphere, and their evolution over time. In previous works (Muñoz et al. 2004, Memoires of V RIAO/VIII OPTILAS, M10-5 Modelling Tropospheric Radio-Attenuation Parameters for Venezuela, 359; Muñoz et al. 2006, CIENCIA, Vol. 14, 4, 428) we have studied some relevant electromagnetic (e-m) attenuation parameters dueto hydrometeors and absortion gases in the lower atmosphere, focused in local telecommunication applications (surface e-m trajectories). In this work we extend our results to include the cenital and quasi-cenital e-m trajectories, characterizing thus the medium losses in the 0.4-4.0 GHz spectral window for several Venezuelan locations. We report refractivity values and their gradients, tropospheric indexes, extinction coefficients and the total rain attenuation for the whole territory under study.

  3. 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.

  4. [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.

  5. Earth - False Color Mosaic of the Andes

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This false-color mosaic of the central part of the Andes mountains of South America (70 degrees west longitude, 19 degrees south latitude) is made up of 42 images acquired by the Galileo spacecraft from an altitude of about 25,000 kilometers (15,000 miles). A combination of visible (green) and near-infrared (0.76 and 1.0-micron) filters was chosen for this view to separate regions with distinct vegetation and soil types. The mosaic shows the area where Chile, Peru and Bolivia meet. The Pacific Coast appears at the left of the image-- Galileo captured this view as it traveled west over the Pacific Ocean, looking back at the Andes. Lakes Titicaca and Poopo are nearly black patches at the top and center, respectively; a large light-blue area below and to the left of Lake Poopo is Salar de Uyuni, a dry salt lake some 120 kilometers (75 miles) across. These lakes lie in the Altiplano, a region between the western and eastern Andes, which are covered by clouds. The vegetation-bearing Gran Chaco plains east of the Andes appear pale green. Light-blue patches in the mountains to the north are glaciers.

  6. ANDES TOOLS: Promotional slides for Industrial Clients

    DTIC Science & Technology

    2015-09-03

    Briefing Charts 3. DATES COVERED (From - To) 10 August 2015 – 3 September 2015 4. TITLE AND SUBTITLE ANDES TOOLS: Promotional slides for Industrial...Industrial Clients PA Case Number: #15479; Clearance Date: 9/3/2015 14. ABSTRACT Briefing Charts/Viewgraphs 15. SUBJECT TERMS N/A 16. SECURITY

  7. Eastern Iowa, Northwestern Illinois

    NASA Image and Video Library

    1973-06-22

    SL2-10-250 (May-June 1973) --- A vertical view of eastern Iowa and northwestern Illinois, as photographed from Skylab space station in Earth orbit. Davenport, Burlington and Muscatine, Iowa; and Rock Island and Moline, Illinois can be delineated on opposite sides of the Mississippi River. The Iowa River and tributaries of it can also be delineated. This photograph was taken with one of six lenses of the Itek-furnished Multispectral Photographic Facility Experiment S190-A mounted in the Multiple Docking Adapter (MDA) of the space station. A six-inch lens, using 70mm medium speed Ektachrome (SO-356) film, was used. Agencies participating with NASA on the EREP project are the Departments of Agriculture, Commerce and Interior; the Environmental Protection Agency and the Corps of Engineers. All EREP photography is available to the public through the Department of Interior's Earth Resources Observations Systems Data Center, Sioux Falls, South Dakota, 57198. Photo credit: NASA

  8. 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.

  9. 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

  10. Postepizootic Persistence of Venezuelan Equine Encephalitis Virus, Venezuela

    PubMed Central

    Navarro, Juan-Carlos; Medina, Gladys; Vasquez, Clovis; Coffey, Lark L.; Wang, Eryu; Suárez, Alexander; Biord, Hernán; Salas, Marlene

    2005-01-01

    Five years after the apparent end of the major 1995 Venezuelan equine encephalitis (VEE) epizootic/epidemic, focal outbreaks of equine encephalitis occurred in Carabobo and Barinas States of western Venezuela. Virus isolates from horses in each location were nearly identical in sequence to 1995 isolates, which suggests natural persistence of subtype IC VEE virus (VEEV) strains in a genetically stable mode. Serologic evidence indicated that additional outbreaks occurred in Barinas State in 2003. Field studies identified known Culex (Melanoconion) spp. vectors and reservoir hosts of enzootic VEEV but a dearth of typical epidemic vectors. Cattle serosurveys indicated the recent circulation of enzootic VEEV strains, and possibly of epizootic strains. Persistence of VEEV subtype IC strains and infection of horses at the end of the rainy season suggest the possibility of an alternative, cryptic transmission cycle involving survival through the dry season of infected vectors or persistently infected vertebrates. PMID:16485478

  11. 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.

  12. 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.

  13. 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.

  14. Andes: An Intelligent Homework System for Introductory Physics

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    We know that students benefit from solving homework problems under the guidance of an expert (human) tutor. The Andes system (http://www.andes.pitt.edu) is designed for students to solve homework problems under the guidance of an expert computer tutor. Andes encourages students to use sound problem solving techniques and provides immediate right/wrong feedback on each step of a solution. On request, Andes also provides hints based on previous student actions. I will discuss how Andes works, from a student's perspective, and summarize research that demonstrates its effectiveness as a pedagogical tool. I will also discuss how Andes can function as a tool for conducting educational research, presenting an investigation of students' hint usage as an example.

  15. 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.

  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. 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.

  18. Caravan-submm, A Fisrt Black Hole Imager at Andes

    NASA Astrophysics Data System (ADS)

    Miyoshi, M.; Kasuga, T.; Ishitsuka Iba, J. K.; Oka, T.; Sekido, M.; Takefuji, K.; Takahashi, M.; Saida, H.; Takahashi, R.

    2017-07-01

    We introduce our Peruvian-Japanese black hole imaging project, Caravan-submm at Andes. By constructing a sub-millimeter wavelength (submm) VLBI network at Andes we aim to get images of black hole horizon and the surroundings of Sgr A*. The array contains at least two fixed VLBI stations and one mobile VLBI station.

  19. A Northern Hemisphere perspective on Holocene hydroclimate trends in the tropical Andes

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    Reconstructions of tropical precipitation are important for determining the sensitivity of rainfall patterns in the tropics to climate variability and improving the accuracy of projected hydrologic changes in a warming world. In tropical South America, precipitation is dominantly controlled by the South American Monsoon system (SAM), which operates in conjunction with the position of the Intertropical Convergence Zone (ITCZ) and the El Niño Southern Oscillation (ENSO) to deliver water resources to hundreds of millions of people. The classic model of South American hydroclimate evolution during the Holocene (past 11 ka) invokes an anti-phased pattern of precipitation between hemispheres, whereby orbital forcing drove a gradual displacement of the ITCZ, causing a southerly shift in seasonal convection and precipitation, and strengthening the SAM as Southern Hemisphere summer insolation increased. Indeed, paleoclimate records derived from multiple geologic archives support this pattern. However, the vast majority of existing records come from the southern tropics and emerging terrestrial datasets from the northern tropics appear contrary to the paradigm. Here, we present lake sediment evidence for coupled hydroclimate and environmental changes from the Venezuelan Andes, a key region for investigating interhemispheric linkages and drivers of tropical hydroclimate variability. Compound specific hydrogen isotope ratios from terrestrial plant waxes and algal lipids, together with supporting sedimentary indicators of runoff and aridity, provide a comprehensive reconstruction of Northern Hemisphere tropical precipitation at local and regional scales. Our results are consistent in sign and magnitude to precipitation reconstructions from both hemispheres, indicating interhemispheric similarities in tropical hydroclimate variability and calling into question the synchronicity and phasing of hydroclimate trends in South America.

  20. 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.

  1. 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.

  2. Characterization of genetic variability of Venezuelan equine encephalitis viruses

    DOE PAGES

    Gardner, Shea N.; McLoughlin, Kevin; Be, Nicholas A.; ...

    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

  3. Characterization of genetic variability of Venezuelan equine encephalitis viruses

    SciTech Connect

    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 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. Lastly, we identified genomic variants associated with serotypes and host species, revealing a complex relationship between genotype and phenotype.

  4. 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.

  5. Venezuelan Equine Encephalitis Virus Capsid-The Clever Caper.

    PubMed

    Lundberg, Lindsay; Carey, Brian; Kehn-Hall, Kylene

    2017-09-29

    Venezuelan equine encephalitis virus (VEEV) is a New World alphavirus that is vectored by mosquitos and cycled in rodents. It can cause disease in equines and humans characterized by a febrile illness that may progress into encephalitis. Like the capsid protein of other viruses, VEEV capsid is an abundant structural protein that binds to the viral RNA and interacts with the membrane-bound glycoproteins. It also has protease activity, allowing cleavage of itself from the growing structural polypeptide during translation. However, VEEV capsid protein has additional nonstructural roles within the host cell functioning as the primary virulence factor for VEEV. VEEV capsid inhibits host transcription and blocks nuclear import in mammalian cells, at least partially due to its complexing with the host CRM1 and importin α/β1 nuclear transport proteins. VEEV capsid also shuttles between the nucleus and cytoplasm and is susceptible to inhibitors of nuclear trafficking, making it a promising antiviral target. Herein, the role of VEEV capsid in viral replication and pathogenesis will be discussed including a comparison to proteins of other alphaviruses.

  6. Venezuelan equine encephalitis virus infection of spiny rats.

    PubMed

    Carrara, Anne-Sophie; Gonzales, Gonzales; Ferro, Cristina; Tamayo, Margarita; Aronson, Judith; Paessler, Slobodan; Anishchenko, Michael; Boshell, Jorge; Weaver, Scott C

    2005-05-01

    Enzootic strains of Venezuelan equine encephalitis virus (VEEV) circulate in forested habitats of Mexico, Central, and South America, and spiny rats (Proechimys spp.) are believed to be the principal reservoir hosts in several foci. To better understand the host-pathogen interactions and resistance to disease characteristic of many reservoir hosts, we performed experimental infections of F1 progeny from Proechimys chrysaeolus collected at a Colombian enzootic VEEV focus using sympatric and allopatric virus strains. All animals became viremic with a mean peak titer of 3.3 log10 PFU/mL, and all seroconverted with antibody titers from 1:20 to 1:640, which persisted up to 15 months. No signs of disease were observed, including after intracerebral injections. The lack of detectable disease and limited histopathologic lesions in these animals contrast dramatically with the severe disease and histopathologic findings observed in other laboratory rodents and humans, and support their role as reservoir hosts with a long-term coevolutionary relationship to VEEV.

  7. Assessment of routine malaria diagnosis in the Venezuelan Amazon.

    PubMed

    Metzger, W G; Vivas-Martínez, S; Giron, A; Vaccari, E; Campos, E; Rodríguez, I; Miranda, E; Terán, E; Olivo, L; Magris, M

    2011-05-01

    The quality of routine malaria diagnosis is a crucial topic of malaria control. The aim of this assessment was to monitor and evaluate the quality of routine malaria diagnosis in Amazonas (Venezuela) and to improve the quality control system. The traditional non-blinded quality control system was found to be overburdened with diagnostic samples. A modified sampling system with fewer samples to be tested was proposed. Expert microscopists blindly double-checked 1000 slides and 550 rapid diagnostic tests (RDT) (OptiMAL-IT) from health posts (HP). For Plasmodium vivax, HP microscopy and OptiMAL-IT showed sensitivies of 86% and 63%, respectively. For P. falciparum, HP microscopy and OptiMAL-IT showed sensitivities of 68% and 89%, respectively. Both methods lost accuracy when fewer parasites occurred in the sample. HP microscopists from different municipalities displayed significant differences in diagnostic quality. Overall, quality of routine malaria diagnosis in the Venezuelan Amazon is good but not optimal. The change from the traditional non-blinded quality control system to blinded cross-checking of a minimal selection of samples is - comparatively - a low cost intervention with possibly high impact on the quality of routine malaria diagnosis. The introduction of RDTs should be discussed carefully in order not to displace an existing network of HP microscopists. Copyright © 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

  8. [Anthropometric characteristics and skeletal maturity of male Venezuelan swimmers].

    PubMed

    Salazar-Lioggiodice, Marinés; Arroyo, Esteban; Pérez, Betty

    2006-06-01

    Knowledge of the morph-physiological conditions of young athletes, it of the utmost importance for planning better trainning programs and to identify those characteristics that lead to a better performance. This paper aims to classify a group of 114 male Venezuelan swimmers of the Miranda State contingent, aged between 7.00 and 18.99 years old, based on their anthropometric characteristics and skeletal maturity. For this purpose multivariate methods: Analysis of Principal Components (APC) and the Automatic Classification were employed. Anthropometric variables followed the International Society for the Advancement of Kinantropometry (ISAK) guidelines. Skeletal maturity and five indexes of body composition: brachial, crural, cormic and acromiale-iliac indexes, were additionally considered in the analysis. Three groups emerged very well defined and homogenous within and between groups. The first group identifies the younger swimmers with the smallest values in corporal dimensions. The second group comprises those swimmers characterized fundamentally by a greater development of the bicrestal diameter. In the third group, greater values of the anthropometrical variables were found, that shaped the typical profile of the swimmers, mainly characterized by a trapezoidal trunk. Most of the swimmers are advanced in skeletal age related to chronological age. This clustering of the swimmers permits a suitable way to identify the bio-morphological characteristics of the athletes.

  9. 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.

  10. [Pneumocystosis in Venezuelan patients: epidemiology and diagnosis (2001-2006)].

    PubMed

    Panizo, María Mercedes; Reviákina, Vera; Navas, Trina; Casanova, Karina; Sáez, Alejandro; Guevara, Rafael Napoleón; Cáceres, Ana María; Vera, Raúl; Sucre, Carlos; Arbona, Esther

    2008-12-31

    The objective of this work was to investigate the epidemiology of pneumocystosis in Venezuelan patients utilizing a retrospective study during a six year period. One hundred and twenty nine clinical samples collected from patients with AIDS, cancer and non-AIDS-non-cancer low respiratory tract infection patients were processed by direct immunofluorescence technique. Pneumocystosis was diagnosed in 30 patients with a general frequency of 23.3%, which varied according to the patient's group: 36.6% in AIDS patients, 38% in cancer patients, and 10.4% in non-AIDS-non-cancer low respiratory tract infection patients. This study demonstrated the existence of differences in pneumocystosis frequency related to the patient's underlying disease, and that the illness is an important health problem in immunocompromised patients in Venezuela. Pneumocystosis must be suspected in non-immunocompromised patients with signs and symptoms of low respiratory tract infection, and the study of this illness must include COPD and cancer patients. Direct immunofluorescence is a useful technique for pneumocystosis diagnosis, however, it requires an optimal sample and skilled personnel in the laboratory.

  11. Sandstone caves on Venezuelan tepuis: Return to pseudokarst?

    NASA Astrophysics Data System (ADS)

    Aubrecht, R.; Lánczos, T.; Gregor, M.; Schlögl, J.; Šmída, B.; Liščák, P.; Brewer-Carías, Ch.; Vlček, L.

    2011-09-01

    Venezuelan table mountains (tepuis) host the largest arenite caves in the world. The most frequently used explanation of their origin so far was the "arenization" theory, involving dissolution of quartz cement around the sand grains and subsequent removing of the released grains by water. New research in the two largest arenite cave systems - Churi-Tepui System in Chimanta Massif and Ojos de Cristal System in Roraima Tepui showed that quartz dissolution plays only a minor role in their speleogenesis. Arenites forming the tepuis are not only quartzites but they display a wide range of lithification and breakdown, including also loose sands and sandstones. Speleogenetic processes are mostly concentrated on the beds of unlithified sands which escaped from diagenesis by being sealed by the surrounding perfectly lithified quartzites. Only the so-called "finger-flow" pillars testify to confined diagenetic fluids which flowed in narrow channels, leaving the surrounding arenite uncemented. Another factor which influenced the cave-forming processes by about 30% was lateritization. It affects beds formed of arkosic sandstones and greywackes which show strong dissolution of micas, feldspars and clay minerals, turning then to laterite ("Barro Rojo"). The main prerequisite to rank caves among karst phenomena is dissolution. As the dissolution of silicate minerals other than quartz appears to play not only a volumetrically important role but even a trigger role, these arenitic caves may be ranked as karst.

  12. Killing tanoak in northwestern California

    Treesearch

    D. F. Roy

    1956-01-01

    Residual tanoak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.) trees and tanoak sprouts often are an important component of the vegetation which competes with conifer reproduction in northwestern California. Sometimes enough tanoak is present in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands to dominate the...

  13. Temporal distribution of heavy metal concentrations in oysters Crassostrea rhizophorae from the central Venezuelan coast.

    PubMed

    Alfonso, Juan A; Handt, Helga; Mora, Abrahan; Vásquez, Yaneth; Azocar, José; Marcano, Eunice

    2013-08-15

    The oyster Crassostrea rhizophorae is a bivalve abundant in Venezuelan estuaries and consumed by local populations. No known values have been reported on trace metals in oysters from the central Venezuelan coast. We report the concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn in the soft parts of C. rhizophorae, which were collected bimonthly between March 2008 and March 2009, at two sampling areas from the Central Venezuelan Coast: Buche estuary and Mochima estuary. Our results show that for each metal there is a similar temporal variation pattern. The concentrations of the heavy metals reported in this work are useful as reliable baselines and can be used for comparison in future environment studies. Concentrations in C. rhizophorae from the Buche estuary can be interpreted to be high on a global scale for Cd, Cu, Ni and Mn, indicating atypically raised bioavailabilities.

  14. 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

  15. [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.

  16. 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.

  17. The Southern Andes Between 36o and 40o S Latitude: Seismicity and Average Velocities

    NASA Astrophysics Data System (ADS)

    Bohm, M.; Bruhn, C.; Asch, G.; Bataille, K.; Rietbrock, A.; ISSA Working Group,; ISSA Working Group,; ISSA Working Group,; ISSA Working Group,; ISSA Working Group,

    2001-12-01

    A temporary seismological network was installed as part of the project ISSA 2000 (Integrated Seismological experiment in the Southern Andes) between 36o and 40o S above the active continental margin in the Southern Andes reaching from the Chilean Pacific coast to 68o W in Argentina. The network consisted of 62 seismographs recording continuously from November 1999 to April 2000. We recorded on average 3 to 4 local earthquakes per day, mainly concentrated in the northwestern part of the network, resulting in a data set of 300 seismic events. High quality P and S arrival times of 120 earthquakes were inverted simultanously for 1-D velocity structure and hypocentral coordinates. Precise hypocenter locations of local earthquakes are determinted resulting in the first accurate image of the Wadati-Benioff zone south of Concepcion. The 1-D velocity model serves as initial reference model of seismic velocity tomographic studies, preliminary results of which will be presented. A further research interest of this seismological experiment is the determination of source mechanisms. Moment tensor inversions provide important information on the current stress field. It is postulated by several authors that dehydration processes are the cause of intermediate depth earthquakes while the focal mechanisms in the seismic coupling zone will be controlled by the deformation processes of the continental crust. A distinct non double couple part of the moment tensor will be expected in the zones of dehydration processes. The recorded data base allows a detailed investigation of local events in a higher frequency range. Instead of using the seismograms directly, the inversion for the moment tensor can also be performed on amplitude spectra. This method has the advantage that slight misalignments between seismograms and Greens functions do not bias the outcome, because the phase spectrum is not used at all.

  18. 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.

  19. SRTM Anaglyph: Laguna Mellquina, Andes Mountains, Argentina

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This anaglyph of an area south of San Martin de Los Andes, Argentina, is the first Shuttle Radar Topography Mission (SRTM) view of the Andes Mountains, the tallest mountain chain in the western hemisphere. This particular site does not include the higher Andes peaks, but it does include steep-sided valleys and other distinctive landforms carved by Pleistocene glaciers. Elevations here range from about 700 to 2,440 meters (2,300 to 8,000 feet). This region is very active tectonically and volcanically, and the landforms provide a record of the changes that have occurred over many thousands of years. Large lakes fill the broad mountain valleys, and the spectacular scenery here makes this area a popular resort destination for Argentinians.

    This anaglyph was produced by first shading a preliminary SRTM elevation model. The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission aboard Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed

  20. Neuro-Immune Mechanisms in Response to Venezuelan Equine Encephalitis Virus Infection

    DTIC Science & Technology

    2000-01-01

    Human T-Cell Lymphotropic Virus Type 1 125 (HTLV- 1 ) Tax: Induction of Tumor Necrosis Factor Alpha and...1987), Visna virus (Stowring et al., 1985), Borna virus (Carbone et al., 1991), as well as Human Immunodeficiency virus type- 1 (Tornatore et al., 1994...nick end labeling VEE Venezuelan equine encephalitis virus VSV Vesicular stomatitis virus WEE Western equine encephalitis virus 1 CHAPTER 1

  1. Role of Cytokines and Neurotrophins in the Central Nervous System in Venezuelan Equine Encephalitis Pathogenesis

    DTIC Science & Technology

    2001-03-21

    to, Crohn s disease (63), atherosclerotic plaques (47), autoimmune encephalomyelitis (96), Japanese encephalitis (132), and Venezuelan equine...astrocytes.................................................58 xi LIST OF ABBREVIATIONS AD Alzheimer s Disease AIDS Acquired Immune Deficiency Syndrome...line derived neurotrophic factor HAM HTLV-Associated Myelopathy HD Huntington s Disease HIV Human Immunodeficiency Virus HTLV Human T-Lymphotrophic

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

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., Western, and Venezuelan, Killed Virus. 113.207 Section 113.207 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis...

  3. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., Western, and Venezuelan, Killed Virus. 113.207 Section 113.207 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis...

  4. 9 CFR 113.207 - Encephalomyelitis Vaccine, Eastern, Western, and Venezuelan, Killed Virus.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., Western, and Venezuelan, Killed Virus. 113.207 Section 113.207 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS Killed Virus Vaccines § 113.207 Encephalomyelitis...

  5. Venezuelan 'Demonstradora Del Hogar': An Example of Women in Nonformal Rural Education

    ERIC Educational Resources Information Center

    Ruddle, Kenneth; Chesterfield, Ray

    1974-01-01

    An exception to Latin American extension program's stereotyped image of women is the Venezuelan home demonstrator program. A woman spends three years in trainning to enable her to effectively train village housewives in culturally acceptable ways to participate in the commercial sector of a modern farming economy. (AG)

  6. Aracar Volcano, Andes Mountains, Argentina near Chile Border

    NASA Image and Video Library

    2008-09-04

    The Andes Mountains, part of the Southern Cordillera formed from subduction zone volcanism at the convergent boundary of the Nazca plate and the South American plate. This image is from NASA EarthKAM.

  7. The Glaciation of the Ecuadorian Andes

    NASA Astrophysics Data System (ADS)

    Schubert, Carlos

    This pleasing book fills the gap in the knowledge about Pleistocene and recent glaciation between Colombia and Peru. A significant amount of data exists already for Colombia and Venezuela and for Peru, Bolivia, and, particularly, Chile. Hastenrath has now given us a description of glaciers and glaciation underneath the equator in the Andes.The book begins with brief summaries of the physiography and the atmospheric circulation, which give the general setting of Ecuador. Then follow detailed descriptions of the glaciers and glacial morphology of all the important mountains of the Western and Eastern Cordilleras. These are well illustrated, and a particularly useful feature is the comparison of old photographs and paintings of glaciers with modern photographs, many taken by the author. All illustrate the spectacular retreat of the glaciers in the Ecuadorian Andes during the last century and correlate quite well with observations elsewhere. This retreat is snown quantitatively in Table 4, in terms of decrease in glacier-covered area since the glacial advance of moraine stage III. The area of present-day glaciers is about 10% of the area during that stage (compared with about 1.5% in the Sierra Nevada de Mérida, Venezuela). A series of maps show the glacial morphology of the mountains (unfortunately, some of the maps have been included within the binding, thus losing some information; they could have been reduced somewhat to fit a single page or, if too large, could have been included in the pocket, together with the map of Chimborazo-Carihuairazo).

  8. [Lipid profile in Venezuelan preschoolers by socioeconomic status].

    PubMed

    Velásquez, Emma; Adela Barón, María; Solano, Liseti; Páez, Maria; Llovera, Daisy; Portillo, Zulay

    2006-03-01

    Epidemiological studies have shown that unfavorable serum lipids levels in childhood are predictors of development of atherosclerosis lesions in adulthood. We assessed the lipid profile of 297 Venezuelan preschool children (4-7 years old) from two socioeconomic levels in order to compare them by this characteristic. Their social level was determined according to modified Graffar method, and two groups were obtained: high socioeconomic status (HSES, n=103) and low socioeconomic status (LSES, n=194). Nutritional anthropometric evaluation was performed by weight to height, and NCHS/OMS cut-off point was used. Lipid profile was determined by colorimetric biochemical methods and atherogenic risks factors were calculated. Underweight for HSES was 5.8% and for LSES: 14.9%, while normal status was 78.6% and 70.1%, and overweight was 15.5% and 14.9%, respectively. Mean values for triglycerides were 0.66 +/- 0.27and 0.76 +/- 0.31 mmol/L, total cholesterol (TC): 3.61 +/- 0.65 and 2.98 +/- 0.71 mmol/L, HDL-C: 1.04 +/- 0.18 and 0.62 +/- 0.16 mmol/L, LDL-C: 2.27 +/- 0.61 and 2.01 +/- 0.71 mmol/L, TC/HDL-C: 3.5 +/- 0.78 and 5.0 +/- 1.5; LDL-C/HDL-C: 2.0 +/- 0.71 and 3.4 +/- 1.4 with significant differences between HSES and LSES as shown respectively. A significant association was found (p < 0.01) between lipid values and socioeconomic status, being the LSES preschoolers those with the higher atherogenic risk. Its pattern was of lower HDL-C levels, and higher TC/HDL-C and LDL-C/HDL-C ratio. Comparisons of lipid profile by nutritional status or gender did not show significant differences. Findings indicate that children from low socioeconomic status are at a higher risk for cardiovascular disease and atherosclerosis than children from high socioeconomic status.

  9. Oral and oropharyngeal cancer in a Venezuelan population.

    PubMed

    Rivera, Helen; Nikitakis, Nikolaos G; Correnti, María; Maissi, Sara; Ponce, José G

    2008-01-01

    The aim of this work was to analyze diagnosed cases of Oral Cancer (OC) and Oropharyngeal Cancer (OPC) in a Venezuelan population. We clinically evaluated 130 patients with OC and OPC and a histopathologic diagnosis of squamous cell carcinoma. The patients were analyzed according to gender age, and use of alcohol and tobacco and the tumors were classIfied based on anatomic location, staging parameters, and degree of difFerentiation. Ninety one patients (70%) were male and 39 (30%) were female. Patients' age ranged from 26 to 86 years old. Use of smoking tobacco, alcohol or both was reported by 84.3%, 49.1% and 45.4% of patients, respectively, and was more frequent in males. The most common oropharyngeal anatomic location was the base of the tongue (22.3%), followed by the tonsils (13.9%), while the most frequently affected oral location was the oral tongue (19.2%) followed by the gingiva and alveolar mucosa (10.8%), and the floor of mouth (7.7%). The majority of tumors (77.7%) were diagnosed at an advanced stage (Stage III or IV); metastasis to the regional lymph nodes occurred in 53.1% of cases. According to degree of diferentiation, well, moderately and poorly difFerentiated tumors accounted for 45.4%, 46.1% and 8.5% of cases, respectively. Well differentiated tumors accounted for 56.7% of OC cases, while the majority of OPC cases were classified as moderately or poorly differentiated (72.3%) (p < or = 0.002). Also, non-metastatic cases (NO) showed a predominance of well-diferentiated tumors (61.2%), while metastatic tumors (N+) were classified as moderately or poorly differentiated in 89.8% of cases (p < or = 0.0001). Our study population was characterized by a predominance of smokers and/or drinkers and a predilection for male patients. Most tumors were diagnosed at an advanced stage with a high incidence of metastatic spread to the regional lymph nodes, indicating possible delays in diagnosis. Less differentiated tumors were more frequently encountered among

  10. Angiosperm flora on the páramos of northwestern Colombia: diversity and affinities.

    PubMed

    Alzate-Guarín, Fernando; Murillo-Serna, Jhon Steven

    2016-01-01

    Páramos are high-elevation isolated ecosystems in the Andes characterized by specific flora. This flora includes a number of endemic species and some taxa phylogenetically related to temperate lineages (van der Hammen and Cleef 1986). There are six páramo units or complexes in the Department of Antioquia, located in northwestern Colombia. For five years, we conducted botanic explorations in order to quantify the richness of angiosperm flora in these units. We estimate the richness of angiosperms in these páramos at 693 species, 277 genera, and 86 families, which represent almost 10% of the floral diversity in Antioquia, but contained in only 0.7% of its area. We found that Frontino-Urrao is the most species-rich páramo with 465 species from 225 genera. Our results show that the most diverse angiosperm families of the páramos of Antioquia are Asteraceae, Orchidaceae, Melastomataceae, and Poaceae, which together represent 245 species. Groupings between páramos by Sørensen's similarity index show that the complexes of the Central Andes Cordillera form a cluster of greater affinity than Páramos from other regions. Of the species found, 80 have a CITES or IUCN diagnosis. The expeditions allowed the identification of 21 species not previously registered in Antioquia and a considerable number of endemisms (35 species), further proof of the high plant diversity in these ecosystems.

  11. 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

  12. Angiosperm flora on the páramos of northwestern Colombia: diversity and affinities

    PubMed Central

    Alzate-Guarín, Fernando; Murillo-Serna, Jhon Steven

    2016-01-01

    Abstract Páramos are high-elevation isolated ecosystems in the Andes characterized by specific flora. This flora includes a number of endemic species and some taxa phylogenetically related to temperate lineages (van der Hammen and Cleef 1986). There are six páramo units or complexes in the Department of Antioquia, located in northwestern Colombia. For five years, we conducted botanic explorations in order to quantify the richness of angiosperm flora in these units. We estimate the richness of angiosperms in these páramos at 693 species, 277 genera, and 86 families, which represent almost 10% of the floral diversity in Antioquia, but contained in only 0.7% of its area. We found that Frontino-Urrao is the most species-rich páramo with 465 species from 225 genera. Our results show that the most diverse angiosperm families of the páramos of Antioquia are Asteraceae, Orchidaceae, Melastomataceae, and Poaceae, which together represent 245 species. Groupings between páramos by Sørensen’s similarity index show that the complexes of the Central Andes Cordillera form a cluster of greater affinity than Páramos from other regions. Of the species found, 80 have a CITES or IUCN diagnosis. The expeditions allowed the identification of 21 species not previously registered in Antioquia and a considerable number of endemisms (35 species), further proof of the high plant diversity in these ecosystems. PMID:27829798

  13. 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.

  14. 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

  15. Deformation of Northwestern South America from GPS Geodesy

    NASA Astrophysics Data System (ADS)

    Mora-Paez, H.; La Femina, P. C.; Mothes, P. A.; Ruiz, A. G.; Fernandes, R. M.

    2013-12-01

    The North Andes block (NAB) is a hypothesized tectonic block that migrates (escapes) north-northeast relative to a stable South American reference frame. The motion of this block is thought-to-be derived by the collision of the Carnegie Ridge in southern Ecuador and/or by oblique convergence and high degrees of interplate coupling north of the ridge (i.e., strain partitioning). At the latitude of Ecuador, the NAB is defined by transpressional deformation accommodating east-northeastward motion along its boundary with South America. In southern to central Colombia, the NAB is dissected by several mapped and prominent regional shear zones. At these latitudes the NAB may be bound to the west by the Choco block and the transpressional Atrato-Uraba fault system and to the east by the Guayaquil-Algeciras fault system. And in northern Colombia the Caribbean - South America plate boundary is defined by the NAB and proposed Maracaibo and Guajira blocks. We investigate the deformation of northwestern South America, including the kinematics of NAB utilizing a new velocity field based on continuous GPS and existing episodic GPS data in Ecuador, Colombia, Venezuela and Panama. We reference these new velocities to a newly estimated Euler vector for the South America plate based on inversion of cGPS data from stations east of the Andes. The new velocity field and published earthquake slip vectors are inverted to solve for the Euler vectors of the NAB, Choco, Panama, Maracaibo and Guajira blocks and interseismic elastic strain accumulation (interseismic coupling) on block-bounding faults using a block modeling approach. We test a suite of block models to investigate the tectonic nature of the NAB along strike and the style of faulting in the upper plate accommodating block motion. Through the estimation of elastic strain accumulation on all block-bounding faults, we improve the understanding of interseismic coupling along a convergent margin capable of producing M>8 earthquakes

  16. Mountain building in the central Andes

    NASA Astrophysics Data System (ADS)

    Kono, Masaru; Fukao, Yoshio; Yamamoto, Akihiko

    1989-04-01

    The Central Andes is the middle part of the Andean chain between about 13°S and 27°S, characterized by the parallel running high mountain chains (the Western and Eastern Cordilleras) at the edges of high plateaus with a height of about 4000 m and a width of 200 to 450 km (the Altiplano-Puna). From the examination of geophysical and geological data in this area, including earthquakes, deformation, gravity anomaly, volcanism, uplift history, and plate motion, we conclude that the continued plate subduction with domination of compressive stress over the entire arc system is the main cause of the tectonic style of the Central Andes. We propose that the present cycle of mountain building has continued in the Cenozoic with the most active phase since the Miocene, and that the present subduction angle (30°) is not typical in that period but that subduction with more shallowly dipping oceanic lithosphere has prevailed at least since the Miocene, because of the young and buoyant slab involved. This situation is responsible for the production of a broad zone of partial melt in the mantle above the descending slab. Addition of volcanic materials was not restricted to the western edge (where active volcanoes of the Western Cordillera exist) but extended to the western and central portion of the Altiplano-Puna. The western half of the Central Andes is essentially isostatic because the heat transferred with the volcanic activities softened the crust there. In the eastern edge, the thermal effect is small, and the crust is strongly pushed by the westward moving South American plate. This caused the shortening of crustal blocks due to reverse faulting and folding in the Eastern Cordillera and Amazonian foreland. The magmatism and crustal accretion are dominant at the western end of the mountain system and decrease eastward, while the compression and consequent crustal shortening are strongest at the eastern end and wane toward west. These two processes are superposed between

  17. 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.

  18. 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)

  19. SRTM Colored Height and Shaded Relief: Laguna Mellquina, Andes Mountains, Argentina

    NASA Image and Video Library

    2001-06-14

    This depiction of an area south of San Martin de Los Andes, Argentina, is the first Shuttle Radar Topography Mission SRTM view of the Andes Mountains, the tallest mountain chain in the western hemisphere.

  20. SRTM Perspective of Colored Height and Shaded Relief Laguna Mellquina, Andes Mountains, Argentina

    NASA Image and Video Library

    2001-06-22

    This depiction of an area south of San Martin de Los Andes, Argentina, is the first Shuttle Radar Topography Mission SRTMview of the Andes Mountains, the tallest mountain chain in the western hemisphere.

  1. 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.

  2. Quaternary glaciations of the southern Andes

    NASA Astrophysics Data System (ADS)

    Rabassa, Jorge; Clapperton, Chalmers M.

