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1

The eclipse from Venezuela  

NASA Astrophysics Data System (ADS)

The total solar eclipse of 1998 February 26 was seen in perfect conditions from Peninsula de Paraguana, Venezuela. Measurements were made of solar luminance before, during and after totality. A graph of the light levels is presented.

James, N. D.; Mason, J. W.

1998-06-01

2

Giant fields of Venezuela  

Microsoft Academic Search

Only 44 out of the nearly 300 oil fields discovered in Venezuela to the end of 1965 could be classified as giants, i.e., fields having resource of at least 100 million bbl of oil. Giant fields have been discovered in three of the sedimentary basins of the country. The average time lag for the recognition of an oil field as

1968-01-01

3

Astronomy in Venezuela  

NASA Astrophysics Data System (ADS)

Since the installation of the Observatorio Cagigal in Caracas, astronomy in Venezuela has developed steadily, and, in the last few decades, has been strong. Both theoretical and observational astronomy now flourish in Venezuela. A research group, Grupo de Astrofísica (GA) at the Universidad de Los Andes (ULA) in Mérida, started with few members but now has increased its numbers and undergone many transformations, promoting the creation of the Grupo de Astrofísica Teórica (CAT), and with other collaborators initiated the creation of a graduate study program (that offers master's and doctor's degrees) in the Postgrado de Física Fundamental of ULA. With the financial support of domestic Science Foundations such as CONICIT, CDCHT, Fundacite, and individual and collective grants, many research projects have been started and many others are planned. Venezuelan astronomy has benefitted from the interest of researchers in other countries, who have helped to improve our scientific output and instrumentation. With the important collaboration of national and foreign institutions, astronomy is becoming one of the strongest disciplines of the next decade in Venezuela.

Rosenzweig, Patricia

4

ALBA: A Political Tool for Venezuela’s Foreign Policy  

Microsoft Academic Search

Despite its founding by Hugo Chávez on the heels of the failed Free Trade Area for the Americas (FTAA) negotiations which took place November 2003, the Bolivarian Alliance for the Americas (ALBA, as it is known for its Spanish acronym) has evolved into a political tool that uses “social power” to facilitate Venezuela?s positioning as the leader of the anti-U.S.

Erich de la Fuente

2011-01-01

5

The challenge of Venezuela: a SWOT analysis  

Microsoft Academic Search

Venezuela ranks fifth in the world in oil proven reserves and has the largest accumulation of liquid fuel in the world. With its importance as an oil country, many countries including the U.S. have expressed concerns about Venezuela’s current economic and political situation. Using the popular SWOT analysis, Strengths, Weaknesses, Opportunities and Threats facing the country, are identified. The discussion

Carolina Duarte; Lawrence P. Ettkin; Marilyn M. Helms; Michael S. Anderson

2006-01-01

6

Excerpts from Student Papers on Venezuela  

Microsoft Academic Search

in Venezuela. By 1929, Venezuela was the world's second largest oil producer, after the U.S., and the world's largest oil exporter. In 1943, the Hydrocarbons Act reformed Venezuela's oil policy, closely tying oil profits to the state's income. Previously oil income was based on concessions, but the Hydrocarbons Act connected oil revenues to taxes on the mining companies. Foreign companies

Alexis Henry

7

Media and Consumerism in Venezuela.  

ERIC Educational Resources Information Center

|Outlines opposing theories of the role of the commercial mass media in national economic development; reports on a survey of the attitudes of 636 adult residents of Barquisimeto, Venezuela, with respect to consumption, advertising, and national development, and shows how the results relate to the theory proposed by Daniel Lerner. (GT)|

Martin, Richard; And Others

1979-01-01

8

78 FR 58556 - Silicomanganese From India, Kazakhstan, and Venezuela  

Federal Register 2010, 2011, 2012, 2013

...Review)] Silicomanganese From India, Kazakhstan, and Venezuela Determination On the...imports of silicomanganese from India, Kazakhstan, and Venezuela would be likely to lead...entitled Silicomanganese from India, Kazakhstan, and Venezuela: Investigation...

2013-09-24

9

Energy policies of the world: Venezuela  

Microsoft Academic Search

Venezuela ranks fifth in the world in total oil output and 92 percent of its production in 1974 was exported, making it the third largest exporter after Saudi Arabia and Iran. No comprehensive energy policy has been reached yet, but important separate decisions by the government indicate policy directions. The use of energy in Venezuela has been conditioned by the

1975-01-01

10

Hyperreactive malarial splenomegaly in Venezuela.  

PubMed

A cross-sectional seroepidemiological survey seeking hyperreactive malarial splenomegaly was carried out in isolated Yanomami hamlets in Amazonas Territory in Venezuela. All 110 inhabitants greater than 1 year of age were evaluated clinically and 98 were studied immunologically. The spleen index for individuals greater than 10 years of age was 44%. Only 3 patients had Plasmodium spp. on thick blood smears. All had serological evidence of infection with Plasmodium falciparum and P. vivax. Twenty-three patients were considered to show hyperreactive malarial splenomegaly. Clinical manifestations of the syndrome did not differ from those described in other parts of the world. PMID:3041852

Torres, J; Noya, O; Mondolfi, A; Peceño, C; Botto, C

1988-07-01

11

Republic of Venezuela. Country profile.  

PubMed

Venezuela's current economic and demographic situation is described. Venezuela is a major oil country, and the oil industry accounts for 90% of the country's foreign exchange, 70% of the government's revenues, and 15% of the gross domestic product. The economy experienced a sudden and high rate of economic growth in the mid-1970s as a result of high oil prices; however, in recent years, declining oil prices have had a negative effect on the economy. The country is now faced with a serious trade deficit, and the government recently imposed restrictions on imports. Imports in recently years had increased markedly. The emphasis on the oil industry weakened the agricultural sector and, as a result, food imports increased. In addition, the rapid economic growth experienced during the 1970s greatly increased the demand for imported consumer goods. Venezuela has the 4th highest foreign debt in the world (US$35 billion). Despite these problems Venezuela has a relatively high per capita income (US$4,140) and living standard, compared to other countries in the region. Venezuela's total population is 14.6 million, and the population is unevenly distributed. 86% of the population lives in cities of 2500 or more. 37.4% of the population and 70% of the industry is concentrated in the Federal District which contains Caracas, and in the surrounding states of Aragua, Miranda, and Carabobo. This area constitutes only 2.36% of the country's territory. Most of the oil fields are located in the state of Zulia which also contains the country's 2nd largest city (Maracaibo). The country's coastal area contains most of the agricultural lands, and the prairies just south of the coastal mountain ranges are devoted primarily to cattle raising. The remaining 58.2% of the country's territory is essentially jungle and contains only 6.9% of the country's population. The annual population growth rate is 3.11%. Although the rate declined in recent years it is higher than in most of the other countries in the region. In 1981, 1 million of the countrys, residents were foreign born. The oil industry attracted many immigrants, and illegal immigration is a serious problem. 41% of the population is under 15 years of age, the birth rate is 33-37, the death rate is 5, the infant mortality rate is 39, and life expectancy is 69 years. Average household size is 5.28. Family life is highly unstable. 32% of the couples are in informal unions, and these couples account for 52% of all births. 20% of the households are headed by low income women. The total fertility rate was 6.7 in 1961 and is currently 4.3. There are 3.2 million housing units, and 800,000 of these are classified as inadequate. 65% of the population is mestizo, 20% is European, and the remaining 15% are from various other countries or members of indigenous groups. The population is predominantly Catholic. The literacy rate is 83%; however, 71% of the males and 84% of the females in rural areas are illiterate. 31.5% of the population is in the labor force, and 27.5% of the labor force is female. 20% of the labor force is in the service sector and many of these work in the overgrown government bureaucracy. Only 15% of the labor force is engaged in the primary sector. 37% of the residents of Caracas and 80% of the country's rural residents live below the poverty level. PMID:12313690

Hakkert, R

1985-06-01

12

Ceuta-Tomoporo field, Venezuela  

SciTech Connect

Ceuta field is located in the southeastern part of the Maracaibo basin, western Venezuela. The field is a conspicuous high belonging to the Pueblo Viejo trend, a set of strike-slip faults trending northwest. The field has an area of 320 km and is divided into eight fault-bounded blocks where light- or medium-grade oil is being produced. The structural framework is characterized by a major left-slip fault and oil accumulations are associated with compressive and extensive structural features. The deposition of Eocene sediments in some areas may have been controlled by normal faulting and a period of shortening may have altered the character of some of the faults during the late Eocene or later. The main producing intervals are shallow-water marine or fluviodeltaic Miocene and Eocene sands with porosities ranging from 8 to 15% and a production potential of up to 3,500 BOPD from depths averaging 5,182 m (17,000 ft). The reservoirs seem to contain mixtures of hydrocarbons, probably due to the generation of oil in more than one oil kitchen and/or at different migration times from a common drainage area.

Puig, E.R.; Fernando Marcano, R. (Maraven S.A., Caracas (Venezuela))

1990-09-01

13

Impacto humano sobre los carnívoros de Venezuela  

Microsoft Academic Search

Twenty one species of Neotropical carnivores are found in Venezuela. Ten are considered in a critical situation and the Venezuelan government limits the capture of sex species by a present low population level. Up to now the distribution and habitat association of carnivores may have no positive or negative effect on human activities. Among candids the bush dog (Speothos venalicus)

Francisco J. Bisbal

1993-01-01

14

Country Analysis Briefs: Venezuela, January 2009.  

National Technical Information Service (NTIS)

Venezuela is one of the worlds largest exporters of crude oil and the largest in the Western Hemisphere. In 2007, the country was the seventh-largest net oil exporter in the world. The oil sector is of central importance to the Venezuelan economy: it acco...

2009-01-01

15

Mastery: A Lesson from Maria in Venezuela  

ERIC Educational Resources Information Center

|Children who have been born into poverty or into at-risk circumstances are often considered "disposable" and not a societal priority. These youngsters have few advocates and limited successful options in life. In the city of Maracaibo, Venezuela, there is a large population of Amerindians who are called Guajiros. These indigenous people have…

Powell, Sandra Anez; Powell, Norman W.

2012-01-01

16

Globalization and Health: Venezuela and Cuba  

Microsoft Academic Search

This article explores the impact of globalization and neo-liberal reforms on the health of Venezuelans and Cubans during the 1980s and 1990s. It seeks to illustrate, through the lens of health care, how global economic forces affect national development and people's lives. Venezuela and Cuba struggled with severe economic crises and their health systems suffered. Cuba, however, was able to

George W. Schuyler

2002-01-01

17

Gravity Field and Plate Boundaries in Venezuela.  

National Technical Information Service (NTIS)

Free-air and simple Bouger anomaly maps of the Venezuelan continental margin are presented. The major features of the free-air map are: the large lows associated with the deep sedimentary basins, -200 mgal in the eastern Venezuela basin and -164 mgal in t...

R. A. Folinsbee

1972-01-01

18

Perspectives of CO2 Injection in Venezuela  

Microsoft Academic Search

Venezuela's condensed and light and medium crude oil fields have been under exploitation for more than four decades using water and gas injection. To date, the expected recovery factors are about 30% and 45% of the OOIP for water and gas injection projects, respectively. Given the maturity of these resources, IOR projects will be required, but they have to be

E. Manrique; A. Ranson; V. Alvarado

19

e-Science initiatives in Venezuela  

Microsoft Academic Search

Within the context of the nascent e-Science in- frastructure in Venezuela, we describe several web- based scientific applications developed at the Cen- tro Nacional de C´ alculo Cient´ifico Universidad de Los Andes (CECALCULA), Merida, and at the Instituto Venezolano de Investigaciones Cient´ificas (IVIC), Caracas. The different strategies that have been followed for implementing quantum chemistry and atomic physics applications are

J. L. Chaves; G. Diaz; V. Hamar; R. Isea; F. Rojas; N. Ruiz; Rodrigo Torrens; Maylett Uzcategui; Julio Flórez-lópez; H. Hoeger; C. Mendoza; Luis A. Núñez

2007-01-01

20

Thermal modeling in Ceuta, Maracaibo Basin, Venezuela  

Microsoft Academic Search

Hydrocarbon generation from Upper Cretaceous source rocks (Fm.La Luna) in Ceuta, center-eastern Maracaibo lake area in Venezuela, is modeled here, using a kinetic method and the conventional Time-Temperature Index (TTI) procedure. Geological evolution, burial and erosional history is based on available interpretation of 3D seismic and well data. Fragmentary present-day subsurface temperature data comes from corrected measurements in a few

F. Marcano; S. Padron

1993-01-01

21

The new emergency structure of the Istituto Nazionale di Geofisica e Vulcanologia during the L’Aquila 2009 seismic sequence: the contribution of the COES (Seismological Emergency Operation Center - Centro Operativo Emergenza Sismica)  

NASA Astrophysics Data System (ADS)

The Centro Nazionale Terremoti (CNT - National Earthquake Center), departement of Istituto Nazionale di Geofisica e Vulcanologia (INGV), has designed and setup a rapid response emergency structure to face the occurrence of strong earthquakes. This structure is composed by a real time satellite telemetered temporary seismic network (see Abruzzese et al., 2009 Fall AGU) used to improve the hypocentral locations of the INGV National Seismic Network, a stand alone temporary seismic network whose goal is primarily the high dynamic/high resolution data acquisition in the epicentral area and a mobile operational center, the COES (Centro Operativo Emergenza Sismica, Seismological Emergency Operational Center). The COES structure is a sort of mobile office equipped with satellite internet communication that can be rapidly installed in the disaster area to support all the INGV staff operative needs and to cooperate with the Civil Protection department (DPC) aggregating all the scientific information available on the seismic sequence and providing updated information to Civil Protection for the decision making stage during the emergency. The structure is equipped with a heavy load trolley that carries a 6x6 inflatable tent, a satellite router, an UPS, computers, monitors and furniture. The facility can be installed in a couple of hours in the epicentral area and provides a full featured office with dedicated internet connection and VPN access to the INGV data management center in Rome. Just after the April 6 2009 Mw 6.3 earthquake in L’Aquila (Central Italy) the COES has been installed upon request of the Italian Civil Protection (DPC) in the DICOMAC (Directorate of Command and Control - which is the central structure of the DPC that coordinates the emergency activities in the areas affected by the earthquake) located in the Guardia di Finanza headquarters in Coppito nearby L'Aquila (the same location that hosted the G8 meeting). The COES produces real time reports on the seismic sequence evolution constituted by a detailed sequence map, histograms showing the evolution of the magnitude and the number of earthquakes in time and a daily event list. Moreover, it is possible to see the real time hypocentral locations using “SISMAP” (Doumaz et al., 2008), the same tool used in the Seismic Monitoring Center in Rome. During the emergency the COES has been also a reference information point for all people involved in the crisis management and has provided also psychological support to the rescuers and to the earthquake affected population. This education and outreach activity has proved to be extremely effective. References Abruzzese L. et al., AGU Fall Meeting 2009. Doumaz F. et al., Geomedia, speciale geologia, pp. 10-13, 2008.

Moretti, M.; Govoni, A.; Nostro, C.; La Longa, F.; Crescimbene, M.; Pignone, M.; Selvaggi, G.; Working Group, C.

2009-12-01

22

The Dairy Technology System in Venezuela. Summary of Research 79.  

ERIC Educational Resources Information Center

A study examined the agricultural technology system in Venezuela with emphasis on the dairy industry. An analytical framework was used to identify the strengths and weaknesses of the following components of Venezuela's agricultural technology system: policy, technology development, technology transfer, and technology use. Selected government…

Nieto, Ruben D.; Henderson, Janet L.

23

The Dairy Technology System in Venezuela. Summary of Research 79.  

ERIC Educational Resources Information Center

|A study examined the agricultural technology system in Venezuela with emphasis on the dairy industry. An analytical framework was used to identify the strengths and weaknesses of the following components of Venezuela's agricultural technology system: policy, technology development, technology transfer, and technology use. Selected government…

Nieto, Ruben D.; Henderson, Janet L.

24

Venezuela Country Set (1992). Foreign Economic Trends Report (December 1991).  

National Technical Information Service (NTIS)

The report outlines the current economic situation and trends for Venezuela. It begins with a table of key economic indicators for the years 1989-1991. For U.S. exporters, Venezuela is a significant market. It ranks behind Mexico as the second largest in ...

1992-01-01

25

PRIMER REGISTRO DE LA FAMILIA PELAGORNITHIDAE (AVES: PELECANIFORMES) PARA VENEZUELA  

Microsoft Academic Search

First record of Pelagornithidae family from Venezuela. Pelagornithidae (Aves: Pelecaniformes) family is registered from Ve- nezuela. The specimen comes from Cave of Zumbador, which is developed in Middle Miocene limestone of the Capadare Formation exposed in Ce- rro Misión eastern Falcón state, Venezuela. The discovery of this specimen represents the first record of a vertebrate fossil for Capadare Formation and

Ascanio D. RINCÓN; Marcelo STUCCHI

26

Venezuela after a century of oil exploitation Chapter for the book Venezuela: Anatomy of a Collapse  

Microsoft Academic Search

This chapter reviews the Venezuelan oil sector's performance and compares it with the performance of the oil sector of similar oil producing countries. Oil fiscal revenue per capita evolution in the last 30 years has resembled that of the Venezuela GDP per capita. After three decades of sustained growth, it collapsed in the eighties and it has not recovered since.

Osmel Manzano

27

Venezuela after a century of oil exploitation  

Microsoft Academic Search

Abstract This chapter,reviews,the Venezuelan,oil sector’s performance,and compares,it with the performance,of the oil sector,of similar,oil producing,countries. Oil fiscal revenue,per capita evolution,in the last 30 years has resembled,that of the Venezuela,GDP per capita. After three decades of sustained growth, it collapsed in the eighties and it has not recovered,since. The chapter,will argue that the main,reason,for this performance,of the oil sector was unchanged,policy

Osmel Manzano

28

El Fenomeno Chavez: Hugo Chavez of Venezuela, Modern Day Bolivar.  

National Technical Information Service (NTIS)

Hugo Chavez, the charismatic and controversial President of Venezuela, reached the ultimate seat of political power with his election as head of state in 1998. Carefully cultivating the image of an impoverished Venezuelan youth reaching the highest politi...

J. M. Post

2007-01-01

29

Western Venezuela Power Generation Expansion Study. Final Report.  

National Technical Information Service (NTIS)

Power Tech Associates conducted this study in 2003 to determine the feasibility of creating additional power generating capacity at ENELVEN's Ramon Laguna facility in Maracaibo, Venezuela. As part of the investigation existing units are assessed and alter...

2003-01-01

30

Petroleum resources of Venezuela and Trinidad and Tobago  

SciTech Connect

The status of known and ultimately recoverable crude oil and natural gas resources of the Federal Republics of Venezuela, and Trinidad and Tobago (hereafter referred to as Trinidad) is set forth in this report. The rates that oil resources may be available to world markets are also covered in the report. A section on the petroleum geology of the region is included. The Republics of Venezuela and Trinidad share a common and ancient petroleum history. Over a century of exploration and development have resulted in the cumulative production of nearly 39 billion barrels of oil from Venezuela and over 2 billion barrels from Trinidad. Both republics have passed their peak status as oil producers. Venezuela reached its peak as the second largest producer in the world in the mid-fifties, and Trinidad attained its highest status as the eighth largest oil producer in the early forties. The report concludes that Venezuela and Trinidad have depleted slightly less than one-half of their ultimately recoverable crude oil resources. Based on feasible production rates and estimates of remaining recoverable resources, nearly two-thirds of Venezuela's oil resources and about three-fourths of Trinidad's oil resources may be depleted by the year 2000. The natural gas resources of both countries are underutilized and underdeveloped.

Not Available

1983-07-01

31

Digital shaded-relief map of Venezuela  

USGS Publications Warehouse

The Digital Shaded-Relief Map of Venezuela is a composite of more than 20 tiles of 90 meter (3 arc second) pixel resolution elevation data, captured during the Shuttle Radar Topography Mission (SRTM) in February 2000. The SRTM, a joint project between the National Geospatial-Intelligence Agency (NGA) and the National Aeronautics and Space Administration (NASA), provides the most accurate and comprehensive international digital elevation dataset ever assembled. The 10-day flight mission aboard the U.S. Space Shuttle Endeavour obtained elevation data for about 80% of the world's landmass at 3-5 meter pixel resolution through the use of synthetic aperture radar (SAR) technology. SAR is desirable because it acquires data along continuous swaths, maintaining data consistency across large areas, independent of cloud cover. Swaths were captured at an altitude of 230 km, and are approximately 225 km wide with varying lengths. Rendering of the shaded-relief image required editing of the raw elevation data to remove numerous holes and anomalously high and low values inherent in the dataset. Customized ArcInfo Arc Macro Language (AML) scripts were written to interpolate areas of null values and generalize irregular elevation spikes and wells. Coastlines and major water bodies used as a clipping mask were extracted from 1:500,000-scale geologic maps of Venezuela (Bellizzia and others, 1976). The shaded-relief image was rendered with an illumination azimuth of 315? and an altitude of 65?. A vertical exaggeration of 2X was applied to the image to enhance land-surface features. Image post-processing techniques were accomplished using conventional desktop imaging software.

Garrity, Christopher P.; Hackley, Paul C.; Urbani, Franco

2004-01-01

32

Tertiary evolution of the northeastern Venezuela offshore  

NASA Astrophysics Data System (ADS)

On the northeastern offshore Venezuela, the pre-Tertiary basement consists of a deeply subducted accretionary complex of a Cretaceous island arc system that formed far to the west of its present location. The internal structure of this basement consists of metamorphic nappes that involve passive margin sequences, as well as oceanic (ophiolitic) elements. The Tertiary evolution of the northeastern Venezuela offshore is dominated by Paleogene (Middle Eocene-Oligocene) extension and Neogene transtension, interrupted by Oligocene to Middle Miocene inversions. The Paleogene extension is mainly an arc-normal extension associated with a retreating subduction boundary. It is limited to the La Tortuga and the La Blanquilla Basins and the southeastern Margarita and Caracolito subbasins. All of these basins are farther north of and not directly tied to the El Pilar fault system. On a reconstruction, these Paleogene extensional systems were located to the north of the present day Maracaibo Basin. By early Miocene the leading edge of the now overall transpressional system had migrated to a position to the north of the Ensenada de Barcelona. This relative to South America eastward migration is responsible for the Margarita strike-slip fault and the major inversions that began during the Oligocene and lasted into the Middle Miocene. The Bocono-El Pilar-Casanay-Warm Springs and the La Tortuga-Coche-North Coast fault systems are exclusively Neogene with major transtension occurring during the Late Miocene to Recent and act independently from the earlier Paleogene extensional system. They are responsible for the large Neogene transtensional basins of the area: the Cariaco trough, the Northern Tuy-Cariaco and the Paria sub-basins, and the Gulf of Paria Basin. This latest phase is characterized by strain-partitioning into strike slip faults, a transtensional northern domain and a transpressional southern domain that is responsible for the decollement tectonics and/or inversions of the Serrania del Interior and its associated Monagas foreland structures. Part of the latest (Middle Miocene to Recent) phase is the formation of a large arch that corresponds to the Margarita-Testigos-Grenada zone which perhaps was subject to mild lithospheric compression during the Plio-Pleistocene.

Ysaccis B., Raul

1998-12-01

33

Digital geologic map and GIS database of Venezuela  

USGS Publications Warehouse

The digital geologic map and GIS database of Venezuela captures GIS compatible geologic and hydrologic data from the 'Geologic Shaded Relief Map of Venezuela,' which was released online as U.S. Geological Survey Open-File Report 2005-1038. Digital datasets and corresponding metadata files are stored in ESRI geodatabase format; accessible via ArcGIS 9.X. Feature classes in the geodatabase include geologic unit polygons, open water polygons, coincident geologic unit linework (contacts, faults, etc.) and non-coincident geologic unit linework (folds, drainage networks, etc.). Geologic unit polygon data were attributed for age, name, and lithologic type following the Lexico Estratigrafico de Venezuela. All digital datasets were captured from source data at 1:750,000. Although users may view and analyze data at varying scales, the authors make no guarantee as to the accuracy of the data at scales larger than 1:750,000.

Garrity, Christopher P.; Hackley, Paul C.; Urbani, Franco

2006-01-01

34

A new species of Corydalus Latreille from Venezuela (Megaloptera, Corydalidae)  

PubMed Central

Abstract A new species of dobsonfly, Corydalus wanningeri, from Venezuela, is described and illustrated. It superficially resembles Corydalus neblinensis Contreras-Ramos, with a uniform reddish coloration of body and wings. Yet, because of male genitalic structure it might be closely related to Corydalus crossi Contreras-Ramos. Specimens were collected from a rain forest transitional zone between the Orinoco lowlands and the Gran Sabana plateau, in Bolívar state. This is the 15th species of Corydalus to be recorded from Venezuela, rendering this the country with the highest number of documented Corydalus species. A key to the sexually dimorphic, long-mandibled Venezuelan species of the genus is provided.

Contreras-Ramos, Atilano; von der Dunk, Klaus

2010-01-01

35

The National Seismological Network of Venezuela, Future Aims and Goals  

Microsoft Academic Search

The Venezuelan coastline mainly coincides with the plate tectonic boundary between the Caribbean and South American plate. The relative movement is accomodated in numerous west - east trending sub-parallel faults. The Venezuelan Andes are dominated by the broad southwest-northeast trending Bocono fault system. This plate tectonic setting causes a wide range of seismic activity in Venezuela. Among the various phenomenons

N. Orihuela; H. Rendon; G. Romero; R. Lopez; M. Sobiesiak; L. Ottemoeller; G. Tovar

2001-01-01

36

Experimental life cycle of Philophthalmus gralli (Trematoda: Philophthalmidae) in Venezuela  

Microsoft Academic Search

Descriptions of the miracidium, mother redia, daughter redia, grandaughter redia, cercaria, metacer- caria and adult stages of Philophthalmus gralli Mathis and Leger,1910 recovered from experimental infections are presented. The intermediate host, Melanoides tuberculata, was collected from freshwater rivulets in Aguasanta and Yaguracual, Sucre State, Venezuela. Chicken were orally infected with cercariae and metacer- cariae, and metacercariae were introduced directly into

Marcos T. Díaz; Luz E. Hernández; Abul K. Bashirullah

37

Late Pleistocene carbonate dissolution in the Venezuela Basin, Caribbean Sea  

SciTech Connect

Piston cores from water depths greater than 4000 m in the Venezuela Basin (Caribbean Sea) provide continuous late Pleistocene records of carbonate dissolution and accumulation. The authors examination of multiple dissolution indices indicate that, at least for the last 150,000 years, dissolution of carbonate in the Venezuela Basin has been more intense during interglacial than glacial periods, a pattern opposite to more general observations from the deep Atlantic and Gulf of Mexico. By virtue of its shallow sill depth (1815 m), the Venezuela Basin is relatively isolated from the mainstream of Atlantic thermohaline circulation, and presently is filled with homogeneous, relatively warm (3.8/sup 0/C) waters primarily derived from Upper North Atlantic Deep Water. During the last glacial, the enhanced preservation of carbonate in the Venezuela Basin suggests the presence of a less corrosive, more oxygenated water mass in the Atlantic near sill depth. However, this simple interpretations is potentially complicated by past changes in the rain of biogenic materials from surface waters to the deep basin in what must be an essentially closed system below sill depth. Their observations of increased interglacial dissolution may help to explain previously noted discrepancies in the local glacial to interglacial amplitude of delta/sup 18/O variations recorded by coccoliths and planktonic foraminifera.

Cofer-Shabica, N.B.; Peterson, L.C.

1985-01-01

38

Molecular epidemiologic source tracking of orally transmitted Chagas disease, Venezuela.  

PubMed

Oral outbreaks of Chagas disease are increasingly reported in Latin America. The transitory presence of Trypanosoma cruzi parasites within contaminated foods, and the rapid consumption of those foods, precludes precise identification of outbreak origin. We report source attribution for 2 peri-urban oral outbreaks of Chagas disease in Venezuela via high resolution microsatellite typing. PMID:23768982

Segovia, Maikell; Carrasco, Hernán J; Martínez, Clara E; Messenger, Louisa A; Nessi, Anaibeth; Londoño, Juan C; Espinosa, Raul; Martínez, Cinda; Alfredo, Mijares; Bonfante-Cabarcas, Rafael; Lewis, Michael D; de Noya, Belkisyolé A; Miles, Michael A; Llewellyn, Martin S

2013-07-01

39

UN CASO CLÍNICO DE MIONEUROPATÍA ALCOHÓLICA EN MÉRIDA, VENEZUELA  

Microsoft Academic Search

A clinical case of alcoholic myoneuropathy in Mérida, Venezuela. Alcohol may induce lesions at scheletical striated muscles producing toxic miopathies due to the indiscriminate and long time consumption of this social drug. A clinical case is presented: A male patient, 48 years age, chronic alcoholic (20 years evolution), admitted by the Internal Medicine Service, presenting the syndrome of alcoholic abstinence.

Manuel Méndez García; Elisnel Cáceres; Antonio Pérez Colmenares; Pedro José Salinas

40

Assessing Whether Oil Dependency in Venezuela Contributes to National Instability  

Microsoft Academic Search

The focus of this article is on what role, if any, oil has on Venezuela's instability. When trying to explain why a resource-rich country experiences slow or negative growth, experts often point to the resource curse. The following pages explore the traditional theory behind the resource curse as well as alternative perspectives to this theory such as ownership structure and

Adam Kott

2012-01-01

41

Aqua regia extractable trace elements in surface soils of venezuela  

Microsoft Academic Search

Surface soils (0–15 cm) were sampled at 10–20 km intervals along two transects in Venezuela. One (1162 km, 70 samples) ran west to east parallel with the Caribbean coastline, the other (920 km, 92 samples) ran south to north from the frontier with Brazil to the Caribbean shore. Sampling took place in both a wet and a dry season. Trace

B. E. Davies; Claudio Bifano; K. M. Phillips; J. L. Mogollon; M. Torres

1999-01-01

42

[Epidemiology of ophidism in Venezuela (1996-2004)].  

PubMed

The data of accidents caused by snakebites in Venezuela, registered at the morbidity statistics of the Direction of Epidemiology and Strategic Analysis of the Ministry of Health and Social Development were analyzed. During the years of 1996-2004, 53,792 snakebites were registered in Venezuela (5,976 cases average per year), with a higher incidence during the year 2004 (7,486 incidents). Zulia reported the highest frequency of all the states (5,975 cases); meanwhile the Midwestern region, constituted by Lara, Portuguesa, Falc6n and Yaracuy states, had a higher morbidity for snake bites. The highest incidence, distributed per states was registered in Cojedes, during the year 2001, with 228.72 cases per 100,000 inhabitants. When it was determined by regions, the highest incidence occurred during the year 2004 at los Llanos with 63.81 per 100,000 inhabitants. The median of the incidence rate for Venezuela during the period was of 21.46 accidents per 100,000 inhabitants. The classification of the endemic areas for ophidism, according to the percentiles 23, 50, 75 and 90, organized the country in: (a) states and regions of very high endemicity, (b) high endemicity, (c) middle, (d) low and (e) very low endemicity. These epidemiological data indicated that the accidents caused by snakes constitute a collective health problem in Venezuela. PMID:23947002

De Sousa, Leonardo; Bastouri-Carrasco, Jessica; Matos, Mercedes; Borges, Adolfo; Bónoli, Stefano; Vásquez-Suárez, Aleikar; Guerrero, Belsy; Rodríguez-Acosta, Alexis

2013-06-01

43

Magnetic fabric of peridotite with intersecting petrofabric surfaces, Tinaquillo, Venezuela  

Microsoft Academic Search

Two intersecting structural surfaces of different ages and origins are characteristic of the Tinaquillo (Venezuela) peridotite. An older penetrative mylonitic foliation is cut by younger serpentine veinlets. The anisotropy of magnetic susceptibility (AMS) is influenced by both petrofabric components. The dominant fabric surface from the AMS perspective is defined by serpentine veinlets, probably because of the abundant secondary magnetite associated

W. D. MacDonald; Brooks B. Ellwood

1988-01-01

44

Poverty rates in Venezuela: getting the numbers right.  

PubMed

This article looks at household and individual poverty rates in Venezuela over the past seven years. For more than a year, the statement that poverty in Venezuela has increased under the government of President Hugo Chávez has appeared in scores of major newspapers, on major television and radio programs, and even in publications devoted to foreign policy. There are no data to support such statements, and in fact the available data show a decline in poverty for both individuals and households over the seven-year period: the percentage of people in poverty declined from 50 percent in the first quarter of 1999 to 43.7 percent in 2005. Further, there is no evidence to suggest any change in the methodology for measuring poverty during this period, as has been alleged in a number of reports. The article also examines briefly the impact of significant changes in non-cash benefits such as free health care, which are not taken into account in the measured poverty rate, on poor people in Venezuela. Finally, the authors look at how the mistakes in reporting on Venezuela's poverty rate were made; an appendix gives examples of mistakes in major media and foreign policy publications. PMID:17175848

Weisbrot, Mark; Sandoval, Luis; Rosnick, David

2006-01-01

45

Medical Genetics in Zulia, a State of Venezuela  

Microsoft Academic Search

Zulia is a state located in the northwest of Venezuela. Congenital malformations, deformities and chromosomal anomalies are the second cause of infant and neonatal mortality. There are seven public and private groups providing genetic services, the most important of which, the Medical Genetic Unit at the Zulia University was created in 1973. So far, this unit has provided genetic services

Sandra González-Ferrer; Lennie Pineda-Bernal; Wilmer Delgado-Luengo; Heber Villalobos-Cabrera

2004-01-01

46

The Market for Building Products and Construction Equipment in Venezuela.  

National Technical Information Service (NTIS)

The market research was undertaken to study the present and potential US share of the market in Venezuela for building products and construction equipment; to examine growth trends in Venezuelan end-user industries over the next few years; to identify spe...

1976-01-01

47

Oil and development in Venezuela during the Twentieth Century  

Microsoft Academic Search

This book provides a useful contribution to data on national income accounts and balance-of-payments statistics of Venezuela from 1910 to 1990. The author provides a brief introduction to theories of the relation between the growth of exports and economic development. He believes that positive effects of export growth include increased efficiency in the rest of the economy, increased national income

J. Salazar-Carrillo; R. D. Cruz

1994-01-01

48

Epidemiological aspects of human and canine visceral leishmaniasis in Venezuela  

Microsoft Academic Search

Objective. To report recent data on the distribution of human and canine visceral leishma- niasis (VL) in Venezuela, and to highlight problems associated with effective control measures. Methods. We report the number of cases, incidence rate, age and sex distribution, and mor- tality rates for human VL (HVL) for the period of 1995 through 2000, based on National Reg- istry

Olga Zerpa; Marian Ulrich; Rafael Borges; Vestalia Rodríguez; Marta Centeno; Emilia Negrón; Doris Belizario; Jacinto Convit

2003-01-01

49

Geology and geochemistry of crude oils, Bolivar Coastal Fields, Venezuela  

Microsoft Academic Search

The Bolivar Coastal Fields (BCF) are located on the eastern margin of Lake Maracaibo, Venezuela. They form the largest oil field outside of the Middle East and contain oil which is mostly heavy with a gravity less than 22° API. Lake Maracaibo is now in an intermontane basin enclosed on three sides by the Andes Mountains. The area has a

M. Bockmeulen; C. Barker; P. A. Dickey

1983-01-01

50

Geology and geochemistry of crude oils, Bolivar coastal fields, Venezuela  

Microsoft Academic Search

The Bolivar Coastal Fields (BCF) are located on the eastern margin of Lake Maracaibo, Venezuela. They form the largest oil field outside of the Middle East and contain mostly heavy oil with a gravity less than 22° API. Thirty crude oils from the BCF were collected along two parallel and generally southwest-northeast trends. These oils were characterized by their API

H. Bockmeulen; C. Barker; P. A. Dickey

1983-01-01

51

Paleoseismology in Venezuela: Objectives, methods, applications, limitations and perspectives  

NASA Astrophysics Data System (ADS)

The privileged location of Venezuela along an active interplate deformation belt, despite of being a “so-called” developing country, has led to a long paleoseismic tradition as attested by 45 trench assessments since 1968. Since then, a first 2-trench study was carried out by the American Woodward Clyde company across the Oca fault at Sinamaica. Since 1980, all further paleoseismic studies have been performed by FUNVISIS and the Uribante Caparo hydroelectric project (southern Mérida Andes) became their first assessment where 22 huge trenches were bulldozer-dug. Except for these Compañía Anónima de Administración y Fomento Eléctrico (CADAFE) financed trenches and two others, all other assessments were for Petróleos de Venezuela S. A. —PDVSA . In this paper, geographic and geologic factors, as well as logistic limitations, conditioning success in paleoseismic studies by trenching, shall be discussed based on the Venezuelan experience developed over the years. The scientific contribution of this approach refer to: confirmation of Holocene fault activity, slip-per-event and average slip rate of a given fault (or segment), seismic potential (repeat of maximum credible earthquakes) of known faults, fault segmentation, fault interaction as consequence of stress loading by stick-slip on contiguous faults, time-space distribution of seismic activity along a given tectonic feature, seismotectonic association of historical earthquakes and landscape evolution on the short term and its implications on the long-term evolution (poorly discussed since this is really part of the field of Neotectonics). In recent years (since 1999), a new approach has been introduced in Venezuela consisting in complementing the seismic history derived from trenching studies with the evaluation of seismically induced perturbations in the continuous Quaternary sedimentary record of (either active or fossil) lakes. The future of this discipline in Venezuela heads to more trenching and lake coring in order to gather more data on the previously mentioned aspects. Other paleoseismic approaches have been developed very little in Venezuela since either climate or the geodynamic setting do not favor their application.

Audemard M., Franck A.

2005-10-01

52

La dinámica político-territorial de Venezuela, los planes de ordenamiento y el ingreso petrolero Territorial planning, oil income and the political territorial dinamics in Venezuela  

Microsoft Academic Search

In Venezuela, whenever the oil income has risen, efforts have been made to revert the concentration of population. This strategy is caused by a supposed hyper concentration of population that is questionable when compared to international indicators. The actual government of Venezuela copies these previous attempts. It promotes new axis of development with huge inversions; even though the distributive dynamics

53

Seismological Parameters in the Northern Andes, Venezuela  

NASA Astrophysics Data System (ADS)

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 and strain axes is also exhilbited in the spacial distribution of the b-values. Remarkable is especially a zone in the north - eastern part of the study area with a cluster of normal fault events which is congruent with the maximum b-values observed in the b-value map.

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

2001-12-01

54

Brucella suis infections in collared peccaries in Venezuela.  

PubMed

A bacteriologic and serologic study was conducted on two ranches in the states of Apure and Guarico, Venezuela for brucellosis in collared peccaries (Tayassu tajacu). One hundred thirty-nine peccaries were necropsied and tissues were cultured. Forty-three isolations of Brucella suis biovar 1, were made from lymph nodes and spleens of 25 males and 18 females. Antibody to Brucella sp. was detected in sera from 122 animals by the rapid plate agglutination, standard tube agglutination, 2-mer-captoethanol, rivanol, complement fixation and card tests. Young animals had infection and reactor rates nearly as high as the older animals indicating most were infected at a relative early age. Results suggest that this species may transmit brucellosis when living with domestic animals. This is the first report of B. suis biovar 1 from collared peccaries in Venezuela. PMID:1920669

Lord, V R; Lord, R D

1991-07-01

55

A biostratigraphic sequence analysis in Cretaceous sediments from Eastern Venezuela  

SciTech Connect

This paper presents the results of a high resolution biostratigraphic study integrated with petrophysic analyses, of the Late Cretaceous sequence in several wells from the Maturin Sub-Basin, Eastern Venezuela. The main objective of this study is to integrate the different faunal and floral assemblages to the sedimentological evolution of the basin using sequential analysis techniques. This technique was applied using mainly terrestrial and marine palynomorphs which were relatively abundant and diverse as compared to the scarcity of foraminifera and nonnofossils. Based on the percentages of abundance and the diversity of the different groups of microfoss it was possible to establish the maximum flooding surfaces and condensation levels which allowed the definition of the possible candidates for the sequence boundaries. On the other hand, the identified bioevents made possible the definition of the chronostratigraphic datums of the sequence under study. The results obtained will contribute to optimize the exploration and development programs of the oil fields in Eastern Venezuela.

Paredes, I.; Carillo, M.; Fasola, A.; Luna, F. (Intevep S.A., Caracas (Venezuela))

1993-02-01

56

Experimental life cycle of Philophthalmus gralli (Trematoda: Philophthalmidae) in Venezuela.  

PubMed

Descriptions of the miracidium, mother redia, daughter redia, grandaughter redia, cercaria, metacercaria and adult stages of Philophthalmus gralli Mathis and Leger, 1910 recovered from experimental infections are presented. The intermediate host, Melanoides tuberculata, was collected from freshwater rivulets in Aguasanta and Yaguracual, Sucre State, Venezuela. Chicken were orally infected with cercariae and metacercariae, and metacercariae were introduced directly into the eyes by pipette. Both processes of infection produced adult worms. This is a new geographical record for P. gralli. PMID:12298291

Díaz, Marcos T; Hernández, Luz E; Bashirullah, Abul K

2002-06-01

57

Venezuela bets on heavy crude for long term  

Microsoft Academic Search

In the heart of eastern Venezuela lies the Orinoco Belt, a vast reserve of heavy crudes and bitumen that equate to only 8° to 10° API. At the beginning of the 1920s, a number of foreign companies explored this area. However, they realized that this crude was too heavy to be produced commercially and abandoned their exploratory sites. In 1978--1980,

1997-01-01

58

Sequence stratigraphy of the Maturin sub-basin (Eastern Venezuela)  

Microsoft Academic Search

The prolific Eastern Venezuela Basin has an area of about 160,000 km² and is bounded by the Pilar Fault to the North, the Guayana Shield to the South, the Baul Arch to the West and beyond the Orinoco Delta to the East. Sequence analysis of three N-S and one W-E regional transects covered by over one thousand km of seismic

G. Gonzales; S. Mata; N. Santiago

1996-01-01

59

Use of molluscicides in the control of bilharziasis in Venezuela*  

PubMed Central

The application of molluscicides to the breeding-places of Australorbis glabratus—the intermediate host of Schistosoma mansoni in Venezuela—is discussed, with special reference to the equipment required and the techniques employed. The characteristics of the three molluscicides in use—copper sulfate, sodium pentachlorophenate, and copper pentachlorophenate—are outlined, and the treatment both of running waters (irrigation canals and streams) and of still waters (ponds and marshes) is described in detail.

Jove, Jose Antonio

1956-01-01

60

Ecological observations on Heteropsis Spp. (Araceae) in Southern Venezuela  

Microsoft Academic Search

This article contributes a brief review of the ethnobotany and ontogeny ofHeteropsis spp. (Araceae), reports the distribution and density of Heteropsis spp. in a tropical lowland rainforest in southern Venezuela,\\u000a and explores the environmental variables that correlate best with the observedHeteropsis densities.Heteropsis occurred on 26% of the 4091 trees (?10 cm DBH) inventoried in 67 plots (of 0.1 hectare, each).

Claudia Knab-Vispo; Bruce Hoffman; Timothy Moermond; Conrad Vispo

2003-01-01

61

Cretaceous to Eocene passive margin sedimentation in Northeastern Venezuela  

Microsoft Academic Search

Twenty two palinspastic paleogeographic maps are presented for the Cretaceous to Eocene strata of the Serrania del Interior of northeastern Venezuela. The mapped lithologies, environmental conditions, and evolving depositional systems record [approximately]90 m.y. of dominantly marine sedimentation on the only observable Mesozoic passive margin in the Western Hemisphere. The depositional systems of the passive margin are heterogeneous at lateral (i.e.,

1993-01-01

62

Radioisotope Concentration in Lake Sediments of Maracaibo, Venezuela  

NASA Astrophysics Data System (ADS)

Maracaibo Lake is one of the most important water basing and oil producing regions in Venezuela. Changes in the local environment have been monitored for chemical pollution in the past. For this study we selected a set of sediment samples collected in the shore and analyzed for its radioisotope content. Results show the gamma emitting isotopes distribution. Isotopes concentrations have been determined within the natural K, Th and U families.

Salas, A. Rangel; Viloria, T.; Sajo-Bohus, L.; Barros, H.; Greaves, E. D.; Palacios, D.

2007-10-01

63

Venezuela and Education Transformation for the Development of the People  

Microsoft Academic Search

\\u000a To write about education in Venezuela in only one chapter is indeed challenging, maybe even more challenging than the huge\\u000a changes that have occurred in the education system especially in the last ten years. Before 1999, there were changes marked\\u000a by the country’s historical development (López de D’Amico and González 2006), nevertheless the changes that have taken place\\u000a in the

Rosa López de D’Amico; Maritza Loreto; Orlando Mendoza

64

Low Cost Feeding Strategies for Dual Purpose Cattle in Venezuela  

Microsoft Academic Search

ABSTRACT This simulation study was to evaluate low cost feeding strategies in response to higher cost of commercial,concentrates to maintain,current milk,sales from,dual purpose,cattle herds in the humid,low- lands of western,Venezuela. Data were from,farm,surveys,in 1987 and,1988. Baseline net margins from milk and beef per cow per year were $132 and $99 for two farm cases with average daily milk of 10

P. W. Townsend; R. W. Blake; F. J. Holmann; P. J. Van Soest; C. J. Sniffen; D. G. Sisler

1990-01-01

65

Diversified techniques are key to successful Venezuela operation  

Microsoft Academic Search

Texas Petroleum Co.'s Mata field is an 84,453-acre concession separated into 3 blocks that contain a total of 463 reservoirs. It is one of E. Venezuela's major fields and currently produces an average of 22,500 bpd. Production is highly diversified, i.e., natural flow, gas lift, hydraulic pump, and rod pumping. Crude gravities range from 10° to 50° API, so production

J. C. Acosta; F. D. Verde

1975-01-01

66

Preliminary survey of Cacajao melanocephalus melanocephalus in Southern Venezuela  

Microsoft Academic Search

We conducted a survey of Cacajao melanocephalus melanocephalusin southern Amazonas, Venezuela, to update information on their distribution and to select a site for a longitudinal study.\\u000a We surveyed along the Rio Negro, Brazo Casiquiare, Rio Pasimoni, and Rio Baria and interviewed local people. We observed C. m. melanocephalusfour times along the Rio Pasimoni (N =2)and the Rio Baria (N =2).Group

Shawn M. Lehman; Kimberly L. Robertson

1995-01-01

67

Radioisotope Concentration in Lake Sediments of Maracaibo, Venezuela  

SciTech Connect

Maracaibo Lake is one of the most important water basing and oil producing regions in Venezuela. Changes in the local environment have been monitored for chemical pollution in the past. For this study we selected a set of sediment samples collected in the shore and analyzed for its radioisotope content. Results show the gamma emitting isotopes distribution. Isotopes concentrations have been determined within the natural K, Th and U families.

Salas, A. Rangel; Viloria, T. [La Universidad del Zulia (Venezuela); Sajo-Bohus, L.; Barros, H.; Greaves, E. D.; Palacios, D. [Universidad Simon Bolivar (Venezuela)

2007-10-26

68

Update on Chagas disease in Venezuela: a review  

Microsoft Academic Search

The present article reviews the status of Chagas disease in Venezuela based on the detection of Trypanosoma cruzi infections both in referred patients with clinical presumptive diagnosis (1988-2002) and in individuals sampled from rural localities representative of the different geographical regions of the country (1995-2002). In the former group from 306 individuals examined, 174 (56.8%) were seropositive to T. cruzi;

Néstor Añez; Gladys Crisante; Agustina Rojas

2004-01-01

69

Diversity and composition of dengue virus type 2 in Venezuela.  

PubMed

Dengue is a mosquito-borne disease caused by four closely related dengue virus (genus Flavivirus)serotypes (DENV-1–4). The clinical outcomes vary from mild febrile illness to life-threatening haemorrhagic manifestations. DENVs are endemic in the tropics and subtropics globally and currently no specific treatment or vaccines are available. In Venezuela, the American-Asian genotype of DENV-2 is the most prevalent and has been associated with severe disease outcomes.We aimed to follow-up the molecular epidemiology of DENV-2 in Venezuela to investigate if the evolution of the virus has remained the same throughout time or if the same dynamics documented in Brazil (hyperendemic co-circulation) also occurred. The results show that whereas the epidemiology of DENV in several endemic areas is characterized by serotype replacements through time, in Venezuela the American-Asian genotype DENV-2 has evolved into several genetic lineages and has remained in hyperendemic co-circulation with the other serotypes. PMID:23110744

Huhtamo, E; Comach, G; Sierra, G; Camacho, D E; Sironen, T; Vapalahti, O; Uzcátegui, N Y

2012-10-31

70

Egalitarian policies and social determinants of health in Bolivarian Venezuela.  

PubMed

In 1999, newly-elected Venezuelan President Hugo Chávez initiated a far-reaching social movement as part of a political project known as the Bolivarian Revolution. Inspired by the democratic ideologies of Simón Bolívar, this movement was committed to reducing intractable inequalities that defined Venezuela's Fourth Republic (1958-1998). Given the ambitious scope of these reforms, Venezuela serves as an instructive example to understand the political context of social inequalities and population health. In this article, we provide a brief overview of the impact of egalitarian policies in Venezuela, stressing: (a) the socialist reforms and social class changes initiated by the Bolivarian Movement; (b) the impact of these reforms and changes on poverty and social determinants of health; (c) the sustainability of economic growth to continue pro-poor policies; and (d) the implications of egalitarian policies for other Latin American countries. The significance and implications of Chávez's achievements are now further underscored given his recent passing, leading one to ask whether political support for Bolivarianism will continue without its revolutionary leader. PMID:24066420

Muntaner, Caries; Benach, Joan; Páez Victor, María; Ng, Edwin; Chung, Haejoo

2013-01-01

71

Was the Apertura Petrolera in Venezuela beneficial from the economical perspective?  

Microsoft Academic Search

The process of private participation of the oil industry in Venezuela, known as Apertura Petrolera (AP), progressed for a few years until the end of 1998 when national elections brought to power a new administration with different intentions for the oil industry, then the process halted. Venezuela's oil industry performance affects, to a large degree, the country's economy due to

Jose Rafael Duque Ramirez

72

Correlation of the Jurassic through Oligocene Stratigraphic Units of Trinidad and Northeastern Venezuela  

Microsoft Academic Search

The Jurassic through Oligocene stratigraphies of Trinidad and the Serrania del Interior of eastern Venezuela exhibit many similarities because of their proximity on the passive continental margin of northeastern South America. A slightly later subsidence in eastern Venezuela, and the generally deeper-water sedimentation in Trinidad, is interpreted to be the result of a serration of the original rift margin, producing

Sam Algar; Johan P. Erikson

1995-01-01

73

LIVESTOCK FACILITIES AND POLLUTION OF WATER RESOURCES IN VENEZUELA: CURRENT STATUS  

Microsoft Academic Search

SUMMARY The main objective of this paper was to analyze the current status of the relationship between livestock facilities in Venezuela and the pollution they can cause to water resources used for human or animal consumption. Briefly, it is informed about the geographic and economical situation in Venezuela, and about the high risks of ecosystems contamination with products derived from

Roy D. Meléndez; Yolanda Romero-Cazeaudumec; Francisco Blavia

74

PERCEPCIÓN DEL VALOR NUTRICIONAL Y PREFERENCIAS DE ALIMENTOS EN ESCOLARES DE QUINTO GRADO. MÉRIDA, VENEZUELA  

Microsoft Academic Search

Perception of nutritional value and preferences of foods in primary school children. Mérida. Venezuela. A nutritional questionnaire was applied to a sample of fifth-grade school children attending school in Mérida, Venezuela. Two-hundred and eleven children were asked to evaluate the perceived nutritional value as well as their personal preference for a variety of prepared food groups. The results showed that

Pedro López; Luis Esqueda; Fernando Rivas; Rosalba Chacón; Armando Buccé

75

Venezuela positioning itself to take key market role in wake of Gulf War  

SciTech Connect

This paper reports on Venezuela which continues efforts to position itself in world markets to capitalize on fallout from the Persian Gulf war. The central government and state oil company Petroleos de Venezuela SA have accelerated already ambitious plans to expand activities in upstream and downstream oil and gas sectors. Pvdsa has sharply increased its 1991-96 investment program from the level planned at the end of last year. The goal is to put Venezuela on a par with major Persian Gulf oil exporters in terms of productive capacity. Linchpin of those efforts could well be further steps toward privatization of Venezuela's oil sector. For the first time since nationalization in 1976, private foreign and domestic companies are being permitted to participate in Venezuelan exploration and development. In addition, the government is trimming the onerous tax burden the oil sector has carried in Venezuela, as well as its heavy subsidy of domestic petroleum products.

Not Available

1991-08-19

76

Hydrocarbon systems of Northeastern Venezuela: plate through molecular scale-analysis of the genesis and evolution of the Eastern Venezuela Basin  

Microsoft Academic Search

The prolific, oil-bearing basins of eastern Venezuela developed through an unusual confluence of Atlantic, Caribbean and Pacific plate tectonic events. Mesozoic rifting and passive margin development created ideal conditions for the deposition of world-class hydrocarbon source rocks. In the Cenozoic, transpressive, west-to-east movement of the Caribbean plate along the northern margin of Venezuela led to the maturation of those source

L. L Summa; E. D Goodman; M Richardson; I. O Norton; A. R Green

2003-01-01

77

Venezuela No. 1 oil import source in S. America  

SciTech Connect

This paper reports that with the exception of Venezuela, the U.S. is likely to import much oil from South American countries through 2010, the General Accounting Office reports. GAO, a congressional watchdog agency, noted the U.S. imports about 4% of its oil from Colombia, Ecuador, and Trinidad and Tobago and possibly could import from Argentina, Bolivia, Brazil, Chile, and Peru in the future. It the the eight countries' crude oil reserves are expected to increase about 30% by 2000, then slide about 2% by 2010. Their oil production is expected to climb about 21% over 1990 by 2000, then level off until 2010.

Not Available

1992-08-10

78

José María Vargas (1786-1854): Reformer of Anatomical Studies in Venezuela.  

PubMed

José María Vargas (1786-1854): Venezuelan medical doctor, surgeon, optician, anatomist, chemist, botanist, professor, geologist, mineralogist, and mathematician. Second President of Venezuela (1835-1836), First republican dean, he reformed medicine studies in 1827 establishing human anatomical dissection in the Universidad Central de Venezuela where he taught human anatomy between 1827 and 1853 along with surgery and chemistry. In 1838, he wrote Curso de Lecciones y demostraciones Anatómicas, the first book on the subject printed in Venezuela for the teaching of human anatomy. Clin. Anat., 2013. © 2013 Wiley Periodicals, Inc. PMID:23650143

Reverón, Rafael Romero

2013-05-01

79

Renal diseases in children in Venezuela, South America.  

PubMed

The present study reports epidemiological data on renal disorders in children in Venezuela. Information was obtained from 14 centers for the period January through December 1998. A total of 3,624 patients were evaluated as either a first outpatient consultation or as a first hospital admission. Nearly 70% of the patients could be grouped in one of the following categories: (1) urinary tract infections (32%), with detection of abnormalities of the urinary tract in 25%, (2) metabolic disorders (28%), mainly idiopathic hypercalciuria and hyperuricosuria, (3) glomerulonephritis (9.5%). The other 30% corresponded to urolithiasis 7%; renal tubular acidosis 5.6%; nephrotic syndrome 4.5%; primary hematuria 4.2%; acute renal failure 2.8% (43% were secondary to acute dehydration, 15% to birth asphyxia, 14% to septicemia, and 23% to multiple factors); chronic renal failure 1.6% (secondary to glomerulopathies, predominantly focal glomerulosclerosis, structural abnormalities of the urinary tract, hereditary disorders, and renal hypoplasia/dysplasia); miscellaneous diseases 4.8%. Hence, the spectrum of renal disorders in Venezuela is wide, sharing similarities with countries of both the developed and developing world. These data will hopefully contribute to the development of national healthcare policies appropriate to the epidemiology of the country. PMID:12172777

Orta-Sibu, Nelson; Lopez, Michelle; Moriyon, Juan C; Chavez, Juan B

2002-06-07

80

Tectonic significance of paleomagnetic data from northern Venezuela  

NASA Astrophysics Data System (ADS)

A paleomagnetic study, mostly of basic intrusive rocks of Cretaceous and Tertiary age from northern Venezuela, includes 153 samples from 31 sites, of which only 6 sites failed to give consistent results. Fifteen sites within the Caribbean Mountains have easterly declinations with shallow, mixed positive and negative inclinations. These anomalous vectors are interpreted to be the result of tectonic rotation about vertical axes rather than to reflect anomalous magnetic field orientations associated with a polarity transition. Although these sample sites are within igneous intrusive bodies with no control on the original attitude during acquisition of the natural remanent magnetization, the relative conformity of data from numerous separate intrusions requires an average 90° megatectonic rotation of both the Villa de Cura and Tinaco tectonic belts of the Caribbean Mountains. On the other hand, seven sites from the Paraguana Peninsula (and two sites from the younger Tertiary Falcon basin) have southerly declination and positive inclination. These vectors can be explained by rotation about horizontal east-west axes during Cenozoic folding. A compilation of available paleomagnetic data from rocks of Cretaceous age in the Caribbean indicates that anomalous declinations are widespread in both the Greater Antilles and Caribbean Mountains. We interpret these data to support previous suggestions of megatectonic rotations of a more linear, north-south trending Mesozoic island arc system that included portions of the Greater Antilles and Caribbean Mountains of Venezuela.

Skerlec, G. M.; Hargraves, R. B.

1980-10-01

81

Pyrolysis Kinetics Applied to Prediction of Oil Generation in the Maracaibo Basin, Venezuela.  

National Technical Information Service (NTIS)

We use chemical kinetic parameters for oil generation derived from modified Rock-Eval and Pyromat instruments, coupled with thermal history models, to predict the timing and extent of oil generation in the Maracaibo Basin of Venezuela. The vitrinite refle...

J. J. Sweeney S. Talukdar A. K. Burnham C. Vallejos

1989-01-01

82

Biosynthesis of plant-specific flavones and flavonols in Streptomyces venezuelae.  

PubMed

Recently, recombinant Streptomyces venezuelae has been established as a heterologous host for microbial production of flavanones and stilbenes, a class of plant-specific polyketides. In the present work, we expanded the applicability of the S. venezuelae system to the production of more diverse plant polyketides including flavones and flavonols. A plasmid with the synthetic codon-optimized flavone synthase I gene from Petroselium crispum was introduced to S. venezuelae DHS2001 bearing a deletion of the native pikromycin polyketide synthase gene, and the resulting strain generated flavones from exogenously fed flavanones. In addition, a recombinant S. venezuelae mutant expressing a codon-optimized flavanone 3beta-hydroxylase gene from Citrus siensis and a flavonol synthase gene from Citrus unshius also successfully produced flavonols. PMID:20890094

Park, Sung Ryeol; Paik, Ji Hye; Ahn, Mi Sun; Park, Je Won; Yoon, Yeo Joon

2010-09-01

83

Biological and phylogenetic characterization of a genotype VII Newcastle disease virus from Venezuela: Efficacy of vaccination  

Technology Transfer Automated Retrieval System (TEKTRAN)

Here we describe the characterization a virulent genotype VII Newcastle disease virus (NDV) from Venezuela and evaluate the efficacy of heterologous genotype commercial vaccination under field and controlled rearing conditions. Biological pathotyping and molecular analysis were applied. Results sh...

84

Characterization of antigenetic serotypes from the dengue virus in Venezuela by means of Grid Computing.  

PubMed

This work determines the molecular epidemiology of dengue virus in Venezuela by means of phylogenetic calculations performed on the EELA-2 Grid infrastructure with the PhyloGrid application, an open source tool that allows users performing phylogeny reconstruction in their research. In this study, a total of 132 E nucleotide gene sequences of dengue virus from Venezuela recorded in GenBank(R) have been processed in order to reproduce and validate the topology described in the literature. PMID:20543442

Isea, Raúl; Montes, Esther; Rubio-Montero, Antonio J; Rosales, José D; Rodríguez-Pascual, Manuel A; Mayo, Rafael

2010-01-01

85

Canine visceral leishmaniasis on Margarita Island (Nueva Esparta, Venezuela).  

PubMed

The frequency of American visceral leishmaniasis affecting humans on Margarita Island, Venezuela, has increased in recent years, and infected dogs appear to constitute the principal source of infection. ELISA tests with Leishmania donovani promastigotes and rK39 antigen from L. chagasi in serum from 541 dogs were positive in 33.1% and 21.6% of the samples, respectively. A second blood sample taken from 50 animals after 8-10 months revealed an increase from 24% to 40% of ELISA positivity to both antigens, suggesting high susceptibility and transmission in the canine population. Among 42 serologically positive dogs, 33% of which showed clinical signs of disease, 79% were positive in polymerase chain reactions using primers specific for the L. donovani complex. Control measures including epidemiological hypersurveillance, the humane sacrifice of infected dogs, and rapid diagnosis and treatment of human cases have been initiated. PMID:11132371

Zerpa, O; Ulrich, M; Negrón, E; Rodríguez, N; Centeno, M; Rodríguez, V; Barrios, R M; Belizario, D; Reed, S; Convit, J

86

Transmission of Guanarito and Pirital Viruses among Wild Rodents, Venezuela  

PubMed Central

Samples from rodents captured on a farm in Venezuela in February 1997 were tested for arenavirus, antibody against Guanarito virus (GTOV), and antibody against Pirital virus (PIRV). Thirty-one (48.4%) of 64 short-tailed cane mice (Zygodontomys brevicauda) were infected with GTOV, 1 Alston’s cotton rat (Sigmodon alstoni) was infected with GTOV, and 36 (64.3%) of 56 other Alston’s cotton rats were infected with PIRV. The results of analyses of field and laboratory data suggested that horizontal transmission is the dominant mode of GTOV transmission in Z. brevicauda mice and that vertical transmission is an important mode of PIRV transmission in S. alstoni rats. The results also suggested that bodily secretions and excretions from most GTOV-infected short-tailed cane mice and most PIRV-infected Alston’s cotton rats may transmit the viruses to humans.

Milazzo, Mary L.; Cajimat, Maria N.B.; Duno, Gloria; Duno, Freddy; Utrera, Antonio

2011-01-01

87

Hepatitis C virus infection in hemodialysis patients in Maracaibo, Venezuela.  

PubMed

Over a two year period, the incidence of hepatitis C virus (HCV) infection was evaluated in 29 hemodialysis patients, aged between 15 and 75 years (mean ± SD: 45 ± 39.5 years), from the University Hospital Hemodyalisis Unit, Maracaibo, Zulia State, Venezuela. Anti-HCV antibodies were determined using a fourth generation ELISA (Innotest HCV Ab IV) kit and positive blood samples were tested using a recombinant assay kit (Inno-LIA HCV Ab III), both kits from Innogenetics N.V., Belgium. The findings indicate a lack of HCV seroconversion in the hemodialysis patients over the study period, confirmed by the recombinant assay. Risk factors for HCV infection were 0.3270 (95% confidence interval: 0.01323-8.080) in patients undergoing hemodialysis. The findings suggest a lack of significant sources for HCV infection due to the preventive measures to avoid its transmission in the hemodialysis unit. PMID:22370755

Monsalve-Castillo, Francisca; Gómez-Gamboa, Liliana; Chacín-Bonilla, Leonor; Porto-Espinoza, Leticia; Costa-León, Luciana

88

[Molecular identification of bovine enteric calciviruses in Venezuela].  

PubMed

Caliciviruses are a well-established cause of respiratory, vesicular and hemorrhagic diseases in animals. In addition, these viruses are an important cause of enteric diseases in humans. Recently, molecular analysis of several bovine enteric calicivirus isolates indicated that they are genetically close to human enteric calicivirus. To investigate if bovine enteric caliciviruses circulate in Venezuela, 129 stool samples collected between 1994 and 2000 were assayed by reverse transcription-polymerase chain reaction amplification. The presence of calicivirus was confirmed in one of the samples analyzed, collected in the Lara State from a healthy calf, 2 months old. Phylogenetic studies based on partial RNA polymerase sequences indicated that the Venezuelan isolate (Bo/NV/Lara/2000/VE) is most closely related to the genogroup III, genus Noroviruses. PMID:14976786

Alcalá, Ana C; Hidalgo, Mayra A; Obando, César; Vizzi, Esmeralda; Liprandi, Ferdinando; Ludert, Juan E

2003-01-01

89

Geology and geochemistry of crude oils, Bolivar coastal fields, Venezuela  

SciTech Connect

The Bolivar Coastal Fields (BCF) are located on the eastern margin of Lake Maracaibo, Venezuela. They form the largest oil field outside of the Middle East and contain mostly heavy oil with a gravity less than 22/sup 0/ API. Thirty crude oils from the BCF were collected along two parallel and generally southwest-northeast trends. These oils were characterized by their API gravity, percent saturates, aromatics, NSO and asphalitic compounds, gas chromatograms for whole oils, C/sub 4/-C/sub 7/ fractions, and aromatics. Also, 24 associated waters were sampled and analyzed for Ca/sup + +/, Mg/sup + +/, Na/sup +/, HCO/sub 3//sup -/, CO/sub 3//sup - -/, SO/sub 4//sup - -/, pH, and total dissolved solids (TDS). The geological and geochemical significances of these analyses are discussed with particular emphasis on the genesis of the petroleum.

Bockmeulen, H. (Inst. Techologico Venezolano del Petroleo, Los Teques, Venezuela); Barker, C.; Dickey, P.A.

1983-02-01

90

Embodying racism: race, rhinoplasty, and self-esteem in Venezuela.  

PubMed

In this article, I examine how race motivates women's decisions to undergo aesthetic rhinoplasty in Caracas, Venezuela. Through a combination of cultural domain analysis and thematic analysis of qualitative interviews, I explore how the preference for whiteness and associated facial features dovetail with the aesthetic ideals promoted by cosmetic surgeons. Rhinoplasty is offered by physicians and interpreted by patients as a resolution to body dissatisfaction and low self-esteem. The clinical ethos of objectivity established by cosmetic surgeons fails to acknowledge how perceptions of the self and body are strongly tied to racial marginalization: patients' efforts to alter the nose reveal attempts to change not only how the body looks, but how it is lived. As a result, cosmetic surgery only acts as a stop-gap measure to heighten one's self-esteem and body image. PMID:23349127

Gulbas, Lauren E

2012-11-30

91

The National Seismological Network of Venezuela, Future Aims and Goals  

NASA Astrophysics Data System (ADS)

The Venezuelan coastline mainly coincides with the plate tectonic boundary between the Caribbean and South American plate. The relative movement is accomodated in numerous west - east trending sub-parallel faults. The Venezuelan Andes are dominated by the broad southwest-northeast trending Bocono fault system. This plate tectonic setting causes a wide range of seismic activity in Venezuela. Among the various phenomenons which can be observed are micro seismicity, ranging from magnitude 1 to 3, earthquake swarms with large numbers of small scale events concentrated in specific areas and last but not least macro seismic activity with earthquakes of magnitudes larger than 6 including the consequent aftershock sequences. The most recent destructive earthquake of Mw=6.9 on July 9th, 1997 near the villages of Cariaco and Casanay in the north eastern coastal region, gave way to the project of the modernization of the national seismological network of Venezuela, funded by the Venezuelan government and operated by FUNVISIS (Venezuelan Foundation of Seismological Research). The new network will consist of 35 broadband seismic stations of which 8 are running up to now. Data transfer is realized by satellite links, each station broadcasting continously with a sample rate of 100 samples/s to the central site in FUNVISIS (Caracas) where the data gets processed and analysed. The general concept includes also local networks with short period seismometers and an extended accelerograph network. We would like to present future aims and goals of the new network: making available complete seismological catalogues and bulletins, including local networks to apply high resolution methods to the achieved data sets, contributing to global seismology.

Orihuela, N.; Rendon, H.; Romero, G.; Lopez, R.; Sobiesiak, M.; Ottemoeller, L.; Tovar, G.

2001-12-01

92

FLORA MARINA DE LA PENÍNSULA DE MACANAO, ISLA DE MARGARITA, VENEZUELA. I. CHLOROPHYTAY PHAEOPHYCEAE Marine flora of the Peninsula of Macanao, Margarita Island, Venezuela. I. Chlorophyta and Phaeophyceae  

Microsoft Academic Search

A taxonomic study of the benthic marine algae of the phylum Chlorophyta and the class Phaeophyceae is given for the Peninsula of Macanao, Margarita Island, Venezuela. Twenty six species are described that represent new records for the area, enlarging the phycofloristic catalog of the region and the range of national distribution of the taxa. Com- plete diagnostic description and figures

Paola PARDO; María A. SOLÉ

2007-01-01

93

Cross sector partnership results in increased marine biodiversity information, awareness, and an initial biodiversity action plan in the Gulf of Paria, Venezuela  

Microsoft Academic Search

This paper describes how a pro-active cross sector partnership between organizations has successfully contributed to a better understanding of marine biodiversity and consensus among stakeholders on conservation priorities in the Gulf of Paria, Venezuela. ConocoPhillips Venezuela and its partners discovered offshore oil resources in the Gulf of Paria, northeastern Venezuela in 1999, and have since been making progress on their

F. D. Rodriguez; A. S. Carter; A. D. Rawa

2005-01-01

94

Innovative security assessment during the facility design stage: protecting people, assets and the marine environment in the Gulf of Paria, Venezuela  

Microsoft Academic Search

This paper explains how ConocoPhillips Venezuela adapted existing methodology to respond Venezuelan and international security regulations by completing an innovative security vulnerability assessment (SVA) of planned offshore facilities and activities in the Gulf of Paria, northeastern Venezuela. Following the discovery of offshore oil resources in the Gulf of Paria, northeastern Venezuela in 1999, ConocoPhillips and its partners began planning operations

F. D. Rodriguez; J. Betancourt; W. Perry

2005-01-01

95

Mapa Geologico de Venezuela a Escala 1:750,000  

USGS Publications Warehouse

Se presenta un mapa geologico digital de Venezuela sobre un fondo de relieve sombreado. Los datos geologicos e hidrologicos del norte del rio Orinoco proceden de la digitalizacion de mapas geologicos en papel a escala 1:500.000. Estos datos fueron integrados con el mapa geologico digital del Escudo de Guayana Venezolano, a su vez derivado de hojas en papel a escala 1:500.000. La informacion sobre los tipos de fallas mostrados en el mapa es igual que en las fuentes originales. Los poligonos geologicos fueron atribuidos por edad, litologia y nombre de la unidad siguiendo el Codigo geologico de Venezuela. Se incorporaron revisiones significativas de la geologia de la Cordillera de la Costa a partir de las nuevas hojas integradas a escala 1:25.000. Toda esta informacion geologico-estructural se sobrepuso a una imagen de relieve sombreado, producida por el procesamiento de los datos de radar interferometrico con 90 m (3 arcosegundos) de resolucion espacial obtenidos por la mision topografica de radar del transbordador espacial (SRTM). Las areas de la base de datos del SRTM carentes de informacion fueron llenadas por medio de la interpolacion de los datos de las celdas adyacentes. Para producir la imagen de relieve sombreado se uso una direccion de iluminacion de 315 deg con un angulo de 65 deg sobre el horizonte. La proyeccion usada en el mapa es conica equidistante, con latitudes de 4 y 9 deg norte como paralelos estandar y una longitud de 66 deg al oeste como meridiano central. Los datos en el mapa proceden primordialment de hojas a escala 1:500.000 y el producto esta preparado para una impresion optima en escala 1:750.000. Los usuarios pueden obtener ampliaciones mayores, sin embargo no se garantiza la precision del mapa a escalas mas detalladas. Especialmente en la region de Guayana, al sobreponer los mapas geologicos sobre la reciente imagen SRTM, se notan grandes discrepancias no sistematicas tanto en contactos como en fallas. Esto es debido a que los mapas geologicos de Guayana tienen como base topografica las imagenes de radar de vision lateral (SLAR), con muy control de campo de los a?os 1970's. La correccion de estos desfases esta planificada para el futuro.

Hackley, Paul C.; Urbani, Franco; Karlsen, Alex W.; Garrity, Christopher P.

2006-01-01

96

EFECTO DE LA APLICACIÓN DE RESIDUOS ORGÁNICOS SOBRE EL CULTIVO DEL MAÍZ EN SUELOS DEGRADADOS DEL ESTADO YARACUY, VENEZUELA  

Microsoft Academic Search

Effect of applications of organic residues on maize performance in two soils of Yaracuy State, Venezuela The intense land cultivation for maize cropping on the last 50 years in Yaracuy State, Venezuela, caused an accelerated soil degradation expressed by loss of soil organic matter and crop productivity. With the objective of improving those parameters, the use of organic residues were

Isabel Arrieche; Orlando Mora

2005-01-01

97

Florística y fisonomía de un matorral xerófilo espinoso intervenido en Punta de Piedras, Municipio Miranda, Estado Zulia, Venezuela  

Microsoft Academic Search

Floristic and physiognomic characteristics of disturbed thorny xerophytic scrubland in Punta de Piedras, Miranda Municipality, Zulia State, Venezuela. We determined the floristic and physiognomic aspects of disturbed thorny xerophytic scrubland in Punta de Piedras, Miranda Municipality, Zulia State, Venezuela. Botanical sampling was done twice monthly (November 2005-June 2006), in both rainy and dry seasons, for a total of 16 samples.

Antonio Vera; Maritza Martínez; Yin Ayala; Sadieth Montes; Anderson González

2009-01-01

98

Clockwise block rotations in the Perija Mountains, Venezuela  

SciTech Connect

Paleomagnetic analyses of Mesozoic sedimentary rocks (8 sites, 115 samples) from the Perija Mountains, Venezuela, yield well-grouped directions of both polarities. Fold tests imply that the magnetization of the Jurassic La Quinta Formation is pre-mid-Cretaceous in age and that the Lower Cretaceous Cogollo Group acquired its magnetization prior to its mid-Tertiary deformation. These data as well as the results from the Cretaceous Apon and La Luna Formations yield consistent northeast or southwest declinations and inclinations corresponding to the present latitude of the sampling area. The clockwise rotations indicated by these data are interpreted to be the result of rotation of fault-bounded blocks in a left-lateral strike-slip zone. Faults such as the Cogollo, La Ge, and Totumo faults which intersect the Perija-Tigre fault at low angles, had initially a north-northwest strike. The Late Oligocene northwest-southeast compression which initiated the uplift of the Perija Mountains rotated these faults to their present north-northeast orientation imparting the observed left-lateral slip. Our paleomagnetic data measure the corresponding rotation of the fault-bounded blocks. Model calculations suggest that a displacement on these faults of less than ten kilometers would be sufficient to cause the observed approximately 45[degrees] clockwise rotations.

Gose, W.A. (Univ. of Texas, Austin (United States)); Perarnau, A. (Intevep, Los Teques (Venezuela)); Castillo, J. (Universidad Simon Bolivar, Caracas (Venezuela))

1993-02-01

99

Meningoencephalitis by Naegleria fowleri: epidemiological study in Anzoategui state, Venezuela.  

PubMed

A case of primary amoebic meningoencephalitis produced by Naegleria fowleri was diagnosed in the Independencia county of Anzoategui State, Venezuela. This case motivated the realization of the present epidemiological study with the aim of identifying free-living amoebae in this area. Representative water samples were taken and physicochemical and microbiologic analyses were carried out. Trophozoites and cysts of Naegleria spp, were detected in 44.4% (n=4). An excellent concordance was found among the observations of free-living amoebae in smears and those of monoxenic cultures in non-nourishing agar with Klebsiella pneumoniae (Kappa=1; p= 0.003). A variable load of aerobic mesophils was obtained. Moulds and yeast averages presented 3.0 CFU/ml (SD +/- 2.0) and 102.9 CFU/ml (SD +/- 32.2), respectively. One hundred per cent of the samples presented a most probable number of total and fecal coliforms of 240,000 NMP/100mL. Naegleria spp was present in waters of the Independence county of Anzoategui state, which constitutes a risk for people that use these sources. PMID:16906250

Cermeño, Julman R; Hernández, Isabel; El Yasin, Helal; Tinedo, Rubén; Sánchez, Raúl; Pérez, Gladys; Gravano, Rosalía; Ruiz, Aida

100

Intestinal Parasitic Infections among Pregnant Women in Venezuela  

PubMed Central

Introduction. Intestinal parasitic infections, especially due to helminths, increase anemia in pregnant women. The results of this are low pregnancy weight gain and IUGR, followed by LBW, with its associated greater risks of infection and higher perinatal mortality rates. For these reasons, in the setting of no large previous studies in Venezuela about this problem, a national multicentric study was conducted. Methods. Pregnant women from nine states were studied, a prenatal evaluation with a coproparasitological study. Univariated and multivariated analyses were made to determine risk factors for intestinal parasitosis and related anemia. Results. During 19 months, 1038 pregnant women were included and evaluated. Intestinal parasitosis was evidenced in 73.9%: A lumbricoides 57.0%, T trichiura 36.0%, G lamblia 14.1%, E hystolitica 12.0%, N americanus 8.1%, E vermicularis 6.3%, S stercoralis 3.3%. Relative risk for anemia in those women with intestinal parasitosis was 2.56 (P<.01). Discussion. Intestinal parasitoses could be associated with conditions for development of anemia at pregnancy. These features reflect the need of routine coproparasitological study among pregnant women in rural and endemic zones for intestinal parasites. Further therapeutic and prophylactic protocols are needed. Additional research on pregnant intestinal parasitic infection impact on newborn health is also considered.

Rodriguez-Morales, Alfonso J.; Barbella, Rosa A.; Case, Cynthia; Arria, Melissa; Ravelo, Marisela; Perez, Henry; Urdaneta, Oscar; Gervasio, Gloria; Rubio, Nestor; Maldonado, Andrea; Aguilera, Ymora; Viloria, Anna; Blanco, Juan J.; Colina, Magdary; Hernandez, Elizabeth; Araujo, Elianet; Cabaniel, Gilberto; Benitez, Jesus; Rifakis, Pedro

2006-01-01

101

Sequence stratigraphy of the Maturin sub-basin (Eastern Venezuela)  

SciTech Connect

The prolific Eastern Venezuela Basin has an area of about 160,000 km{sup 2} and is bounded by the Pilar Fault to the North, the Guayana Shield to the South, the Baul Arch to the West and beyond the Orinoco Delta to the East. Sequence analysis of three N-S and one W-E regional transects covered by over one thousand km of seismic lines and sedimentological, biostratigraphic and electrofacies studies of 80 wells allowed the definition of the sequence stratigraphic column of the basin. Seven major unconformity bounded depositional sequences were defined from Barremian to Recent, three in the Cretaceous and four in the Tertiary. Twenty-one third-order cycles were recognized in the Tejas B supercycle (Upper Oligocene-Recent). This cycle correlates very well with the Gulf of Mexico and Global chronostratigraphic charts. In the proximal, southern area, each sequence shows transgressive sandstones in its lower section and regressive ones in the upper part, separated by claystones that include a maximum flooding surface. In the distal area, fine marine sediments predominate with local turbidities. Some electrical markers and planktonic fossils are traceable over long distances. Regional transacts show two distinct structural zones: tensional to the South and compressional to the North. The best petroleum reservoirs occur in Tertiary and to a lesser extent in Cretaceous sequences. In this basin occurs the largest oil accumulation of the world (Orinoco), as well as several giant oil fields.

Gonzales, G.; Mata, S.; Santiago, N. [Departamento de Geologia, Lagoven, S.A., Caracas (Venezuela)

1996-08-01

102

Cretaceous to Eocene passive margin sedimentation in Northeastern Venezuela  

SciTech Connect

Twenty two palinspastic paleogeographic maps are presented for the Cretaceous to Eocene strata of the Serrania del Interior of northeastern Venezuela. The mapped lithologies, environmental conditions, and evolving depositional systems record [approximately]90 m.y. of dominantly marine sedimentation on the only observable Mesozoic passive margin in the Western Hemisphere. The depositional systems of the passive margin are heterogeneous at lateral (i.e., along-margin) length scales greater than [approximately]40 km. The primary lateral heterogeneity is caused by a major Lower Cretaceous deltaic system that emanated southwest of the Serrania del Interior. All important intervals, such as the laterally variable Aptian-Albian El Cantil platform limestone and the hydrocarbon source rocks of the Upper Cretaceous Querecual and San Antonio formations, are related to probable causal mechanisms and environmental conditions. Stratigraphic events have been interpreted as of either local or regional extent; based on a combination of outcrop sedimentologic analyses and regional depositional systems interpretation. The 3-dimensional distribution of depositional systems and systems tracts reveals 4-6 regional sequence boundaries separated by 4-20 m.y. Subsidence analyses support the facies interpretation of a passive margin by showing continuous, thermally dominated subsidence during the Cretaceous to Eocene interval. Subsidence and accumulation rates increased and facies changed significantly in the Oligocene, indicating the end of passive margin sedimentation and the initiation of foredeep subsidence and accumulation associated with overthrusting the eastward-advancing Caribbean Plate.

Erikson, J.P. (Dartmouth College, Hanover, NH (United States))

1993-02-01

103

Chemostratigraphy: Applications in the Tachira depression, Tachira State, Venezuela  

SciTech Connect

Rock analyses (40 chemical parameters) from densely sampled Cretaceous sections from La Luna, Navay, Aguardiente and Escandalosa formations in southwestern Venezuela, combined with multivariate statistical analysis, allowed statistical characterization of formations, environmentally meaningful clustering of correlated geochemical variables, as well as calculation of chemical accumulation rates. Chemofacies, defined from accumulation rates, were used for correlation and depositional environment definition. Organic matter maturity does not affect NiN ratios, but causes homogenization in Ca/Sr ratios. Th/V ratios clearly separate shelf vs. oceanic fades, closely matching those from biofacies analysis. Cycles in Th/V repeat every 60 in (Navay) to 20 in (La Luna), corresponding to Milankovitch climatic cycles. Shales (high Th/V) represent cooler-shallower sedimentation periods, and lodestones (low Th/V) represent warmer-deeper ones. Differences in accumulation rates were used for establishing changes in: source rock (La-Ce), either due to tectonism or variations in marine current pattern; redox conditions (Ni-V); clay mineralogy (Al-K); energy level (Al-Si); and salinity (Mg-Na). Finally, chemostratigraphy, combined with reliable structural and stratigraphical field data, has proven to be a powerful tool for unravelling tectono-stratigraphical histories.

Briceno, H.; Ostos, M.; Yoris, F. [Caracas (Venezuela)] [and others

1996-08-01

104

Confronting Health Disparities: Latin American Social Medicine in Venezuela  

PubMed Central

Objectives. We explored the emergence and effectiveness of Venezuela's Misión Barrio Adentro, “Inside the Neighborhood Mission,” a program designed to improve access to health care among underserved residents of the country, hoping to draw lessons to apply to future attempts to address acute health disparities. Methods. We conducted our study in 3 capital-region neighborhoods, 2 small cities, and 2 rural areas, combining systematic observations with interviews of 221 residents, 41 health professionals, and 28 government officials. We surveyed 177 female and 91 male heads of household. Results. Interviews suggested that Misión Barrio Adentro emerged from creative interactions between policymakers, clinicians, community workers, and residents, adopting flexible, problem-solving strategies. In addition, data indicated that egalitarian physician–patient relationships and the direct involvement of local health committees overcame distrust and generated popular support for the program. Media and opposition antagonism complicated physicians’ lives and clinical practices but heightened the program's visibility. Conclusions. Top-down and bottom-up efforts are less effective than “horizontal” collaborations between professionals and residents in underserved communities. Direct, local involvement can generate creative and dynamic efforts to address acute health disparities in these areas.

Mantini-Briggs, Clara

2009-01-01

105

[Breeding systems of the Paraguaná coastal plain plants, Venezuela. ].  

PubMed

Breeding systems were evaluated for 51 plant species according to life form, pollination system, vegetation type, and phenology, in the coastal plain of Paraguaná Peninsula, Venezuela. Sexual systems were no associated to life form, pollination system, vegetation type, and phenology. The frequency distribution of sexual system was 82.3% hermaphroditism, 15.6% monoecy, and 1.9% dioecy. All sexual systems had a peak during the lowest rainfall. Genetic system distribution was 64.8% self-compatibility (including partially self-compatibility) and 35.2% self-incompatibility. Among self-compatible species, 45.1% were autogamous (19.6% not autogamous). The genetic systems were associated significantly to: (1) plant life form: self-compatible species tend to be herbaceous and self-incompatible plants tend to be woody species; (2) vegetation type: self-compatible species were predominant in the three vegetation types, but in the mangrove the frequency of self-compatible and self-incompatibles was similar; and (3) pollination system: most of the self-compatible species were polyphilous. Mating systems: xenogamous and autogamous species were associated only with plant life forms. Xenogamous plants were mostly woody species and autogamous plants were mostly herbaceous species. The high incidence of hermaphroditism, self-compatibility, and autogamy are related to herbaceous life form, polyphilous pollination system, and climatic conditions, together the insularity of the Paraguaná peninsula. PMID:17354451

Lemus-Jiménez, Luis José; Ramírez, Nelson

106

Temporal and spatial patterns of malaria reinfection in northeastern Venezuela.  

PubMed

We stratified the risk of malaria transmission (Plasmodium vivax) in 35 villages along a coastal range in northeastern Venezuela (51 km2) where the main vector is the mosquito Anopheles aquasalis. After 20 years without local malaria transmission, reinfection of the entire area occurred from May to December 1985 by local (continuous) and jump (discontinuous) dispersal. Epidemiologic, environmental, and vector variables were investigated with the aid of a Geographic Information System. Risk factors for malaria transmission were human population density, proximity to pre-adult mosquito habitats (< 500 m), and the number of pre-adult habitats nearby. Most inhabitants, immature mosquito habitats, and malaria cases were located at low elevations and on gentle slopes. High prevalence of malaria during the dry seasons was associated with the presence of permanent bodies of water containing An. aquasalis. Occurrence of a La Niña event in 1988 (wet and cool phase of the El Niño Southern Oscillation) triggered malaria transmission to unusually high levels, consolidating infection in the area, and rendering traditional control efforts useless. We recommend tracking malaria persistence per village and associated risk factors as methods to reduce the cost of malaria control programs. PMID:10586913

Barrera, R; Grillet, M E; Rangel, Y; Berti, J; Aché, A

1999-11-01

107

[Susceptibility of Biomphalaria glabrata to Schistosoma mansoni from Venezuela and Brazil].  

PubMed

Schistosoma mansoni partially develops its life cycle into snails of the Family Planorbid. Biomphalaria glabrata represents an important host-intermediate. This paper reports experimental infection with miracidia vs. snail in sympatric and parapatric combination. The infection assay to sympatric combination were: BH snail (Belo Horizonte, Brasil) vs. a common geographic origin parasite, and Barbula, Carabobo State, Venezuela vs. SM Venezuela parasitic. The parapatric combination were: BH snail vs. SM; Barbula vs. BH; Caripe Monagas State, Venezuela vs. SM and Caripe vs. SM. During the study period was observed not miracid penetration. The infection percentage ranged from 88.89% in Barbula vs. SM combination to 0.00% in the Caripe vs. BH and BH vs. SM combination. We concluded which different existence of susceptibility from evaluated combination. PMID:10932760

Moreno Alvarez, M J; Delgado, V

108

Coal bed methane potential in Venezuela-The forgotten resource  

SciTech Connect

In nations already possessing riches of hydrocarbons situated in conventional reservoirs, evaluation of coal-bearing sequences for potential gas is logically delayed or ignored. Nonetheless, Venezuelan coals have long been recognized as stratigraphically associated with oil accumulations, but because coalbed methane (CBM) is a relatively new worldwide phenomenon, CBM potential has not been widely assessed in the country. Two general areas contain vast accumulations of coal for potential CBM activity: (1) the Maracaibo basin, containing the Guasare (northwest), Lobatera-Santo Domingo (southwest) and Urumaco (northeast) districts; and (2) the Oficina basin in eastern Venezuela possessing abundant accumulations related to the Faja Petrolifera de Orinoco (Orinoco Oil Belt). In both basins, high volatile bituminous and lignitic coals of mostly Oligo-Miocene age are abundantly found. Older coals are also present especially in the Maracaibo area. Two factors represent powerful incentives for CBM exploitation: addition of known reserves for economic considerations, and aid in bringing heavy crude oil to the surface by additional gas lift and oil viscosity reduction. Other favorable factors important for CBM methodology include: (1) abundant coals lying above known conventional reservoir targets; (2).6 - 1% vitrinite reflectance measurements in the Orinoco Oil Belt; (3) many coals occurring above 1500 m; (4) documented mine explosions especially in the 1920s and 1930s; (5) a strong tectonic overprint to perhaps add shear fractures to already cleated coals; (6) individual coal thickness up to 12 m with averages in the .8 m range; and (7) gas shows while drilling coal-rich intervals.

Vasquez-Herrera, A.R. [VVA Consultores, Caracas (Venezuela); Bereskin, S.R.; McLennan, J.D. [TerraTek, Inc., Salt Lake City, UT (United States)

1996-08-01

109

The Mexican Sistema de Alerta Sismica (SAS) Experience  

Microsoft Academic Search

The Mexico City's SAS is an Early Warning System developed in accordance with recommendations of foreign and national seismology experts, after the disaster generated in 1985 by the M8.1 Michoacan earthquake. The SAS aim is to help mitigate future seismic disasters in Mexico City (MC), mainly if the big forecast \\

J. Espinosa-Aranda; F. Rodriguez

2003-01-01

110

The Mexican Sistema de Alerta Sismica (SAS) Experience  

NASA Astrophysics Data System (ADS)

The Mexico City's SAS is an Early Warning System developed in accordance with recommendations of foreign and national seismology experts, after the disaster generated in 1985 by the M8.1 Michoacan earthquake. The SAS aim is to help mitigate future seismic disasters in Mexico City (MC), mainly if the big forecast "Guerrero Earthquake" hits. In 1991 the SAS started its service in an experimental basis for evaluating its performance both with a group of basic education students in public schools, and with the emergency stop function for the Mexico City Metropolitan Subway System (METRO of MC); after this The Federal District Government (FDG) opened the SAS as a public service in August, 1993, shortly after the SAS warned, with more than 60 seconds of anticipation, the incoming effect of May 13, 1993, M5.8, and M6 double earthquake originated more than 300 Km from MC between Guerrero and Oaxaca, on the coast. That year, an initial technical flaw generated one false alert signal; the cause was readily corrected. The SAS has 12 seismic sensor stations covering a stripe close to 400 X 100 Km on the Guerrero's coast, between Papanoa and Punta Maldonado, that send information through a dedicated radio relay system to the SAS Central Control in MC., using the valuable support of some TELMEX field installations. Until August, 2003, the SAS sensor system has detected more than 1550 earthquakes in the 2.55 magnitude events, which are the ones felt in MC. The SAS has generated 57 warning signals with an average of 60 sec in advance to earthquake effects: 46 of restricted use for M<6, and 11 of public use for M>6 events. Public warnings have the automatic broadcast support of many commercial radio AM/FM and TV stations in Mexico City and Toluca valleys. The FDG controls the SAS signal service that includes the more frequent events (from M>5 up), asking the user to develop procedures and practice useful actions to mitigate seismic disasters. Each validated SAS seismic warning automatically generates and sends the event information by fax and e-mail to the DFG and Civil Protection Authorities, users and news media; it also sends information about the SAS operating conditions to service technicians, via radio, and phone.

Espinosa-Aranda, J.; Rodriguez, F.

2003-12-01

111

Prey composition in the carnivorous plants Utricularia inflata and U. gibba (Lentibulariaceae) from Paria Peninsula, Venezuela  

Microsoft Academic Search

Carnivorous aquatic plants, genus Utricularia (Lentibulariaceae), capture small aquatic organisms, such as rotifers, copepods, and cladocerans, by means of anatomical structures named bladders. The present study aimed to determine prey size and composition in U. gibba and U. inflata, which were collected from a small lake and an herbaceous wetland, respectively, located in Paria Peninsula (Sucre State, Venezuela). Water pH,

Elizabeth Gordon; Sergio Pacheco

112

The Decision to Call the Police: A Comparative Study of the United States and Venezuela  

Microsoft Academic Search

Cross-national studies of the police have indicated that cultural and attitudinal variables are important determinants of citizens' decision to call the police. In contrast, crime victimization surveys conducted within countries have indicated that crime seriousness is the only important variable. In the present study, data from household surveys conducted in the United States and Venezuela are used to test the

Christopher Birkbeck; Luis Gerardo Gabaldón; Gary LaFree

1993-01-01

113

Rural Development in Venezuela and the Guianas: A Bibliography. Training and Methods Series Number 20.  

ERIC Educational Resources Information Center

|The bibliography cites 930 materials dealing with Venezuela and the Guianas. Published between 1949 and 1972, the materials are found in the Land Tenure Center Library at the University of Wisconsin. Topics covered are: agriculture, agrarian reform, economic affairs, economic cooperation, human resources, American Indians, industry, law, money,…

Anderson, Teresa, Comp.; And Others

114

Nuevas adiciones de algas marinas para el Parque Nacional Mochima, Sucre, Venezuela  

Microsoft Academic Search

The marine algal flora from the eastern coast of Mochima National Park, Sucre, Venezuela was studied with a total of 51 taxa identified, including eight new additions of red algae which are Erythrotrichia carnea (Dillwyn) J. Agardh, Sahlingia subintegra (Rosenvinge) Kornmann, Liagora ceranoides Lamouroux, Asparagopsis taxiformis (Delile) Trevisan, Dasya corymbifera J. Agardh, Chondria dasyphylla (Woodward) C. Agardh, Herposiphonia secunda f.

Soraida Silva; Leonor Brito; Andrés Lemus

115

Geophysical studies for the identification of basin effects in urban areas in Venezuela  

Microsoft Academic Search

Urban areas in northern Venezuela are subject to a moderate seismic hazard due to the interactions between the Caribbean and south American plates, which has been evidenced by historical damaging earthquakes as for example the 1812 and the 1967 earthquakes with a magnitude of 7.2 and 6.5, respectively. Strong damages in Caracas during the 1967 earthquake have been asociated to

M. Schmitz; V. Rocabado; J. Sánchez; C. Reinoza; E. Amaris; C. Cornou

2007-01-01

116

Teachers' Perceived Efficacy among English as a Foreign Language Teachers in Middle Schools in Venezuela  

ERIC Educational Resources Information Center

|Teachers' sense of efficacy has been shown to influence teachers' actions and student outcomes. This study explored self-efficacy beliefs among English as a Foreign Language teachers in selected schools in Venezuela. Data were collected through a survey administered to 100 teachers. The Teacher Sense of Efficacy Scale (Tschannen-Moran & Woolfolk…

Chacon, C.T.

2005-01-01

117

ECOLOGICAL STUDIES OF ENZOOTIC VENEZUELAN EQUINE ENCEPHALITIS IN NORTH-CENTRAL VENEZUELA 1997–1998  

Microsoft Academic Search

Abstract. From 1997–1998, we investigated the possible continuous circulation of epizootic Venezuelan equine encephalitis (VEE) virus suggested by a 1983 subtype IC interepizootic mosquito isolate made in Panaquire, Miranda State, Venezuela. The study area was originally covered by lowland tropical rainforest but has been converted into cacao plantations. Sentinel hamsters, small mammal trapping, mosquito collections, and human serosurveys were used

Rosa Alba Salas; Carmen Z. Garcia; Jonathan Liria; Roberto Barrera; Juan Carlos Navarro; Gladys Medina; Clovis Vasquez; Zoraida Fernandez; Scott C. Weaver

118

Análisis del metabolismo energético y de materiales de Brasil, Chile y Venezuela  

Microsoft Academic Search

El artículo presenta una aplicación de las metodologías de Análisis de Flujo de Materiales y Análisis Integrado Multi- Escala del Metabolismo Social (MSIASM, siglas en inglés) para la caracterización de modelos de desarrollo económico de Brasil, Chile, y Venezuela, mediante la utilización combinada de datos económicos y de uso de energía y materiales para diferentes sectores y en diversos niveles

Nina Eisenmenger; Jesús Ramos Martín; Heinz Schandl

2007-01-01

119

Oblique Collision of the Leeward Antilles, Offshore Venezuela: Linking Onshore and Offshore Data from BOLIVAR  

Microsoft Academic Search

The kinematic history of the Leeward Antilles (offshore Venezuela) can be characterized with the integration of onshore outcrop data and offshore seismic reflection data. Deformation structures and seismic interpretation show that oblique convergence and wrench tectonics have controlled the diachronous deformation identified along the Caribbean - South America plate boundary. Field studies of structural features in outcrop indicate one generation

A. G. Beardsley; H. G. Avé Lallemant; A. Levander; S. A. Clark

2006-01-01

120

Arbuscular mycorrhizas in coastal sand dunes of the Paraguaná Peninsula, Venezuela  

Microsoft Academic Search

Arbuscular mycorrhizal colonization was measured in the most abundant plant species of the Paraguaná Peninsula, northwestern Venezuela. These plant species included: Acacia tortuosa, Argusia gnaphalodes, Croton punctatus, Croton rhamnifolius, Egletes prostrata, Melochia tomentosa, Panicum vaginatum, Scaevola plumieri, Sporobolus virginicus, Suriana maritima, Leptothrium rigidum, and Fimbristylis cymosa. Mycorrhizal colonization was assessed using the Trouvelot et al. (1986) method that allows for

C. Alarcón; G. Cuenca

2005-01-01

121

High resolution paleoclimatic reconstruction of the last deglaciation in the intertropical Cariaco basin (Venezuela)  

Microsoft Academic Search

The aim of this study is a high-resolution reconstruction of the paleoclimate record of the last 16 ka of the Cariaco Basin, using a combination of geochemical and grain-size analyses. The studied core was collected at the ODP site 1002 on the western edge of the central saddle of the basin (off Venezuela). An age model was determined using a

M. Aycard; V. Bout-Roumazeilles; N. Tribovillard; F. Baudin

2003-01-01

122

Late Pleistocene cingulates (Mammalia: Xenarthra) from Mene de Inciarte Tar Pits, Sierra de Perijá, western Venezuela  

Microsoft Academic Search

A new assemblage of Cingulata (Xenarthra) from the late Pleistocene of northwestern Venezuela is reported. The fauna includes Dasypus sabanicola, Propraopus sulcatus, and Pampatherium humboldtii, all three of which are reported for the first time from the Venezuelan Pleistocene. Glyptodon clavipes is also reported. A systematic problem with the species of Propraopus is reported, with a suggestion for the probable

Ascanio D. Rincón; Richard S. White; H. Gregory Mcdonald

2008-01-01

123

The Effect of Wage Compression and Alternative Labor Market Opportunities on Teacher Quality in Venezuela  

ERIC Educational Resources Information Center

|This paper examines the effect of teacher relative wages and teacher wage dispersion on high school graduates' preferences for teaching majors in College. This approximation to teacher quality is appropriate in a country like Venezuela as opposed to the US since the rigidity of the tertiary school system significantly limits mobility between…

Ortega, Daniel E.

2010-01-01

124

TOXOPLASMA GONDII INFECTIONS IN CHICKENS FROM VENEZUELA: ISOLATION, TISSUE DISTRIBUTION, AND MOLECULAR CHARACTERIZATION  

Microsoft Academic Search

The prevalence of Toxoplasma gondii, in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 46 free-range chickens (Gallus domesticus) from Venezuela was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 16

J. P. Dubey; A. Lenhart; C. E. Castillo; L. Alvarez; P. Marcet; C. Sreekumar; T. Lehmann

2005-01-01

125

3D seismic interpretation-Norte de Paria, offshore Eastern Venezuela  

Microsoft Academic Search

During 1991 a 1600 km[sup 2] 3D seismic survey was acquired for the Cristobal Colon Project, a joint venture of Lagoven (33%), Shell (30%), Exxon (29%) and Mitsubishi (8%). The objective is to evaluate the volumes of gas in the Mejillones, Patao, Dragon, and Rio Caribe gas fields, located north of the Paria Peninsula in offshore eastern Venezuela, in order

R. Ramirez de Arellano; L. van Bommel; F. Riart; J. Gil

1993-01-01

126

Counter-Hegemonic Regionalism and Higher Education for All: Venezuela and the ALBA  

ERIC Educational Resources Information Center

|This paper employs new regionalism theory and regulatory regionalism theory in its analysis and theorisation of the Bolivarian Alliance for the Peoples of Our America (ALBA) as a counter-hegemonic Latin American and Caribbean (LAC) regionalism. As (initially) the regionalisation of Venezuela's Bolivarian Revolution, ALBA is centred around the…

Muhr, Thomas

2010-01-01

127

The Universidad Nacional Abierta of Venezuela. A Case Study in Distance Learning Systems.  

ERIC Educational Resources Information Center

|A brief description of the country of Venezuela (geography, population, economy, internal communications, and politics) and its educational system introduce a description of the Universidad Nacional Abierta (UNA). The UNA was opened in July 1978 to expand the national system of higher education by the use of distance learning techniques. These…

Friedman, H. Z.

128

An Innovative Project in Educational Technology: The Panama-Venezuela Project.  

ERIC Educational Resources Information Center

|Describes a project which is being implemented in the field of educational technology in Panama and Venezuela. The project emphasizes inservice training of a cadre of professionals who will direct efforts to identify and resolve significant problems in education. (Author/CHC)|

Rojas, Alicia Mabel

1980-01-01

129

Geological Studies in eastern Venezuela and Trinidad from Cretaceous passive margin to Neogene transpressional thrust belt  

Microsoft Academic Search

Sedimentological and structural analyses of Trinidad's Northern and Central ranges and Venezuela's Serrania del Interior have led to new interpretations of northeastern. South America's tectonic evolution within the Southern Caribbean Plate Boundary Zone. Medial ( ) Jurassic through early Cenozoic passive margin sediments make up the majority of these areas and were deposited somewhat to the WNW (between 80 and

S. T. Algar; J. E. Erikson; J. L. Pindell

1991-01-01

130

Distribution of Lymnaeidae (Mollusca: Pulmonata), intermediate snail hosts of Fasciola hepatica in Venezuela  

Microsoft Academic Search

An extensive malacological survey was carried out between 2005-2009 in order to clarify the exact number of lymnaeid species which may be intermediate hosts of Fasciola hepatica in Venezuela. Four species were discovered during this survey, including two local species: Lymnaea cubensis and Lymnaea cousini and two exotic species: Lymnaea truncatula and Lymnaea columella. The most common local species was

JP Pointier; O Noya; B Alarcón de Noya; A Théron

2009-01-01

131

Comparison of the petroleum systems of East Venezuela in their tectonostratigraphic context  

Microsoft Academic Search

The Maturin and Guarico subbasins of East Venezuela record the transition from Cretaceous passive margin to Tertiary foreland basin with local post-orogenic transtensional basins. Petroleum is reservoired in several units ranging from Albian (El Cantil Formation) to Pliocene (Las Piedras Formation) age. Source rocks are principally in the Upper Cretaceous (Querecual Formation), and Miocene (Carapita Formation) in the Maturin subbasin

N. J. Stronach; H. M. Kerr; J. Scotchmer; V. Hunter

1996-01-01

132

Military coups in the post-cold war era: Pakistan, Ecuador and Venezuela  

Microsoft Academic Search

This article compares the failed military coups in Ecuador (2000) and Venezuela (2002) with the successful 1999 military putsch in Pakistan in order to identify what factors affect coup outcomes in third-wave democracies. The unity of the armed forces in support of the Pakistani coup, and its division in the two Latin American cases, are critical in explaining the divergent

Steven Barracca

2007-01-01

133

The Uses of Conspiracy Theories for the Construction of a Political Religion in Venezuela  

Microsoft Academic Search

This article analyses conspiracy theories as part of the wider discourses of missionary politics. It presents a case study of Venezuela and describes how its leaders use conspiracy theories as political tools. Through quotes taken form Venezuelan president Chavez's public speeches and other sources, and through a short analysis of the ideological basis of his discourses, it shows how conspiracy

Hugo Antonio; Pérez Hernáiz

2008-01-01

134

Characterization of hepatitis D virus genotype III among Yucpa Indians in Venezuela  

Microsoft Academic Search

The complete genome sequences of hepatitis D virus (HDV) strains isolated from three Yucpa Amerindians in Venezuela were determined and found to be genotype III. Comparison of these three genotype III sequences demonstrated the presence of a hypervariable region containing numerous substitutions, insertions\\/deletions and a highly conserved region containing the self-cleavage do- mains, which have been reported previously for genotypes

Tatsunori Nakano; Craig N. Shapiro; Stephan C. Hadler; John L. Casey; Masashi Mizokami; Etsuro Orito; Betty H. Robertson

2001-01-01

135

Lobomycosis in Man and Lobomycosis-like Disease in Bottlenose Dolphin, Venezuela  

PubMed Central

We report 1 case of lobomycosis caused by Lacazia loboi in a fisherman and 1 case of lobomycosis-like disease in a bottlenose dolphin (Tursiops truncatus) along the coast of Venezuela. These findings suggest that the marine environment is a likely habitat for L. loboi and a reservoir for infection.

Bermudez, Luis; Van Bressem, Marie-Francoise; Reyes-Jaimes, Oscar; Sayegh, Alejandro J.