    The southern Andes comprise the southernmost portion of the Andean Cordillera, beginning at the edge of the Puna Altiplano (lat.27°S) and ending at Isla de los Estados (lat.55°S). The late Cainozoic glacial record of these mountains spans the interval from the Late Miocene to the present and is one of the most complete to be found anywhere in the world. This has arisen for several reasons: (i) the conterminous mountain ice cap extended to the piedmont zone on both flanks of the range, where the sedimentary and morphological record has been well preserved; (ii) periodic volcanism, mainly from monogenetic fissure eruptions of basalt east of the range and from central tephra-producing cones along the mountain crest, has provided opportunity for the preservation and radiometric dating of interbedded glacial deposits; (iii) a tectonically-induced interval of stream incision in the Mid Pleistocene and simultaneous uplift has preserved glacial sediments on interfluves; (iv) in the Chilean lakes region west of the mountains, Late Quaternary glaciers terminated in a well-vegetated landscape, thus creating scope for radiocarbon dating of interbedded and incorporated organic materials; consequently, the last glaciation in the Llanquihue area of Chile is one of the best dated sequences in South America; thus the 'Llanquihue' Glaciation is proposed as the South American equivalent of the 'Wisconsin' and 'Weichsel' glaciations of North America and north west Europe respectively.

  3. Diversification of clearwing butterflies with the rise of the Andes.

    PubMed

    De-Silva, Donna Lisa; Elias, Marianne; Willmott, Keith; Mallet, James; Day, Julia J

    2016-01-01

    Despite the greatest butterfly diversity on Earth occurring in the Neotropical Andes and Amazonia, there is still keen debate about the origins of this exceptional biota. A densely sampled calibrated phylogeny for a widespread butterfly subtribe, Oleriina (Nymphalidae: Ithomiini) was used to estimate the origin, colonization history and diversification of this species-rich group. Neotropics. Ancestral elevation and biogeographical ranges were reconstructed using data generated from detailed range maps and applying the dispersal-extinction-cladogenesis model using stratified palaeogeographical time slice matrices. The pattern of diversification through time was examined by comparing constant and variable rate models. We also tested the hypothesis that a change in elevation is associated with speciation. The Oleriina likely originated in the Andes in the Early to Middle Miocene and rapidly diversified to include four genera all of which also originated in the Andes. These clades, together with four species groups, experienced varying spatial and temporal patterns of diversification. An overall early burst and decreasing diversification rate is identified, and this pattern is reflected for most subclades. Changes in the palaeogeological landscape, particularly the prolonged uplift of the Andes, had a profound impact on the diversification of the subtribe. The Oleriina mostly remained within the Andes and vicariant speciation resulted in some instances. Dynamic dispersal occurred with the disappearance of geological barriers such as the Acre System and the subtribe exploited newly available habitats. Our results confirm the role of the Andean uplift in the evolution of Neotropical biodiversity.

  4. 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.

  5. [Globalization, inequality, and transmission of tropical diseases in the Venezuelan Amazon].

    PubMed

    Botto-Abella, Carlos; Graterol-Mendoza, Beatriz

    2007-01-01

    Economic globalization appears to be causing greater inequalities and increased vulnerability to tropical diseases around the world. The Venezuelan Amazon population, especially the rural indigenous population, displays among the worst health indicators in the Americas. High infant mortality rates in remote indigenous populations indicate that such communities have been affected by the globalization of disease, rather than favored by globalization of health. Globalization has also influenced public policies in the country, affecting the efficiency of control programs targeting tropical diseases. A new global pact for the sustainable development of the planet is needed, supported by the globalization of human values and rights. In Venezuela, new policies for the indigenous health sector, more resources, and greater autonomy could help reduce the inequities described here in the Venezuelan Amazon.

  6. Infectious disease serologic survey in free-ranging Venezuelan anacondas (Eunectes murinus).

    PubMed

    Calle, P P; Rivas, J; Muñoz, M; Thorbjarnarson, J; Holmstrom, W; Karesh, W B

    2001-09-01

    Reptiles can harbor pathogenic microorganisms asymptomatically and serve as potential reservoirs of infection for humans, domestic animals, and other reptiles. Infectious diseases are also problematic for free-ranging reptile populations and are an important consideration in reptile reintroduction and translocation projects. There have been limited serologic studies of free-ranging reptiles for evidence of exposure to potential pathogens. In the present study, serum or plasma samples from five male and five female free-ranging Venezuelan anacondas (Eunectes murinus) were screened for antibodies to eastern, western, and Venezuelan equine encephalitis viruses, vesicular stomatitis virus, ophidian paramyxovirus, 19 Leptospira interrogans serovars, and Cryptosporidium serpentes. Antibodies to these agents were not detected, or antibody titers were low and possibly nonspecific. These results for the limited number of anacondas surveyed suggest that they do not serve as significant reservoirs for these infectious agents at this location.

  7. 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

  8. 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.

  9. Venezuelan equine encephalitis virus activity in the Gulf Coast region of Mexico, 2003-2010.

    PubMed

    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.

  10. Neuro-Immune Mechanisms in Response to Venezuelan equine encephalitis Virus Infection

    DTIC Science & Technology

    2000-05-01

    Human T-Cell Lymphotropic Virus Type 1 125 (HTLV- 1 ) Tax: Induction of Tumor Necrosis Factor Alpha and Suseptibility to Lysis...et al., 1987), Visna virus (Stowring et al., 1985), Borna virus (Carbone et al., 1991), as well as Human Immunodeficiency virus type- 1 (Tornatore et...INTRODUCTION 1 CHAPTER 2 — ASTROCYTES AS TARGETS FOR VENEZUELAN EQUINE ENCEPHALITIS VIRUS INFECTION Title Page 15 Abstract 16 Introduction 17 Material

  11. 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.

  12. A Long-Term United States’ Energy Policy Without Venezuelan Oil

    DTIC Science & Technology

    2009-04-01

    sugarcane, corn, wheat, soybeans, and palm oil in 2012, 2017, 2027 for each country and the expected percentage available for export. 140 The report... OIL by Paul B. Reinhardt, LCDR, USN A Research Report Submitted to the Faculty In Partial Fulfillment of the Graduation...Venezuelan Oil 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7

  13. Reconstructing climate variability using tree rings and glacier fluctuations in the southern Chilean Andes

    NASA Astrophysics Data System (ADS)

    Aravena, Juan-Carlos

    This thesis investigates climate variability in southern South America (south of 40°S) during the last 400 years using instrumental data, tree rings and glacier fluctuations. The dominant spatial and temporal patterns of a network of 25 homogeneous instrumental rainfall records were analyzed and used to define four regional precipitation series (1950-2000): northwestern Patagonia, central Patagonia, Patagonian plains-Atlantic, and southern Patagonia. Time series analysis of these regional patterns shows marked decadal variability for northwestern and central Patagonia, 3-7 year oscillations for Patagonian plains-Atlantic region, and a strong biannual oscillatory mode for southern Patagonia. Regional rainfall appears to be strongly influenced by Antarctic circulation modes (Antarctic Oscillation Index) while the ENSO influence on rainfall variability is less evident. Highly significant correlation of precipitation on the west coast of Patagonia with the pressure gradient between the subtropical eastern Pacific and the high-latitude south eastern Pacific is confirmed. A new network of 18 tree-ring chronologies from Pilgerodendron uviferum, an endemic conifer, was developed from sites along the western flank of the southern Andes. Highly significant series inter-correlation values ranged between 0.44 and 0.629 while mean sensitivity values ranged between 0.186 and 0.252. The series have relatively few missing rings (0.77-0.12% in individual chronologies). The oldest Pilgerodendron sampled to date was 859 years old while the chronology length ranged between 239 and 633 years. Ring-width series are correlated with precipitation but there were difficulties developing strong precipitation/ring-width relationships for individual stations/sites. However, two regional rainfall reconstructions were developed based on the inverse correlation between Pilgerodendron radial growth and the precipitation of northwestern and southern Patagonia. The reconstruction for spring

  14. Placental and fetal alterations due to Venezuelan equine encephalitis virus in rats.

    PubMed Central

    García-Tamayo, J; Esparza, J; Martínez, A J

    1981-01-01

    Histopathological changes in the placentas, embryos, and fetuses of rats inoculated intraperitoneally with the virulent Guajira strain of Venezuelan equine encephalitis virus were studied by light microscopy and immunoperoxidase methods. Rats inoculated before day 15 of pregnancy showed necrosis and hemorrhages in the embryonic disks. Swelling of cytoplasm and nuclear pyknosis of cyto- and syncytotrophoblastic cells were noted as early as 2 days after inoculation. During weeks 1 and 2 of pregnancy, death of the embryos was always observed 3 to 4 days after Venezuelan equine encephalitis virus inoculation. Placental and fetal damage varied among the specimens. In rats 18 days pregnant and sacrificed 2 days after inoculation, there were some viable fetuses; the placentas showed inflammatory reactions in the mesometrial and decidual vessels. Other rats sacrificed at 3 to 4 days after inoculation showed large placental infarcts with fetal death. Viremia peaked during day 2 after inoculation. Immunoperoxidase stains demonstrated viral antigens present in the decidua, myometrium, and cyto- and syncytotrophoblastic cells. These experiments provide additional data regarding the pathogenesis and structural damage in the placental and fetal tissues caused by Venezuelan equine encephalitis virus. Images PMID:7251148

  15. Accuracy of dental age estimation in Venezuelan children: comparison of Demirjian and Willems methods.

    PubMed

    Medina, Aída C; Blanco, Lucila

    2014-01-01

    Dental age is a somatic maturity indicator with importance in clinical and forensic dentistry. The purpose of this study is to compare the applicability of the Demirjian and Willems methods for dental age estimation in a group of Venezuelan children. Panoramic radiographs of 238 Venezuelan children aged 5-13 years were used to assess dental age using the methods described by Demirjian and Willems. Children with unclear panoramic radiographs, dental agenesis, and premature loss of primary teeth were excluded. Mean differences between dental age and chronological age by gender and age groups were estimated (ANOVA, Student tests p = 0.05). For the Demirjian method, the mean difference between dental age and chronological age was 0.62 +/- 0.93 years, statistically significant. The mean overestimation was lower for females than for males (females 0.56 +/- 0.96 years, males 0.67 +/- 0.93 years). For the Willems method, the mean difference between dental age and chronological age was 0.15 +/- 0.97 years, not statistically significant. Accuracy was significantly different between genders, performing best for females (females 0.01 +/- 0.96 years, males 0.29 +/- 0.96 years). The Willems method for age estimation was found to be more accurate than the Demirjian method in this sample of Venezuelan children.

  16. 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

  17. 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.

  18. MISR Images Wildfires in Northwestern US

    NASA Image and Video Library

    2000-08-16

    These images from NASA Terra satellite are of smoke plumes from devastating wildfires in the northwestern U.S. This view of the Clearwater and Salmon River Mountains in Idaho was acquired on August 5, 2000 Terra orbit 3370.

  19. Old growth in northwestern California national forests.

    Treesearch

    Debby Beardsley; Ralph. Warbington

    1996-01-01

    This report estimates old-growth forest area and summarizes stand characteristics of old growth in northwestern California National Forests by forest type. Old-growth definitions for each forest type are used.

  20. 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)

  1. Vector Competence of Peruvian Mosquitoes (Diptera:Culicidae) for a Subtype IIIC Strain in the Venezuelan Equine Encephalomyelitis Complex Isolated from Mosquitoes Captured in Peru

    DTIC Science & Technology

    2006-03-01

    strains of Venezuelan equine encephalitis virus. J Am Mosq Control Assoc 15:295–298. Turell MJ, Gargan TP II, Bailey CL. 1984. Replication and dissemination...Venezuelan equine encephalitis (VEE) complex alphavirus by Culex (Melanoconion) gnomatos (Diptera: Culicidae) in northeastern Peru. J Med Entomol 42:404–408

  2. 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.

  3. 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…

  4. Andes Hantavirus Variant in Rodents, Southern Amazon Basin, Peru

    PubMed Central

    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.

    2014-01-01

    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. PMID:24447689

  5. 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…

  6. 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

  7. Stable oxygen isotopes ( δ 18O) in Austrocedrus chilensis tree rings reflect climate variability in northwestern Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

    The stable oxygen isotope ( δ 18O) 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 δ 18O 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 δ 18O 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.

  8. 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.

  9. Provenance of Cretaceous-Pliocene Clastic Sediments in the Tachira Saddle, Western Venezuela, and Implications for Sediment Dispersal Patterns in the Northern Andes

    NASA Astrophysics Data System (ADS)

    Gomez, Ali Ricardo

    Northwestern South America is highly deformed due to the transpressive plate boundary associated with complex interactions between the Caribbean plate, the South American plate, the Nazca plate and the Panama arc. Previous studies suggest that the Cenozoic uplift of the Merida Andes and Eastern Cordillera of Colombia affected sediment dispersal patterns in the region, shifting from a Paleocene foreland basin configuration to the modern isolated basins. Well-exposed Cretaceous to Pliocene strata in the Tachira Saddle provides a unique opportunity to test proposed sediment dispersal patterns in the region. U-Pb detrital zircon geochronology and supplementary XRD heavy mineral data are used together to document the provenance of the Tachira Saddle sediments and refine the sediment dispersal patterns in the region. Results from the U-Pb detrital zircon geochronology show that there are six age groups recorded in these samples. Two groups are related to the Precambrian Guyana shield terranes and Putumayo basement in the Eastern Cordillera, and four groups are related to different magmatic episodes occurring during the Andean orogenic process. The transition between the Cretaceous passive margin and the Paleocene foreland basin and the initial uplift of the Eastern Cordillera and the uplift of the Merida Andes by the Early Miocene were also recorded in the Tachira saddle detrital zircon signature.

  10. 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

  11. 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.

  12. Isonymy structure of Sucre and Táchira, two Venezuelan states.

    PubMed

    Rodríguez-Larralde, A; Barrai, I

    1997-10-01

    The isonymy structure of two Venezuelan states, Sucre and Táchira, is described using the surnames of the Register of Electors updated in 1991. The frequency distribution of surnames pooled together by sex was obtained for the 57 counties of Sucre and the 52 counties of Táchira, based on total population sizes of 158,705 and 160,690 individuals, respectively. The coefficient of consanguinity resulting from random isonymy (phi ii), Karlin and McGregor's ni (identical to v), and the proportion of the population included in surnames represented only once (estimator A) and in the seven most frequent surnames (estimator B) were calculated for each county. RST, a measure of microdifferentiation, was estimated for each state. The Euclidean distance between pairs of counties within states was calculated together with the corresponding geographic distances. The correlations between their logarithmic transformations were significant in both cases, indicating differentiation of surnames by distance. Dendrograms based on the Euclidean distance matrix were constructed. From them a first approximation of the effect of internal migration within states was obtained. Ninety-six percent of the coefficient of consanguinity resulting from random isonymy is determined by the proportion of the population included in the seven most frequent surnames, whereas between 72% and 88% of Karlin and McGregor's ni for Sucre and Táchira, respectively, is determined by the proportion of population included in surnames represented only once. Surnames with generalized and with focal distribution were identified for both states, to be used as possible indicators of the geographic origin of their carriers. Our results indicate that Táchira's counties, on average, tend to be more isolated than Sucre's counties, as measured by RST, estimator B, and phi ii. Comparisons with the results obtained for other. Venezuelan states and other non-Venezuelan populations are also given.

  13. Characterization of Tityus scorpion venoms using synaptosome binding assays and reactivity towards Venezuelan and Brazilian antivenoms.

    PubMed

    Borges, Adolfo; De Sousa, Leonardo; Espinoza, Jorge; Melo, Marilia Martins; Santos, Raquel G; Kalapothakis, Evanguedes; Valadares, Diogo; Chávez-Olórtegui, Carlos

    2008-01-01

    Venoms from Tityus species inhabiting five endemic regions of scorpionism in Venezuela (Andean, Perijá range, north-central, northeastern, and Guayana) and also southeast Brazil (T. serrulatus and T. bahiensis) were characterized immunologically in ELISA experiments using mouse- and rabbit-derived antibodies to evaluate their cross-reactivity and also functionally, utilizing synaptosome binding assays. While Brazilian and Venezuelan antivenoms cross-reacted poorly, T. discrepans (north-central Venezuela) and T. zulianus (Andean) venoms shared a greater immunological relatedness than with T. perijanensis (Perijá range). Anti-T. breweri (Guayana) antibodies fully cross-reacted with T. discrepans. Native PAGE indicated species-specific fingerprints for all venoms and revealed differences between two populations (Anzoátegui and Monagas States) of T. nororientalis (northeastern Venezuela). Components antigenically related to T. serrulatus beta-toxin TsVII were also detected in T. breweri, T. nororientalis (Anzoátegui) and T. funestus (Andean). Antibodies against T. serrulatus anatoxin TsNTxP did not cross-react significantly with any Venezuelan venoms indicating lack of TsNTxP homologues. The results suggest that the extent of antigenic reactivity depends on the studied species rather than the geographical distance between their habitats. All venoms, with T. discrepans to a lesser extent, were able to significantly displace [(125)I]-TsVII from its binding site in rat brain synaptosomes. Our data indicate that beta-toxins functionally related to TsVII but differing significantly in their antigenic regions exist in Venezuelan venoms from different endemic regions. Identification of shared epitopes with TsVII, at least for some species, may lead to the design of antibodies based on common epitopes for treating scorpion envenoming in Venezuela and Brazil.

  14. CD4+ T cells provide protection against acute lethal encephalitis caused by Venezuelan equine encephalitis virus.

    PubMed

    Yun, Nadezhda E; Peng, Bi-Hung; Bertke, Andrea S; Borisevich, Viktoriya; Smith, Jennifer K; Smith, Jeanon N; Poussard, Allison L; Salazar, Milagros; Judy, Barbara M; Zacks, Michele A; Estes, D Mark; Paessler, Slobodan

    2009-06-19

    Studying the mechanisms of host survival resulting from viral encephalitis is critical to the development of vaccines. Here we have shown in several independent studies that high dose treatment with neutralizing antibody prior to intranasal infection with Venezuelan equine encephalitis virus had an antiviral effect in the visceral organs and prolonged survival time of infected mice, even in the absence of alphabeta T cells. Nevertheless, antibody treatment did not prevent the development of lethal encephalitis. On the contrary, the adoptive transfer of primed CD4(+) T cells was necessary to prevent lethal encephalitis in mice lacking alphabeta T cell receptor.

  15. Laboratory Transmission of Venezuelan Equine Encephalomyelitis Virus by the Tick Hyalomma Truncatum

    DTIC Science & Technology

    1994-01-01

    equine On day 21 after infestation of the first guinea-pig, none encephalomyelitis virus by the tick of 95 unfed nv mphs sampled contained virus...Epi/ootic strains oft Venezuelan equine encephalo- nymphs [minimum infection rate =2 200 1% I"( 1 contained inveliti. \\EE’ virus Alp/tavirus. family...Togaviridae virus mean titre= 102 1 1PFU ’. About 200 unfed nymphs ý:iuse serious disease tin horse % and humans throughout were placed on a guinea-pig at

  16. [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.

  17. 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

  18. Crustal thickness estimates of Northwestern South America and their relation to the presence of batholithic bodies of economy interest

    NASA Astrophysics Data System (ADS)

    Hernandez, O.; von Frese, R. R.; Potts, L. M.

    2007-05-01

    A new model for the crustal evolution of northwestern South America (-8 S to 23.5 N, -90 W to -58.5 W) was developed from gravity derived MOHO depth estimates and tectonic features interpreted from correlative geopotential anomalies and seismic data. Crustal thickness estimates provide important constraints on the distribution of volcanic and seismic hazards, and mineral and energy deposits. Crustal thickness estimates were obtained by inversion of the compensated terrain gravity effects (CTGE) and compared against theoretical Airy MOHO and compiled seismic MOHO estimates. The thickness of the continental crust varies from 35 km to 55 km and shows that the mountain ranges are partially compensated by continental roots. The volumetric proportions of erupted rock types and geochemical characteristics likely are strongly correlated with the thickness and chemical characteristics of the crust through which the rising magmas travel. Crustal thicknesses from 45 to 55 km at the continent are related to the presence of andesitic batholiths of economic interest. Major deposits of base and precious metals of the Andean Mountains are related to intermediate to felsic intrusions. Porphyry copper-molybdenum deposits coincide with Mesozoic - Cenozoic orogenic belts and calc- alkaline volcanism. Major batholiths in the Central Andes, are related to gravity-inferred crustal thicknesses between 55 km to 60 km. Therefore, these results suggest that exploration of mineral deposits associated with batholithic intrusions in the Andes Mountains can be extended to crustal thicknesses from 45 km to 60 km.

  19. 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

  20. 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.

  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. Synchronous interhemispheric Holocene climate trends in the tropical Andes.

    PubMed

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

    2013-09-03

    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.

  3. EFFECT OF ADJUVANTS ON ANTIBODY RESPONSE OF RABBITS INOCULATED WITH VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS

    PubMed Central

    Shepel, Michael; Klugerman, Maxwell R.

    1963-01-01

    Shepel, Michael (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.) and Maxwell R. Klugerman. Effect of adjuvants on antibody response of rabbits inoculated with Venezuelan equine encephalomyelitis virus. J. Bacteriol. 85:1150–1155. 1963.—Hemagglutination-inhibition, neutralization, and complement-fixation tests were performed on sera of rabbits inoculated with Venezuelan equine encephalomyelitis (VEE) virus in combination with Freund's adjuvants and in Hank's salt solution. This study indicated that the complete adjuvants (i.e., with mycobacteria) considerably increased the antibody response to VEE virus. Mycobacterium butyricum (M. smegmatis) appeared to be more effective than M. tuberculosis H37Ra. In the absence of mycobacteria, the response was much less pronounced. Paper electrophoretic studies of the antisera demonstrated a marked increase in gamma-globulin production, an increase in the beta-globulin, and an increase in total protein as the result of adding VEE virus to the complete adjuvants. A decrease in the albumin fraction appeared to be caused by the complete adjuvants rather than by the VEE virus itself. The incomplete adjuvant (without mycobacteria) plus virus contributed little, if any, stimulation toward the production of gamma-globulin, nor did it appear to affect the serum-albumin levels. Images PMID:14044008

  4. Genetic diversity and relationships among Venezuelan equine encephalitis virus field isolates from Colombia and Venezuela.

    PubMed

    Moncayo, A C; Medina, G M; Kalvatchev, Z; Brault, A C; Barrera, R; Boshell, J; Ferro, C; Freier, J E; Navarro, J C; Salas, R; De Siger, J; Vasquez, C; Walder, R; Weaver, S C

    2001-12-01

    During field studies of enzootic Venezuelan equine encephalitis (VEE) viruses associated with epizootic emergence, a large number of virus isolates were made in sylvatic foci of Venezuela and Colombia. To rapidly characterize these isolates, antigenic subtypes were determined by means of immunofluorescence and by single-strand conformational polymorphism (SSCP) analysis by use of an 856-bp fragment from the P62 gene, which we used to distinguish genetic variants. Representative isolates were sequenced to assess the sensitivity of SSCP to detect genetic differences. The SSCP analysis distinguished isolates differing by as little as 1 nucleotide; overall, differences of > or = 1 nucleotide were recognized 89% of the time, and the sensitivity to distinguish strains that differed by only 1 or 4 nucleotides was 17 and 57%, respectively. Phylogenetic analyses of representative sequences showed that all recent isolates from the Catatumbo region of western Venezuela and the middle Magdalena Valley of Colombia were closely related to epizootic subtype IAB and IC strains; strains from Yaracuy and Miranda States were more distantly related. Cocirculation of the same virus genotype in both Colombian and Venezuelan foci indicated that these viruses are readily transported between enzootic regions separated by > 300 km. The SSCP analysis appears to be a simple, fast, and relatively efficient method of screening VEE virus isolates to identify meaningful genetic variants.

  5. A Phase-1 Clinical Trial of a DNA Vaccine for Venezuelan Equine Encephalitis Delivered by Intramuscular or Intradermal Electroporation

    DTIC Science & Technology

    2016-05-25

    for public release; distribution is unlimited. UNCLASSIFIED 2 Abstract Background Venezuelan equine encephalitis virus (VEEV) is a mosquito -borne...virus (VEEV) is an mosquito -borne alphavirus that causes periodic epizootics in the Americas, with infected equines serving as amplifying hosts [1

  6. Analysis of the CFTR gene in Venezuelan cystic fibrosis patients, identification of six novel cystic fibrosis-causing genetic variants

    PubMed Central

    Sánchez, Karen; de Mendonca, Elizabeth; Matute, Xiorama; Chaustre, Ismenia; Villalón, Marlene; Takiff, Howard

    2016-01-01

    The mutations in the CFTR gene found in patients with cystic fibrosis (CF) have geographic differences, but there are scant data on their prevalence in Venezuelan patients. This study determined the frequency of common CFTR gene mutations in a group of Venezuelan patients with CF. The 27 exons of the CFTR gene from 110 Venezuelan patients in the National CF Program were amplified and sequenced. A total of 36 different mutations were identified, seven with frequencies greater than 1%: p.Phe508del (27.27%), p.Gly542* (3.18%), c.2988+1G>A (3.18%), p.Arg334Trp (1.36%), p.Arg1162* (1.36%), c.1-8G>C (1.36%), and p.[Gly628Arg;Ser1235Arg](1.36). In 40% of patients, all with a clinical diagnosis of CF, no mutations were found. This report represents the largest cohort of Venezuelan patients with CF ever examined, and includes a wider mutation panel than has been previously studied in this population. Mutations common in Southern European populations predominate, and several new mutations were discovered, but no mutations were found in 40% of the cohort. PMID:27022295

  7. Analysis of the CFTR gene in Venezuelan cystic fibrosis patients, identification of six novel cystic fibrosis-causing genetic variants.

    PubMed

    Sánchez, Karen; de Mendonca, Elizabeth; Matute, Xiorama; Chaustre, Ismenia; Villalón, Marlene; Takiff, Howard

    2016-01-01

    The mutations in the CFTR gene found in patients with cystic fibrosis (CF) have geographic differences, but there are scant data on their prevalence in Venezuelan patients. This study determined the frequency of common CFTR gene mutations in a group of Venezuelan patients with CF. The 27 exons of the CFTR gene from 110 Venezuelan patients in the National CF Program were amplified and sequenced. A total of 36 different mutations were identified, seven with frequencies greater than 1%: p.Phe508del (27.27%), p.Gly542* (3.18%), c.2988+1G>A (3.18%), p.Arg334Trp (1.36%), p.Arg1162* (1.36%), c.1-8G>C (1.36%), and p.[Gly628Arg;Ser1235Arg](1.36). In 40% of patients, all with a clinical diagnosis of CF, no mutations were found. This report represents the largest cohort of Venezuelan patients with CF ever examined, and includes a wider mutation panel than has been previously studied in this population. Mutations common in Southern European populations predominate, and several new mutations were discovered, but no mutations were found in 40% of the cohort.

  8. Sino-American Relations in the 21st Century: Taking a Page from the Venezuelan Crisis of 1895

    DTIC Science & Technology

    2015-04-13

    of the more vociferous Congressmen, went on to use the Venezuelan crisis as a bully pulpit for his anti-English views...tone of the press was conciliatory.”4 These messages had a positive impact on Americans’ view of Britain, and were the first step in easing tensions

  9. 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.

  10. 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.

  11. 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.

  12. Synthetic Seismogram Study of the Eastern Central Andes

    DTIC Science & Technology

    2008-09-30

    gaps located in the coupling zone of the Nazca and the South American plates. The above-mentioned earthquakes were here used to generate the...the limits of gaps located in the coupling zone of the Nazca and the South American plates. The above-mentioned earthquakes were here used to generate...surrounding areas. RESEARCH PERFORMED The area of study is located in the Eastern Central Andes, in the region where the Nazca Plate subducts at 300

  13. Amplified warming at high elevation in the tropical Andes? (Invited)

    NASA Astrophysics Data System (ADS)

    Vuille, M. F.; Buytaert, W.; Zulkafli, Z.; Franquist, E.

    2013-12-01

    Theoretical and modeling studies suggest that adjustment of the moist-adiabatic lapse rate due to continued greenhouse gas radiative forcing will lead to accelerated warming of tropical high-elevation mountain regions in the 21st century. The scarcity of observational data at high-elevation sites in the tropics, however, has complicated the unambiguous detection and potential attribution of such a warming signal. Here we will focus on the tropical Andes, where such an enhanced warming is of special concern, given the important ecosystem services provided by wetlands and glaciers, both being very sensitive to enhanced warming and resulting changes in evaporation, melt rates, snow-rain ratios, etc. This presentation will review the potential of various feedbacks, such as snow-albedo feedback, water vapor feedback, lapse rate feedback and others to produce differential warming rates at different elevations in the Andes. These theoretical considerations will then be compared with the latest available observational and modeling results regarding evidence (or lack thereof) for enhanced warming at high elevation sites. Our analysis relies on an updated database of more than 850 stations from different elevations along the Andes, complemented by projections for several representative concentration pathways (RCP's) from the CMIP5 multi-model ensemble.

  14. Radiocarbon chronology of the last glacial maximum and its termination in northwestern Patagonia

    NASA Astrophysics Data System (ADS)

    Moreno, Patricio I.; Denton, George H.; Moreno, Hugo; Lowell, Thomas V.; Putnam, Aaron E.; Kaplan, Michael R.

    2015-08-01

    We examine the timing and magnitude of the last glacial maximum (LGM) and the last glacial termination (LGT) in northwestern Patagonia, situated in the middle latitudes of South America. Our data indicate that the main phase of the LGT began with abrupt warm pulses at 17,800 and 17,100 cal yrs BP, accompanied by rapid establishment of evergreen temperate rainforests and extensive deglaciation of the Andes within 1000 years. This response shows that South American middle-latitude temperatures had approached average interglacial values by 16,800 cal yrs BP. The temperature rise in northwestern Patagonia coincides with the beginning of major warming and glacier recession in the Southern Alps of New Zealand at southern mid-latitudes on the opposite side of the Pacific Ocean. From this correspondence, the warming that began at 17,800 cal yrs BP appears to have been widespread in middle latitudes of the Southern Hemisphere, accounting for at least 75% of the total temperature recovery from the LGM to the Holocene. Moreover, this warming pulse is coeval with the first half of the Heinrich Stadial 1 (HS1) in the North Atlantic region. HS1 featured a decline of North Atlantic meridional overturning circulation, a southward shift of the westerly wind belt in both hemispheres and of the Intertropical Convergence Zone, as well as a weakening of the Asian monsoon. Along with the initiating trigger, identifying the mechanisms whereby these opposing climate signals in the two polar hemispheres interacted -whether through an oceanic or an atmospheric bipolar seesaw, or both- lies at the heart of understanding the LGT.

  15. Herpetological conservation in northwestern North America

    Treesearch

    Deanna H. Olson

    2009-01-01

    Conservation of the 105 species of amphibians, reptiles, and turtles in the northwestern United States and western Canada is represented by a diverse mix of projects and programs across ten states, provinces, and territories. In this paper, 29 contributing authors review the status of herpetofauna by state, province or territory, and summarize the key issues, programs...

  16. Timber resource of Missouri's Northwestern Ozarks, 1972.

    Treesearch

    Alexander Vasilevsky; Burton L. Essex

    1974-01-01

    The third timber inventory of Missouri's Northwestern Ozarks Forest Survey Unit shows substantial gains in both growing-stock and sawtimber volumes between 1959 and 1972. The area of commercial forests declined during the same period. Presented are highlights and statistics on forest area and timer volume, growth, mortality, ownership and use in 1972.

  17. Multiagent Vaccines Vectored by Venezuelan Equine Encephalitis Virus Replicon Elicits Immune Responses to Marburg Virus and Protection Against Anthrax and Botulinum Neurotoxin in Mice

    DTIC Science & Technology

    2006-01-01

    formulations of individual Venezuelan equine encephalitis (VEE) virus replicon- vectored vaccines against a bacterial disease, anthrax; a viral disease...here the results of using formulations of individual Venezuelan equine encephalitis (VEE) virus replicon-vectored vaccines against a bacterial disease...on days 0, 35, and 70 with the indicated vaccines. Ne b Infectious units were used to measure VRP and milliliters were used to measur c The

  18. Induction and Characterization of Immune Responses in Small Animals Using a Venezuelan Equine Encephalitis Virus (VEE) Replicon System, Expressing Human Immunodeficiency Virus Type 1 (HIV-1) Envelope Genes

    DTIC Science & Technology

    2003-01-01

    Montelaro, and C. J. Issel. 1995. Enhanced sensitivity to neutralizing antibodies in a variant of equine infectious anemia virus is linked to amino acid...371-8. 64 36. Davis, N. L., L. V. Willis, J. F. Smith, and R. E. Johnston. 1989. In vitro synthesis of infectious venezuelan equine encephalitis...Characterization of Immune Responses in small animals using a Venezuelan Equine Encephalitis Virus (VEE) Replicon System, Expressing Human

  19. 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.

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

    PubMed

    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

    2015-05-01

    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.

  1. Candidate Vectors and Rodent Hosts of Venezuelan Equine Encephalitis Virus, Chiapas, 2006–2007

    PubMed Central

    Deardorff, Eleanor R.; Estrada-Franco, Jose G.; Freier, Jerome E.; Navarro-Lopez, Roberto; Da Rosa, Amelia Travassos; Tesh, Robert B.; Weaver, Scott C.

    2011-01-01

    Enzootic Venezuelan equine encephalitis virus (VEEV) has been known to occur in Mexico since the 1960s. The first natural equine epizootic was recognized in Chiapas in 1993 and since then, numerous studies have characterized the etiologic strains, including reverse genetic studies that incriminated a specific mutation that enhanced infection of epizootic mosquito vectors. The aim of this study was to determine the mosquito and rodent species involved in enzootic maintenance of subtype IE VEEV in coastal Chiapas. A longitudinal study was conducted over a year to discern which species and habitats could be associated with VEEV circulation. Antibody was rarely detected in mammals and virus was not isolated from mosquitoes. Additionally, Culex (Melanoconion) taeniopus populations were found to be spatially related to high levels of human and bovine seroprevalence. These mosquito populations were concentrated in areas that appear to represent foci of stable, enzootic VEEV circulation. PMID:22144461

  2. Antibody to the E3 Glycoprotein Protects Mice against Lethal Venezuelan Equine Encephalitis Virus Infection▿

    PubMed Central

    Parker, Michael D.; Buckley, Marilyn J.; Melanson, Vanessa R.; Glass, Pamela J.; Norwood, David; Hart, Mary Kate

    2010-01-01

    Six monoclonal antibodies were isolated that exhibited specificity for a furin cleavage site deletion mutant (V3526) of Venezuelan equine encephalitis virus (VEEV). These antibodies comprise a single competition group and bound the E3 glycoprotein of VEEV subtype I viruses but failed to bind the E3 glycoprotein of other alphaviruses. These antibodies neutralized V3526 virus infectivity but did not neutralize the parental strain of Trinidad donkey (TrD) VEEV. However, the E3-specific antibodies did inhibit the production of virus from VEEV TrD-infected cells. In addition, passive immunization of mice demonstrated that antibody to the E3 glycoprotein provided protection against lethal VEEV TrD challenge. This is the first recognition of a protective epitope in the E3 glycoprotein. Furthermore, these results indicate that E3 plays a critical role late in the morphogenesis of progeny virus after E3 appears on the surfaces of infected cells. PMID:20926570

  3. The Rey Auditory Verbal Learning Test: normative data developed for the Venezuelan population.

    PubMed

    Ferreira Correia, Aline; Campagna Osorio, Ilva

    2014-03-01

    The Rey Auditory Verbal Learning Test (RAVLT) is a neuropsychological tool widely used to assess functions such as attention, memory, and learning ability in the auditory-verbal domain. Norms for the test have been developed in many different languages and they show different relationships with demographic variables. The main objective of this research was to develop specific norms for the Venezuelan population, with particular focus on the influences of age, education, gender, and socioeconomic status. A Spanish version of the test was administered to a quota sample of 629 healthy adults. Pearson's correlation analysis (p < .001) showed a significant association between RAVLT performance and age (r = -.401), education (r = .386), and socioeconomic status (r = -.196), but not between RAVLT performance and gender (r = -.054). Due to the strength of the correlations, only age and education were considered in the development of final norms.