2009-01-01

136

Universities, public policy and economic development in Latin America: the cases of Mexico and Venezuela  

Microsoft Academic Search

Since the establishment of national university systems in Mexico and Venezuela, three principal demands have dominated the formulation of university policy: the ideological demand imposed by government rhetoric and national aspirations (a demand reflected in federal expenditure), the demand of the national economy for different areas and levels of professional expertise, and the broad-based political and social demand for upward

David E. Lorey

1992-01-01

137

Pyrolysis kinetics applied to prediction of oil generation in the Maracaibo Basin, Venezuela  

Microsoft Academic Search

We use chemical kinetic parameters for oil generation derived from modified Rock-Eval and Pyromat instruments, coupled with thermal history models, to predict the timing and extent of oil generation in the Maracaibo Basin of Venezuela. The vitrinite reflectance model developed at Lawrence Livermore National Laboratory is used to calibrate thermal history models with measured vitrinite reflectance profiles. We examine the

J. J. Sweeney; S. Talukdar; A. K. Burnham; C. Vallejos; TX The Woodlands

1989-01-01

138

Comparison of fish assemblages in two littoral habitats in a Neotropical morichal stream in Venezuela  

Microsoft Academic Search

Morichales are lowland streams in South American savannas with riparian forest dominated by the moriche palm (Mauritia flexuosa ). We sampled littoral habitats from ten flooded vegetated patches (dominated by Mauritiella aculeate) and six sand banks in two months of the dry season (Feb-Mar 2005) in a stream in the savannas of Apure State, Venezuela. We collected samples that compromised

Carmen G. Montaña; Craig A. Layman; Donald C. Taphorn

2008-01-01

139

Actividad microbiana en suelos de sabanas de los Llanos Orientales de Venezuela convertidas en pasturas  

Microsoft Academic Search

Micr obial activity in Eastern Venezuelan savannas turned into grasslands. We studied the effects of season and management practices on chemical properties and biochemical parameters in a typical Ultisol soil of native and introduced pastures of the Eastern savannas of Venezuela. Sseason, soil management, and their interaction, significantly affected chemical properties and biochemical parameters. The total carbon and the water

Y. Gómez; J. Paolini

2006-01-01

140

Subsidence related horizontal earth movements in the Tia Juana field, State of Zulia, Venezuela  

Microsoft Academic Search

Subsidence due to oil exploitation in the Bolivar Coast fields in western Venezuela has been monitored since 1926. Related horizontal earth movements have been measured by geodetic methods during the last 10 yr in the northern Tia Juana field area in and around the Ule tank farm and the GLP gas liquefaction plant. Damage to storage tanks and increasing appearance

W. F. Scherer; M. A. Pedroza

1990-01-01

141

Use of the Global Positioning System (GPS) for Ground Subsidence Measurements in Western Venezuela Oil Fields  

Microsoft Academic Search

Oil production along the east coast of Lake Maracaibo in Western Venezuela produces ground subsidence which affects an area of about 1000 km2 in die form of three subsidence basins. Since 1929 the accumulative subsidence has reached 5 m with the present rate of subsidence reaching 0.2 m per year in some locations. A levelling network consisting of over 1600

A. CHRZANOWSKI; Y. Q. CHEN; T. POPLAWSKI

1991-01-01

142

Chemical kinetic model of hydrocarbon generation, expulsion, and destruction applied to the Maracaibo basin, Venezuela  

Microsoft Academic Search

This paper describes the development and application of a compositional chemical model of hydrocarbon generation, expulsion,a nd destruction for the Cretaceous La Luna Formation source rock of the Maraciabo basin, Venezuela. Applications include both laboratory and geological settings. Laboratory pyrolysis experiments were used to study bulk oil generation, expulsion, and associated changes in composition of the kerogen, extractable organic matter,

J. J. Sweeney; R. L. Braun; A. K. Burnham

1995-01-01

143

Five Years of Cyclotron Radioisotope Production Experiences at the First PET-CT in Venezuela  

NASA Astrophysics Data System (ADS)

Five years operation of a compact cyclotron installed at PET-CT facility in Caracas, Venezuela is given. Production rate of 18F labeled FDG, operation and radiation monitoring experience are included. We conclude that 18FDG CT-PET is the most effective technique for patient diagnosis.

Colmenter, L.; Sajo-Bohus, L.; Liendo, J. A.; Greaves, E. D.; Coelho, D.; Barros, H.; Castillo, J.; Esteves, L. M.; Ruiz, N.; Morales, L.; Lugo, I.

2007-10-01

144

Development of Caribbean plate tectonics: A contribution from oil exploration in Venezuela  

Microsoft Academic Search

Following several huge oil and gas discoveries during the mid-1980s in the Northern Venezuela overthrust belt more detailed geological and geophysical studies have increased their perception of structural control on sedimentary basin development. Significant improvements in seismic data quality and seismic lines positioned close to outcrops of the frontal thrust give evidence of Miocene to Pleistocene thin-skinned tectonics as the

J. Fuentes; S. Oum; R. Lander

1990-01-01

145

THE MARKET FOR BROILERS THROUGH FAST-FOOD OUTLETS IN VENEZUELA  

Microsoft Academic Search

PROAGRO is the leading firm in the broiler business in Venezuela. It is integrated through hatchery, grow-out, processing and distribution activities. As a consequence of strict price regulation policies enforced by the government in the poultry products, PROAGRO experienced serious injury to its profitability over the last few years. The most severe regulations were applied to PROAGRO's chief product (whole,

Jose E. Gomez

1978-01-01

146

Technical Assistance for Improvements and Privatization of the Water and Sanitation System of Isla Margarita, Venezuela. Final Report. Volume 1.  

National Technical Information Service (NTIS)

This report, funded by the Trade Development Agency, was conducted by Envirosoft-Engineering and Science, Inc. It details the technical assistance given for improvements and privatization of the water and sanitation systems of Isla Margaita, Venezuela. Th...

1998-01-01

147

Book Review: "Educational Reform and Administrative Development: The Cases of Columbia and Venezuela," by E. Mark Hanson.  

ERIC Educational Resources Information Center

|Reviews "Educational Reform and Administrative Development: The Cases of Colombia and Venezuela," by E. Mark Hanson, which relates the policy-making and administrative structures of these two countries to their political, historical, and cultural contexts. (TE)|

Lynch, Patrick D.

1988-01-01

148

Household energy use in urban Venezuela: Implications from surveys in Maracaibo, Valencia, Merida, and Barcelona-Puerto La Cruz  

SciTech Connect

This report identifies the most important results of a comparative analysis of household commercial energy use in Venezuelan urban cities. The use of modern fuels is widespread among all cities. Cooking consumes the largest share of urban household energy use. The survey documents no use of biomass and a negligible use of kerosene for cooking. LPG, natural gas, and kerosene are the main fuels available. LPG is the fuel choice of low-income households in all cities except Maracaibo, where 40% of all households use natural gas. Electricity consumption in Venezuela`s urban households is remarkably high compared with the levels used in households in comparable Latin American countries and in households of industrialized nations which confront harsher climatic conditions and, therefore, use electricity for water and space heating. The penetration of appliances in Venezuela`s urban households is very high. The appliances available on the market are inefficient, and there are inefficient patterns of energy use among the population. Climate conditions and the urban built form all play important roles in determining the high level of energy consumption in Venezuelan urban households. It is important to acknowledge the opportunities for introducing energy efficiency and conservation in Venezuela`s residential sector, particularly given current economic and financial constraints, which may hamper the future provision of energy services.

Figueroa, M.J.; Sathaye, J.

1993-08-01

149

Interpretacion: The Lived Experience of Interpretation in the Bilingual Psychotherapist  

ERIC Educational Resources Information Center

To enhance the effectiveness of therapy for Spanish-speaking individuals and families requires an understanding of the subtleties of language use and interpretive processing. The purpose of this phenomenological study was to describe the interpretive process in bilingual psychotherapists as they reflected upon their lived experiences of providing…

Melchor, Rosemary Laura

2008-01-01

150

Interpretacion: The Lived Experience of Interpretation in the Bilingual Psychotherapist  

ERIC Educational Resources Information Center

|To enhance the effectiveness of therapy for Spanish-speaking individuals and families requires an understanding of the subtleties of language use and interpretive processing. The purpose of this phenomenological study was to describe the interpretive process in bilingual psychotherapists as they reflected upon their lived experiences of providing…

Melchor, Rosemary Laura

2008-01-01

151

Barrio Adentro and the reduction of health inequalities in Venezuela: an appraisal of the first years.  

PubMed

This article presents an update on the characteristics and performance of Venezuela's Bolivarian health care system, Barrio Adentro (Inside the Neighborhood). During its first five years of existence, Barrio Adentro has improved access and utilization of health services by reaching approximately 17 million impoverished and middle-class citizens all over Venezuela. This was achieved in approximately two years and provides an example of an immense "South-South" cooperation and participatory democracy in health care. Popular participation was achieved with the Comités de Salud (health committees) and more recently with the Consejos Comunales (community councils), while mostly Cuban physicians provided medical care. Examination of a few epidemiological indicators for the years 2004 and 2005 of Barrio Adentro reveals the positive impact of this health care program, in particular its primary care component, Barrio Adentro I. Continued political commitment and realistic evaluations are needed to sustain and improve Barrio Adentro, especially its primary care services. PMID:19326784

Armada, Francisco; Muntaner, Caries; Chung, Haejoo; Williams-Brennan, Leslie; Benach, Joan

2009-01-01

152

Review of the Berosus Leach of Venezuela (Coleoptera, Hydrophilidae, Berosini) with description of fourteen new species  

PubMed Central

Abstract The species of the water scavenger beetle genus Berosus Leach occurring in Venezuela are reviewed. Thirty-six species are recorded, including fifteen new species, fourteen of which are described here as new: Berosus aragua sp. n., Berosus asymmetricus sp. n., Berosus capanaparo sp. n., Berosus castaneus sp. n., Berosus corozo sp. n., Berosus ebeninus sp. n., Berosus garciai sp. n., Berosus humeralis sp. n., Berosus jolyi sp. n., Berosus llanensis sp. n., Berosus megaphallus sp. n., Berosus ornaticollis sp. n., Berosus repertus sp. n., and Berosus tramidrum sp. n. The fifteenth new species, known from a single female, is left undescribed pending the collection of males. Twelve species are recorded from Venezuela for the first time: Berosus ambogynus Mouchamps, Berosus consobrinus Knisch, Berosus elegans Knisch, Berosus geayi d’Orchymont, Berosus ghanicus d’Orchymont, Berosus guyanensis Queney, Berosus holdhausi Knisch, Berosus marquardti Knisch, Berosus olivae Queney, Berosus reticulatus Knisch, Berosus wintersteineri Knisch, and Berosus zimmermanni Knisch.

Oliva, Adriana; Short, Andrew E. Z.

2012-01-01

153

Bioclastic carbonates of Margarita Island, Venezuela, as a key to exploration  

Microsoft Academic Search

Reef-derived bioclastic carbonates interlayered with autochthonous deep marine shales are known from the Eocene section of\\u000a Margarita Island in northeastern Venezuela. They consist mainly of turbidity-current deposited graded biocalcirudites, biocalcarenites,\\u000a and biocalcisiltites that usually show the Bouma sequence. They alternate with pelagic shales containingglobigerina and radiolaria. There are also very common intercalations of reworked and sorted, thinly bedded biocalcilutite and

G. Nicolas; J. Munoz

1986-01-01

154

New particle formation events observed at a high altitude site Pico Espejo, Venezuela  

NASA Astrophysics Data System (ADS)

Formation and growth events of nucleation mode particles (10-25 nm in diameter) were analyzed from 27 month period of particle size distribution measurements at the high altitude site Pico Espejo in Venezuela. Particle formation was observed both in air masses connected to boundary layer air and in free tropospheric conditions. The frequency and magnitude of particle formation at this high altitude site was comparable to many observations at lower altitude sites.

Nieminen, Tuomo; Kontkanen, Jenni; Krejci, Radovan; Ström, Johan; Tunved, Peter; Hamburger, Thomas; Calderon, Silvia; Hoffman, Pedro

2013-05-01

155

The Cuba-Venezuela Alliance: “Emancipatory Neo-Bolivarismo” Or Totalitarian Expansion?  

Microsoft Academic Search

This study examines the background as well as the ideological foundations underpinning the Cuba-Venezuela alliance. Castro and Chavez are now trying to consolidate a new political axis in Latin America, funded by Chavez’ oil diplomacy. Similarities with the Cuban experiment are highlighted, as well as Castro’s collaboration with the leadership of the Movimiento Revolucionario Bolivariano-MBR 200. The various dimensions of

Hernán Yánez

2005-01-01

156

Rapidly growing mycobacterial infection following liposuction and liposculpture--Caracas, Venezuela, 1996-1998.  

PubMed

During October 1996-March 1998, nine patients in eight hospitals in Caracas, Venezuela, acquired surgical-site infections (SSI) caused by rapidly growing mycobacteria (RGM). All episodes of RGM infection occurred within 2 months after liposuction or liposculpture (aesthetic surgical procedures). This report describes the findings of an epidemiologic investigation of this cluster by the Venezuelan Ministry of Health and underscores the importance of sterilizing surgical equipment to prevent nosocomial infections. PMID:9879630

1998-12-18

157

Applications of Planktonic foraminifera in the Paleogene of the Eastern Venezuela-Trinidad Basin  

SciTech Connect

Following increased interest in the petroleum potential of the Eastern Venezuela-Trinidad Basin, a revision of the planktonic foraminifera from the Paleogene was undertaken. The application of evolutionary trends in microperforate, medioperforate and macroperforate lineages for petroleum exploration is assessed. Scanning Electron Microscope illustrations are presented for over 100 taxa currently applied in high resolution biostratigraphy, sequence stratigraphy and paleoceanography of the region. These will allow more rapid and reliable recognition of zones, hiatuses and sequence boundaries.

Radford, S. [Department of Geology, Imperial College of Science, Technology and Medicine, London (United Kingdom)

1996-08-01

158

Chronology of mercury enrichment factors in reef corals from western Venezuela  

Microsoft Academic Search

Mining and deforestation in the early 20th century, the development of petrochemical industries during the 1950s, and the constant weathering of natural deposits of cinabrium (HgS) have made Golfo Triste, Venezuela, a region impacted by mercury (Hg). We studied the chronology of Hg in coral skeletons of Siderastrea siderea (1 colony, 1900–1996) and Montastraea faveolata (2 colonies, 1930–1999) from Parque

Ruth Ramos; Roberto Cipriani; Hector M. Guzman; Elia García

2009-01-01

159

Resistance to U.S. Economic Hegemony in Latin America: Hugo Chávez and Venezuela  

Microsoft Academic Search

Recent years have seen increasing opposition to U.S. political and economic influence in Latin America. Venezuela is a key player in the South American economy. This project researches the country’s history from the 1950s to the present and the role of the U.S. in its formation. Through political economy, this study asks if recent political changes are due to the

Rachel M. Jacques

2005-01-01

160

Receiver function study of the crustal structure of the southeastern Caribbean plate boundary and Venezuela  

Microsoft Academic Search

We have investigated crustal thickness and composition across the southeastern Caribbean plate boundary with the receiver function technique. We used teleseismic data recorded by a temporary broadband array deployed under the BOLIVAR project and the permanent national seismic network of Venezuela. We used the primary P-to-S conversion and crustal reverberations to estimate crustal thickness and average crustal VP\\/VS ratio over

Fenglin Niu; Tammy Bravo; Gary Pavlis; Frank Vernon; Herbert Rendon; Maximiliano Bezada; Alan Levander

2007-01-01

161

Rainwater chemestry at the western savannah region of the Lake Maracaibo Basin, Venezuela  

Microsoft Academic Search

The major part of Venezuela oil production is located in and around the Lake Maracaibo Basin. The samples were collected over a 1-year period at Catatumbo and La Esperanza sites. The rainwater was acidic, with a VWA-pH of 4.6 for Catatumbo and 4.2 for La Esperanza. This acidity is made up in 93% by inorganic acids (mainly H2SO4), and NH4+

J. A. Morales; C. Bifano; A. Escalona

1995-01-01

162

Hydrocarbon Magnetic Authigenesis Mechanisms in Well and Soil Samples: Review of Studies in Venezuela  

NASA Astrophysics Data System (ADS)

In recent studies we have tried to establish the correlation between shallow micromagnetic anomalies from oil wells and soil samples, with the underlying reservoir. We have combined rock magnetic experiments with Electronic Paramagnetic Resonance (EPR) studies. Logs of Magnetic Susceptibility (MS), Extractable Organic Matter Concentration (EOMC) and Organic Matter Free Radical Concentration (OMFRC) have been compared. Additionally, rock magnetic and EPR experiments were carried out to identify the magnetic phases responsible for these anomalies. In wells from oil fields located in western Venezuela, MS and EOMC anomalies coincide at the same depth levels, and OMFRC anomalies lie close to them. These anomalies are associated to framboids of authigenic magnetite. In samples from eastern Venezuela oil fields, MS anomalies seem to be caused mainly by the presence of Fe sulphides (i.e. greigite). EOMC peaks do not coincide at the same depth levels of their MS counterparts. These results lead us to the conclusion that two different authigenic processes could operate. In western Venezuela, secondary magnetic minerals could be produced by the achievement of proper themochemical conditions, reached at shallow depth levels, combined with the presence of organic matter. The hydrocarbon gas leakage alters the organic matter, and a net electron transfer from this degraded matter to Fe(III) should occur, precipitating Fe(II) magnetic minerals (e.g. magnetite). Results from soil samples at a nearby prospective area suggest a similar process. In this case the alteration of organic matter has been observed via remote sensors. On the other hand, in eastern Venezuela oil fields, high concentrations of H2S at shallow depth levels, might allow the formation of secondary Fe-sulphides without the presence of organic matter. Different results for these two areas could be linked to their inherent distinct structural complexities and chemical properties of their hydrocarbons.

Aldana, M.; Diaz, M.; Costanzo, V.

2008-05-01

163

Mercury Pollution from Artisanal Gold Mining in Block B, El Callao, Bolivar State, Venezuela  

Microsoft Academic Search

The technical and health aspects of the gold mining activity conducted by artisanal and small-scale miners in the Block B, El Callao, Bolívar State, Venezuela, were evaluated. The area, with 1731 inhabitants, is a legal mining concession of CVG-Minerven rented to small-scale mining individuals\\/companies. Miners extract the ore from 30-80 m deep shafts using explosives and transport it in small

Marcello M. Veiga; Dario Bermudez; Heloisa Pacheco-Ferreira; Luiz Pedroso; Aaron Gunson; Gilberto Berrios; Ligia Vos; Pablo Huidobro; Monika Roeser

164

Evolution of Dengue Virus Type 3 Genotype III in Venezuela: Diversification, Rates and Population Dynamics  

PubMed Central

Background Dengue virus (DENV) is a member of the genus Flavivirus of the family Flaviviridae. DENV are comprised of four distinct serotypes (DENV-1 through DENV-4) and each serotype can be divided in different genotypes. Currently, there is a dramatic emergence of DENV-3 genotype III in Latin America. Nevertheless, we still have an incomplete understanding of the evolutionary forces underlying the evolution of this genotype in this region of the world. In order to gain insight into the degree of genetic variability, rates and patterns of evolution of this genotype in Venezuela and the South American region, phylogenetic analysis, based on a large number (n = 119) of envelope gene sequences from DENV-3 genotype III strains isolated in Venezuela from 2001 to 2008, were performed. Results Phylogenetic analysis revealed an in situ evolution of DENV-3 genotype III following its introduction in the Latin American region, where three different genetic clusters (A to C) can be observed among the DENV-3 genotype III strains circulating in this region. Bayesian coalescent inference analyses revealed an evolutionary rate of 8.48 × 10-4 substitutions/site/year (s/s/y) for strains of cluster A, composed entirely of strains isolated in Venezuela. Amino acid substitution at position 329 of domain III of the E protein (A?V) was found in almost all E proteins from Cluster A strains. Conclusions A significant evolutionary change between DENV-3 genotype III strains that circulated in the initial years of the introduction in the continent and strains isolated in the Latin American region in recent years was observed. The presence of DENV-3 genotype III strains belonging to different clusters was observed in Venezuela, revealing several introduction events into this country. The evolutionary rate found for Cluster A strains circulating in Venezuela is similar to the others previously established for this genotype in other regions of the world. This suggests a lack of correlation among DENV genotype III substitution rate and ecological pattern of virus spread.

2010-01-01

165

Mycobacterium tuberculosis ecology in Venezuela: epidemiologic correlates of common spoligotypes and a large clonal cluster defined by MIRU-VNTR-24  

Microsoft Academic Search

BACKGROUND: Tuberculosis remains an endemic public health problem, but the ecology of the TB strains prevalent, and their transmission, can vary by country and by region. We sought to investigate the prevalence of Mycobacterium tuberculosis strains in different regions of Venezuela. A previous study identified the most prevalent strains in Venezuela but did not show geographical distribution nor identify clonal

Edgar Abadía; Monica Sequera; Dagmarys Ortega; María Victoria Méndez; Arnelly Escalona; Omaira Da Mata; Elix Izarra; Yeimy Rojas; Rossana Jaspe; Alifiya S Motiwala; David Alland; Jacobus de Waard; Howard E Takiff

2009-01-01

166

Microseismicity evidence for subduction of the Caribbean plate beneath the South American Plate in northwestern Venezuela  

NASA Astrophysics Data System (ADS)

Over 1100 microearthquakes with body wave magnitude mb<4 have been located in western Venezuela and the southwestern Caribbean region since the installation in 1980 of the Venezuelan Seismological Array, together with 120 events of mb?4, one of them with surface wave magnitude Ms˜6. This tectonically complex region is part of the boundary between the Caribbean and the South American plates. The main seismically active feature inland in western Venezuela is the northeast striking, 600-km long, 100-km wide, right-lateral strike-slip Boconó fault zone along the Venezuelan Andes. About 80% of the earthquakes located in the entire region in the period 1980-mid-1995 have occurred on this fault zone, at focal depths <20 km. Microearthquake activity at lower rates also occurs northwest of the Venezuelan Andes, both in the continental and Caribbean sea regions. Part of this activity takes place at depths down to ˜150 km. Northwest oriented seismicity depth profiles show the existence of a Benioff zone dipping to the southeast beneath northwestern Venezuela and northern Colombia. This indicates the presence of a northeast striking, southeast dipping subducted slab of the Caribbean plate beneath the South American plate. Hypocentral locations show that the northeastern end of this subduction occurs northwest of the Curaçao-Aruba region, in the vicinity of a northwest trending, right-lateral strike-slip fault zone that joins up with the northeastern end of the Boconó fault zone. This latter place turns out to be the western end of the east-west striking San Sebastián fault along the Venezuelan coast.

PéRez, Omar J.; Jaimes, Martha A.; Garciacaro, Emilio

1997-08-01

167

Residential energy use and conservation in Venezuela: Results and implications of a household survey in Caracas  

SciTech Connect

This document presents the final report of a study of residential energy use in Caracas, the capital of Venezuela. It contains the findings of a household energy-use survey held in Caracas in 1988 and examines options for introducing energy conservation measures in the Venezuelan residential sector. Oil exports form the backbone of the Venezuelan economy. Improving energy efficiency in Venezuela will help free domestic oil resources that can be sold to the rest of the world. Energy conservation will also contribute to a faster recovery of the economy by reducing the need for major investments in new energy facilities, allowing the Venezuelan government to direct its financial investments towards other areas of development. Local environmental benefits will constitute an important additional by-product of implementing energy-efficiency policies in Venezuela. Caracas`s residential sector shows great potential for energy conservation. The sector is characterized by high saturation levels of major appliances, inefficiency of appliances available in the market, and by careless patterns of energy use. Household energy use per capita average 6.5 GJ/per year which is higher than most cities in developing countries; most of this energy is used for cooking. Electricity accounts for 41% of all energy use, while LPG and natural gas constitute the remainder. Specific options for inducing energy conservation and energy efficiency in Caracas`s residential sector include energy-pricing policies, fuel switching, particularly from electricity to gas, improving the energy performance of new appliances and customer information. To ensure the accomplishment of an energy-efficiency strategy, a concerted effort by energy users, manufacturers, utility companies, government agencies, and research institutions will be needed.

Figueroa, M.J.; Ketoff, A.; Masera, O.

1992-10-01

168

[Cardiovascular risk: initial estimation in the study cohort "CDC of the Canary Islands in Venezuela"].  

PubMed

In Venezuela as in the Canary Islands (Spain), cardiovascular disease is a major cause of morbidity and mortality. The purpose of this research is to estimate the cardiovascular risk in the Canary Islands migrants living in Venezuela and participating in the study cohort "CDC of the Canary Islands in Venezuela". 452 individuals, aged 18 to 93 years (54.9% women), were enrolled between June 2008 and August 2009. A data survey was performed and their weight, height, abdomen and hip circumferences, and blood pressure were measured. After a 12-hour fasting period, a blood sample was obtained for glucose and lipid profile determinations. 40.5% of the subjects were over 65 years of age and 8% corresponded to the younger group (18-30 years). In men, the average age was 57.69 +/- 18.17 years and the body mass index 29.39 +/- 5.71 kg/m2, whereas women were 56.50 +/- 16.91 years and 28.20 +/- 5.57 kg/m2, respectively. The prevalence of metabolic syndrome was 49.1%, overweight and obesity together 75,2%, abdominal obesity 85.4%, diabetes 17.4%, impaired fasting glucose (IFG) 12.2%, elevated blood pressure 52.9%, low HDL-cholesterol 53,8% and elevated serum triglycerides 31%. Among subjects without diabetes or IFG, a third showed a high triglycerides/HDL-cholesterol ratio, indicating insulin resistance. We conclude that the Canarian-Venezuelan community suffers high prevalence of cardiovascular risk factors (obesity, abdominal obesity, dyslipidemia, diabetes). In relation to the current population of the Canary Islands, they show a lower frequency of IFG and a higher frequency of low HDL-cholesterol. In comparison to the Venezuelan population (Zulia), they showed to have lower prevalence of IFG, low HDL cholesterol and elevated triglycerides. PMID:22523842

Viso, Miguel; Rodríguez, Zulma; Loreto, Neydys; Fernández, Yolima; Callegari, Carlos; Nicita, Graciela; González, Julio; Cabrera de León, Antonio; Reigosa, Aldo

2011-12-01

169

(Late?) Paleozoic age for the “Cretaceous” Tucutunemo Formation, northern Venezuela: Stratigraphic and tectonic implications  

NASA Astrophysics Data System (ADS)

The largely phyllitic Tucutunemo Formation of the Caribbean Mountains of north-central Venezuela has been assigned to the Early or Late Cretaceous on the basis of lithologic correlation. Reexamination of some limestones in thin section revealed a crinoid-brachiopod microfacies in which productid spine bases and sections were identified. Other forms include bryozoans, probable dasyclad algae, and a possible chaetetid. The microfacies closely resemble those of limestones of the Permian Palmarito Formation of the Venezuelan Andes. These features suggest a (late?) Paleozoic age for the Tucutunemo Formation. A range of possible tectonic settings for the formation is summarized in two autochthonous and two allochthonous models.

Benjamini, C.; Shagam, R.; Menendez, A.

1987-10-01

170

Sentinel Surveillance of Influenza-Like Illness in Two Hospitals in Maracay, Venezuela: 2006-2010  

PubMed Central

Background Limited information exists on the epidemiology of acute febrile respiratory illnesses in tropical South American countries such as Venezuela. The objective of the present study was to examine the epidemiology of influenza-like illness (ILI) in two hospitals in Maracay, Venezuela. Methodology/Principal Findings We performed a prospective surveillance study of persons with ILI who presented for care at two hospitals in Maracay, Venezuela, from October 2006 to December 2010. A respiratory specimen and clinical information were obtained from each participant. Viral isolation and identification with immunofluorescent antibodies and molecular methods were employed to detect respiratory viruses such as adenovirus, influenza A and B, parainfluenza, and respiratory sincytial virus, among others. There were 916 participants in the study (median age: 17 years; range: 1 month – 86 years). Viruses were identified in 143 (15.6%) subjects, and one participant was found to have a co-infection with more than one virus. Influenza viruses, including pandemic H1N1 2009, were the most frequently detected pathogens, accounting for 67.4% (97/144) of the viruses detected. Adenovirus (15/144), parainfluenza virus (13/144), and respiratory syncytial virus (11/144) were also important causes of ILI in this study. Pandemic H1N1 2009 virus became the most commonly isolated influenza virus during its initial appearance in 2009. Two waves of the pandemic were observed: the first which peaked in August 2009 and the second - higher than the preceding - that peaked in October 2009. In 2010, influenza A/H3N2 re-emerged as the most predominant respiratory virus detected. Conclusions/Significance Influenza viruses were the most commonly detected viral organisms among patients with acute febrile respiratory illnesses presenting at two hospitals in Maracay, Venezuela. Pandemic H1N1 2009 influenza virus did not completely replace other circulating influenza viruses during its initial appearance in 2009. Seasonal influenza A/H3N2 was the most common influenza virus in the post-pandemic phase.

Comach, Guillermo; Teneza-Mora, Nimfa; Kochel, Tadeusz J.; Espino, Carlos; Sierra, Gloria; Camacho, Daria E.; Laguna-Torres, V. Alberto; Garcia, Josefina; Chauca, Gloria; Gamero, Maria E.; Sovero, Merly; Bordones, Slave; Villalobos, Iris; Melchor, Angel; Halsey, Eric S.

2012-01-01

171

[New additions to the marine algae of Mochima National Park, Sucre, Venezuela].  

PubMed

The marine algal flora from the eastern coast of Mochima National Park, Sucre, Venezuela was studied with a total of 51 taxa identified, including eight new additions of red algae which are Erythrotrichia carnea (Dillwyn) J. Agardh, Sahlingia subintegra (Rosenvinge) Kornmann, Liagora ceranoides Lamouroux, Asparagopsis taxiformis (Delile) Trevisan, Dasya corymbifera J. Agardh, Chondria dasyphylla (Woodward) C. Agardh, Herposiphonia secunda f. tenella (C. Agardh) M.J. Wynne and Polysiphonia subtilissima Montagne. Morphological and anatomical aspects of the specimens are described and illustrated. PMID:15264567

Silva, Soraida; Brito, Leonor; Lemus, Andrés

2003-06-01

172

Importancia de las plantas medicinales en el autocuidado de la salud en tres caseríos de Santa Ana Trujillo, Venezuela. The importance of medicinal plants in health care in three small villages of the Santa Ana county at Trujillo state, Venezuela  

Microsoft Academic Search

In order to gather some information about the importance of medicinal plants in the primary health care, the use of plants in three small villages of the Santa Ana county, Pampán municipality at Trujillo State, Venezuela, was quantitatively analyzed. To do this, a local epidemiology diagnosis was carried out and the etnopharmacological information obtained was recorded using the TRAMIL survey.

TEOLINDA CARRILLO-ROSARIO Y GLENDA

173

[Molecular and serological diagnosis of a dengue outbreak in Coro, Falcón state, Venezuela].  

PubMed

Dengue virus (DV) is responsible for a spectrum of diseases, from a self-limited fever disease (DF, dengue fever) to the more severe forms of hemorrhagic fever/dengue shock syndrome (DHF/DSS). The aim of this study was the serological and molecular confirmation of an outbreak of dengue in Falcon state, Venezuela. A total of 54 sera from patients with clinical diagnosis of DV infection were analyzed by an enzyme immunoassays developed in Venezuela (ELISA -IgM e -IgG) and by PCR. From them, 78% exhibited DV infection (PCR+ y/o IgM+), 48% exhibited viremia by PCR and 57% were positive to IgM. An interesting observation was the high percent (76%) of patients with past or secondary infection (IgG positive), which included all the patients exhibiting clinical symptoms of DHF (n = 8). From the PCR positive sera, serotype 1 was found in 27%, serotype 2 in 54% and serotype 4 in 19%. No serotype 3 was found circulating in this population, although this serotype was already circulating in the nearby island of Aruba. The combination of serological and molecular methods allow us to obtain a fairly precise information of this outbreak. PMID:14552060

Moros, Zoila Caridad; Abad, María Jesús; Arsenak, Miriam; Martínez, Dilia; Cierco, Maria Magdalena; Costagliola, Asunta; Urbina, Leyda; Taylor, Peter; Liprandi, Ferdinando; Pujol, Flor Helene

2003-09-01

174

Comparison of the petroleum systems of East Venezuela in their tectonostratigraphic context  

SciTech Connect

The Maturin and Guarico subbasins of East Venezuela record the transition from Cretaceous passive margin to Tertiary foreland basin with local post-orogenic transtensional basins. Petroleum is reservoired in several units ranging from Albian (El Cantil Formation) to Pliocene (Las Piedras Formation) age. Source rocks are principally in the Upper Cretaceous (Querecual Formation), and Miocene (Carapita Formation) in the Maturin subbasin and in the Upper Cretaceous (Tigre Formation) and Oligocene (Roblecito and La Pascua Formations) in the Guarico subbasin. An extensive well database has been used to address the distribution and provenance of hydrocarbons in the context of a tectonostratigraphic model for the evolution of the East Venezuela basin. Nine major plays have been described, comprising thirteen petroleum systems. The principal factors influencing the components of individual petroleum systems are as follows: (1) structural controls on Upper Cretaceous source rock distribution, relating to block faulting on the proto-Caribbean passive margin; (2) paleoenvironmental controls on source rock development within the Oligocene-Miocene foreland basin; and (3) timing of subsidence and maturation within the Oligocene-Upper Miocene foreland basin and the configuration of the associated fold and thrust belt, influencing long range and local migration routes (4) local development of Pliocene post-orogenic transtensional basins, influencing hydrocarbon generation, migration and remigration north of the Pirital High.

Stronach, N.J.; Kerr, H.M.; Scotchmer, J. [Robertson Research International Ltd., Llandudno, Gwynedd (United Kingdom); Hunter, V. [Consultores Geostrat CA, Puerto La Cruz (Venezuela)

1996-08-01

175

Two new Fusicoccum species from Acacia and Eucalyptus in Venezuela, based on morphology and DNA sequence data  

Microsoft Academic Search

Botryosphaeria spp. are common endophytes of woody plants, and they also include some serious pathogens of Eucalyptus and Acacia species. Numerous anamorphs have been associated with Botryosphaeria, of which the species Fusicoccum are amongst the most common. Here, we characterize two new Fusicoccum species, isolated from Eucalyptus and Acacia trees in Venezuela, based on morphological features in culture and comparisons

Sari Mohali; Bernard Slippers; Michael J. Wingfield

2006-01-01

176

Voice, Video and Data Transmission over Electrical Power Supply Networks. PLC (Power Line Communications): A Last Mile Alternative for Venezuela  

Microsoft Academic Search

In general terms, the public telecommunication networks in Venezuela are conformed by access, transport and core networks. The locations where does not exist telecommunications services but there are users, generally there exist electrical service, which allows the utilization of the electrical systems as the access network. During the development of this research we consulted documentation related to PLC implementations in

Luis R. Madera

2006-01-01

177

The significance of episodic rains for reproductive phenology and productivity of trees in semiarid regions of northwestern Venezuela  

Microsoft Academic Search

The semiarid regions of northwestern Venezuela have extremely low and highly unpredictable precipitation, yet these conditions support species with contrasting phenology and leaf longevity. Episodic rains significantly increased leaf water potential (from -5 to -2.5 MPa) in several species and, in some cases, triggered flowering, leading us to hypothesize that the coexistence of species with contrasting phenology is due to differences

Míriam Díaz; Eréndira Granadillo

2005-01-01

178

ALGUNOS ATRIBUTOS DE LA ESTRUCTURA COMUNITARIA DE LA ICTIOFAUNA DE LA LAGUNA GRANDE DE OBISPO, GOLFO DE CARIACO, VENEZUELA  

Microsoft Academic Search

Species composition, relative abundance, diversity and community structure of fishes were studied from monthly sampling during December 1995 to November1996 in the Laguna Grande de Obispo, Gulf of Cariaco, Sucre State, Venezuela. Sampling were realised in 3 stations inside the lagoon with a small beach seine and the other 4 stations with a large beach seine. Seventy four species belonging

Andrés Adolfo De Grado; Abul Bashirullah

179

Public relations and strategic issues management challenges in Venezuela: A discourse analysis of Crystallex International Corporation in Las Cristinas  

Microsoft Academic Search

This investigation, using critical discourse analysis (CDA), seeks to develop an understanding of strategic issues management through Crystallex International Corporation’s discursive construction and management of legitimacy in the Las Cristinas mine in Venezuela. This analysis of the Las Cristinas case unearths elements that could provide useful insights about the Latin American environment in general and public relations efforts in that

Karina Peñaloza de Brooks; Damion Waymer

2009-01-01

180

EVIDENCES FOR THE PRESENCE OF A NEW PETROLEUM SYSTEM IN EASTERN-VENEZUELA: PERSPECTIVES FOR FUTURE EXPLORATION  

Microsoft Academic Search

For crude oils (from the South-Central part of the Eastern Venezuela Basin, EVB) three oil seeps (two of them located in The Paría Península region, and the other one towards the north-western side of the Orinoco river) and three reservoir rocks with oil impregnations (Junin Field, Orinoco Heavy Oil Belt) from the EVB, were analysed in this study in order

Carolina C. OLIVARES

181

Molecular epidemiology of dengue type 2 virus in Venezuela: evidence for in situ virus evolution and recombination  

Microsoft Academic Search

Epidemic outbreaks of dengue fever (DF) were first recorded in Venezuela in 1978 and were followed by the emergence of dengue haemorrhagic fever (DHF) outbreaks in 1989. To gain a better understanding of the nature of these epidemics, the complete envelope (E) gene sequence of 34 Venezuelan dengue type 2 (DEN-2) viruses, isolated between 1997 and 2000 was determined. Of

N. Y. Uzcategui; D. Camacho; G. Comach; R. Cuello de Uzcategui; E. C. Holmes; E. A. Gould

2001-01-01

182

Population, Land Use and Deforestation in the Pan Amazon Basin: a Comparison of Brazil, Bolivia, Colombia, Ecuador, Perú and Venezuela  

Microsoft Academic Search

This paper discusses the linkages between population change, land use, and deforestation in the Amazon regions of Brazil, Bolivia, Colombia, Ecuador, Perú, and Venezuela. We begin with a brief discussion of theories of population–environment linkages, and then focus on the case of deforestation in the PanAmazon. The core of the paper reviews available data on deforestation, population growth, migration and

Stephen G. Perz; Carlos Aramburú; Jason Bremner

2005-01-01

183

FLUJOS DE COMERCIO INTRAINDUSTRIAL DE LAS EXPORTACIONES REPRESENTATIVAS ENTRE VALLE DEL CAUCA, ECUADOR Y VENEZUELA 1980 – 2006  

Microsoft Academic Search

En el presente trabajo se analiza el comportamiento del comercio intraindustrial (CII) de los subsectores representativos de la industria del Valle del Cauca con los países de Ecuador y Venezuela para el período 1980-2006 a través del índice Greenaway y Milner y el índice de Brülhart. De esta forma se corrige el problema de agregación presentado en mediciones anteriores y

Aura María Muñoz Cardona; Lina Johanna Salinas Luna

2009-01-01

184

Mantle Structure at Tectonic Corners: an Investigation of Venezuela and SE Alaska Using Shear-wave Splitting Measurements  

NASA Astrophysics Data System (ADS)

We are in the process of making shear-wave splitting measurements to look at mantle structure in two tectonic corners: Venezuela and southeast Alaska. Both sites are in the area of recent temporary, broadband, seismic experiments. The Venezuela data came from the recently completed BOLIVAR experiment. BOLIVAR (Broadband Ocean and Land Investigations of Venezuela and the Antilles arc Region) consists of 27 PASSCAL sites, 33 FUNVISIS (Venezuelan National Network) sites, 12 broadband OBS instruments and 8 broadband stations run by Rice University. The Alaska data comes from an ongoing experiment called STEEP (SainT Elias Erosion/tectonics Project). STEEP consists of 22 broadband seismic sites in addition to available data from 6 existing broadband sites in the same area. Preliminary Bolivar experiment results show northern Venezuelan stations with fast axes oriented approximately parallel to the relative Caribbean-South American plate motion. This is consistent with previous studies. Stations in western Venezuela show northeast oriented fast axes consistent with relative motion of the Maracaibo Block. Stations to the south in the Orinoco Basin show strong spatial variations that suggest the influence of a three-dimensional flow pattern in the upper mantle of this region or unresolved data problems resulting from this deep sedimentary basin.

Growdon, M. A.; Pavlis, G. L.; Niu, F.

2006-12-01

185

Biogenic Forsterite and Opal as a Product of Biodeterioration and Lichen Stromatolite Formation in Table Mountain Systems (Tepuis) of Venezuela  

Microsoft Academic Search

Biogenic physical weathering and leaching of the quartzite dominated table mountain systems of South America is a slow but strongly biologically influenced process. Observations and analyses on the basis of sample materials collected during an expedition to the protected areas of the most conspicuous tepuis of Venezuela are reported. The rock material consists of more than 98% silica, and the

2001-01-01

186

Potential of vetiver (Vetiveria zizanioides (L.) Nash) for phytoremediation of petroleum hydrocarbon-contaminated soils in Venezuela  

Microsoft Academic Search

Venezuela is one of the largest oil producers in the world. For the rehabilitation of oil-contaminated sites, phytoremediation represents a promising technology whereby plants are used to enhance biodegradation processes in soil. A greenhouse study was conducted to determine the tolerance of vetiver (Vetiveria zizanioides (L.) Nash) to a Venezuelan heavy crude oil in soil. Additionally, the plant's potential for

Regine Brandt; Nicole Merkl; Rainer Schultze-Kraft; Carmen Infante; Gabriele Broll

2006-01-01

187

Palm worm: (Rhynchophorus palmarum) traditional food in Amazonas, Venezuela—nutritional composition, small scale production and tourist palatability  

Microsoft Academic Search

We describe the use of alerito, the larva of the Rhynchophorus palmarum (Coleoptera: Curculionidae), by the Jivi (Guajibo) community of Alcabala de Guajibo, Amazonas, Venezuela. The Indians gather the palm worms from damaged or fallen palm stems and eat them raw or roasted. We analysed the nutrient composition of the palm worm and found that it is an excellent source

H. Cerda; R. Martinez; N. Briceno; L. Pizzoferrato; P. Manzi; M. Tommaseo Ponzetta; O. Marin; M. G. Paoletti

2001-01-01

188

FENOLOGIA REPRODUCTIVA EN TRES TIPOS DE VEGETACION DE LA PLANICIE COSTERA DE LA PENINSULA DE PARAGUANA, VENEZUELA  

Microsoft Academic Search

Reproductive phenology of 51 plant species was evaluated according to life form and vegetation types in a coastal plain of the Paraguaná Peninsula, Estado Falcón, Venezuela. Plant species distribution according to three vegetation types (herbaceous littoral, herbaceous psamophil, and mangrove area) was determined. Life form frequency was different according to vegetation type. Herbaceous littoral and herbaceous psamophil vegetation were dominated

Luis José Lemus-Jiménez; Nelson Ramírez

189

Micrandra inundata (Euphorbiaceae), a New Species with Unusual Wood Anatomy from Blackwater River Banks in Southern Venezuela  

Microsoft Academic Search

Micrandra inundata is a distinctive new species adapted to seasonally flooded black-water river banks in southern Venezuela. Trees rarely exceed 10 m in height but have thick basal trunks composed of very lightweight wood. It has the smallest leaves and fruits of any known Micrandra species and appears to be most closely related to M. minor Benth. The botanical description

Paul E. Berry; Alex C. Wiedenhoeft

2004-01-01

190

Molecular characterisation of Mycobacterium tuberculosis isolates in the First National Survey of Antituberculosis Drug Resistance from Venezuela  

Microsoft Academic Search

BACKGROUND: Molecular typing of Mycobacterium tuberculosis strains has become a valuable tool in the epidemiology of tuberculosis (TB) by allowing detection of outbreaks, tracking of epidemics, identification of genotypes and transmission events among patients who would have remained undetected by conventional contact investigation. This is the first genetic biodiversity study of M. tuberculosis in Venezuela. Thus, we investigated the genetic

Liselotte Aristimuño; Raimond Armengol; Alberto Cebollada; Mercedes España; Alexis Guilarte; Carmen Lafoz; María A Lezcano; María J Revillo; Carlos Martín; Carmen Ramírez; Nalin Rastogi; Janet Rojas; Albina Vázques de Salas; Christophe Sola; Sofía Samper

2006-01-01

191

VGG2002, a new high-resolution geoid for Venezuela and Eastern Caribbean  

NASA Astrophysics Data System (ADS)

This paper describes a new high-resolution geoid for Venezuela and the East Caribbean Sea. The Venezuelan Gravimetric Geoid 2002 (VGG2002) covers the area between 0oN-20oN and 285oE-305oE with a resolution of 1'x1'. An additional 2o-zone was included to avoid boundary effects. About 1.5 million free-air gravity anomalies were used. They originate from PDVSA (Petróleos de Venezuela S.A.), BGI (Bureau Gravimetrique International) and the GEODAS data base of NGDC (National Geophysical Data Center). In marine areas, 1'x1' gravity anomalies derived from altimetry (S&Sv9.1) were also included. In order to determined the long wavelength geoid signal the EGM96 global geopotential model was used as reference. Short wavelength contributions were derived from a digital terrain model with 30'' (GTOPO30 model) and 2' (S&Sv8.2 model) resolution respectively. Using the GRAVSOFT software, the geoid undulations were computed with the remove-restore technique. The computation involves a spherical approximation to evaluate the Stokes integral by two dimensional spherical Fast Fourier Transform with 100% zero-padding. The terrain corrections were computed by Residual Terrain Model method using prism numeric integration and taking into account the topographic anomalies relative to a mean height surface of 15'x15' resolution. This surface was obtained by a moving average of the digital terrain model. In marine areas the height anomalies were completed by mean sea level deviations of POCM, an oceanographic model of the ocean dynamic topography. Subsequently, the quasi-geoid was converted to geoid heights. The accuracy was evaluated by about 300 GPS/leveling stations and absolute differences to TOPEX/Poseidon (nine years) mean sea surface profiles. These show that the absolute agreement with respect to the national vertical datum is generally better than 30 cm RMS for most parts of Venezuela, 15 cm RMS in coastal areas and 5 cm RMS at sea.

Acuña, G.; Bosch, W.

2003-04-01

192

Conditions for the production of jadomycin B by Streptomyces venezuelae ISP5230: Effects of heat shock, ethanol treatment and phage infection  

Microsoft Academic Search

Summary The novel benzoxazolophenanthridine antibiotic, jadomycin B, is produced byStreptomyces venezuelae ISP5230 following a 42 °C heat shock or exposure to ethanol. To further characterize these unusual culture conditions, studies were carried out using different media, varying nutrient concentrations, initial pH, and time of application of heat or ethanol stress. Highest titers of jadomycin B accumulated 48 h afterS. venezuelae

Janice L. Doull; Amrit K. Singh; Melanie Hoarel; Stephen W. Ayer

1994-01-01

193

New olivosyl derivatives of methymycin/pikromycin from an engineered strain of Streptomyces venezuelae.  

PubMed

A mutant strain of Streptomyces venezuelae was engineered by deletion of the entire gene cluster related to biosynthesis of the endogenous deoxysugar (TDP-D-desosamine) and replacement with genes required for biosynthesis of an intermediate sugar (TDP-4-keto-6-deoxy-D-glucose) or an exogenous sugar (TDP-D-olivose), from the oleandomycin and urdamycin deoxysugar pathways. The 'sugar-flexible' glycosyltransferase (DesVII) was able to attach the intermediate sugar and the new sugar to both 12- and 14-membered macrolactones thus producing quinovose or olivose glycosylated 10-deoxymethynolide and narbonolide, respectively. In addition, hydroxylated analogs of the new metabolites were detected. These results demonstrate a successful attempt of engineering the deoxysugar pathway for generation of novel hybrid macrolide antibiotics. PMID:15358425

Hong, Jay Sung Joong; Park, Sung Hee; Choi, Cha Yong; Sohng, Jae Kyung; Yoon, Yeo Joon

2004-09-15

194

Management of a giant deep field: El Furrial Field, Eastern Venezuela  

SciTech Connect

The Furrial Field is located in Eastern Venezuela and produces a 25 to 30{degrees} API asphaltenic crude oil from a 1500 ft thick Oligocene sand interval at a depth of 15,000 ft. The bubble point is about 4500 psi as compared to an original pressure of 11,000 psi. Oil in place is approximately 6800 million STB. Currently production is 350 MB/D from 77 well streams (Naricual Formation), and water is being injected at 400 MB/D to maintain pressure. The combination of a volumetric reservoir and asphaltenic nature of crude oil resulted in a rapid decrease in well productivity and reservoir pressure, creating the necessity to maintain reservoir pressure to maximize recovery. Discussed in this paper are the reservoir management techniques and strategies used by Lagoven to develop and operate these complex reservoirs. Acquisition and analysis of these data adequate to properly implement these management techniques are covered in detail.

Pinto, N.; Mengual, R.; Anz, J.; Rodney, C. [Lagoven, S.A., Maturin (Venezuela)

1996-08-01

195

Nutrient content of earthworms consumed by Ye'Kuana Amerindians of the Alto Orinoco of Venezuela.  

PubMed Central

For the Makiritare (Ye'Kuana) native people of the Alto Orinoco (Venezuela), earthworms (Anellida: Glossoscolecidae) are an important component of the diet. Two species in particular are widely consumed: 'kuru' (Andiorrhinus kuru n. sp.) and 'motto' (Andiorrhinus motto). We analysed eviscerated kuru body proper, and whole and smoked preparations of motto for their content of protein and amino acids, fatty acids and 20 minerals and trace elements. The samples contained large amounts of protein (64.5-72.9% of dry weight), essential amino acids, calcium and iron together with notable quantities of other important elements, indicating that these earthworms contain potentially useful quantities of many nutrients that are critical to the health of the humans who consume them.

Paoletti, M G; Buscardo, E; VanderJagt, D J; Pastuszyn, A; Pizzoferrato, L; Huang, Y-S; Chuang, L-T; Millson, M; Cerda, H; Torres, F; Glew, R H

2003-01-01

196

Genetic diversity between and within the arenavirus species indigenous to western Venezuela  

PubMed Central

The results of analyses of Z, RNA-dependent RNA polymerase, glycoprotein precursor, and nucleocapsid protein gene sequence data suggested that Guanarito virus was the most common cause of Venezuelan hemorrhagic fever in a 7-year period in the 1990’s and that the evolution of Pirital virus in association with Sigmodon alstoni (Alston’s cotton rat) has occurred at a significantly higher rate than the evolution of Guanarito virus in association with Zygodontomys brevicauda (short-tailed cane mouse) on the plains of western Venezuela. The results of analyses of the primary structures of the glycoproteins of the 8 strains of Guanarito virus isolated from humans suggested that these strains would be highly cross-reactive in neutralization assays. Thus, passive antibody therapy may prove beneficial in the treatment of human disease caused by strains of Guanarito virus that are enzootic in the region in which Venezuelan hemorrhagic fever is endemic.

Fulhorst, Charles F.; Cajimat, Maria N.B.; Milazzo, Mary Louise; Paredes, Hector; de Manzione, Nuris M. C.; Salas, Rosa A.; Rollin, Pierre E.; Ksiazek, Thomas G.

2008-01-01

197

CTX-M-14 ?-lactamase-producing Citrobacter freundii isolated in Venezuela  

PubMed Central

A clinical isolate of C. freundii with reduced susceptibility to extended-spectrum ?-lactams from a woman with cystocele associated with recurrent urinary tract infection was analyzed. Susceptibility tests, double disk synergy tests (DDST) and enzymatic activity by the agar iodometric method suggested the presence of ESBLs. Conjugation experiments revealed the presence of a large conjugative plasmid (pLM07/20) with an exclusive FrepB replicon type (IncF/FIB). PCR analysis and sequencing confirmed the presence of the blaCTX-M-14 gene in the pLM07/20 from C. freundii.LM07/10. Although this is the first report of CTX-M-14 in Venezuela, we alert the medical community that future increase of these ?-lactamases in our city could be due to dissemination of plasmids into bacterial populations.

2011-01-01

198

A revision of the Larainae (Coleoptera, Elmidae) of Venezuela, with description of nine new species  

PubMed Central

Abstract The species of the riffle beetle subfamily Larainae occurring in Venezuela are revised. Examination of 756 specimens yielded 22 species in nine genera occurring throughout the country. Seven species are newly recorded from the country: Phanoceroides sp. 1, Phanocerus clavicornis Sharp, 1882, Phanocerus congener Grouvelle, 1898, Pharceonus volcanus Spangler & Santiago-Fragoso, 1992, Disersus dasycolus Spangler & Santiago-Fragoso, 1992, Disersus chibcha Spangler & Santiago-Fragoso, 1987, and Disersus inca Spangler & Santiago-Fragoso, 1992. Nine species are found to be new to science, which are here described: Hexanchorus dentitibialis sp. n., H. falconensis sp. n., H. flintorum sp. n., H. homaeotarsoides sp. n., H. inflatus sp. n., Phanocerus rufus sp. n., Pharceonus grandis sp. n., Pharceonus ariasi sp. n., Potamophilops bostrychophallus sp. n. Additionally, a key to species, distribution maps, and photographs and genitalia illustrations are provided for all species.

Maier, Crystal A.

2013-01-01

199

The Double-Astrograph Telescope is working at the Observatorio Astronómico Nacional of Venezuela  

NASA Astrophysics Data System (ADS)

The Double Astrograph telescope (two 0.5 m lenses) in the Observatorio Astronómico Nacional of Venezuela (OAN) will soon be available for observations to the astronomical comunity. Despite of being placed at the OAN since thirty years ago, together with the three other telescopes installed there, it was not fully assembled. Recent engineering work on it, has got to mecanically balance the telescope and set control of the electric motors for the motion of this instrument. The current positioning and guided motions of the telescope allow for an observational quantification of the different aberrations of the optical system of the instrument. With this in mind, selected fields of stars have been observed with a CCD camera, that was installed at different locations on the focal plane. Here we show a summary of the technical operations and the first observational results, aimed at evaluating the potential of the Double Astrograph for future scientific investigations.

Abad, C.; Barroeta, G.; Schenner, H.; Plaza, L.; Ramírez, P.; Lacruz, E.

2009-05-01

200

A checklist of arthropods associated with rat carrion in a montane locality of northern Venezuela.  

PubMed

This is the first report of arthropods associated with carrion in Venezuela, using laboratory bred rats (Rattus norvegicus). Rat carcasses were exposed to colonization by arthropods in neighboring montane savanna and cloud forest habitats in the state of Miranda. The taxonomic composition of the arthropods varied between both ecosystems. Scarabaeidae, Silphidae, Micropezidae, Phoridae, Vespidae and one species of ant, were collected only in the cloud forest. Dermestes maculatus, Chrysomya albiceps, Termitidae and most species of ants, were found only in the savanna. Fourteen species were considered to be of primary forensic importance: D. maculatus, Oxelytrum discicolle, Calliphora sp., Cochliomyia macellaria, Compsomyiops sp., C. albiceps, Phaenicia cuprina, P. sericata, P. eximia, Fannia sp., Puliciphora sp., Megaselia scalaris, Ravina sp. and Sarcophaga sp. PMID:17386987

Velásquez, Yelitza

2007-03-26

201

Visual measurements and spectral survey of night sky brightness in Venezuela and Italy  

NASA Astrophysics Data System (ADS)

This paper reports measurements of zenith night sky brightness and a spectral survey carried out at selected places in Venezuela and Italy. These range from large cities (Caracas and Florence) and towns (Mérida and Siena), to dark sites, such as the Venezuelan Astronomical Observatory and the Alps. Measurements were carried out visually by means of a simple photometer and spectra from 4100 to 6400 Ä, were obtained by a small spectrograph. From the results obtained at the sites tested in Italy, the sky brightness increase since 1973 is given. Since in both countries there are effective regulations to fight light pollution, and more are foreseen in the near future, it is the purpose of this paper to stress the importance, and also the need, of night sky quality monitoring over time to assess the efficacy of these legal tools.

Della Prugna, F.

1999-12-01

202

TRXRF analysis of environmental lead and heavy metals to monitor pollution in Caracas, Venezuela  

NASA Astrophysics Data System (ADS)

Environmental monitoring has been one of the major issues worldwide since the Rio Conference 1992. In Venezuela several projects started to assess the industrial activity as a burden on the living environment. In this work we present a quantitative analysis of environmental samples collected in a residential and industrial sector of the Capital using the powerful technique of total reflection X-ray fluorescence. Sample preparation is described and results are shown of lead and other heavy metals. The elements with higher concentration were Fe, Sn and Pb which reported values in the range of 1.9-2.9 wt.%, 0.8-1.4 wt.% and 0.2-0.4 wt.%, respectively. Total heavy element concentration in street dust is in the range of 3-4 wt.% underscoring the need for governmental programs to implement pollution limiting measures by displacing the heavy industries away from Caracas and to implement advanced instrumental techniques to monitor the environment.

Suarez, S. M.; Sajo-Bohus, L.; Greaves, E. D.; Dominguez v, J. R.; Villar, E.

2004-01-01

203

Mantle flow beneath northwestern Venezuela: Seismic evidence for a deep origin of the Mérida Andes  

NASA Astrophysics Data System (ADS)

We measured shear wave splitting from SKS data recorded by the national seismic network of Venezuela and a linear broadband PASSCAL/Rice seismic array across the Mérida Andes. The linear array was installed in the second phase of the passive seismic component of the BOLIVAR project to better understand the complicated regional tectonics in western Venezuela. Using the method proposed by Wolfe and Silver (1998), SKS waveforms from 2 to 36 earthquakes, mostly from the Tonga subduction zone, were selected for each of the 23 stations in the region in order to do splitting analysis. The fast polarization directions can be divided into 3 zones, all in agreement with local GPS data: The first zone comprises the stations north of the dextral strike-slip Oca-Ancon fault. These stations show the largest split times (1.6-3.2 s), oriented in a roughly EW direction, and are similar to splitting observations made further to the east along the strike slip plate boundary (Growdon et al., 2009). We attribute this to trench-parallel mantle flow that passes around the northwest corner of the subducting Caribbean plate and along the northern edge of South America as proposed by Russo and Silver (1994), forming an eastward flow beneath the southern Caribbean plate. Zone two is the Mérida Andes, with the right lateral Bocono fault in the center, where split orientations are at ~ N45°E, suggesting that the observed seismic anisotropy is likely caused by lithospheric deformation parallel to the Bocono fault. Zone three is east of the Bocono fault inside the Barinas-Apure Basin, where the measured split times are smaller (~ 0.8 s) with an EW fast direction that is consistent with those observed at the Guarico Basin, Maturin Basin and the Guayana Shield in the east, and are interpreted as orientation with the motion of the continent.

Masy, Jeniffer; Niu, Fenglin; Levander, Alan; Schmitz, Michael

2011-05-01

204

Eastern Venezuela Basin's Post-Jurassic evolution as a passive transform margin basin  

SciTech Connect

Passive transform margins are segments of rifted continental margins bounded by transform faults that are active during rifting and that become inactive during drifting. Examples include the northern coast of Brazil and its matching margin along the Liberia-Nigeria coast. We propose that the northern margin of the Eastern Venezuela Basin was dominantly a passive transform margin during the Cretaceous and early Paleogene, rather than a purely passive margin. Published microplate reconstructions of the southern Caribbean show Jurassic separation of the Bahamas platform from northern South America along a northwest-trending transform fault postulated to lie just northeast of Trinidad and the Guianas. We conjecture that the [open quotes]Deflexion de Barcelona[close quotes] (a northwest-trending zone of strike slip faults along the southwestern edge of the Serrania del Interior) is controlled by a basement geofracture that is the onshore expression of Jurassic transform fault southwest of and subparallel to the southwestern Bahamas transform. Implications of this conjecture for the Eastern Venezuela Basin include: (1) absence of McKenzie-type regional crustal stretching, Mesozoic thermal anomaly, and Mesozoic thermal-tectonic subsidence; (2) abrupt rather than gradual seaward changes in crustal thickness; (3)abrupt lateral changes in thickness and facies of Mesozoic sediments, as in the Piaui-Ceara basins of northern Brazil; (4) tendency for structural styles developed during Neogene compression to include more strike-slip faults and en enchelon fold sets (because of reactivation of Mesozoic transforms) than would be expected by structural inversion of a purely passive margin.

George, R.P. Jr. (EGEP Consultores, Caracas (Venezuela)); Sams, R.H. (Sams Exploration Inc., Canyon Lake, TX (United States))

1993-02-01

205

Seismic Evidence for a Vertical Tear in the South American Lithosphere Offshore Venezuela  

NASA Astrophysics Data System (ADS)

In the southeast corner of the Caribbean plate, westward subduction of oceanic (Atlantic) South America transitions to east-west transform with continental South America, forcing the South American lithosphere to tear along its former passive margin. The most widely accepted model for lithospheric detachment, the tensile tear model, envisages oblique convergence causing northwest-dipping subduction. In this model, tensile stress on the subducting slab results in detachment orthogonal to the motion vectors. Conversely, the less commonly accepted shear tear model predicts detachment parallel to the motion vectors along a vertical plane, with shear stress focused at the edge of the propagating transform boundary. The tensile tear model requires significant crustal shortening to produce the 7 km of uplift in the coastal Serrania del Interior and 10 km of subsidence in the Maturin Basin onshore Venezuela. These features have been widely interpreted as the foreland fold and thrust belt and foreland basin of a collisional orogeny. Recent numerical modeling of the lithospheric response to shear tearing has shown, however, that much of the topography of eastern Venezuela can be generated from the propagating detachment, requiring relatively little shortening. We present five types of initially independent seismic data analyses to resolve the lithospheric tear: local seismicity locations, fault plane solutions, receiver functions, wide-angle seismic data inverted for velocity structure, and a regional, balanced cross-section constrained by petroleum industry data. These five datasets image a shear tear extending near-vertically through the entire lithosphere. Confirmation of this type of detachment has implications for diverse locations with similar plate boundary geometries, such as Tonga or the Carpathians, and improves our general understanding of vertical tectonics and associated mantle driving forces.

Clark, S. A.; Levander, A.; Niu, F.; Zelt, C. A.; Sobiesiak, M.; Magnani, M.

2007-12-01

206

New advances in molecular epizootiology of canine hematic protozoa from Venezuela, Thailand and Spain.  

PubMed

The prevalence of hematozoan infections (Hepatozoon canis and Babesia sp., particularly Babesia canis vogeli) in canids from Venezuela, Thailand and Spain was studied by amplification and sequencing of the 18S rRNA gene. H. canis infections caused simultaneously by two different isolates were confirmed by RFLP analysis in samples from all the geographic regions studied. In Venezuela, blood samples from 134 dogs were surveyed. Babesia infections were found in 2.24% of the dogs. Comparison of sequences of the 18S rRNA gene indicated that protozoan isolates were genetically identical to B. canis vogeli from Japan and Brazil. H. canis infected 44.77 per cent of the dogs. A representative sample of Venezuelan H. canis isolates (21.6% of PCR-positives) was sequenced. Many of them showed 18S rRNA gene sequences identical to H. canis Spain 2, albeit two less frequent genotypes were found in the sample studied. In Thailand, 20 dogs were analyzed. No infections caused by Babesia were diagnosed, whereas 30 per cent of the dogs were positive to hematozoan infection. Two protozoa isolates showing 99.7-100% identity to H. canis Spain 2 were found. In Spain, 250 dogs were studied. B. canis vogeli infected 0.01% of the animals. The sequence of the 18S rRNA gene in Spanish isolates of this protozoa was closely related to those previously deposited in GenBank (> 99% identity). Finally, 20 red foxes were screened for hematozoans employing semi-nested PCR and primers designed to detect Babesia/Theileria. Fifty percent of the foxes were positive to Theileria annae. In addition, it was found that the PCR assay was able as well to detect Hepatozoon infections. Thirty five percent of the foxes were infected with two different H. canis isolates showing 99.8-100% identity to Curupira 1 from Brazil. PMID:17088022

Criado-Fornelio, A; Rey-Valeiron, C; Buling, A; Barba-Carretero, J C; Jefferies, R; Irwin, P

2006-11-07

207

[Distribution and density of two holothurian species in Cubagua Island, Venezuela].  

PubMed

Holothurian populations in the Caribbean have been significantly depleted in some areas, and others are still in danger to satisfy international markets. In Venezuela, this marine resource has been illegally exploited since the early 1990s. To contribute with their management and protection, this work analyzed the distribution, abundance and population structure of two commercial holothurians Isostichopus badionotus and Holothuria mexicana in Cubagua Island shores. A total of 52 stations were studied around the island during the year 2008. Surveys included visits to each station, for which a band transect of 50 m2 with four replicates were carried out. The results show that I. badionotus has a higher distribution on the East coast of the island, and is found over Thalassia testudinum beds or bivalve molluscs aggregations, with an average density of 0.011 ind/m2, C.I. 95% = 0.005-0.017, n = 122, and a general abundance estimated in 117 ind/ha. H. mexicana has been practically depleted (0.001 ind/m2 C.I. 95% = 0.0002-0.0013, 7.7 ind/ha, n = 8). We recommend the maintenance of the total ban adopted in 1997 to assure the protection of these species, mainly because no previous data supported the start of the fishery, and also, because the current densities are still very low when compared to other areas in Venezuela and the Caribbean. These are animals easy to catch, susceptible to overfishing, and with a very low recovery rate; thus, more control is required from the local authorities. PMID:21721242

Tagliafico, Alejandro; Rangel, María Salomé; Rago, Néstor

2011-06-01

208

Integrated foraminiferal biostratigraphy and chemostratigraphy of the querecual formation (Cretaceous), Eastern Venezuela  

USGS Publications Warehouse

An integrated foraminiferal biostratigraphy and chemostratigraphy is presented for the Lower to Upper Cretaceous Querecual Formation exposed on Chimana Grande Island, Eastern Venezuela. The formation consists of >450 m alternating foraminiferal and organic-rich carbonates and laminated mudrocks, and is considered the main hydrocarbon source rock for the eastern Venezuela Basin. Biostratigraphic resolution within the Querecual Formation is poor, due to a paucity of keeled planktonic foraminifera and impoverished benthic faunas. Deposition occurred in a bathyal environment, with dysaerobic or anoxic bottom waters resulting from high rates of surface productivity associated with an upwelling environment. Biostratigraphic evidence indicates that the Querecual Formation ranges from the upper Albian Rotalipora ticinensis Zone to the Santonian Dicarinella asymetrica Zone. Iron and Al contents fall through the Albian-Cenomanian indicating a progressive decrease in the detrital supply, driven by rising eustatic sea level. A Ca profile demonstrates variations in carbonate production and dissolution. High total organic carbon (TOC) intervals occur in the upper Albian to mid-Cenomanian and Turonian, and high Ba/Al and Si/Al ratios characterize mid-Cenomanian and younger sediments. Variations in these elements primarily reflect changes in marine productivity, but are also affected by diagenetic processes. A stable carbon isotope curve established from analysis of organic matter (??13Corg) correlates well with published ??13C curves for carbonates from England and Italy. The Cenomanian/Turonian boundary cannot be identified using planktonic foraminifera, because key taxa are absent, but the base of the Turonian is clearly indicated by a sharp fall in ??13C immediately above a major positive excursion. The bottom of the Coniacian is placed below a ??13C minimum, towards the base of the Dicarinella concavata Zone. Combined with the foraminiferal data, the isotopic data enable much improved stratigraphic resolution compared to previous investigations of the formation.

Crespo, De Cabrera, S.; Sliter, W. V.; Jarvis, I.

1999-01-01

209

CONTAMINACIÓN DE SUELOS CON HUEVOS DE Toxocara spp. (NEMATODA, ASCARIDIDA) EN PARQUES PÚBLICOS DE LA CIUDAD DE CORO, ESTADO FALCÓN, VENEZUELA. Soil Contamination With Toxocara spp. Eggs (Nematoda, Ascaridida) in Public Parks From Coro City, Falcon State, Venezuela  

Microsoft Academic Search

A descriptive and transversal survey to establish contamination with Toxocara spp. eggs of soils from 38 public parks of the city of Coro, Falcon State, Venezuela, was carried out between February-March 2004. The soil samples were parasitologically processed using the technique of flotation with NaCl (modified Willis-Molloy). Texture, salinity (electric conductivity) and pH of the soils were also analyzed. Toxocara

Dalmiro José Cazorla Perfetti; Pedro Morales Moreno; María Eugenia; Acosta Quintero

210

Isolation and structure determination of novamethymycin, a new bioactive metabolite of the methymycin biosynthetic pathway in Streptomyces venezuelae.  

PubMed

Novamethymycin (9), a novel macrolide antibiotic, was isolated from Streptomyces venezuelae, the producer of methymycin (4) and neomethymycin (5). Spectroscopic analysis of 9 indicated that it is highly related to 4 and 5 but contains hydroxy groups at both C-10 and C-12 on the macrolactone ring. Bioconversion studies using the PikC cytochrome P450 hydroxylase demonstrated that 4 is converted to 9, further broadening the remarkable substrate flexibility of this enzyme. PMID:11720530

Zhang, Q; Sherman, D H

2001-11-01

211

Beta-glucosylation as a part of self-resistance mechanism in methymycin/pikromycin producing strain Streptomyces venezuelae.  

PubMed

In our study of the biosynthesis of D-desosamine in Streptomyces venezuelae, we have cloned and sequenced the entire desosamine biosynthetic cluster. The deduced product of one of the genes, desR, in this cluster shows high sequence homology to beta-glucosidases, which catalyze the hydrolysis of the glycosidic linkages, a function not required for the biosynthesis of desosamine. Disruption of the desR gene led to the accumulation of glucosylated methymycin/neomethymycin products, all of which are biologically inactive. It is thus conceivable that methymycin/neomethymycin may be produced as inert diglycosides, and the DesR protein is responsible for transforming these antibiotics from their dormant to their active forms. This hypothesis is supported by the fact that the translated desR gene has a leader sequence characteristic of secretory proteins, allowing it to be transported through the cell membrane and hydrolyze the modified antibiotics extracellularly to activate them. Expression of desR and biochemical characterization of the purified protein confirmed the catalytic function of this enzyme as a beta-glycosidase capable of catalyzing the hydrolysis of glucosylated methymycin/neomethymycin produced by S. venezuelae. These results provide strong evidence substantiating glycosylation/deglycosylation as a likely self-resistance mechanism of S. venezuelae. However, further experiments have suggested that such a glycosylation/deglycosylation is only a secondary self-defense mechanism in S. venezuelae, whereas modification of 23S rRNA, which is the target site for methymycin and its derivatives, by PikR1 and PikR2 is a primary self-resistance mechanism. Considering that postsynthetic glycosylation is an effective means to control the biological activity of macrolide antibiotics, the availability of macrolide glycosidases, which can be used for the activation of newly formed antibiotics that have been deliberately deactivated by engineered glycosyltransferases, may be a valuable part of an overall strategy for the development of novel antibiotics using the combinatorial biosynthetic approach. PMID:14674753

Zhao, Lishan; Beyer, Noelle J; Borisova, Svetlana A; Liu, Hung-wen

2003-12-23

212

Role of extensional tectonics in exhumation of eclogites and blueschists in an oblique subduction setting: Northeastern Venezuela  

Microsoft Academic Search

Eclogites and blueschists in northeastern Venezuela belong to a mid- to Late Cretaceous subduction complex-fore-arc terrane related to right-oblique subduction of the Proto-Caribbean plate beneath the Farallon plate along the Leeward Antilles volcanic island arc. These rocks were metamorphosed at high pressures and subsequently underwent retrogradation at decreasing pressures but at constant or slightly increasing temperatures. They underwent five phases

Hans G. Avé Lallemant; Lawrence R. Guth

1990-01-01

213

N2O and NO emissions from soils of the Northern Part of the Guayana Shield, Venezuela  

Microsoft Academic Search

Soil fluxes of N2O and No were measured in a scrub grass savanna and a nearby semideciduous forest in the savanna climatic region of Venezuela, during October 1988. The forest soil produces significantly larger emissions of N2O (ranging from 5.7 to 25.0×109 molecules cm-2 s-1) than the savanna soil (-3.6 to 14.0×109 molecules cm-2 s-1). This suggests that ``long term''

Eugenio Sanhueza; Dieter Scharffe; Loreto Donoso; Paul J. Crutzen

1990-01-01

214

Molecular characterisation of Mycobacterium tuberculosis isolates in the First National Survey of Anti-tuberculosis Drug Resistance from Venezuela  

PubMed Central

Background Molecular typing of Mycobacterium tuberculosis strains has become a valuable tool in the epidemiology of tuberculosis (TB) by allowing detection of outbreaks, tracking of epidemics, identification of genotypes and transmission events among patients who would have remained undetected by conventional contact investigation. This is the first genetic biodiversity study of M. tuberculosis in Venezuela. Thus, we investigated the genetic patterns of strains isolated in the first survey of anti-tuberculosis drug-resistance realised as part of the Global Project of Anti-tuberculosis Drug Resistance Surveillance (WHO/IUATLD). Results Clinical isolates (670/873) were genotyped by spoligotyping. The results were compared with the international spoligotyping database (SpolDB4). Multidrug resistant (MDR) strains (14/18) were also analysed by IS6110-RFLP assays, and resistance to isoniazid and rifampicin was characterised. Spoligotyping grouped 82% (548/670) of the strains into 59 clusters. Twenty new spoligotypes (SITs) specific to Venezuela were identified. Eight new inter-regional clusters were created. The Beijing genotype was not found. The genetic network shows that the Latin American and Mediterranean family constitutes the backbone of the genetic TB population-structure in Venezuela, responsible of >60% of total TB cases studied. MDR was 0.5% in never treated patients and 13.5% in previously treated patients. Mutations in rpoB gene and katG genes were detected in 64% and 43% of the MDR strains, respectively. Two clusters were found to be identical by the four different analysis methods, presumably representing cases of recent transmission of MDR tuberculosis. Conclusion This study gives a first overview of the M. tuberculosis strains circulating in Venezuela during the first survey of anti-tuberculosis drug-resistance. It may aid in the creation of a national database that will be a valuable support for further studies.

Aristimuno, Liselotte; Armengol, Raimond; Cebollada, Alberto; Espana, Mercedes; Guilarte, Alexis; Lafoz, Carmen; Lezcano, Maria A; Revillo, Maria J; Martin, Carlos; Ramirez, Carmen; Rastogi, Nalin; Rojas, Janet; de Salas, Albina Vazques; Sola, Christophe; Samper, Sofia

2006-01-01

215

Genetic History of Hepatitis C Virus in Venezuela: High Diversity and Long Time of Evolution of HCV Genotype 2  

PubMed Central

Background The subtype diversity of the hepatitis C virus (HCV) genotypes is unknown in Venezuela. Methodology/Principal Findings Partial sequencing of the NS5B region was performed in 310 isolates circulating in patients from 1995 to 2007. In the samples collected between 2005 and 2007, HCV genotype 1 (G1) was the most common genotype (63%), composed as expected of mainly G1a and G1b. G2 was the second most common genotype (33%), being G2a almost absent and G2j the most frequent subtype. Sequence analysis of the core region confirmed the subtype assignment performed within the NS5b region in 63 isolates. The complete genome sequence of G2j was obtained. G2j has been described in France, Canada and Burkina Fasso, but it was not found in Martinique, where several subtypes of G2 circulate in the general population. Bayesian coalescence analysis indicated a most recent common ancestor (MRCA) of G2j around 1785, before the introduction of G1b (1869) and G1a (1922). While HCV G1a and G1b experienced a growth reduction since 1990, coincident with the time when blood testing was implemented in Venezuela, HCV G2j did not seem to reach growth equilibrium during this period. Conclusions/Significance Assuming the introduction of G2j from Africa during the slave trade, the high frequency of G2j found in Venezuela could suggest: 1- the introduction of African ethnic groups different from the ones introduced to Martinique or 2- the occurrence of a founder effect. This study represents an in-depth analysis of the subtype diversity of HCV in Venezuela, which is still unexplored in the Americas and deserves further studies.

Sulbaran, Maria Z.; Di Lello, Federico A.; Sulbaran, Yoneira; Cosson, Clarisa; Loureiro, Carmen L.; Rangel, Hector R.; Cantaloube, Jean F.; Campos, Rodolfo H.; Moratorio, Gonzalo; Cristina, Juan; Pujol, Flor H.

2010-01-01

216

Isotopic signatures and nutrient relations of plants inhabiting brackish wetlands in the northeastern coastal plain of Venezuela  

Microsoft Academic Search

The semi-diurnal tidal regime (?2 m) in the Paria Gulf on the Atlantic coast of Venezuela, and the flat landscape of the region,\\u000a allow the penetration for tens of km of marine waters into the rivers draining the northeastern coastal plain of the country.\\u000a The levels of salinity, tidal flooding, and sedimentation decrease perpendicularly from the river channel toward the back

Ernesto Medina; Marta Francisco; Antonio Quilice

2008-01-01

217

Geochemistry of a tropical lake (Lake Leopoldo) on pseudo-karst topography within the Roraima Group, Guayana Shield, Venezuela  

Microsoft Academic Search

A geochemical assessment was performed on Lake Leopoldo, a tropical lake located on the Guayana Shield, Venezuela. The lake water was characterized (Ca2+, Mg2+, Na+, K+, Cl?, NO3-, NO2-, SO42-, NH4+, Fe, and P), lacustrine setting the origin, transport and fate of sedimentary material in this highly unusual lacustrine setting. Lake sediments were analyzed for textural, mineralogical and chemical composition,

Carlos Yanes; Haymara Alvarez; Rudolf Jaffé

2006-01-01

218

An acyl-coenzyme A carboxylase encoding gene associated with jadomycin biosynthesis in Streptomyces venezuelae ISP5230  

Microsoft Academic Search

Analysis of a region of chromosomal DNA lying between jadR1 and jadI in the gene cluster for jadomycin biosynthesis in Streptomyces venezuelae ISP5230 detected an ORF encoding 584 amino acids similar in sequence to the biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) components of acyl-coenzyme A carboxylases. Multiple sequence alignments of the deduced Jad protein with acyl-coenzyme A

L. Han; K. Yang; K. Kulowski; E. Wendt-Pienkowski; C. R. Hutchinson; L. C. Vining

219

COMPARACIÓN DE MÉTODOS PARA EL ANÁLISIS DE MERCURIO EN SUELOS PROCEDENTES DE EL CALLAO, ESTADO BOLÍVAR, VENEZUELA  

Microsoft Academic Search

SUMMARY Mercury levels in soil samples from El Callao, Bolívar State, Venezuela, were determined by mineralization in aqua regia followed by cold vapor-atomic absorption spectrometry (CVAAS), and by direct determination on solid matrix by pyrolisis and preconcentration using an automatic mercury analyzer AMA-254 (AMA). Hg concentration in samples were in the range of 0.05 to 17.31mg\\/kg for CVAAS and of

Armando Carrasquero Durán; Melitón Adams

220

The preliminary results of the measurements of environmental levels of 40K and 137Cs in Venezuela  

Microsoft Academic Search

The study of the beta-particle radioactivity in air and 90Sr in rainwater collected at Instituto Venezolano de Investigaciones Cientificas, IVIC, that began in 1959 in conjunction with the U.S. Atomic Energy Commission was discontinued in 1963. But after the Chernobyl nuclear power plant accident in the USSR, work on the radioactive contamination in Venezuela has been renewed. Initially the measurement

J. J. Labrecque; P. A. Rosales; O. Carias

1992-01-01

221

Genetic History of Hepatitis C Virus in Venezuela: High Diversity and Long Time of Evolution of HCV Genotype 2  

Microsoft Academic Search

BackgroundThe subtype diversity of the hepatitis C virus (HCV) genotypes is unknown in Venezuela.Methodology\\/Principal FindingsPartial sequencing of the NS5B region was performed in 310 isolates circulating in patients from 1995 to 2007. In the samples collected between 2005 and 2007, HCV genotype 1 (G1) was the most common genotype (63%), composed as expected of mainly G1a and G1b. G2 was

Maria Z. Sulbarán; Federico A. di Lello; Yoneira Sulbarán; Clarisa Cosson; Carmen L. Loureiro; Héctor R. Rangel; Jean F. Cantaloube; Rodolfo H. Campos; Gonzalo Moratorio; Juan Cristina; Flor H. Pujol; Sheila Mary Bowyer

2010-01-01

222

Extreme Sr–Nd–Pb–Hf isotopic compositions exhibited by the Tinaquillo peridotite massif, Northern Venezuela: implications for geodynamic setting  

Microsoft Academic Search

An origin of the Tinaquillo Peridotite Complex in northern Venezuela, and a model for the tectonic framework of the boundary\\u000a zone between the southern Caribbean Plate margin and the South American Plate (SAP) during Late Jurassic to Mid-Cretaceous\\u000a time are developed using newly measured Sr, Nd, Pb and Hf isotopic compositions as well as major and trace element geochemistry\\u000a for

Sung Hi Choi; Samuel B. Mukasa; Alexandre V. Andronikov; Maria C. Marcano

2007-01-01

223

Tomato chlorotic leaf distortion virus, a new bipartite begomovirus infecting Solanum lycopersicum and Capsicum chinense in Venezuela  

Microsoft Academic Search

Virus isolate T217L was obtained from a diseased tomato (Solanum lycopersicum) plant showing leaf deformation and chlorotic mottle symptoms near Maracaibo in the state of Zulia, Venezuela. Full-length\\u000a DNA-A and DNA-B molecules of T217L were cloned and sequenced. The genome organization of T217L was identical to the bipartite\\u000a genomes of other begomoviruses described from the Americas. Characteristic disease symptoms were

Karla Zambrano; Francis Geraud-Pouey; Doris Chirinos; Gustavo Romay; Edgloris Marys

224

Genetically engineered biosynthesis of macrolide derivatives including 4-amino-4,6-dideoxy-L-glucose from Streptomyces venezuelae YJ003-OTBP3.  

PubMed

Two sugar biosynthetic cassette plasmids were used to direct the biosynthesis of a deoxyaminosugar. The pOTBP1 plasmid containing TDP-glucose synthase (desIII), TDP-glucose-4,6-dehydratase (desIV), and glycosyltransferase (desVII/desVIII) was constructed and transformed into S. venezuelae YJ003, a strain in which the entire gene cluster of desosamine biosynthesis is deleted. The expression plasmid pOTBP3 containing 4-aminotransferase (gerB) and 3,5-epimerase (orf9) was transformed again into S. venezuelae YJ003- OTBP1 to obtain S. venezuelae YJ003-OTBP3 for the production of 4-amino-4,6-dideoxy-L-glucose derivatives. The crude extracts obtained from S. venezuelae ATCC 15439, S. venezuelae YJ003, and S. venezuelae YJ003-OTBP3 were further analyzed by TLC, bioassay, HPLC, ESI/MS, LC/MS, and MS/MS. The results of our study clearly shows that S. venezuelae YJ003-OTBP3 constructs other new hybrid macrolide derivatives including 4-amino-4,6-dideoxy-L-glycosylated YC-17 (3, [M+ Na+] m/z=464.5), methymycin (4, m/z=480.5), novamethymycin (6, m/z=496.5), and pikromycin (5, m/z=536.5) from a 12- membered ring aglycon (10-deoxymethynolide, 1) and 14-membered ring aglycon (narbonolide, 2). These results suggest a successful engineering of a deoxysugar pathway to generate novel hybrid macrolide derivatives, including deoxyaminosugar. PMID:18239422

Pageni, Binod Babu; Oh, Tae-Jin; Liou, Kwangkyoung; Yoon, Yeo Joon; Sohng, Jae Kyung

2008-01-01

225

Estudio Integral de Desarrollo e Inversiones del Sistema Aeroportuario y de Rutas Aereas de Venezuela. Fase 1. Informe Final. Volumen 1 (Comprehensive Study of the Development and Investment Requirements of the Airspace and Airport System of Venezuela. Phase 1. Volume 1).  

National Technical Information Service (NTIS)

The report, written in Spanish, presents the results of a Feasibility Study prepared by AAROTEC/Airways Engineering Associates and Louis Berger International for the Ministry of Transportation and Communications of Venezuela. The report discusses the expa...

1993-01-01

226

Geophysical studies for the identification of basin effects in urban areas in Venezuela  

NASA Astrophysics Data System (ADS)

Urban areas in northern Venezuela are subject to a moderate seismic hazard due to the interactions between the Caribbean and south American plates, which has been evidenced by historical damaging earthquakes as for example the 1812 and the 1967 earthquakes with a magnitude of 7.2 and 6.5, respectively. Strong damages in Caracas during the 1967 earthquake have been asociated to site effects produced by the sediment filled basin. This situation can be observed in most of the big cities in northern Venezuela, which initially developped on plain areas with quaternary basin fills of up to 500 m within mountainous areas, as for example Caracas, Maracay and Barquisimeto. In the mid- 1990ies FUNVISIS started to promote geophysical studies to investigate the shape and the properties of the basin fills in order to contribute to the earthquake disaster reduction. Methods applied for the investigations are gravimetry, microtremor measurements, seismic refraction, among others. In Caracas, a total of 350 m of cuaternary sediments with an average S-wave velocity of about 850 m/s have been derived by seismic investigations. The corresponding predominant periods from microtremor measurements amount up to 2.2 s. Integrating drilling information and 3D gravimetric modeling a detailed picture of the bedrock - sediment interface could be obtained. Results from numerical modelling as well as from experimental transfer function indicate amplifications point to amplifications of a factor of more than 10 related to the deep basin area. In Barquisimeto Metropolitan Area, sediment thickness reaches up to 500 m in the fast growing Cabudare area. Actually, modelling of a recent seismic refraction campaign is in progress, but predominant periods up to 3.0 s in the deepest part of the valley and gravity modelling point to the same order of cuaternary sediments. In other cities, as for example Carora and Mérida, geophysical studies are in progress, first with gravimetric and microtremor measurements which point to sediment with more than 150 m thickness. The subsoil information from geophysical studies will be used to define the distribution of microzones of equal seismic response in order to determine PSHA spectra. Contribution to projects FONACIT 200400738 and FONACIT-ECOS Nord 2004000347.

Schmitz, M.; Rocabado, V.; Sánchez, J.; Reinoza, C.; Amaris, E.; Cornou, C.

2007-05-01

227

Embrionary and larval development of the marine clam Tivela mactroides (Bivalvia: Veneridae) in Zulia State, Venezuela.  

PubMed

The marine clam, Tivela mactroides, from Caño Sagua beach, Venezuela, was spawned and reared under laboratory conditions to monitor its early development. Spawning was spontaneous but in some cases it had to be induced by the additon of eggs and sperm. After fertilization, the embryonic development occurred at 5 hr approximately. Trochophore larvae were observed between eight and ten hours later. Straight-hinged veliger stage appeared 15 hr after fertilization. Transition from veliger stage to the umbo stage occurred about eight days after fertilization. Pediveliger stage was observed 22 days after fertilization. Metamorphosis of T. mactroides was not successful under our laboratory conditions; probably the bacterial contamination and subsequent mortalities were important factors constraining the final phase of the larval cycle. However, in a few cases young individuals were observed. We suspect that this was due to unfavorable conditions (e.g.: bacterial contamination, unsuitable food availability, etc.) and the broad variation in developmental times, suggesting that these stages might be particularly sensitive to environmental changes. These results may not necessarily reflect what happens under natural conditions. PMID:17354399

Reverol, Yinett M; Delgado, José G; de Severeyn, Yajaira G; Severeyn, Héctor J

2004-12-01

228

A gene cluster for macrolide antibiotic biosynthesis in Streptomyces venezuelae: Architecture of metabolic diversity  

PubMed Central

In a survey of microbial systems capable of generating unusual metabolite structural variability, Streptomyces venezuelae ATCC 15439 is notable in its ability to produce two distinct groups of macrolide antibiotics. Methymycin and neomethymycin are derived from the 12-membered ring macrolactone 10-deoxymethynolide, whereas narbomycin and pikromycin are derived from the 14-membered ring macrolactone, narbonolide. This report describes the cloning and characterization of the biosynthetic gene cluster for these antibiotics. Central to the cluster is a polyketide synthase locus (pikA) that encodes a six-module system comprised of four multifunctional proteins, in addition to a type II thioesterase (TEII). Immediately downstream is a set of genes for desosamine biosynthesis (des) and macrolide ring hydroxylation. The study suggests that Pik TEII plays a role in forming a metabolic branch through which polyketides of different chain length are generated, and the glycosyl transferase (encoded by desVII) has the ability to catalyze glycosylation of both the 12- and 14-membered ring macrolactones. Moreover, the pikC-encoded P450 hydroxylase provides yet another layer of structural variability by introducing regiochemical diversity into the macrolide ring systems. The data support the notion that the architecture of the pik gene cluster as well as the unusual substrate specificity of particular enzymes contributes to its ability to generate four macrolide antibiotics.

Xue, Yongquan; Zhao, Lishan; Liu, Hung-wen; Sherman, David H.

1998-01-01

229

A gene cluster for macrolide antibiotic biosynthesis in Streptomyces venezuelae: architecture of metabolic diversity.  

PubMed

In a survey of microbial systems capable of generating unusual metabolite structural variability, Streptomyces venezuelae ATCC 15439 is notable in its ability to produce two distinct groups of macrolide antibiotics. Methymycin and neomethymycin are derived from the 12-membered ring macrolactone 10-deoxymethynolide, whereas narbomycin and pikromycin are derived from the 14-membered ring macrolactone, narbonolide. This report describes the cloning and characterization of the biosynthetic gene cluster for these antibiotics. Central to the cluster is a polyketide synthase locus (pikA) that encodes a six-module system comprised of four multifunctional proteins, in addition to a type II thioesterase (TEII). Immediately downstream is a set of genes for desosamine biosynthesis (des) and macrolide ring hydroxylation. The study suggests that Pik TEII plays a role in forming a metabolic branch through which polyketides of different chain length are generated, and the glycosyl transferase (encoded by desVII) has the ability to catalyze glycosylation of both the 12- and 14-membered ring macrolactones. Moreover, the pikC-encoded P450 hydroxylase provides yet another layer of structural variability by introducing regiochemical diversity into the macrolide ring systems. The data support the notion that the architecture of the pik gene cluster as well as the unusual substrate specificity of particular enzymes contributes to its ability to generate four macrolide antibiotics. PMID:9770448

Xue, Y; Zhao, L; Liu, H W; Sherman, D H

1998-10-13

230

[Diversity and abundance of mollusks in the sublittoral epifaunal community of Punta Patilla, Venezuela].  

PubMed

The diversity of a sublittoral epifaunal mollusk community of Punta Patilla, Sucre State, Venezuela, was studied from September 1990 to September 1991. We identified 25 species (14 bivalves and 11 gastropods) of mollusks that inhabit gravel, soft sand and bottoms covered by Thalassia testudinum. Total diversity indices were H' = 3.42. J' = 0.74 and 1-D = 0.85. Monthly diversity reached its maximum in March 1991 (3.12 bits/ ind.), June 1991 (2.88 bits/ind.) and September 1991 (2.95 bits/ind.); minimum diversity was recorded in August 1991 (1.20 bits/ind.). A log series model showed a diversity index alpha = 4.56 for species abundance data and alpha = 3.11 for biomass data. The more abundant species were Chione cancellata, Anigona listeri, Chione granulata and Area zebra among the bivalves, and Chicoreus brevifrons, Turritella variegata and Phllonotus pomum among the gastropods (which present maximum biomass). The average total biomass (56.80 g/m2) is low when compared to reports from other tropical zones. PMID:17354426

Prieto, Antulio; Ruiz, Lilia J; García, Natividad

231

Household social determinants of ascariasis and trichuriasis in North Central Venezuela.  

PubMed

Ascariasis and trichuriasis are highly prevalent parasitoses in tropical countries caused by Ascaris lumbricoides and Trichuris trichiura, respectively. Their prevalence is associated with poor sanitation and hygiene, among other biological and social factors. In this study, the associations of household social determinants with these soil-transmitted helminthiases in North Central Venezuela was assessed in the context of a National Study on Human Growth and Development (SENACREDH). This was a probabilistic, stratified, cross-sectional survey with a sample of 3388 individuals that weighted represents 4 675 433 inhabitants from the region. The prevalence of ascariasis and trichuriasis was 3.73% and 1.13%, respectively. In the univariate and multivariate analyses, these prevalences were significantly higher in those living in vulnerable houses [adjusted OR (AOR) = 1.479, 95% CI 1.428-1.532; and AOR = 10.519, 95% CI 9.971-11.097, respectively], houses located in rural areas (AOR = 2.067, 95% CI 2.035-2.101; and AOR = 1.918, 95% CI 1.868-1.970, respectively) and houses with a soil floor (AOR = 5.027, 95% CI 4.895-5.162; and AOR = 5.190, 95% CI 4.944-5.448, respectively), among other factors. People living in rural households with inappropriate building materials, insufficient basic public services such as water and waste disposal, and surrounding disease-prone environments are at higher risk of acquiring A. lumbricoides and T. trichiura infections. PMID:24029148

Quintero, Karen; Durán, Carmen; Duri, Deborah; Medina, Flor; Garcia, Josmar; Hidalgo, Glida; Nakal, Syndy; Echeverria-Ortega, Maria; Albano, Carlos; Incani, Renzo Nino; Cortez, Jackeline; Jiménez, Sara; Díaz, Marietta; Maldonado, Cecilio; Matute, Franklin; Rodriguez-Morales, Alfonso J

2012-06-01

232

Assessment of waterborne protozoan passage through conventional drinking water treatment process in Venezuela.  

PubMed

Three drinking water treatment plants (DWTPs) differing in source water and treatment capacity were investigated for the potential passage of waterborne protozoan (oo)cysts through conventional processing. DWTP I (15,000 L/s), DWTP II (7,500 L/s) and DWTP III (4,300 L/s) provide drinking water for approximately 2.7 million inhabitants of the Metropolitan District of Caracas (Venezuela). The US Environmental Protection Agency Method 1623 for detection of Cryptosporidium and Giardia was used to analyze raw water and finished drinking water samples collected from the three plants. (Oo)cyst recovery efficiencies varied between 23 and 84%. The concentration of confirmed (oo)cysts detected in raw water samples ranged between 1 and 100 per 100 L. (Oo)cyst levels in finished water samples ranged from 2 to 25 per 100 L. These data indicated that the conventional treatment process to produce finished water at two filtration plants was not effective in preventing the passage of protozoan (oo)cysts. Monitoring strategies that include multiple microbial indicators and waterborne pathogens are strongly recommended for accurate source water characterization and for verification of the effectiveness of treatment process barriers to microbial breakthrough in the finished water. PMID:22717757

Betancourt, Walter Q; Mena, Kristina D

2012-06-01

233

Geology and geochemistry of the La Luna Formation type sections in the Maracaibo basin, Venezuela  

SciTech Connect

The Upper Cretaceous La Luna Formation is the most important source rock of hydrocarbons in Western Venezuela. Curiously enough it has two type sections, the formation was first defined in 1926 in Perija on the western flank of the Maracaibo basin; 30 years later the La Aguada, Chejende and Timbetes members were defined 260 km toward the east, on the shelf of the basin. The purpose of this study is to compare these sections and to define the vertical and horizontal variability of geological and geochemical characteristics that might have influenced the generation of hydrocarbons. The study consisted of detailed, bed level sampling, macroscopic sedimentary descriptions, petrography of 168 thin sections with 40 variables recorded in a statistical data matrix for determination of lithomicrofacies, as well as geochemical analysis of total organic carbon (TOC), visual kerogen, Rock-Eval pyrolysis and gas chromatography. The western type section is characterized by alternating thinly laminated and massive bedded limestones. Thermally immature, amorphous organic matter of marine origin is abundant in this section; TOC values range from 0.23% to 8.56%, generally increasing toward the top. Hydrogen index values range from 327 to 1078, indicating good to excellent oil generating potential. The eastern type sections have a higher level of thermal maturity; they show increasing amounts of clastic material, less authigenic minerals and abundant Favreina sp crab fecal pellets. The mainly terrestrially derived organic matter concentrations are considerably less, ranging from 0.07 to 3.39, again increasing toward the top of the section.

Baptista, N.; Scherer, W. [Logoven, S.A., Tamare, and Intevep, S.A., Los Teques (Venezuela)

1996-08-01

234

[Geometric wing morphometrics for Chrysomya albiceps and C. megacephala identification (Diptera: Calliphoridae) from Venezuela].  

PubMed

Calliphoridae is one of the families with the greatest number of species with forensic importance, which immature stages feed and develop on decaying material. In Venezuela, there are few studies on this taxon reporting the dominance of Chrysomya over other carrion flies. The goal of this study was to analyze the variations on wing morphometrics, to support the identification of two forensic flies. For this we photographed a total of 168 wings from C. albiceps (n=111) and C. megacephala (n=57). Landmark coordinate (x, y) configurations were registered and aligned by Generalized Procrustes Analysis. Principal Component Analysis and shape significance test based on Procrustes distance were implemented. Statistical analysis of variance found significant differences in wing isometric size (Kruskal-Wallis). The PCA showed the separation between species, and shape test showed significant differences (F Goodall's). The main differences between both species were localized on subcosta rupture, join of R(2+3) with wing border, join of dm-cu, and join of Cu with bm-cu, suggesting that wing morphometrics is a suitable tool in the discrimination of blowfly species. PMID:23025095

Vásquez, Marianela; Liria, Jonathan

2012-09-01

235

Malaria entomological risk factors in relation to land cover in the Lower Caura River Basin, Venezuela.  

PubMed

To explore the effects of deforestation and resulting differences in vegetation and land cover on entomological parameters, such as anopheline species composition, abundance, biting rate, parity and entomological inoculation rate (EIR), three villages were selected in the Lower Caura River Basin, state of Bolívar, Venezuela. All-night mosquito collections were conducted between March 2008-January 2009 using CDC light traps and Mosquito Magnet® Liberty Plus. Human landing catches were performed between 06:00 pm-10:00 pm, when anophelines were most active. Four types of vegetation were identified. The Annual Parasite Index was not correlated with the type of vegetation. The least abundantly forested village had the highest anopheline abundance, biting rate and species diversity. Anopheles darlingi and Anopheles nuneztovari were the most abundant species and were collected in all three villages. Both species showed unique biting cycles. The more abundantly forested village of El Palmar reported the highest EIR. The results confirmed previous observations that the impacts of deforestation and resulting changes in vegetation cover on malaria transmission are complex and vary locally. PMID:23579803

Rubio-Palis, Yasmin; Bevilacqua, Mariapia; Medina, Domingo Alberto; Moreno, Jorge Ernesto; Cárdenas, Lya; Sánchez, Víctor; Estrada, Yarys; Anaya, William; Martínez, Ángela

2013-04-01

236

Integrating complexity of social systems in natural hazards planning: An example from Caracas, Venezuela  

NASA Astrophysics Data System (ADS)

In December 1999, days of heavy rain on steep slopes north of Caracas, Venezuela triggered massive mud and debris flows, killing tens of thousands. Partly in response to this disaster, a multidisciplinary team of urban planners and Earth scientists from Columbia University recently developed a framework plan for building disaster resilience into the Venezuelan capital region. After assessing the complex intersection of urban geography with severe seismic and hydrologic hazards, substantial recommendations were made to local and regional authorities on future hazards mitigation.Areas found most at risk in the Caracas region include the transportation and utility infrastructure and the friable building stock of squatter settlements. Recognizing realistic economic and socio-political constraints on implementing change, a prioritized list of goals and activities was constructed, and recommendations made along various time scales. Immediate disaster-avoidance goals (to be completed within 1 to 5 years) include strengthening critical infrastructure nodes, housing stock, and emergency services. More intermediate goals (5 to 10 years) focus on upgrading fragile housing units, creating detailed hazard maps across the city, and incorporating disaster education into cultural activities. Recommended activities for the long term (beyond 10 years) include creating a fully redundant transportation and water delivery network, establishing legitimate land title for squatters, and re-locating critical facilities currently in high-risk areas.

Vranes, Kevin; Czuchlewski, Kristina R.

237

Biostratigraphic sequence analysis of Oligocene-Lower Miocene sections in the Orocual Field, Eastern Venezuela Basin  

SciTech Connect

A detailed biostratigraphic study of the Oligocene-Miocene boundary was carried out in sections 1000 ft thick of ten wells of the Orocual Field, Eastern Venezuela, The sequences under investigation carry a rich microfauna of benthic and planktonic foraminifera and calcareous nannoplankton. About 500 samples were analyzed and nearly 150 species of foraminifera and 60 of nannoplankton calcareous were identified. The planktonic assemblages allow the identification of zones N3 and N4 of Blow, 1969; zones NP23, NP24, NP25 and NN1 of Martini, 1971; and zones F and E of Stainforth et al., 1959 of the Carapita Formation. The paleoenvironments of these sediments were determined rather precisely and vary from inner shelf to middle slope. Paleobathymetric curves of several wells are included. High and low fossil abundance and diversity peaks were used to recognize two sequences of the third order and five of the fourth order between 24.8 Ma and 26.5 Ma. A generalized transgressive trend is evident from the Late Oligocene to the Early Miocene.

Giffuni, G.; Castro-Mora, M. [Departamento de Geologia, Lagoven, S.A., Caracas (Venezuela)

1996-08-01

238

[Soil microbial activity variation after land use changes in savannah, Llanos Orientales, Venezuela].  

PubMed

In West plains of Venezuela, the traditional land use of the Trachypogon savannah, has been the extensive grazing. The pressure over these savannahs to obtain a major animal productivity has stimulated the introduction of exotic forage plants, such as Brachiaria brizantha and Andropogon gayanus. In spite that great savannah extensions have been subject to this land use change, information about the effect that pastures and grazing activity have on microbial activity in these soils is scarce. So the objective of this study was to determine the impact that the extensive grazing and cover substitution have on microbial activity. The soil sampling was carried out during the dry and rainy seasons. The employed parameters to determine changes in soil microbial activity were the substrate induced respiration (SIR), basal respiration (BR), the dehydrogenase activity (DHS), the fluorescein diacetate hydrolysis (FDA) and the arginene ammonification (AA). The similarity of the structural soil characteristics studied allows us to infer, that the differences in the microbiological parameters are determined by climatic conditions and soil management. The results show that there is a low microbial activity in these soils. The rainy season caused an increase in all the microbiological parameters determined. B. brizantha made a greater contribution to soil carbon and promoted a greater heterotrophic activity. The extensive grazing and the low stocking rate in the West plain savannas did not affect the microbial activity in these soils. PMID:21516636

Gómez, Yrma; Paolini, Jorge

2011-03-01

239

Geological Studies in eastern Venezuela and Trinidad from Cretaceous passive margin to Neogene transpressional thrust belt  

SciTech Connect

Sedimentological and structural analyses of Trinidad's Northern and Central ranges and Venezuela's Serrania del Interior have led to new interpretations of northeastern. South America's tectonic evolution within the Southern Caribbean Plate Boundary Zone. Medial ( ) Jurassic through early Cenozoic passive margin sediments make up the majority of these areas and were deposited somewhat to the WNW (between 80 and 130 km for Northern Range of Trinidad) of their present positions prior to structural shortening. Neogene southeastward displacement of Jurassic-Cretaceous passive slope and rise sediments (Northern Range) drove propagation of thrusts southward into the Serrania and Central ranges. Displacements were driven by migration of the Caribbean Plate relative to South America. Thus, the Serrania and Central ranges are the western hemisphere's only exposed Mesozoic-Cenozoic passive Atlantic margin stratigraphic section. As such, they provide a Cretaceous-Paleogene record of passive margin sedimentation at a thermally subsiding margin where the complicating effects of tectonism are absent. This makes these sections especially suited for studies of eustatic sea level behavior. Preliminary assessments are shown which suggest that sea level changes for Cretaceous to Paleogene time are not as pronounced as the frequent large and rapid sea level falls and rises that are promoted by some.

Algar, S.T.; Erikson, J.E.; Pindell, J.L. (Dartmouth Coll., Hanover, NH (United States))

1991-03-01

240

[Distribution and taxonomy of Pyrgophorus platyrachis (Caenogastropoda: Hydrobiidae) in the Sistema de Maracaibo, Venezuela].  

PubMed

The presence of a microgastropod identified as Potamopyrgus sp. was detected previously in the Maracaibo System; nevertheless, a detailed morphological analysis identified this snail in other genera. The objective of this work is to update the distribution and taxonomy of Pyrgophorus platyrachis in the Maracaibo System, Venezuela in samples obtained between 2001 and 2009. The presence of hundreds of individuals of P. platyrachis were observed in the estuary, indeed in the localities of the Gran Eneal lagoon (4 111 snails), Peonías lagoon (229 snails), Punta Capitán Chico (758 snails), San Francisco (2 517 snails), Curarire (240 snails), Apon River mouth (173 snails), Ojeda City (240 snails), Bachaquero (128 snails) and Tomoporo de Agua (385 snails). We performed a taxonomical analysis, and emphasized in ecological aspects, such as the distribution of the species and habitat features, as near vegetation and type of associated sediment. We found three morphotypes of the species, one smooth, another with spiral striations and the other with spines. Smooth morphotype was exclusive of the Gran Eneal lagoon, Peonías lagoon, Punta Capitan Chico and Apon River mouth localities, whereas the other two morphotypes were found together in the remaining localities. According to our detailed anatomical and taxonomical analysis we propose a synonymy between P. platyrachis and the other species described like Pyrgophorus parvulus and Pyrgophorus spinosus. PMID:22017122

Nava, Mario; Severeyn, Héctor; Machado, Nakary

2011-09-01

241

Arbuscular mycorrhizas in coastal sand dunes of the Paraguaná Peninsula, Venezuela.  

PubMed

Arbuscular mycorrhizal colonization was measured in the most abundant plant species of the Paraguaná Peninsula, northwestern Venezuela. These plant species included: Acacia tortuosa, Argusia gnaphalodes, Croton punctatus, Croton rhamnifolius, Egletes prostrata, Melochia tomentosa, Panicum vaginatum, Scaevola plumieri, Sporobolus virginicus, Suriana maritima, Leptothrium rigidum, and Fimbristylis cymosa. Mycorrhizal colonization was assessed using the Trouvelot et al. (1986) method that allows for simultaneous evaluation of frequency of colonization (%F), intensity of colonization (%M), and the proportion of arbuscules (%A) and vesicles (%V) present in the roots. Average frequency of colonization was 69%. The highest frequency of colonization was around 92% in C. rhamnifolius and A. tortuosa; in the other species, it varied from 49 to 86%. L. rigidum and F. cymosa were considered nonmycorrhizal because its colonization was very scarce and at all times appeared without arbuscules. Average intensity of colonization was 7%. The highest intensity of colonization was 18% in C. rhamnifolius. In the other species, it varied from 3 to 15%. Paspalum vaginatum, A. gnaphalodes, M. tomentosa, and S. maritima had their fungal structures tightly packed in modified little ovoid roots. In general, frequency of AM colonization was high and similar to those reported for other tropical ecosystems, whereas the intensity of AM colonization was low and similar to values obtained in analogous studies in disturbed ecosystems. PMID:16007471

Alarcón, C; Cuenca, G

2005-11-11

242

Biostratigraphy of a Middle Miocene-Pliocene sequence from Cumarebo area, Falcon State, northwestern Venezuela  

SciTech Connect

The southern Caribbean region offers little in the way of continuous sequences for the late Neogene. An upward facies shallowing trend unfavorable for planktonic foraminifers and erosional truncation seems to be almost a rule for such sediments. A fairly complete sedimentary sequence mainly represented by clays, silts, and carbonate rocks from the Cumarebo region, Falcon State, northwestern Venezuela, was chosen to study the biostratigraphy of the late Neogene using foraminifers. More than one hundred surface samples were analyzed throughout. The study of foraminiferal fossil assemblages and other microfossils was also used to define paleoenvironments of deposition. Four formations are involved in this work. From base to top they are the Socorro, Caujarao, El Veral, and Tucupido. From the study of planktonic foraminifers, six biostratigraphic zones were recognized: Globorotalia mayeri Zone, Globorotalia menardii Zone, Globorotalia acostaensis Zone, Globorotalia humerosa Zone, Globorotalia margaritae Zone, and Globorotalia miocenica Zone. These zones indicate that the age of the sequence ranks from late middle Miocene to middle Pliocene. Generally speaking, with some variations, the paleoenvironments of the sequence show a shallowing trend from marine upper-middle bathyal to middle neritic. These results make an important contribution to the stratigraphy and geologic history of the Cumarebo area, which is related to the Agua Salada basin, and may help clarify the paleogeography and paleotectonic evolution of this region for petroleum exploration.