  4. Experimental Infection of Potential Reservoir Hosts with Venezuelan Equine Encephalitis Virus, Mexico

    PubMed Central

    Deardorff, Eleanor R.; Forrester, Naomi L.; Travassos da Rosa, Amelia P.; Estrada-Franco, Jose G.; Navarro-Lopez, Roberto; Tesh, Robert B.

    2009-01-01

    In 1993, an outbreak of encephalitis among 125 affected equids in coastal Chiapas, Mexico, resulted in a 50% case-fatality rate. The outbreak was attributed to Venezuelan equine encephalitis virus (VEEV) subtype IE, not previously associated with equine disease and death. To better understand the ecology of this VEEV strain in Chiapas, we experimentally infected 5 species of wild rodents and evaluated their competence as reservoir and amplifying hosts. Rodents from 1 species (Baiomys musculus) showed signs of disease and died by day 8 postinoculation. Rodents from the 4 other species (Liomys salvini, Oligoryzomys fulvescens, Oryzomys couesi, and Sigmodon hispidus) became viremic but survived and developed neutralizing antibodies, indicating that multiple species may contribute to VEEV maintenance. By infecting numerous rodent species and producing adequate viremia, VEEV may increase its chances of long-term persistence in nature and could increase risk for establishment in disease-endemic areas and amplification outside the disease-endemic range. PMID:19331726

  5. 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

    2015-04-02

    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.

  6. Natural enzootic vectors of Venezuelan equine encephalitis virus, Magdalena Valley, Colombia.

    PubMed

    Ferro, Cristina; Boshell, Jorge; Moncayo, Abelardo C; Gonzalez, Marta; Ahumada, Marta L; Kang, Wenli; Weaver, Scott C

    2003-01-01

    To characterize the transmission cycle of enzootic Venezuelan equine encephalitis virus (VEEV) strains believed to represent an epizootic progenitor, we identified natural vectors in a sylvatic focus in the middle Magdalena Valley of Colombia. Hamster-baited traps were placed into an active forest focus, and mosquitoes collected from each trap in which a hamster became infected were sorted by species and assayed for virus. In 18 cases, a single, initial, high-titered mosquito pool representing the vector species was identified. These vectors included Culex (Melanoconion) vomerifer (11 transmission events), Cx. (Mel.) pedroi (5 transmissions) and Cx. (Mel.) adamesi (2 transmissions). These results extend the number of proven enzootic VEEV vectors to 7, all of which are members of the Spissipes section of the subgenus Melanoconion. Our findings contrast with previous studies, which have indicated that a single species usually serves as the principal enzootic VEEV vector at a given location.

  7. 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.

  8. 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.

  9. 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

  10. [Spatial-Temporal variability of aquatic plant communities in the Venezuelan Llanos].

    PubMed

    Rial B, Anabel

    2006-06-01

    The richness and abundance of aquatic plant communities were studied in 14 habitats of the Venezuelan "llanos" (07 degrees 35'-07 degrees 55' N-68 degrees 50'-69 degrees 00' W, Apure) during an annual cycle. Annual means were 27 degrees C, 115 mm rainfall and 77% relative humidity. A permanent transect was set in each habitat (ten consecutive square meter quadrats from the shore to the water). The plants and the area they covered in each quadrat were recorded monthly for a year. The total richness was 69 species. Alatalo and Alatalo's diversity analysis indicates that season, and its correlate, water level, influence species diversity and abundance more than habitat (spatial factor: geometric index-Euclidean distance).

  11. Cryptosporidiosis in HIV-infected Venezuelan adults is strongly associated with acute or chronic diarrhea.

    PubMed

    Certad, Gabriela; Arenas-Pinto, Alejandro; Pocaterra, Leonor; Ferrara, Giuseppe; Castro, Julio; Bello, Andreina; Núñez, Luz

    2005-07-01

    A cross-sectional study was undertaken to determine the prevalence of cryptosporidiosis and its clinical and laboratory pattern in Venezuelan HIV-infected patients (N = 397). At enrollment, they underwent thorough clinical history and physical examination and provided stool specimens for the identification of Cryptosporidium sp. and other parasites. Cryptosporidium sp. was identified in 59 subjects (15%). This infection was strongly associated with acute and chronic diarrhea, weight loss, CD4(+) counts below 100 cells/mm(3), older age in patients with leukopenia, and more than 5 stools per day when CD4(+) counts were below 100 cells/mm(3). In addition, patients with Cryptosporidium infection were less likely to be coinfected with Isospora belli (OR = 0.05, P = 0.001). In fact, results of the current study confirm the worldwide importance of cryptosporidiosis as a clinically significant opportunistic infection associated with an advanced stage of immunosuppression.

  12. Recombinant vaccinia/Venezuelan equine encephalitis (VEE) virus expresses VEE structural proteins.

    PubMed

    Kinney, R M; Esposito, J J; Johnson, B J; Roehrig, J T; Mathews, J H; Barrett, A D; Trent, D W

    1988-12-01

    cDNA molecules encoding the structural proteins of the virulent Trinidad donkey and the TC-83 vaccine strains of Venezuelan equine encephalitis (VEE) virus were inserted under control of the vaccinia virus 7.5K promoter into the thymidine kinase gene of vaccinia virus. Synthesis of the capsid protein and glycoproteins E2 and E1 of VEE virus was demonstrated by immunoblotting of lysates of CV-1 cells infected with recombinant vaccinia/VEE viruses. VEE glycoproteins were detected in recombinant virus-infected cells by fluorescent antibody (FA) analysis performed with a panel of VEE-specific monoclonal antibodies. Seven E2-specific epitopes and two of four E1-specific epitopes were demonstrated by FA.

  13. Recombinant vaccinia virus/Venezuelan equine encephalitis (VEE) virus protects mice from peripheral VEE virus challenge.

    PubMed

    Kinney, R M; Esposito, J J; Mathews, J H; Johnson, B J; Roehrig, J T; Barrett, A D; Trent, D W

    1988-12-01

    Mice immunized with recombinant vaccinia virus (VACC) expressing Venezuelan equine encephalitis (VEE) virus capsid protein and glycoproteins E1 and E2 or with attenuated VEE TC-83 virus vaccine developed VEE-specific neutralizing antibody and survived intraperitoneal challenge with virulent VEE virus strains including Trinidad donkey (subtype 1AB), P676 (subtype 1C), 3880 (subtype 1D), and Everglades (subtype 2). However, unlike immunization with TC-83 virus, immunization with the recombinant VACC/VEE virus did not protect mice from intranasal challenge with VEE Trinidad donkey virus. These results suggest that recombinant VACC/VEE virus is a vaccine candidate for equines and humans at risk of mosquito-transmitted VEE disease but not for laboratory workers at risk of accidental exposure to aerosol infection with VEE virus.

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

    PubMed Central

    Powers, C D; Dickerman, R W

    1975-01-01

    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. PMID:1112617

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Association of common variants on chromosome 8q24 with gastric cancer in Venezuelan patients.

    PubMed

    Labrador, Luis; Torres, Keila; Camargo, Maria; Santiago, Laskhmi; Valderrama, Elvis; Chiurillo, Miguel Angel

    2015-07-15

    Gastric cancer remains one of the leading causes of death in the world, being Central and South America among the regions showing the highest incidence and mortality rates worldwide. Although several single nucleotide polymorphisms (SNPs) identified in the chromosomal region 8q24 by genome-wide association studies have been related with the risk of different kinds of cancers, their role in the susceptibility of gastric cancer in Latin American populations has not been evaluated yet. Hereby, we performed a case-control study to explore the associations between three SNPs at 8q24 and gastric cancer risk in Venezuelan patients. We analyzed rs1447295, rs4733616 and rs6983267 SNPs in 122 paraffin-embedded tumor samples from archival bank and 129 samples with chronic gastritis (obtained by upper endoscopy during the study) from the Central Hospital of Barquisimeto (Lara, Venezuela). Genotypes were determined by PCR-RFLP reactions designed in this study for efficient genotyping of formalin-fixed/paraffin-embedded tissues. No significant differences in genotype frequencies between case and control groups were found. However, carriers of the homozygous TT genotype of SNP rs4733616 had an increased risk of developing poorly differentiated gastric cancer according to the codominant (OR=3.59, P=0.035) and the recessive models (OR=4.32, P=0.014, best-fitting model of inheritance), adjusted by age and gender. Our study suggests that the SNP rs4733616 is associated with susceptibility to poorly differentiated gastric cancer in Venezuelans. Additional studies are needed to further interrogate the prognostic value of the rs4733616 marker in this high-risk population for gastric cancer.

  20. [Cut-off point of epicardial adipose tissue thickness for predicting metabolic syndrome in Venezuelan population].

    PubMed

    Lima-Martínez, Marcos M; Paoli, Mariela; Donis, José H; Odreman, Rodolfo; Torres, Christopher; Iacobellis, Gianluca

    2013-12-01

    To define an echocardiographically-assessed cut-off point for epicardial adipose tissue (EAT) thickness associated to metabolic syndrome (MS) components in Venezuelan subjects. Fifty-two subjects aged 20-65 years diagnosed with MS according to International Diabetes Federation criteria and 45 sex- and age-matched controls were selected. Blood glucose and plasma lipids were tested; EAT thickness and left ventricular mass were measured by echocardiography. No significant age and sex differences were found between the two groups. Body weight, body mass index, waist circumference, and systolic and diastolic blood pressure were significantly higher (P=.0001) in the MS group. This group showed significantly higher levels of fasting blood glucose (P=.0001), total cholesterol (P=.002), LDL-C (P=.007), non-HDL-C (P=.0001), triglycerides (P=.0001), Tg-HDL-C ratio (P=.0001), and lower HDL-C levels (P=.0001) as compared to the control group. EAT thickness (P=.0001) and left ventricular mass (P=.017) were significantly higher in the MS group. The ROC curve showed an AUC of 0.852 (P=.0001) with a power of the test of 0.99. A 5-mm EAT thickness showed a sensitivity of 84.62% (95%CI: 71.9-93.1) and a specificity of 71.11% (95%CI: 55.7-83.6) for predicting MS. The odds ratio of this population for experiencing MS due to an EAT ≥ 5 mm was 8.25 (95%CI: 3.15-21.56; P=.0001). An EAT value ≥ 5 mm has good sensitivity and specificity for predicting MS in the Venezuelan population. Copyright © 2012 SEEN. Published by Elsevier Espana. All rights reserved.

  1. Prevalence and risk factors of human papillomavirus infection in asymptomatic women in a Venezuelan urban area.

    PubMed

    Núñez-Troconis, José; Delgado, Mariela; González, Julia; Mindiola, Raimy; Velásquez, Jesvy; Conde, Betty; Whitby, Denise; Munroe, David J

    2009-06-01

    The purpose of this study was to investigate the prevalence and risk factors of genital human papillomavirus (HPV) infection in asymptomatic women, using the HPV DNA Hybrid Capture 2 (HC2) test. Three hundred and two women who attended the Out-Patient Gynecological Clinic of a tertiary level hospital, in a Venezuelan urban area, were selected for the study. A pap smear, a cervical swab for HC2 and gynecological exam were performed to each patient. The HC2 testing showed that 47 samples (15.6%) were positive to HPV. Forty patients (13.2%) were positive to high risk-HPV (HR-HPV) and 11 (3.6%) were positive to low-risk-HPV (LR-HPV). The prevalence of HPV infections was higher for women under 35 years (51.1%; p < 0.02), and decreased to 6.4% for women > or =65 years old. Women who had not finished high school had a higher prevalence of HPV infection (p < 0.035). Twenty six (42.6%) of 61 pathological Pap smears were positives to HPV infection. A statistically significant difference was found when HPV infection was compared in normal and abnormal Pap smear (HSIL+LSIL; p < 0.0001). Twenty four of 56 (43%) women with diagnosis of LSIL, and 2 (40%) of 5 with diagnosis of HSIL were positive for HPV infection. A statistically significant difference was found when we compared HPV infection in negative Pap smears and those with LSIL (p < 0.001). The present study found that the prevalence of HPV infection in asymptomatic Venezuelan women who attended a tertiary level hospital was 15.6%. HPV infection was more frequent in young adult, and in women with low educational level.

  2. Physical properties and characterizations of Venezuelan heavy and extraheavy crudes and bitumens

    SciTech Connect

    Guzman, C.; Montero, C.; Briceno, M.; Chirinos, M.; Layrisse, I.

    1988-06-01

    The largest heavy (10 to 20/sup 0/ A PI) and extraheavy (<10/sup 0/ A PI) crude oil and bitumen reservoirs are located in Venezuela, in the Orinoco Belt (OB) and the Maracaibo Basin (MB). These represent most of the Venezuelan petroleum resources and, as a consequence, there is great interest in the development of a convenient technology for the handling, transportation and treatment of the OB and MB crude oils and bitumens. Hence, a knowledge of their physical properties is required for the purpose of equipment and instrument design, as well as for the prediction of their behavior at the treatment stage. At present, little, if any, data is available for these oils despite a few attempts to evaluate and correlate their physical properties. Others have brought about a rheological characterization of the OB crude oils and bitumens, and proposed several correlations for the prediction of the density and kinematic viscosity. These equations are discussed in this paper. In this work, an all-encompassing evaluation of the Venezuelan heavy and extraheavy crude oils and bitumens is presented. Since the latter may be produced in various forms (e.g., dilution mixing of different wells outputs), representative samples of mixtures of crude oils and dilutions have been prepared for their physical characterization. Several of the most used properties in the handling of these oils have been evaluated, namely, density, viscosity, thermal conductivity, specific heat and vapor pressure. To that end, adaptions of commercial measurement techniques as well as new developments were performed. In addition, an attempt to obtain functional relations for the prediction of these properties were performed. In addition, an attempt to obtain functional relations for the prediction of these properties was carried out.

  3. Permafrost distribution modelling in the semi-arid Chilean Andes

    NASA Astrophysics Data System (ADS)

    Azócar, Guillermo F.; Brenning, Alexander; Bodin, Xavier

    2017-04-01

    Mountain permafrost and rock glaciers in the dry Andes are of growing interest due to the increase in mining industry and infrastructure development in this remote area. Empirical models of mountain permafrost distribution based on rock glacier activity status and temperature data have been established as a tool for regional-scale assessments of its distribution; this kind of model approach has never been applied for a large portion of the Andes. In the present study, this methodology is applied to map permafrost favourability throughout the semi-arid Andes of central Chile (29-32° S), excluding areas of exposed bedrock. After spatially modelling of the mean annual air temperature distribution from scarce temperature records (116 station years) using a linear mixed-effects model, a generalized additive model was built to model the activity status of 3524 rock glaciers. A permafrost favourability index (PFI) was obtained by adjusting model predictions for conceptual differences between permafrost and rock glacier distribution. The results indicate that the model has an acceptable performance (median AUROC: 0.76). Conditions highly favourable to permafrost presence (PFI ≥ 0.75) are predicted for 1051 km2 of mountain terrain, or 2.7 % of the total area of the watersheds studied. Favourable conditions are expected to occur in 2636 km2, or 6.8 % of the area. Substantial portions of the Elqui and Huasco watersheds are considered to be favourable for permafrost presence (11.8 % each), while in the Limarí and Choapa watersheds permafrost is expected to be mostly limited to specific sub-watersheds. In the future, local ground-truth observations will be required to confirm permafrost presence in favourable areas and to monitor permafrost evolution under the influence of climate change.

  4. 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.

  5. 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.

  6. 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.

  7. Autosomal microsatellite data from Northwestern Colombia.

    PubMed

    Palacio, Oscar Darío; Triana, Omar; Gaviria, Aníbal; Ibarra, Adriana Alexandra; Ochoa, Luz Mariela; Posada, Yeny; Maya, María Clara; Lareu, María Victoria; Brión, María; Acosta, María Amparo; Carracedo, Angel

    2006-07-13

    Allele frequencies and some forensic parameters for 12 autosomal microsatellites (CSF1PO, TPOX, THO1, VWA, D16S539, D7S820, D13S317, D5S818, F13A1, FESFPS, F13B, LPL) were estimated from three departments from Northwestern Colombia. The total number of samples analysed was 1045 individuals. Comparative analysis among the three studied departments and with other published Colombian populations were also performed and discussed.

  8. Peralkaline silicic volcanic rocks in northwestern nevada.

    PubMed

    Noble, D C; Chipman, D W; Giles, D L

    1968-06-21

    Late Tertiary silicic ashflow tuffs and lavas peralkaline in chemical character (atomic Na + K greater than Al), mainly comendites, occur over wide areas in northwestern Nevada and appear to be widespread in southeastern Oregon. Such peralkaline rocks-which are not uncommon in the western United States-and other chemically unusual silicic rocks are found near the margins rather than toward the center of the Great Basin.

  9. Wood Energy Potential in Northwestern South Carolina

    Treesearch

    James W. McMinn

    1986-01-01

    The quantity of unused wood in an Ill-county area in northwestern South Carolina was projected to be more than 16 million tons annually. Wood that is unsuitable for products other than fuel amounts to nearly 9 million tons annually.The most likely energy demand by industrial plants that are good candidates for wood fuel systems is 1.5 million tons annually.Maximum...

  10. 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.

  11. Demography of Dall's sheep in northwestern Alaska

    USGS Publications Warehouse

    Kleckner, Christopher; Udevitz, Mark S.; Adams, Layne G.; Shults, Brad S.

    2003-01-01

    Dall’s sheep in northwestern Alaska declined in the early 1990s following the severe 1989-90 and 1990-91 winters. In the Baird Mountains of Noatak National Preserve, estimates of adult sheep declined by 50% from 800 in 1989 to under 400 in 1991. Population counts remained low throughout 1991 to 1996, reaching a minimum of 244 adult sheep in 1996. Few lambs were observed during annual midsummer aerial surveys in 1991 to 1994. We suspect that these declines resulted from a combination of poorer nutritional condition and increased vulnerability of sheep to predation resulting from severe winter conditions.As a result of these declines, both subsistence and sport hunting seasons were closed by emergency order in 1991, resulting in substantial management controversy. The affected publics, although willing to accept the closures, questioned the validity of the sheep survey data and strongly emphasized their interest in restoring harvests as soon as populations increased sufficiently. In 1995 the Northwest Arctic Regional Advisory Council, the local advisory committee for the Federal Subsistence Board, passed a motion supporting efforts to initiate research on sheep populations in the region to better understand the factors limiting sheep populations and to evaluate sheep survey methodologies.Currently estimates of Dall’s sheep population size and composition in the western Brooks Range are based on intensive fixed-wing aerial surveys conducted annually since 1986 in areas including the Baird Mountains. The annual variation in recent Baird Mountains aerial counts cannot be explained with reasonable assumptions about reproduction and survival, suggesting that there is some variability in the proportion of the population observed each year or that a substantial number of sheep move during the survey. Prior to our research, no attempt had been made to estimate visibility bias or precision for these surveys.Our understanding of Dall’s sheep population biology comes

  12. IGG Subclass and Isotype Specific Immunoglobulin Responses to LASSA fever and Venezuelan Equine Encephalomyelitis: Natural Infection and Immunication

    DTIC Science & Technology

    1989-03-01

    VENEZUELAN EQUINE ENCEPHALOMYELITIS: NATURAL INFECTION AND IMMUNIZATION PRINCIPAL INVESTIGATOR: Renata J. Engler CONTRACTING ORGANIZATION: Uniformed Services...University of Health Sciences 4301 Jones Bridges Road Bethesda, MD 20814-4799 DTIC REPORT DATE: March 1, 1989 E T E MAR0 6 1990 TYPE OF REPORT...University (if applicable) of Health Sciences I 6c. ADDRESS (City, State, and ZIP Code) 7b. ADDRESS (City, State, and ZIP Code) 4301 Jones Bridges Road

  13. Monogenetic volcanism in the Cordillera Central of Colombia: unknown volcanic fields associated with the northernmost Andes' volcanic chain related subduction

    NASA Astrophysics Data System (ADS)

    Murcia, Hugo; Borrero, Carlos; Németh, Károly

    2017-04-01

    Monogenetic volcanic fields are commonly related to rifts and/or intraplate tectonic settings. However, although less common, they appear also associated with subduction zones, including both front and back-arc volcanoes. To nourish this uncommon tectonic location, it is shown here that monogenetic volcanic fields, in addition to polygenetic volcanoes, also appear at the northernmost part of the Andes Northern Volcanic Zone (NVZ) (2° S to 4°30´N). These fields are associated with the main axe of the Quaternary active volcanic structures; they are linked to the polygenetic Cerro Bravo - Cerro Machín Volcanic Chain ( 80 km long; CBCMVC) in Colombia, the chain that hosts the iconic Nevado del Ruiz volcano. To the present, three monogenetic volcanic fields, with a typical calc-alkaline signature, have been identified in both sides of this chain: 1) Villamaría - Termales Monogenetic Volcanic Field (VTMVF) located to the northwestern part (>5 km) of the CBCMVC. This field is made up of at least 14 volcanoes aligned with the Villamaría - Termales fault zone. The volcanism has been mainly effusive, represented by lava domes and some lava flows. The volcanoes are andesitic to dacitic in composition. It is inferred that the magmatic source is a magma chamber close to Nevado del Ruiz volcano. Based on stratigraphic relationships, it is assumed that the last eruption occurred <38 ka. 2) Samaná Monogenetic Volcanic Field (SMVF) located 50 km north of Romeral volcano, the northernmost active volcano from the CBCMVC. This field comprises at least three volcanoes: A maar-diatreme volcano ( 20 ka years old) and two undefined structures. The volcanic products exhibit andesitic and riolitic composition. It is inferred that this field results of the same magmatism of the CBCMVC. 3. Pijaos Monogenetic Volcanic Field (PMVF) located 25 km south of Cerro Machín volcano, the southernmost active volcano of the CBCMVC. This field comprises at least four volcanoes formed by effusive

  14. Dynamics of mountain building: case study Central Andes (Peru)

    NASA Astrophysics Data System (ADS)

    Gonzalez, Laura; Pfiffner, O. Adrian

    2010-05-01

    We present the structural style and ist extrapolation to depth in a transect through the Central Andes of Peru from the Pacific Ocean to the Amazon foreland. The Western Cordillera consists of a E-vergent fold-and-thrust belt in the Jurassic to Cretaceous strata that is intruded by various granites and granodiorites of the Coastal Batholith. A folded volcanic arc sequence (Casma group) straddles the western margin of the Western Cordillera. Eocene to Oligocene volcanics of the Calipuy group were deposited within the cordillera after an erosional event and became subsequently slightly tilted and folded. Owing to a shallower dip of the subduction zone, volcanism ceased in Miocene times. The Eastern Cordillera has a core made up of a Late Paleozoic orogen. To the east, E-vergent Neogene thrusting migrated towards the Amazon foreland and produced the fold-and-thrust belt of the Subandean Zone. Thrusts that penetrate deep into the crust are likely to be responsible for the high elevation of the present day Andes. To the west, steep reverse faults with strike slip component raise Neoproterozoic of the core of the Eastern Cordillera adjacent to unmetamorphosed Permian sediments. Deformed Pleistocene gravels and faulted Holocene gravels witness to the ongoing deformation within and between the two cordilleras.

  15. Radial anisotropy from ambient noise tomography in the Central Andes

    NASA Astrophysics Data System (ADS)

    Lynner, C.; Beck, S. L.; Zandt, G.; Ward, K. M.; Delph, J. R.; Porritt, R. W.; Long, M. D.; Wagner, L. S.

    2016-12-01

    There has been a great deal of work done in the Central Andes in Peru, Bolivia, Chile, and Argentina. The Central Andes are characterized by the largest orogenic plateau globally, areas with different styles of subduction, and regions of tremendous volcanism. One popular way of seismically imaging the region has been the use of ambient noise tomography (ANT). ANT studies use estimated Green's functions to determine Rayleigh wave dispersion curves. The dispersion curves are then used to constrain 3D shear velocity models. The vast majority of ANT studies use only Rayleigh waves to constrain their velocity models. By only using phase velocities from Rayleigh waves, instead of using both Rayleigh and Love waves, those studies lack the ability to constrain patterns of radial anisotropy. Measuring radial anisotropy in the Central Andean crust can help constrain patterns of crustal deformation (potentially lower crustal flow) and offer insights into ongoing magmatism. Here we present Vsh, Vsv, radial, and azimuthal anisotropy results from Love and Rayleigh ambient noise tomography.

  16. 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.

  17. Susceptibility of Psorophora confinnis (Diptera: Culicidae) to infection with epizootic (subtype IC) and enzootic (subtype ID) Venezuelan Equine encephalitis viruses.

    PubMed

    Ortiz, Diana I; Anishchenko, Michael; Weaver, Scott C

    2005-09-01

    To test the hypothesis that adaptation to epizootic mosquito vectors mediates the emergence of Venezuelan equine encephalitis virus (family Togaviridae, genus Alphavirus, VEEV) from enzootic progenitors, the susceptibility of the epizootic vector Psorophora confinnis (Lynch-Arribalzaga) to epizootic versus enzootic strains was evaluated. Artificial bloodmeals containing subtype IC strains isolated during the 1962-1964, 1992-1993, and 1995 Venezuelan/Colombian epizootics and closely related Venezuelan enzootic subtype ID strains were used to compare mosquito infectivity and transmission potential. Strains from the smaller 1992-1993 epizootic showed lower or equal infectivity and replication compared with enzootic viruses and to strains isolated during the larger 1962-1964 and 1995 epizootics. These experiments failed to provide evidence that Ps. confinnis selects for epizootic VEEV viruses with higher infectivity, as has been shown for Aedes (Ochlerotatus) taeniorhynchus (Wiedemann). Nonetheless, its high susceptibility, abundance in enzootic and epizootic regions, and feeding behavior suggest that Ps. confinnis is an important bridge vector for both enzootic and epizootic VEEV.

  18. [Do some conditions contribute to the reemergence of the Venezuelan equine encephalitis virus in the Colombian Alta Guajira?].

    PubMed

    Ferro, Cristina; De Las Salas, Jorge; González, Martha; Díaz, Alberto; Cabrera, Claudia; Flórez, Zulibeth; Duque, María Clara; Lugo, Ligia; Bello, Betsy

    2015-01-01

    In the last 18 years, epizootics of Venezuelan equine encephalitis have not occurred in places with historic epidemic register (1925-1995) in the Guajira Peninsula, Colombia. To assess if the Guajira Peninsula, Colombia, still maintains the epidemiological conditions for Venezuelan equine encephalitis virus reemergence. Research was carried out in places affected by the 1995 epidemic. We evaluated: 1) abundance and seasonal variation of vector mosquito populations; 2) availability of mammals that are potential amplifiers of the virus, and 3) knowledge among the community about the disease and its vectors. Most of the 16 mosquito species were found during the rainy season. Aedes taeniorhynchus and Psorophora confinnis showed direct relation with rainfall and temperature. In contrast, the dominant species, Deinocerites atlanticus , was always present in the collections, regardless of climatic conditions. No IgG antibodies were found in humans younger than 17 years old, goats or bovine sera. One third of those interviewed remembered the last epidemic and had basic understanding of the disease. Only 20% of the families were owners of equines, and 8% was informed of the importance of equine vaccination. Some epidemiological conditions that eventually could help epizootic Venezuelan equine encephalitis virus reemergence are maintained. However, an abrupt decrease in the number of susceptible equines was found in the area. Apparently, this new condition has not allowed the virus reemergence and is the biggest observed change.

  19. Andes Virus and First Case Report of Bermejo Virus Causing Fatal Pulmonary Syndrome

    PubMed Central

    Della Valle, Marcelo González; Alai, María Garcia; Cortada, Pedro; Villagra, Mario; Gianella, Alberto

    2002-01-01

    Two suspected hantavirus pulmonary syndrome (HPS) cases from Bolivia were confirmed by enzyme-linked immunosorbent assay. (ELISA)-ANDES was performed using N-Andes recombinant antigen serology in May and July 2000. Clot RNAs from the two patients were subjected to reverse transcription–polymerase chain reaction (PCR) amplification and sequencing. We describe two characterized cases of HPS. One was caused by infection with Bermejo virus and the other with Andes Nort viral lineage, both previously obtained from Oligoryzomys species. This is the first report of molecular identification of a human hantavirus associated with Bermejo virus. PMID:11971782

  20. Ablation of Programmed −1 Ribosomal Frameshifting in Venezuelan Equine Encephalitis Virus Results in Attenuated Neuropathogenicity

    PubMed Central

    Kendra, Joseph A.; de la Fuente, Cynthia; Brahms, Ashwini; Woodson, Caitlin; Bell, Todd M.; Chen, Bin; Khan, Yousuf A.; Jacobs, Jonathan L.

    2016-01-01

    ABSTRACT The alphaviruses Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV) are arthropod-borne positive-strand RNA viruses that are capable of causing acute and fatal encephalitis in many mammals, including humans. VEEV was weaponized during the Cold War and is recognized as a select agent. Currently, there are no FDA-approved vaccines or therapeutics for these viruses. The spread of VEEV and other members of this family due to climate change-mediated vector range expansion underscores the need for research aimed at developing medical countermeasures. These viruses utilize programmed −1 ribosomal frameshifting (−1 PRF) to synthesize the viral trans-frame (TF) protein, which has previously been shown to be important for neuropathogenesis in the related Sindbis virus. Here, the alphavirus −1 PRF signals were characterized, revealing novel −1 PRF stimulatory structures. −1 PRF attenuation mildly affected the kinetics of VEEV accumulation in cultured cells but strongly inhibited its pathogenesis in an aerosol infection mouse model. Importantly, the decreased viral titers in the brains of mice infected with the mutant virus suggest that the alphavirus TF protein is important for passage through the blood-brain barrier and/or for neuroinvasiveness. These findings suggest a novel approach to the development of safe and effective live attenuated vaccines directed against VEEV and perhaps other closely related −1 PRF-utilizing viruses. IMPORTANCE Venezuelan equine encephalitis virus (VEEV) is a select agent that has been weaponized. This arthropod-borne positive-strand RNA virus causes acute and fatal encephalitis in many mammals, including humans. There is no vaccine or other approved therapeutic. VEEV and related alphaviruses utilize programmed −1 ribosomal frameshifting (−1 PRF) to synthesize the viral trans-frame (TF) protein, which is important for neuropathogenesis. −1

  1. 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

  2. New records of mosquitoes from northwestern Argentina.

    PubMed

    Dantur Juri, María J; Stein, Marina; Rossi, Gustavo C; Navarro, Juan Carlos; Zaidenberg, Mario; Sallum, María A Mureb

    2012-06-01

    Eleven mosquito species, namely Aedes hastatus, Ae. fulvus, Coquillettidia albicosta, Cq. juxtamansonia, Culex aliciae, Cx. delpontei, Cx. oedipus, Cx. pedroi, Mansonia flaveola, Uranotaenia leucoptera, and Wyeomyia oblita, are recorded for the first time from northwestern Argentina. In addition, 3 species, Cx. brethesi, Limatus durhami, and Ur. nataliae, are reported for the first time from Salta Province. These records extend the geographical distribution of these 3 species to Salta Province. This study also extends the geographical distributions of Cq. nigricans, Cx. chidesteri, and Ma. humeralis to Jujuy Province and of Ae. meprai, Ae. milleri, Ae. oligopistus, Cx. brethesi, Cx. fernandezi, and Cx. tatoi to Tucumán Province.

  3. 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.

  4. GT-12 - EARTH SKY - NORTHWESTERN MEXICO

    NASA Image and Video Library

    1966-11-12

    S66-63440 (12 Nov. 1966) --- Area of northwestern Mexico as seen from the Gemini-12 spacecraft during its 16th revolution of Earth. View is looking northwest. Body of water in the foreground is the Gulf of California. Pacific Ocean is in the background. Peninsula in center of picture is Baja California. States of Sonora (upper right) and Sinaloa (lower center) of Mexican mainland is in right foreground. City of Guaymas, Sonora, is near the center of the picture. Photo credit: NASA

  5. Bankfull discharge and sediment transport in northwestern California

    Treesearch

    K. M. Nolan; T. E. Lisle; H. M. Kelsey

    1987-01-01

    Abstract - High-magnitude, low-frequency discharges are more responsible for transporting suspended sediment and forming channels in northwestern California than in previously studied areas. Bankfull discharge and the magnitude and frequency of suspended sediment discharge were determined at five gaging stations in northwestern California. Although discharges below...

  6. Modelling Andes Uplift Impact on Atmospheric Circulation: Consequences for Neogene Faunal and Floral Evolution ?

    NASA Astrophysics Data System (ADS)

    Sepulchre, P.; Sloan, L. C.; Fluteau, F.

    2007-12-01

    Tectonics in South America is marked by the uplift of the Andes during the Cenozoic. The Andes are approximately 7000 km long, oriented north-south, with some peak elevations in excess of 6000 m. Such a topographic structure has potentially a strong impact on atmospheric circulation. Climate model studies have showed that the Andes, as a topographic barrier, influence eastern Pacific Ocean climate and also meridional moisture transport above the south American continent. However, most studies have been done at the regional scale, and no quantification of rainfall changes due to a lower topography has been done. Here we use the high resolution Atmospheric General Circulation Model LMDz4 to quantify the impact of the Andes topography on the rainfall regime over the whole South American continent. Interpreting sensitivity experiments, we discuss about the tectonics history from 55 Ma to present-day and how to apply this method for Neogene paleoclimate, in a different continental configuration.

  7. The last occurrence of Pleistocene megafauna in the Ecuadorian Andes

    NASA Astrophysics Data System (ADS)

    Coltorti, M.; Ficcarelli, G.; Jahren, H.; Espinosa, M. Moreno; Rook, L.; Torre, D.

    1998-12-01

    The latest Pleistocene—Holocene megafauna extinction is a global event, particularly dramatic in the Americas. In a previous paper the authors hypothesised a scenario for this extinction event in South America, where mastodonts first suffered from the changing climate environment, followed by the mylodonts and equids. These different latest Pleistocene—Holocene megafauna extinction "waves" in Ecuadorian Andes have been dated using 14C methods on material from selected sites in north and central Ecuadorian Interandean Depression. An outline of the physiographic evolution of the Interandean Depression in Ecuador is offered and the stratigraphic setting of the fossiliferous sites is discussed. The present results confirm the author's hypothesis on the megafauna extinction pattern, previously published in terms of relative age. The importance of climatic changes during Last Glacial Maximum at low latitudes is discussed.