Giffuni, G. (INTEVEP, S.A., Caracas (Venezuela))

1991-03-01

243

Serological evidence of Neospora caninum in dual-purpose cattle herds in Venezuela.  

PubMed

Bovine neosporosis is a parasitic disease produced by Neospora caninum that induces abortion in cows, and consequently has a negative impact on the herd's reproductive efficiency. The main objective of this research was to determine the serological evidence of N. caninum in cattle herds from Venezuela using an indirect antibody capture ELISA test. Four hundred and fifty-nine (459) serum samples from crossbred adult cows were collected to be tested for Neospora antibodies. The sampled cows came from 15 large farms located in eight important cattle states that have predominant dual-purpose production systems (cattle from these farms are used for both milk and meat production). Fifty-two cows (11.3%) were seropositive to N. Caninum. Thirteen (86.7%) of 15 studied herds had cows seropositive to N. caninum. The average within-herd seroprevalence was 11.5% (range 3.8-36.7%). Cows that aborted in some of these farms had 2.71 (P: 0.009) greater odds to be seropositive when compared to cows that did not abort. Each one of the eight states represented in our study had seropositive animals. These results are the first evidence of exposure to N. caninum in Venezuelan cattle herds, indicating the possible circulation of this pathogen in the country. Further epidemiological studies should be granted to determine the spread of the disease in the Venezuelan cattle industry and its associated risk factors. PMID:16423467

Lista-Alves, D; Palomares-Naveda, R; Garcia, F; Obando, C; Arrieta, D; Hoet, A E

2006-01-19

244

Seismic hazard analysis of western Venezuela methodology and data collection process  

NASA Astrophysics Data System (ADS)

This project, initiated by INTEVEP, develops a seismic hazard characterization for the region of the Lake Maracaibo basin in Western Venezuela (WV) with an emphasis at the sites of dikes built on the eastern side of the lake. One task of the project was to assess the seismicity of this region and to describe it in a form which can be used as input to a seismic hazard analysis. The seismic parameters were seismo-tectonic zonation, distribution of earthquake magnitudes, and the largest earthquake, i.e., upper magnitude cutoff. Because it is difficult, or perhaps impossible, to precisely quantify such seismic parameters using only the sparse historical record, expert judgment is crucial. Thus two panels of experts were assembled to supplement the lack of opinions in the possible models of zonation, seismicity, (S-panel) and ground motion attenuation (G-panel). In addition to the ground motion models described in the ground motion questionnaire handed to the G-panel experts, we performed some analysis, at LLNL, to develop a new breed of models where the parameter of interest is now the number of cycles of a given fraction of a peak ground acceleration as a function of magnitude and distance from the source of an earthquake, rather than the peak ground acceleration (PGA) as a function of magnitude and distance.

Savy, Jean

1988-06-01

245

Breeding biology and natural history of the Slate-throated Whitestart in Venezuela  

USGS Publications Warehouse

We provide details on the breeding biology of the Slate-throated Whitestart (Myioborus miniatus) from 126 nests found during seven breeding seasons, 2002-2008, at Yacamb?? National Park, Venezuela. Nesting activity peaked in late April and May. Only the female built the nest and incubated the eggs. Males rarely visited the nest during these stages. Mean clutch size (2.1 ?? 0.04 eggs, n = 93) was the smallest recorded for the Slate-throated Whitestart. Incubation and nestling period lengths were 15.3 ?? 0.31 (n = 21) and 10.8 ?? 0.24 (n = 7) days, respectively. Attentiveness (% of time on the nest) during incubation (59 ?? 1.6%, n = 52) was similar to other tropical warblers and much lower than northern relatives. This caused a relatively low egg temperature (34.40 ?? 0.33u C, n = ?? nests, 20 days) compared with north temperate birds. Both parents fed nestlings and increased their provisioning rates with nestling age. Growth rate based on nestling mass (k = 0.521 ?? 0.015) was faster than for other tropical passerines but slower than northern relatives. Predation was the main cause of nesting failure and rate of predation increased with age of the nest. An estimated 15% of nests were successful based on an overall Mayfield daily predation rate of 0.053 ?? 0.007. This study confirms a strong latitudinal variation in life history traits of warblers. ?? 2010 by the Wilson Ornithological Society.

Ruggera, R. A.; Martin, T. E.

2010-01-01

246

Tectonic implications of Paleocene-Eocene Foreland Basin, Lake Maracaibo, Venezuela  

SciTech Connect

A compilation of industry geological and geophysical data indicates that Paleocene-Eocene clastic sedimentation in the Maracaibo basin records the first manifestation of Cenozoic foreland basin tectonics in northern South America. Isopach maps based on industry seismic data and well logs suggest that the Maracaibo foreland basin formed a 100 to 200 km wide elongate trough along the northeastern edge of the present-day Lake Maracaibo. The basin is asymmetric with a deep (7 km) northeastern margin adjacent to an exposed southwest-verging thrust belt mapped by previous workers. Isopach mapping of seven seismic units within the Eocene suggest a nor-northwest to southeast migration of the depocenter from Paleocene to Middle Eocene time at a rate of 0.6 cm/year. A similar style of foreland basin has been previously identified over a distance of 1000 Km from western central Venezuela to Trinidad. Eocene to Pliocene ages of foreland basin sedimentation in these areas suggest time transgressive, oblique collision of the Caribbean plate along the northern margin of South America. Comparison of the age of deformation along both the northern and southern edges of the pro-Caribbean plate yield reasonable estimates for the rate of relative motion of this small plate relative to the larger America plates.

Lugo, J. (Lagoven S.A., Caracas (Venezuela)); Mann, P. (Univ. of Texas, Austin (United States))

1993-02-01

247

Delta virus infection and severe hepatitis. An epidemic in the Yucpa Indians of Venezuela.  

PubMed

Over a 3-year period, 149 Yucpa Indians in Venezuela developed hepatitis; 34 persons died and at least 22 developed chronic hepatitis. Children and young adults were primarily affected, especially males. Serologic testing showed that hepatitis B virus infection was highly endemic in this population, but also that 65% of patients had hepatitis B virus surface antigen (HBsAg) during or after illness. Most patients had evidence of delta-agent superinfection; 86% of HBsAg-positive patients had delta antibody, and delta antigen was found in specimens taken during autopsies on 7 of 9 patients. Serologic data suggested that most infections were due to delta superinfection of hepatitis B carriers, and that more than 60% of these infections progressed to chronic disease. Delta agent infection, and particularly delta superinfection of hepatitis B carriers, appears to be an ominous occurrence that may develop in populations among whom hepatitis B virus infection is endemic, and who have no other risk factor for delta infection. PMID:6696355

Hadler, S C; De Monzon, M; Ponzetto, A; Anzola, E; Rivero, D; Mondolfi, A; Bracho, A; Francis, D P; Gerber, M A; Thung, S

1984-03-01

248

[Mosquito fauna (Diptera:Culicidae) from Falcon State, Venezuela. I. New records and current checklist].  

PubMed

A total of 16 new species records of Culicidae from Falcon State was collected at the "Juan Crisostomo Falcon National Park" (Sierra de San Luis), Natural Monument "Cerro Santa Ana", Coro, and La Vela. Species of Sabethini, Culicini and Toxorhynchitini Tribes were found in natural breeding sites (Phytotelmata), with special occurrence in plants belonging to Tillandsia, Vriesea, Guzmania, Aechmea (Bromelianceae), Heliconia (Heliconiaceae), Calathea (Marantaceae) and Colocasia (Araceae). Aedini and Mansonini were collected only as adults. A specie of Culex (Carrollia) was collected from an artificial container. The Culicidae species belong to 6 genera out of the 23 genera reported from Venezuela (Culex, Wyeomyia, Johnbelkinia, Aedes, Psorophora, Mansonia and Coquillettidia) and to 5 Tribes out of the 9 present in the country. The Aedini, Sabethini and Culicini Tribes were richer in species with 5, 4 and 4 species, respectively, than the Mansonini (2 species) and Toxorhynchitini (1 species) Tribes. We discuss some bioecological aspects regarding the 16 new-species records in Falcon State and give a checklist of the mosquito species previously reported in the literature. PMID:9239851

Navarro, J C; Bastidas, R J; Zavala, Y

1994-01-01

249

Political economy of petrodollars: oil and democracy in Venezuela (Volumes I and II)  

SciTech Connect

This thesis explores the impact of changes in the international petroleum economy upon the development strategy and political process of one oil-producing nation, Venezuela. It contends that sudden great wealth, like scarcity, can be a serious development curse, leading to policy decisions that provoke economic disruption and political decay. This ''paradox of plenty'' can best be explained by the interplay of an internationally-generated crisis of wealth with the skewed socio-economic arrangements and weak states characteristic of late developers. This interaction results in management overload and a subsequent decline in the problem-solving abilities of the state, making the effective utilization of petrodollar surpluses exceedingly difficult. An investigation of the political and economic consequences of the Perez Adminsitration's attempt to build a diversified industrial structure following the quadrupling of oil prices in 1973 illustrates this central theme. President Perez' ''project'' of accelerated modernization, designed to meet the competing demands of party and business interests, led to a contradictory development model which was both populist and entrepreneurial.

Karl, T.L.

1982-01-01

250

[Susceptibility of M. tuberculosis to antituberculosis drugs as determined by two methods, in Sucre state, Venezuela].  

PubMed

The objective of this study was to evaluate the resistance to isoniazid (INH), rifampicin (RIF), streptomycin (STR) and ethambutol (EMB), with the Canetti's proportions method (PM) and the nitrate reductase assay (NRA) of 59 clinical strains of Mycobacterium tuberculosis, isolated in the period of august 2005 to december 2006, in Sucre state, Venezuela. Primary and acquired drug resistance was 6.3% and 14.3%, respectively. Only one strain was found to be multidrug resistant (MDR). The overall agreement between the NRA and PM was 100% for INH, RIF and EMB, and 96% for STR. The time to obtain results was 10 to 14 days for the NRA, compared to 42 days for the PM. The NRA was easy to perform and therefore represents a useful tool for rapid and accurate determination of drug-resistant M. tuberculosis. The sequence of the rpoB gene of the RIF resistant strain demonstrated a never described mutation (change in the codon 456; TCG > CAG) in the hypervariable region of 81 base pairs where most of the mutations of the RIF resistant strains have been reported. Comparison of our results with those of the last resistance prevalence study carried out in the years 1998-1999, shows a decrease in the studied area. PMID:21365873

Mendoza, Rosmy; De Donato, Marcos; de Waard, Jacobus H; Takiff, Howard; Bello, Teresita; Chirinos, Gladys

2010-12-01

251

Patterns of Ant (Hymenoptera: Formicidae) Richness and Relative Abundance along an Aridity Gradient in Western Venezuela.  

PubMed

In xeric ecosystems, ant diversity response to aridity varies with rainfall magnitude and gradient extension. At a local scale and with low precipitation regimes, increased aridity leads to a reduction of species richness and an increased relative abundance for some ant species. In order to test this pattern in tropical environments, ant richness and relative abundance variation were evaluated along 35 km of an aridity gradient in the Araya Peninsula, state of Sucre, Venezuela. Three sampling stations comprising five transects each were set up. Pitfall traps and direct collecting from vegetation were assessed per transect. Overall, 52 species, 23 genera, and 7 subfamilies of ants were recorded in the peninsula. The total number of species and genera recorded by both sampling stations and transects decreased linearly with increasing aridity. Total relative abundance was highest in the most arid portion of the peninsula, with Crematogaster rochai (Forel) and Camponotus conspicuus zonatus (Emery) (Hymenoptera: Formicidae) being the numerically dominant species. Spatial and multivariate analyses revealed significant changes in ant composition every 11 km of distance, and showed a decrease of ant diversity with the increase of harsh conditions in the gradient. Here, we discuss how local geographic and topographic features of Araya originate the aridity gradient and so affect the microhabitat conditions for the ant fauna. PMID:23949745

Pérez-Sánchez, A J; Lattke, J E; Viloria, A L

2012-12-21

252

Salmonella on feces, hides and carcasses in beef slaughter facilities in Venezuela.  

PubMed

This study determined Salmonella prevalence at different stages during the slaughtering in three beef slaughter plants (A, B and C) located in the western region of Venezuela (Zulia and Lara states). Each facility was visited three times at monthly intervals, from the months October through December of 2006. Samples were collected from hides (n=80), fecal grabs (n=80) and carcasses (n=80) at the phases of pre-evisceration, after-evisceration and pre-cooler at three sampling sites on the animals (rump, flank and brisket). Salmonella prevalence was higher on hides (36.3%) than on feces (13.8%) (P<0.05). Differences among slaughter plants for overall Salmonella prevalence were observed (P=0.001; A: 3.5%, B: 11.1%, C: 4.4%). From the isolated strains, Salmonella enterica subspecies enterica ser. Saintpaul, Salmonella ser. Javiana and Salmonella ser. Weltevreden were identified. Cattle feces and hides might be considered as important sources of Salmonella for carcass contamination at different slaughter stages. The presence of potentially pathogenic Salmonella serotypes at the slaughtering stages is an evidence of the circulation of this pathogen in the food environment; its presence could increase consumers' risks of infection if proper food handling and preparation techniques are not followed. These data should serve as a baseline for future comparisons in Salmonella prevalence on beef carcasses to be used by the government and industry in order to establish preventive measures and to better address the risks of Salmonella contamination. PMID:23973832

Narváez-Bravo, Claudia; Rodas-González, Argenis; Fuenmayor, Yrimar; Flores-Rondon, Carolina; Carruyo, Gabriela; Moreno, Mireya; Perozo-Mena, Armindo; Hoet, Armando E

2013-07-17

253

Biostratigraphic sequence analysis of two Lower Miocene to Pliocene sections, Eastern Falcon, Northwestern Venezuela  

SciTech Connect

The eastern region of the Falcon Basin in northwestern Venezuela comprises a thick sedimentary sequence deposited from a deep marine bathyal to neritic environment, ranging in age from the Middle Eocene to the Pliocene. A detailed biostratigraphic study (foraminifera and calcareous nannoplankton) was carried out in two sedimentary sequences outcropping in Cumarebo and Piritu, adjacent areas of eastern Falcon, representing: platform, slope and basinal settings. The Cumarebo section is continuous in the studied interval, from the Middle Miocene to the Pliocene. The Piritu section is continuous from the Lower to the lower Upper Miocene, terminating unconformably beneath a thin interval of middle Pliocene platform sediments, indicating tectonism during the latest Miocene. The sequence stratigraphical interpretation was based on the biostratigraphic analysis of the benthic and planktonic fossils, facies distribution and sedimentological data. Systems tracts, sequence boundaries and maximum flooding surfaces from cycles TB2.4 to TB3.5 of the cycle chart were identified. In the Cumarebo section, the upper Middle and Upper Miocene is mostly composed of shales, with some turbiditic sands belonging to a LSW system tract. The upper most Miocene contains a thick carbonate buildup (HST), and it is overlain by a Pliocene section that shallows upward from upper slope to outer shelf depositional environments. In the basinal (Piritu) section, most of the sediments are deep-water shales belonging to a LSW system tract, with some turbiditic sands in the upper Lower Miocene. TST and HST sediments, with scattered carbonate buildups in the upper Middle Miocene were also identified.

Diaz De Gamero, M.L. (Universidad Central de Venezuela, Caracus (Venezuela)); Giffuni, G.; Castro Mora, M. (Lagoven S.A., Caracus (Venezuela))

1993-02-01

254

[Spatio-temporal variation of subtidal meiofauna in a sandy beach from Northeastern Venezuela].  

PubMed

Meiofauna organisms that play an important role in the trophic ecology of soft bottom benthos, have short life cycles and they respond quickly to disturbance and pollution. The present study shows the spatio-temporal variation ofsubtidal meiofauna (metazoans passing a 500im sieve but retained on meshes of 40-63micro m) in four shallow subtidal stations. Samples were taken in the sandy beach of San Luis, in the Northeastern coast of Venezuela, from October 2005 until September 2006. For this, three replicate sediment core samples (4.91cm2), were collected monthly to a depth of 10cm into the sediment, and preserved in 6% formalin stained with rose Bengal. Specimens of 14 meiofaunal groups (Foraminifera excluded) were collected, being the nematodes, ostracods and harpacticoid copepods the most abundant. Monthly density was comprised between 64 and 503ind./10cm2, and mean density of stations between 173 and 449ind./10cm2. There is a trend of low densities from October to February (end of the rainy season until the middle of the dry season). The San Luis beach control of the meiofaunal community is shared by climatic conditions and by the biology of the species found. The meiofauna mean density in San Luis beach (263ind./10cm2) was low when compared to other studies in tropical areas. PMID:23894963

Arana, Ildefonso Liñero; Ojeda, Sol; Amaro, María Elena

2013-03-01

255

The hydrocarbon habitat of northern South America: Colombia-Venezuela-Trinidad  

SciTech Connect

A prolific hydrocarbon province extends across the northern margin of South America from Colombia to east of Trinidad. Two key components are a world-class source rock, formed on a regional Late Cretaceous passive margin, and a complex tectonic setting in which a variety of structural and stratigraphic traps, reservoirs, seals and hydrocarbon kitchens have evolved through time. Convergence between the Farallon and Caribbean plates with South America culminated in the late Cretaceous-early Palaeogene with emplacement of Colombia`s Central Cordillera in the west and a nappe-foreland basin system in the north. Regional hydrocarbon generation probably occurred below associated basins. Subsequent oblique convergence between the Caribbean and South America, partitioned into strike-slip and compressional strain, generated an eastward migrating and ongoing uplift-foredeep (kitchen) system from central Venezuela to Trinidad. Similarly, oblique interaction of western Colombia with the Nazca Plate caused segmentation of the earlier orogen, northward extrusion of elements such as the Maracaibo Block, and eastward migration of uplift progressively dividing earlier kitchens into localized foredeeps.

James, K.H. [Conoco, Inc., Houston, TX (United States)

1996-08-01

256

Influence of Mesozoic age structure on Miocene tectonic development in NE Anzoategui, Eastern Venezuela Basin  

SciTech Connect

Structure within and surrounding the Quiamare-La Ceiba region, Eastern Venezuela Basin, is dominated by two major thrust fault systems. They were generated during Early-Middle Miocene time in response to oblique convergence of the Caribbean and South American plates. They are. respectively, the SE vergent NE-SW oriented Anaco fault system, and the SSE vergent ENE-WSW oriented Pirital fault system. The major structural feature associated with each fault system is a basement cored ramp anticline. New seismic data provides evidence that contributes to a better understanding of the sequence of tectonic development within and surrounding the Quiamare-La Ceiba region. Compressional structures in both the hanging wall and the footwall of the Pirital fault system appear to be inverted normal faults, that were previously active during Mesozoic time along the northern South America passive margin. A conjugate set of strike-slip faults is also present. They are oriented NNW-SSE, parallel to the Urica lineation, and SSW-NNE, respectively. A Mesozoic origin for these faults is suggested. Post-compressional relaxation during Plio-Pleistocene time resulted in the development of shallow, small scale normal faults. These normal faults appear to be localized by structural adjustments along the strike-slip fault sets. Existing oil and gas production within the Quiamare-La Ceiba region is from localized structural closures. Strike-slip faults dissect the prevailing structural grain, and may provide an additional hydrocarbon trapping mechanism.

Sadler, P.; White, S.

1996-08-01

257

A new species of Caligus (Copepoda, Siphonostomatoida) from the plankton of the Caribbean coast of Venezuela with a key to species  

PubMed Central

Abstract During a survey of the zooplankton community of Bahía Amuay, Venezuelan Caribbean, specimens of an undescribed species of Caligus Müller were collected. It resembles Caligus xystercus Cressey and Caligus ocyurus Cressey, both known only from the Caribbean Sea. The new species can be distinguished from these and other congeners by a combination of characters including the armature of legs 1 and 4, but mainly by its unique female genital complex. This is the first species of Caligus described from Venezuela. The species is described in full and a key to the species of the genus recorded in Venezuela is provided.

Suarez-Morales, Eduardo; Camisotti, Humberto; Martin, Alberto

2012-01-01

258

Characterization and Analysis of the PikD Regulatory Factor in the Pikromycin Biosynthetic Pathway of Streptomyces venezuelae  

PubMed Central

The Streptomyces venezuelae pikD gene from the pikromycin biosynthetic cluster was analyzed, and its deduced product (PikD) was found to have amino acid sequence homology with a small family of bacterial regulatory proteins. Database comparisons revealed two hypothetical domains, including an N-terminal triphosphate-binding domain and a C-terminal helix-turn-helix DNA-binding motif. Analysis of PikD was initiated by deletion of the corresponding gene (pikD) from the chromosome of S. venezuelae, resulting in complete loss of antibiotic production. Complementation by a plasmid carrying pikD restored macrolide biosynthesis, demonstrating that PikD is a positive regulator. Mutations were made in the predicted nucleotide triphosphate-binding domain, confirming the active-site amino acid residues of the Walker A and B motifs. Feeding of macrolide intermediates was carried out to gauge the points of operon control by PikD. Although the pikD mutant strain was unable to convert macrolactones (10-deoxymethynolide and narbonolide) to glycosylated products, macrolide intermediates (YC-17 and narbomycin) were hydroxylated with high efficiency. To study further the control of biosynthesis, presumed promoter regions from pik cluster loci were linked to the xylE reporter and placed in S. venezuelae wild-type and pikD mutant strains. This analysis demonstrated that PikD-mediated transcriptional regulation occurs at promoters controlling expression of pikRII, pikAI, and desI but not those controlling pikRI or pikC.

Wilson, Daniel J.; Xue, Yongquan; Reynolds, Kevin A.; Sherman, David H.

2001-01-01

259

Non-capsulated and capsulated Haemophilus influenzae in children with acute otitis media in Venezuela: a prospective epidemiological study  

PubMed Central

Background Non-typeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae are major causes of bacterial acute otitis media (AOM). Data regarding AOM are limited in Latin America. This is the first active surveillance in a private setting in Venezuela to characterize the bacterial etiology of AOM in children < 5 years of age. Methods Between December 2008 and December 2009, 91 AOM episodes (including sporadic, recurrent and treatment failures) were studied in 87 children enrolled into a medical center in Caracas, Venezuela. Middle ear fluid samples were collected either by tympanocentesis or spontaneous otorrhea swab sampling method. Standard laboratory and microbiological techniques were used to identify bacteria and test for antimicrobial resistance. The results were interpreted according to Clinical Laboratory Standards Institute (CLSI) 2009 for non-meningitis isolates. All statistical analyses were performed using SAS 9.1 and Microsoft Excel (for graphical purposes). Results Overall, bacteria were cultured from 69.2% (63 of the 91 episodes); at least one pathogen (S. pneumoniae, H. influenzae, S. pyogenes or M. catarrhalis) was cultured from 65.9% (60/91) of episodes. H. influenzae (55.5%; 35/63 episodes) and S. pneumoniae (34.9%; 22/63 episodes) were the most frequently reported bacteria. Among H. influenzae isolates, 62.9% (22/35 episodes) were non-capsulated (NTHi) and 31.4% (11/35 episodes) were capsulated including types d, a, c and f, across all age groups. Low antibiotic resistance for H. influenzae was observed to amoxicillin/ampicillin (5.7%; 2/35 samples). NTHi was isolated in four of the six H. influenzae positive samples (66.7%) from recurrent episodes. Conclusions We found H. influenzae and S. pneumoniae to be the main pathogens causing AOM in Venezuela. Pneumococcal conjugate vaccines with efficacy against these bacterial pathogens may have the potential to maximize protection against AOM.

2012-01-01

260

Voice, Video and Data Transmission over Electrical Power Supply Networks. PLC (Power Line Communications): A Last Mile Alternative for Venezuela  

Microsoft Academic Search

In general terms, the public telecommunication networks in Venezuela are conformed by Access, Transport and Core Networks.\\u000a \\u000a The locations where does not exist telecommunications services but there are users, generally exits electrical services, which\\u000a allows utilization of existing electrical systems as the access network.\\u000a \\u000a \\u000a \\u000a During the development of this research it was consulted documentation related to PLC implementations in Europe,

261

Geochronology of recent sediments from the Cariaco Trench (Venezuela) by Alpha Spectrometry of 210Pb (210Po).  

NASA Astrophysics Data System (ADS)

210Pb concentration in marine sediments of the Cariaco Trench (North-East of Venezuela) was measured through the analysis of 210Po alpha emissions, which can be assumed to be in secular equilibrium with 210Pb. The analysed sediment core has a length of 1.9 m. The results allowed to apply the CF:CS dating model (Constant Flux and Constant Supply). The sedimentation rate was estimated to be 0.25 cm/y. As far as we know this is the first ?- dating carried out in the country, performed with an alpha spectrometer recently funded by the IAEA.

Arriojas, A.; Barros, H.; Palacios, D.; Hurtado, S.; Villa, M.; Pérez, K.; Alfonso, J.; Sajo-Bohus, L.

2010-08-01

262

Geochronology of recent sediments from the Cariaco Trench (Venezuela) by Alpha Spectrometry of {sup 210}Pb ({sup 210}Po)  

SciTech Connect

210Pb concentration in marine sediments of the Cariaco Trench (North-East of Venezuela) was measured through the analysis of 210Po alpha emissions, which can be assumed to be in secular equilibrium with 210Pb. The analysed sediment core has a length of 1.9 m. The results allowed to apply the CF:CS dating model (Constant Flux and Constant Supply). The sedimentation rate was estimated to be 0.25 cm/y. As far as we know this is the first {alpha}- dating carried out in the country, performed with an alpha spectrometer recently funded by the IAEA.

Arriojas, A.; Barros, H.; Palacios, D.; Sajo-Bohus, L. [Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of); Hurtado, S.; Villa, M. [Centro de Investigacion, Tecnologia e Innovacion de la Universidad de Sevilla (Spain); Perez, K.; Alfonso, J. [Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas (Venezuela, Bolivarian Republic of)

2010-08-04

263

[Reproductive activity of Chelonia mydas (Testudines: Cheloniidae) in Isla de Aves, Venezuela (2001-2008)].  

PubMed

The second major nesting-site for green turtles in the Caribbean is Isla de Aves, an island protected as a wildlife refuge since 1972, located at 650km Northeast from La Guaira, Venezuela. In this island, the nesting population monitoring started in 1972 and in a more continuous way after 1978, when a Scientific-Naval Station was established and scientific observations started. Since historical data show that female captures had severely affected population levels in this island before 1978, this study aim to describe recent reproductive activities. For this, during the nesting seasons of 2001-2002 and 2005-2008, nesting females were measured and tagged using metal flipper tags. A total of 458 nights were sampled observing 5 154 female emergences, with a maximum of 53 in a single night. Non-observed emergences were calculated fitting the temporal distribution of observed emergences to a normal curve. Total emergences estimated varied from X=637.1+/-106.6 in 2001 to X =2 853+/-42.5 in 2008 (ANOVA F(6.5df)=60.37, p<0.0001). Internesting interval in the same season was estimated in X=10.71+/-1.32 days. Clutch frequency in a nesting season was calculated as X=1.71+/-1.6 times per female and season. Estimated number of nesting females per year varied from X=373+/-12.5 females in 2001 to X=l 669+/-56.1 females in 2008 (ANOVA F 55.6df)=89.42, p<0.0001); with a positive and significant trend (r=0.842, p=0.036). Results show that nesting females numbers are increasing. We suggest that the protection of the nesting area for more than 30 years, has contributed with this population increase. PMID:23894943

Vera, Vicente; Buitrago, Joaquín

2012-06-01

264

Sources of ?15N variability in sinking particulate nitrogen in the Cariaco Basin, Venezuela  

NASA Astrophysics Data System (ADS)

Ten years of monthly observations of the ?15N of sinking particulate nitrogen (?15N-PN (in ‰ versus atmospheric N2)=[(15N/14N)sample/(15N/14N)standard)-1]1000) in the Cariaco Basin, Venezuela, confirm that the basin's bottom sediments store information about nitrogen dynamics related to seasonal and interannual variability in regional surface ocean processes. During the upwelling period of the southern Caribbean Sea (February-April), the ?15N-PN is similar to that of the thermocline nitrate (˜3.5‰). This nitrate is imported into the Cariaco Basin with Subtropical Underwater (SUW), which wells up near the coast. Thus, particles generated by phytoplankton photosynthesis during this productive period bear a sub-tropical North Atlantic isotopic imprint of N2 fixation (low compared to the global average of nitrate ?15N?5‰). During the non-upwelling period when surface waters are stratified (September-November), the ?15N-PN is also 3.5-4.0‰, and reflects a mixture of local N2 fixation within the mixed layer, inputs of terrigenous organic matter and SUW nitrate consumption by phytoplankton below the mixed layer, which most likely exerts the strongest control on the ?15N-PN signal during this time. In the transition periods of May-July and December-January, the ?15N-PN increases to 4.5-6.5‰. This coincides with maxima of continental material fluxes (terrestrial PON ?15N is >6‰) into the Cariaco Basin. The ?15N signal in the sediments of the Cariaco Basin thus provides information about the relative strength of the local coastal upwelling, the relative input of continental material via river runoff, and local N2 fixation. The findings contribute to interpretations of the basin's paleoclimatic nitrogen cycle variations based on observations of the sedimentary ?15N record at this location.

Montes, Enrique; Thunell, Robert; Muller-Karger, Frank E.; Lorenzoni, Laura; Tappa, Eric; Troccoli, Luis; Astor, Yrene; Varela, Ramón

2013-09-01

265

Sub-B'' layering in the Southern Caribbean: The Aruba Gap and Venezuela Basin  

NASA Astrophysics Data System (ADS)

Multichannel seismic data in the Aruba Gap region near JOIDES/DSDP Site 153 verify the presence of a deep sub-B'' reflection. One multichannel seismic line trends NE-SW on and along the edge of Beata Ridge and passes within 1 km of Site 153, and another line runs N-S across the entire Aruba Gap with the drill site 4 km east from its northern end. Closely spaced velocity analyses indicate the presence of deep primary reflection events and enable calculation of interval velocities between the A''-B'' marker horizons. Deconvolved, true amplitude, normal incidence profiles sharply delineate the A''-B'' marker horizons and indicate the presence of the sub-B'' reflection event. On the NE-SW line, this deep reflector is best described as a ``diffuse'' discontinuous zone, relatively horizontal, lying about 0.8 seconds of two-way travel time below the B'' reflector, with an interval velocity of approximately 5.0 km/s between Horizon B'' and this reflection. The N-S line is more complex since the sub-B'' reflection event is masked by a strong internal multiple from the A''-B'' interval. In the central and western Venezuela Basin, deep primary reflections beneath Horizon B'' are also observed on the northern and western sides of what appears to be a major fault zone. This fault zone separates the smooth B'' and sub-B'' reflectors on the northern and western sides of this fault zone from what appears to be typical oceanic basement. The widespread presence of sub-B'' reflections yielding high interval velocities for the section between these events and Horizon B'' suggest that this material is probably igneous in origin.

Stoffa, Paul L.; Mauffret, A.; Truchan, M.; Buhl, Peter

1981-04-01

266

Mechanisms of Oryza sativa (Poaceae) resistance to Tagosodes orizicolus (Homoptera: Delphacidae) under greenhouse condition in Venezuela.  

PubMed

Tagosodes orizicolus is one of the main plagues of rice in tropical America causing two types of damages, the direct one, feeding and oviposition effect, and an indirect one, by the transmission of the "Rice hoja blanca virus". During 2006-2007 we carried out research under greenhouse conditions at Fundaci6n Danac, Venezuela, in order to determine the mechanisms of antixenosis, antibiosis and tolerance to T. orizicolus, which could be acting in commercial varieties and advanced lines of the rice genetic breeding programs of INIA and Fundaci6n Danac. The method of free feeding was used for the antixenosis evaluation, whereas the method of forced feeding was used for antibiosis evaluation (effect on survival and oviposition). Additionally, we used the indirect method based on biomass depression to estimate the tolerance. Some of the evaluated traits included: grade of damage, number of insects settling on rice plants, percentage of sogata mortality at the mature state, number of eggs in the leaf midrib and an index of tolerance. The results showed that rice genotypes possess different combinations of resistance mechanisms, as well as different grades of reactions. The susceptible control 'Bluebonnet 50' was consistently susceptible across experiments and the resistant control 'Makalioka' had high antixenosis and high antibiosis based on survival and oviposition. The rest of the genotypes presented lower or higher degrees of antixenosis and antibiosis for survival and oviposition. The genotype 'FD0241-M-17-6-1-1-1-1' was identified with possible tolerance to the direct damage of sogata. PMID:22458212

González, Alex; Labrín, Natalia; Alvarez, Rosa M; Jayaro, Yorman; Gamboa, Carlos; Reyes, Edicta; Barrientos, Venancio

2012-03-01

267

The role of seismic microzoning within the disaster prevention in Venezuela  

NASA Astrophysics Data System (ADS)

Due to the experience of the strong rainfalls which experienced great parts of Venezuela in early 2005, a national commission for risk management (CNGR) was created, that is composed by representatives from the Ministry of Interior and Justice, the Ministry of Environment, Defense Ministry, Infrastructure Ministry, Habitát and Housing Ministry and Science and Tecnology Ministry. The participation of the different ministries, which are represented by institutions related to hidrometeorological research and slope stability, amongst others, enables to focuss the risk management from anintegrated point of view. Within this commission, FUNVISIS, the official agency for seismological investigations, represents the Science and Tecnology Ministry and is responsible for the actions to be taken to reduce the seismic risk. A plan to reduce the seismic hazard and vulnerability, presented by FUNVISIS, was approved by the commission, in order to establish state policies to minimize the impact to the comunities in case of the ocurrence of an earthquake. Therein, seismic microzoning studies are addressed as the methodology to follow in order to reduce the seismic risk, which includes the evaluation of regional conditions (fault ocurrences, source characteristics, attenuation) as well as the knowledge of the local conditions (wave propagation, geological conditions, site effects). The interdisciplinary methods used within the microzoning studies (joint work done by geologists, geophysicists, civil engineers, arquitects, teachers) enable to address the results of the studies in away that they can be assimilated by the communities that live in the respective urban areas as well as by the local governments. Recommendations to local buiding codes as well as training of the communities take an important part within the projects.

Malave, G.

2007-05-01

268

Lessons in posttraumatic stress disorder from the past: Venezuela floods and Nairobi bombing.  

PubMed

Identification and treatment of posttraumatic stress disorder (PTSD) are important following a disaster. Insights into how these aims can be achieved may be obtained from previous disasters. This article describes mental health initiatives following the 1999 flooding in Vargas State, Venezuela, and the 1998 U.S. Embassy bombing in Nairobi, Kenya. Following the Vargas State floods, a specialist mental health center devoted to the diagnosis, treatment, and follow-up of PTSD was established. Awareness and acceptance of the clinic was promoted by media campaigns and community-based activities. After 18 months, approximately 5000 people had been screened, of whom 62% were diagnosed with PTSD and treated. Moreover, the clinic's activities had expanded to include treatment of other medical conditions and assistance with nonmedical needs. Following the Nairobi bombing, a mass media campaign was initiated to create awareness of PTSD symptoms and help victims come to terms with their experience. This campaign was found to be well received and helpful. In addition, counselors were trained to support people living or working close to the blast. These examples show that mental health initiatives are feasible after a disaster and highlight a number of issues: (1) The intervention should be tailored to the needs of the target population; (2) Communication should be simple and appropriate; (3) Community-based activities are valuable in promoting awareness and acceptance of mental health initiatives; (4) Reducing the stigma often associated with mental health problems is important; and (5) The mass media can be helpful in promoting awareness of mental health issues following major trauma. PMID:16602817

Carlos Otero, Juan; Njenga, Frank G

2006-01-01

269

Tectonic inheritance, crustal architecture, and contrasting structural styles in the Venezuela Andes  

NASA Astrophysics Data System (ADS)

Surface and subsurface data image contrasting structural styles for the two flanks of the Venezuela Andes. In the north, a flexural basin developed in Neogene times between the Andes and the Lake Maracaibo. North verging thrusts are mainly detached in the pre-Cretaceous substratum and form a deeply buried antiformal stack. Secondary décollement levels occur both in the Upper Cretaceous and Tertiary strata, accounting for the passive roof thrust of a conventional frontal triangle zone. In the south, the Barinas basin hardly compares with a flexural basin. It is largely dominated by both north and south verging basement-involving structures. Paleogene normal faults are locally inverted, and Caribbean nappes are frequently reactivated or refolded by younger oblique Neogene Andean structures. Seismic profiles in this area also attest to the strong Neogene structural inversion of Upper Jurassic-Lower Cretaceous grabens. Hercynian, or more likely Early Paleozoic structures account for local preexisting crustal heterogeneities, reactivated during both the Tethyan rifting and the Andean deformations. Two trans-Andean regional profiles have been balanced and constrained by an inversion of the gravimetric data. They imply a progressive deepening of the northern Moho and a south dipping subduction of the infracontinental lithospheric mantle of the Maracaibo block. The shortening for both sections averages 60 km. Palinspastic restorations assume a relative cylindricity for the deep crustal architecture of the Andes and minimize the possible effects of a progressive right-lateral escape of the Maracaibo block with respect to stable South America along the Bocono Fault. Strain partitioning during Neogene oblique convergence induced surficial thrust fronts parallel to the plate boundary, strike-slip motion in the allochthon along the Bocono Fault, and an asymmetric subduction (wedging) at depth.

Colleta, Bernard; Roure, François; De Toni, Bruno; Loureiro, Daniel; Passalacqua, Herminio; Gou, Yves

1997-10-01

270

Subsidence related horizontal earth movements in the Tia Juana field, State of Zulia, Venezuela  

SciTech Connect

Subsidence due to oil exploitation in the Bolivar Coast fields in western Venezuela has been monitored since 1926. Related horizontal earth movements have been measured by geodetic methods during the last 10 yr in the northern Tia Juana field area in and around the Ule tank farm and the GLP gas liquefaction plant. Damage to storage tanks and increasing appearance of fractures in the ground in the vicinity of the coastal dyke protection system warranted a detailed study. A surface geologic survey of the Ule area, based initially on aerophotographic interpretation of infrared photographs, flown, on a 1:5,000 scale, showed the area to be divided into blocks by several major faults. These faults were confirmed on the ground by visual inspection, shallow seismic refraction, geoelectric surveys and correlation of geotechnical borings. A geodetic survey of the area with a precision of 5 mm + 2 mm/km for distances, showed significant horizontal displacements of ground markers during an eight-year period. Accordingly, a measuring plan of high-precision (0.015 mm) electromechanic extensometer lines was designed for critical zones across known fault traces and fracture zones. A conceptual model integrates geodetic and extensometer measurements of horizontal movements in the Ule area with the geologic and neotectonic frame of subsurface faults, joining systems, and tensional surface cracks. Rates of Holocene postglacial isostatic adjustments and natural, pre-industry subsidence due to degassing of reservoirs determined by C{sup 14} radiocarbon dating, were used to calculate subsidence rates due to oil exploitation. It was found that the subsidence occurs in the area, not as previously mapped continuous function of compaction, but as discrete, fault and crack limited blocks, governed as much by reactivation of fault slippage as by subsurface compaction.

Scherer, W.F.; Pedroza, M.A. (Intevep, S.A., Caracas (Venezuela))

1990-05-01

271

Sources of ?15N variability in sinking particulate nitrogen in the Cariaco Basin, Venezuela  

NASA Astrophysics Data System (ADS)

Ten years of monthly observations of the ?15N of sinking particulate nitrogen (?15N–PN (in ‰ versus atmospheric N2)=[(15N/14N)sample/(15N/14N)standard)?1]1000) in the Cariaco Basin, Venezuela, confirm that the basin's bottom sediments store information about nitrogen dynamics related to seasonal and interannual variability in regional surface ocean processes. During the upwelling period of the southern Caribbean Sea (February–April), the ?15N–PN is similar to that of the thermocline nitrate (˜3.5‰). This nitrate is imported into the Cariaco Basin with Subtropical Underwater (SUW), which wells up near the coast. Thus, particles generated by phytoplankton photosynthesis during this productive period bear a sub-tropical North Atlantic isotopic imprint of N2 fixation (low compared to the global average of nitrate ?15N?5‰). During the non-upwelling period when surface waters are stratified (September–November), the ?15N–PN is also 3.5–4.0‰, and reflects a mixture of local N2 fixation within the mixed layer, inputs of terrigenous organic matter and SUW nitrate consumption by phytoplankton below the mixed layer, which most likely exerts the strongest control on the ?15N–PN signal during this time. In the transition periods of May–July and December–January, the ?15N–PN increases to 4.5–6.5‰. This coincides with maxima of continental material fluxes (terrestrial PON ?15N is >6‰) into the Cariaco Basin. The ?15N signal in the sediments of the Cariaco Basin thus provides information about the relative strength of the local coastal upwelling, the relative input of continental material via river runoff, and local N2 fixation. The findings contribute to interpretations of the basin's paleoclimatic nitrogen cycle variations based on observations of the sedimentary ?15N record at this location.

Montes, Enrique; Thunell, Robert; Muller-Karger, Frank E.; Lorenzoni, Laura; Tappa, Eric; Troccoli, Luis; Astor, Yrene; Varela, Ramón

2013-09-01

272

Microseismicity, tectonics and seismic potential in southern Caribbean and northern Venezuela  

NASA Astrophysics Data System (ADS)

Approximately one thousand microearthquakes with body-wave magnitude mb have been located in northern Venezuela and the southern Caribbean region (9-12° N; 64-70° W) since the installation in 1980 of the Venezuelan Seismological Array, together with forty events of mb 4, one of them with surface-wave magnitude Ms 6. Focal depths are in the range of 0 to 400 km long subparallel fault zones: San Sebastián fault zone (SSF), 20 km north of Caracas along the coast; and La Victoria fault zone (LVF), 25 km south of the city. They are clearly delineated by the microseismicity. New composite focal mechanism solutions (CFMS) along these faults show right-lateral strike-slip (RLSS) motion on nearly E-W oriented fault planes. NW-striking subsidiary active faults occur in the region and intercept the two main E-W fault zones. These interceptions show high levels of microearthquake activity and seismic moment release when compared to other portions of both, the main and subsidiary faults. New CFMS at those fault crossing sites show NW-striking RLSS motion and normal faulting, in an en-echelon-like structural behavior. Geological data and quantitative comparisons with other transcurrent plate boundaries in the world suggest that the rate of plate motion in this area is on the order of 20 mm/y. Several moderate and large shocks have occurred along the SSF and LVF since 1640, including an Ms 7.6 event in 1900 on SSF. Although the region may be relatively far from a repeat of this earthquake, seismicity data indicate that strong shocks could take place along segments of the seismically active faults identified in this study.

Pérez, Omar J.; Sanz, Carlos; Lagos, Gabriela

273

3D Spectral Element Method Simulations Of The Seismic Response of Caracas (Venezuela) Basin  

NASA Astrophysics Data System (ADS)

We present here 3D numerical simulations of the response of the Caracas (Venezuela) valley up to 5 Hz for different scenarios of plane wave excitation based on the regional seismicity. Attention is focused on the effects of the 3D basin geometry and of the adjacent regional topography. The simulations are performed using Spectral Element method (SEM) together with an unstructured hexahedral mesh discretization and perfectly matched layers (PML). These simulations show 3D amplification phenomena associated with complex wave reflexion, diffraction and focalisation patterns linked to the geometry of the basin. Time and frequency analysis reveal some interesting features both in terms of amplification and energy residence in the basin. The low frequency amplification pattern is mainly controlled by the early response of the basin to the incident plane wave while the high frequency amplification patterns result mainly from late arrivals where complex 3D wave diffraction phenomena are dominating and the memory of the initial excitation is lost. Interestingly enough, it is shown that H/V method correctly predict the low frequency amplification pattern when apply to the late part of the recorded seismograms. The complex high frequency amplification pattern is shown to be associated with surface wave generation at, and propagation from, sharp edges of the basin. Importance of 3D phenomena is assessed by comparison with simple 2D simulations. Significant differences in terms of time of residence, energy and amplification levels point out the interest of complete 3D modeling. In conclusions some of the limitations associated with the use of unstructured hexahedral meshes will be adressed. Despite the use of unstructured meshing tool, modeling the geometry of geological basins remain a complex and time consuming task. Possible extensions using more elaborate techniques like non conforming domain decomposition will be also discussed in conclusion.

Delavaud, E.; Vilotte, J.; Festa, G.; Cupillard, P.

2007-12-01

274

Distribution and mobility of mercury in soils of a gold mining region, Cuyuni river basin, Venezuela.  

PubMed

An extensive and remote gold mining region located in the East of Venezuela has been studied with the aim of assessing the distribution and mobility of mercury in soil and the level of Hg pollution at artisanal gold mining sites. To do so, soils and pond sediments were sampled at sites not subject to anthropological influence, as well as in areas affected by gold mining activities. Total Hg in regionally distributed soils ranged between 0.02 mg kg(-1) and 0.40 mg kg(-1), with a median value of 0.11 mg kg(-1), which is slightly higher than soil Hg worldwide, possibly indicating long-term atmospheric input or more recent local atmospheric input, in addition to minor lithogenic sources. A reference Hg concentration of 0.33 mg kg(-1) is proposed for the detection of mining affected soils in this region. Critical total Hg concentrations were found in the surrounding soils of pollutant sources, such as milling-amalgamation sites, where soil Hg contents ranged from 0.16 mg kg(-1) to 542 mg kg(-1) with an average of 26.89 mg kg(-1), which also showed high levels of elemental Hg, but quite low soluble+exchangeable Hg fraction (0.02-4.90 mg kg(-1)), suggesting low Hg soil mobility and bioavailability, as confirmed by soil column leaching tests. The vertical distribution of Hg through the soil profiles, as well as variations in soil Hg contents with distance from the pollution source, and Hg in pond mining sediments were also analysed. PMID:21215510

Santos-Francés, F; García-Sánchez, A; Alonso-Rojo, P; Contreras, F; Adams, M

2011-01-06

275

[Pollination and pollinators in the vegetation of the coastal plain of Paraguaná, Falcón State, Venezuela].  

PubMed

Pollination systems and plant-pollinator dynamics were studied for 51 plant species according to life form, vegetation type, and flowering phenology in the Paraguaná peninsula, Venezuela. A total of 43 species of floral visitors were recorded from which only 33 (76.7%) were effective pollinators and ten only visitors. Pollinator fauna consisted only of insects. Six pollinating agent classes were identified in the area of study. Pollinating bees were the most important class (35.1%), followed by butterflies (24.3%) and flies (13.5%). This trend was similar for the psamophilous and mangrove vegetation, but pollinating wasps were the third in importance in the littoral vegetation. Temporal distribution of pollinating agent classes showed a peak during the flowering peak, and during the lowest level of rainfall in the locality. Pollination systems were mostly polyphilous (62.7%) followed by monophilous (27.4%), and oligophilous species (7.8%). This trend was found to be similar for the different vegetation types and life forms. In a similar way, pollinator agents were mainly polytropic (60.4%), followed by monotropic (24.6%) and oligotropic species (14.8%). Plant species/pollinator species ratio was close to one for all vegetation types in the Paraguaná peninsula. Besides, the average number of pollinator species per plant species was 2.2, and the average number of plant species pollinated per insect species was 2.7. Plant species/pollinator species ratio and the average values of pollinator and plant species indicate a diffuse and symmetric relation between pollinator and plant species. These results are discussed in the context of the dynamics of pollination. PMID:14976781

Lemus-Jiménez, Luis José; Ramírez, Nelson

2003-01-01

276

[Reproductive phenology of three vegetation types from a coastal plain of Paraguana Penninsula, Venezuela].  

PubMed

Reproductive phenology of 51 plant species was evaluated according to life form and vegetation types in a coastal plain of the Paraguaná Peninsula, Estado Falcón, Venezuela. Plant species distribution according to three vegetation types (herbaceous littoral, herbaceous psamophil, and mangrove area) was determined. Life form frequency was different according to vegetation type. Herbaceous littoral and herbaceous psamophil vegetation were dominated by herbaceous species; woody species were mostly frequent in the mangrove vegetation. Phenological data revealed that 14 (27.5%) plant species flower and fruit year-round; 23 (45.1%) plant species flower and fruit at the beginning of the wet season; seven (13.7%) plant species flower at the end of wet season, and seven (13.7%) more flower at the beginning of the dry season. Flowsring and fruiting phenology showed similar frequency distribution during the year; reproductive phenology was independent of life forms. Flowering and fruiting peaks occurred during the rainy season and the beginning of the dry season for trees and perennial herbs, and from one to three months later for shrubs and annual herbs. The lowest proportion of flowering and fruiting occurred before rain increase for all life forms. Flowering and fruiting phenologies were similar for the three vegetation types evaluated: flowering peak occurred during the lowest value of precipitation, three to four months after precipitation peak, and fruiting peak occurred four months later from the precipitation peak. These results suggest that flowering and fruiting phenology were not affected by life form and vegetation types. The peaks of flowering and fruiting during the lowest values of precipitation may be considered as a slow and late response to the precipitation maximum, and to the proximity between maximum and minimum of precipitation. PMID:12945492

Lemus-Jiménez, Luis José; Ramírez, Nelson

2002-01-01

277

Venezuela-MEM/USA-DOE Fossil Energy Report IV-11: Supporting technology for enhanced oil recovery - EOR thermal processes  

SciTech Connect

This report contains the results of efforts under the six tasks of the Tenth Amendment anti Extension of Annex IV, Enhanced Oil Recovery Thermal Processes of the Venezuela/USA Energy Agreement. This report is presented in sections (for each of the six Tasks) and each section contains one or more reports that were prepared to describe the results of the effort under each of the Tasks. A statement of each Task, taken from the Agreement Between Project Managers, is presented on the first page of each section. The Tasks are numbered 68 through 73. The first through tenth report on research performed under Annex IV Venezuela MEM/USA-DOE Fossil Energy Report Number IV-1, IV-2, IV-3, IV-4, IV-5, IV-6, IV-7, IV-8, IV-9, IV-10 contain the results of the first 67 Tasks. These reports are dated April 1983, August 1984, March 1986, July 1987, November 1988, December 1989, October 1991, February 1993, March 1995, and December 1997, respectively.

Venezuela

2000-04-06

278

Deep-seated gravitational slope deformations along the active Boconó Fault in the central portion of the Mérida Andes, western Venezuela  

Microsoft Academic Search

Two very large deep-seated gravitational slope deformations in the highlands of the Mérida Andes, Venezuela, are herein described: the Mucubají Pass and Cerro La Camacha. These slope movements have slid in post-Last Glacial Maximum times. In addition, both landslides are in very close association with the active Boconó Fault trace. The Cerro La Camacha (Camacha Range) landslide is fault bounded

Franck A. Audemard; Christian Beck; Eduardo Carrillo

2010-01-01

279

Cambios en el uso de tabaco y factores relacionados en estudiantes del sexto al noveno grado, Estado Lara, Venezuela, años 2000 y 2003  

Microsoft Academic Search

The Global Youth Tobacco Survey (GYTS) is a school-based surveillance system. In Lara State, Venezuela, it was conducted by a coalition of or- ganizations. The instrument includes: attitudes, knowledge, behaviors, exposure to environmen- tal tobacco smoke, mass media, and marketing. Participation was 85.7% in 2000 and 79.3% in 2003. Comparing prevalence (%) from 2000 to 2003: \\

Ricardo Granero; Magda Sánchez

2006-01-01

280

Marcadores biológicos de estrés oxidativo. Distribución por edad y sexo de las concentraciones basales de MDA, NO y ácido úrico en niños y adolescentes de Maracaibo-Venezuela  

Microsoft Academic Search

Despite recognition of the detrimental effects of malondial- dehyde (MDA), nitric oxide (NO) and uric acid on oxidative stress, this hypothesis has not yet been tested in healthy chil- dren and adolescents. The objective of the present study was to describe the behavior of these parameters, in a sample of healthy children and adolescents from Maracaibo, Zulia State, Venezuela. After

Souki A; Cano C; Mengual E; García D; Torres D; Almarza J; León L; Chávez Z; Molero E; Medina M; Félix Gómez

2007-01-01

281

ESTUDIO PRELIMINAR DE LA INFLUENCIA DE LA COSTRA MICROBIÓTICA EN LOS SUELOS DE QUÍBOR, ESTADO LARA, VENEZUELA, MEDIANTE MICROANÁLISIS DE RAYOS-X (EDS)  

Microsoft Academic Search

A microbiotic crust, consisting photosynthetic organisms, develops in about the first 3mm of surface in the locality of Quíbor Lara state, Venezuela. The crust is constituted by algae, cyanobacteria, mosses (bryophytes) and lichens. The objective of this investigation is the determination of the chemical elements that compose the matrix of the soil with microbiotic crust in the interphases morphological soil-structure

282

A new species of the lycopsid Gilboaphyton Arnold from the Devonian of Venezuela and New York State, with a revision of the closely related genus Archaeosigillaria Kidston  

Microsoft Academic Search

A new species of the small, probably herbaceous lycopsid Gilboaphyton Arnold is based on new material from the Devonian of western Venezuela. The excellently preserved compressions allow the following characteristics to be established: (1) the presence below the leaf bases of large oval areas of parenchymatous tissue within a toughened outer stem tissue (outer cortex) which could be infilled with

Christopher M. Berry; Dianne Edwards

1997-01-01

283

Avances en el diagnóstico del cáncer de la mama. Importancia de la pesquisa y diagnóstico precoz. Reflexiones sobre el problema en Venezuela  

Microsoft Academic Search

Early diagnosis of breast cancer is a main progress in modern medicine. We resume advances in clinic, risk factors, radiology, pathology, in situ carcinoma and sub clinic lesions. Results of screening trials using mammography in others countries, decreasing mortality, pros and cons. We analyse the problem in Venezuela and call attention over the great number of advanced lesions seen in

José Antonio; Ravelo Celis

2001-01-01

284

Feasibility Study for the Modernization of the Public Health Care System in Venezuela. Audit and Evaluation of Equipment and Installations Component. Volume 3. Technical Specifications. Final Report.  

National Technical Information Service (NTIS)

The report, conducted by Booz-Allen, was funded by the U.S. Trade and Development Agency. This report concerns the modernization of Venezuela's health care system, Proyecto Salud. The main objectives of Proyecto Salud are: to modernize the health care del...

1997-01-01

285

Analysis of the Performance of the M-6 Area of the Tia Juana Field, Venezuela, under Primary, Steam-Soak, and Steamdrive Conditions  

Microsoft Academic Search

This paper deals with the reservoir performance of the M-6 Project Area in the south-east of the Tia Juana field. The field is one of the four heavy oil fields located along the eastern shore of Lake Maracaibo in Venezuela, collectively known as the Bolivar Coast fields. Since the early 1930's the area covered by these fields subsides, an observation

Fernando Puig; Leendert Schenk; S. A. Maraven

1984-01-01

286

Coinfection with Three Ehrlichia Species in Dogs from Thailand and Venezuela with Emphasis on Consideration of 16S Ribosomal DNA Secondary Structure  

Microsoft Academic Search

As part of a larger study to investigate tick-borne infections in dogs from Thailand and Venezuela, docu- mentation of coinfection with three Ehrlichia species in two dogs, one from each country, became the focus of the present study. Although neither dog had clinical signs attributable to ehrlichiosis, both dogs were anemic and neutropenic and the Thai dog was thrombocytopenic. Genus-

JIRAPORN SUKSAWAT; CHRISTIAN PITULLE; CRUZ ARRAGA-ALVARADO; KARINA MADRIGAL; SUSAN I. HANCOCK; EDWARD B. BREITSCHWERDT

287

PREFERENCIA DE AVES DE CAZA DE LOS YE'KWANA EN LA RESERVA FORESTAL EL CAURA, EDO. BOLÍVAR REPÚBLICA BOLIVARIANA DE VENEZUELA  

Microsoft Academic Search

An advance of the wild birds hunted by the Yékwana natives of the communities of Mouth of Nichare, Icutú, Fortuna and Maripa was made more; these communities are located in the Forest Reserve the Caura (48,040 km2) in the State Bolivar to the South of Venezuela. Between the wild birds more hunted by the Yékwana we have at Crax alector,

LUGO M. Diosey

288

New insights into the tectonic evolution of the Boconó Fault, Mérida Andes, Venezuela  

NASA Astrophysics Data System (ADS)

The Boconó fault is a major right-lateral strike-slip fault that cuts along strike the Mérida Andes in Venezuela. The uplift of this mountain range started in the Miocene as a consequence of the relative oblique convergence between two lithospheric units named the Maracaibo block to the northwest and the Guyana shield to the southeast. Deformation in the Mérida Andes is partitioned between a strike-slip component along the Boconó fault and shortening perpendicular to the belt. Distinctive features define the Boconó fault: it is shifted southward relative to the chain axis and it does not have a continuous and linear trace but is composed of several fault segments of different orientations striking N35°E to N65°E. Quaternary fault strike-slip motion has been evidenced by various independent studies. However, onset of the strike-slip motion, fault offset and geometry at depth remains a matter of debate. Our work, based on morphostructural analyses of satellite and digital elevation model imagery, provides new data on both the geometry and the tectonic evolution of this major structure. We argue that the Boconó fault affects only the upper crust and connects at depth to a décollement. Consequently, it can not be considered as a plate boundary. The Boconó fault does however form the boundary between two different tectonic areas in the central part of the Mérida Andes as revealed by the earthquake focal mechanisms. South of the Boconó fault, the focal mechanisms are mainly compressional and reverse oblique-slip in agreement with NW SE shortening in the foothills. North of the Boconó fault, extensional and strike-slip deformation dominates. Microtectonic measurements collected in the central part of the Boconó fault are characterized by polyphased tectonics. The dextral shearing along the fault is superimposed to reverse oblique-slip to reverse motion, showing that initiation of transcurrent movement is more likely to have occurred after a certain amount of shortening. The present day strain partitioning along the Mérida Andes seems to be younger than the rise of the chain and coeval with the initiation of right-lateral shearing along the Boconó fault, which would have then initiated in the Pliocene. The Mérida Andes can be therefore considered as a case study of the kinematic evolution of a major strike-slip fault.

Backé, G.

2006-12-01

289

Oblique Collision of the Leeward Antilles, Offshore Venezuela: Linking Onshore and Offshore Data from BOLIVAR  

NASA Astrophysics Data System (ADS)

The kinematic history of the Leeward Antilles (offshore Venezuela) can be characterized with the integration of onshore outcrop data and offshore seismic reflection data. Deformation structures and seismic interpretation show that oblique convergence and wrench tectonics have controlled the diachronous deformation identified along the Caribbean - South America plate boundary. Field studies of structural features in outcrop indicate one generation of ductile deformation (D1) structures and three generations of brittle deformation (F1 - F3) structures. The earliest deformation (D1/F1) began ~ 110 Ma with oblique convergence between the Caribbean plate and South American plate. The second generation of deformation (F2) structures initiated in the Eocene with the extensive development of strike-slip fault systems along the diffuse plate boundary and the onset of wrench tectonics within a large-scale releasing bend. The most recent deformation (F3) has been observed in the west since the Miocene where continued dextral strike-slip motion has led to the development of a major restraining bend between the Caribbean plate transform fault and the Oca - San Sebastian - El Pilar fault system. Deformation since the late Cretaceous has been accompanied by a total of 135° clockwise rotation. Interpretation of 2D marine reflection data indicates similar onshore and offshore deformation trends. Seismic lines that approximately parallel the coastline (NW-SE striking) show syndepositional normal faulting during F1/F2 and thrust faulting associated with F3. On seismic lines striking NNE-SSW, we interpret inversion of F2 normal faults with recent F3 deformation. We also observe both normal and thrust faults related to F3. The thick sequence of recent basin sedimentation (Miocene - Recent), interpreted from the seismic data, supports the ongoing uplift and erosion of the islands; as suggested by fluid inclusion analysis. Overall, there appears to be a strong correlation between onshore micro- and mesoscopic deformational structures and offshore macro-scale structural features seen in the reflection data. The agreement of features supports our regional deformation and rotation model along the Caribbean - South America obliquely convergent plate boundary.

Beardsley, A. G.; Avé Lallemant, H. G.; Levander, A.; Clark, S. A.

2006-12-01

290

Some autecological characteristics of early to late successional tree species in Venezuela  

NASA Astrophysics Data System (ADS)

The breadth of the continuum concept of strategy with respect to succession was tested on 21 tree and shrub species common in either unlogged or logged stands, respectively, in the Forest Reserve of Caparo, Venezuela, by examining morphological, physiological and population characteristics. Based on a preliminary abundance analysis, `early', `mid' and `late' successional species as well as `generalists' were distinguished. Early successional species, i.e. Ochroma lagopus, Heliocarpus popayanensis and Cecropia peltata were similar in many autecological aspects, e.g. monolayered leaf arrangement, orthotropic architectural models, no adaptive reiteration, clumped distribution, but differed in gap association and distribution along a drainage gradient. Mid-successional species established themselves both in large and small gaps (> 300 m[sup2 ]; 80-300 m[sup2 ]) and showed a clumped to regular distribution pattern in logged areas; they exhibited more diverse crown and leaf characteristics than early successional species. Late successional species established themselves only in small gaps and understorey, and showed a regular spatial pattern in undisturbed areas. All late successional species displayed architectural models with plagiotropic lateral axes and showed a multilayered leaf arrangement. Adaptive reiteration was a common feature of late successional species which could be further subdivided into large, medium-sized and small trees, indicating different light requirements at maturity. Generalists were common treelet and shrub species in both disturbed and undisturbed sites where they are also capable of completing their life cycle. The light compensation point (LCP) of an individual plant was strongly influenced by its crown illuminance. Large late successional species showed the widest range of LCP values, reflecting the increasing light availability with increasing height in mature forest. On the basis of many autecological characteristics, it was found (i) that there is in fact a continuum of species strategies with respect to succession even among early and mid-successional species and (ii) that the latter group of species showed the widest breadth of autecological traits, reflecting the heterogeneous environment in which they establish and mature.

Kammesheidt, Ludwig

2000-01-01

291

Regional tectonics, sequence stratigraphy and reservoir properties of Eocene clastic sedimentation, Maracaibo Basin, Venezuela  

NASA Astrophysics Data System (ADS)

The Maracaibo basin of Venezuela is one of the most prolific hydrocarbon basins in the world. During the Paleogene, oblique collision between the Caribbean and South American plates produced a 4-km-thick wedge of clastic sediments, where over 40 billion barrels of hydrocarbons have been produced. Previous studies in the Eocene interval are focused either at a large regional scale or a field-size reservoir scale. Integration between both scales of observation has not been previously done, and, as a consequence, the effect of regional tectonics is not considered in the small-scale stratigraphic record. The aim of this dissertation is to study the interplay of tectonic and stratigraphic variables that controlled the Eocene sedimentation in the Maracaibo basin, and to establish a geologic model that incorporates data from a regional to reservoir scale. Interpretation of 2-D and 3-D seismic data in the central and eastern Maracaibo basin reveals two major tectonic features formed during Paleogene collision between the Caribbean and the South American plates: (1) a late Paleocene-early Eocene foreland basin; and (2) a middle-late Eocene lateral ramp fault. The lateral ramp fault forms a paleogeographic facies boundary separating a less faulted and folded shelf area to the west from a fold-thrust belt to the east. In the Eocene Maracaibo shelf area, intraplate deformation occurs by NNE-striking left-lateral faulting with pull-apart basins localized at fault stepovers. Three-dimensional seismic time slice interpretation of more than 2000 km2 of 3-D seismic data allows mapping of the Icotea pull-apart basin. Extension of the Icotea pull-apart basin is localized on pre-existing NW-SE-striking normal faults, formed by Paleocene-Eocene plate flexure during the foreland basin period. Detailed sequence stratigraphic interpretation of the central Maracaibo basin was carried out using 330 wells and 3-D visualization methods that combined well and 3-D seismic data techniques providing greater vertical and lateral resolution (pseudo-seismic). These data reveal that Eocene clastic sedimentation is controlled by tectonic subsidence and to a lesser degree by changes in sediment supply and eustasy. Hydrocarbon reservoirs of the central Maracaibo basin are concentrated in distributary channels and tidal sand bar facies on structural highs produced by strike-slip motion of N-NE-striking faults. Depositional environments and fluid content of Eocene reservoirs are inferred from cross sections based on closely spaced well logs.

Escalona, Alejandro

292

Breeding biology of the golden-faced Tyrannulet (Zimmerius chrysops) in venezuela  

USGS Publications Warehouse

We present the first detailed information on the breeding biology of the Golden-faced Tyrannulet (Zimmerius chrysops). Information was gathered from 96 nests in Yacamb National Park, Venezuela during the 2002 to 2008 breeding seasons. The enclosed nest was similar to descriptions of nests of other species in the genus. Eggs were laid on alternate days with mean (?? SE) clutch size of 1.98 ?? 0.02 (n 45) and fresh weight of 1.616 ?? 0.020 g (n 48). Only the female incubated and the incubation period averaged 16.9 ?? 0.3 days (n 10). Nest attentiveness ( time on the nest) averaged 66.0 ?? 1.6 (n 40) and increased from early to mid- and late-incubation. Incubation behavior yielded an average 24-hr egg temperature of 34.88 ?? 0.45?? C (n 7 nests, 43 days). The nestling growth rate constant for body mass (k 0.285 ?? 0.011) was slow even for tropical tyrannids. The nestling period for nests where exact hatch and fledging days were observed ranged from 17 to 19 days with an average of 18.0 ?? 0. 2 days (n 9). Both females and males fed nestlings at a rate that increased over the nestling period with a mean of 4.41 ?? 0.65 trips/hr (n 10) during days 1 and 2 after hatching, and 14.93 ?? 2.36 trips/hr (n 6) at pin-break (days 1011). Daily predation rates were similar in egg-laying (0.052 ?? 0.025; n 76.5 exposure days) and incubation periods (0.068 ?? 0.010; n 575.5 exposure days), but were lower during the nestling period (0.039 ?? 0.010; n 377.0 exposure days). The total daily predation rate (0.057 ?? 0.007; n 989.0 exposure days) indicated only 12 of nests were successful. These breeding biology parameters for Z. chrysops differ substantially from other tyrant-flycatchers and temperate species, further highlighting the diversity within the Tyrannidae. ?? 2010 by the Wilson Ornithological Society.

Goulding, W.; Martin, T. E.

2010-01-01

293

Sound production and hearing in the blue cracker butterfly Hamadryas feronia (Lepidoptera, nymphalidae) from Venezuela.  

PubMed

Certain species of Hamadryas butterflies are known to use sounds during interactions with conspecifics. We have observed the behaviour associated with sound production and report on the acoustic characteristics of these sounds and on the anatomy and physiology of the hearing organ in one species, Hamadryas feronia, from Venezuela. Our observations confirm previous reports that males of this species will take flight from their tree perch when they detect a passing conspecific (male or female) and, during the chase, produce clicking sounds. Our analyses of both hand-held males and those flying in the field show that the sounds are short (approximately 0.5 s) trains of intense (approximately 80-100 dB SPL at 10 cm) and brief (2-3 ms) double-component clicks, exhibiting a broad frequency spectrum with a peak energy around 13-15 kHz. Our preliminary results on the mechanism of sound production showed that males can produce clicks using only one wing, thus contradicting a previous hypothesis that it is a percussive mechanism. The organ of hearing is believed to be Vogel's organ, which is located at the base of the forewing subcostal and cubital veins. Vogel's organ consists of a thinned region of exoskeleton (the tympanum) bordered by a rigid chitinous ring; associated with its inner surface are three chordotonal sensory organs and enlarged tracheae. The largest chordotonal organ attaches to a sclerite positioned near the center of the eardrum and possesses more than 110 scolopidial units. The two smaller organs attach to the perimeter of the membrane. Extracellular recordings from the nerve branch innervating the largest chordotonal organ confirm auditory sensitivity with a threshold of 68 dB SPL at the best frequency of 1.75 kHz. Hence, the clicks with peak energy around 14 kHz are acoustically mismatched to the best frequencies of the ear. However, the clicks are broad-banded and even at 1-2 kHz, far from the peak frequency, the energy is sufficient such that the butterflies can easily hear each other at the close distances at which they interact (less than 30 cm). In H. feronia, Vogel's organ meets the anatomical and functional criteria for being recognized as a typical insect tympanal ear. PMID:11076733

Yack, J E; Otero, L D; Dawson, J W; Surlykke, A; Fullard, J H

2000-12-01

294

REDES DE VIGILANCIA SISMICA Y VIGILANCIA DE TSUNAMIS Seismic and tsunami monitoring networks  

Microsoft Academic Search

The impact of the natural phenomena on the world-wide population is every more important due to the growth of the population; in addition this one is concentrated in coastal zones, so the tsunami risk in- creases. In the Pacific ring of fire they operate international, national and regional tsunami alert sys- tems. In this chapter the evolution and the operation

Sara Figueras Vila

295

LA VULNERABILITA' SISMICA DEGLI EDIFICI ESISTENTI IN C.A. PROGETTATI PER SOLI CARICHI VERTICALI  

Microsoft Academic Search

SUMMARY The buildings erected in Italy in the '70es and '80es, designed only for gravity loads, have been here analyzed. Due to the fact that the seismic classification of Italy is recently changed in significant way, procedures for evaluating the capacity of this kind of existing buildings to withstand earthquakes (vulnerability) and for increasing this capacity are strongly requested. In

BRUNO CALDERONI; Napoli EMILIA A. CORDASCO; PIETRO LENZA

2006-01-01

296

[Population status of insects of Plecoptera order in Sierra Nevada National Park in Venezuela and its implications for conservation planning].  

PubMed

Longitudinal distribution of Plecoptera species were examined along the Sierra Nevada National Park in the Andean region of Merida State, Venezuela. PNSN is one of the largest protected areas and consists of two major sub-basins. Quantitative samples were collected in 7 river tributaries along the PNSN from February to May of 2009, and a total of 135 individuals and 4 species of the genus Anacroneuria were collected. Only three rivers (Nuestra Señora, La Picón y Corcovada) found the presence of stoneflies, the principal component analysis show that the characterization of habitat, current velocity, dissolved oxygen and the absence of human disturbance sources of influence in a suitable habitat for populations. Stoneflies are endangered or have become extinct throughout much of its range due to human activities. Conservation plans must be implemented urgently, in order to avoid recreational areas and/or economic in vicinity thereof. PMID:21250479

Gamboa, Maribet

2010-12-01

297

[Antibodies against Venezuelan equine encephalitis in the human population of the Mara district of the state of Zulia, Venezuela].  

PubMed

Antibodies against Venezuelan Equine Encephalitis Virus (VEEV) were studied in the human population of Mara District, Zulia State, Venezuela. Two hundred thirty nine blood samples were taken from the towns of San Rafael de Mara, Santa Cruz de Mara, La Sierrita-4 Bocas, Carrasquero, Isla de San Carlos e Isla de Toas, during june, july and september, 1988. Donors samples were classified by age, sex and serological titres. Eighty nine were less than 15 years old (37.2%) and 150, over 15 years old (62.7%). From the 239 samples, 224 were negative (93.7%) and 15 positive (6.3%). Our results indicate that must of the population from the studied towns were negative for VEEV antibodies and being exposed to the disease. PMID:2101637

Ryder, S; Bracho, D

1990-01-01

298

Role of extensional tectonics in exhumation of eclogites and blueschists in an oblique subduction setting: Northeastern Venezuela  

NASA Astrophysics Data System (ADS)

Eclogites and blueschists in northeastern Venezuela belong to a mid- to Late Cretaceous subduction complex-fore-arc terrane related to right-oblique subduction of the Proto-Caribbean plate beneath the Farallon plate along the Leeward Antilles volcanic island arc. These rocks were metamorphosed at high pressures and subsequently underwent retrogradation at decreasing pressures but at constant or slightly increasing temperatures. They underwent five phases of deformation: three synmetamorphic and two postmetamorphic. The major principal extensions (X axes) of each of the three synmetamorphic deformations are subparallel to the volcanic arc. The extension parallel to the arc and the associated exhumation and uplift of the subduction complex-fore-arc terrane may have resulted primarily from an increase of the arc-parallel displacement rate of this terrane caused by an increase of obliquity of plate convergence.

Avé Lallemant, Hans G.; Guth, Lawrence R.

1990-10-01

299

Large-scale shrimp farming in coastal wetlands of Venezuela, South America: Causes and consequences of land-use conflicts  

NASA Astrophysics Data System (ADS)

In Venezuela, large-scale shrimp farming began in the 1980s. By 1987, the Ministry of Environment and Natural Resources (MARNR) had received 14 proposals for approval. A developer illegally started the construction of ponds at the Píritu Lagoon in the State of Anzoátegui before the authorization process was completed. This action triggered a land-use conflict. This study identifies the causes for public protest and determines the consequences of this conflict for land-use management. The results show that public protest was based on the impacts of the partial construction of ponds. These impacts were related to direct removal of wetlands, interruption of natural patterns of surface flows, and alteration of feeding grounds of some bird species with migratory status. Consequences were identified in relation to the role that nongovernmental organizations (NGOs) play in land-use conflicts and the actions that MARNR could take in the future to prevent and solve similar situations.

Sebastiani, Mirady; González, Sara Elena; Castillo, María Mercedes; Alvizu, Pablo; Oliveira, María Albertina; Pérez, Jorge; Quilici, Antonio; Rada, Martín; Yáber, María Carolina; Lentino, Miguel

1994-09-01

300

[Floristic and physiognomic characteristics of disturbed thorny xerophytic scrubland in Punta de Piedras, Miranda Municipality, Zulia State, Venezuela].  

PubMed

We determined the floristic and physiognomic aspects of disturbed thorny xerophytic scrubland in Punta de Piedras, Miranda Municipality, Zulia State, Venezuela. Botanical sampling was done twice monthly (November 2005-June 2006), in both rainy and dry seasons, for a total of 16 samples. The sampling was done in 10 vegetation patches, in an average area of 718,2 +/- 706,24 m2, and adjacent graminoid floristic components were identified using three 400 m2 (20 x 20 m) plots, divided into 4 subplots (20 x 5 m2) and in these, were delimited 12 subplots (1 x 1 m2). In addition, human paths were carried out in order to identify other species plant. Thorny xerophytic scrubland showed human disturbances e.g. periodic fires, solid wastes, roads and human settlements and coastal semiarid thorny scrubland characteristics, similar to another Venezuelan localities. Forty-five species, in 22 families were identified, and the Poaceae (6), Mimosaceae (4), Boraginaceae (3), Cactaceae (3), Caesalpinaceae (3), Euphorbiaceae (3) and Fabaceae (3) presented the highest number of species. Human disturbances probably favor the appearance of vegetation patches and secondary grassland formations. In the last, Aristida venesuelae, Aristida pittieri y Portulaca pilosa showed the highest relative abundances and frequencies values with a summatory of 49,38% and 46,86%, respectively, while in the patches there were observed two layer: an herbaceous layer (less than 1 m high) as well as a bush-tree layer (2.63 +/- 1.37 m high), comprised mostly of Opuntia wentiana, Piptadenia flava and Jatropha gossypifolia with relative abundances of 32,82, 15,60 and 15,14%, respectively. The thorny xerophytic scrubland in Punta de Piedras presents a low number of species; however, the physiognomic characteristics are similar to other undisturbed thorny xerophytic scrublands in Venezuela. PMID:19637706

Vera, Antonio; Martínez, Maritza; Ayala, Yin; Montes, Sadieth; González, Anderson

301

Trypanosoma cruzi III from armadillos (Dasypus novemcinctus novemcinctus) from Northeastern Venezuela and its biological behavior in murine model. Risk of emergency of Chagas' disease.  

PubMed

Trypanosoma cruzi, etiological agent of Chagas' disease, was isolated from armadillos (Dasypus novemcinctus novemcinctus) captured in rural communities Northeastern Venezuela from Nueva Esparta State (no endemic for Chagas' disease), Monagas and Anzoátegui States (endemics). The isolates, genetically typed by PCR-RFLP as belonging to the TcIII DTU, have demonstrated in murine model heterogenic parasitemia, mortality and histotropism with marked parasitism in cardiac, skeletal, and smooth myocytes that showed correlation with lymphobasophilic inflammatory infiltrates. Our finding of T. cruzi infected armadillos in Isla Margarita (Nueva Esparta State), together with reports of triatomine vectors in this region, the accentuated synanthropy of armadillos, intense economic activity, migration due to tourism and the lack of environmental education programs all of them represent risks that could cause the emergence of Chagas' disease in this area. This is the first report of the TcIII DTU in Northeastern Venezuela, thus widening the geographic distribution of this DTU. PMID:22902748

Morocoima, Antonio; Carrasco, Hernán J; Boadas, Johanna; Chique, José David; Herrera, Leidi; Urdaneta-Morales, Servio

2012-08-10

302

Trypanosoma cruzi genotyping supports a common source of infection in a school-related oral outbreak of acute Chagas disease in Venezuela.  

PubMed

SUMMARY Trypanosoma cruzi I, a discrete typing unit (DTU) found in human infections in Venezuela and other countries of the northern region of South America and in Central America, has been recently classified into five intra-DTU genotypes (Ia, Ib, Ic, Id, Ie) based on sequence polymorphisms found in the spliced leader intergenic region. In this paper we report the genotype identification of T. cruzi human isolates from one outbreak of acute orally acquired Chagas disease that occurred in a non-endemic region of Venezuela and from T. cruzi triatomine and rat isolates captured at a guava juice preparation site which was identified as the presumptive source of infection. The genotyping of all these isolates as TcId supports the view of a common source of infection in this oral Chagas disease outbreak through the ingestion of guava juice. Implications for clinical manifestations and dynamics of transmission cycles are discussed. PMID:23544849

Díaz-Bello, Z; Thomas, M C; López, M C; Zavala-Jaspe, R; Noya, O; DE Noya, B Alarcón; Abate, T

2013-04-01

303

Characterization of the Mineral Phosphate-Solubilizing Activity of Pantoea aglomerans MMB051 Isolated from an Iron-Rich Soil in Southeastern Venezuela (Bolívar State)  

Microsoft Academic Search

The mineral phosphate-solubilizing (MPS) activity of a Pantoea agglomerans strain, namely MMB051, isolated from an iron-rich, acidic soil near Ciudad Piar (Bolívar State, Venezuela), was characterized\\u000a on a chemically defined medium (NBRIP). Various insoluble inorganic phosphates, including tri-calcium phosphate [Ca3(PO4)2], iron phosphate (FePO4), aluminum phosphate (AlPO4), and Rock Phosphate (RP) were tested as sole sources of P for bacterial growth.

Miguel Sulbarán; Elizabeth Pérez; María M. Ball; Alí Bahsas; Luis Andrés Yarzábal

2009-01-01

304

Eocene Upper-B reservoirs of the Bolivar Coastal Field, Venezuela - a classic stratigraphic trap with a strongly preferential reservoir orientation  

Microsoft Academic Search

Eocene Upper-B reservoirs of Lake Maracaibo, Venezuela are textbook examples of truncated, overlapped, and sealed stratigraphic traps. They have produced an appreciable part of the more than 10 billion barrels of oil produced from the Lagunillas Area of the Bolivar Coastal Field. In these fields, correlation of Upper-B reservoirs has always been very difficult-so difficult that detailed geological description was

D. C. Swanson; J. Salazar

1993-01-01

305

Snake venomics and antivenomics of Bothrops colombiensis, a medically important pitviper of the Bothrops atrox-asper complex endemic to Venezuela: Contributing to its taxonomy and snakebite management  

Microsoft Academic Search

The taxonomic status of the medically important pitviper of the Bothrops atrox-asper complex endemic to Venezuela, which has been classified as Bothrops colombiensis, remains incertae cedis. To help resolving this question, the venom proteome of B. colombiensis was characterized by reverse-phase HPLC fractionation followed by analysis of each chromatographic fraction by SDS-PAGE, N-terminal sequencing, MALDI-TOF mass fingerprinting, and collision-induced dissociation

Juan J. Calvete; Adolfo Borges; Álvaro Segura; Marietta Flores-Díaz; Alberto Alape-Girón; José María Gutiérrez; Nardy Diez; Leonardo De Sousa; Demetrio Kiriakos; Eladio Sánchez; José G. Faks; José Escolano; Libia Sanz

2009-01-01

306

Interpretacion y Biomecanica. Hoja de consejos de PEPNet (Interpreting and Biomechanics. PEPNet Tipsheet)  

ERIC Educational Resources Information Center

|This publication, written in Spanish, describes cumulative trauma disorder (CTD), which refers to a collection of disorders associated with nerves, muscles, tendons, bones, and the neurovascular (nerves and related blood vessels) system. CTD symptoms may involve the neck, back, shoulders, arms, wrists, or hands. Interpreters with CTD may…

DeGroote, Bill; Morrison, Carolyn

2010-01-01

307

Surface exploration geochemistry: Numerical data processing of near surface hydrocarbon gases and application in the Llanos Basin, Venezuela  

SciTech Connect

Traditional exploration techniques in near surface gas surveys usually apply hydrocarbon (HC) gas concentrations and HC gas ratios to extract information relevant to exploration. Although gas surveys are sometimes used to define exploration fairways or to evaluate prospects, nearsurface data are often misleading and prone to misinterpretation. This is largely the result of a poor understanding of the origin, distribution and fate of HC gases in near surface regime. We report new numerical techniques based on unmixing algorithms that allow for the discrimination and determination of individual gas sources in near surface sediments. Results clearly show a variety of HC gas sources that build up complex gas compositions and gas associations in this shallow environment. The bulk of non-seepage related HC gases is discriminated from a (usually) small fraction of shallow HC gases related to seepage. Model calculations are used to systematically search for a defined seepage signal in these gas data sets. This technique, termed GEL (Geochemical Exploration Lead), is described and exploration examples are provided from the Llanos area, Venezuela. Drilling results on some anomalies show commercial deep oil reservoirs with very low gas/oil - ratio. The prognosis of the well status clearly points to an increased success ratio when GEL data are incorporated into seismic/geologic information.

Von Der Dick, H. [ChemTerra Exploration, Roetgen (Germany); Callejon-Gimenez, A. [Corpoven, Puerto La Cruz (Venezuela); Bosman, D. [ChemTerra International Consulting Ltd., Calgary (Canada)

1996-08-01

308

[Viability and activity of the lactic bacteria (Streptococcus salivarius ssp thermophilus y Lactobacillus delbrueckii ssp bulgaricus) del yogurt en Venezuela].  

PubMed

National and international legislations have agreed that the population of lactic bacteria in yogurt must be viable and not less than 10(6) ufc/g. In Venezuela, during last years, observations indicate that the number of viable cells in some commercial samples show high variations, as low levels. This research attempted to find the origin of this problem in the local industry. For this purpose 105 commercial samples were analyzed during their shelf life and 32 samples of yogurt prepared in the laboratory following the flow diagram of the local industry. The different conditions of freeze dried lactic culture, were also analyzed. These samples were evaluated for viable cell count of lactic bacteria and possible variations of pH and acidity. The absence or low number of lactic bacteria detected in some commercial samples is due to the use of inadequate working cultures that show imbalanced proportions of the two microorganisms, besides a low count below 106 ufc/g. The succesive propagation and storage time of mother culture, and the overacidification of the product, produce subletal injury to the microbial cells of the yogurt starter culture. The data indicate that manufacturing practices significantly affect the survival of the lactic flora. PMID:11510428

Briceño, A G; Martínez, R; García, K

2001-01-01

309

The relationship between mud volcanoes, petroleum migration and accretionary prisms: Lessons from the Caucasus, the Australian margin and Venezuela  

SciTech Connect

Mud volcanoes have been widely documented in areas of overpressure where explosive expansion of trapped methane has occurred during argillokinesis. In an area with high sedimentation rate, such as the Gulf of Mexico, there may be no time for fine-grained sediment to de-water before being covered by impermeable material. In an accretionary wedge this process is complicated by overthrusting of off-scraped material which increases the overburden pressure and provides many more avenues for the migration of fluids through the system. In some cases, such as is seen in the Caribbean, the fluids may escape directly to the surface (or seabottom) through high permeability beds. When this happens there may be no diapirism. In other cases, such as in Venezuela, the forearc may be the site of rapid, laterally-derived, sedimentation, and fluids from the overthrusted rocks may be forced to escape through several kilometers of recent deltaic sediments. Since these fluids may include petroleum, this has obvious exploration potential. If there are no suitable reservoir rocks, such as in Timor, there may be no commercial accumulations. However, many giant fields are associated, world-wide, with mud volcanoes, such as those in Azerbaijan.

Ware, P. [Unocal, Sugar Land, TX (United States)

1996-08-01

310

Venezuela-MEM/USA-DOE Fossil Energy Report XIII-1, Supporting Technology for Enhanced Oil Recovery, Microbial EOR  

SciTech Connect

The results from Annex XIII of the Cooperative Agreement between the United States Department of Energy (DOE) and the Ministry of Energy and Mines of the Republic of Venezuela (MEMV) have been documented and published with many researchers involved. Integrate comprehensive research programs in the area of Microbial Enhanced Oil Recovery (MEOR) ranged from feasibility laboratory studies to full-scale multi-well field pilots. The objective, to cooperate in a technical exchange of ideas and information was fully met throughout the life of the Annex. Information has been exchanged between the two countries through published reports and technical meetings between experts in both country's research communities. The meetings occurred every two years in locations coincident with the International MEOR conferences & workshops sponsored by DOE (June 1990, University of Oklahoma, September 1992, Brookhaven, September 1995, National Institute of Petroleum and Energy Research). Reports and publications produced during these years are listed in Appendix B. Several Annex managers have guided the exchange through the years. They included Luis Vierma, Jose Luis Zirritt, representing MEMV and E. B. Nuckols, Edith Allison, and Rhonda Lindsey, representing the U.S. DOE. Funding for this area of research remained steady for a few years but decreased in recent years. Because both countries have reduced research programs in this area, future exchanges on this topic will occur through ANNEX XV. Informal networks established between researchers through the years should continue to function between individuals in the two countries.

Ziritt, Jose Luis

1999-11-03

311

Epidemiology of the Cnidarian Physalia physalis stings attended at a health care center in beaches of Adicora, Venezuela.  

PubMed

Stings caused by jellyfish and jellyfish-like colonies are common all around the world, with serious manifestations and occasional deaths reported in some countries. Between December 2006 and 2007, epidemiological, clinical and treatment aspects of stings caused by the Portuguese man-of-war (Physalia physalis) in 59 patients consulting the ambulatory emergency in Adicora, Falcon State, Venezuela, were studied. Most of the stings occurred in males (59%) preschool and school-aged children (49%), visitors from other areas of the country (92%) during holidays when bathing or diving at the beach (97%). Injuries presented linear erythematous plaques at the point of contact with the animal, located in several anatomical sites. Most clinical manifestations observed were: intense burning pain, urticaria, erythema and inflammation (100%), as well dyspnea with laryngeal edema and fever (19%). Patients were treated with topical drugs, including antihistamine and antipyretic drugs, but also with systemic hydrocortisone. P. physalis stings in Adicora appeared to have a seasonal pattern, with systemic complications potentially life-threatening. Thus, epidemiological surveillance program is recommended, particularly in travelers. PMID:23067562

Cazorla-Perfetti, Dalmiro J; Loyo, Jesus; Lugo, Lusneida; Acosta, María E; Morales, Pedro; Haddad, Vidal; Rodriguez-Morales, Alfonso J

2012-10-13

312

Tomato chlorotic leaf distortion virus, a new bipartite begomovirus infecting Solanum lycopersicum and Capsicum chinense in Venezuela.  

PubMed

Virus isolate T217L was obtained from a diseased tomato (Solanum lycopersicum) plant showing leaf deformation and chlorotic mottle symptoms near Maracaibo in the state of Zulia, Venezuela. Full-length DNA-A and DNA-B molecules of T217L were cloned and sequenced. The genome organization of T217L was identical to the bipartite genomes of other begomoviruses described from the Americas. Characteristic disease symptoms were reproduced in S. lycopersicum and Capsicum annum plants inoculated using the cloned viral DNA-A and DNA-B components, confirming disease aetiology. A sequence analysis of DNA-A showed that the T217L isolate has the highest sequence identity (84%) with sida yellow mosaic Yucatan virus (SiYMYuV), sida golden mosaic Honduras virus (SiGMHV) and bean dwarf mosaic virus (BDMV) isolates. This is less than the 89% identity in the DNA-A component that has been defined as the threshold value for the demarcation of species in the genus Begomovirus. The molecular data show that isolate T217L belongs to a novel tentative begomovirus species, for which the name tomato chlorotic leaf distortion virus is proposed. TCLDV was also detected in symptomatic C. chinense plants growing near the T217L-infected plant. PMID:21853328

Zambrano, Karla; Geraud-Pouey, Francis; Chirinos, Doris; Romay, Gustavo; Marys, Edgloris

2011-08-19

313

Snuff synergy: preparation, use and pharmacology of yopo and Banisteriopsis caapi among the Piaroa of southern Venezuela.  

PubMed

Current understanding of the preparation and use of yopo, a hallucinogenic snuff made from the ground seeds of the Anadenanthera peregrina tree, has departed little from the accounts of scientists and travelers made over a century ago. Schultes and others have made refinements to these early accounts. While several scholars have drawn attention to the fact that little ethnographic work has been conducted to assess the ethnobotanical diversity and cultural framework of the snuff hallucinogen complex, few subsequent studies deal with botanical variations in preparation and use. This article contrasts historical accounts of yopo preparation with ethnographic data I have recently collected among the Piaroa of southern Venezuela to demonstrate one way in which yopo preparation and use deviates from the basic model established by Humboldt, Spruce and Safford. Piaroa shamans include B. caapi cuttings in the preparation of yopo and consume doses of B. caapi prior to snuff inhalation concomitant with the strength of visions desired for particular tasks. I argue that the combined use of yopo and B. caapi by Piaroa shamans is pharmacologically and ethnobotanically significant, and substantiates claims of the use of admixtures in snuff; further ethnographic investigation of the snuff hallucinogen complex is necessary. PMID:12422937

Rodd, Robin

314

Seroprevalence to bovine virus diarrhoea virus and other viruses of the bovine respiratory complex in Venezuela (Apure State).  

PubMed

Six hundred and fifteen serum samples obtained from cows in five districts of Apure State, Venezuela, were tested by ELISA for antibodies to bovine virus diarrhoea virus (BVDV). The same samples were also ELISA-tested for antibodies to bovine herpesvirus type 1 (BHV-1) and bovine respiratory syncytial virus (BRSV). Additionally, the haemagglutination-inhibition (HI) test was used for detecting antibodies to parainfluenza virus type 3 (PIV-3). Overall, seroprevalence to BVDV was 36+/-7% (SE); seroprevalence varied by district (19-42%). BHV-1 seroprevalence was 67+/-4%; variation by district was similar to that of BVDV. However, the first 80 serum samples tested by BHV-1 ELISA all had a strong background reaction with the control antigen. Therefore, these sera were adsorbed to a homogenate of non-infected bovine kidney cell line (MDBK) and retested by ELISA. The non-specific reactivity was significantly reduced (p<0.001 by Wilcoxon's signed-rank test). Compared to the virus-neutralisation (VN) test, the adsorbed BHV-1 ELISA showed 94% agreement and gave a kappa value of 0.84, indicating that the adsorption did not interfere with test accuracy. Seroprevalence against BRSV was 85+/-3%, and showed differences across districts. Most of the cows (94+/-2%) were seropositive to PIV-3, and there were no significant differences among districts. PMID:10530426

Obando, R C; Hidalgo, M; Merza, M; Montoya, A; Klingeborn, B; Moreno-López, J

1999-08-23

315

Magnitude of fluid movement and rates of cementation associated with reverse faults Examples from the Maracaibo basin, Venezuela  

NASA Astrophysics Data System (ADS)

Magnitude of vertical fluid movement and rates of quartz cementation were studied in three cored intervals where reverse faults cut the Eocene Misoa Fm in the Maracaibo basin, Venezuela. The faults are flower type structures, with slips up to 500 meters, generated by an Eocene inversion of Cretaceous-Paleocene normal displacements. The fault zones extend 2.5 meters away from the slip surface and are characterized by extensive quartz and chert precipitation associated with microfractures and cataclasis. Kinetic modeling of quartz precipitation suggests that the rates of microfracture annealing may have been initially up to 0.25 moles/C, lasting approximately 1 my after faulting started (37.5 mya) and subsequently decreasing during uplifting to less than 0.05 moles/C. Kinetic modeling suggests that quartz cementation along these reverse faults may have occurred in short periods of time and at approximately the same or lower rates than intervals away from faults. Minimum vertical distance of fluid flow along one fault zone was calculated with two different approaches. The first method divides the thermal gradient present during faulting (obtained through a thermal reconstruction of the area) by a difference between the host rock maximum burial temperature and fault cements temperatures (obtained from fluid inclusions). The second method integrates an average-weight function of the thermal gradient along the unknown depth. Both methods suggest that hot fluids, present during cementation, ascended a minimum of 450 to 800 meter along the fault zone.

Perez, R. J.; Boles, J. R.

2002-12-01

316

Breeding biology of the Three-striped warbler in Venezuela: A contrast between tropical and temperate parulids  

USGS Publications Warehouse

We document reproductive life history traits of the Three-striped Warbler (Basileuterus tristriatus) from 146 nests in Venezuela and compare our results to data from the literature for other tropical and temperate parulid species. Mean (?? SE) clutch size was 1.96 ?? 0.03 eggs (n = 96) and fresh egg mass was 2.09 ?? 0.02 g. The incubation period was 15.8 ?? 0.2 days (n = 23) and the nestling period was 10.5 ?? 0.3 days (n = 12). Males did not incubate and rarely provided food for females during incubation. Females had 57 ?? 2% (n = 49) nest attentiveness (% of time on the nest incubating), which caused egg temperature to commonly become cold relative to development. Both adults fed nestlings and feeding rates increased with nestling age. The growth rate constant for nestlings based on mass was K 0.490, which is slower than for north temperate warblers. Predation was the primary source of nest failure and only 22% of nests were successful based on a Mayfield daily predation rate of 0.048 ?? 0.006. Our literature review indicates parulids differ strongly in life histories between temperate and tropical/subtropical sites with species in the tropics having, on average, smaller clutches, longer incubation periods, lower nest attentiveness, longer off-bouts, and longer nestling periods. ?? 2009 by the Wilson Ornithological Society.

Cox, W. A.; Martin, T. E.

2009-01-01

317

Structure of the Cordillera de la Costa Belt, North-Central Venezuela: Implications for plate tectronic models  

SciTech Connect

Preliminary results of an on-going study of the Cordillera de la Costa belt between Puerto Cabello and Choroni, north-central Venezuela, indicate that the deformational history is far more complicated than expected from simple plate-tectonic models. The Cordillera de la Costa belt consists of oceanic rocks (e.g., serpentinites, amphibilites, with lenses of eclogite and blueschist) intimately intermixed with metamorphosed continental margin deposits (e.g., mica and graphite schist, quartzite, marble). Locally, large granitic (basement ) complexes of Lower Paleozoic age are included as well. In late Cretaceous time, the entire belt was involved in four synmetamorphic deformations phases (D[sub 1a] to D[sub 1d]); the first (D[sub 1a]) occurred at depths of at 35-40 km and the later ones at successively shallower depths. This deformation occurred in a subduction zone, related to right-oblique convergence of the Farallon and Atlantic plates. The most penetrative structures resulted from (all in present coordinates) north-south contraction and east-west dextral simple shear (D[sub 1b]). During an Early Tertiary ( ) event (D[sub 2]), the belt was emplaced southward onto the South American continental margin. Subsequent deformational structures (D[sub 3]) resulted in cross folds and faults (with small pull-apart basins) which are consistent with the eastward passage of the Caribbean past the South American plate.

Ave Lallemant, H.G.; Sisson, V.B.; Wright, J.E. (Rice Univ., Houston, TX (United States))

1993-02-01

318

Mesozoic-Early Paleogene Paleogeography of Venezuela/Trinidad and its implications for Caribbean/South America plate interaction  

SciTech Connect

We present paleogeographic reconstruction illustrating Jurassic-Early Cretaceous passive margin development along northern South America, followed by Late Cretaceous-Middle Eocene convergence between the Caribbean and South America plates. The maps support the model of in-situ origin of the Caribbean Plate. To construct the map's information from northern allochthonous units was combined with that from autochthonous units in the south. Allochthons comprise olistostromes, within upper Cretaceous-lower Paleogene flysch deposits, and upper Jurassic-lower Cretaceous metasediments in the Caribbean Mountains. In addition, northward tectonic escape of the Maracaibo Block and shortening resulting from plate collision were restored. The Late Cretaceous-Middle Eocene climax of Caribbean-South America plate collision was coeval from western Venezuela to Trinidad. Shortening juxtaposed rocks of disparate origins. However, the association of oceanic/volcanic elements with shelf deposits shows that the former were related to opening of the Caribbean and development of the Mesozoic passive margin of northern South America rather than originating in the Pacific. Since the late Eocene, plate interaction has been eastward migrating, dextral relative movement.

James, K.H.; Rigby, S.M.

1993-02-01

319

New methymycin derivatives of Streptomyces venezuelae ATCC 15439 and their inhibitory effects on human T cell proliferation mediated by PMA/ionomycin.  

PubMed

Two new methymycin derivatives, 3'-demethylmethymycin (1) and 3'-demethyldeoxymethymycin (2), together with seven known ones (3-9), were obtained from the strain Streptomyces venezuelae ATCC 15439. Their structures were determined on the basis of IR, MS, 1D and 2D NMR data. In addition, the inhibitory effects of all the compounds on human T cell proliferation mediated by PMA/ionomycin were evaluated. The data suggested for the first time that methymycin derivatives have potential anti-inflammatory activity. PMID:23054713

Ding, Rong; Tang, Jinshan; Gao, Hao; Li, Ting; Zhou, Hua; Liu, Liang; Yao, Xin-Sheng

2012-10-09

320

Venezuelines A-G, new phenoxazine-based alkaloids and aminophenols from Streptomyces venezuelae and the regulation of gene target Nur77.  

PubMed

Five new phenoxazine-based alkaloids venezuelines A-E (1-5) and two new aminophenols venezuelines F-G (6-7), as well as three known analogues exfoliazone, chandrananimycin D and carboxyexfoliazone were isolated from the fermentation broth of the marine-derived bacterium Streptomyces venezuelae. The structures of new compounds were determined on the basis of extensive spectroscopic analysis. The cytotoxic activity of these compounds against a panel of tumor cell lines were tested, while the regulation of gene target Nur77 of 2 and exfoliazone (8) were evaluated. PMID:23164710

Ren, Jinwei; Liu, Dong; Tian, Li; Wei, Yangye; Proksch, Peter; Zeng, Jinzhang; Lin, Wenhan

2012-10-30

321

A new baseline for fascioliasis in Venezuela: lymnaeid vectors ascertained by DNA sequencing and analysis of their relationships with human and animal infection  

PubMed Central

Background Human and animal fascioliasis poses serious public health problems in South America. In Venezuela, livestock infection represents an important veterinary problem whereas there appear to be few human cases reported, most of which are passively detected in health centres. However, results of recent surveys suggest that the situation may be underestimated in particular areas. To obtain a baseline for future fascioliasis assessment, studies were undertaken by means of rDNA ITS-2 and ITS-1 and mtDNA cox1 sequencing to clarify the specific status of Venezuelan lymnaeids, their geographical distribution and fascioliasis transmission capacity, by comparison with other American countries and other continents. Results Results obtained completely change the lymnaeid scenario known so far. The relatively rich lymnaeid fauna of Venezuela has been proven to include (i) Lymnaea meridensis and L. neotropica as the only native members, (ii) L. cubensis and Pseudosuccinea columella introduced from the Caribbean area, and (iii) Galba truncatula and L. schirazensis introduced from the Old World. The absence of representatives of the stagnicoline and Radix groups is remarkable. Four species are fascioliasis vectors: G. truncatula, L. cubensis and L. neotropica, which have the capacity to give rise to human endemic areas, and P. columella, which is a source of animal infection and is responsible for the spread of disease. Vector capacity in the apparently highland endemic L. meridensis is to be confimed, although may be expected given its phylogenetic relationships. Similarly as elsewhere, the non-transmitting L. schirazensis has been confused with L. cubensis, also with G. truncatula and possibly with L. neotropica. Conclusions The new scenario leads to the re-opening of many disease aspects. In Venezuela, altitude appears to be the main factor influencing fascioliasis distribution. Human infection shows an altitude pattern similar to other Andean countries, although a differing highland/lowland impact on animal infection does not appear evident. The overlap of G. truncatula, L. cubensis and probably also L. neotropica in temperate and cold zones suggests a higher risk for human infection in mid and high altitude areas. A lymnaeid species mapping by means of DNA markers becomes a priority to determine human and animal fascioliasis distribution in Venezuela, owing to the importance of lymnaeid vectors in defining transmission and epidemiological patterns.

2011-01-01

322

Hypsilara royi gen. n. and sp. n. (Coleoptera, Elmidae, Larainae) from Southern Venezuela, with a revised key to Larainae of the Western Hemisphere  

PubMed Central

Abstract Here we describe a new genus, for a new species of riffle beetle, Hypsilara royi gen. n. and sp. n., from the tepui Cerro de la Neblina in southern Venezuela. This new genus can be distinguished from all other laraine genera by its small size (ca. 4.5 mm) and the presence of a shallow, wide, V-shaped groove across the apical third of the pronotum. An updated key to the genera of Western Hemisphere Larainae is provided, along with information on habitat and collection methods for this taxon.

Maier, Crystal A.; Spangler, Paul J.

2011-01-01

323

The Siquisique basalts and gabbros, Los Algodones, Venezuela: late Cretaceous oceanic plateau formed within the proto-Caribbean plate?  

NASA Astrophysics Data System (ADS)

Basalts and gabbros, exposed near Siquisique, Venezuela have previously been interpreted as Jurassic mid-ocean ridge basalts, on the basis of an ammonite found in nearby, but not obviously intercalated, sediments (Bartok, 1985). This, combined with their current tectonic position, well within the continent, and because they accreted before the Cretaceous ‘Great Arc’ of the Caribbean, has led to the Siquisique igneous rocks being widely regarded as Jurassic ‘normal’ mid-ocean ridge basalts and gabbros formed as North and South America rifted apart. We present new geochemical and chronological data which shows that the Siquisique igneous rocks are 95-90Ma and have a chemistry which is more consistent with derivation from a deep mantle plume, than a mid-ocean ridge. It is clear that these basalts represent part of the original ocean floor of the Caribbean, which formed before the tectonic emplacement of the present-day Caribbean from the Pacific. Chemically similar basalts and gabbros at El Copey on Araya Peninsula and Sans Souci in northern Trinidad also accreted to the continental margin of South America before the ‘Great Arc’ of the Caribbean and may well be part of the same intra-Caribbean ‘plume event’. These exposures all indicate that the oceanic crust of the proto-Caribbean, was likely to have consisted (at least in part) of thickened oceanic crust formed by melting of a hot-mantle plume. Although the Siquisique rocks formed at a similar time to the Caribbean-Colombian oceanic plateau they were not derived from the same mantle plume. This supports previous suggestions (Kerr & Tarney, 2005; Snow et al. 2005) that the period around ~90Ma (like that around 120Ma) was marked by a significant upsurge in global plume-related magmatic activity. This activity is likely to have contributed significantly to the major worldwide oceanic anoxia event (OAE2) around the Cenomanian-Turonian boundary (93.4Ma)(Kerr, 1998; Snow et al. 2005). Significantly, this discovery requires a revision of our current understanding of Caribbean plate tectonic evolution. References Bartok, P.E., et al. 1985. The Siquisique Ophiolites, Northern Lara State, Venezuela - a discussion on their Middle Jurassic Ammonites and Tectonic Implications. GSA Bulletin 96, 1050-1055. Kerr, A.C., 1998. Oceanic plateau formation: A cause of mass extinction and black shale deposition around the Cenomanian-Turonian boundary. J Geol Soc London 155, 619-626. Kerr, A.C., Tarney, J., 2005. Tectonic evolution of the Caribbean and northwestern South America: The case for accretion of two Late Cretaceous oceanic plateaus. Geology 33, 269-272. Snow, L.G. et al. 2005. Trace element abundances in the Rock Canyon Anticline, Pueblo, Colorado, marine sedimentary section and their relationship to Caribbean plateau construction and oxygen anoxic event 2. Paleoceanography 20, doi. 10.1029/2004PA001093.

Kerr, A. C.; Neill, I.; Urbani, F.; Spikings, R.; Barry, T.; Tarney, J.

2009-12-01

324

Layered mantle structure beneath the western Guyana Shield, Venezuela: Evidence from diamonds and xenocrysts in Guaniamo kimberlites  

NASA Astrophysics Data System (ADS)

Mantle xenoliths and xenocrysts from Guaniamo, Venezuela kimberlites record equilibration conditions corresponding to a limited range of sampling in the lithosphere (100-150 km). Within this small range, however, compositions vary considerably, but regularly, defining a strongly layered mantle sequence. Major and trace element compositions suggest the following lithologic sequence: highly depleted lherzolite from 100 to 115 km, mixed ultra-depleted harzburgite and lherzolite from 115 to 120 km, relatively fertile lherzolite from 120 to 135 km, and mixed depleted harzburgite and relatively fertile lherzolite from 135 to 150 km. Based on comparison with well-documented mantle peridotites and xenocrysts from elsewhere, we conclude that the Meso-proterozoic Cuchivero Province (host to the Guaniamo kimberlites) is underlain by depleted and ultra-depleted shallow Archean mantle that was underplated, and uplifted, by Proterozoic subduction, perhaps more than once. These Proterozoic subduction events introduced less-depleted oceanic lithosphere beneath the Archean section, which remains there and is the source of the abundant Guaniamo eclogite-suite diamonds that have ocean-floor geochemical signatures. Although diamond-indicative low-Ca Cr-pyrope garnets are abundant, they are derived primarily from the shallow depleted layer within the field of graphite stability, and the rare peridotite-suite diamonds are either metastably preserved at these shallow depths, or were derived from the small amount of depleted lithosphere sampled by these kimberlites that remains within the diamond stability field (the mixture of Archean and Proterozoic mantle in the depth range 135-150 km).

Schulze, Daniel J.; Canil, Dante; Channer, Dominic M. DeR.; Kaminsky, Felix V.