  8. STS-31 Earth observation of the Andes Mountains

    NASA Image and Video Library

    1990-04-29

    STS031-83-090 (24-29 April 1990) --- This late afternoon scene over the Andes Mountains features sun glare, heavy cloud illumination and sunglint against the Pacific Ocean. This photo was among those selected by the crew members for showing at their May 9, 1990, Post-Flight Press Conference (PFPC) at the Johnson Space Center (JSC) Public Affairs Office (PAO) Facility briefing room. Onboard the Space Shuttle Discovery for the flight, which lifted off on April 24, 1990, and landed on April 29, 1990, were astronauts Loren J. Shriver, Charles F. Bolden, Jr., Bruce McCandless II, Kathryn D. Sullivan and Steven A. Hawley. Some of the slides were not actually shown due to a shortage of time.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Protoplanetary Disk Structure with Grain Evolution: The ANDES Model

    NASA Astrophysics Data System (ADS)

    Akimkin, V.; Zhukovska, S.; Wiebe, D.; Semenov, D.; Pavlyuchenkov, Ya.; Vasyunin, A.; Birnstiel, T.; Henning, Th.

    2013-03-01

    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 <~ 50 AU) and lower in the outer disk (R >~ 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., CO2, NH2CN, HNO, H2O, HCOOH, HCN, and CO. We also show that time-dependent chemistry is important for a proper description of gas thermal balance.

  14. ANDES: Statistical tools for the ANalyses of DEep Sequencing.

    PubMed

    Li, Kelvin; Venter, Eli; Yooseph, Shibu; Stockwell, Timothy B; Eckerle, Lance D; Denison, Mark R; Spiro, David J; Methé, Barbara A

    2010-07-15

    The advancements in DNA sequencing technologies have allowed researchers to progress from the analyses of a single organism towards the deep sequencing of a sample of organisms. With sufficient sequencing depth, it is now possible to detect subtle variations between members of the same species, or between mixed species with shared biomarkers, such as the 16S rRNA gene. However, traditional sequencing analyses of samples from largely homogeneous populations are often still based on multiple sequence alignments (MSA), where each sequence is placed along a separate row and similarities between aligned bases can be followed down each column. While this visual format is intuitive for a small set of aligned sequences, the representation quickly becomes cumbersome as sequencing depths cover loci hundreds or thousands of reads deep. We have developed ANDES, a software library and a suite of applications, written in Perl and R, for the statistical ANalyses of DEep Sequencing. The fundamental data structure underlying ANDES is the position profile, which contains the nucleotide distributions for each genomic position resultant from a multiple sequence alignment (MSA). Tools include the root mean square deviation (RMSD) plot, which allows for the visual comparison of multiple samples on a position-by-position basis, and the computation of base conversion frequencies (transition/transversion rates), variation (Shannon entropy), inter-sample clustering and visualization (dendrogram and multidimensional scaling (MDS) plot), threshold-driven consensus sequence generation and polymorphism detection, and the estimation of empirically determined sequencing quality values. As new sequencing technologies evolve, deep sequencing will become increasingly cost-efficient and the inter and intra-sample comparisons of largely homogeneous sequences will become more common. We have provided a software package and demonstrated its application on various empirically-derived datasets

  15. Biogeochemistry of a treeline watershed, northwestern Alaska.

    PubMed

    Stottlemyer, R

    2001-01-01

    Since 1950, mean annual temperatures in northwestern Alaska have increased. Change in forest floor and soil temperature or moisture could alter N mineralization rates, production of dissolved organic carbon (DOC) and organic nitrogen (DON), and their export to the aquatic ecosystem. In 1990, we began study of nutrient cycles in the 800-ha Asik watershed, located at treeline in the Noatak National Preserve, northwestern Alaska. This paper summarizes relationships between topographic aspect, soil temperature and moisture, inorganic and organic N pools, C pools, CO2 efflux, growing season net N mineralization rates, and stream water chemistry. Forest floor (O2) C/N ratios, C pools, temperature, and moisture were greater on south aspects. More rapid melt of the soil active layer (zone of annual freeze-thaw) and permafrost accounted for the higher moisture. The O2 C and N content were correlated with moisture, inorganic N pools, CO2 efflux, and inversely with temperature. Inorganic N pools were correlated with temperature and CO2 efflux. Net N mineralization rates were positive in early summer, and correlated with O2 moisture, temperature, and C and N pools. Net nitrification rates were inversely correlated with moisture, total C and N. The CO2 efflux increased with temperature and moisture, and was greater on south aspects. Stream ion concentrations declined and DOC increased with discharge. Stream inorganic nitrogen (DIN) output exceeded input by 70%. Alpine stream water nitrate (NO3-) and DOC concentrations indicated substantial contributions to the watershed DIN and DOC budgets.

  16. Biogeochemistry of a treeline watershed, northwestern Alaska

    USGS Publications Warehouse

    Stottlemyer, R.

    2001-01-01

    Since 1950, mean annual temperatures in northwestern Alaska have increased. Change in forest floor and soil temperature or moisture could alter N mineralization rates, production of dissolved organic carbon (DOC) and organic nitrogen (DON), and their export to the aquatic ecosystem. In 1990, we began study of nutrient cycles in the 800-ha Asik watershed, located at treeline in the Noatak National Preserve, northwestern Alaska. This paper summarizes relationships between topographic aspect, soil temperature and moisture, inorganic and organic N pools, C pools, CO2 efflux, growing season net N mineralization rates, and stream water chemistry. Forest floor (O2) C/N ratios, C pools, temperature, and moisture were greater on south aspects. More rapid melt of the soil active layer (zone of annual freeze-thaw) and permafrost accounted for the higher moisture. The O2 C and N content were correlated with moisture, inorganic N pools, CO2 efflux, and inversely with temperature. Inorganic N pools were correlated with temperature and CO2 efflux. Net N mineralization rates were positive in early summer, and correlated with O2 moisture, temperature, and C and N pools. Net nitrification rates were inversely correlated with moisture, total C and N. The CO2 efflux increased with temperature and moisture, and was greater on south aspects. Stream ion concentrations declined and DOC increased with discharge. Stream inorganic nitrogen (DIN) output exceeded input by 70%. Alpine stream water nitrate (NO-3) and DOC concentrations indicated substantial contributions to the watershed DIN and DOC budgets.

  17. Temporal Analysis of Andes Virus and Sin Nombre Virus Infections of Syrian Hamsters

    DTIC Science & Technology

    2007-05-01

    at later times (e.g., after disease onset). 15. SUBJECT TERMS hantavirus, Andes virus , sin nombre virus , pathogenesis , blood chemistry, hematology...to blood draw; SAC, no signs of disease when sacrificed; EUTH, moribund animal euthanized. VOL. 81, 2007 PATHOGENESIS OF ANDES VIRUS IN HAMSTERS 7451...additional research into the pathogenesis of and development of medical countermeasures to these highly lethal viruses . Hantaviruses represent a diverse group

  18. Harmonizing regulations for biomedical research: a critical analysis of the US and Venezuelan systems.

    PubMed

    Di Tillio-Gonzalez, Dannie; Fischbach, Ruth L

    2008-12-01

    This article aims to compare the national legal systems that regulate biomedical research in an industrialized country (United States) and a developing country (Venezuela). A new international order is emerging in which Europe, Japan and the United States (US) are revising common guidelines and harmonizing standards. In this article, we analyze - as an example - the US system. This system is controlled by a federal agency structured to regulate research funded by the federal government uniformly, either in the US or abroad. In contrast, in Venezuela, a developing country, the creation of a centralized system is a slow process. Different types of ethical committees review research projects using non-uniform criteria. Consequently, various parallel organizations that conduct biomedical research, such as universities, research institutes and private hospitals have diverse regulations operating at a local level. Thus, the most relevant difference between the Venezuelan and the US systems is the degree of standardization. In the US, the review process is performed by institutional review boards (IRBs), which have a similar organization and maintain relationships with a centralized agency, following standard regulations. Although new proposals for establishing national regulations are currently being considered in Venezuela, the success of these initiatives will depend on promoting governmental efforts to create a more structured centralized system supported by a national regulatory framework. This system will need governmental financial support at all levels. This article proposes an integrated system to regulate research with human participants in Venezuela and other developing countries.

  19. 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

  20. Potential Sympatric Vectors and Mammalian Hosts of Venezuelan Equine Encephalitis Virus in Southern Mexico.

    PubMed

    Sotomayor-Bonilla, Jesús; Abella-Medrano, Carlos Antonio; Chaves, Andrea; Álvarez-Mendizábal, Paulina; Rico-Chávez, Óscar; Ibáñez-Bernal, Sergio; Rostal, Melinda K; Ojeda-Flores, Rafael; Barbachano-Guerrero, Arturo; Gutiérrez-Espeleta, Gustavo; Aguirre, A Alonso; Daszak, Peter; Suzán, Gerardo

    2017-04-06

    Arboviruses are important zoonotic agents with complex transmission cycles and are not well understood because they may involve many vectors and hosts. We studied sympatric wild mammals and hematophagous mosquitoes having the potential to act as hosts and vectors in two areas of southern Mexico. Mosquitoes, bats, and rodents were captured in Calakmul (Campeche) and Montes Azules (Chiapas), between November 2010 and August 2011. Spleen samples from 146 bats and 14 rodents were tested for molecular evidence of Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), western equine encephalitis virus (WEEV), and West Nile virus (WNV) using PCR protocols. Bat ( Artibeus lituratus , Carollia sowelli , Glossophaga soricina , and Sturnira parvidens) and rodent ( Sigmodon hispidus and Oryzomys alfaroi ) species were positive for VEEV. No individuals were positive for WNV, EEEV, or WEEV. A total of 1,298 mosquitoes were collected at the same sites, and five of the mosquito species collected were known VEEV vectors (Aedes fulvus, Mansonia indubitans, Psorophora ferox, Psorophora cilipes, and Psorophora confinnis). This survey simultaneously presents the first molecular evidence, to our knowledge, of VEEV in bats and rodents from southern Mexico and the identification of potential sympatric vectors. Studies investigating sympatric nonhuman hosts, vectors, and arboviruses must be expanded to determine arboviral dynamics in complex systems in which outbreaks of emerging and reemerging zoonoses are continuously occurring.

  1. Noncytopathic Replication of Venezuelan Equine Encephalitis Virus and Eastern Equine Encephalitis Virus Replicons in Mammalian Cells

    PubMed Central

    Petrakova, Olga; Volkova, Eugenia; Gorchakov, Rodion; Paessler, Slobodan; Kinney, Richard M.; Frolov, Ilya

    2005-01-01

    Venezuelan equine encephalitis (VEE) and eastern equine encephalitis (EEE) viruses are important, naturally emerging zoonotic viruses. They are significant human and equine pathogens which still pose a serious public health threat. Both VEE and EEE cause chronic infection in mosquitoes and persistent or chronic infection in mosquito-derived cell lines. In contrast, vertebrate hosts infected with either virus develop an acute infection with high-titer viremia and encephalitis, followed by host death or virus clearance by the immune system. Accordingly, EEE and VEE infection in vertebrate cell lines is highly cytopathic. To further understand the pathogenesis of alphaviruses on molecular and cellular levels, we designed EEE- and VEE-based replicons and investigated their replication and their ability to generate cytopathic effect (CPE) and to interfere with other viral infections. VEE and EEE replicons appeared to be less cytopathic than Sindbis virus-based constructs that we designed in our previous research and readily established persistent replication in BHK-21 cells. VEE replicons required additional mutations in the 5′ untranslated region and nsP2 or nsP3 genes to further reduce cytopathicity and to become capable of persisting in cells with no defects in alpha/beta interferon production or signaling. The results indicated that alphaviruses strongly differ in virus-host cell interactions, and the ability to cause CPE in tissue culture does not necessarily correlate with pathogenesis and strongly depends on the sequence of viral nonstructural proteins. PMID:15919912

  2. 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.

  3. 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

  4. 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.

  5. Early response to the effect of iron fortification in the Venezuelan population.

    PubMed

    Layrisse, M; Chaves, J F; Mendez-Castellano; Bosch, V; Tropper, E; Bastardo, B; González, E

    1996-12-01

    In Venezuela a severe economic crisis beginning in 1983 provoked a progressive reduction of the quality and quantity of food consumed by the low socioeconomic strata of the population. In these strata, which represent > or = 80% of the Venezuelan population, we had seen a continuous increase in the prevalence of iron deficiency during that recent decade. As a result, in 1993 the Venezuela Government created the Special Commission for Enrichment of Foods. That same year a fortification program began in which precooked yellow and white maize and wheat flours were enriched with 20 and 50 mg Fe (as ferrous fumarate)/kg flour, respectively. The corn flour was also enriched with vitamin A, thiamine, riboflavin, and niacin, whereas the wheat flour was enriched with these same vitamins, except vitamin A. These two cereals represent 45% of the total energy consumed daily by the low socioeconomic strata of the population. A preliminary survey carried out in Caracas in 1994 in a population of 307 children aged 7, 11, and 15 y showed that the prevalence of iron deficiency determined by measuring the serum ferritin concentration and the prevalence of anemia were reduced from 37% and 19%, respectively, in 1992 to 15% and 10%, respectively in 1994.

  6. 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.

  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. Hydrocarbon-induced magnetic contrasts in some Venezuelan and Colombian oil wells

    NASA Astrophysics Data System (ADS)

    Costanzo-Alvarez, Vincenzo; Aldana, Milagrosa; Díaz, Marisel; Bayona, Germán; Ayala, Carolina

    2006-10-01

    In this work we present a review of our current research on the subject of near-surface hydrocarbon-induced magnetic contrasts. Samples are drill cuttings from number of Venezuelan and Colombian oil fields, and some soils from an oil prospective area. Results from rock magnetic, electronic paramagnetic resonance (EPR), extractable organic matter (EOM) and scanning electron microscopy (SEM) are discussed in light of new experiments. Two types of magnetic susceptibility (MS) anomalies have been recognized in oil well samples (i.e. A and B-like). A-like anomalies are probably associated to a reducing environment caused by the underlying reservoirs, whereas B-like anomalies might reflect lithological contrasts. Samples from A-like anomalous levels reveal the restrictive presence of authigenic spherical aggregates of submicronic Fe-rich magnetic crystals. Peaks of organic matter free radical concentration (OMFRC) and EOM are also observed at depth levels that lie close to those with A-like anomalies. Hysteresis ratios J rs/Js and H cr/Hc could be used as additional criteria to recognize A-like magnetic contrasts. In soil samples, MS and OMFRC anomalies coincide with peaks of ethane concentration and an area underneath where source rock has reached appropriate conditions of pressure and temperature to generate hydrocarbons (Cretaceous kitchen). Different types of crude oils and subsurface structures could have also a direct effect on the observed amplitude of A-like anomalies.

  9. Evolution and spread of Venezuelan equine encephalitis complex alphavirus in the Americas

    PubMed Central

    Dugan, Vivian G.; Auguste, Albert J.; Lin, David; Adams, A. Paige; Chen, Rubing; Gorchakov, Rodion; Leal, Grace; Estrada-Franco, Jose G.; Pandya, Jyotsna; Halpin, Rebecca A.; Hari, Kumar; Jain, Ravi; Stockwell, Timothy B.; Das, Suman R.; Wentworth, David E.; Smith, Martin D.; Kosakovsky Pond, Sergei L.; Weaver, Scott C.

    2017-01-01

    Venezuelan equine encephalitis (VEE) complex alphaviruses are important re-emerging arboviruses that cause life-threatening disease in equids during epizootics as well as spillover human infections. We conducted a comprehensive analysis of VEE complex alphaviruses by sequencing the genomes of 94 strains and performing phylogenetic analyses of 130 isolates using complete open reading frames for the nonstructural and structural polyproteins. Our analyses confirmed purifying selection as a major mechanism influencing the evolution of these viruses as well as a confounding factor in molecular clock dating of ancestors. Times to most recent common ancestors (tMRCAs) could be robustly estimated only for the more recently diverged subtypes; the tMRCA of the ID/IAB/IC/II and IE clades of VEE virus (VEEV) were estimated at ca. 149–973 years ago. Evolution of the IE subtype has been characterized by a significant evolutionary shift from the rest of the VEEV complex, with an increase in structural protein substitutions that are unique to this group, possibly reflecting adaptation to its unique enzootic mosquito vector Culex (Melanoconion) taeniopus. Our inferred tree topologies suggest that VEEV is maintained primarily in situ, with only occasional spread to neighboring countries, probably reflecting the limited mobility of rodent hosts and mosquito vectors. PMID:28771475

  10. Comparisons of Venezuelan encephalitis virus strains by hemagglutination-inhibition tests with chicken antibodies.

    PubMed Central

    Scherer, W F; Pancake, B A

    1977-01-01

    Twenty strains of Venezuelan encephalitis (VE) virus inoculated intravenously in large doses into roosters produced hemagglutination-inhibition (HI) antibodies detectable in plasmas within 7 to 10 days. No signs of illness occurred, and there was no evidence of viral growth in tissues since blood concentrations of infectious virus steadily decreased after inoculation. HI antibodies in early plasmas were specific for VE virus and did not cross-react significantly with two other North American alphaviruses, eastern and western encephalitis viruses. VE virus strains could be distinquished by virus-dilution, short-incubation HI, but not by plasma-dilution neutralization tests, by using early rooster antibodies. The distinctions by HI test were similar with some strains to, but different with other strains from, those described by Young and Johnson with the spiny rat antisera used to establish their subtype classifications of VE virus (14, 28). Nevertheless, results of HI tests with rooster antibodies correlated with equine virulence, as did results with spiny rat antibodies, and distinguished the new strains of virus that appeared in Middle America during the VE outbreak of 1969 from preexisting strains. PMID:591629

  11. Use of solid fuel in the production of pellets with Venezuelan iron ore

    SciTech Connect

    Rodriguez, A.; Ionescu, D.; Reyes, N.; Carrasquel, A.; Murati, C.; Guzman, J.L. )

    1993-01-01

    The pellet plant of Sidor consists of a dry grinding process for the iron ore and an induration process which takes place in a travelling grate furnace. The technical personnel considered the necessity of increasing the actual levels of productivity of 417 t/h and the abrasion index of 6%. To obtain this target, the technicians developed a series of pilot tests using solid fuel in the pelletizing mixture which gave positive results in the production of fluxed pellets using Venezuelan hematitic ore. At the industrial level the results were more successful than at pilot level; the productivity and the quality of pellets improved above the design values. The amount of coke used in the mixture was 0.7% and it required a significant change in the thermal profile of the furnace. The productivity increased 22.5% the abrasion index improved by 17.0%. The energy consumption was reduced to 25%. After this successful campaign there are plans for increasing the coke addition more than 1% which will allow abrasion levels between 4.0 and 4.5%, the compression strength between 320 and 330 Kg/pellet and also increase the productivity of the plant.

  12. [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.

  13. Histopathology and Distribution of Viral Antigens in Hamsters Infected with Virulent and Benign Venezuelan Encephalitis Viruses

    PubMed Central

    Jahrling, P. B.; Scherer, W. F.

    1973-01-01

    Lethalities and virulences of Venezuelan encephalitis (VE) viruses for hamsters were found to correlate with severity of histopathologic lesions in hematopoietic and brain tissues. Highly virulent strains (subtype I) destroyed marrow and lymphoid cells rapidly and produced intestinal wall damage; focal brain hemorrhages and destruction of Purkinje cells also occurred within the 4 to 5 days between subcutaneous inoculation and death. Like subtype I virus, a slightly less virulent strain (subtype II) also caused necrosis of bone marrow and brain lesions, but only minimal lymphoid cell damage occurred. The less virulent subtype III VE virus, which killed hamsters between 4 and 14 days after inoculation, usually caused no lesions in hematopoietic tissues, and deaths were related chiefly to hemorrhagic brain lesions and necrosis of Purkinje cells. Two VE viruses, benign for hamsters (the TC-83 attenuated vaccine strain and subtype IV), usually caused no necrosis of hematopoietic or brain tissues; focal extravasations of blood and swollen glial cells were found in brains of the rare hamsters that died. The degrees of necrosis seen in tissues stained with hematoxylin and eosin correlated with the quantities of viral antigens detected by fluorescent antibody, except in pancreas and small intestinal smooth muscle and glands, where antigens of subtype I virus were present without morphologic damage. ImagesFig 5-6Fig 7-8Fig 9Fig 10Fig 11Fig 12Fig 13Fig 14Fig 15Fig 16Fig 1-4 PMID:4578265

  14. Ablation of Programmed -1 Ribosomal Frameshifting in Venezuelan Equine Encephalitis Virus Results in Attenuated Neuropathogenicity.

    PubMed

    Kendra, Joseph A; de la Fuente, Cynthia; Brahms, Ashwini; Woodson, Caitlin; Bell, Todd M; Chen, Bin; Khan, Yousuf A; Jacobs, Jonathan L; Kehn-Hall, Kylene; Dinman, Jonathan D

    2017-02-01

    The alphaviruses Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV) are arthropod-borne positive-strand RNA viruses that are capable of causing acute and fatal encephalitis in many mammals, including humans. VEEV was weaponized during the Cold War and is recognized as a select agent. Currently, there are no FDA-approved vaccines or therapeutics for these viruses. The spread of VEEV and other members of this family due to climate change-mediated vector range expansion underscores the need for research aimed at developing medical countermeasures. These viruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which has previously been shown to be important for neuropathogenesis in the related Sindbis virus. Here, the alphavirus -1 PRF signals were characterized, revealing novel -1 PRF stimulatory structures. -1 PRF attenuation mildly affected the kinetics of VEEV accumulation in cultured cells but strongly inhibited its pathogenesis in an aerosol infection mouse model. Importantly, the decreased viral titers in the brains of mice infected with the mutant virus suggest that the alphavirus TF protein is important for passage through the blood-brain barrier and/or for neuroinvasiveness. These findings suggest a novel approach to the development of safe and effective live attenuated vaccines directed against VEEV and perhaps other closely related -1 PRF-utilizing viruses.

  15. Genetic and anatomic determinants of enzootic Venezuelan equine encephalitis virus infection of Culex (Melanoconion) taeniopus.

    PubMed

    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.

  16. Experimental Infection of Horses with an Attenuated Venezuelan Equine Encephalomyelitis Vaccine (Strain TC-83)

    PubMed Central

    Walton, Thomas E.; Alvarez, Otto; Buckwalter, Ross M.; Johnson, Karl M.

    1972-01-01

    Ten horses (Equus caballus) were vaccinated with strain TC-83 Venezuelan equine encephalomyelitis (VEE) virus vaccine. Febrile responses and leukopenia due to a reduction of lymphocytes and neutrophils were observed in all animals. Viremias were demonstrable in eight horses, with a maximum of 103.5 median tissue culture infectious dose units per ml of serum in two horses. Clinical illness with depression and anorexia were observed in five horses. Neutralizing (N), hemagglutination-inhibiting, and complement-fixing antibodies to the vaccine virus were demonstrable by 5, 6.5, and 7 days, respectively, after vaccination. Differential titrations of serum to six VEE strains revealed high titers of N antibody to vaccine virus, moderate titers to the epizootic Trinidad donkey no. 1 strain (VEE antigenic subtype I, variant A) from which TC-83 was derived, and low titers to two other epizootic strains (subtype I, variants B and C) in all horses at 1 month after vaccination; some animals responded with low levels of N antibody to the enzootic viruses (subtype I, variants D and E). Fourteen months after vaccination, six animals with detectable N antibody were challenged with MF-8 (subtype I, variant B), an epidemic-epizootic strain isolated in 1969 from a man in Honduras. All horses resisted challenge with the equine pathogenic strain of VEE. Marked increases of N antibody in most horses were demonstrable to some VEE strains when tested 1 month after challenge. PMID:4637604

  17. Characterization of Venezuelan vacuum residua and product vacuum residua obtained using the HDM{trademark} technology

    SciTech Connect

    Izquierdo, A.; Espidel, Y.; Fraile, R.

    1995-12-31

    Detailed characterization of heavy crudes and vacuum residua, as well as the resulting products of the necessary upgrading process, are of great importance in the use of these energy sources. The physical and chemical properties vary among different feedstocks and they determine different behavior during the upgrading process. This paper describes the characterization of five Venezuelan vacuum residua, 500{degrees}C+, and the vacuum residua of the products obtained when they were processed using the HDH{trademark} technology. The operating conditions were kept constant in order to be able to compare the reactivity of the different feedstocks. Special emphasis is given to the asphaltenes characterization and, in particular, to the results room the Average Molecular Parameters obtained by proton NMR. A correlation between these parameters and the reactivity was found. It was equally found that the asphaltenes of the feeds were very different in aromaticity, number of bridging aromatic carbons, and other properties involving the aromatic portion of these samples, whereas the asphaltenes of the resulting products had strong similarities. This indicates that despite the different nature o the starting material, the transformations during the process bring the high molecular weight aromatic components to similar structures.

  18. High prevalence of secondary resistance mutations in Venezuelan HIV-1 isolates.

    PubMed

    Dieudonne, Mariacarolina; Garzaro, Domingo; Torres, Jaime; Naranjo, Laura; Suárez, José Antonio; Castro, Julio; Martínez, Nahir; Castro, Erika; Berrueta, Lisbeth; Salmen, Siham; Devesa, Marisol; Rangel, Héctor R; Pujol, Flor Helene

    2006-03-01

    The genetic variability was studied in HIV-1 from Venezuelan patients with and without treatment, in order to evaluate the presence of polymorphisms and drug resistance mutations. Proviral DNA from peripheral blood mononuclear cells or viral RNA from plasma was extracted from the blood of 30 patients. Two regions from the polymerase gene, protease (Pr) and reverse transcriptase (RT) and one genomic fragment from the envelope (Env) gene were amplified and sequenced. All HIV-1 samples analyzed were classified as subtype B, without evidence of recombination. Although no primary protease mutations were detected, a high frequency of secondary mutations (86%, 19/22), associated to restoration of viral replicative fitness, was observed in strains circulating both in treated and non-treated patients. Resistance mutations to nucleoside RT inhibitors (NRTI) and non-nucleoside RT inhibitors (NNRTI) were detected in 35% (6/17) and 12% (2/17) of the viruses circulating in treated patients, respectively. Resistance mutations were also present in the virus infecting one antiretroviral naive individual (7.7%), suggesting that local screening for resistant mutation in naive patient might be important to minimize therapy failure. Future studies are warranted to assess the role of secondary mutation in the success of viral infection.

  19. Analysis of Venezuelan equine encephalitis replicon particles packaged in different coats.

    PubMed

    Kamrud, Kurt I; Alterson, Kim D; Andrews, Chasity; Copp, Laura O; Lewis, Whitney C; Hubby, Bolyn; Patel, Deepa; Rayner, Jonathan O; Talarico, Todd; Smith, Jonathan F

    2008-07-16

    The Venezuelan equine encephalitis (VEE) virus replicon system was used to produce virus-like replicon particles (VRP) packaged with a number of different VEE-derived glycoprotein (GP) coats. The GP coat is believed to be responsible for the cellular tropism noted for VRP and it is possible that different VEE GP coats may have different affinities for cells. We examined VRP packaged in four different VEE GP coats for their ability to infect cells in vitro and to induce both humoral and cellular immune responses in vivo. The VRP preparations were characterized to determine both infectious units (IU) and genome equivalents (GE) prior to in vivo analysis. VRP packaged with different VEE GP coats demonstrated widely varying GE/IU ratios based on Vero cell infectivity. BALB/c mice were immunized with the different VRP based on equal GE titers and the humoral and cellular responses to the expressed HIV gag gene measured. The magnitude of the immune responses measured in mice revealed small but significant differences between different GP coats when immunization was based on GE titers. We suggest that care should be taken when alternative coat proteins are used to package vector-based systems as the titers determined by cell culture infection may not represent accurate particle numbers and in turn may not accurately represent actual in vivo dose.

  20. [Venezuelan equine encephalitis. Determination of antibodies in the human population of Municipio Mirand, Estado Zulia, Venezuela].

    PubMed

    Ryder, S; Núñez-Camargo, J; Rangel, P; Añez, F

    1993-01-01

    With the purpose of determining antibodies prevalence against Venezuelan Equine Encephalitis Virus in the population of Puertos de Altagracia and Sabaneta de Palmas of Miranda county, Zulia State, Venezuela, 199 subjects were studied: 57 from Puertos de Altagracia and 142 from Sabaneta de Palmas. They were classified in older (42.78%) and younger (57.2%) than 15 years. The blood specimens were processed for Hemagglutination Inhibition Test using EEV antigen Goajira strain at pH 6.5. We found that all 57 specimens from Puertos de Altagracia were negative, whereas of 142 specimens from Sabaneta de Palmas 17 were positive (11.97%). Of these, one was from a subject less than 15 years-old (5.85%) and 16 from individuals more than 15 years-old (94.15%). Positive titers were higher than 1:160 in 80% of cases. Being Sabaneta de Palmas one of the most affected areas in the 1962 epidemic in the Miranda county and keeping the affected ones high positivity with elevated titers, we conclude that this population could represent an enzootic zone similar to Paez county where a similar situation, of high positivity and elevated titers, many years after the last epidemic occurred in that area, has been described.

  1. The Role of Venezuelan Space Technology in Promoting Development in Latin America

    NASA Astrophysics Data System (ADS)

    Pena, J. A.; Yumin, T.

    2017-09-01

    Space technology and resources are used around the world to address societal challenges. Space provides valuable satellite services, unique scientific discoveries, surprising technology applications and new economic opportunities. Venezuela formally recognizes the advantages of space resources and pursues national level activity to harness them. Venezuela space cooperation has grown in the past several years, contributing to debates over Venezuela's rising influence in the Latin America. This paper summarizes the establishment and current development of space activities in the Bolivarian Republic of Venezuela, these activities are focused on the areas of telecommunications, Earth observation, research and development space and has as a primary goal the satisfaction of social needs. This analysis offers the elements most important of the Venezuelan space policy: technological transfer, capacity building and human training and international cooperation including the new participation of Venezuela in the international charter on space and major disasters. Our analysis shows that Venezuela has the potential to become a space leadership country, promoting the social welfare, integration, and sustainable development of Latin American countries.

  2. Venezuelan Equine Encephalitis Viruses (VEEV) in Argentina: Serological Evidence of Human Infection

    PubMed Central

    Pisano, María Belén; Oria, Griselda; Beskow, Geraldine; Aguilar, Javier; Konigheim, Brenda; Cacace, María Luisa; Aguirre, Luis; Stein, Marina; Contigiani, Marta Silvia

    2013-01-01

    Venezuelan equine encephalitis viruses (VEEV) are responsible for human diseases in the Americas, producing severe or mild illness with symptoms indistinguishable from dengue and other arboviral diseases. For this reason, many cases remain without certain diagnosis. Seroprevalence studies for VEEV subtypes IAB, ID, IF (Mosso das Pedras virus; MDPV), IV (Pixuna virus; PIXV) and VI (Rio Negro virus; RNV) were conducted in persons from Northern provinces of Argentina: Salta, Chaco and Corrientes, using plaque reduction neutralization test (PRNT). RNV was detected in all studied provinces. Chaco presented the highest prevalence of this virus (14.1%). Antibodies against VEEV IAB and -for the first time- against MDPV and PIXV were also detected in Chaco province. In Corrientes, seroprevalence against RNV was 1.3% in the pediatric population, indicating recent infections. In Salta, this was the first investigation of VEEV members, and antibodies against RNV and PIXV were detected. These results provide evidence of circulation of many VEE viruses in Northern Argentina, showing that surveillance of these infectious agents should be intensified. PMID:24349588

  3. Isolation and Phylogenetic Analysis of Mucambo Virus (Venezuelan Equine Encephalitis Complex Subtype IIIA) in Trinidad

    PubMed Central

    Auguste, Albert J.; Volk, Sara M.; Arrigo, Nicole C.; Martinez, Raymond; Ramkissoon, Vernie; Adams, A. Paige; Thompson, Nadin N.; Adesiyun, Abiodun A.; Chadee, Dave D.; Foster, Jerome E.; Travassos Da Rosa, Amelia P.A.; Tesh, Robert B.; Weaver, Scott C.; Carrington, Christine V. F.

    2009-01-01

    In the 1950s and 1960s, alphaviruses in the Venezuelan equine encephalitis (VEE) antigenic complex were the most frequently isolated arboviruses in Trinidad. Since then, there has been very little research performed with these viruses. Herein, we report on the isolation, sequencing, and phylogenetic analyses of Mucambo virus (MUCV; VEE complex subtype IIIA), including 6 recently isolated from Culex (Melanoconion) portesi mosquitoes and 11 previously isolated in Trinidad and Brazil. Results show that nucleotide and amino acid identities across the complete structural polyprotein for the MUCV isolates were 96.6 – 100% and 98.7 – 100%, respectively, and the phylogenetic tree inferred for MUCV was highly geographically- and temporally- structured. Bayesian analyses suggest the sampled MUCV lineages have a recent common ancestry of approximately 198 years (with a 95% highest posterior density (HPD) interval of 63 – 448 years) prior to 2007, and an overall rate of evolution of 1.28 × 10−4 substitutions/site/yr. PMID:19631956

  4. Evolution and spread of Venezuelan equine encephalitis complex alphavirus in the Americas.

    PubMed

    Forrester, Naomi L; Wertheim, Joel O; Dugan, Vivian G; Auguste, Albert J; Lin, David; Adams, A Paige; Chen, Rubing; Gorchakov, Rodion; Leal, Grace; Estrada-Franco, Jose G; Pandya, Jyotsna; Halpin, Rebecca A; Hari, Kumar; Jain, Ravi; Stockwell, Timothy B; Das, Suman R; Wentworth, David E; Smith, Martin D; Kosakovsky Pond, Sergei L; Weaver, Scott C

    2017-08-01

    Venezuelan equine encephalitis (VEE) complex alphaviruses are important re-emerging arboviruses that cause life-threatening disease in equids during epizootics as well as spillover human infections. We conducted a comprehensive analysis of VEE complex alphaviruses by sequencing the genomes of 94 strains and performing phylogenetic analyses of 130 isolates using complete open reading frames for the nonstructural and structural polyproteins. Our analyses confirmed purifying selection as a major mechanism influencing the evolution of these viruses as well as a confounding factor in molecular clock dating of ancestors. Times to most recent common ancestors (tMRCAs) could be robustly estimated only for the more recently diverged subtypes; the tMRCA of the ID/IAB/IC/II and IE clades of VEE virus (VEEV) were estimated at ca. 149-973 years ago. Evolution of the IE subtype has been characterized by a significant evolutionary shift from the rest of the VEEV complex, with an increase in structural protein substitutions that are unique to this group, possibly reflecting adaptation to its unique enzootic mosquito vector Culex (Melanoconion) taeniopus. Our inferred tree topologies suggest that VEEV is maintained primarily in situ, with only occasional spread to neighboring countries, probably reflecting the limited mobility of rodent hosts and mosquito vectors.

  5. Molecular profiles of Venezuelan isolates of Trypanosoma sp. by random amplified polymorphic DNA method.

    PubMed

    Perrone, T M; Gonzatti, M I; Villamizar, G; Escalante, A; Aso, P M

    2009-05-12

    Nine Trypanosoma sp. Venezuelan isolates, initially presumed to be T. evansi, were collected from three different hosts, capybara (Apure state), horse (Apure state) and donkey (Guarico state) and compared by the random amplification polymorphic DNA technique (RAPD). Thirty-one to 46 reproducible fragments were obtained with 12 of the 40 primers that were used. Most of the primers detected molecular profiles with few polymorphisms between the seven horse, capybara and donkey isolates. Quantitative analyses of the RAPD profiles of these isolates revealed a high degree of genetic conservation with similarity coefficients between 85.7% and 98.5%. Ten of the primers generated polymorphic RAPD profiles with two of the three Trypanosoma sp. horse isolates, namely TeAp-N/D1 and TeGu-N/D1. The similarity coefficient between these two isolates and the rest, ranged from 57.9% to 68.4% and the corresponding dendrogram clustered TeAp-N/D1 and Te Gu-N/D1 in a genetically distinct group.

  6. Molecular evidence for the origin of the widespread Venezuelan equine encephalitis epizootic of 1969 to 1972.

    PubMed

    Kinney, R M; Tsuchiya, K R; Sneider, J M; Trent, D W

    1992-12-01

    Venezuelan equine encephalitis (VEE) virus is a mosquito-borne pathogen that has caused encephalitis in equine species and humans during sporadic outbreaks in the western hemisphere. The last, and most widespread, VEE outbreak occurred in South America, Central America, Mexico and the U.S.A. (Texas) during 1969 to 1972. We have cloned and sequenced the genome of a virulent VEE subtype I-AB virus, strain 71-180, isolated in Texas in 1971. Thirty-four nucleotide differences were detected between the genome of 71-180 virus and that of the subtype I-AB Trinidad donkey (TRD) virus isolated during the 1943 VEE epizootic in Trinidad. Fifteen nucleotide changes occurred in the non-structural genes, 16 in the structural genes and three in the 3' non-coding region. Only six of the nucleotide differences resulted in amino acid substitutions: one change in each of non-structural proteins nsP1 and nsP3, two in the E2 envelope glycoprotein, one in the 6K polypeptide and one in the E1 envelope glycoprotein. The close genetic relationship between 71-180 virus and TRD virus, commonly used for production of formalin-inactivated VEE vaccines, suggests that incompletely inactivated virulent vaccine virus may have been the source of this and other VEE outbreaks. Use of formalized virulent virus was discontinued during the 1969 to 1972 panzootic. No VEE epizootics have been reported since the introduction of the live attenuated TC-83 vaccine virus.

  7. [Presence of lectins, tannins and protease inhibitors in venezuelan marine algae].

    PubMed

    Perez-Lorenzo, S; Levy-Benshimol, A; Gomez-Acevedo, S

    1998-01-01

    The presence of lectins, tannins and protease inhibitors was studied in 27 algae species collected at four Venezuelan coral rift sites. Among the species studied, only six had hemagglutinating activity, apparently due to their lectin content. Higher hemagglutinating titers were obtained when the extracts were tested on pronase-treated erythrocytes. Hemagglutination was inhibited by simple sugars and by bovine submaxillary gland mucine. GaINAc was the only inhibitor of the hemagglutination caused by Grateulopia filicina extracts. None of the compounds tested inhibited the hemagglutination caused by Halimeda opuntia. The polyvinylpolypirrolidone treatment abolished the hemagglutinating activity of both brown and red algae. However, in Grateulopia filicina and Hypnea cervicornis (Rhodophyta) hemagglutinating activity persisted after the polyvinylpolypirrolidone treatment, presumably due to the presence of true lectins in those algae. Tannin content (presumably phlorotannins) was higher in the Phaeophyta as compared to the Rhodophyta. The brown alga Padina gymnospora had the higher content of these polyphenols. Trypsin inhibitors were detected, in minute ammounts, only in Padina gymnospora (Phaeophyta) and Acantophora spicifera (Rhodophyta). No subtilisin inhibition was observed whatsoever.

  8. Noncytopathic replication of Venezuelan equine encephalitis virus and eastern equine encephalitis virus replicons in Mammalian cells.

    PubMed

    Petrakova, Olga; Volkova, Eugenia; Gorchakov, Rodion; Paessler, Slobodan; Kinney, Richard M; Frolov, Ilya

    2005-06-01

    Venezuelan equine encephalitis (VEE) and eastern equine encephalitis (EEE) viruses are important, naturally emerging zoonotic viruses. They are significant human and equine pathogens which still pose a serious public health threat. Both VEE and EEE cause chronic infection in mosquitoes and persistent or chronic infection in mosquito-derived cell lines. In contrast, vertebrate hosts infected with either virus develop an acute infection with high-titer viremia and encephalitis, followed by host death or virus clearance by the immune system. Accordingly, EEE and VEE infection in vertebrate cell lines is highly cytopathic. To further understand the pathogenesis of alphaviruses on molecular and cellular levels, we designed EEE- and VEE-based replicons and investigated their replication and their ability to generate cytopathic effect (CPE) and to interfere with other viral infections. VEE and EEE replicons appeared to be less cytopathic than Sindbis virus-based constructs that we designed in our previous research and readily established persistent replication in BHK-21 cells. VEE replicons required additional mutations in the 5' untranslated region and nsP2 or nsP3 genes to further reduce cytopathicity and to become capable of persisting in cells with no defects in alpha/beta interferon production or signaling. The results indicated that alphaviruses strongly differ in virus-host cell interactions, and the ability to cause CPE in tissue culture does not necessarily correlate with pathogenesis and strongly depends on the sequence of viral nonstructural proteins.

  9. Endemic Venezuelan equine encephalitis in the Americas: hidden under the dengue umbrella

    PubMed Central

    Aguilar, Patricia V; Estrada-Franco, Jose G; Navarro-Lopez, Roberto; Ferro, Cristina; Haddow, Andrew D; Weaver, Scott C

    2011-01-01

    Venezuelan equine encephalitis (VEE) is an emerging infectious disease in Latin America. Outbreaks have been recorded for decades in countries with enzootic circulation, and the recent implementation of surveillance systems has allowed the detection of additional human cases in countries and areas with previously unknown VEE activity. Clinically, VEE is indistinguishable from dengue and other arboviral diseases and confirmatory diagnosis requires the use of specialized laboratory tests that are difficult to afford in resource-limited regions. Thus, the disease burden of endemic VEE in developing countries remains largely unknown, but recent surveillance suggests that it may represent up to 10% of the dengue burden in neotropical cities, or tens-of-thousands of cases per year throughout Latin America. The potential emergence of epizootic viruses from enzootic progenitors further highlights the need to strengthen surveillance activities, identify mosquito vectors and reservoirs and develop effective strategies to control the disease. In this article, we provide an overview of the current status of endemic VEE that results from spillover of the enzootic cycles, and we discuss public health measures for disease control as well as future avenues for VEE research. PMID:21765860

  10. Glaciation and topographic evolution of the Central Patagonian Andes since 6 Ma

    NASA Astrophysics Data System (ADS)

    Christeleit, E. C.; Laemel, R.; De Wolf, W. E.; Shuster, D. L.; Brandon, M. T.

    2013-12-01

    New and existing thermochronological data are used to model glacial erosion and topographic evolution of the central Patagonian Andes (~47S) over the last 6 Ma. The modern Andes are cut by large valleys and fjords with local valley relief of at least 2.5 km. It is currently thought that a formerly uniformly high Andes was 'buzzed' down to the elevation of the equilibrium line altitude, presumably in the last 2 Ma concurrent with late Cenozoic global cooling. However, studies of glacial debris show that glaciers were present in Patagonia as early as 6 Ma. The extent of these early glaciations is unclear, but recent work suggests that glacial valleys in the central Patagonian Andes were carved at a steady rate beginning at 6 Ma, implying that valley incision may be an important process in the topographic evolution of glaciated mountain ranges, rather than cirque retreat. To understand how valley relief has formed in the Andes, we dated 30 samples from Steffen Fjord in Chile using apatite (U-Th)/He thermochronology. We use this new data and existing thermochronological data in the region to estimate the topographic form of the central Andes at 6 Ma and model how the valley relief has evolved since the initiation of glaciation using Pecube.

  11. Shear wave anisotropy in northwestern South America and its link to the Caribbean and Nazca subduction geodynamics

    NASA Astrophysics Data System (ADS)

    Idárraga-García, J.; Kendall, J.-M.; Vargas, C. A.

    2016-09-01

    To investigate the subduction dynamics in northwestern South America, we measured SKS and slab-related local S splitting at 38 seismic stations. Comparison between the delay times of both phases shows that most of the SKS splitting is due to entrained mantle flow beneath the subducting Nazca and Caribbean slabs. On the other hand, the fast polarizations of local S-waves are consistently aligned with regional faults, which implies the existence of a lithosphere-confined anisotropy in the overriding plate, and that the mantle wedge is not contributing significantly to the splitting. Also, we identified a clear change in SKS fast directions at the trace of the Caldas Tear (˜5°N), which represents a variation in the subduction style. To the north of ˜5°N, fast directions are consistently parallel to the flat subduction of the Caribbean plate-Panama arc beneath South America, while to the south fast polarizations are subparallel to the Nazca-South America subduction direction. A new change in the SKS splitting pattern is detected at ˜2.8°N, which is related to another variation in the subduction geometry marked by the presence of a lithosphere-scale tearing structure, named here as Malpelo Tear; in this region, NE-SW-oriented SKS fast directions are consistent with the general dip direction of the underthrusting of the Carnegie Ridge beneath South America. Further inland, this NE-SW-trending mantle flow continues beneath the Eastern Cordillera of Colombia and Merida Andes of Venezuela. Finally, our results suggest that the subslab mantle flow in northwestern South America is strongly controlled by the presence of lithospheric tearing structures.

  12. Seismological observations in Northwestern South America: Evidence for two subduction segments, contrasting crustal thicknesses and upper mantle flow

    NASA Astrophysics Data System (ADS)

    Yarce, Jefferson; Monsalve, Gaspar; Becker, Thorsten W.; Cardona, Agustín; Poveda, Esteban; Alvira, Daniel; Ordoñez-Carmona, Oswaldo

    2014-12-01

    The cause of tectonic deformation in northwestern South America and its link to upper mantle structure and flow are debated. We use a combination of broadband and short period travel time seismic data for P-waves to show that observations are consistent with the presence of two subduction segments in Colombia and contrasting values of crustal thickness. In Northern Colombia, at latitudes greater than 6°N, most of the seismic stations are associated with negative teleseismic travel time residuals, relative to a regional mean, suggesting that the upper mantle is seismically faster than predicted from global models. In particular, for the Caribbean coastal plains there are no signs of significant anomalies in the upper mantle, evidenced by the small magnitude of the travel time delays and subdued Pn speeds (~ 7.97 km/s). To the southeast of such plains there is an increase in magnitude of the negative travel time residuals, including the Northern Eastern Cordillera, the Perija Range and the Merida Andes. An analysis of non-isostatic residual topography, based on a model of crustal thickness in northwestern South America, is consistent with a slab-associated upper mantle flow beneath the region just east of the Bucaramanga Nest. We interpret these results to indicate the presence of a Caribbean slab, initially flat beneath the Caribbean coastal plains, and steepening sharply in the southeast, including the area of Bucaramanga. For most of the western Andean region and the Pacific coast, south of 6°N, teleseismic differential travel time residuals are predominantly positive, indicating that the upper mantle is in general seismically slower than the reference model. Beneath the Central Cordillera, just to the east of this area, the residuals become smaller and predominantly negative; residual non-isostatic topography is negative as well. These features are probably related to the effect of the Nazca subduction developing an asthenospheric wedge.

  13. Molecular characterization and classification of Trypanosoma spp. Venezuelan isolates based on microsatellite markers and kinetoplast maxicircle genes.

    PubMed

    Sánchez, E; Perrone, T; Recchimuzzi, G; Cardozo, I; Biteau, N; Aso, P M; Mijares, A; Baltz, T; Berthier, D; Balzano-Nogueira, L; Gonzatti, M I

    2015-10-15

    Livestock trypanosomoses, caused by three species of the Trypanozoon subgenus, Trypanosoma brucei brucei, T. evansi and T. equiperdum is widely distributed throughout the world and constitutes an important limitation for the production of animal protein. T. evansi and T. equiperdum are morphologically indistinguishable parasites that evolved from a common ancestor but acquired important biological differences, including host range, mode of transmission, distribution, clinical symptoms and pathogenicity. At a molecular level, T. evansi is characterized by the complete loss of the maxicircles of the kinetoplastic DNA, while T. equiperdum has retained maxicircle fragments similar to those present in T. brucei. T. evansi causes the disease known as Surra, Derrengadera or "mal de cadeiras", while T. equiperdum is the etiological agent of dourine or "mal du coit", characterized by venereal transmission and white patches in the genitalia. Nine Venezuelan Trypanosoma spp. isolates, from horse, donkey or capybara were genotyped and classified using microsatellite analyses and maxicircle genes. The variables from the microsatellite data and the Procyclin PE repeats matrices were combined using the Hill-Smith method and compared to a group of T. evansi, T. equiperdum and T. brucei reference strains from South America, Asia and Africa using Coinertia analysis. Four maxicircle genes (cytb, cox1, a6 and nd8) were amplified by PCRfrom TeAp-N/D1 and TeGu-N/D1, the two Venezuelan isolates that grouped with the T. equiperdum STIB841/OVI strain. These maxicircle sequences were analyzed by nucleotide BLAST and aligned toorthologous genes from the Trypanozoon subgenus by MUSCLE tools. Phylogenetic trees were constructed using Maximum Parsimony (MP) and Maximum Likelihood (ML) with the MEGA5.1® software. We characterized microsatellite markers and Procyclin PE repeats of nine Venezuelan Trypanosoma spp. isolates with various degrees of virulence in a mouse model, and compared them to a

  14. 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

  15. 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.

  16. Preliminary bathymetry of Northwestern Fiord and Neoglacial changes of Northwestern Glacier

    USGS Publications Warehouse

    Post, Austin

    1980-01-01

    The first preliminary bathymetry (at 1:20,000 scale) and other scientific investigations of Northwestern Fiord, Alaska, were conducted by the Research Vessel Growler in 1978, disclosing this 10.5-mile-long branched waterway to be a deep basin enclosed by a terminal-moraine shoal. The basin was formerly filled by Northwestern Glacier, which began a drastic retreat around 1909 and reached the head of the main arm around 1960. Soundings and profiles show the main channel to be as much as 970 feet deep and to have the typical U shape of a severely glacially eroded valley; since the glacier 's retreat, sediments have formed nearly level deposits in the deepest reaches, while the rest of the basin has a hard, rocky bottom. Preneoglacial forest debris dated by carbon-14 indicates Northwestern Glacier to have advanced into the fiord prior to 1,385 years before present (B.P.); a branch glacier evidently advanced into forest 1,635 years B.P. The combined glaciers from several arms culminated on the present terminal-moraine shoal around 1894. (USGS)

  17. The Northwestern University Neuroimaging Data Archive (NUNDA)

    PubMed Central

    Alpert, Kathryn; Kogan, Alexandr; Parrish, Todd; Marcus, Daniel; Wang, Lei

    2015-01-01

    The Northwestern University Neuroimaging Data Archive (NUNDA), an XNAT-powered data archiving system, aims to facilitate secure data storage; centralized data management; automated, standardized data processing; and simple, intuitive data sharing. NUNDA is a federated data archive, wherein individual project owners regulate access to their data. NUNDA supports multiple methods of data import, enabling data collection in a central repository. Data in NUNDA are available by project to any authorized user, allowing coordinated data management and review across sites. With NUNDA pipelines, users capitalize on existing procedures or standardize custom routines for consistent, automated data processing. NUNDA can be integrated with other research databases to simplify data exploration and discovery. And data on NUNDA can be confidently shared for secure collaboration. PMID:26032888

  18. Northwestern Mexico as photographed from Skylab

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An oblique view of northwestern Mexico (30.0N, 113.5W), as photographed from the Skylab space station in Earth orbit by one of the Skylab 4 crewmen. This photograph was taken on a seep down the coast to document the fault patterns of southern California and northwest Mexico. The specific reason for the picture was to see of the Agua Blanca Fault in Baja California extends to the east toward the Gulf of California. No such extension was found. The fault appeard to disappear into an area of sand and heavily eroded material that obscured any feature that might be present deeper. This area of sand and loose material is the light-colored area in the center of Baja at the extreme north part of the photograph.

  19. Petroleum in the Junggar basin, northwestern China

    NASA Astrophysics Data System (ADS)

    Taner, Irfan; Kamen-Kaye, Maurice; Meyerhoff, Arthur A.

    The Junggar basin occupies a large triangular area of some 130 000 km 2 in northwestern China. Situated between the Altay Shan (Altay Range) on the northeast and the Tian Shan (Tian Range) on the southwest, and between lesser ranges around the remainder of its periphery, the Junggar basin is completely intermontane. Its history as a basin began in the Permian, and continued as various uplifts and downwarps evolved. Through the Paleozoic the characteristics of the Junggar basin area were largely geosynclinal and marine. Its post-Permian development took place exclusively in continental regimes. Inhabitants of the Junggar basin have known and utilized its numerous oil and asphalt seeps and its spectacular spreads of asphalt for more than 2000 years, especially in the Karamay-Urho thrust belt near the northwestern rim. The first discovery of oil in the modern sense came at Dushanzi, one of the steeply folded anticlines of theÜrümqi foredeep near the southern rim. The first shallow oil in the Karamay-Urho thrust belt came in 1937, followed by commercial production in the Karamay field in 1955. Output continued to be modest until wells were drilled through local thrusts and reverse faults in the early 1980s. By 1985, cumulative production of the Karamay group of fields had reached 42,000,000 t (metric tonnes) (306,000,000 bbl), with a calculated minimum ultimate recovery of 280,000,000 t (2 billion bbl). Principal production comes from Permian and Triassic strata in continental facies. Apart from marine Mid and Upper Carboniferous strata, source rocks occur mainly in fine-grained lacustrine detrital beds of the Permian, the Triassic, the Jurassic and the Tertiary. Several uplifts and downwarps elsewhere in the Junggar basin remain to be drilled comprehensively. Results from such drilling may enhance the very important position that the Junggar already has attained in the hierarchy of China's onshore basins.

  20. 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

  1. Across the southern Andes on fin: glacial refugia, drainage reversals and a secondary contact zone revealed by the phylogeographical signal of Galaxias platei in Patagonia.

    PubMed

    Zemlak, Tyler S; Habit, Evelyn M; Walde, Sandra J; Battini, Miguel A; Adams, Emily D M; Ruzzante, Daniel E

    2008-12-01

    We employed DNA sequence variation at two mitochondrial (control region, COI) regions from 212 individuals of Galaxias platei (Pisces, Galaxiidae) collected throughout Patagonia (25 lakes/rivers) to examine how Andean orogeny and the climatic cycles throughout the Quaternary affected the genetic diversity and phylogeography of this species. Phylogenetic analyses revealed four deep genealogical lineages which likely represent the initial division of G. platei into eastern and western lineages by Andean uplift, followed by further subdivision of each lineage into separate glacial refugia by repeated Pleistocene glacial cycles. West of the Andes, refugia were likely restricted to the northern region of Patagonia with small relicts in the south, whereas eastern refugia appear to have been much larger and widespread, consisting of separate northern and southern regions that collectively spanned most of Argentinean Patagonia. The retreat of glacial ice following the last glacial maximum allowed re-colonization of central Chile from nonlocal refugia from the north and east, representing a region of secondary contact between all four glacial lineages. Northwestern glacial relicts likely followed pro-glacial lakes into central Chilean Patagonia, whereas catastrophic changes in drainage direction (Atlantic --> Pacific) for several eastern palaeolakes were the likely avenues for invasions from the east. These mechanisms, combined with evidence for recent, rapid and widespread population growth could explain the extensive contemporary distribution of G. platei throughout Patagonia.

  2. Into the Andes: multiple independent colonizations drive montane diversity in the Neotropical clearwing butterflies Godyridina.

    PubMed

    Chazot, Nicolas; Willmott, Keith R; Condamine, Fabien L; De-Silva, Donna Lisa; Freitas, André V L; Lamas, Gerardo; Morlon, Hélène; Giraldo, Carlos E; Jiggins, Chris D; Joron, Mathieu; Mallet, James; Uribe, Sandra; Elias, Marianne

    2016-11-01

    Understanding why species richness peaks along the Andes is a fundamental question in the study of Neotropical biodiversity. Several biogeographic and diversification scenarios have been proposed in the literature, but there is confusion about the processes underlying each scenario, and assessing their relative contribution is not straightforward. Here, we propose to refine these scenarios into a framework which evaluates four evolutionary mechanisms: higher speciation rate in the Andes, lower extinction rates in the Andes, older colonization times and higher colonization rates of the Andes from adjacent areas. We apply this framework to a species-rich subtribe of Neotropical butterflies whose diversity peaks in the Andes, the Godyridina (Nymphalidae: Ithomiini). We generated a time-calibrated phylogeny of the Godyridina and fitted time-dependent diversification models. Using trait-dependent diversification models and ancestral state reconstruction methods we then compared different biogeographic scenarios. We found strong evidence that the rates of colonization into the Andes were higher than the other way round. Those colonizations and the subsequent local diversification at equal rates in the Andes and in non-Andean regions mechanically increased the species richness of Andean regions compared to that of non-Andean regions ('species-attractor' hypothesis). We also found support for increasing speciation rates associated with Andean lineages. Our work highlights the importance of the Andean slopes in repeatedly attracting non-Andean lineages, most likely as a result of the diversity of habitats and/or host plants. Applying this analytical framework to other clades will bring important insights into the evolutionary mechanisms underlying the most species-rich biodiversity hotspot on the planet.

  3. 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

  4. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Human papillomavirus and Epstein Barr virus in oral hairy leukoplakia among HIV positive Venezuelan patients.

    PubMed

    Correnti, María; González, Xiomara; Avila, Maira; Perrone, Marianella; Rivera, Helen

    2010-01-01

    Oral hairy leukoplakia (OHL) is commonly found in individuals infected with HIV and represents the most frequent oral manifestation. The purpose of this study was to detect the presence of Human Papillomavirus (HPV) and Epstein Barr Virus (EBV) in OHL of HIV+ Venezuelan patients. We evaluated 21 HIV+ adult patients with clinically present OHL lesions: 11 under antiretroviral therapy, 10 without therapy, and 10 oral mucosal samples as controls. Nested-PCR was used to detect EBV and HPV infection. The INNO-LiPA HPV Genotyping v2 was applied to determine the HPV genotype. The EBV genome was found in 16/21 (76%) of the HIV+ patients with OHL. No difference was observed in EBV+ and EBV- patients related to antiretroviral therapy viral load and CD4+ Tcell coant. HPV-DNA was observed in 7/21 HIV positive cases (33%). The HPV genotypes detected were: 6, 11, 31, 33, 52, and 56/74. The most frequently HPV found was genotype 6 in 7/7, while two cases were HPV-11 and two HPV-52. Of the positive cases, 5/7 (71%) presented co-infection with more than one HPV genotype and 4/7 (57%) had HPV coinfection with high and low risk types. No case was EBV or HPV positive in the control group. In this study, a higher EBV prevalence was observed in OHL-HIV+ patients, confirming the etiologic role in this entity. A considerable number of cases were positive for HPV infection, and many patients presented coinfection with more than one HPV genotype as well as the presence of high oncogenic risk HPV in OHL.

  6. [Detection of human papillomavirus in gingival fluid of Venezuelan HIV patients with periodontal disease].

    PubMed

    Escalona, Laura; Correnti, María; Veitía, Dayahindira; Perrone, Marianella

    2011-09-01

    Evidence suggests that viruses may be involved in the activation of periodontal disease, allowing the overgrowth of periodontal pathogens. The purpose of the present study was to detect the presence of Human Papillomavirus (HPV) in gingival crevicular fluid (GCF) in HIV+ Venezuelan patients with periodontal disease. We evaluated GCF samples from 20 HIV+ patients with periodontal disease from the Infectious Disease Center, Faculty of Dentistry, Central University of Venezuela, and were clinically examined to establish their periodontal conditions, 13 under HAART (antiretroviral therapy) and 7 without HAART. Seven seronegative patients with chronic periodontitis and 7 seronegative patients, without periodontal disease were included. DNA extraction was performed, the consensus primers MY09 and MY11 for the HPV L1 region were used for PCR amplification. Genotipification was made for the 6, 11, 16, 18, 31 and 45 genotypes. HPV were detected in 46% of HIV+ patients under therapy. The CD4 cell counts in the IIPV+ patients were not significantly different from the HPV-group. The viral load in the HPV+ group was significantly higher (200,470 +/- 324,244 copy/mL) than in the HPV-patients (10,246 +/- 23,805 copy/mL). Genotypes 6 and 11 were observed in the HPV positive samples, of which 4/6 (66.6%) presented coinfection with both types. No significant differences in the periodontal conditions were observed between patients with IIPV-HIV infection related to patients with only HIV. HPV was detected only in the gingival crevicular fluid of HIV+ patients under HAART independently of the periodontal conditions.

  7. 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

  8. Evidence of suppression of onchocerciasis transmission in the Venezuelan Amazonian focus.

    PubMed

    Botto, Carlos; Basañez, María-Gloria; Escalona, Marisela; Villamizar, Néstor J; Noya-Alarcón, Oscar; Cortez, José; Vivas-Martínez, Sarai; Coronel, Pablo; Frontado, Hortencia; Flores, Jorge; Graterol, Beatriz; Camacho, Oneida; Tovar, Yseliam; Borges, Daniel; Morales, Alba Lucia; Ríos, Dalila; Guerra, Francisco; Margeli, Héctor; Rodriguez, Mario Alberto; Unnasch, Thomas R; Grillet, María Eugenia

    2016-01-27

    The World Health Organization (WHO) has set goals for onchocerciasis elimination in Latin America by 2015. Most of the six previously endemic countries are attaining this goal by implementing twice a year (and in some foci, quarterly) mass ivermectin (Mectizan®) distribution. Elimination of transmission has been verified in Colombia, Ecuador and Mexico. Challenges remain in the Amazonian focus straddling Venezuela and Brazil, where the disease affects the hard-to-reach Yanomami indigenous population. We provide evidence of suppression of Onchocerca volvulus transmission by Simulium guianense s.l. in 16 previously hyperendemic Yanomami communities in southern Venezuela after 15 years of 6-monthly and 5 years of 3-monthly mass ivermectin treatment. Baseline and monitoring and evaluation parasitological, ophthalmological, entomological and serological surveys were conducted in selected sentinel and extra-sentinel communities of the focus throughout the implementation of the programme. From 2010 to 2012-2015, clinico-parasitological surveys indicate a substantial decrease in skin microfilarial prevalence and intensity of infection; accompanied by no evidence (or very low prevalence and intensity) of ocular microfilariae in the examined population. Of a total of 51,341 S. guianense flies tested by PCR none had L3 infection (heads only). Prevalence of infective flies and seasonal transmission potentials in 2012-2013 were, respectively, under 1% and 20 L3/person/transmission season. Serology in children aged 1-10 years demonstrated that although 26 out of 396 (7%) individuals still had Ov-16 antibodies, only 4/218 (2%) seropositives were aged 1-5 years. We report evidence of recent transmission and morbidity suppression in some communities of the focus representing 75% of the Yanomami population and 70% of all known communities. We conclude that onchocerciasis transmission could be feasibly interrupted in the Venezuelan Amazonian focus.

  9. Potential Sources of the 1995 Venezuelan Equine Encephalitis Subtype IC Epidemic

    PubMed Central

    Brault, Aaron C.; Powers, Ann M.; Medina, Gladys; Wang, Eryu; Kang, Wenli; Salas, Rosa Alba; De Siger, Julieta; Weaver, Scott C.

    2001-01-01

    Venezuelan equine encephalitis viruses (VEEV) belonging to subtype IC have caused three (1962–1964, 1992–1993 and 1995) major equine epizootics and epidemics. Previous sequence analyses of a portion of the envelope glycoprotein gene demonstrated a high degree of conservation among isolates from the 1962–1964 and the 1995 outbreaks, as well as a 1983 interepizootic mosquito isolate from Panaquire, Venezuela. However, unlike subtype IAB VEEV that were used to prepare inactivated vaccines that probably initiated several outbreaks, subtype IC viruses have not been used for vaccine production and their conservation cannot be explained in this way. To characterize further subtype IC VEEV conservation and to evaluate potential sources of the 1995 outbreak, we sequenced the complete genomes of three isolates from the 1962–1964 outbreak, the 1983 Panaquire interepizootic isolate, and two isolates from 1995. The sequence of the Panaquire isolate, and that of virus isolated from a mouse brain antigen prepared from subtype IC strain P676 and used in the same laboratory, suggested that the Panaquire isolate represents a laboratory contaminant. Some authentic epizootic IC strains isolated 32 years apart showed a greater degree of sequence identity than did isolates from the same (1962–1964 or 1995) outbreak. If these viruses were circulating and replicating between 1964 and 1995, their rate of sequence evolution was at least 10-fold lower than that estimated during outbreaks or that of closely related enzootic VEEV strains that circulate continuously. Current understanding of alphavirus evolution is inconsistent with this conservation. This subtype IC VEEV conservation, combined with phylogenetic relationships, suggests the possibility that the 1995 outbreak was initiated by a laboratory strain. PMID:11390583

  10. Candidate vaccine against botulinum neurotoxin serotype A derived from a Venezuelan equine encephalitis virus vector system.

    PubMed

    Lee, J S; Pushko, P; Parker, M D; Dertzbaugh, M T; Smith, L A; Smith, J F

    2001-09-01

    A candidate vaccine against botulinum neurotoxin serotype A (BoNT/A) was developed by using a Venezuelan equine encephalitis (VEE) virus replicon vector. This vaccine vector is composed of a self-replicating RNA containing all of the VEE nonstructural genes and cis-acting elements and also a heterologous immunogen gene placed downstream of the subgenomic 26S promoter in place of the viral structural genes. In this study, the nontoxic 50-kDa carboxy-terminal fragment (H(C)) of the BoNT/A heavy chain was cloned into the replicon vector (H(C)-replicon). Cotransfection of BHK cells in vitro with the H(C)-replicon and two helper RNA molecules, the latter encoding all of the VEE structural proteins, resulted in the assembly and release of propagation-deficient, H(C) VEE replicon particles (H(C)-VRP). Cells infected with H(C)-VRP efficiently expressed this protein when analyzed by either immunofluorescence or by Western blot. To evaluate the immunogenicity of H(C)-VRP, mice were vaccinated with various doses of H(C)-VRP at different intervals. Mice inoculated subcutaneously with H(C)-VRP were protected from an intraperitoneal challenge of up to 100,000 50% lethal dose units of BoNT/A. Protection correlated directly with serum enzyme-linked immunosorbent assay titers to BoNT/A. The duration of the immunity achieved was tested at 6 months and at 1 year postvaccination, and mice challenged at these times remained refractory to challenge with BoNT/A.

  11. Venezuelan Equine Encephalitis Replicon Particles Can Induce Rapid Protection against Foot-and-Mouth Disease Virus

    PubMed Central

    Diaz-San Segundo, Fayna; Dias, Camila C. A.; Moraes, Mauro P.; Weiss, Marcelo; Perez-Martin, Eva; Owens, Gary; Custer, Max; Kamrud, Kurt; de los Santos, Teresa

    2013-01-01

    We have previously shown that delivery of the porcine type I interferon gene (poIFN-α/β) with a replication-defective human adenovirus vector (adenovirus 5 [Ad5]) can sterilely protect swine challenged with foot-and-mouth disease virus (FMDV) 1 day later. However, the need of relatively high doses of Ad5 limits the applicability of such a control strategy in the livestock industry. Venezuelan equine encephalitis virus (VEE) empty replicon particles (VRPs) can induce rapid protection of mice against either homologous or, in some cases, heterologous virus challenge. As an alternative approach to induce rapid protection against FMDV, we have examined the ability of VRPs containing either the gene for green fluorescent protein (VRP-GFP) or poIFN-α (VRP-poIFN-α) to block FMDV replication in vitro and in vivo. Pretreatment of swine or bovine cell lines with either VRP significantly inhibited subsequent infection with FMDV as early as 6 h after treatment and for at least 120 h posttreatment. Furthermore, mice pretreated with either 107 or 108 infectious units of VRP-GFP and challenged with a lethal dose of FMDV 24 h later were protected from death. Protection was induced as early as 6 h after treatment and lasted for at least 48 h and correlated with induction of an antiviral response and production of IFN-α. By 6 h after treatment several genes were upregulated, and the number of genes and the level of induction increased at 24 h. Finally, we demonstrated that the chemokine IP-10, which is induced by IFN-α and VRP-GFP, is directly involved in protection against FMDV. PMID:23468490

  12. Venezuelan equine encephalitis vaccination survey in Arizona and New Mexico, 1972.

    PubMed

    Moore, R M; Moulthrop, J I; Sather, G E; Holmes, C L; Parker, R L

    1977-01-01

    Field studies were conducted in 1972 to determine the immunization status of equines along the Mexico, Arizona, and New Mexico borders. Interviews with horse owners were conducted along roads selected at random in the counties of Santa Cruz and Yuma, Ariz., and in Dona Ana County, N. Mex. At least 450 horse owners in each county were asked about the vaccination status of their animals, and information was taken on 1,260 animals. Blood specimens were obtained from every third equine, regardless of stated vaccination status, and tested for the presence of Venezuelan equine encephalitis (VEE), western equine encephalomyelitis (WEE), and eastern equine encephalomyelitis (EEE) neutralization antibodies. Serum samples were collected from 446 equines in the 3-county area; only 227 (50.7 percent) had both a history of VEE vaccination in 1971 (including 20 vaccinated in 1972) and serum neutralization antibody against VEE. Of the remaining 220 with no detectable neutralization antibody to VEE, 197 (89.5 percent) had a history of VEE vaccination in 1971 (including 5 revaccinated in 1972), 14 (6.4 percent) had no history of vaccination, and 9 (4.1 percent) had an unknown vaccination status. Eighty-two percent (160 of 1971) of the equines with a history of VEE vaccination and presence of dectectable WEE or EEE antibodies, or both, had no detectable levels of VEE antibody. Therefore, the results of this study suggest that the presence of WEE or EEE antibodies, or both, may suppress the development of dectable vaccine-induced VEE antibody response in the equine. As a result of this investigation, the U.S. Department of Agriculture, as an added precaution, recommended the revaccination of equines in areas of the United States bordering Mexico.

  13. Needle coke and carbon fiber production from Venezuelan oil residues. (Volumes I and II)

    SciTech Connect

    Rodriguez, J.