2006-01-01

325

Analysis of Transient and Catalytic Desosamine-binding Pockets in Cytochrome P-450 PikC from Streptomyces venezuelae*  

PubMed Central

The cytochrome P-450 PikC from Streptomyces venezuelae exhibits significant substrate tolerance and performs multiple hydroxylation reactions on structurally variant macrolides bearing the deoxyamino sugar desosamine. In previously determined co-crystal structures (Sherman, D. H., Li, S., Yermalitskaya, L. V., Kim, Y., Smith, J. A., Waterman, M. R., and Podust, L. M. (2006) J. Biol. Chem. 281, 26289–26297), the desosamine moiety of the native substrates YC-17 and narbomycin is bound in two distinct buried and surface-exposed binding pockets, mediated by specific interactions between the protonated dimethylamino group and the acidic amino acid residues Asp50, Glu85, and Glu94. Although the Glu85 and Glu94 negative charges are essential for maximal catalytic activity of native enzyme, elimination of the surface-exposed negative charge at Asp50 results in significantly enhanced catalytic activity. Nevertheless, the D50N substitution could not rescue catalytic activity of PikCE94Q based on lack of activity in the corresponding double mutant PikCD50N/E94Q. To address the specific role for each desosamine-binding pocket, we analyzed the x-ray structures of the PikCD50N mutant co-crystallized with narbomycin (1.85Å resolution) and YC-17 (3.2Å resolution). In PikCD50N, the desosamine moiety of both YC-17 and narbomycin was bound in a catalytically productive “buried site.” This finding suggested a two-step substrate binding mechanism, whereby desosamine is recognized in the two subsites to allow the macrolide substrate to sequentially progress toward a catalytically favorable orientation. Collectively, the binding, mutagenesis, kinetic, and x-ray structural data suggest that enhancement of the catalytic activity of PikCD50N is due to the facilitated relocation of substrate to the buried site, which has higher binding affinity, as opposed to dissociation in solution from the transient “surface-exposed site.”

Li, Shengying; Ouellet, Hugues; Sherman, David H.; Podust, Larissa M.

2009-01-01

326

Biological and phylogenetic characterization of a genotype VII Newcastle disease virus from Venezuela: efficacy of field vaccination.  

PubMed

Here we report the biological and molecular characterization of a virulent genotype VII Newcastle disease virus (NDV) circulating in Venezuela and the assessment of the vaccination efficacy under field conditions compared to controlled rearing conditions. Biological pathotyping showed a mean embryo dead time of 50 h and an intracerebral pathogenicity index of 1.86. Sequence-based phylogenetic analysis demonstrated that the virus belongs to genotype VII in class II (a genotype often found in Asia and Africa), representing the first report of the presence of this genotype in the continent of South America. A vaccine-challenge trial in commercial broilers reared in fields or in a experimental setting included dual (live/killed) priming of 1-day-old chicks plus two live NDV and infectious bursal disease virus (IBDV) field vaccinations at days 7 and 17, followed by a very stringent genotype VII NDV challenge at day 28. Serology for NDV and IBDV, bursal integrity, and protection against NDV lethal challenge were assessed. At 28 days, field vaccinates showed significantly lower NDV (1,356 versus 2,384) and higher IBD (7,295 versus 1,489) enzyme-linked immunosorbent assay (ELISA) antibody titers than the experimentally reared birds. A lower bursal size and bursa-body weight ratio (P < 0.05) and higher bursa lesion score were also detected in the field set. Only 57.1% of field vaccinates survived the lethal challenge, differing (P < 0.05) from 90.5% survival in the experimental farm. Overall, results confirmed the presence of the genotype VII viruses in South America and suggest that field-associated factors such as immunosuppression compromise the efficacy of the vaccination protocols implemented. PMID:22238433

Perozo, Francisco; Marcano, Rosmar; Afonso, Claudio L

2012-01-11

327

Biological and Phylogenetic Characterization of a Genotype VII Newcastle Disease Virus from Venezuela: Efficacy of Field Vaccination  

PubMed Central

Here we report the biological and molecular characterization of a virulent genotype VII Newcastle disease virus (NDV) circulating in Venezuela and the assessment of the vaccination efficacy under field conditions compared to controlled rearing conditions. Biological pathotyping showed a mean embryo dead time of 50 h and an intracerebral pathogenicity index of 1.86. Sequence-based phylogenetic analysis demonstrated that the virus belongs to genotype VII in class II (a genotype often found in Asia and Africa), representing the first report of the presence of this genotype in the continent of South America. A vaccine-challenge trial in commercial broilers reared in fields or in a experimental setting included dual (live/killed) priming of 1-day-old chicks plus two live NDV and infectious bursal disease virus (IBDV) field vaccinations at days 7 and 17, followed by a very stringent genotype VII NDV challenge at day 28. Serology for NDV and IBDV, bursal integrity, and protection against NDV lethal challenge were assessed. At 28 days, field vaccinates showed significantly lower NDV (1,356 versus 2,384) and higher IBD (7,295 versus 1,489) enzyme-linked immunosorbent assay (ELISA) antibody titers than the experimentally reared birds. A lower bursal size and bursa-body weight ratio (P < 0.05) and higher bursa lesion score were also detected in the field set. Only 57.1% of field vaccinates survived the lethal challenge, differing (P < 0.05) from 90.5% survival in the experimental farm. Overall, results confirmed the presence of the genotype VII viruses in South America and suggest that field-associated factors such as immunosuppression compromise the efficacy of the vaccination protocols implemented.

Perozo, Francisco; Marcano, Rosmar

2012-01-01

328

Revised seismic history of the El Pilar fault, Northeastern Venezuela, from the Cariaco 1997 earthquake and recent preliminary paleoseismic results  

NASA Astrophysics Data System (ADS)

In light of the July 9, 1997, Cariaco earthquake, it is clearly understood now that damage in the city of Cumaná located in northeastern Venezuela and frequently destroyed by the largest earthquakes since the first recorded event in 1530 is strongly enhanced by poor soil conditions that, in turn, are responsible for site amplification and widespread earthquake-induced effects. Therefore, most previous macroseismic studies of historical earthquakes must be revaluated because those localized high-intensity values at Cumaná surely led to the misestimation of past epicenters. Preliminary paleoseismic results, gathered at three exploratory trenches dug across the surface break of the Cariaco 1997 earthquake in 1998, allow us to associate the 1684 earthquake with this recently ruptured fault segment that extends between the towns of San Antonio del Golfo and Río Casanay (roughly between the two gulfs of Cariaco and Paria, state of Sucre). Other major results from the reassessment of the seismic history of this fault are: (a) the 1766 event seems to have generated in a different source to the El Pilar fault because the size of the felt area suggests that it is an intermediate-depth earthquake; (b) damage to Cumaná produced by the 1797 event suggests that this was a local earthquake, perhaps equivalent to the 1929 earthquake, which ruptured for some 30 km just east of Cumaná into the Gulf of Cariaco; and (c) seismogenic association of the 1530 and 1853 earthquakes still remains unclear but it is very likely that these ruptures occurred offshore, as suggested by the rather large tsunami waves that both events have generated, placing their hypocenters west of Cumaná in the Cariaco Trough. This reassessment also sheds light into the El Pilar fault segmentation and the behavior of its seismogenic barriers through time.

Audemard, Franck A.

2007-07-01

329

Cenozoic oblique collision of South American and Caribbean plates: New evidence in the Coastal Cordillera of Venezuela and Trinidad  

SciTech Connect

The hinterland of the Caribbean Mts. orogen in Trinidad and Venezuela contains schist and gneiss whole protoliths are wholly or partly of continental provenance. The hinterland lies between the foreland thrust belt and terranes. The terranes are alien to continental South America (SA) and may have proto-Caribbean or Caribbean plate origins. The hinterland rocks were widely thought to come from sediments and granitoids of Mesozoic protolithic ages and to be of Cretaceous metamorphic age. Such rocks are now know to be of at least two or more types, as follows: (1) low grade, protoliths of pre-Mesozoic basement and shelfal cover of uncertain age range, inboard locus, Oligocene to mid-Miocene metamorphic ages younging eastward (Caracas, Paria, and Northern Range belts), and (2) higher grade including high P/T, varies protoliths of uncertain age range, Cretaceous and ( )early Paleogene metamorphic ages (Tacagua, Araya, Margarita). The geometry, protoliths, structures, and metamorphic ages of type 1 parautochthoneity and an origin as a thickened wedge of crust-cored passive margin cover. The wedge grew by accretion between about 35 and 20 Ma during oblique transport toward the foreland. The diachroneity of metamorphism implies, as does the timing of foreland deformation, that the wedge evolved in a right-oblique collision between northern SA and terranes moving wholly or partly with the Caribbean plate since the Eocene. Type 2 rocks probably came with the terranes and are products of convergent zone tectonics, either in the proto-Caribbean plate. The hinterland boundaries are brittle thrusts that are out of sequence and imply progressive contraction from mid-Cenozoic to the present.

Speed, R.C. (Northwestern Univ., Evanston, IL (United States)); Russo, R.M. (Carnegie Institute of Washington (United States)); Foland, K.A. (Ohio State Univ., Columbus (United States))

1993-02-01

330

[Genetic diversity of rotavirus group a: correlation between G3 type and severity of the infection. Valencia, Venezuela].  

PubMed

Genetic and antigenic rotavirus (RV) variabilities may have implications in the severity of the infection caused by these agents; however the studies are not conclusive. For that purpose, the mean severity scores of diarrhea episodes caused by RV types G1 and G3 were compared, at Ciudad Hospitalaria "Dr. Enrique Tejera" in Valencia, Venezuela, between 2001-2005. RV were identified by ELISA, G and P types by RT-PCR. The severity of infection was determined using the Ruuska-Vesikari system and the mean severity values were compared using the Student's t-test (two-tailed, 95% CI). RV were detected in 24.5% of patients (3193/13026), being G3 the most common (50.3%), followed by G1 (39.2%), G9 (6.2%), G2 (0.6%), G4 (0.6%) and of mixed infection 3.1% (G1 + G3). Type P[8] was present in 87.3% of samples, 10.9% P[4] and 1.8% P[6]. There were not statistically significant differences (P > or = 0.05) observed between the episodes caused by G1 and G3 when age, breast feeding, and degrees of malnutrition and dehydration were considered. Nevertheless, in the G3 positive group, fever, episodes of more than 6 days, 6 or more evacuations in 24 hours and 3 or more days with vomit, were observed. The mean severity score for the G3 episodes (11.1) was significantly higher (P < 0.05) than for G1 (7.8). These results show that G3 was associated with severe diarrhea, supporting the hypothesis that the knowledge of the variability and frequency of viral types is essential to measure the impact of an anti-rotavirus vaccine. PMID:23781711

González, Rosabel; Rivero, Lisbeth

2013-03-01

331

Identification and Classification of Mass Transport Complexes in Offshore Trinidad/Venezuela and Their Potential Anthropogenic Impact as Tsunamigenic Hazards  

NASA Astrophysics Data System (ADS)

Several late Pleistocene-age seafloor destabilization events have been identified in the continental margin of eastern offshore Trinidad, of sufficient scale to produce tsunamigenic forces. This area, situated along the obliquely-converging-boundary of the Caribbean/South American plates and proximal to the Orinoco Delta, is characterized by catastrophic shelf-margin processes, intrusive-extrusive mobile shales, and active tectonism. A mega-merged, 10,000km2, 3D seismic survey reveals several mass transport complexes that range in area from 11.3km2 to 2017km2. Historical records indicate that this region has experienced submarine landslide- generated tsunamigenic events, including tsunamis that affected Venezuela during the 1700's-1900's. This work concentrates on defining those ancient deep marine mass transport complexes whose occurrence could potentially triggered tsunamis. Three types of failures are identified; 1) source-attached failures that are fed by shelf edge deltas whose sediment input is controlled by sea-level fluctuations and sedimentation rates, 2) source-detached systems, which occur when upper slope sediments catastrophically fail due to gas hydrate disruptions and/or earthquakes, and 3) locally sourced failures, formed when local instabilities in the sea floor trigger relatively smaller collapses. Such classification of the relationship between slope mass failures and the sourcing regions enables a better understanding of the nature of initiation, length of development history and petrography of such mass transport deposits. Source-detached systems, generated due to sudden sediment remobilizations, are more likely to disrupt the overlying water column causing a rise in tsunamigenic risk. Unlike 2D seismic, 3D seismic enables scientists to calculate more accurate deposit volumes, improve deposit imaging and thus increase the accuracy of physical and computer simulations of mass failure processes.

Moscardelli, L.; Wood, L. J.

2006-12-01

332

Enhanced Heterologous Production of Desosaminyl Macrolides and Their Hydroxylated Derivatives by Overexpression of the pikD Regulatory Gene in Streptomyces venezuelae?  

PubMed Central

To elevate the production level of heterologous polyketide in Streptomyces venezuelae, an additional copy of the positive regulatory gene pikD was introduced into the pikromycin (Pik) polyketide synthase (PKS) deletion mutant of S. venezuelae ATCC 15439 expressing tylosin PKS genes. The resulting mutant strain showed enhanced production of both tylactone (TL) and desosaminyl tylactone (DesTL) of 2.7- and 17.1-fold, respectively. The notable increase in DesTL production strongly suggested that PikD upregulates the expression of the desosamine (des) biosynthetic gene cluster. In addition, two hydroxylated forms of DesTL were newly detected from the extract of this mutant. These hydroxylated forms presumably resulted from a PikD-dependent increase in expression of the pikC gene that encodes P450 hydroxylase. Gene expression analysis by reverse transcriptase PCR and bioconversion experiments of 10-deoxymethynolide, narbonolide, and TL into the corresponding desosaminyl macrolides indicated that PikD is a positive regulator of the des and pikC genes, as well as the Pik PKS genes. These results demonstrate the role of PikD as a pathway-specific positive regulator of the entire Pik biosynthetic pathway and its usefulness in the development of a host-vector system for efficient heterologous production of desosaminyl macrolides and novel hydroxylated compounds.

Jung, Won Seok; Jeong, Soon Jeong; Park, Sung Ryeol; Choi, Cha Yong; Park, Byoung Chul; Park, Je Won; Yoon, Yeo Joon

2008-01-01

333

Development of a Streptomyces venezuelae-Based Combinatorial Biosynthetic System for the Production of Glycosylated Derivatives of Doxorubicin and Its Biosynthetic Intermediates ? †  

PubMed Central

Doxorubicin, one of the most widely used anticancer drugs, is composed of a tetracyclic polyketide aglycone and l-daunosamine as a deoxysugar moiety, which acts as an important determinant of its biological activity. This is exemplified by the fewer side effects of semisynthetic epirubicin (4?-epi-doxorubicin). An efficient combinatorial biosynthetic system that can convert the exogenous aglycone ?-rhodomycinone into diverse glycosylated derivatives of doxorubicin or its biosynthetic intermediates, rhodomycin D and daunorubicin, was developed through the use of Streptomyces venezuelae mutants carrying plasmids that direct the biosynthesis of different nucleotide deoxysugars and their transfer onto aglycone, as well as the postglycosylation modifications. This system improved epirubicin production from ?-rhodomycinone by selecting a substrate flexible glycosyltransferase, AknS, which was able to transfer the unnatural sugar donors and a TDP-4-ketohexose reductase, AvrE, which efficiently supported the biosynthesis of TDP-4-epi-l-daunosamine. Furthermore, a range of doxorubicin analogs containing diverse deoxysugar moieties, seven of which are novel rhodomycin D derivatives, were generated. This provides new insights into the functions of deoxysugar biosynthetic enzymes and demonstrates the potential of the S. venezuelae-based combinatorial biosynthetic system as a simple biological tool for modifying structurally complex sugar moieties attached to anthracyclines as an alternative to chemical syntheses for improving anticancer agents.

Han, Ah Reum; Park, Je Won; Lee, Mi Kyeong; Ban, Yeon Hee; Yoo, Young Ji; Kim, Eun Ji; Kim, Eunji; Kim, Byung-Gee; Sohng, Jae Kyung; Yoon, Yeo Joon

2011-01-01

334

Serological and molecular diagnosis of bovine viral diarrhoea virus and evidence of other viral infections in dairy calves with respiratory disease in Venezuela.  

PubMed

An investigation based on 2 studies was carried out to assess the involvement of bovine virus diarrhoea virus (BVDV), bovine herpesvirus type 1 (BHV-1), and bovine respiratory syncytial virus (BRSV) in calf respiratory disease in dairy farms in Venezuela. In the first study, 8 farms were selected and paired serum samples from 42 calves with respiratory disease were tested by ELISA for antibodies to the 3 viruses. Seroconversion to BVDV, BHV-1, and BRSV was found to 5, 2, and 6 farms out of the 8, respectively. The proportion of calves that showed seroconversion to BVDV, BHV-1, and BRSV were 19%, 14%, and 26%, respectively. In the second study, another farm having previous serological evidence of BVDV infection was selected. The decline of maternal antibodies against BVDV was monitored in 20 calves and the half-life of maternal antibodies was 34 +/- 12 days presumably indicating an early natural infection with BVDV. Furthermore, sera free of BVDV antibodies that were collected in studies 1 and 2 and were assayed for the presence of BVDV by nested RT-PCR. Two BVDV strains were detected and compared to those of ruminant and porcine pestiviruses. Both strains were assigned to subgroup Ib of type I BVDV. This investigation provides information on BVDV genotypes circulating in Venezuela and may contribute to the establishment of official control programmes against the viruses studied. PMID:10605142

Obando, C; Baule, C; Pedrique, C; Veracierta, C; Belák, S; Merza, M; Moreno-Lopez, J

1999-01-01

335

Layered Mantle Structure Beneath the Western Guyana Shield, Venezuela: Evidence From Diamonds and Xenocrysts in Guaniamo Kimberlites  

NASA Astrophysics Data System (ADS)

The Neo-Proterozoic (712 Ma) kimberlites from Guaniamo, Venezuela contain abundant low-Ca (harzburgitic) Cr-pyrope garnet xenocrysts, as well as lherzolitic Cr-pyropes, but few diamonds belonging to the peridotite-suite. Trace element compositions suggest three groupings of garnet. Most Cr-pyropes, both lherzolitic and harzburgitic, are highly depleted in magmaphile elements (e.g., Y < 5 ppm, Zr < 31 ppm) and have sinusoidal REE patterns. A second group (primarily lherzolites) has relatively undepleted characteristics (e.g., 9 - 14 ppm Y, Zr < 22 ppm), and typical LREE-depleted REE patterns. A few garnets show enrichment typical of peridotites metasomitised by relatively low-temperature mantle fluids (e.g., 7 - 9 ppm Y, 30 - 90 ppm Zr). Ni-in-garnet thermometry allows depths of origin to be estimated for the garnet xenocrysts by projecting temperatures onto the conductive geothermal gradient (40 Mw/m2 heat flow equivalent) obtained from compositions of Guaniamo Cr-diopside xenocrysts using the Nimis and Taylor method. Within the limited depth range of lithosphere sampled by the kimberlites (100-150 km) compositions vary considerably, but regularly, defining a strongly layered mantle section. Major and trace element compositions suggest the following lithologic sequence: highly-depleted lherzolite from 100 to 115 km, mixed ultra-depleted harzburgite and lherzolite from 115 to 120 km, relatively undepleted lherzolite from 120 to 135 km, mixed depleted harzburgite and relatively-undepleted lherzolite from 135 to 150 km. Based on comparison with well-documented mantle peridotites and xenocrysts from elsewhere, we conclude that the Meso-Proterozoic Cuchivero Province of the Guyana Shield (host to the Guaniamo kimberlites) is underlain by depleted and ultra-depleted shallow Archean mantle which was under-plated, and uplifted, by Proterozoic subduction, perhaps more than once. These Proterozoic subduction events introduced less-depleted oceanic lithosphere beneath the Archean section, which remained there and was the source of the abundant Guaniamo eclogite-suite diamonds that have ocean-floor carbon and oxygen isotope signatures. Although diamond-indicative low-Ca Cr-pyropegarnets are abundant, they were derived primarily from the shallow depleted layer within the field of graphite stability, and the rare peridotite-suite diamonds were either metastably preserved at these shallow depths, or were derived from the small amount of depleted lithosphere sampled by these kimberlites that remained within the diamond stability field (the mixture of Archean and Proterozoic mantle in the depth range 135-150 km).

Schulze, D. J.; Canil, D.; Channer, D. M.; Kaminsky, F. V.

2004-12-01

336

Miocene stratigraphy and depositional framework of northeastern Maracaibo Basin, Venezuela: Implications for reservoir heterogeneity prediction in tectonically-active settings  

NASA Astrophysics Data System (ADS)

Lateral and vertical changes in regime variables have a direct impact on the nature and distribution of macroscopic reservoir heterogeneity in tectonically-active basins. This relationship was tested in a clastic Miocene interval of the northeastern region of the Maracaibo Basin, Venezuela, by the integration and analysis of a comprehensive subsurface dataset. Four unconformity-bounded sequences record changes in accommodation, sediment supply, and sediment dispersal directions. These shifts were controlled by the uplift of the Sierra de Perija and by the marine connection between the Maracaibo and Falcon basins. The oldest sequence corresponds to the Early Miocene La Rosa Formation, which represents the episode of greatest increase in the regime ratio. After experiencing the maximum flooding event of the Neogene, accommodation space was filled by a mixed wave- and tide-influenced system of deltas and prograding shorelines that were fed from the west. Waterflooding in these reservoirs has been successful despite the compartmentalization and increased heterogeneity produced by rapid marine flooding of the deltaic pulses. Increased uplift and erosion of the sediment source areas shifted the regime ratio to supply dominated, causing a major fall in relative sea level and the development of a network of southwest- to northeast-oriented fluvially incised valleys. This event separates the La Rosa Formation from a younger sequence of highly heterogeneous tide-dominated estuarine deposits, overlain by tidal flats and tide-dominated deltaic sediments, that characterize the Lagunillas Inferior member of the Lagunillas Formation. The stratigraphic relationships and sedimentary fill of these incised valleys explain the complex nature of the LL-03/LL-05 reservoir boundary to the southeast of the study area. Continuing tectonic activity resulted in yet another significant drop in relative sea level, recorded by the abrupt onset of southeasterly flowing, mixed-load rivers, in the upper section of the Lagunillas Inferior Member. These deposits form the shelf-equivalent lowstand systems tract of the next younger sequence, which also includes the Laguna Member. A significant potential for targeting uncontacted and bypassed hydrocarbons exists in these reservoirs. Waterflooding has been relatively successful, but differences in directional permeability may be encountered across the fluvial entrenchment surfaces.

Guzman Espinal, Jose Ignacio

1999-11-01

337

Water Soluble Organic Nitrogen in atmospheric aerosol samples from urban, sub-urban and pristine areas of Venezuela  

NASA Astrophysics Data System (ADS)

Concentrations of water soluble organic nitrogen (WSON) were determined in atmospheric total suspended particles (TSP) collected between September of 2005 and May of 2006, in an urban continental (Caracas, 10° 29' 09'' N, 66° 53' 48'' W), an urban coastal (Catia la mar, 10° 35' 47'' N, 67° 01' 45'' W), a sub-urban coastal (Osma, 10° 32' N, 67° 28' W), a suburban continental (Altos de Pipe, 10° 23' 41'' N, 63° 59' 10'' W), a pristine coastal (Isla de Aves, 15° 40' N, 63° 36' W) and a pristine continental (La Gran Sabana National Park, 5° 41' 30'' N, 61° 34' 20'' W) areas of Venezuela. TSP samples were collected using a Hi-Vol airborne particle sampler. TSP were impacted on a fiberglass filter pretreated under 400° C for 4 hours to minimize organic nitrogen contamination. Ultra sound water extractions of the sample filters were performed and their NH4+, NO2- and NO3- concentrations were determined by ion exchange liquid chromatography. The water extracts were UV digested and the nitrogen inorganic ions were analyzed after the UV exposure. WSON concentrations were calculated by the difference between the inorganic nitrogen concentrations before and after UV digestion. Ninety five percent of the aerosol samples collected in the suburban and pristine areas showed a WSON concentration range from 0.03 to 0.6 ?g/m3 whereas in urban areas the range was 0.21 to 1.09 ?g/m3. These concentration values are on the same order of magnitude than the previously found in other tropical and subtropical areas. The contribution of aerosol WSON to the total soluble nitrogen in the coastal urban, sub-urban and pristine areas ranged from 23 to 67%, while in Caracas was smaller (38±8%, n=5). Therefore, aerosol WSON provides an important source of nitrogen to these pristine and suburban ecosystems, which could potentially have implications on the nutrient cycling. There was a statistically significant linear correlation between the aerosol WSON and the water soluble inorganic nitrogen (WSIN) for the urban coastal, sub-urban and pristine zones (R2= 0.81, n=22). This correlation could be explained by a possible source of secondary water soluble organic aerosols derived by the reaction between biogenic volatile organic compounds (VOCs), such as isoprene, and nitrogen oxides (NOx) present in the atmosphere of these regions. Such correlation was not found in Caracas, possibly due to the fact that in this city the major source of VOCs is fossil fuel combustion which produces mostly non soluble aliphatic VOCs. These compounds could most likely produce low water soluble secondary organic nitrogen aerosols.

Canelon, R.; Giuliante, A.; Aguiar, G.; Ghneim, T.; Perez, T.

2007-12-01

338

Earthquake source imaging by high-resolution array analysis at regional distances: the 2010 M7 Haiti earthquake as seen by the Venezuela National Seismic Network  

NASA Astrophysics Data System (ADS)

Back projection of teleseismic waves based on array processing has become a popular technique for earthquake source imaging,in particular to track the areas of the source that generate the strongest high frequency radiation. The technique has been previously applied to study the rupture process of the Sumatra earthquake and the supershear rupture of the Kunlun earthquakes. Here we attempt to image the Haiti earthquake using the data recorded by Venezuela National Seismic Network (VNSN). The network is composed of 22 broad-band stations with an East-West oriented geometry, and is located approximately 10 degrees away from Haiti in the perpendicular direction to the Enriquillo fault strike. This is the first opportunity to exploit the privileged position of the VNSN to study large earthquake ruptures in the Caribbean region. This is also a great opportunity to explore the back projection scheme of the crustal Pn phase at regional distances,which provides unique complementary insights to the teleseismic source inversions. The challenge in the analysis of the 2010 M7.0 Haiti earthquake is its very compact source region, possibly shorter than 30km, which is below the resolution limit of standard back projection techniques based on beamforming. Results of back projection analysis using the teleseismic USarray data reveal little details of the rupture process. To overcome the classical resolution limit we explored the Multiple Signal Classification method (MUSIC), a high-resolution array processing technique based on the signal-noise orthognality in the eigen space of the data covariance, which achieves both enhanced resolution and better ability to resolve closely spaced sources. We experiment with various synthetic earthquake scenarios to test the resolution. We find that MUSIC provides at least 3 times higher resolution than beamforming. We also study the inherent bias due to the interferences of coherent Green’s functions, which leads to a potential quantification of biased uncertainty of the back projection. Preliminary results from the Venezuela data set shows an East to West rupture propagation along the fault with sub-Rayleigh rupture speed, consistent with a compact source with two significant asperities which are confirmed by source time function obtained from Green’s function deconvolution and other source inversion results. These efforts could lead the Venezuela National Seismic Network to play a prominent role in the timely characterization of the rupture process of large earthquakes in the Caribbean, including the future ruptures along the yet unbroken segments of the Enriquillo fault system.

Meng, L.; Ampuero, J. P.; Rendon, H.

2010-12-01

339

Analysis of the performance of the M-6 area of the Tia Juana Field, Venezuela, under primary, steam-soak, and steamdrive conditions  

SciTech Connect

This paper deals with the reservoir performance of the M-6 Project Area in the south-east of the Tia Juana field. The field is one of the four heavy oil fields located along the eastern shore of Lake Maracaibo in Venezuela, collectively known as the Bolivar Coast fields. Since the early 1930's the area covered by these fields subsides, an observation which one could not fail to make in this swampy coastal area. The subsidence prompted the construction of coastal dykes for protection against flooding and also the installation of a network of benchmarks which are surveyed biannually, to monitor ground level changes in detail. It soon became apparent that there was a direct correlation between subsidence and oil withdrawal, implying that the compaction phenomenon acts as an oil production mechanism. This established a cause/effect chain of oil production/pressure decline/formation compaction/surface subsidence which has since been a fertile field for investigation.

Puig, F.; Schenk, L.

1984-04-01

340

The Streptomyces venezuelae pikAV gene contains a transcription unit essential for expression of enzymes involved in glycosylation of narbonolide and 10-deoxymethynolide.  

PubMed

In Streptomyces venezuelae, four polyketide synthase (PKS) polypeptides encoded by pikAI-pikAIV are used to generate 10 and 12-membered macrocyclic structures, narbonolide and 10-deoxymethynolide. Sequence analysis suggests these genes are translationally coupled with downstream genes, pikAV (encoding a type II thioesterase), desVIII-desVI (encoding enzymes responsible for production of the final glycosylated products pikromycin, narbomycin, methymycin and neomethymycin) and desR (a resistance gene). Type II thioesterases have been suggested to have an editing function in polyketide biosynthesis and deletion of the corresponding genes often leads to decreased levels of polyketide production. Surprisingly an in-frame deletion of 687 bp of the 843 bp pikAV ORF led to a strain SC1022 that produced normal yields of polyketide products, but only in the aglycone form. Plasmid-based expression of the desVIII-VI and desR in the SC1022 strain completely restored production of glycosylated products, despite the absence of a functional pikAV gene product. Under these conditions the PikAV TEII therefore does not play an important role in polyketide biosynthesis, and its function remains an enigma. These observations also demonstrate that the region of pikAV DNA deleted in strain SC1022 contains a transcription unit essential for expression of the des genes. A sequence alignment of PikAV with members of the highly conserved type II thioesterases revealed a short divergent region at the carboxy terminus, suggesting a region of pikAV that might contain such a transcription unit. DNA containing this region of pikAV was shown to be able to increase plasmid-based expression of both crotonyl CoA reductase gene (ccr) and the erythromycin resistance gene (ermE) in S. venezuelae. PMID:11223265

Chen, S; Roberts, J B; Xue, Y; Sherman, D H; Reynolds, K A

2001-01-24

341

Genes Required for Aerial Growth, Cell Division, and Chromosome Segregation Are Targets of WhiA before Sporulation in Streptomyces venezuelae  

PubMed Central

ABSTRACT WhiA is a highly unusual transcriptional regulator related to a family of eukaryotic homing endonucleases. WhiA is required for sporulation in the filamentous bacterium Streptomyces, but WhiA homologues of unknown function are also found throughout the Gram-positive bacteria. To better understand the role of WhiA in Streptomyces development and its function as a transcription factor, we identified the WhiA regulon through a combination of chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray transcriptional profiling, exploiting a new model organism for the genus, Streptomyces venezuelae, which sporulates in liquid culture. The regulon encompasses ~240 transcription units, and WhiA appears to function almost equally as an activator and as a repressor. Bioinformatic analysis of the upstream regions of the complete regulon, combined with DNase I footprinting, identified a short but highly conserved asymmetric sequence, GACAC, associated with the majority of WhiA targets. Construction of a null mutant showed that whiA is required for the initiation of sporulation septation and chromosome segregation in S. venezuelae, and several genes encoding key proteins of the Streptomyces cell division machinery, such as ftsZ, ftsW, and ftsK, were found to be directly activated by WhiA during development. Several other genes encoding proteins with important roles in development were also identified as WhiA targets, including the sporulation-specific sigma factor ?WhiG and the diguanylate cyclase CdgB. Cell division is tightly coordinated with the orderly arrest of apical growth in the sporogenic cell, and filP, encoding a key component of the polarisome that directs apical growth, is a direct target for WhiA-mediated repression during sporulation.

Bush, Matthew J.; Bibb, Maureen J.; Chandra, Govind; Findlay, Kim C.; Buttner, Mark J.

2013-01-01

342

Long term in-situ observations of biomass burning aerosol at a high altitude station in Venezuela - sources, impacts and inter annual variability  

NASA Astrophysics Data System (ADS)

First long-term observations of South American biomass burning aerosol within the tropical lower free troposphere are presented. The observations were conducted between 2007 and 2009 at a high altitude station (4765 m a.s.l.) on the Pico Espejo, Venezuela. Sub-micron aerosol volume, number concentrations of primary particles and particle absorption were observed. Orographic lifting and shallow convection leads to a distinct diurnal cycle at the station. It enables measurements within the lower free troposphere during night time and observations of boundary layer air masses during day time and at their transitional regions. The seasonal cycle is defined by a wet rainy season and a dry biomass burning season. The particle load of biomass burning aerosol is dominated by fires in the Venezuelan savannah. Increases of aerosol concentrations could not be linked to long-range transport of biomass burning plumes from the Amazon basin or Africa due to effective wet scavenging of particles. Highest particle concentrations were observed within boundary layer air masses during the dry season. Ambient sub-micron aerosol volume reached 1.4 ± 1.3 ?m3 cm-3, heated (300 °C) particle number concentrations 510 ± 420 cm-3 and the absorption coefficient 0.91 ± 1.2 Mm-1. The respective concentrations were lowest within the lower free troposphere during the wet season and averaged at 0.19 ± 0.25 ?m3 cm-3, 150 ± 94 cm-3 and 0.15 ± 0.26 Mm-1. A decrease of particle concentrations during the dry seasons from 2007-2009 could be connected to a decrease in fire activity in the wider region of Venezuela using MODIS satellite observations. The variability of biomass burning is most likely linked to the El Niño-Southern Oscillation (ENSO). Low biomass burning activity in the Venezuelan savannah was observed to follow La Niña conditions, high biomass burning activity followed El Niño conditions.

Hamburger, T.; Matis?ns, M.; Tunved, P.; Ström, J.; Calderon, S.; Hoffmann, P.; Hochschild, G.; Gross, J.; Schmeissner, T.; Krejci, R.

2013-05-01

343

Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela - sources, impacts and interannual variability  

NASA Astrophysics Data System (ADS)

First long-term observations of South American biomass burning aerosol within the tropical lower free troposphere are presented. The observations were conducted between 2007 and 2009 at a high altitude station (4765 m a.s.l.) on the Pico Espejo, Venezuela. Sub-micron particle volume, number concentrations of primary particles and particle absorption were observed. Orographic lifting and shallow convection leads to a distinct diurnal cycle at the station. It enables measurements within the lower free troposphere during night-time and observations of boundary layer air masses during daytime and at their transitional regions. The seasonal cycle is defined by a wet rainy season and a dry biomass burning season. The particle load of biomass burning aerosol is dominated by fires in the Venezuelan savannah. Increases of aerosol concentrations could not be linked to long-range transport of biomass burning plumes from the Amazon basin or Africa due to effective wet scavenging of particles. Highest particle concentrations were observed within boundary layer air masses during the dry season. Ambient sub-micron particle volume reached 1.4±1.3 ?m3 cm-3, refractory particle number concentrations (at 300 °C) 510±420 cm-3 and the absorption coefficient 0.91±1.2 Mm-1. The respective concentrations were lowest within the lower free troposphere during the wet season and averaged at 0.19±0.25 ?m3 cm-3, 150±94 cm-3 and 0.15±0.26 Mm-1. A decrease of particle concentrations during the dry seasons from 2007-2009 could be connected to a decrease in fire activity in the wider region of Venezuela using MODIS satellite observations. The variability of biomass burning is most likely linked to the El Niño-Southern Oscillation (ENSO). Low biomass burning activity in the Venezuelan savannah was observed to follow La Niña conditions, high biomass burning activity followed El Niño conditions.

Hamburger, T.; Matis?ns, M.; Tunved, P.; Ström, J.; Calderon, S.; Hoffmann, P.; Hochschild, G.; Gross, J.; Schmeissner, T.; Wiedensohler, A.; Krejci, R.

2013-10-01

344

Optical Response of the Atmosphere During the Caribbean Total Solar Eclipses of 26 February 1998 and of 3 February 1916 at Falcón state, Venezuela  

NASA Astrophysics Data System (ADS)

An investigation of the optical response of the atmosphere before, during, and after the total solar eclipse of 26 February 1998 at the Caribbean Peninsula of Paraguaná (Falcón State) in Venezuela, was made by measuring photometrically the intensity of the sky brightness in three strategic directions: zenith, horizon anti-parallel or opposite the umbra path, and horizon perpendicular to this path. From these measurements, and by applying in an inverse way an empirical photometric model, very rough estimations of the extinction coefficient, and also of the average optical depth, were obtained in one of these particular directions. However based on meteorological measurements such as those of relative humidity and temperature, and applying a different model, a better estimation in the visual of the total global extinction coefficient of the sky (except the horizon), were made considering the contribution of each component: atmospheric aerosol, water vapour, ozone and Rayleigh scattering. It is shown that this global coefficient is mostly dependent upon aerosol extinction. In spite of the strong reduction of sky brightness photometrically observed during the totality, the results show that the sky was not dark. This is confirmed by the results obtained for the total global extinction coefficient. Additionally it is estimated that the total solar eclipse that took place also in Falcón State, Venezuela, at the beginning of the last century on 3 February 1916, was ~30% darker that the 1998 eclipse, and that atmospheric aerosol played a relevant and similar role in the scattering of sunlight during the totality as it was for 1998's. Visual observations made during each event, which show that at length only one or two bright stars could be seen in the sky, support the results obtained for both eclipses.

Peñaloza-Murillo, Marcos A.

2002-11-01

345

[Environmental evaluation near a fuel vendor within Parque Nacional Morrocoy, Venezuela. II: Water quality, sediments and biota].  

PubMed

This paper is the second part of a base line study carried out in the coastal region near a marine service station located in Morrocoy National Park, Venezuela. Results from a physical and chemical characterization of the water and sediments of four sites located around the service station are presented. The physical and chemical factors measured in water included: temperature, salinity, specific conductance, dissolved oxygen, saturation percentage of dissolved oxygen, pH, total suspended solids, transparency, oil and grease, total residual petroleum hydrocarbon, vanadium and lead, total coliform bacteria, and the presence of coliform bacteria. The factors measured in sediments include: granulometry, organic material, total carbonates, vanadium, lead, oil and grease, and total hydrocarbons. In addition, the amount of vanadium and lead in sample tissue from three species which are abundant and widely distributed in each site was measured in order to evaluate the potential of these species as bio-indicators. The water in the area where this study was conducted is shallow, warm, and thermally homogeneous, with high salinity and normal pH and dissolved oxygen, and supersaturated with oxygen in certain hours in sites adjacent to abundant underwater vegetation. The water is moderately turbid with a tendency towards less dissolved oxygen with increased depth. The estimated values of NMP/100 ml of the coliform fecal organisms is within legal limits even though the total number of water coliforms measured in Site 2 was ten times higher than in Site 1. This increase is associated with the proximity of Site 2 to an outflow of pre-treated sewage. The values of TRPH in the water collected from each site were low and very close to the detection limit (0.8/ml). Vanadium was not found, while lead was detected in 11 of the 12 samples. Compared to the values measured for Site 1, which was the local reference, only one sample had a concentration of three times the maximum baseline. The amount of lead found in all analyzed samples was acceptable, according to the standards set by the State of Washington (maximum value: 292 mg/kg), while the concentration of lead in the sediments around the supply dock were 1.5 to 3.4 times greater than the Dutch norm. It can be concluded that there is no evidence of an accumulation of Va or Pb in the species selected as bioindicators. An observation program is proposed in which variables similar to those measured for this characterization will be studied with some modifications. A more intense sampling of some variables is recommended (lead in water and sediments, total coliform and fecal matter in consecutive samples and in days following a high concentration of visitors) as is the elimination or minimization of other variables. PMID:15266791

Rada, M; Losada, F

2000-12-01

346

Venezuela: Penas y olvidos  

Microsoft Academic Search

Sectores de la oposición que quisieron capitalizar para sí el sufrimiento de las muertes del 11 de abril, hicieron suya esos días una frase que, imagino, tomaron de una canción de Rubén Blades: ‘Prohibido olvidar’. La sentencia no deja de ser curiosa en un país donde la falta de memoria, los olvidos convenientes, cuya acción la realidad histórica se encarga

Javier Lasarte Valcárcel

2002-01-01

347

PRACTICAS DE REHABILITACION DE ARIDISOLES Y ENTISOLES DEL NORTE DE LA PATAGONIA A FECTADOS POR LA APERTURA DE LINEAS SISMICAS  

Microsoft Academic Search

The north Patagonian region of Argentina is affected by desertification processes. The combination of petroleum activity and the existence of seismic lines across of this arid area increases desertification. The purpose of this study was to evaluate the application of different soil rehabilitation practices. Five soils, representative of the most important landscape units were selected: Typic Torripsamment, Argic Petrocalcid, Natric

P SCHMID; P BROQUEN

348

Refuerzo de la Vivienda Economica en Zonas Sismicas: Estudios Experimentales (Strengthening of Low Houses in Seismic Areas: Experimental Studies).  

National Technical Information Service (NTIS)

In order to evaluate the efficiency of several strengthening methods for adobe houses, nine 1:2.5 scale models were tested in a shaking table under the effect of the accelerograms of three major actual earthquakes; mechanical properties of adobe masonry a...

O. Hernandez R. Meli M. Padilla E. Valencia

1981-01-01

349

Tectonic and thermal history of the western Serrania del Interior foreland fold and thrust belt and Guarico Basin, north central Venezuela: Implications of new apatite fission track analysis and seismic interpretation  

Microsoft Academic Search

Structural analysis, interpretation of seismic reflection lines, and apatite fission-track analysis in the Western Serrania del Interior fold and thrust belt and in the Guarico basin of north-central Venezuela indicate that the area underwent Mesozoic and Tertiary-to-Recent deformation. Mesozoic deformation, related to the breakup of Pangea, resulted in the formation of the Espino graben in the southernmost portion of the

Jaime Gonzalo Perez de Armas

2005-01-01

350

[Lipid and fatty acid profile of Perna viridis, green mussel (Mollusca: Bivalvia) in different areas of the Eastern Venezuela and the West Coast of Trinidad].  

PubMed

The species Perna viridis is a highly consumed species, which fast growth makes it an interesting aquaculture alternative for Venezuelan and Trinidad coasts. With the aim to contribute with its nutritional value information, this study analyzed lipid and fatty acid contents from samples taken in five locations from Eastern Venezuela and three from Trinidad West Coast. Total lipids were extracted and quantified, from a pooled sample of 100 organisms per location, by standard gravimetric methods, and their identification and quantification was done by TLC/FID (Iatroscan system). Furthermore, the esterified fatty acids of total lipid, phospholipids and triacylglycerols were identified and quantified by gas chromatography. Eastern Venezuela samples from Los Cedros, La Brea and Chaguaramas showed the highest total lipid values of 7.92, 7.74 and 7.53, respectively, and the minimum values were obtained for La Restinga (6.08%). Among lipid composition, Chacopata samples showed the lowest phospholipid concentration (48.86%) and the maximum values for cholesterol (38.87%) and triacylglycerols (12.26%); besides, La Esmeralda and Rio Caribe samples exhibited maximum phospholipids (88.71 and 84.93 respectively) and minimum cholesterol (6.50 and 4.42%) concentrations. Saturated fatty acids represented between 15.04% and 65.55% within total lipid extracts, with maximum and minimum values for La Esmeralda and Chacopata, respectively. Polyunsaturated results resulted between 7.80 and 37.18%, with higher values in La Brea and lower values in La Esmeralda. For phospholipids, saturated fatty acids concentrations varied between 38.81 and 48.68% for Chaguaramas and Chacopata samples, respectively. In the case of polyunsaturated fatty acids, these varied between non detected and 34.51%, with high concentrations in Los Cedros (27.97%) and Chaguaramas (34.51%) samples. For the triacylglycerols, the saturated fatty acids composition oscillated between 14.27 and 53.80% with low concentrations for Chacopata and high concentration for La Restinga; the polyunsaturated fatty acids were between 4.66 and 35.55% with lower values for Chacopata and higher values for Chaguaramas samples. P. viridis is recommended for human being consumption, according to the high content of unsaturated fatty acids found for this species. PMID:21516644

Koftayan, Tamar; Milano, Jahiro; D'Armas, Haydelba; Salazar, Gabriel

2011-03-01

351

CO{sub 2} emissions from developing countries: Better understanding the role of Energy in the long term. Volume 2, Argentina, Brazil, Mexico, and Venezuela  

SciTech Connect

Recent years have witnessed a growing recognition of the link between emissions of carbon dioxide (CO{sub 2}) and changes in the global climate. Of all anthropogenic activities, energy production and use generate the single largest portion of these greenhouse gases. Although developing countries currently account for a small share of global carbon emissions, their contribution is increasing rapidly. Due to the rapid expansion of energy demand in these nations, the developing world`s share in global modern energy use rose from 16 to 27 percent between 1970 and 1990. If the growth rates observed over the past 20 years persist energy demand in developing will surpass that in the countries of the Organization for Economic Cooperation and Development (OECD) early in the 21st century. The study seeks to examine the forces that galvanize the growth of energy use and carbon emissions, to assess the likely future levels of energy and CO{sub 2} in selected developing nations and to identify opportunities for restraining this growth. The purpose of this report is to provide the quantitative information needed to develop effective policy options, not to identify the options themselves. These individual studies were conducted fro Argentina, Brazil, Mexico and Venezuela in Latin America.

Ketoff, A.; Sathaye, J.; Goldman, N. [eds.

1991-07-01

352

Density estimates of the domestic vector of Chagas disease, Rhodnius prolixus St?l (Hemiptera: Reduviidae), in rural houses in Venezuela.  

PubMed Central

We reported the use of the timed manual method, routinely employed as an indicator to the relative abundance of domestic triatomine bugs, to estimate their absolute density in houses. A team of six people collected Rhodnius prolixus Stål bugs from the walls and roofs of 14 typical palm-leaf rural houses located in Cojedes, Venezuela, spending 40 minutes searching in each house. One day after these manual collections, all the houses were demolished and the number of triatomine bugs were identified by instar and counted. Linear regression analyses of the number of R. prolixus collected over 4 man-hours and the census counts obtained by house demolition indicated that the fit of the data by instar (stage II--adult) and place of capture (roof versus palm walls versus mud walls) was satisfactory. The slopes of the regressions were interpreted as a measure of "catchability" (probability of capture). Catchability increased with developmental stage (ranging from 11.2% in stage II to 38.7% in adults), probably reflecting the increasing size and visibility of bugs as they evolved. The catchability on palm wall was higher than that for roofs or mud walls, increasing form 1.3% and 3.0% in stage II to 13.4% and 14.0% in adults, respectively. We reported, also, regression equations for converting field estimates of timed manual collections of R. prolixus into absolute density estimates. Images Fig. 1

Rabinovich, J. E.; Gurtler, R. E.; Leal, J. A.; Feliciangeli, D.

1995-01-01

353

Light and desiccation responses of some Hymenophyllaceae (filmy ferns) from Trinidad, Venezuela and New Zealand: poikilohydry in a light-limited but low evaporation ecological niche  

PubMed Central

Background and Aims Hymenophyllaceae (filmy ferns) are typically plants of shady, constantly moist habitats. They attain greatest species diversity and biomass in humid tropical montane forests and temperate hyperoceanic climates. This paper presents ecophysiological data bearing on their worldwide ecological niche space and its limits. Methods Chlorophyll fluorescence was used to monitor recovery in desiccation experiments, and for measurements of 95 % saturating irradiance [photosynthetic photon flux density (PPFD95 %)] of photosynthetic electron flow and other parameters, in the New Zealand Hymenophyllum sanguinolentum, and three species each of Hymenophyllum and Trichomanes from forests in Trinidad and Venezuela. Key Results Hymenophyllum sanguinolentum was comparable in desiccation tolerance and light responses with the European species. The more common species in the two tropical forests showed PPFD95 % >100 µmol m?2 s?1, and withstood moderate desiccation (–40 MPa) for several days. The four most shade-adapted species had PPFD95 % ?51 µmol m?2 s?1, and were sensitive to even mild and brief desiccation (–22 MPa for 3 d). Conclusions Light and desiccation responses of filmy ferns can be seen as an integrated package. At low light and windspeed in humid forests, net radiation and saturation deficit are low, and diffusion resistance high. Water loss is slow and can be supported by modest conduction from the sub-stratum. With higher irradiance, selection pressure for desiccation tolerance increases progressively. With low light and high humidity, the filmy fern pattern of adaptation is probably optimal, and the vascular plant leaf with mesophyll and stomata offers no advantage in light capture, water economy or CO2 uptake. Trade-offs between light adaptation and desiccation tolerance, and between stem conduction and water absorption through the leaf surface, underlie adaptive radiation and niche differentiation of species within the family. Hymenophyllaceae are a rare example of an evolutionary shift of adaptive strategy from typical vascular plant adaptation to the poikilohydry most typical of bryophytes.

Proctor, Michael C. F.

2012-01-01

354

The structural basis for substrate anchoring, active site selectivity, and product formation by P450 PikC from Streptomyces venezuelae.  

PubMed

The pikromycin (Pik)/methymycin biosynthetic pathway of Streptomyces venezuelae represents a valuable system for dissecting the fundamental mechanisms of modular polyketide biosynthesis, aminodeoxysugar assembly, glycosyltransfer, and hydroxylation leading to the production of a series of macrolide antibiotics, including the natural ketolides narbomycin and pikromycin. In this study, we describe four x-ray crystal structures and allied functional studies for PikC, the remarkable P450 monooxygenase responsible for production of a number of related macrolide products from the Pik pathway. The results provide important new insights into the structural basis for the C10/C12 and C12/C14 hydroxylation patterns for the 12-(YC-17) and 14-membered ring (narbomycin) macrolides, respectively. This includes two different ligand-free structures in an asymmetric unit (resolution 2.1 A) and two co-crystal structures with bound endogenous substrates YC-17 (resolution 2.35 A)or narbomycin (resolution 1.7 A). A central feature of the enzyme-substrate interaction involves anchoring of the desosamine residue in two alternative binding pockets based on a series of distinct amino acid residues that form a salt bridge and a hydrogen-bonding network with the deoxysugar C3' dimethylamino group. Functional significance of the salt bridge was corroborated by site-directed mutagenesis that revealed a key role for Glu-94 in YC-17 binding and Glu-85 for narbomycin binding. Taken together, the x-ray structure analysis, site-directed mutagenesis, and corresponding product distribution studies reveal that PikC substrate tolerance and product diversity result from a combination of alternative anchoring modes rather than an induced fit mechanism. PMID:16825192

Sherman, David H; Li, Shengying; Yermalitskaya, Liudmila V; Kim, Youngchang; Smith, Jarrod A; Waterman, Michael R; Podust, Larissa M

2006-07-06

355

The Structural Basis for Substrate Anchoring, Active Site Selectivity, and Product Formation by P450 PikC from Streptomyces venezuelae  

PubMed Central

The pikromycin (Pik)/methymycin biosynthetic pathway of Streptomyces venezuelae represents a valuable system for dissecting the fundamental mechanisms of modular polyketide biosynthesis, aminodeoxysugar assembly, glycosyltransfer, and hydroxylation leading to the production of a series of macrolide antibiotics, including the natural ketolides narbomycin and pikromycin. In this study, we describe four x-ray crystal structures and allied functional studies for PikC, the remarkable P450 monooxygenase responsible for production of a number of related macrolide products from the Pik pathway. The results provide important new insights into the structural basis for the C10/C12, and C12/C14 hydroxylation patterns for the 12- (YC-17) and 14-membered ring (narbomycin) macrolides, respectively. This includes two different ligand-free structures in an asymmetric unit (resolution 2.1 Å) and two co-crystal structures with bound endogenous substrates YC-17 (resolution 2.35 Å) or narbomycin (resolution 1.7 Å). A central feature of the enzyme-substrate interaction involves anchoring of the desosamine residue in two alternative binding pockets based on a series of distinct amino acid residues that form a salt bridge and a hydrogen bonding network with the deoxysugar C3? dimethylamino group. Functional significance of the salt bridge was corroborated by site-directed mutagenesis that revealed a key role for E94 in YC-17 binding, and E85 for narbomycin binding. Taken together, the x-ray structure analysis, site-directed mutagenesis and corresponding product distribution studies reveal that PikC substrate tolerance, and product diversity result from a combination of alternative anchoring modes, rather than an induced fit mechanism.

Sherman, David H.; Li, Shengying; Yermalitskaya, Liudmila V.; Kim, Youngchang; Smith, Jarrod A.; Waterman, Michael R.; Podust, Larissa M.

2010-01-01

356

Fluvial geochemistry of the eastern slope of the northeastern Andes and its foredeep in the drainage of the Orinoco in Colombia and Venezuela  

NASA Astrophysics Data System (ADS)

The fluvial geochemistry of the tributaries of the Orinoco draining the eastern branch of the northern Andes in Colombia and Venezuela is determined by lithology and ranges from rivers dominated by aluminosilicate weathering, mainly of shales and mafic rocks, to those bearing the signatures of dissolution of marine limestones and evaporites and of continental playa deposits. These left bank tributaries of the Orinoco provide the overwhelming proportion of the suspended and dissolved loads transported by the main stem although feeding only half the discharge. However, due to the extreme severity of weathering on the Guayana Shield, the right bank tributaries supply about half the silica and 40% of the K carried by the Orinoco. There is a similar partitioning between the Andes and the lowlands in the Amazon drainage. In contrast the Mackenzie, which drains the northern extremity of the continental arc of the Western Americas, is completely dominated by the weathering of limestones and evaporites and transports very little silica. This, again, appears to be a reflection of lithology since the Yukon, in similar latitudes and terrain, has silica concentrations comparable to the Tropical systems. In addition, a conservative deconvolution of the data gives estimates of the net consumption of atmospheric CO 2 by aluminosilicate weathering that follows the same pattern. Thus, the available evidence from the Western Americas indicates that exposure and lithology, rather than the climatic variables, temperature, and runoff, dominate the weathering yields in active orogenic belts. These observations contradict the conventional view of weathering processes and their controls and are at complete variance with the assumptions parameterised in most models of the geochemical cycle.