    1992-01-01

    The conversion of high boiling petroleum residues to carbonaceous materials is investigated. A new integrated approach is presented in which Nuclear Magnetic Resonance (NMR) spectroscopy, optical microscopy, physico-chemical separations, and pilot plant operations are combined to better understand the carbonization process and to develop criteria for prediction of product quality. This methodology is applied to several Venezuelan oil residues obtained from refinery and pilot plant operations to evaluate their potential for producing high value carbon products such as needle coke and carbon fibers. Feedstocks, reaction intermediates, and products are characterized by [sup 1]H and [sup 13]C NMR in terms of basic hydrocarbon constituents, and changes in carbon and proton distributions are measured. The extent of aromatization and other structural changes resulting from thermal cracking reactions are calculated for the first time by combining pilot plant data with NMR spectroscopic data in both the liquid and solid states. Improved methods for interpreting NMR data of liquid and solid materials from petroleum residues are developed. The effects of operating conditions and the role of different fractions obtained by distillation, n-pentane extraction and high performance liquid chromatography during reaction are documented. Delayed coking and thermal cracking pilot plant experiments were designed and carried out to simulate refinery operation and to provide samples for further characterization. Representative samples of coke were evaluated for use as electrodes in electric arc furnaces. It is shown that by proper selection of feedstock and operational parameters, premium quality needle cokes can be produced. A laboratory scale melt spinning apparatus to produce continuous mesophase pitch carbon fibers was designed and built. The ability to produce thin filaments (less than 20 [mu]m diameter) from petroleum pitches was demonstrated.

  14. Integrated geological model in a transect of the Eastern Venezuelan Basin

    SciTech Connect

    Passalacqua, H.; Gou, I. ); Truskowski, I.; Di Croce, J. )

    1992-01-01

    The generation, migration and accumulation of hydrocarbons are among the most controversial problems of petroleum exploration in platform and, more especially, complex areas such as thrusted zones. The understanding of these phenomena is essential for the explorationist and is facilitated with the use of mathematical models which enable the integration and assimilation of parameters varying with time and space. In order to carry out this mathematical model an integrated synthesis is necessary. It should include stratigraphic, structural, reservoir and geochemical data. The elaboration of a geological model along a transect in the Eastern Venezuelan Basin was conducted to prepare data for the mathematical modeling application. The main results of the synthesis are: The elaboration of a reliable stratigraphic model including updated ages. A coherent structural interpretation in thrusted zones, validated by the balancing of North-South cross sections. The most relevant findings are: The identification of out-of-sequence thrusts and the involvement of the Upper Crust in the deformation processes. The elaboration of reservoir and hydrodynamic models which point out the importance of the major reservoirs. A characterization of the three different source-rocks of marine and continental origin in the Guayuta Group and Carapita Formation and the comprehension of their maturity, expulsion and migration processes with regards to the structural history. In this way the generation of 1,350 to 3,300 [times] 10[sup 9] barrels of oil has been estimated, of which 6 to 15 percent have been recognized within the transect. The final mathematical modeling, with the input of these synthetical data will be carried out with the use of the available software in the platform area. New software is presently being developed for thrusted areas.

  15. Water relations of epiphytic and terrestrially-rooted strangler figs in a Venezuelan palm savanna.

    PubMed

    Holbrook, N Michele; Putz, Francis E

    1996-06-01

    Water use patterns of two species of strangler fig, Ficus pertusa and F. trigonata, growing in a Venezuelan palm savanna were contrasted in terms of growth phase (epiphyte and tree) and season (dry and wet). The study was motivated by the question of how C3 hemiepiphytes accommodate the marked change in rooting environment associated with a life history of epiphytic establishment followed by substantial root development in the soil. During the dry season, stomatal opening in epiphytic plants occurred only during the early morning, maximum stomatal conductances were 5 to 10-fold lower, and midday leaf water potentials were 0.5-0.8 MPa higher (less negative) than in conspecific trees. Watering epiphytes of F. pertusa during the dry season led to stomatal conductances comparable to those exhibited by conspecific trees, but midday leaf water potentials were unchanged. During the rainy season, epiphytes had lower stomatal conductances than conspecific trees, but leaf water potentials were similar between the two growth phases. There were no differences in ∂(13)C between the two growth phases for leaves produced in either season. Substrate water availability differed between growth phases; tree roots extended down to the permanent water table, while roots of epiphytic plants were restricted to material accumulated behind the persistent leaf bases of their host palm tree, Copernicia tectorum. Epiphytic substrate moisture contents were variable during both seasons, indicating both the availability of some moisture during the dry season and the possibility of intermittent depletion during the rainy season. Epiphytic strangler figs appear to rely on a combination of strong stomatal control, maintenance of high leaf water potentials, and perhaps some degree of stem water storage to cope with the fluctuating water regime of the epiphytic environment.

  16. Replicon particles of Venezuelan equine encephalitis virus as a reductionist murine model for encephalitis.

    PubMed

    Schäfer, Alexandra; Whitmore, Alan C; Konopka, Jennifer L; Johnston, Robert E

    2009-05-01

    Venezuelan equine encephalitis virus (VEE) replicon particles (VRP) were used to model the initial phase of VEE-induced encephalitis in the mouse brain. VRP can target and infect cells as VEE, but VRP do not propagate beyond the first infected cell due to the absence of the structural genes. Direct intracranial inoculation of VRP into mice induced acute encephalitis with signs similar to the neuronal phase of wild-type VEE infection and other models of virus-induced encephalitis. Using the previously established VRP-mRNP tagging system, a new method to distinguish the host responses in infected cells from those in uninfected bystander cell populations, we detected a robust and rapid innate immune response in the central nervous system (CNS) by infected neurons and uninfected bystander cells. Moreover, this innate immune response in the CNS compromised blood-brain barrier integrity, created an inflammatory response, and directed an adaptive immune response characterized by proliferation and activation of microglia cells and infiltration of inflammatory monocytes, in addition to CD4(+) and CD8(+) T lymphocytes. Taken together, these data suggest that a naïve CNS has an intrinsic potential to induce an innate immune response that could be crucial to the outcome of the infection by determining the composition and dynamics of the adaptive immune response. Furthermore, these results establish a model for neurotropic virus infection to identify host and viral factors that contribute to invasion of the brain, the mechanism(s) whereby the adaptive immune response can clear the infection, and the role of the host innate response in these processes.

  17. Venezuelan equine encephalitis replicon particles can induce rapid protection against foot-and-mouth disease virus.

    PubMed

    Diaz-San Segundo, Fayna; Dias, Camila C A; Moraes, Mauro P; Weiss, Marcelo; Perez-Martin, Eva; Owens, Gary; Custer, Max; Kamrud, Kurt; de los Santos, Teresa; Grubman, Marvin J

    2013-05-01

    We have previously shown that delivery of the porcine type I interferon gene (poIFN-α/β) with a replication-defective human adenovirus vector (adenovirus 5 [Ad5]) can sterilely protect swine challenged with foot-and-mouth disease virus (FMDV) 1 day later. However, the need of relatively high doses of Ad5 limits the applicability of such a control strategy in the livestock industry. Venezuelan equine encephalitis virus (VEE) empty replicon particles (VRPs) can induce rapid protection of mice against either homologous or, in some cases, heterologous virus challenge. As an alternative approach to induce rapid protection against FMDV, we have examined the ability of VRPs containing either the gene for green fluorescent protein (VRP-GFP) or poIFN-α (VRP-poIFN-α) to block FMDV replication in vitro and in vivo. Pretreatment of swine or bovine cell lines with either VRP significantly inhibited subsequent infection with FMDV as early as 6 h after treatment and for at least 120 h posttreatment. Furthermore, mice pretreated with either 10(7) or 10(8) infectious units of VRP-GFP and challenged with a lethal dose of FMDV 24 h later were protected from death. Protection was induced as early as 6 h after treatment and lasted for at least 48 h and correlated with induction of an antiviral response and production of IFN-α. By 6 h after treatment several genes were upregulated, and the number of genes and the level of induction increased at 24 h. Finally, we demonstrated that the chemokine IP-10, which is induced by IFN-α and VRP-GFP, is directly involved in protection against FMDV.

  18. Replicon Particles of Venezuelan Equine Encephalitis Virus as a Reductionist Murine Model for Encephalitis▿

    PubMed Central

    Schäfer, Alexandra; Whitmore, Alan C.; Konopka, Jennifer L.; Johnston, Robert E.

    2009-01-01

    Venezuelan equine encephalitis virus (VEE) replicon particles (VRP) were used to model the initial phase of VEE-induced encephalitis in the mouse brain. VRP can target and infect cells as VEE, but VRP do not propagate beyond the first infected cell due to the absence of the structural genes. Direct intracranial inoculation of VRP into mice induced acute encephalitis with signs similar to the neuronal phase of wild-type VEE infection and other models of virus-induced encephalitis. Using the previously established VRP-mRNP tagging system, a new method to distinguish the host responses in infected cells from those in uninfected bystander cell populations, we detected a robust and rapid innate immune response in the central nervous system (CNS) by infected neurons and uninfected bystander cells. Moreover, this innate immune response in the CNS compromised blood-brain barrier integrity, created an inflammatory response, and directed an adaptive immune response characterized by proliferation and activation of microglia cells and infiltration of inflammatory monocytes, in addition to CD4+ and CD8+ T lymphocytes. Taken together, these data suggest that a naïve CNS has an intrinsic potential to induce an innate immune response that could be crucial to the outcome of the infection by determining the composition and dynamics of the adaptive immune response. Furthermore, these results establish a model for neurotropic virus infection to identify host and viral factors that contribute to invasion of the brain, the mechanism(s) whereby the adaptive immune response can clear the infection, and the role of the host innate response in these processes. PMID:19225006

  19. Venezuelan Equine Encephalitis Virus Disrupts STAT1 Signaling by Distinct Mechanisms Independent of Host Shutoff▿

    PubMed Central

    Simmons, Jason D.; White, Laura J.; Morrison, Thomas E.; Montgomery, Stephanie A.; Whitmore, Alan C.; Johnston, Robert E.; Heise, Mark T.

    2009-01-01

    Venezuelan equine encephalitis virus (VEEV) is an important human and veterinary pathogen causing sporadic epizootic outbreaks of potentially fatal encephalitis. The type I interferon (IFN) system plays a central role in controlling VEEV and other alphavirus infections, and IFN evasion is likely an important determinant of whether these viruses disseminate and cause disease within their hosts. Alphaviruses are thought to limit the induction of type I IFNs and IFN-stimulated genes by shutting off host cell macromolecular synthesis, which in the case of VEEV is partially mediated by the viral capsid protein. However, more specific strategies by which alphaviruses inhibit type I IFN signaling have not been characterized. Analyses of cells infected with VEEV and VEEV replicon particles (VRP) demonstrate that viral infection rapidly disrupts tyrosine phosphorylation and nuclear translocation of the transcription factor STAT1 in response to both IFN-β and IFN-γ. This effect was independent of host shutoff and expression of viral capsid, suggesting that VEEV uses novel mechanisms to interfere with type I and type II IFN signaling. Furthermore, at times when STAT1 activation was efficiently inhibited, VRP infection did not limit tyrosine phosphorylation of Jak1, Tyk2, or STAT2 after IFN-β treatment but did inhibit Jak1 and Jak2 activation in response to IFN-γ, suggesting that VEEV interferes with STAT1 activation by the type I and II receptor complexes through distinct mechanisms. Identification of the viral requirements for this novel STAT1 inhibition will further our understanding of alphavirus molecular pathogenesis and may provide insights into effective alphavirus-based vaccine design. PMID:19656875

  20. The Role of the Blood-Brain Barrier during Venezuelan Equine Encephalitis Virus Infection ▿

    PubMed Central

    Schäfer, Alexandra; Brooke, Christopher B.; Whitmore, Alan C.; Johnston, Robert E.

    2011-01-01

    Venezuelan equine encephalitis (VEE) virus is a mosquito-borne alphavirus associated with sporadic outbreaks in human and equid populations in the Western Hemisphere. After the bite of an infected mosquito, the virus initiates a biphasic disease: a peripheral phase with viral replication in lymphoid and myeloid tissues, followed by a neurotropic phase with infection of central nervous system (CNS) neurons, causing neuropathology and in some cases fatal encephalitis. The mechanisms allowing VEE virus to enter the CNS are currently poorly understood. Previous data have shown that the virus gains access to the CNS by infecting olfactory sensory neurons in the nasal mucosa of mice. However, at day 5 after inoculation, the infection of the brain is multifocal, indicating that virus particles are able to cross the blood-brain barrier (BBB). To better understand the role of the BBB during VEE virus infection, we used a well-characterized mouse model system. Using VEE virus replicon particles (VRP), we modeled the early events of neuroinvasion, showing that the replication of VRP in the nasal mucosa induced the opening of the BBB, allowing peripherally administered VRP to invade the brain. Peripheral VEE virus infection was characterized by a biphasic opening of the BBB. Further, inhibition of BBB opening resulted in a delayed viral neuroinvasion and pathogenesis. Overall, these results suggest that VEE virus initially enters the CNS through the olfactory pathways and initiates viral replication in the brain, which induces the opening of the BBB, allowing a second wave of invading virus from the periphery to enter the brain. PMID:21849461

  1. Sequelae of Venezuelan equine encephalitis in humans: a four year follow-up.

    PubMed

    León, C A

    1975-06-01

    The purpose of this study was the identification of possible sequelae of the infection of human individuals with Virus of Venezuelan Equine Encephalitis (VEE). Special emphasis was laid on exploring neurological, psychological and behavioural aspects and particularly on the search for a possible association of the disease with epileptic phenomena, brain damage and/or mental deficiency. A four-year period of observation was conducted on a sample of children from El Carmelo (Colombia) where an epidemic of VEE took place in 1967. A group of seven children who presented the encephalitic type of the illness and were hospitalized with symptoms of CNS involvement and a confirmed diagnosis of VEE constituted the index group. This group was compared with four control groups of children with matched demographic characteristics but separated according to whether they were ill at the time of the epidemic and whether they presented serological evidence of having been infected with VEE Virus. Evaluations were conducted at three points in time during the follow-up period and they included the following procedures: (1) Survey on personal background and behaviour (through a standard questionnaire dealing with all areas of functioning); (2) Complete paediatric examination, including a careful neurological check-up; (3) Psychological examination using intelligence tests; (4) Electro-encephalographic examination according to standard techniques, with the patient awake, asleep and under photic stimulation; (5) Bi-weekly home visits to keep a record on intercurrent illness throughout the observation period. Statistical analysis of results shows significant differences between the groups in regard to the distribution of abnormalities.

  2. A multisystem approach for development and evaluation of inactivated vaccines for Venezuelan equine encephalitis virus (VEEV).

    PubMed

    Fine, Donald L; Jenkins, Erin; Martin, Shannon S; Glass, Pamela; Parker, Michael D; Grimm, Brad

    2010-02-01

    A multisystem approach was used to assess the efficiency of several methods for inactivation of Venezuelan equine encephalitis virus (VEEV) vaccine candidates. A combination of diverse assays (plaque, in vitro cytopathology and mouse neurovirulence) was used to verify virus inactivation, along with the use of a specific ELISA to measure retention of VEEV envelope glycoprotein epitopes in the development of several inactivated VEEV candidate vaccines derived from an attenuated strain of VEEV (V3526). Incubation of V3526 aliquots at temperatures in excess of 64 degrees C for periods >30 min inactivated the virus, but substantially reduced VEEV specific monoclonal antibody binding of the inactivated material. In contrast, V3526 treated either with formalin at concentrations of 0.1% or 0.5% (v/v) for 4 or 24 h, or irradiated with 50 kGy gamma radiation rendered the virus non-infectious while retaining significant levels of monoclonal antibody binding. Loss of infectivity of both the formalin inactivated (fV3526) and gamma irradiated (gV3526) preparations was confirmed via five successive blind passages on BHK-21 cells. Similarly, loss of neurovirulence for fV3526 and gV3526 was demonstrated via intracerebral inoculation of suckling BALB/c mice. Excellent protection against subcutaneous challenge with VEEV IA/B Trinidad donkey strain was demonstrated using a two dose immunization regimen with either fV3526 or gV3526. The combination of in vitro and in vivo assays provides a practical approach to optimize manufacturing process parameters for development of other inactivated viral vaccines.

  3. Replication of twelve association studies for Huntington's disease residual age of onset in large Venezuelan kindreds.

    PubMed

    Andresen, J M; Gayán, J; Cherny, S S; Brocklebank, D; Alkorta-Aranburu, G; Addis, E A; Cardon, L R; Housman, D E; Wexler, N S

    2007-01-01

    The major determinant of age of onset in Huntington's disease is the length of the causative triplet CAG repeat. Significant variance remains, however, in residual age of onset even after repeat length is factored out. Many genetic polymorphisms have previously shown evidence of association with age of onset of Huntington's disease in several different populations. To replicate these genetic association tests in 443 affected people from a large set of kindreds from Venezuela. Previously tested polymorphisms were analysed in the HD gene itself (HD), the GluR6 kainate glutamate receptor (GRIK2), apolipoprotein E (APOE), the transcriptional coactivator CA150 (TCERG1), the ubiquitin carboxy-terminal hydrolase L1 (UCHL1), p53 (TP53), caspase-activated DNase (DFFB), and the NR2A and NR2B glutamate receptor subunits (GRIN2A, GRIN2B). The GRIN2A single-nucleotide polymorphism explains a small but considerable amount of additional variance in residual age of onset in our sample. The TCERG1 microsatellite shows a trend towards association but does not reach statistical significance, perhaps because of the uninformative nature of the polymorphism caused by extreme allele frequencies. We did not replicate the genetic association of any of the other genes. GRIN2A and TCERG1 may show true association with residual age of onset for Huntington's disease. The most surprising negative result is for the GRIK2 (TAA)(n) polymorphism, which has previously shown association with age of onset in four independent populations with Huntington's disease. The lack of association in the Venezuelan kindreds may be due to the extremely low frequency of the key (TAA)(16) allele in this population.

  4. Novel vaccine against Venezuelan equine encephalitis combines advantages of DNA immunization and a live attenuated vaccine.

    PubMed

    Tretyakova, Irina; Lukashevich, Igor S; Glass, Pamela; Wang, Eryu; Weaver, Scott; Pushko, Peter

    2013-02-04

    DNA vaccines combine remarkable genetic and chemical stability with proven safety and efficacy in animal models, while remaining less immunogenic in humans. In contrast, live-attenuated vaccines have the advantage of inducing rapid, robust, long-term immunity after a single-dose vaccination. Here we describe novel iDNA vaccine technology that is based on an infectious DNA platform and combines advantages of DNA and live attenuated vaccines. We applied this technology for vaccination against infection with Venezuelan equine encephalitis virus (VEEV), an alphavirus from the Togaviridae family. The iDNA vaccine is based on transcription of the full-length genomic RNA of the TC-83 live-attenuated virus from plasmid DNA in vivo. The in vivo-generated viral RNA initiates limited replication of the vaccine virus, which in turn leads to efficient immunization. This technology allows the plasmid DNA to launch a live-attenuated vaccine in vitro or in vivo. Less than 10 ng of pTC83 iDNA encoding the full-length genomic RNA of the TC-83 vaccine strain initiated replication of the vaccine virus in vitro. In order to evaluate this approach in vivo, BALB/c mice were vaccinated with a single dose of pTC83 iDNA. After vaccination, all mice seroconverted with no adverse reactions. Four weeks after immunization, animals were challenged with the lethal epidemic strain of VEEV. All iDNA-vaccinated mice were protected from fatal disease, while all unvaccinated controls succumbed to infection and died. To our knowledge, this is the first example of launching a clinical live-attenuated vaccine from recombinant plasmid DNA in vivo.

  5. The ubiquitin proteasome system plays a role in venezuelan equine encephalitis virus infection.

    PubMed

    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.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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

  11. FACING SOUTH OF LANDSCAPING IN NORTHWESTERN PORTION OF PARK ...

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

    FACING SOUTH OF LANDSCAPING IN NORTHWESTERN PORTION OF PARK - Candler Park Historic District, Roughly bounded by Moreland, Dekalb, McLendon & Harold Avenues, Matthews Street & Clifton Terrace, Atlanta, Fulton County, GA

  12. General view of National Cemetery at former Northwestern Branch of ...

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

    General view of National Cemetery at former Northwestern Branch of the National Home for Disabled Volunteer Soldiers. View looking southeast from intersection of American War Mothers and Juneau Avenues. - Wood National Cemetery, 5000 West National Avenue, Milwaukee, Milwaukee County, WI

  13. 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.

  14. Analysis of crustal movement in the Central Andes Aconcagua area

    NASA Astrophysics Data System (ADS)

    Piñón, D. A.; Cimbaro, S. R.; Lenzano, L.; Smalley, R.; Raffo, A.

    2013-05-01

    A Continuous Operation Reference Station was installed at the top of Aconcagua Mountain (ACON) in 2006 in order to monitor the movement of the highest mountain in the Western Hemisphere. Due to adverse weather conditions, this GPS station wasn't operating consistently and in the summer of 2012 a replacement GPS station was installed at 5500 meters above sea level, also at Aconcagua Mountain (NICO). The new GPS station achieved continuous operation throughout 2012. Based on current records, the new GPS station is the highest in the world. With data collected by NICO and other GPS stations in the area over 2012, it was possible to calculate the time series of crustal movements at Aconcagua Mountain, part of the Andes Mountain Range. This paper shows the development of the calculation process based on scientific software and the analysis of crustal movements in geodetic and geophysical terms. The analysis of this data contributes concrete results regarding the development process of the crust following the earthquake of February 27, 2010 in the Maule region.

  15. Meteorological Conditions of Floods In The Chilean Andes Mountains

    NASA Astrophysics Data System (ADS)

    Vergara, J.

    Catastrophic floods occurred on mountains River during 2000 and 2001. The meteo- rological conditions of flood during the last five years have analyzed. For example, the flood of June 29 of 2000 occurred after one of extremely wettest June of the last 40 years were snowfall was 991cm in the Aconcagua Valley. Infrequently storms activ- ity generated a huge snowfall and rainfall over the Andes mountains on June of 2000 (1525mm in El Maule Valley) and the end of the unusually period, the flood was trig- gered by rising temperatures on the mountains and heavy rain (199mm in 24 hours) fall over the fresh snow on the morning of June 29 and floods wave developed and moved down along of the all river located on Central part of Chile, the foods peak was 2970.5m3/s on the El Maule basin in the morning of June 29. The regional meteoro- logical models with the hydrological forecasting was used for alert of the floods.

  16. 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.

  17. 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

  18. Nail haemorrhages in native highlanders of the Peruvian Andes

    PubMed Central

    Heath, Donald; Harris, Peter; Williams, David; Krüger, Hever

    1981-01-01

    Nail haemorrhages are of interest to the chest physician and cardiologist. While the common type in the distal part of the nail is produced by the minor trauma of daily life, the rarer form—scattered through the nail substance—appears to be related to hypoxaemia brought about by heart and lung disease. We thought it would be of interest to study a population which was naturally hypoxaemic because of living at high altitude. Accordingly we have studied the frequency and types of nail haemorrhage in Quechua Indians who are permanently exposed to the hypobaric hypoxia of the Andes. We found the haemorrhages to be common both in mestizos living on the coastal plain and in the native highlanders. They appeared to increase in frequency with altitude but were of the distal type and would thus seem to be the result of minor trauma as at sea level. However, just as in cases of cyanotic congenital heart disease at low altitude, those with exaggerated hypoxaemia and pronounced elevation of haematocrit—namely, subjects with Monge's disease (chronic mountain sickness)—had scattered haemorrhages in the nail substance. Images

  19. 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

    2013-05-07

    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.

  20. [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.

  1. 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

  2. The Grenville-age basement of the Andes

    NASA Astrophysics Data System (ADS)

    Ramos, Victor A.

    2010-01-01

    The analysis of the basement of the Andes shows the strong Grenville affinities of most of the inliers exposed in the different terranes from Colombia to Patagonia. The terranes have different histories, but most of them participated in the Rodinia supercontinent amalgamation during the Mesoproterozoic between 1200 and 1000 Ma. After Rodinia break-up some terranes were left in the Laurentian side such as Cuyania and Chilenia, while others stayed in the Gondwanan side. Some of the terranes once collided with the Amazon craton remained attached, experiencing diverse rifting episodes all along the Phanerozoic, as the Arequipa and Pampia terranes. Some other basement inliers were detached in the Neoproterozoic and amalgamated again to Gondwana in the Early Cambrian, Middle Ordovician or Permian times. A few basement inliers with Permian metamorphic ages were transferred to Gondwana after Pangea break-up from the Laurentian side. Some of them were part of the present Middle America terrane. An exceptional case is the Oaxaquia terrane that was detached from the Gondwana margin after the Early Ordovician and is now one of the main Mexican terranes that collided with Laurentia. These displacements, detachments, and amalgamations indicate a complex terrane transfer between Laurentia and Gondwana during Paleozoic times, following plate reorganizations and changes in the absolute motion of Gondwana.

  3. Structural style on southern flank of Merida Andes, Venezuela

    SciTech Connect

    Urbina, C.; Cornelio, A. )

    1993-02-01

    The Merida Andes exhibit the most complex tectonics in western Venezuela. By studying the different ages and regional distribution of rocks, we can describe some tectonic features which are of interest to oil exploration in this area. Vertical basement movements accompanied extensional tectonics from pre-Cambrian until Eocene times. For this time interval, we reconstructed diverse normal fault systems and associated subsidence. From Eocene time onwards, compressional tectonics gave origin to anticlines and reverse, thrust and back-thrust faults. Neo-tectonic movements have modified existing structures by dislocation along transcurrent fault systems. Geochemical analyses have determined the presence of hydrocarbon source rocks equivalent to the a Luna Formation of the Maracaibo Basin; seismic, surface and subsurface data prove the existence of excellent seals in the Eocene Paguey Shale. The principal problem is to determine the timing of hydrocarbon migration with respect to the timing of trap formation. It is highly probable that the sapropelic strata of the Navay Formation, equivalent to the La Luna Formation, is presently expelling hydrocarbons to traps in the Barinas Basin, under presently existing temperature-pressure conditions.

  4. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. 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.

  6. [Effect of the attenuated strain (TC-83) of Venezuelan equine encephalitis virus on nuclear transcription in rat brain cells].

    PubMed

    Valero-Fuenmayor, N; Añez, F; Teruel-López, M E

    1996-03-01

    In the present study the effect of the attenuated strain TC-83 of the Venezuelan Equine Encephalitis virus on the nuclear transcription in brain cells of rats was assessed. The transcription activity of the DNA depending RNA polymerases (types I and II) in the isolated nuclei of brain of infected rats and controls was determinated by incorporation of the (3H) UTP. Simultaneously a viral replication curve in the brain and the serum was carried out by plaque forming method in chicken embryo cell cultures. RNA polymerase I activity was only significantly reduced after 25 hours of infection, respect to control values, while polymerase II activity was progressive and significantly diminished from inicial stages of the viral infection at 10, 15, 20 y 25 hours post-infection compared to control values. The virus was not detected in the brain but after 25 hours post-infection with very low titers (< 0.7 log10 P.F.U./ml.), while the viral presence in the blood was demonstrated after a 10 hour period. Our results demonstrated a marked effect of the attenuated strain on the brain nuclear transcription, although the presence of the virus was not detected in the brain of the infected rats. This finding suggest a mechanism of action which deserves further studies to elucidate the cerebral metabolic response and the pathogenesis of the Venezuelan Equine Encephalitis infection.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  8. Seismicity and active tectonics of the Andes and the origin of the Altiplano

    NASA Technical Reports Server (NTRS)

    Molnar, P.

    1982-01-01

    Large earthquakes and active deformation on the Andes were studied. Earthquakes on the east side of the Andes were generally found to reflect east-west crustal shortening. These earthquakes seem to occur throughout the crust and do not reflect a detachment and low angle thrusting of the sedimentary cover onto the Brazilian shield. Instead they imply deformation of the basement. The rate of shortening is compatible with construction of the Andes by crustal shortening since the late Cretaceous, and the surface geology, at least qualitatively, is considered to reflect this process. Andean margins are considered to be a result of crustal shortening. The crustal shortening in the sub-Andes occurs concurrently with normal faulting at high elevations in parts of the Andes. The normal faulting is associated with the buoyancy of the thick crust. Crustal shortening thickens the crust and work is done against gravity. When the crustal thickness and elevation reach limiting values, the range grows laterally by further thrusting on the margins.

  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. 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.

  11. 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

  12. STS-65 Earth observation of Northern Chile & Andes Mtns taken from OV-102

    NASA Image and Video Library

    1994-07-23

    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.

  13. Cenozoic climate change as a possible cause for the rise of the Andes.

    PubMed

    Lamb, Simon; Davis, Paul

    2003-10-23

    Causal links between the rise of a large mountain range and climate have often been considered to work in one direction, with significant uplift provoking climate change. Here we propose a mechanism by which Cenozoic climate change could have caused the rise of the Andes. Based on considerations of the force balance in the South American lithosphere, we suggest that the height of, and tectonics in, the Andes are strongly controlled both by shear stresses along the plate interface in the subduction zone and by buoyancy stress contrasts between the trench and highlands, and shear stresses in the subduction zone depend on the amount of subducted sediments. We propose that the dynamics of subduction and mountain-building in this region are controlled by the processes of erosion and sediment deposition, and ultimately climate. In central South America, climate-controlled sediment starvation would then cause high shear stress, focusing the plate boundary stresses that support the high 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. 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

  16. Blastomycosis in northwestern Ontario, 2004 to 2014

    PubMed Central

    Dalcin, Daniel; Ahmed, Syed Zaki

    2015-01-01

    Blastomycosis is an invasive fungal disease caused by Blastomyces dermatitidis and the recently discovered Blastomyces gilchristii. The medical charts of 64 patients with confirmed cases of blastomycosis in northwestern Ontario during a 10-year period (2004 to 2014) were retrospectively reviewed. The number of patients diagnosed with blastomycosis in Ontario was observed to have increased substantially compared with before 1990, when blastomycosis was removed from the list of reportable diseases. Aboriginals were observed to be disproportionately represented in the patient population. Of the patients whose smoking status was known, 71.4% had a history of smoking. 59.4% of patients had underlying comorbidities and a higher comorbidity rate was observed among Aboriginal patients. The case-fatality rate from direct complications of blastomycosis disease was calculated to be 20.3%; this case-fatality rate is the highest ever to be reported in Canada and more than double that of previously published Canadian studies. The clinical characteristics of 64 patients diagnosed with blastomycosis are summarized. PMID:26600814

  17. Blastomycosis in northwestern Ontario, 2004 to 2014.

    PubMed

    Dalcin, Daniel; Ahmed, Syed Zaki

    2015-01-01

    Blastomycosis is an invasive fungal disease caused by Blastomyces dermatitidis and the recently discovered Blastomyces gilchristii. The medical charts of 64 patients with confirmed cases of blastomycosis in northwestern Ontario during a 10-year period (2004 to 2014) were retrospectively reviewed. The number of patients diagnosed with blastomycosis in Ontario was observed to have increased substantially compared with before 1990, when blastomycosis was removed from the list of reportable diseases. Aboriginals were observed to be disproportionately represented in the patient population. Of the patients whose smoking status was known, 71.4% had a history of smoking. 59.4% of patients had underlying comorbidities and a higher comorbidity rate was observed among Aboriginal patients. The case-fatality rate from direct complications of blastomycosis disease was calculated to be 20.3%; this case-fatality rate is the highest ever to be reported in Canada and more than double that of previously published Canadian studies. The clinical characteristics of 64 patients diagnosed with blastomycosis are summarized.

  18. 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.

  19. Phytoplankton in the northwestern Kara Sea

    NASA Astrophysics Data System (ADS)

    Sukhanova, I. N.; Flint, M. V.; Druzhkova, E. I.; Sazhin, A. F.; Sergeeva, V. M.

    2015-07-01

    Studies were conducted in the northwestern Kara Sea in late September of 2007 and 2011. The assessment of species, size, structure, abundance, and biomass of phytoplankton and the role of autotrophic and heterotrophic components in phytocenoses was conducted. The abundance of autotrophic micro-, nanoand picoplankton increased by more than an order of magnitude in each of the following smaller-sized groups of algae. Microphytoplankton dominated in the total biomass of autotrophic phytoplankton. The wet biomass of microphytoplankton was 2.5 times higher than the wet biomass of nanophytoplankton and 5 times higher than that of picoplankton. Nanophytoplankton dominated in abundance and biomass in the heterotrophic component of phytoplankton. The ratio of the total abundance of autotrophic and heterotrophic phytotoplankton was 7: 1, the ratio of the wet biomass of the both groups was 2.5: 1, and the proportion of the carbon biomass was 2: 1. Three biotopes were distinguished in the area of the outer shelf, the continental slope, and the deepwater area adjacent to the St. Anna Trough, which differed in composition and quantitative characteristics of phytocenoses. Frontal zones dividing the biotopes are characterized by high phytoplankton biomass and the dominance of diatoms in the community (more than 40% of the total biomass), which indicates the local availability of "new" nutrients for planktonic algae.

  20. Tracking Northwestern Pacific typhoon using seismic data

    NASA Astrophysics Data System (ADS)

    Lee, Woo-Dong; Kang, Tae-Seob

    2017-04-01

    The ambient seismic data recorded on Korean Seismic array network (KSRS) are investigated to analyze (1) to trace typhoons in the Pacific Ocean and (2) to investigate the seismic phases comprising the seismic noise fields. Super typhoons (equivalent to category 4 hurricane) in Northwestern Pacifics were selected for this study. They were selected on the basis of their strength and wide azimuthal coverage from the seismic array. To trace source area of seismic noise generated by typhoons, CLEAN f-k analysis was applied to the KSRS data to estimate the direction of seismic energy of the 0.2-0.7 Hz noise field (DF microseisms). These estimated back azimuths by the CLEAN technique show good agreement with the known values to the centers of the NW Pacific typhoons. This clearly indicates that these typhoons were responsible source of microseisms during their passing. The seismic phases in our DF microseism band are investigated with the apparent velocities from our method. The estimated velocity range indicates that the ambient seismic noise in the frequency range propagates in mostly fundamental and first few higher modes.

  1. Northwestern Mexico as photographed from Skylab

    NASA Image and Video Library

    1975-01-27

    SL4-142-4548 (27 Jan. 1974) --- An oblique view of northwestern Mexico, as photographed from the Skylab space station in Earth orbit by one of the Skylab 4 crewmen. The camera used was a hand-held 70mm Hasselblad, with SO-368 medium-speed Ektachrome film. This photograph was taken on a sweep down the coast to document the fault patterns of southern California and northwest Mexico. SL4-142-4532 gives an excellent overview of the entire region. The specific reason for this picture was an attempt to see if the Agua Blanca Fault in Baja California extends to the east toward the Gulf of California. Several attempts were made by the Skylab 4 crew to visually detect such an extension, but none was found. The report was that the fault disappeared into an area of sand and heavily eroded material that obscured any feature that might be present deeper. This area of sand and loose material is the light-colored area in the center of Baja at the extreme north part of the photograph. In addition to this geology the Pinacate volcanic field in Sonora, the sand dunes in Sonora, and the sediment flow patterns of the Colorado River entering the Gulf are additional areas of study utilizing this photograph. Photo credit: NASA

  2. Modern dust aerosol availability in northwestern China.

    PubMed

    Wang, Xunming; Cheng, Hong; Che, Huizheng; Sun, Jimin; Lu, Huayu; Qiang, Mingrui; Hua, Ting; Zhu, Bingqi; Li, Hui; Ma, Wenyong; Lang, Lili; Jiao, Linlin; Li, Danfeng

    2017-08-18

    The sources of modern dust aerosols and their emission magnitudes are fundamental for linking dust with climate and environment. Using field sample data, wind tunnel experiments and statistical analysis, we determined the contributions of wadis, gobi (stony desert), lakebeds, riverbeds, and interdunes to modern dust aerosol availability in the three important potential dust sources including the Tarim Basin, Qaidam Basin, and Ala Shan Plateau of China. The results show that riverbeds are the dominant landscape for modern dust aerosol availabilities in the Qaidam Basin, while wadis, gobi, and interdunes are the main landscapes over the Ala Shan Plateau and Tarim Basin. The Ala Shan Plateau and Tarim Basin are potential dust sources in northwestern China, while the Qaidam Basin is not a major source of the modern dust aerosols nowadays, and it is not acting in a significant way to the Loess Plateau presently. Moreover, most of modern dust aerosol emissions from China originated from aeolian processes with low intensities rather than from major dust events.

  3. Glacier surface mass balance and freshwater runoff modeling for the entire Andes Cordillera

    NASA Astrophysics Data System (ADS)

    Mernild, Sebastian H.; Liston, Glen E.; Yde, Jacob C.

    2017-04-01

    Glacier surface mass balance (SMB) observations for the Andes Cordillera are limited and, therefore, estimates of the SMB contribution from South America to sea-level rise are highly uncertain. Here, we simulate meteorological, snow, glacier surface, and hydrological runoff conditions and trends for the Andes Cordillera (1979/80-2013/14), covering the tropical latitudes in the north down to the sub-polar latitudes in the far south, including the Northern Patagonia Ice Field (NPI) and Southern Patagonia Ice Field (SPI). SnowModel - a fully integrated energy balance, blowing-snow distribution, multi-layer snowpack, and runoff routing model - was used to simulate glacier SMBs for the Andes Cordillera. The Randolph Glacier Inventory and NASA Modern-Era Retrospective Analysis for Research and Applications products, downscaled in SnowModel, allowed us to conduct relatively high-resolution simulations. The simulated glacier SMBs were verified against independent directly-observed and satellite gravimetry and altimetry-derived SMB, indicating a good statistical agreement. For glaciers in the Andes Cordillera, the 35-year mean annual SMB was found to be -1.13 m water equivalent. For both NPI and SPI, the mean SMB was positive (where calving is the likely reason for explaining why geodetic estimates are negative). Further, the spatio-temporal freshwater river runoff patterns from individual basins, including their runoff magnitude and change, were simulated. For the Andes Cordillera rivers draining to the Pacific Ocean, 86% of the simulated runoff originated from rain, 12% from snowmelt, and 2% from ice melt, whereas, for example, for Chile, the water-source distribution was 69, 24, and 7%, respectively. Along the Andes Cordillera, the 35-year mean basin outlet-specific runoff (L s-1 km-2) showed a characteristic regional hourglass shape pattern with highest runoff in both Colombia and Ecuador and in Patagonia, and lowest runoff in the Atacama Desert area.

  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. Characterization of enzootic foci of Venezuelan equine encephalitis virus in western Venezuela.

    PubMed

    Barrera, R; Torres, N; Freier, J E; Navarro, J C; García, C Z; Salas, R; Vasquez, C; Weaver, S C

    2001-01-01

    The distribution of the sylvatic subtype ID Venezuelan equine encephalitis (VEE) viruses in the lowland tropical forests of western Venezuela was investigated using remote sensing and geographic information system technologies. Landsat 5 Thematic Mapper satellite imagery was used to study the reflectance patterns of VEE endemic foci and to identify other locations with similar reflectance patterns. Enzootic VEE virus variants isolated during this study are the closest genetic relatives of the epizootic viruses that emerged in western Venezuela during 1992-1993. VEE virus surveillance was conducted by exposing sentinel hamsters to mosquito bites and trapping wild vertebrates in seven forests identified and located by means of the satellite image. We isolated VEE viruses from 48 of a total of 1,363 sentinel hamsters in two of the forests on six occasions, in both dry and wet seasons. None of the 12 small vertebrates captured in 8,190 trap-nights showed signs of previous VEE virus infection. The satellite image was classified into 13 validated classes of land use/vegetation using unsupervised and supervised techniques. Data derived from the image consisted of the raw digital values of near- and mid-infrared bands 4, 5, and 7, derived Tasseled Cap indices of wetness, greenness, and brightness, and the Normalized Difference Vegetation Index. Digitized maps provided ancillary data of elevation and soil geomorphology. Image enhancement was applied using Principal Component Analysis. A digital layer of roads together with georeferenced images was used to locate the study sites. A cluster analysis using the above data revealed two main groups of dense forests separated by spectral properties, altitude, and soil geomorphology. Virus was isolated more frequently from the forest type identified on flat flood plains of main rivers rather than the forest type found on the rolling hills of the study area. The spatial analysis suggests that mosquitoes carrying the enzootic viruses

  6. 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.

  7. [Carotenogenesis of five strains of the algae Dunaliella sp. (Chlorophyceae) isolated from Venezuelan hypersaline lagoons].

    PubMed

    Guevara, Miguel; Lodeiros, César; Gómez, Olga; Lemus, Nathalie; Núñez, Paulino; Romero, Lolymar; Vásquez, Aléikar; Rosales, Néstor

    2005-01-01

    We evaluated discontinuous cultures (Algal medium at 0.5 mM of NaNO3, and 27% NaCI) of five strains of Dunaliella sp. isolated from Venezuelan hypersaline lagoons (Araya, Coche, Peonia, Cumaraguas. and Boca Chica) and one strain from a reference collection (Dunaliella salina, LB1644). Cultures were maintained to 25+/-1 degrees C, with constant aeration, photoperiod 12:12, and two light intensities (195 and 390 microE.m(-2).s(-1)) during 30 days. Cell count was recorded on a daily basis using a Neubaüer camera. Totals of chlorophyll a and carotenoids were measured at the end of the experiment. The largest cellular densities were measured during the smallest light intensities. The strain with the largest cellular density was isolated from Boca Chica (8 xl0(6) and 2.5 xl0(6) cel.ml(-1) a 390 and 195microE.m(-2).s(-1), respectively). The increment of light intensity produced a significant reduction of growth rates in all strains. Totals of carotenoids by volume were as large as 390 microE.m(-2).s(-1). Strains LB 1644, from Coche and Araya were those that produced the largest amount of carotenoids (38.4; 32.8 and 21.0 microg.ml(-1), respectively). Differences total carotenoids by cell between treatments were significant. The largest concentration was 390 microE.m(-2).s(-1). The strains LB 1644 and Coche produced the highest values of carotenes (137.14 and 106.06 pg.cel(-1), respectively). Differences in the relation carotenoid:chlorophyll a between the strains at various light intensities was significant. Strains LB1644 presented the largest value of the relation carotenoids:chlorophyll a (20:1) at 195 microE.m(-2).s(-1). No significant differences were detected in the strain Coche (15:1). All the other strains showed relations lower than one. Our results suggest that the strains of Coche and Araya show potential to be used in the biotechnology of carotenoids production.

  8. Reply to the Comment on "Sandstone caves on Venezuelan tepuis: Return to pseudokarst?"

    NASA Astrophysics Data System (ADS)

    Aubrecht, R.; Lánczos, T.; Gregor, M.; Schlögl, J.; Šmída, B.; Liščák, P.; Brewer-Carías, Ch.; Vlček, L.

    2013-09-01

    In Aubrecht et al. (2011) we brought new data showing that the arenitic caves in the Venezuelan tepuis did not necessarily originate through quartz cement dissolution ('arenization') but the main portion of the caves originated because of poor lithification prior to erosion. An additional important process is lateritization which is responsible for at least 30% of the caves' volume. Sauro et al. (2012) in their comment support the 'arenization' theory (quartz cement dissolution) and provide several arguments against some points of our research. Their main objections and arguments relate to the following topics: 1) the validity of the arenization theory, 2) the origin and importance of the 'finger-flow' pillars, 3) the importance of the Schmidt hammer measurements and, 4) metamorphism of the Matauí Formation. In our reply we present further documentation that: The quartz cement dissolution theory of cave evolution was far less documented petrographically than the new theory presented by us. Although the presence of quartz dissolution is evident, there is no current evidence that it is widespread or that it plays a trigger role. Many of the presented examples of corrosion on quartz grains could have been caused by local alkalization. In addition, the hydrogeochemical data presented in the comment to support the 'arenization' theory do not in fact contradict our speleogenetic interpretations. 'Finger-flow' pillars are speleogenetic indicators and not speleogenetic factors. Their absence in some caves provides no evidence against our theory. Schmidt hammer measurements only objectivize the data on contrasting hardness in the Matauí Formation beds. They do not say anything about the origin of this difference. The arguments of Sauro et al. (2012) involve the metamorphic overprint of the Matauí Formation shown by the presence of pyrophyllite and quartz mobilizations. Because quartz mobilization also occurs in hypergenic conditions, it may be neglected as a metamorphic

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

    PubMed Central

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

    2017-01-01

    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, 475NVCWAK480, which differs from papain’s (CGS25CWAFS), and the enzyme lacks a transition state (TS) stabilizing residue homologous to Q19 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, each conformer 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 reductions 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 Eastern Respiratory virus (MERS). Mutation of another motif residue, K480A, led to a 9-fold decrease in kcat

  10. Engineered Mesenchymal Cells Improve Passive Immune Protection Against Lethal Venezuelan Equine Encephalitis Virus Exposure.

    PubMed

    Braid, Lorena R; Hu, Wei-Gang; Davies, John E; Nagata, Les P

    2016-08-01

    : Mesenchymal stromal cells (MSCs) are being exploited as gene delivery vectors for various disease and injury therapies. We provide proof-of-concept that engineered MSCs can provide a useful, effective platform for protection against infectious disease. Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne pathogen affecting humans and equines and can be used in bio-warfare. No licensed vaccine or antiviral agent currently exists to combat VEEV infection in humans. Direct antibody administration (passive immunity) is an effective, but short-lived, method of providing immediate protection against a pathogen. We compared the protective efficacy of human umbilical cord perivascular cells (HUCPVCs; a rich source of MSCs), engineered with a transgene encoding a humanized VEEV-neutralizing antibody (anti-VEEV), to the purified antibody. In athymic mice, the anti-VEEV antibody had a half-life of 3.7 days, limiting protection to 2 or 3 days after administration. In contrast, engineered HUCPVCs generated protective anti-VEEV serum titers for 21-38 days after a single intramuscular injection. At 109 days after transplantation, 10% of the mice still had circulating anti-VEEV antibody. The mice were protected against exposure to a lethal dose of VEEV by an intramuscular pretreatment injection with engineered HUCPVCs 24 hours or 10 days before exposure, demonstrating both rapid and prolonged immune protection. The present study is the first to describe engineered MSCs as gene delivery vehicles for passive immunity and supports their utility as antibody delivery vehicles for improved, single-dose prophylaxis against endemic and intentionally disseminated pathogens. Direct injection of monoclonal antibodies (mAbs) is an important strategy to immediately protect the recipient from a pathogen. This strategy is critical during natural outbreaks or after the intentional release of bio-weapons. Vaccines require weeks to become effective, which is not practical for first

  11. 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

  12. Long-term carbon accumulation in Andes peatlands

    NASA Astrophysics Data System (ADS)

    Huaman, Yizet; Moreira-turq, Patricia; Willems, Bram; Espinoza, Raul; Turq, Bruno; Apaéstegui, James; Llanos, Romina

    2017-04-01

    High-altitude peatlands of the Andes still remain relatively unexplored since most of the studies on carbon capture in tropical soils have focused on peatlands in low altitude areas, leaving aside the importance of the study of high mountain wetlands, currently called "bofedales" located between 3000 and 5000 masl, covering most of the Andes mountains in South America. These peatlands in turn may also represent important paleoclimatic records. In this study, we investigated three peatland cores (APA-01, APA2-01, and APA2-02) at different altitudes (4210 m, 4420 m and 4432 m, respectively) in high Andean Peatlands of southern Peru. The peatland studied is located at the headwater basin Cachi River, in the town of Ayacucho, Peru. The aim of this study was to evaluate the role played by past climatic changes on the peatlands carbon accumulation. Each core was sectioned centimeter by centimeter and sub samples (n = 31) were collected for radiocarbon dating by AMS (acceleration mass spectrometer) and were used to create a sedimentological model based on the program Clam2.2R. The concentrations of carbon and nitrogen were determined from a C / H / N elemental analyzer and the stable carbon and nitrogen isotopes (δ13C and δ15N) were also analyzed. The bulk density was determined based on the volume occupied by the sediment (g /cm3). Finally, the carbon accumulation rate (gC m-2año-1) was determined. The three cores were characterized by two sedimentary units, the results present in the first sedimentary unit of APA01 an average long-term carbon accumulation rate of 59 gC m-2año-1, APA2-01 with 32 gC m-2año-1 and finally APA2-02 with 24 gC m-2año-1; for the second sedimentary unit we have: APA01 on average 17 gC m-2año-1, APA2-01 with 33 gC m-2año-1 and finally APA2-02 with 49 gC m-2año-1. In conclusion, we can say that the carbon accumulation rate for the first sedimentary unit of the three cores decreases as the altitude increases; on the other hand, we have the

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. The Little Ice Age in the tropical Andes

    NASA Astrophysics Data System (ADS)

    Jomelli, V.; Cooley, D.; Naveau, P.; Rabatel, A.

    2003-12-01

    The period known as the Little Ice Age, from the 17th to the 19th century, brought a cooling of around 0.5 degrees Celsius as well as varyingly humid episodes Eurasia and North America. Because of a lack of long paleoclimatic time series in the tropical Andes, it is still unclear if similar cooling occurred over these tropical and Southern Hemisphere regions. Furthermore, if changes did take place, it is currently not well established if they were temporally synchronous or shifted with respect of the variations in the Northern Hemisphere or the globe. To look into this important climatic question and for advancing our understanding of the past climate links between the tropics and higher latitudes, 25 glaciers located in Bolivia and in Peru were carefully selected. Glacial activity and environmental changes were analyzed using lichenometry. Largest lichen diameters were measured in the different glacial basins. To better analyze these maximum diameters and to more appropriately represent uncertainty and the character of this collected data, age estimates of the different moraine systems were derived using extreme value theory rather than the traditional averaging. The results reveal two particular phases of glacier growth, 1550-1600 and 1800-1850. These two phases have also been identified in other proxy records, such as ice-cores and documentary data (particularly from church chronicles). In order to understand the climatic changes that could have contributed to the glacial variations, a simple model based on both precipitations and temperatures is applied to estimate mass balance questions in the basins. A cooling of the order of 0.5 C seems to be the most consistent with the data. Finally, these findings are compared with the better-known histories of Northern Hemisphere mid-latitude glaciers.

  19. Evolution of Irruputuncu volcano, Central Andes, northern Chile

    NASA Astrophysics Data System (ADS)

    Rodríguez, I.; Roche, O.; Moune, S.; Aguilera, F.; Campos, E.; Pizarro, M.

    2015-11-01

    The Irruputuncu is an active volcano located in northern Chile within the Central Andean Volcanic Zone (CAVZ) and that has produced andesitic to trachy-andesitic magmas over the last ˜258 ± 49 ka. We report petrographical and geochemical data, new geochronological ages and for the first time a detailed geological map representing the eruptive products generated by the Irruputuncu volcano. The detailed study on the volcanic products allows us to establish a temporal evolution of the edifice. We propose that the Irruputuncu volcanic history can be divided in two stages, both dominated by effusive activity: Irruputuncu I and II. The oldest identified products that mark the beginning of Irruputuncu I are small-volume pyroclastic flow deposits generated during an explosive phase that may have been triggered by magma injection as suggested by mingling features in the clasts. This event was followed by generation of large lava flows and the edifice grew until destabilization of its SW flank through the generation of a debris avalanche, which ended Irruputuncu I. New effusive activity generated lavas flows to the NW at the beginning of Irruputuncu II. In the meantime, lava domes that grew in the summit were destabilized, as shown by two well-preserved block-and-ash flow deposits. The first phase of dome collapse, in particular, generated highly mobile pyroclastic flows that propagated up to ˜8 km from their source on gentle slopes as low as 11° in distal areas. The actual activity is characterized by deposition of sulfur and permanent gas emissions, producing a gas plume that reaches 200 m above the crater. The maximum volume of this volcanic system is of ˜4 km3, being one of the smallest active volcano of Central Andes.

  20. Future water resource availability under changing climate in Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Kinouchi, T.; Mendoza, J.

    2016-12-01

    In Bolivian Andes, retreats of tropical glaciers are rapid, thus water resources currently available from glacierized catchments for drinking, agriculture, industry and hydropower would be changed in its volume and variations due to changing climate. Water resources in La Paz and El Alto, the capital city areas of Bolivia, strongly depend on the runoff from partially glacierized catchments located in the Cordillera Real, which is a combined contribution of surface and subsurface flow from glacierized and non-glacierized areas due to rainfall, snow melt and glacier melt. To predict the long-term availability of water resources for the capital city areas, we applied a semi-distributed conceptual glacio-hydrological model that considers various runoff pathways from partially glacierized high-altitudinal catchments located in the outer tropics under future climate conditions based on the two GCM outputs (MRI-AGCM and INGV-ECHAM4) with bias corrected by reanalysis data (ERA-INTERIM) and downscaled to our target area using the data monitored at several weather stations. The model was applied to the watershed from which current water resources for La Paz and El Alto are supplied, and eight additional catchments that are considered to be potentially effective in compensating reduced runoff from the current water resource area. As a result, we found that the current water resource area cannot support the demand due to glowing population and the decrease of runoff towards the future. We indicated that the partially-glacierized catchments located in the vicinity of the current water resource catchment can be exploited as additional water resources to compensate the potential shortage in water supply predicted for the middle of this century.

  1. 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.

  2. 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.

  3. 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.

  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. Altiplano of the Central Andes as seen from STS-66 shuttle Atlantis

    NASA Image and Video Library

    1994-11-14

    This photograph captures the exotic volcanic terrain of the Altiplano of the Central Andes. Some of the remarkable details include the west-pointing wind streaks, resulting from fine dust being transported across the Andes by high winds; paleto (old) shorelines along the margins of the salars (or dry lake beds), recording the changes in water levels on the high Altiplano; beautiful alluvial fans emptying onto some of the salars; and the hundreds of volcanic land forms which can be mapped and interpreted to help decipher the volcanic history of the region.

  6. 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.

  7. Kinematic history of the retroarc thrust belt in the central Andes of Argentina at 24-25°S: significant Andean shortening and sporadic foreland-ward deformation propagation

    NASA Astrophysics Data System (ADS)

    Pearson, D. M.; Kapp, P. A.; Decelles, P. G.; Reiners, P. W.

    2009-12-01

    The southward along-strike transition from major thin-skinned shortening of Bolivia to the significantly lower magnitude of thick-skinned shortening in northwestern Argentina has often been attributed to the presence of a thick mid to late Paleozoic section in Bolivia relative to a thin group of correlative rocks in northwestern Argentina that were affected by significant Cretaceous rifting. Despite the Andes being regarded as an archetype of ocean-continent convergence, the northwestern Argentine Andes have remained enigmatic in a structural and tectonic context. This study integrates regional geological mapping, structural analysis, and geo- and thermochronology from the Salta province of northwestern Argentina. Geological mapping in the Cachi range at ~25° S latitude revealed the presence of an ~60° west-dipping package of rocks, passing from low grade phyllites in the eastern part of the range into cordierite-bearing, anatectic and arc-related rocks in the core of the range (one anatectic pluton yielded a U/Pb zircon age of 488 ± 10 Ma). Detrital zircons record U-Pb ages demonstrating that the highest-grade, structurally highest rocks are the oldest (maximum depositional age (MDA) ~548 Ma), rocks at structurally lower levels are younger (MDA ~538 Ma), whereas the structurally lowest rocks are the youngest (MDA ~523 Ma). Double dating some of these same zircons using the low temperature U-Th/He system indicates that at least 6-8 km of Miocene (15.7 ± 0.4 Ma) exhumation occurred in the core of the range at this time, yet exhumation at the eastern range margin was insufficient to reset zircons. U/Pb zircon ages from a tuff within growth strata in the footwall of a major thrust fault ~50 km east of Cachi demonstrate that shortening was ongoing there at 9.4 ± 0.4 Ma, yielding a propagation rate of the thrust belt of ~8 km/Ma. Since ~9 Ma, deformation has jumped ~150 km eastward to the Santa Barbara ranges, yielding an average rate of >30 km/Ma. Many thrust

  8. Aerosol Optical Properties over Northwestern European Seas

    NASA Astrophysics Data System (ADS)

    Avgousta Floutsi, Athina; Korras Carraca, Marios Bruno; Matsoukas, Christos; Riva, Riccardo; Biskos, George

    2017-04-01

    Atmospheric aerosols, both natural and anthropogenic, can affect the regional and global climate through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. In order to quantify these effects it is necessary to determine the aerosol load. An effective way to do this is by measuring the aerosol optical depth (AOD). Besides AOD, the Fine mode Fraction (AOD of particles smaller than 1 μm / total AOD, FF) is a useful parameter for the characterization of the aerosol and provides a good proxy for particle size. In this study, we investigate the spatial and temporal variability of the AOD and FF over the Western and Northwestern European Seas (43° N - 67° N, 10° W - 31° E), where significant sources of both natural and anthropogenic particles are located. Anthropogenic particles (mostly fine mode) originate from ship activity, or from urban-industrial and biomass-burning processes in the European countries. The natural, coarse mode particles are primarily sea salt. The study is performed using Collection 006 Level-3 mean daily aerosol data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board Aqua satellite, available in 1° × 1° resolution (ca. 100 km × 100 km) over the period 2002- 2014. Our results indicate significant spatial variability of the aerosol load over the study region. The highest AOD values (up to 0.32 on annual level) are observed over the English Channel and the coasts of the Netherlands and Germany. In these regions the highest FF values are also observed (up to 0.77), indicating a relatively large contribution of anthropogenic particles to the aerosol load. Offshore, both AOD and FF are lower compared to coastal regions, indicating the predominance of maritime aerosols (sea salt). The data also show a clear seasonal cycle, with larger aerosol load during spring and summer (AOD up to 0.60), and lower during autumn and winter (AOD up to 0.30). A similar

  9. Northwestern Argentina as seen from the Apollo 7 spacecraft

    NASA Image and Video Library

    1968-10-21

    AS07-04-1593 (21 Oct. 1968) --- This Earth observation photograph shows Argentina, Chile, Bolivia, Salar de Atacama, the Andes Mountains, and Gran Chaco. The coordinates for the center of this photograph are 23.00 degrees south and 67.30 degrees west, taken at an altitude of 175 miles during the 154th revolution around Earth. The crew consisted of astronauts Walter M. Schirra, Donn F. Eisele and Walter Cunningham.

  10. 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.

  11. Vector competence of Culex (Melanoconion) taeniopus for equine-virulent subtype IE strains of Venezuelan equine encephalitis virus.

    PubMed

    Deardorff, Eleanor R; Weaver, Scott C

    2010-06-01

    The mosquito Culex (Melanoconion) taeniopus is a proven vector of enzootic Venezuelan equine encephalitis virus (VEEV) subtype IE in Central America. It has been shown to be highly susceptible to infection by this subtype, and conversely to be highly refractory to infection by other VEEV subtypes. During the 1990s in southern coastal Mexico, two VEE epizootics in horses were attributed to subtype IE VEEV. These outbreaks were associated with VEEV strains with an altered infection phenotype for the epizootic mosquito vector, Aedes (Ochlerotatus) taeniorhynchus. To determine the infectivity for the enzootic vector, Culex taeniopus, mosquitoes from a recently established colony were orally exposed to VEEV strains from the outbreak. The equine-virulent strains exhibited high infectivity and transmission potential comparable to a traditional enzootic subtype IE VEEV strain. Thus, subtype IE VEEV strains in Chiapas are able to efficiently infect enzootic and epizootic vectors and cause morbidity and mortality in horses.

  12. Cataract and pterygium surgery results in Venezuelan patients treated in the Misión Milagro program.

    PubMed

    Triana, Idalia; Socarrás, Oaris Angeles de Los; Rondón, Nelsis

    2012-07-01

    An intervention to address vision loss was carried out in 2008 in Táchira, Venezuela, by health teams of the joint Cuban-Venezuelan initiative known as Misión Milagro. It included active case identification of patients with ophthalmologic conditions and, where warranted, surgery, followup, rehabilitation and medical discharge. From a universe of 345 patients aged ≥18 years with ophthalmologic conditions found, 210 were selected for cataract or pterygium surgery. Of cataract patients, 55.2% recovered optimal vision within three months after surgery, as did 90.9% of those with pterygium; frequency of complications was 15.4% in cataract patients and 41.7% in pterygium patients. The intervention was considered successful, although many patients' low-income status required premature postoperative return to their jobs and other labors, a factor considered detrimental to optimal recovery.

  13. Vector Competence of Culex (Melanoconion) taeniopus for Equine-Virulent Subtype IE Strains of Venezuelan Equine Encephalitis Virus

    PubMed Central

    Deardorff, Eleanor R.; Weaver, Scott C.

    2010-01-01

    The mosquito Culex (Melanoconion) taeniopus is a proven vector of enzootic Venezuelan equine encephalitis virus (VEEV) subtype IE in Central America. It has been shown to be highly susceptible to infection by this subtype, and conversely to be highly refractory to infection by other VEEV subtypes. During the 1990s in southern coastal Mexico, two VEE epizootics in horses were attributed to subtype IE VEEV. These outbreaks were associated with VEEV strains with an altered infection phenotype for the epizootic mosquito vector, Aedes (Ochlerotatus) taeniorhynchus. To determine the infectivity for the enzootic vector, Culex taeniopus, mosquitoes from a recently established colony were orally exposed to VEEV strains from the outbreak. The equine-virulent strains exhibited high infectivity and transmission potential comparable to a traditional enzootic subtype IE VEEV strain. Thus, subtype IE VEEV strains in Chiapas are able to efficiently infect enzootic and epizootic vectors and cause morbidity and mortality in horses. PMID:20519599

  14. INDUCTION OF NEUTRALIZING ANTIBODIES TO HENDRA AND NIPAH GLYCOPROTEINS USING A VENEZUELAN EQUINE ENCEPHALITIS VIRUS IN VIVO EXPESSION SYSTEM

    PubMed Central

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

    2010-01-01

    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 (VRP) 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 development of an effective vaccine against the henipaviruses. PMID:21050901

  15. 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.

  16. Evaluation of neurovirulence and biodistribution of Venezuelan equine encephalitis replicon particles expressing herpes simplex virus type 2 glycoprotein D.

    PubMed

    Kowalski, Jacek; Adkins, Karissa; Gangolli, Seema; Ren, Jian; Arendt, Heather; DeStefano, Joanne; Obregon, Jennifer; Tummolo, Donna; Natuk, Robert J; Brown, Tom P; Parks, Christopher L; Udem, Stephen A; Long, Deborah

    2007-03-08

    The safety of a propagation-defective Venezuelan equine encephalitis virus (VEEV) replicon particle vaccine was examined in mice. After intracranial inoculation we observed approximately 5% body weight loss, modest inflammatory changes in the brain, genome replication, and foreign gene expression. These changes were transient and significantly less severe than those caused by TC-83, a live-attenuated vaccinal strain of VEEV that has been safely used to immunize military personnel and laboratory workers. Replicon particles injected intramuscularly or intravenously were detected at limited sites 3 days post-administration, and were undetectable by day 22. There was no evidence of dissemination to spinal cord or brain after systemic administration. These results demonstrate that propagation-defective VEEV replicon particles are minimally neurovirulent and lack neuroinvasive potential.

  17. Synthetic peptides of Venezuelan equine encephalomyelitis virus E2 glycoprotein. I. Immunogenic analysis and identification of a protective peptide.

    PubMed

    Hunt, A R; Johnson, A J; Roehrig, J T

    1990-12-01

    Fourteen peptides representing 67% of the extramembranal domain of the Venezuelan equine encephalomyelititis (VEE) virus E2 glycoprotein were synthesized and analyzed to determine their antigenic, immunogenic, and protective capacities. Thirteen of 14 peptides elicited antibody for the homologous peptide. Thirteen peptides elicited antiviral antibody that recognized either the Trinidad (TRD) strain of VEE virus or the TC-83 vaccine derivative, or both. Two peptides, VE2pep01(TC-83) and VE2pep01(TRD), protected significant numbers of mice from TRD virus challenge. The majority of the peptides were reactive with antisera from mice immunized with the various subtypes of VEE virus. A competition assay using antipeptide antibodies to block virus binding of anti-VEE virus monoclonal antibodies corroborated previous studies on the spatial relationship of E2 epitopes and provided evidence for a spatial overlap of the E2 amino terminus with a domain composed of residues 180-210.

  18. Equine amplification and virulence of subtype IE Venezuelan equine encephalitis viruses isolated during the 1993 and 1996 Mexican epizootics.

    PubMed

    Gonzalez-Salazar, Dante; Estrada-Franco, José G; Carrara, Anne-Sophie; Aronson, Judith F; Weaver, Scott C

    2003-02-01

    To assess the role of horses as amplification hosts during the 1993 and 1996 Mexican Venezuelan equine encephalitis (VEE) epizootics, we subcutaneously infected 10 horses by using four different equine isolates. Most horses showed little or no disease and low or nonexistent viremia. Neurologic disease developed in only 1 horse, and brain histopathologic examination showed meningeal lymphocytic infiltration, perivascular cuffing, and focal encephalitis. Three animals showed mild meningoencephalitis without clinical disease. Viral RNA was detected in the brain of several animals 12-14 days after infection. These data suggest that the duration and scope of the recent Mexican epizootics were limited by lack of equine amplification characteristic of previous, more extensive VEE outbreaks. The Mexican epizootics may have resulted from the circulation of a more equine-neurotropic, subtype IE virus strain or from increased transmission to horses due to amplification by other vertebrate hosts or transmission by more competent mosquito vectors.

  19. Equine Amplification and Virulence of Subtype IE Venezuelan Equine Encephalitis Viruses Isolated during the 1993 and 1996 Mexican Epizootics

    PubMed Central

    Gonzalez, Dante; Estrada-Franco, José G.; Carrara, Anne-Sophie; Aronson, Judith F.

    2003-01-01

    To assess the role of horses as amplification hosts during the 1993 and 1996 Mexican Venezuelan equine encephalitis (VEE) epizootics, we subcutaneously infected 10 horses by using four different equine isolates. Most horses showed little or no disease and low or nonexistent viremia. Neurologic disease developed in only 1 horse, and brain histopathologic examination showed meningeal lymphocytic infiltration, perivascular cuffing, and focalencephalitis. Three animals showed mild meningoencephalitis without clinical disease. Viral RNA was detected in the brain of several animals 12-14 days after infection. These data suggest that the duration and scope of the recent Mexican epizootics were limited by lack of equine amplification characteristic of previous, more extensive VEE outbreaks. The Mexican epizootics may have resulted from the circulation of a more equine-neurotropic, subtype IE virus strain or from increased transmission to horses due to amplification by other vertebrate hosts or transmission by more competent mosquito vectors. PMID:12603985

  20. The atypical Caribbean-Colombia oceanic plateau and its role in the deformation of the Northern Andes

    NASA Astrophysics Data System (ADS)

    Ferrari, L.; Lopez-Martinez, M.; Petrone, C. M.; Serrano, L.

    2013-05-01

    The Late Cretaceous to Early Tertiary tectono-magmatic evolution of the Northern Andes has been strongly influenced by the dextral oblique interaction of the Caribbean-Colombian oceanic plateau (CCOP) with northwestern South America. This complex interaction has resulted in several pulses of transpressional deformation and crustal accretion to the South America plate but also in a widespread deformation in the plateau itself. In this peculiar type of orogeny one of the factors controlling the deformation is the crustal structure and thus the rheological profiles of the two lithospheric sections that interact. The genesis of the CCOP has been traditionally associated to the melting of the Galapagos plume head when it impacted the Farallon plate, which is supposed to have built an unsubductable and thick crustal section. This interpretation was based on the apparent clustering of ages at ~91-89 Ma for several obducted fragments of the CCOP in northwestern South America and in the Caribbean islands. However, seismic profiles show that magmatism added a very variable amount but no more than 10 km of igneous material to the original crust of the Farallon plate, making the CCOP much more irregular than other oceanic plateaus. Recent studies of key areas of the obducted part of the CCOP contradict the notion that the plateau formed by melting of a plume head at ~ 90 Ma. Particularly, new geochronologic data and petrologic modeling from the small Gorgona Island document a magmatic activity spanning the whole Late Cretaceous (98.7±7.7 to 64.4±5 Ma) and a progressive increase in the degree of melting and melt extraction with time. Multiple magmatic pulses over several tens of Ma in small areas like Gorgona, are also recognized in other areas of the CCOP, documenting a long period of igneous activity with peaks at 74-76, 80-82, and 88-90 Ma in decreasing order of importance. Even older, Early Cretaceous ages, have been reported for fragments in Costa Rica and Curaçao. A

  1. [Fatty acids in mature breast milk from low socioeconomic levels of Venezuelan women: influence of temperature and time of storage].

    PubMed

    Bosch, Virgilio; Golfetto, Iván; Alonso, Hilda; Laurentin, Zuly; Materan, Mercedes; García, Ninoska

    2009-03-01

    Fatty acids in mature breast milk from low socioeconomic levels of Venezuelan women: influence of temperature and time of storage. Breast milk is the main food in infants from birth until six months old. It is important to know if precarious life conditions could limit some nutrients in mother's milk. The objective of this study is to evaluate the total fat and essential long chain fatty acids in mature breast milk from low socioeconomic levels in Venezuelan women. The values of total fat (3.56 +/- 1.18 g/%) are similar that reported in the literature, however the sume of LC-PUFA n-3 was 0.3 +/- 0.04% which is related whith low n-3 fatty acid maternal diet.The sume LC-PUFA n-3 contained in this study is below most of the reviewed publications. The average amount of 22:6 n-3 in breast milk offered to newborn one month old (750 ml/day) is below estimated requirements (70 mg/day). The majority of these samples provide to the infants, the amount of DHA estimated as convenient to sustain normal growth. Also it was explored how the time (8h to 24 h) and temperatura (+4 degrees C, +15 degrees C, and +25 degrees C) can affect its composition. This data will permit to select the best condiitions of sampling and storage of mother's milk in future investigations in different regions of Venezuela. Most of the breast milk fatty acids tolerate some hours at room temperature (25 degrees C) but essential long chain fatty acids are very vulnerable. We propose that, in consequence, that samples should be transported in sterile conditions in dry ice to the laboratory in a few hours and should be kept at -70 degrees C until their analysis.

  2. Association of socioeconomic stratification with plasmatic markers of lipoperoxidation and antioxidants in Venezuelan school-age children

    PubMed Central

    Bosch, Virgilio; Giacopini, Maria Isabel

    2016-01-01

    Abstract Objetive: To establish association between socioeconomic status and plasmatic markers of lipoperoxidation and antioxidants in Venezuelan school-age children from the middle-class and in critical poverty. Methods: Cross-sectional study with a sample of 114 school-age children (aged 7-9). The socioeconomic status, dietary intake of macro and micro-nutrients, weight, height, lipid profile, indicators of lipid peroxidation and enzymatic and non-enzymatic antioxidants were determined. Results: The daily average intake of energy, carbohydrates and vitamin A, and the percentage of energy obtained from carbohydrates was significantly higher in middle-class children compared to critical poverty children (p <0.05). The circulating oxidized low density lipoprotein (p <0.001) and the susceptibility of low density lipoproteins and very low density lipoproteins to oxidation in vitro (p <0.05) were significantly higher in middle-class children, while the critical poverty children showed significantly lower levels of Vitamin C and E in plasma (p <0.05). Non-enzymatic antioxidant levels were frequently deficient in both strata. The concentrations of circulating oxidized low density lipoprotein (OR: 1.09, CI 95%: 1.016-1.179; p= 0.017) and Vitamin C (OR: 3.21, CI 95%: 1.104-9.938; p= 0.032) were associated to the socioeconomic status independently of gender, family history of premature coronary artery disease, triglicerides, Vitamin C and E dietary intake and count of white blood cells. Conclusion: The socioeconomic status was associated to circulating oxidized low density lipoprotein and Vitamin C in Venezuelan school-age children, The results suggested the need to improve the dietary intake of antioxidants in both studied socioeconomic groups. PMID:28293041

  3. 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.

  4. 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. © 2013 Blackwell Publishing Ltd.

  5. 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.

  6. 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…

  7. Transboundary protected area proposals along the Southern Andes of Chile and Argentina: Status of current efforts

    Treesearch

    Peter Keller

    2007-01-01

    An evolving network of protected areas along the southern Andes of Chile and Argentina-the heart of Patagonia-are in various stages of evaluation and potential Transboundary Protected Area designations. This paper examines three such efforts. The first proposal is the North Andean-Patagonia Regional Eco-Corridor, which was the subject of a recent bilateral meeting...

  8. "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…

  9. 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…

  10. 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.

  11. Motion of continental slivers and creeping subduction in the northern Andes

    NASA Astrophysics Data System (ADS)

    Nocquet, J.-M.; Villegas-Lanza, J. C.; Chlieh, M.; Mothes, P. A.; Rolandone, F.; Jarrin, P.; Cisneros, D.; Alvarado, A.; Audin, L.; Bondoux, F.; Martin, X.; Font, Y.; Régnier, M.; Vallée, M.; Tran, T.; Beauval, C.; Maguiña Mendoza, J. M.; Martinez, W.; Tavera, H.; Yepes, H.

    2014-04-01

    Along the western margin of South America, plate convergence is accommodated by slip on the subduction interface and deformation of the overriding continent. In Chile, Bolivia, Ecuador and Colombia, continental deformation occurs mostly through the motion of discrete domains, hundreds to thousands of kilometres in scale. These continental slivers are wedged between the Nazca and stable South American plates. Here we use geodetic data to identify another large continental sliver in Peru that is about 300-400 km wide and 1,500 km long, which we call the Inca Sliver. We show that movement of the slivers parallel to the subduction trench is controlled by the obliquity of plate convergence and is linked to prominent features of the Andes Mountains. For example, the Altiplano is located at the boundary of converging slivers at the concave bend of the central Andes, and the extending Gulf of Guayaquil is located at the boundary of diverging slivers at the convex bend of the northern Andes. Motion of a few large continental slivers therefore controls the present-day deformation of nearly the entire Andes mountain range. We also show that a 1,000-km-long section of the plate interface in northern Peru and southern Ecuador slips predominantly aseismically, a behaviour that contrasts with the highly seismic neighbouring segments. The primary characteristics of this low-coupled segment are shared by ~20% of the subduction zones in the eastern Pacific Rim.

  12. 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

  13. 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…

  14. "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…

  15. Between Andes and Amazon: the genetic profile of the Arawak-speaking Yanesha.

    PubMed

    Barbieri, Chiara; Heggarty, Paul; Yang Yao, Daniele; Ferri, Gianmarco; De Fanti, Sara; Sarno, Stefania; Ciani, Graziella; Boattini, Alessio; Luiselli, Donata; Pettener, Davide

    2014-12-01

    The Yanesha are a Peruvian population who inhabit an environment transitional between the Andes and Amazonia. They present cultural traits characteristic of both regions, including in the language they speak: Yanesha belongs to the Arawak language family (which very likely originated in the Amazon/Orinoco lowlands), but has been strongly influenced by Quechua, the most widespread language family of the Andes. Given their location and cultural make-up, the Yanesha make for an ideal case study for investigating language and population dynamics across the Andes-Amazonia divide. In this study, we analyze data from high and mid-altitude Yanesha villages, both Y chromosome (17 STRs and 16 SNPs diagnostic for assigning haplogroups) and mtDNA data (control region sequences and 3 SNPs and one INDEL diagnostic for assigning haplogroups). We uncover sex-biased genetic trends that probably arose in different stages: first, a male-biased gene flow from Andean regions, genetically consistent with highland Quechua-speakers and probably dating back to Inca expansion; and second, traces of European contact consistent with Y chromosome lineages from Italy and Tyrol, in line with historically documented migrations. Most research in the history, archaeology and linguistics of South America has long been characterized by perceptions of a sharp divide between the Andes and Amazonia; our results serve as a clear case-study confirming demographic flows across that 'divide'.

  16. 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

  17. 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 the...

  18. 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 the...

  19. 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 the...

  20. 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 the...

  1. Episodic subgreenschist facies metamorphism in the Andes of Chile - is it a valid model?

    NASA Astrophysics Data System (ADS)

    Bevins, R. E.; Robinson, D.; Aguirre, L.; Vergara, M.

    2003-04-01

    The Central Andes of Chile are characterized by subgreenschist facies burial metamorphism that is reported as having developed in up to seven episodic cycles of some 40Myr duration. The main evidence in support of the model is reported as mineralogical breaks at major stratigraphic boundaries that are interpreted as documenting sharp breaks in metamorphic grade. Here we test this model by examination of the progressive secondary mineral development, reaction progress in mafic phyllosilicates, and topological variations of the low-grade assemblages in metabasites for Jurassic to Miocene sequences east of Santiago. The mafic phyllosilicates (smectite - mixed-layer chlorite/smectite - chlorite) show increasing reaction progress with stratigraphic age and there is a continuum across the main stratigraphic boundaries, such there is no offset or gap in the reaction progress at these boundaries. There are some differences in mineral assemblages between the various stratigraphic units, such as between prehnite+pumpellyite+/-laumonite or amphibole-bearing and non amphibole bearing rocks, from which contrasting subgreenschist facies can be recognised. However, consideration of the controls on mineral parageneses at subgreenschist facies conditions demonstrates that these different facies cannot be used solely as evidence of sharp breaks in metamorphic grade at unconformities, as has been reported in many previous publications for the Andes. The presently accepted model for the Central Andes, involving repeated cycles of episodic metamorphism developing in extensional basins, is, therefore, partly unfounded. Consideration of the overall tectonic evolution of this part of the Andes concurs that the burial metamorphism developed in extensional settings, but in only two events, namely in mid-late Cretaceous and Late Miocene times respectively. The results from this work suggest that the record of sharp metamorphic breaks and the episodic model of metamorphism reported for many

  2. Structure and Evolution of the Central Andes of Peru

    NASA Astrophysics Data System (ADS)

    Gonzalez, L.; Pfiffner, O. A.

    2009-04-01

    Three major units make up the Andes in Peru: (1) The Western Cordillera consists of the Cretaceous Coastal Batholith intruding Jurassic to Cretaceous volcaniclastics (Casma group) in the west, and a fold-and-thrust belt of Mesozoic sediments in the east. Eocene and Miocene volcanics (Calipuy group and equivalents) overly all of these rock types. (2) The Central Highland contains a folded Paleozoic-Mesozoic sedimentary sequence overlain by thick Quaternary deposits. A major fault puts Neoproterozoic basement rocks of the Eastern Cordillera next to these units. (3) In the Eastern Cordillera, Late Paleozoic clastic successions unconformably overly folded Early Paleozoic sediments and a Neoproterozoic basement in the east. Permian (locally Triassic) granitoids intruded these units and were affected by folding and thrusting. In the core of the Eastern Cordillera, Early Cretaceous overly Early or Late Paleozoic strata. To the west, a thrust belt of Paleozoic to Cenozoic strata forms the transition to the foreland of the Brasilian shield. The most external part of this thrust belt involves Pliocene sediments and is referred to as Subandine zone. The Coastal Batholith is internally undeformed. The adjacent fold-and-thrust belt to the east is characterized by tight, nearly isoclinal upright folds with amplitudes of up to 1000 m. At the surface only Cretaceous rocks are observed. Using balancing techniques, a detachment horizon at the base of the Lowermost Cretaceous (Goyallarisquizga group - Oyon Formation) can be proposed. Further east, folds are more open, asymmetric and east verging, Jurassic sediments appear in the cores of the anticlines. The abrupt change in style from upright tight folding in the west to more open folding in the east is explained by a primary difference in the depositional sequence, most probably associated with synsedimentary faulting. The overlying volcanics of the Calipuy group and equivalents are, in turn, only slightly folded. In the Northern

  3. Evaluation of vascular clearance as a marker for virulence of alphaviruses: disassociation of rapid clearance with low virulence of venezuelan encephalitis virus strains in guinea pigs.

    PubMed Central

    Jahrling, P B; Heisey, G B; Hesse, R A

    1977-01-01

    The concept that relates low virulence of certain alphaviruses to low viremia and efficient vascular clearance of virus was tested in guinea pigs. Previously published studies with hamsters suggested that virulent strains maintain high viremias primarily because they are cleared inefficiently from the blood. In the present study, with guinea pigs, six of six virulent strains of Venezuelan encephalitis virus were cleared inefficiently, whereas three of six nonlethal or benign virus strains were cleared rapidly. However, three other guinea pig-benign Venezuelan encephalitis virus strains cleared slowly, to produce a high viremia was correlated with inefficient growth in primary viral replication sites. Thus, the potential of some alphaviruses to produce destructive lesions may be restricted by efficient clearance of virus from the blood, whereas the growth of other benign alphavirus strains may be restricted after the virus is presented to target cells. PMID:892910

  4. Geodynamics of the northern Andes: Subductions and intracontinental deformation (Colombia)

    NASA Astrophysics Data System (ADS)

    Taboada, Alfredo; Rivera, Luis A.; Fuenzalida, AndréS.; Cisternas, Armando; Philip, Hervé; Bijwaard, Harmen; Olaya, José; Rivera, Clara

    2000-10-01

    New regional seismological data acquired in Colombia during 1993 to 1996 and tectonic field data from the Eastern Cordillera (EC) permit a reexamination of the complex geodynamics of northwestern South America. The effect of the accretion of the Baudó-Panama oceanic arc, which began 12 Myr ago, is highlighted in connection with mountain building in the EC. The Istmina and Ibagué faults in the south and the Santa Marta-Bucaramanga fault to the northeast limit an E-SE moving continental wedge. Progressive indentation of the wedge is absorbed along reverse faults located in the foothills of the Cordilleras (northward of 5°N) and transpressive deformation in the Santander Massif. Crustal seismicity in Colombia is accurately correlated with active faults showing neotectonic morphological evidences. Intermediate seismicity allows to identify a N-NE trending subduction segment beneath the EC, which plunges toward the E-SE. This subduction is interpreted as a remnant of the paleo-Caribbean plateau (PCP) as suggested by geological and tomographic profiles. The PCP shows a low-angle subduction northward of 5.2°N and is limited southward by a major E-W transpressive shear zone. Normal oceanic subduction of the Nazca plate (NP) ends abruptly at the southern limit of the Baudó Range. Northward, the NP subducts beneath the Chocó block, overlapping the southern part of the PCP. Cenozoic shortening in the EC estimated from a balanced section is ˜120 km. Stress analysis of fault slip data in the EC (northward of 4°N), indicates an ˜E-SE orientation of σ1 in agreement with the PCP subduction direction. Northward, near Bucaramanga, two stress solutions were observed: (1) a late Andean N80°E compression and (2) an early Andean NW-SE compression.

  5. 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

  6. Regional pollution potential in the northwestern United States.

    Treesearch

    Sue A. Ferguson; Miriam L. Rorig

    2003-01-01

    The potential for air pollution from industrial sources to reach wilderness areas throughout the Northwestern United States is approximated from monthly mean emissions, along with wind speeds and directions. A simple index is derived to estimate downwind concentration. Maps of pollution potential were generated for each pollution component (particulates, sulfur oxides...

  7. North Pacific warming and intense northwestern U.S. wildfires

    Treesearch

    Yongqiang Liu

    2006-01-01

    The tropical Pacific sea surface temperature (SST) anomalies such as La Nina have been an important predictor for wildfires in the southeastern and southwestern U.S. This study seeks seasonal predictors for wildfires in the northwestern U.S., a region with the most intense wildfires among various continental U.S. regions. Singular value decomposition and regression...

  8. Middle Proterozoic piggyback basin in the subsurface of northwestern Canada

    SciTech Connect

    Cook, F.A.; Clark, E.A. )

    1990-07-01

    Seismic reflection profiles from the interior platform in the northwestern Canadian Arctic show outstanding evidence for sedimentary basins formed and carried piggyback on thrust sheets during Middle Proterozoic compressional deformation. The seismic stratigraphic observations are the first documentation of a Proterozoic piggyback basin and thus also provide independent confirmation of proposed layer-parallel thrusting.

  9. Seabird Research and Monitoring Needs in Northwestern México

    Treesearch

    Lucia Alfaro Eduardo Palacios

    2005-01-01

    Seabird research in northwestern México has increased in the last 20 years, however many areas remain unexplored and seabird colony inventories are badly needed. Coastal wetlands and adjacent islands from southern Sonora through Nayarit host large colonies of pelecaniforme and other seabirds, but surveys of these areas have been limited and localized. Seabird colonies...

  10. Spotted owl roost and nest site selection in northwestern California

    Treesearch

    J.A. Blakesley; A.B. Franklin; R.J. Gutierrez

    1992-01-01

    We directly observed roost and nest site selection in a population of northern spotted owls (Strix occidentalis caurina) in northwestern California during 1985-89. Because of potential biases caused by use of radio telemetry in previous studies, we examined habitat use relative to habitat availability at a level not previously reported for spotted...

  11. 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.

  12. 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.

  13. Emergence of African swine fever virus, northwestern Iran.

    PubMed

    Rahimi, Pooneh; Sohrabi, Amir; Ashrafihelan, Javad; Edalat, Rosita; Alamdari, Mehran; Masoudi, Mohammadhossein; Mostofi, Saied; Azadmanesh, Kayhan

    2010-12-01

    In 2008, African swine fever was introduced into Georgia, after which it spread to neighboring Armenia, Azerbaijan, and the Russian Federation. That same year, PCR and sequence analysis identified African swine fever virus in samples from 3 dead female wild boars in northwestern Iran. Wild boars may serve as a reservoir.

  14. Habitat and host associations of Craterellus tubaeformis in northwestern Oregon.

    Treesearch

    M.J. Trappe

    2004-01-01

    Knowledge of the habitat and host associations of Craterellus tubaeformis (winter chanterelle) is the key to understanding the ecological characteristics needed for its conservation. In this study, a survey of forest types in northwestern Oregon for mycorrhizal associates is performed and the hypotheses that stand age and the volume of well-decayed...

  15. Effects of ugulate browsing on aspen regeneration in northwestern Wyoming

    Treesearch

    Bruce L. Smith; J. Scott Dieni; Roxane L. Rogers; Stanley H. Anderson

    2001-01-01

    Although clearcutting has been demonstrated to be an effective means to regenerate aspen, stand replacement may be retarded under conditions of intense browsing of regeneration, such as that experienced near elk feedgrounds in northwestern Wyoming. We studied the effects of ungulate browsing on regenerating aspen following clearcutting on the National Elk Refuge. Nine...

  16. 14. Interior, northwestern side of Pier G, showing the adjustable ...

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

    14. Interior, northwestern side of Pier G, showing the adjustable ramp with pulley system. The typical first floor (supporting second floor) structural unit is two 12x12-inch columns, 8x12-inch diagonal braces, 6x12-inch cushion capitals, 12x12-inch beam, and 3x14-inch joists. - Lehigh Valley Railroad, Pier G, Jersey City, Hudson County, NJ

  17. The Center for Talent Development at Northwestern University

    ERIC Educational Resources Information Center

    Olszewski-Kubilius, Paula

    2004-01-01

    During the summer and on weekends, it is not unusual to see many children, the youngest holding their parents' hands, walking to classes amongst the beautiful landscaping and old buildings of Northwestern University on Lake Michigan's shores in Evanston, Illinois. The Center for Talent Development (CTD) has been offering services and programs to…

  18. Winter prey selection of Canada lynx in northwestern Montana

    Treesearch

    John R. Squires; Leonard F. Ruggiero

    2007-01-01

    The roles that diet and prey abundance play in habitat selection of Canada lynx (Lynx canadensis) in the contiguous United States is poorly understood. From 1998-2002, we back-tracked radiocollared lynx (6 F, 9 M) for a distance of 582 km and we located 86 kills in northwestern Montana, USA. Lynx preyed on 7 species that included blue grouse (Dendragapus...

  19. Upland forest vegetation of the Ozark Mountains in Northwestern Arkansas

    Treesearch

    Steven L. Stephenson; Harold S. Adams; Cynthia D. Huebner

    2007-01-01

    Quantitative data on structure and composition of all strata of vegetation were collected from 20 study sites in the Boston Mountains Subsection of the Ozark Mountains of northwestern Arkansas in June 2004. All study sites were located at upper slope or ridgetop positions and occurred at elevations > 457 m. Oaks (Quercus spp.) were dominants in...

  20. 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…

  1. Black cherry provenances for planting in northwestern Pennsylvania

    Treesearch

    Russell S. Walters; Russell S. Walters

    1985-01-01

    After 14 years, survival of 8 of 25 planted black cherry sources is greater than 70 percent, and there are no significant differences in height. These sources offer the greater potential for planting in northwestern Pennsylvania; they include four Pennsylvania sources plus one each from Tennessee, West Virginia, Ohio, and Virginia. Planted trees did not grow better...

  2. 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…

  3. Parallel body shape divergence in the Neotropical fish genus Rhoadsia (Teleostei: Characidae) along elevational gradients of the western slopes of the Ecuadorian Andes.

    PubMed

    Malato, Grace; Shervette, Virginia R; Navarrete Amaya, Ronald; Valdiviezo Rivera, Jonathan; Nugra Salazar, Fredy; Calle Delgado, Paola; Karpan, Kirby C; Aguirre, Windsor E

    2017-01-01

    Neotropical mountain streams are important contributors of biological diversity. Two species of the characid genus Rhoadsia differing for an ecologically important morphological trait, body depth, have been described from mountain streams of the western slopes of the Andes in Ecuador. Rhoadsia altipinna is a deeper-bodied species reported from low elevations in southwestern Ecuador and northern Peru, and Rhoadsia minor is a more streamlined species that was described from high elevations (>1200 m) in the Esmeraldas drainage in northwestern Ecuador. Little is known about these species and their validity as distinct species has been questioned. In this study, we examine how their body shape varies along replicated elevational gradients in different drainages of western Ecuador using geometric morphometrics and the fineness ratio. We also use sequences of the mitochondrial cytochrome oxidase c I gene and the second intron of the S7 nuclear gene to examine whether genetic data are consistent with the existence of two species. We found that body depth varies continuously among populations within drainages as a function of elevation, and that body shape overlaps among drainages, such that low elevation populations of R. minor in the Esmeraldas drainage have similar body depths to higher elevation R. altipinna in southern drainages. Although a common general trend of declining body depth with elevation is clear, the pattern and magnitude of body shape divergence differed among drainages. Sequencing of mitochondrial and nuclear genes failed to meet strict criteria for the recognition of two species (e.g., reciprocal monophyly and deep genetic structure). However, there was a large component of genetic variation for the COI gene that segregated among drainages, indicating significant genetic divergence associated with geographic isolation. Continued research on Rhoadsia in western Ecuador may yield significant insight into adaptation and speciation in Neotropical mountain

  4. Parallel body shape divergence in the Neotropical fish genus Rhoadsia (Teleostei: Characidae) along elevational gradients of the western slopes of the Ecuadorian Andes

    PubMed Central

    Malato, Grace; Shervette, Virginia R.; Navarrete Amaya, Ronald; Valdiviezo Rivera, Jonathan; Nugra Salazar, Fredy; Calle Delgado, Paola; Karpan, Kirby C.

    2017-01-01

    Neotropical mountain streams are important contributors of biological diversity. Two species of the characid genus Rhoadsia differing for an ecologically important morphological trait, body depth, have been described from mountain streams of the western slopes of the Andes in Ecuador. Rhoadsia altipinna is a deeper-bodied species reported from low elevations in southwestern Ecuador and northern Peru, and Rhoadsia minor is a more streamlined species that was described from high elevations (>1200 m) in the Esmeraldas drainage in northwestern Ecuador. Little is known about these species and their validity as distinct species has been questioned. In this study, we examine how their body shape varies along replicated elevational gradients in different drainages of western Ecuador using geometric morphometrics and the fineness ratio. We also use sequences of the mitochondrial cytochrome oxidase c I gene and the second intron of the S7 nuclear gene to examine whether genetic data are consistent with the existence of two species. We found that body depth varies continuously among populations within drainages as a function of elevation, and that body shape overlaps among drainages, such that low elevation populations of R. minor in the Esmeraldas drainage have similar body depths to higher elevation R. altipinna in southern drainages. Although a common general trend of declining body depth with elevation is clear, the pattern and magnitude of body shape divergence differed among drainages. Sequencing of mitochondrial and nuclear genes failed to meet strict criteria for the recognition of two species (e.g., reciprocal monophyly and deep genetic structure). However, there was a large component of genetic variation for the COI gene that segregated among drainages, indicating significant genetic divergence associated with geographic isolation. Continued research on Rhoadsia in western Ecuador may yield significant insight into adaptation and speciation in Neotropical mountain

  5. 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.

  6. 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

  7. Volcanological evolution of Paniri volcano, Central Andes, northern Chile

    NASA Astrophysics Data System (ADS)

    Lazcano, J.; Godoy, B.; Aguilera, F.; Wilke, H.

    2012-12-01

    San Pedro-Linzor volcanic chain (SPLVC) is located between 21°45'S-22°15'S, in the Recent volcanic arc of Central Andes. This volcanic chain comprises several volcanic edifices and dacitic domes, with a total lenght of ~65 km. Volcanic structures distributed in SPLVC show a NW-SE trending orientation and have been been built over Miocene ignimbrite fields. Paniri volcano (5946 m a.s.l.) is a composite stratovolcano located in SPLVC, and distributes southwards San Pedro - San Pablo volcanic complex, at the northern side of Chao Dacite. In this work, the volcanological evolution of Paniri is presented. This volcanic edifice is constituted by two cones, generated during four stages. The first stage corresponds to the plateau-type stage consituted by extensive andesitic and basaltic-andesite lavas and scoria flows that overlie the ignimbritic basement of the volcano. Over these mafic flows, thick dacitic flows were erupted at the northern, southern and southwestern flank of the volcano. After this stage, the main edifice was constructed, presenting two stages: the Old and the Young Cone. The Old Cone Stage was built on the southern part of the volcano. It is constituted by andesitic-to-dacitic lavas and pyroclastic flows. After that, lavic and pyroclastic flows were erupted north of the Old Cone, generating the Young Cone Stage, corresponding to lavas and pyroclastic flows that overlay the previous Old Cone. Composition of the flows of this stage vary from basaltic-andesite to dacite. An 40Ar/39Ar radiometric measure from an basaltic-andesite lava flow of the Young Cone Stage gave a plateau age of 400±50 ka. Significant dissection by glacial erosion affect southern flank of old cone and diverse parts of young cone, being in the last less pervasive. Frontal and lateral morraines deposits are present in the related glacial valleys. The last stage in the evolution of this volcano corresponds to emision of andesitic flows, with autobreccia textures. These flows reach up

  8. Hantaan/Andes virus DNA Vaccine Elicits a Broadly Cross-Reactive Neutralizing Antibody Response in Nonhuman Primates

    DTIC Science & Technology

    2006-01-01

    pulmonary syndrome (HPS). The most prevalent and lethal hantaviruses associated with HFRS and HPS are Hantaan virus (HTNV) and Andes virus (ANDV...Published by Elsevier Inc.Keywords: Hantavirus; DNA vaccine; Hantaan virus; Andes virus; Neutralizing antibodiesIntroduction Hantaviruses are rodent...borne viruses that cause hemor- rhagic fever in humans. Different hantaviruses are associated with different disease syndromes with varying degrees of

  9. 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.

  10. Current state of glaciers in the tropical Andes: a perspective on glacier evolution and climate change

    NASA Astrophysics Data System (ADS)

    Rabatel, Antoine; Francou, Bernard; Soruco, Alvaro; Gomez, Jesus; Caceres, Bolivar; Ceballos, Jorge-Luis; Vuille, Mathias; Sicart, Jean-Emmanuel; Huggel, Christian

    2013-04-01

    This presentation provides a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the LIA (mid 17th - early 18th century). In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, we show that the trend has been quite negative over the past 50 years, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the one computed on a global scale. A break point in the trend appeared in the late 1970s with mean annual mass balance per year decreasing from -0.2 m w.e. in the period 1964-1975 to -0.76 m w.e. in the period 1976-2010. In addition, even if glaciers are currently retreating everywhere in the tropical Andes, it should be noted that this is much more pronounced on small glaciers at low altitudes that do not have a permanent accumulation zone, and which could disappear in the coming years/decades. Monthly mass balance measurements performed in Bolivia, Ecuador and Colombia show that variability of the surface temperature of the Pacific Ocean is the main factor governing variability of the mass balance at the decadal time scale. Precipitation did not display a significant trend in the tropical Andes in the 20th century, and consequently cannot explain the glacier recession. On the other hand, temperature increased at a significant rate of 0.10°C/decade in the last 70 years. The higher frequency of El Niño events and changes in its spatial and temporal occurrence since the late 1970s together with a warming troposphere over the tropical Andes may thus explain much of the recent dramatic shrinkage of glaciers in this part of the world.

  11. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. The SD1 Subdomain of Venezuelan Equine Encephalitis Virus Capsid Protein Plays a Critical Role in Nucleocapsid and Particle Assembly

    PubMed Central

    Reynaud, Josephine M.; Lulla, Valeria; Kim, Dal Young; Frolova, Elena I.

    2015-01-01

    ABSTRACT Venezuelan equine encephalitis virus (VEEV) is an important human and animal pathogen, for which no safe and efficient vaccines or therapeutic means have been developed. Viral particle assembly and budding processes represent potential targets for therapeutic intervention. However, our understanding of the mechanistic process of VEEV assembly, RNA encapsidation, and the roles of different capsid-specific domains in these events remain to be described. The results of this new study demonstrate that the very amino-terminal VEEV capsid-specific subdomain SD1 is a critical player in the particle assembly process. It functions in a virus-specific mode, and its deletion, mutation, or replacement by the same subdomain derived from other alphaviruses has strong negative effects on infectious virus release. VEEV variants with mutated SD1 accumulate adaptive mutations in both SD1 and SD2, which result in a more efficiently replicating phenotype. Moreover, efficient nucleocapsid and particle assembly proceeds only when the two subdomains, SD1 and SD2, are derived from the same alphavirus. These two subdomains together appear to form the central core of VEEV nucleocapsids, and their interaction is one of the driving forces of virion assembly and budding. The similar domain structures of alphavirus capsid proteins suggest that this new knowledge can be applied to other alphaviruses. IMPORTANCE Alphaviruses are a group of human and animal pathogens which cause periodic outbreaks of highly debilitating diseases. Despite significant progress made in understanding the overall structure of alphavirus and VEEV virions, and glycoprotein spikes in particular, the mechanistic process of nucleocapsid assembly, RNA encapsidation, and the roles of different capsid-specific domains in these processes remain to be described. Our new data demonstrate that the very amino-terminal subdomain of Venezuelan equine encephalitis virus capsid protein, SD1, plays a critical role in the

  13. Climate change and water resources in arid mountains: an example from the Bolivian Andes.

    PubMed

    Rangecroft, Sally; Harrison, Stephan; Anderson, Karen; Magrath, John; Castel, Ana Paola; Pacheco, Paula

    2013-11-01

    Climate change is projected to have a strongly negative effect on water supplies in the arid mountains of South America, significantly impacting millions of people. As one of the poorest countries in the region, Bolivia is particularly vulnerable to such changes due to its limited capacity to adapt. Water security is threatened further by glacial recession with Bolivian glaciers losing nearly half their ice mass over the past 50 years raising serious water management concerns. This review examines current trends in water availability and glacier melt in the Bolivian Andes, assesses the driving factors of reduced water availability and identifies key gaps in our knowledge of the Andean cryosphere. The lack of research regarding permafrost water sources in the Bolivian Andes is addressed, with focus on the potential contribution to mountain water supplies provided by rock glaciers.

  14. 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.

  15. Surface uplift in the Central Andes driven by growth of the Altiplano Puna Magma Body.

    PubMed

    Perkins, Jonathan P; Ward, Kevin M; de Silva, Shanaka L; Zandt, George; Beck, Susan L; Finnegan, Noah J

    2016-10-25

    The Altiplano-Puna Magma Body (APMB) in the Central Andes is the largest imaged magma reservoir on Earth, and is located within the second highest orogenic plateau on Earth, the Altiplano-Puna. Although the APMB is a first-order geologic feature similar to the Sierra Nevada batholith, its role in the surface uplift history of the Central Andes remains uncertain. Here we show that a long-wavelength topographic dome overlies the seismically measured extent of the APMB, and gravity data suggest that the uplift is isostatically compensated. Isostatic modelling of the magmatic contribution to dome growth yields melt volumes comparable to those estimated from tomography, and suggests that the APMB growth rate exceeds the peak Cretaceous magmatic flare-up in the Sierran batholith. Our analysis reveals that magmatic addition may provide a contribution to surface uplift on par with lithospheric removal, and illustrates that surface topography may help constrain the magnitude of pluton-scale melt production.

  16. 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.

  17. The ANDES Deep Underground Laboratory in South America: status and prospects

    NASA Astrophysics Data System (ADS)

    Bertou, Xavier

    2017-01-01

    The construction of the Agua Negra tunnel through the Andes between Argentina and Chile is a unique opportunity to build a world class deep underground laboratory in the southern hemisphere, with 1750 m of rock overburden. At 30 degrees latitude south, far from nuclear power plants, it provides a unique site for Dark Matter searches and Neutrino experiments, and can host multidisciplinary experiments with a specific focus on Earth sciences given its location in a peculiar geoactive region. Its operation is foreseen to be coordinated by an international consortium and to start in 2026. In this presentation the current status of the Agua Negra tunnel and the ANDES initiative will be reviewed, and the scientific programme of the planned laboratory will be discussed.

  18. Surface uplift in the Central Andes driven by growth of the Altiplano Puna Magma Body

    NASA Astrophysics Data System (ADS)

    Perkins, Jonathan P.; Ward, Kevin M.; de Silva, Shanaka L.; Zandt, George; Beck, Susan L.; Finnegan, Noah J.

    2016-10-01

    The Altiplano-Puna Magma Body (APMB) in the Central Andes is the largest imaged magma reservoir on Earth, and is located within the second highest orogenic plateau on Earth, the Altiplano-Puna. Although the APMB is a first-order geologic feature similar to the Sierra Nevada batholith, its role in the surface uplift history of the Central Andes remains uncertain. Here we show that a long-wavelength topographic dome overlies the seismically measured extent of the APMB, and gravity data suggest that the uplift is isostatically compensated. Isostatic modelling of the magmatic contribution to dome growth yields melt volumes comparable to those estimated from tomography, and suggests that the APMB growth rate exceeds the peak Cretaceous magmatic flare-up in the Sierran batholith. Our analysis reveals that magmatic addition may provide a contribution to surface uplift on par with lithospheric removal, and illustrates that surface topography may help constrain the magnitude of pluton-scale melt production.

  19. Influence of Cross-Andes Flow on the South American Low-Level Jet.

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Fu, Rong

    2004-03-01

    By analyzing the 15-yr (1979 93) reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF), it has been found that the seasonal and synoptic time-scale variations of the South American low-level jets (LLJs) are largely controlled by an upper-level trough and associated low-level zonal flow, rather than by horizontal temperature gradients along the slope of the Andes. The northerly LLJs are maintained by strong zonal pressure gradients caused by the upstream trough and westerly flow crossing the Andes through lee cyclogenesis. The process involves both baroclinic development of the upper-level trough and mechanical deflection of the westerly flow by the Andes. When an anticyclonic circulation replaces the trough and westerly flow over the eastern South Pacific, the northerly LLJs tend to diminish or reverse into southerly LLJs. The dependence of the LLJs upon the upstream wind pattern helps to explain how the seasonal variation of the South American LLJs is related to the seasonal changes of the large-scale circulation pattern over the eastern South Pacific. On synoptic time scales, the relation between LLJs and cross-Andes zonal flow is strong in austral winter, spring, and fall. This relation weakens somewhat in summer, when Amazon convection is strongest. The analysis also demonstrated strong connections of the LLJs with South American precipitation, intensity of the South Atlantic convergence zone (SACZ), and low-level cross-equatorial flow. A method for up to 5-day forecasts of the LLJs based on 700-hPa zonal winds over the subtropical eastern South Pacific was also introduced. A cross validation indicates a certain degree of predictability for South American LLJs. The results further suggest that the upstream flow pattern over the South Pacific should be closely monitored to determine the variability of the South American LLJs.

  20. Revisiting mountain-building in the Andes of Central Chile: constraints from structural geology and thermochronology.

    NASA Astrophysics Data System (ADS)

    Riesner, M.; Lacassin, R.; Simoes, M.; Armijo, R.; Carrizo, D.

    2015-12-01

    The Andes, one of the most significant reliefs on Earth, is the case example of a subduction-type mountain belt. In central Chile and western Argentina, the particular east-vergent structure of the Aconcagua fold-and-thrust belt (AFTB) is found atop a huge basement high with elevations > 4000 m, the Frontal Cordillera. Classical conceptual models consider the Andes as an east-vergent orogen, opposite to the Nazca subduction, and describe the exhumation of the Frontal Cordillera as an eastward in-sequence event that occurred late in the andean deformation (by ~10My). An alternative model recently challenged this view by proposing that the Andes have mainly a primary westward vergence. Within this scheme, the exhumation of the Frontal Cordillera would have begun earlier, by ~25My, synchronous with formation of the AFTB on the western side of the basement high. Here we test these two models by revisiting structural cross-sections of the Andes at the latitude of Santiago de Chile and of the Aconcagua (~33°S). We provide thermochronological constraints on the timing of exhumation of the Frontal Cordillera by (U-Th)/He dating on apatites retrieved from paleozoic granitoids along a 2,3km high nearly vertical section in the core of the basement high. Preliminary results suggest that the Frontal Cordillera exhumation was not a late event and likely began around 25 Ma. Therefore it appears to be synchronous with deformation within the AFTB and the westernmost fold-and-thrust belt at this latitude. We discuss these results and their implications while building a crustal-scale cross section of the range at the latitude of Santiago de Chile.