Edmond, J. M.; Palmer, M. R.; Measures, C. I.; Brown, E. T.; Huh, Y.

1996-08-01

357

Three-Dimensional Structure of DesVI from Streptomyces venezuelae: A Sugar N,N-Dimethyltransferase Required for dTDP-Desosamine Biosynthesis  

SciTech Connect

d-Desosamine, or 3-(dimethylamino)-3,4,6-trideoxyglucose, is an unusual sugar found on the macrolide antibiotic erythromycin, and it has been shown to play a critical role in the biological activity of the drug. Desosamine is added to the parent aglycone via the action of a glycosyltransferase that utilizes dTDP-desosamine as its substrate. Six enzymes are required for the biosynthesis of dTDP-desosamine in Streptomyces venezuelae, with the last step catalyzed by DesVI, an N,N-dimethyltransferase. Here we describe the X-ray crystal structure determined to 2.0 {angstrom} resolution of DesVI complexed with S-adenosylmethionine (SAM) and the substrate analogue UDP-benzene. Each subunit of the DesVI dimer contains a seven-stranded mixed {beta}-sheet flanked on either side by {alpha}-helices. In addition to this major tertiary structural element, there is a four-stranded antiparallel {beta}-sheet that provides the platform necessary for subunit-subunit assembly. On the basis of the UDP-benzene binding mode, the DesVI substrate, dTDP-3-(methylamino)-3,4,6-trideoxyglucose, has been modeled into the active site. This model places the C-6' methyl group of the sugar into a hydrophobic patch that is well-conserved among putative nucleotide-linked sugar dimethyltransferases. It is formed by Trp 140, Met 178, and Ile 200. The sugar C-2' hydroxyl sits near Tyr 14, and its C-3' amino group is properly positioned for direct in-line attack of the cofactor's reactive methyl group. While methyltransferases that catalyze single alkylations at carbons, oxygens, sulfurs, and nitrogens have been well characterized, little is known regarding enzymes capable of N,N-dimethylation reactions. As such, the ternary structure of DesVI reported here serves as a structural paradigm for a new family of dimethyltransferases that function on nucleotide-linked sugars.

Burgie, E. Sethe; Holden, Hazel M. (UW)

2008-07-28

358

Trends of violence among 7th, 8th and 9th grade students in the state of Lara, Venezuela: The Global School Health Survey 2004 and 2008  

PubMed Central

Background Violence by young people is one of the most visible forms of violence and contributes greatly to the global burden of premature death, injury and disability. Methods The Global School-based Student Health Survey (GSHS), State of Lara, Venezuela (GSHS-Lara) is a school-based surveillance system. It comprises a repeated, cross-sectional, self-administered survey drawn from a representative sample of 7th to 9th grade students, performed in the school years 2003-2004 (GSHS-Lara 2004) and 2007-2008 (GSHS-Lara 2008). It explores, among other things, a general violence indicator such as school absenteeism due to feeling unsafe at school or on the way to or from school for any reason; and more specific indicators of violence such as robbery, bullying, physical fights and use of weapons, as well as exposure to lectures on how to prevent violence. Results are given in terms of prevalence percentage. Results Absenteeism doubled between the two study periods (10.8% to 20.8%). The number of students that were a victim of robbery remained high and without change both outside (14.2% and 14.8%) and inside school (21.7% and 22.0%). The number of victims of bullying was high and increasing (33.4% and 43.6%). Bullying associated with being physically attacked decreased (18.5% to 14.3%). Physical attacks without active participation and not associated with bullying were frequent (21.5%). Physical fighting with active participation prevalence remained high and without change (27.5% and 28.2%). Carrying a weapon almost doubled (4.3% to 7.1%). Less than 65% reported classes for violence prevention. Conclusions The GSHS-Lara shows that violence is an important public health problem that needs to be addressed by the community and its authorities.

2011-01-01

359

Children live, feel, and respond to experiences of food insecurity that compromise their development and weight status in peri-urban Venezuela.  

PubMed

Children's experiences of food insecurity (FI) may be conceptually distinct and different from those of adults. Previous study of children's experiences of FI has relied primarily on their parents' perspective. This study explored, described, and conceptualized experiences of FI in children attending 5 public schools in peri-urban areas of the Miranda State, Venezuela, South America using a naturalistic approach. Children aged 10-17 y were studied through focus groups (n = 42) and individual interviews (n = 13). Interviews were recorded, transcribed, and analyzed using grounded theory. Children were cognitively aware of FI, worry in their parents, and causes both external and internal to their households. Children were also emotionally aware of FI, with feelings of concern, anguish, and sadness, and manifestations such as crying. Children reported being physically hungry, experiencing reduced quantity and quality of food intake, having smaller meals, and recognizing thinness and fainting as consequences. Children's responses to FI included reduction of quality and quantity of food, child labor, sacrifice in food consumption, food from waste, support from extended family members, and strategies for purchasing, acquiring, preparing, and cooking food. Children were not always protected, especially when the head of the family was unemployed, had drug-alcohol problems, or was extremely poor. Protection could come from parents to children and from older children to parents and younger children. Children should have certain access to food that is dignified, timely, efficient, and adequate in harmonious social conditions to prevent and resolve situations that compromise their physical, cognitive, and socio-emotional well-being. PMID:22623397

Bernal, Jennifer; Frongillo, Edward A; Herrera, Héctor; Rivera, Juan

2012-05-23

360

Oral transmission of Chagas disease: typing of Trypanosoma cruzi from five outbreaks occurred in Venezuela shows multiclonal and common infections in patients, vectors and reservoirs.  

PubMed

In Venezuela six episodes of oral transmission of Chagas disease (OChD) have been described, being the one reported in 2007 with a total of 103 people infected the largest worldwide. This work shows the use of three molecular markers (mini-exon gene and domains 24S? and 18S of the ribosomal RNA) to characterize the infecting Trypanosoma cruzi strain of patients, reservoirs and vectors involved in five of the six OChD outbreaks. For this, 28 T. cruzi isolates were characterized by PCR, and the products of these reactions cloned and sequenced to reveal the existence of different TcI SL-IR genotypes. We also describe a new PCR assay able to discriminate between TcIb and TcId parasite populations. In summary, we have identified mostly parasites with the TcId haplotype and multiclonal populations with predominance of haplotype TcId (65.2%). Additionally, populations of haplotypes TcIb, TcIa and mixtures (TcId+TcIb, TcId+TcIa, TcIb+TcIa) are recurrent in samples obtained from children. The analysis of the SL-IR motif showed two clones depicting a different motif that could be an evidence for a possible hybrid haplotype between TcIa and TcIb (haplotype TcIa/Ib). Interestingly, in a single patient haplotype differences between T.cruzi isolates obtained pre and post-treatment were found. In conclusion, our findings show that in order to understand the pathogenic mechanisms involved in the orally acquired Chagas disease there is a need to join efforts to study T. cruzi haplotypes, their tissue tropisms and their susceptibility to chemoteraphy. PMID:23567816

Muñoz-Calderón, A; Díaz-Bello, Z; Valladares, B; Noya, O; López, M C; Alarcón de Noya, B; Thomas, M C

2013-04-06

361

[Scorpionfish (Scorpaena plumieri) envenomation in a fishing and turistic community of Paraguaná peninsula, Falcón state, Venezuela: clinical, epidemiological and treatment aspects].  

PubMed

Thirty six patients apparently envenomed by the scorpion fish Scorpaena plumieri, consulting to the ambulatory emergency of a fishing and turistic town Adícora, state Falcón, Venezuela, from December 2006 to April 2007, allowed us to carry out a descriptive analysis of the clinical, epidemiology and treatment of this envenoming. Envenomation percentages were not significantly different between sex or age (X2=0.03, p= 0.758; X2=0.06; p=0.81, respectively). Most of the accidents occurred in february and april (> 50%), in the afternoon (83.33%) when individuals were bathing or swimming at the beach (97.22%), suggesting a seasonal pattern. The time between ambulatory medical assistance and the accident varied from 3 to 30 minutes, with a mean time of 5.97 +/- 4.39. The cutting injuries were located at the feet in all patients, with 0.2 to 3 cm (X=1.04 +/- 0.86) of length and between 1 to 2 mm of width. Clinical manifestations observed were: intense and irradiated pain (100%) (VAS=X: 9.39 +/- 0.60), edema (27.78%) and erythema (22.22%). One case had systemic manifestations: hypotension and faintness. Treatment consisted of infiltration with lidocaine (1%), systemic anti-inflmatory-analgesia (100 mg, orally every 8 hours for 5 days) and antibiotic therapy per os (500 mg, 2 daily dose for 10 days). All patients had a satisfactory post-treatment evolution, between 5 to 120 (X=30.11 +/- 33.30) minutes, with a pain VAS mean values significantly lower (0.72 +/- 0.62; t=52.2, p=0.0001). PMID:18846771

Loyo, Jesús; Lugo, Lusneida; Cazorla, Dalmiro; Acosta, María Eugenia

2008-09-01

362

High prevalence of asthma symptoms in Warao Amerindian children in Venezuela is significantly associated with open-fire cooking: a cross-sectional observational study  

PubMed Central

Background The International Study on Asthma and Allergies in Childhood (ISAAC) reported a prevalence of asthma symptoms in 17 centers in nine Latin American countries that was similar to prevalence rates reported in non-tropical countries. It has been proposed that the continuous exposure to infectious diseases in rural populations residing in tropical areas leads to a relatively low prevalence of asthma symptoms. As almost a quarter of Latin American people live in rural tropical areas, the encountered high prevalence of asthma symptoms is remarkable. Wood smoke exposure and environmental tobacco smoke have been identified as possible risk factors for having asthma symptoms. Methods We performed a cross-sectional observational study from June 1, 2012 to September 30, 2012 in which we interviewed parents and guardians of Warao Amerindian children from Venezuela. Asthma symptoms were defined according to the ISAAC definition as self-reported wheezing in the last 12 months. The associations between wood smoke exposure and environmental tobacco smoke and the prevalence of asthma symptoms were calculated by means of univariate and multivariable logistic regression analyses. Results We included 630 children between two and ten years of age. Asthma symptoms were recorded in 164 of these children (26%). The prevalence of asthma symptoms was associated with the cooking method. Children exposed to the smoke produced by cooking on open wood fires were at higher risk of having asthma symptoms compared to children exposed to cooking with gas (AOR 2.12, 95% CI 1.18 - 3.84). Four percent of the children lived in a household where more than ten cigarettes were smoked per day and they had a higher risk of having asthma symptoms compared to children who were not exposed to cigarette smoke (AOR 2.69, 95% CI 1.11 - 6.48). Conclusion Our findings suggest that children living in rural settings in a household where wood is used for cooking or where more than ten cigarettes are smoked daily have a higher risk of having asthma symptoms.

2013-01-01

363

Snake venomics and antivenomics of Bothrops colombiensis, a medically important pitviper of the Bothrops atrox-asper complex endemic to Venezuela: Contributing to its taxonomy and snakebite management.  

PubMed

The taxonomic status of the medically important pitviper of the Bothrops atrox-asper complex endemic to Venezuela, which has been classified as Bothrops colombiensis, remains incertae cedis. To help resolving this question, the venom proteome of B. colombiensis was characterized by reverse-phase HPLC fractionation followed by analysis of each chromatographic fraction by SDS-PAGE, N-terminal sequencing, MALDI-TOF mass fingerprinting, and collision-induced dissociation tandem mass spectrometry of tryptic peptides. The venom contained proteins belonging to 8 types of families. PI Zn(2+)-metalloproteinases and K49 PLA(2) molecules comprise over 65% of the venom proteins. Other venom protein families comprised PIII Zn(2+)-metalloproteinases (11.3%), D49 PLA(2)s (10.2%), l-amino acid oxidase (5.7%), the medium-sized disintegrin colombistatin (5.6%), serine proteinases (1%), bradykinin-potentiating peptides (0.8%), a DC-fragment (0.5%), and a CRISP protein (0.1%). A comparison of the venom proteomes of B. colombiensis and B. atrox did not support the suggested synonymy between these two species. The closest homologues to B. colombiensis venom proteins appeared to be toxins from B. asper. A rough estimation of the similarity between the venoms of B. colombiensis and B. asper indicated that these species share approximately 65-70% of their venom proteomes. The close kinship of B. colombiensis and B. asper points at the ancestor of B. colombiensis as the founding Central American B. asper ancestor. This finding may be relevant for reconstructing the natural history and cladogenesis of Bothrops. Further, the virtually indistinguishable immunological crossreactivity of a Venezuelan ABC antiserum (raised against a mixture of B. colombiensis and Crotalus durissus cumanensis venoms) and the Costa Rican ICP polyvalent antivenom (generated against a mixture of B. asper, Crotalus simus, and Lachesis stenophrys venoms) towards the venoms of B. colombiensis and B. asper, supports this view and suggests the possibility of indistinctly using these antivenoms for the management of snakebites by any of these Bothrops species. However, our analyses also evidenced the limited recognition capability or avidity of these antivenoms towards a number of B. colombiensis and B. asper venom components, most notably medium-size disintegrins, bradykinin-potentiating peptides, PLA(2) proteins, and PI Zn(2+)-metalloproteinases. PMID:19457355

Calvete, Juan J; Borges, Adolfo; Segura, Alvaro; Flores-Díaz, Marietta; Alape-Girón, Alberto; Gutiérrez, José María; Diez, Nardy; De Sousa, Leonardo; Kiriakos, Demetrio; Sánchez, Eladio; Faks, José G; Escolano, José; Sanz, Libia

2009-01-16

364

[Growth and survival of the green mussel P. viridis (Bivalvia: Mytilidae) in bottom culture conditions in Turpialito, Golfo de Cariaco, Venezuela].  

PubMed

Mussels represent one of the most important mollusk species for culture activities around the world, and their growth may depend on the culture system used and locality. In this study, we evaluated the growth of Perna viridis in bottom culture to test its performance when using natural food, and to decide its use as a culture species in the Gulf of Cariaco. For this, mussel seeds (35.81 +/- 1.41 mm in length) were obtained in the locality of Guaca (North coast of Sucre state) and transferred to the Hydrobiological Station of Turpialito, Gulf of Cariaco, Sucre state, Venezuela, where they were planted in "Spanish baskets" to evaluate their growth between July 2007 and February 2008. Monthly survival was determined and the maximum shell length, dry mass of muscle and remains tissues of the gonad. The environmental parameters (water temperature, salinity, dissolved oxygen, chlorophyll a, total seston and organic fraction), in the cultivation area were determined every 15 days. Monthly measurements were made of proteins, lipids and carbohydrates to seston. During the entire study the mussels showed continued growth, ultimately reaching a maximum length of 78.7 +/- 4.43 mm. However, the growth rate of the dry mass of somatic (muscle, other tissue) and reproductive tissues showed variability throughout the study, and observed a significant increase by the end of the experiment. The observed variations in the growth rate of the reproductive tissue mass depended on the reserves accumulated and food offered by the environment. The organic seston throughout the experience showed an independence of temperature and chlorophyll a values; this one maintained values above 1 mg/L, thus forming the main food resource for mussels. The high content of proteins, lipids and carbohydrates observed in the seston at the end of the study, might be mainly associated with coastal upwelling, which provides a great food contribution of phytoplankton and organic type. The high survival rate (>80%), increase in the length of the shell and the high gonad production, suggests an excellent physiological condition of P. viridis, related to the availability and quality of food particularly the organic type present in the medium. We concluded that the bottom culture can provide an alternative aquaculture production in the Gulf of Cariaco. PMID:23342526

Acosta, Vanessa; Montes, Marbelis; Cortez, Roraysi; Guevara, Miguel; Lodeiros, César

2012-12-01

365

Tectonic and thermal history of the western Serrania del Interior foreland fold and thrust belt and Guarico Basin, north central Venezuela: Implications of new apatite fission track analysis and seismic interpretation  

NASA Astrophysics Data System (ADS)

Structural analysis, interpretation of seismic reflection lines, and apatite fission-track analysis in the Western Serrania del Interior fold and thrust belt and in the Guarico basin of north-central Venezuela indicate that the area underwent Mesozoic and Tertiary-to-Recent deformation. Mesozoic deformation, related to the breakup of Pangea, resulted in the formation of the Espino graben in the southernmost portion of the Guarico basin and in the formation of the Proto-Caribbean lithosphere between the diverging North and South American plates. The northern margin of Venezuela became a northward facing passive margin. Minor normal faults formed in the Guarico basin. The most intense deformation took place in the Neogene when the Leeward Antilles volcanic island arc collided obliquely with South America. The inception of the basal foredeep unconformity in the Late Eocene-Early Oligocene marks the formation of a perisutural basin on top of a buried graben system. It is coeval with minor extension and possible reactivation of Cretaceous normal faults in the Guarico basin. It marks the deepening of the foredeep. Cooling ages derived from apatite fission-tracks suggest that the obduction of the fold and thrust belt in the study area occurred in the Late Oligocene through the Middle Miocene. Field data and seismic interpretations suggest also that contractional deformation began during the Neogene, and specifically during the Miocene. The most surprising results of the detrital apatite fission-track study are the ages acquired in the sedimentary rocks of the easternmost part of the study area in the foreland fold and thrust belt. They indicate an Eocene thermal event. This event may be related to the Eocene NW-SE convergence of the North and South American plates that must have caused the Proto-Caribbean lithosphere to be shortened. This event is not related to the collision of the arc with South America, as the arc was far to the west during the Eocene.

Perez de Armas, Jaime Gonzalo

366

Fisheries Report for Venezuela 1983.  

National Technical Information Service (NTIS)

Venezuelan fishermen caught 213,000 metric tons (t) of fish and shellfish in 1982, a 10 percent increase from the 193,000 t taken in 1981. The increase was primarily due to improved sardine catches. Shrimp fishermen, however, reported a disappointing year...

E. Hansen

1983-01-01

367

Modellazione del legame costitutivo di isolatori in gomma armata e studio delle conseguenze sulla risposta sismica di strutture isolate. (Reinforced rubber bearing behaviour modeling; isolated structure seismic response).  

National Technical Information Service (NTIS)

In this analysis of simplified constitutive models suitable for the simulation of high damping rubber bearings (for use in nuclear and industrial plants), the well-known equivalent elastic and bilinear models are compared with the Davidenkov-Martin model ...

T. Sano' G. Di Pasquale

1990-01-01

368

Interpretacion de Fotografias Aereas para la Clasificacion y Elaboracion de Cartas Geograficas del Suelo (Interpretation of Photographs for the Classification and Production of Geographic Soil Maps).  

National Technical Information Service (NTIS)

Since 1929, aerial photography has been a boon to soil mapping, both as a check on field studies, and as a temporary and partial substitute for them when necessary. When the latter situation is the case, the proper photographs and interpretation of them i...

1971-01-01

369

Education in Venezuela. Bulletin, 1948, No. 14  

ERIC Educational Resources Information Center

|The Office of Education has undertaken the preparation of a series of basic studies on education in a number of Central and South American countries under the sponsorship of the Interdepartmental Committee on Cultural and Scientific Cooperation. This series of studies is part of a program to promote understanding of educational conditions in the…

Goetz, Delia

1948-01-01

370

Cryptococcus neoformans, Cryptococcus gattii: serotypes in Venezuela.  

PubMed

Cryptococcus neoformans is one of the medically important yeast-like fungi. C. neoformans var. gatti has been made a species: C. gatti. In our country, there are few studies about these two species and their serotypes. The aim of this study was to determine the distribution of C. neoformans and C. gattii, and their serotypes in Venezuelan clinical isolates. One hundred and twenty C. neoformans and 12 C. gattii clinical isolates were identified by L-canavanine, glycine, and bromothymol blue agar media (CGB). These were investigated by agglutination and adsorption studies with anticryptococcal sera, which were produced by rabbit immunization. Of the 132 isolates 59.8% were typed serotype A (C. neoformans), followed by 25.8% serotype D (C. neoformans), 5.3% serotype AD (C. neoformans), and 5.3% were typed serotype C (var. gattii). Additionally 3.8% were serotype B (C. gattii). PMID:18512129

Pérez, C; Dolande, M; Moya, M; Roselló, A; de Capriles, Claudia R Hartung; Landaeta, M E; Mata-Essayag, S

2008-05-30

371

Pleasure Travel Market to North America: Venezuela.  

National Technical Information Service (NTIS)

The objectives of the study are: To provide broad-based marketing information on the Venezuelan long haul pleasure travel market for strategic planning purposes; To identify and describe Venezuelan travel segments that are prime targets for travel to Cana...

1991-01-01

372

Mara Field, a unique giant in Venezuela  

Microsoft Academic Search

The Mara field is located in Venzuela, 45 km northwest of Maracaibo, on the Mara-La Paz anticlinal trend. Discovered in 1945 by the Caribbean Petroleum Co. (Shell group), the field has produced 407 MMB as of 1991 and has remaining proven reserves of 60 MMB, and probable and possible reserves of 58 MMB, for an ultimate potential recovery of 525

1993-01-01

373

Hearing-Impaired Children in Venezuela: 1985.  

ERIC Educational Resources Information Center

|The 1984-85 Venezuelan Survey of Deaf Children collected information on 804 deaf students between ages 3 and 14. Among findings were that 29% of the cases were caused by maternal rubella, that 36% had additional handicaps, and that meningitis was the most frequently reported after-birth cause of hearing losses. (Author/DB)|

Schildroth, Arthur; And Others

1987-01-01

374

Corruption and business in present day Venezuela  

Microsoft Academic Search

Venezuelan media present corruption as a major problem of the country and a research conducted by the author shows managers perceive it as business ethics' main issue. The corruption type addressed to in this article is the collusion between public officials and private managers for illegal or undue profits. Corruption in this form is related to the long-standing policy of

Rogelio Perez Perdomo

1990-01-01

375

Household Consumer Goods (Venezuela). Housewares, September 1991.  

National Technical Information Service (NTIS)

A subsector in which subjective factors are highly influential in final market figures, household utensils and tableware comprises a most important part of the Venezuelan consumer buying world. The lowering of import duties as part of the government's ong...

1991-01-01

376

THE DIET OF THE OILBIRD IN VENEZUELA  

Microsoft Academic Search

o The Oilbird {Steatornis caripensis) is a nocturnal frugivore that breeds and roosts in caves in forested areas from Trinidad through to Peru and Bolivia. We have studied the diet of a colony of Oilbirds in north-eastern Vene- zuela {Caripe, Monagas State), from July 1985 to January 1988, emphasizing the species composition of the fruit plants utilized, seasonality of fruit

Carlos Bosque; Rudyard Ramírez; Domingo Rodríguez

1995-01-01

377

Hearing-Impaired Children in Venezuela: 1985.  

ERIC Educational Resources Information Center

The 1984-85 Venezuelan Survey of Deaf Children collected information on 804 deaf students between ages 3 and 14. Among findings were that 29% of the cases were caused by maternal rubella, that 36% had additional handicaps, and that meningitis was the most frequently reported after-birth cause of hearing losses. (Author/DB)

Schildroth, Arthur; And Others

1987-01-01

378

Caracas, Venezuela, Site Effect Determination with Microtremors  

NASA Astrophysics Data System (ADS)

- Caracas 1967 earthquake caused heavy damage to multi-story buildings. In 1995, 184 microtremor measurement points were performed over the city. The measurement grid was more or less dense and covered the main part of the alluvial basin as well as surrounding rock basement. For each point, the horizontal record spectrum was divided by the vertical one (H/V ratio). Subsequently, the strongest value (Ao) of this ratio in a given frequency band was kept, as well as the frequency (Fo) where it occurred. Spatial interpolations of Ao and Fo were performed among all points of Palos Grandes district. A map was plotted representing a single surface where Ao is relief and Fo is represented by grey gradation. An alluvion thickness (H) map can be compared with this result. Damaged buildings are located on the same map. Fo decreases until 0.6Hz when alluvion thickness (H) increases. Fo values fit with frequencies previously predicted from computation and with 1967 earthquake observations. Moreover, interpolation surfaces show that amplification (Ao) of H/V on microtremor is quite low above rock but is high on the south part of the basin. The maximum occurs over the non-urbanized zone. However the other area, where Ao is higher than 5, roughly corresponds to the location of the four collapsed buildings. Furthermore, the estimated natural frequency of these buildings was around Fo. Graphics showing H, Fo and Ao evolution through the basin were composed. Links between all these values are noticeable. Fo is claimed to be very similar to the resonance frequency of soil. As for Ao, it could be a fairly relevant sign of damage seriousness. Microtremor technique is an economic tool and it allows measurement grid as dense as desired. H/V ratio processing followed by interpolation of maximum values provides precise and useful information about expected site effect.

Duval, A.-M.; Vidal, S.; Méneroud, J.-P.; Singer, A.; De Santis, F.; Ramos, C.; Romero, G.; Rodriguez, R.; Pernia, A.; Reyes, N.; Griman, C.

379

Freed from Illiteracy? A Closer Look at Venezuela’s Robinson Literacy Campaign  

Microsoft Academic Search

We evaluate the success of the Venezuelan government’s latest nationwide literacy program, Misión Robinson, using official Venezuelan government survey data. Controlling for existing trends in literacy rates by age groups over the period 1975 to 2005, we find at most a small positive effect of Robinson on literacy rates, and in many specifications the program impact is statistically indistinguishable from

Daniel Ortega; Francisco Rodríguez; Edward Miguel

2006-01-01

380

Hypertension and cardiovascular health in Venezuela and Latin American countries  

Microsoft Academic Search

Since 1950 all countries of the Latin-American sub-continent have experienced very important changes in several health indicators, in the demographic, epidemiological, socio-cultural and way of living profiles. The proportion of the population over 65 years old tend to be low in the Latin American countries in contrast to developed countries. Cardiovascular diseases are the main cause of death in most

R Hernández-Hernández; MC Armas-Padilla; MJ Armas-Hernández; M Velasco; Rafael Hernández Hernández

2000-01-01

381

Methane emissions from the Orinoco River floodplain, Venezuela  

Microsoft Academic Search

Methane emissions were measured over a 17-month interval at 21 locations on the Orinoco fringing floodplain and upper delta (total area, 14,000 km 2). Emissions totaled 0.17 Tg yr 1, or 7.1 mmol d 1 (114 mg d 1; standard deviation,18%) per m2 of water surface. Ebullition accounted for 65% of emissions. Emission rates were about five times as high

LESLEY K. SMITH; WILLIAM M. LEWIS; JEFFREY P. CHANTON; GREG CRONIN; STEPHEN K. HAMILTON

2000-01-01

382

An El Jobo Mastodon Kill at Taima-taima, Venezuela  

Microsoft Academic Search

Excavation at Taima-taima in 1976 recovered artifacts of the El Jobo complex in direct association with the butchered remains of a juvenile mastodon. Radiocarbon dates on associated wood twigs indicate a minimum age of 13,000 years before the present for the mastodon kill, a dating significantly older than that of the Clovis complex in North America. The El Jobo complex

Alan L. Bryan; Rodolfo M. Casamiquela; Jose M. Cruxent; Ruth Gruhn; Claudio Ochsenius

1978-01-01

383

The United States Congress and Venezuela's Hugo Chavez  

Microsoft Academic Search

The Soviet Union's dissolution in December 1991 marks the end of the Cold War and the elimination of the United States' main rival for global political-economic leadership. For decades U.S. foreign policymakers had formulated policies aimed at containing the spread of Soviet communism and Moscow's interventionist policies in the Americas. They now assumed that Latin American leftist revolutionary upheavals could

Mariano J Beillard

2009-01-01

384

Sur Lago area, Venezuela: Three dimensional integrated seismic interpretation  

Microsoft Academic Search

In 1988, 550 square km of 3D seismic data were acquired in the Sur Del Lago area. The aims of the survey were (1) To better define structures already identified from the existing 1 [times] 1 km 2D seismic grid at the level of potential Cretaceous limestone reservoirs and (2) To further study the prospectivity of potential structural and stratigraphic

A. Growcott; A. McIan; R. Ramirez

1993-01-01

385

Ceuta area, Lake Maracaibo, Venezuela. 3D integrates seismic interpretation  

Microsoft Academic Search

Maraven S.A. is currently carrying out an aggressive 3D acquisition campaign in the Lake Maracaibo area. Data will be and has been recorded to totally cover the Maraven exploration and production acreage. To further understand the complex tectonics of the Ceuta area a new 3D seismic interpretation has led to a revision of the structural model. The current model envisages

E. Ramirez; A. McIan

1993-01-01

386

Geology and geomorphology of the Roraima group, southeastern Venezuela  

NASA Astrophysics Data System (ADS)

A moderately detailed, accurate geologic geomorphologic map of the Roraima region at a 1:250,000 scale was prepared. This provides a suitable base for future, more detailed studies. It is recommended that the Roraima Formation be raised to Group status and include three apparently conformable but lithogically separable Formations from the base upwards, these are the Canaima, Gualaquinima, and Auyantepui formation. Two composite stratigraphic sections are established and formational thicknesses determined near Santa Elena de U. and Canaima. Radar imagery and aerial photo interpretation allows improved mapping of regional and local structures. Broad, gentle, postdepositional folding of the Roraima into anteclises and syneclises apparently was followed by intrusion of basic dikes and sills; the principal host is the Canaima Formation. Diamond bearing places in the present alluvial valleys are the result of continuous deposition, reworking and redeposition of older, more geographically disjunct floodplain and deltaic sediments.

Yanezpintado, G.

387

Structural interpretation along the Icotea Fault, Lake Maracaibo, Venezuela  

SciTech Connect

This structural interpretation, performed on an interactive workstation, corresponds to an area covered by three 3D seismic surveys in Lake Maracaibo. These surveys (Block I, Northern and Southern Lama) focus on the Icotea fault trend, which is one of the major structural features in the Maracaibo Basin. The present study is centered on the interpretation of the origin and evolution of this fault trend. The Maracaibo Basin evolved from an initial phase dominated by extensional tectonism to a later compressional phase. The Icotea fault is interpreted as the border of a Triassic-Jurassic half graben. Subsequent to the deposition of shelf sediments, the fault became reactivated during the Paleocene and Lower to Middle Eocene. During the change to compressional tectonics within the upper Eocene, the half graben became inverted. As an associated event during the structural inversion, a sinistral strike slip deformation took place along the fault. The latest stage of faulting developed during Miocene, and resulted in lateral offsets along the Icotea fault system.

Bueno, E.; Zubizarreta, J.; Pinto, J.; Taylor, C.; Prieto, E. (Maraven, S.A., Caracus (Venezuela))

1993-02-01

388

Mass Schooling for Socialist Transformation in Cuba and Venezuela  

ERIC Educational Resources Information Center

In contemporary contexts of Education for All and emphases on national educational performance, mass education globally continues to be strongly informed by human capital thinking, and by notions of developing future world citizens and workers for the international economy. In this paper, our central focus is on the ongoing educational project of…

Griffiths, Tom G.; Williams, Jo

2009-01-01

389

Physiographic Sections of the Guiana Highlands, Venezuela and Guyana.  

National Technical Information Service (NTIS)

This report discusses the nature of the Guiana Shield and delimits meaningful subdivisions. The Shield contains the Guiana Lowlands, Guiana Hills, and Guiana Highlands, all physiographic provinces. To subdivide the Guiana Highlands into smaller units the ...

C. L. Smith

1976-01-01

390

Fracture conductivity: the most important characteristic in fracturing. [Venezuela  

Microsoft Academic Search

A vital step toward obtaining highly conductive fractures is the selection of a proper and adequate propping agent. Creole Petroleum Corp. has found, from experience in fracturing many wells in Lake Maracaibo, that the factors which affect the conductivity of the fractures and which are related to the propping agent, are as follows: (1) the load which will be imposed;

J. U. Colina; R. Leibach

1969-01-01

391

PROFILI DI SOSTENIBILITÀ DELL'ADEGUAMENTO SISMICO DEGLI EDIFICI IN C.A  

Microsoft Academic Search

SOMMARIO Il comportamento dinamico di edifici in c.a. progettati per i soli carichi verticali è stato analizzato, al fine di valutarne la vulnerabilità sismica nonché l'efficacia di alcune tecniche di miglioramento, mediante analisi non lineari sia statiche che dinamiche su modelli di telai piani a plasticità concentrata, considerando diversi possibili comportamenti delle cerniere plastiche e utilizzando differenti gruppi di terremoti

Bruno Calderoni; Emilia Angela Cordasco; Pietro Lenza

392

7 CFR 319.37-2 - Prohibited articles.  

Code of Federal Regulations, 2010 CFR

...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela,...

2009-01-01

393

7 CFR 319.37-2 - Prohibited articles.  

Code of Federal Regulations, 2013 CFR

...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela,...

2013-01-01

394

7 CFR 319.37-7 - Postentry quarantine.  

Code of Federal Regulations, 2013 CFR

...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela,...

2013-01-01

395

7 CFR 319.37-2 - Prohibited articles.  

Code of Federal Regulations, 2010 CFR

...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela,...

2010-01-01

396

7 CFR 319.37-7 - Postentry quarantine.  

Code of Federal Regulations, 2010 CFR

...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela, Yugoslavia...Switzerland, Taiwan, Thailand, Tunisia, Ukraine, Uruguay, Venezuela,...

2009-01-01

397

RESISTENCIA ANTIMICROBIANA EN BACTERIAS AISLADAS DE TILAPIAS, AGUA Y SEDIMENTO EN VENEZUELA Antimicrobial Resistance in Bacteria Isolated From Tilapia, Water and Sediment Samples In Venezuela  

Microsoft Academic Search

The indiscriminate use of antimicrobials exerts high selective pressure on bacteria, provoking the emergence and dissemination of genes resistance to them. Considering that in Lake Valencia great volumes of water drain as a consequence of intense anthropogenic activities, the bacterial resistance in feral and cultured tilapia was evaluated, and the inhibitory concentration of selected antimicrobials was determined. The sensitivity was

Julia D. Álvarez; Claudia P. Agurto; Ana M. Álvarez; José Obregón

2004-01-01

398

MORFOANATOMÍA DE LAS GLÁNDULAS EN CUATRO ESPECIES DE PASSIFLORA L. (PASSIFLORACEAE) DE VENEZUELA Morphoanatomy of the glands in four species of Passiflora L. (Passifloraceae) from Venezuela  

Microsoft Academic Search

The secretory glands morphoanatomy in Passiflora species: P. foetida var. moritziana, P. oerstedii, P. suberosa y P. tuberosa was studied, in order to investigate the possible diagnostic value of them in the systematic of that genus. The foliar samples were processed using classical techniques used for preparation of both, optical and scanning electron microscopy. The results show prominent differences among

DAMELIS JÁUREGUI; MARINA GARCÍA; DELIS PÉREZ

399

Apatite Fission-Track Thermochronology, Northern Range, Trinidad (and Paria Peninsula, Venezuela) Apatite Fission-Track Thermochronology, Northern Range, Trinidad (and Paria Peninsula, Venezuela) Abstract  

Microsoft Academic Search

The Northern Range of Trinidad is an east-west trending mountainous exposure of metamorphic rocks located in the Caribbean-South American plate boundary zone. With a maximum elevation of ~1km, the Northern Range is the only place in Trinidad were metamorphic rocks have been exhumed to the surface. Prior to ca. 10 Ma the Caribbean plate was obliquely converging relative to the

Chris W Denison

2008-01-01

400

Prevalencia de deficiencia subclínica de vitamina A y desnutrición en niños marginales de Maracaibo - Venezuela  

Microsoft Academic Search

RESUMEN. El presente estudio fue realizado para estimar la prevalencia de deficiencia de vitamina A en niños, mediante examen clínico, oftalmológico y por citología de impresión conjuntival (CIC); y el estado nutricional, analizando los indicadores antropométricos T\\/\\/E, P\\/\\/E y P\\/\\/T. La población de estudio incluyó 157 niños, 2-6 años de edad, provenientes de barrios marginales urbanos y rurales de Maracaibo,

Haydée V. Castejón; Pablo Ortega; María E. Díaz; Daisy Amaya; Gisela Gómez; María Ramos; María V. Alvarado; Jesús R. Urrieta

401

78 FR 49471 - Ferrosilicon From the Russian Federation and Venezuela: Initiation of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013

...injuring, or threatening material injury to, an industry...ferrosilicon, regardless of grade, including ferrosilicon...product described as slag, if the product meets...and `foundry grade' material. References to `regular grade 75 percent...

2013-08-14

402

78 FR 60846 - Silicomanganese From India, Kazakhstan, and Venezuela: Continuation of Antidumping Duty Orders  

Federal Register 2010, 2011, 2012, 2013

...recurrence of dumping and material injury to an industry...continuation or recurrence of material injury to an industry...briquettes, fines and slag. Silicomanganese is...special carbon steel grades, such as motor lamination...recurrence of dumping and material injury to an...

2013-10-02

403

Tectono-stratigraphic evolution of the Eastern Maturin Foreland basin (Eastern Venezuela)  

SciTech Connect

The Eastern Venezuelan Basin is a classical foreland basin related to the loading of the Serrania del Interior thrust-sheets. The flexure of the basin started during Upper Oligocene-Lower Miocene time and is evidenced by a major unconformity between the Cretaceous and the Lower Miocene Oficina Formation (Basal Foredeep Unconformity). The sedimentary-filling of the Basin commences with coastal transgressive sandstones of the Oficina Formation (Lower Miocene) that constitute the main reservoir of this petroleum province. The overlying deposits of the basin can be subdivided into: (1) Deep-water stage represented by the upper Oficina shales and the Freites Formation in the south and the Carapita Formation in the north (Middle Miocene). This shale interval constitutes the main seal of the region. This stage is characterized by major onlap and a major flooding surface. (2) Progradational stage characterized by shelf-slope deposits of the Lower-Middle La Pica Formation (Upper Miocene). Siliciclastic shelf wedges consisting of deltaic facies. (3) Aggradational stage fluvial-alluvial delta plain deposits represented by the Upper La Pica, Mesa and Las Piedras Formations (Pliocene-Pleistocene). In the northern part of the basin, southward-vergent thrusting deformed the basement and its thin Cretaceous-Lower Miocene cover. South of the Rio Tigre area compressional structures are combined with normal faults related to flexural extension. The boundary between basement-involved thrusting and flexural extension controls the type of structural traps within the basin.

Azavache, A.; Flinch, J.; Giffuni, G.; Martinez, R. [Eastern Maturin Team, Caracas (Venezuela)] [and others

1996-08-01

404

[Dana swimming crab growth Callinectes danae (Decapoda: Portunidae) from Margarita Island, Venezuela].  

PubMed

Callinectes danae is a common species captured with crab traps in nearby areas of coastal lagoons in Margarita Island. Although its considerable economic importance as a fishery resource, few studies have been done on population dynamics and its fishery potential in local coastal environments to support decision making in fishery administration. We present growth pattern details of Callinectes danae to better estimate its population size and exploitation feasibility. For this, we analyzed a total of 3 623 specimens that were monthly captured in crab pots by artisanal fishermen in Las Marites lagoon, from October 2007 to September 2008. The length-weight ratio was determined, and growth parameters estimated from both length and weight curves of the von Bertalanffy model. The general sex ratio showed no significant difference between males and females (chi2 = 0.04, p > 0.05). However, values of slopes b between males and females were significantly different (t(s) = 2.75, p < 0.05), as well as intercepts a (t(s) = 2.44, p < 0.05). Thus, the length-weight ratio was determined separately: W = 7.48e(-5)*L(2.98) for males and W = 1.21e(-4)*L(2.87) for females, indicating a negative allometric growth in both sexes. Growth parameters were established as: L(infinity) =134.80mm, W(infinity) = 166.04g and k = 0.86/yr for males; L(infinity) = 122.35mm, W(infinity) = 118.45g and k = 0.63/yr for females. Lifespan was estimated at 3.05 years for males and 4.24 years for females. We concluded that Callinectes danae is a species with short lifespan and moderately rapid growth. The coefficient of variation values (CV), of the phi-prime growth performance index (Ø'), showed a different growth pattern compared to those obtained in other regions. We propose that a management strategy will be the periodical review of the minimum capture size for fishing area, after the great variability found in growth parameters. PMID:22208071

Castillo, Jesylén; Eslava, Nora; González, Leo Walter

2011-12-01

405

The differential impact of real interest rates and credit availability on private investment: evidence from Venezuela  

Microsoft Academic Search

In the 1970's, some economists, led by McKinnon (1973) and Shaw (1973), began to argue in favor of financial liberalization as a medium of promoting saving, investment, and growth. This was based on the argument that real interest rates are frequently negative in developing countries due to administrative controls on the nominal interest rates and heavy regulation in the financial

Omar A Mendoza Lugo

406

Scratching Behind the Walls; Graffiti and Symbolic Political Imagination at Cuartel San Carlos (Caracas, Venezuela)  

Microsoft Academic Search

\\u000a Rock art is as old as human history. South American rock carvings and paintings provide invaluable evidence of our aboriginal\\u000a past. As a matter of fact, spontaneous artistic interventions on buildings and walls (equivalent to modern graffiti) appear\\u000a for the first time in Ancient Egypt and Greece. But urban graffiti is definitely a modern phenomenon. It is typical of late

Rodrigo Navarrete Sánchez; Ana María López

407

Venezuela: Agricultural Situation. Government Plans for Its New Milk Company 2008. GAIN Report Number VE8022.  

National Technical Information Service (NTIS)

According to reports, the recently purchased Lacteos Los Andes will be converted into a socialist production enterprise called ENLANDES, and be required to increase social development programs and change its product lines.

C. Nunez

2008-01-01

408

Lithostratigraphy of the Mérida (Wisconsinan) glaciation and Pedregal interstade, Mérida Andes, northwestern Venezuela  

Microsoft Academic Search

At Pedregal, more than 40 m of sediments are exposed within a `fan complex' formed between lateral moraines of the adjacent Mucuchache and El Caballo valleys. Early and late Mérida (Wisconsinan) glaciations are represented by till and till plus proglacial sediments, respectively. A middle Wisconsinan interstadial event, here termed the Pedregal interstade, began at the end of the Early Mérida

Randy W. Dirszowsky; William C. Mahaney; Kyle R. Hodder; Michael W. Milner; Volli Kalm; Maximiliano Bezada; Roelf P. Beukens

2005-01-01

409

Treading & threading memories: a personal encounter with forest and people in Southern Venezuela.  

PubMed

This brief essay, which represents the third editorial of the series "Recollections, Reflections, and Revelations: Ethnobiologists and their First Time in the Field", captures a few memories of the author's first fieldwork in the Venezuelan rainforest. It is a collage of objects, subjects, feelings, spaces, and events that pendulate in spheres of meaning straddling between the author's identities as both a student and a woman. The author's evocations of fifteen years ago are diluted in lasting reflections about what could be ethnoecology embraced by spaces of interactions and associations between organisms and their surroundings. PMID:23915266

Zent, Egleé L

2013-08-06

410

Analysis of the Early Performance of the M-6 Steam-Drive Project, Venezuela  

Microsoft Academic Search

Since January 1978 Maraven has been conducting the M-6 Steam Drive Project in Tia Juana, one of the Bolivar Coast Heavy Oil Reservoirs near Lake Maracaibo. The project is carried out on a semi-open seven-spot well configuration, using the existing 231-m grid and comprises at present 21 injectors and 130 producers. The project area is 7.4 km², depth 1800 ft

L. Schenk

1982-01-01

411

Palabras clave: ÉTICA Y DOCENCIA\\/ LIDERAZGO EDUCATIVO\\/ EDUCACIÓN EN VALORES\\/ APRENDIZAJE Y CONVIVENCIA\\/ PROFESOR UNIVERSITARIO\\/ VENEZUELA  

Microsoft Academic Search

The purpose of this article is to share some reflections around the paper that the educational university professor should assume in role of educational leaders, under an ethical perspective of the teaching based on the formation of securities, as fundamental pillars for the life in coexistence. Starting from a bibliographical revision, it was obtained as a result that the educational

Ana Teresa Prieto Sánchez

412

Evaluation of the OptiMAL test for diagnosis of malaria in Venezuela.  

PubMed

We evaluated the OptiMAL rapid dipstick test by comparing it with the conventional standard thick-blood film method, for the detection of malaria in two groups of individuals from different Venezuelan endemic areas. One of the groups consisted of individuals with malaria-like symptoms (n = 113) and the other of asymptomatic individuals (n = 89). The classical microscopy analysis of these populations determined that 67.5% were infected with P. vivax, 31.3% with P. falciparum, and 1.2% with mixed infections. The OptiMAL test showed 96.4% sensitivity, 100% specificity, 100% positive predictive value, 97.5% negative predictive value and optimal concordance (kappa = 0.97), capable of detecting any malaria infection in the evaluated population. However, these parameters were lower when the parasitaemia was < or = 300 parasites/microL. Freezing of the samples did not affect the sensitivity and specificity of the test. We concluded that this rapid malaria test is sensitive and specific for rapid diagnosis of malaria in the field and it is a complement to conventional microscopy. PMID:18524335

Zerpa, Noraida; Pabón, Rosalba; Wide, Albina; Gavidia, Magda; Medina, Mehudi; Cáceres, José Luis; Capaldo, Jacinta; Baker, Meghan; Noya, Oscar

2008-03-01

413

Biological monitoring of mercury exposure in individuals referred to a toxicological center in Venezuela  

Microsoft Academic Search

People in developing countries are often considered at greater risk of mercury (Hg) poisoning due to a variety of factors including a lack of awareness regarding their occupational risks. Individuals requiring urine mercury (U-Hg) analysis at the Center for Toxicological Investigations of the University of Carabobo (CITUC), between 1998 and 2002 were studied to identify demographic characteristics associated to U-Hg

Maritza Rojas; David Seijas; Olga Agreda; Maritza Rodríguez

2006-01-01

414

Epidemiological and immunological aspects of human visceral leishmaniasis on Margarita Island, Venezuela.  

PubMed

Sixty-five patients were diagnosed with visceral leishmaniasis (VL) on Margarita Island in the decade from 1990 to1999; 86.2% were <= 3 years old. All were leishmanin-negative at diagnosis. Evaluation of 23 cured patients in 1999 revealed that 22/23 had converted to leishmanin-positive; five had persisting antibodies to rK39 antigen, with no clinical evidence of disease. Leishmanin tests were positive in 20.2% of 1,643 healthy individuals from 417 households in endemic areas. Of the positive reactors, 39.8% were identified in 35 (8.4%) of the households, 15 of which had an antecedent case of VL, a serologically positive dog or both. Weak serological activity to rK39 antigen was detected in 3 of 488 human sera from the endemic areas. The presence of micro-foci of intense peri-urban transmission and the apparent absence of other Trypanosomatidae causing human disease offer a unique opportunity for the study of reservoirs, alternative vectors and evaluation of control measures on the Island. PMID:12563469

Zerpa, Olga; Ulrich, Marian; Benitez, Margarita; Avila, Concepción; Rodríguez, Vestalia; Centeno, Marta; Belizario, Doris; Reed, Steven G; Convit, Jacinto

2003-01-20

415

Seismic inversion of the Tertiary reservoir in the Southeastern part of Lake Maracaibo, Venezuela  

SciTech Connect

Seismic inversion has been tested previously in the Lake Maracaibo area by the Maraven Exploration and is now being applied by the production group. Area 8, in the southeastern part of the Ceuta Field, was selected for the inversion study to improve the parameters for the planned waterflood project. The reservoir is located in a monoclinal fault block bounded by north dipping east-west normal faults and the Ceuta High Structure to the west. The producing zones, Eocene Misoa Formation Sands B and C, appear to have stratigraphic limits which this study was undertaken to define and characterize. The methodology consists of two parts; acoustic petrophysics and seismic inversion. The results are integrated in order to produce the final qualitative and quantitative reservoir model. In the acoustic petrophysics section, the impedance computed from the well logs is compared with known petrophysical properties. The derived relationships are used for petrophysical predictions and their quantitizication by transfer functions. In the seismic inversion section, seismic data were inverted via a forward modeling technique with constraining parameters derived from wells. The resulting seismic acoustic impedance was tested and calibrated to well data. The impedance displays, generated for a grid of seismic lines, were interpreted for stratigraphic definition and, in the reservoir zone, converted to selected petrophysical parameters. These parameters were mapped, resulting in reservoir models that can be used for the waterflood planning.

Kudrna, A.J. (Maraven S.A., Caracas (Venezuela))

1993-02-01

416

Foreign Economic Trends and Their Implications for the United States: Venezuela.  

National Technical Information Service (NTIS)

The series of reports presents current business and economic developments in every country that offers a present or potential market for United States goods. The reports include a summary of the prospective impact on the United States economy, changing tr...

S. Stack

1971-01-01

417

Columnar cacti-shrub relationships in an Andean semiarid valley in western Venezuela  

Microsoft Academic Search

Spatial associations between columnar cacti and mimosoid shrubs were evaluated in an Andean semidesert enclave. An analysis\\u000a on the capacity of other deciduous shrub species and medium-sized ephemeral plants to modify the spatial distribution of cacti\\u000a was also included. The number of Stenocereus griseus (Haw.) F. Buxb., Cereus repandus (L.) Backeb. and Pilosocereus tillianus Gruber & Schaftzl that grow below

Daniel M. Larrea-Alcázar; Pascual J. Soriano

2008-01-01

418

Effects of agroindustrial SEM production in Mérida, Venezuela: A response with environmental indicators  

Microsoft Academic Search

Any incentive program directed to the productive sector should include a very important factor represented by all actors that drive the national economy: small and medium agricultural and industrial enterprise. One weakness of this important segment is related to the lack of criteria for environmental management, given their particular activity. Based on this premise, the central objective of this research

Aura Elena Peña; Hiner Eveli González

2008-01-01

419

Early sexual maturity among Pumé foragers of Venezuela: fitness implications of teen motherhood.  

PubMed

Because humans have slow life histories, discussions of the optimal age at first birth have stressed the benefits of delayed reproduction. However, given the diversity of ecological, fertility, and mortality environments in which humans live, reproductive maturity is expected to be highly variable. This article uses reproductive histories to examine a pattern of early menarche and first birth among the Pume, a group of South American foragers. Age at menarche and first birth are constructed using both retrospective and cross-sectional data for females over the age of 10 (n = 83). The objectives are first to define these patterns and then discuss their reproductive consequences. On average, Pume girls reach menarche at age 12.9, and give birth to their first child at age 15.3-15.5 (retrospective and cross-sectional data, respectively). This populational average falls several years prior to what often is considered the human norm. Two questions are then considered. What are the infant mortality costs across a mother's reproductive career? How does surviving fertility vary with age at first birth? Results indicate that the youngest of first-time mothers (<14) are four times more likely to loose their firstborns than older first-time mothers (> or =17). Given parity-specific mortality rates, the optimal strategy to minimize infant mortality and maximize reproductive span is to initiate childbearing in the midteens. Women gain no additional advantage in surviving fertility by delaying childbearing until their late teens. PMID:18386795

Kramer, Karen L

2008-07-01

420

Microtremors Measurements In Cumana City (venezuela). Firsts Results For A Microzoning Analysis.  

NASA Astrophysics Data System (ADS)

Changing solar activity is a possible factor behind rapid climate shifts. Matching of high resolution sequences of uncalibrated 14C dates of organic deposits to the dendro- calibration curve can provide a precise core chronology. This method (14C wiggle matching) reveals relationships between atmospheric 14C variations and short-term climatic fluctuations caused by solar variations. Shifts to cool and wet climate types in the temperate zones correspond to phases of increasing and high values of delta 14C, pointing to a link between changing solar activity and climate change. In the temperate zones the transition from the Subboreal to the Subatlantic (ca 850 calendar years BC) represents a sudden and strong shift from a relatively dry and warm climate to a humid and cool episode. The climate shift is reflected in the plant macrofossil composition of NW European raised bogs, but there is also strong archaeological and dendroclimatological evidence. The climate shift occurs at the start of a sharp rise of the atmospheric 14C content, caused by a sudden decline of solar activity. Reduced solar wind permitted more cosmic rays to penetrate into the atmosphere, resulting in a higher production of the cosmogenic isotope 14C. In Cameroon and other sites in the Central African rain forest belt there was a drastic change in the vegetation cover as a consequence dryness after ca 850 cal BC. Shortly afterwards farmers migrated into the area, availing themselves of what was from the human standpoint a regional climatic improvement. A possible palaeoclimatological explanation for the dry-wet transition in the temperate zones, and the contemporaneous wet-dry transition in the tropics is the following: A reduction in solar activity (less solar UV) resulted in a decrease of stratospheric ozone, less absorption of warmth, an equatorward shift and intensification of the mid-latitude storm tracks, a constriction of the latitudinal extent of the Hadley Cell circulation and thus a weaker monsoon. The recorded paleoclima- tological teleconnections point to a considerable role of solar UV in climate forcing and may indicate that changing solar wind and related changes of cosmic ray intensity (possibly causing fluctuations of cloud formation) were less important. Ref.: van Geel, B. et al., in press. Evidence from the past: solar forcing of climate change by way of cosmic rays and/or by solar UV? Proceedings of the Workshop on Ion-Aerosol-Cloud Interactions, Geneva, ed. J. Kirkby, CERN 2001-007

Posadas, A.; Martin, J.; Avendaño, J.; Sierra, R.; Bonive, F.

421

ANATOMÍA FOLIAR DE PASSIFLORA GUAZUMAEFOLIA JUSS. Y PASSIFLORA AFF. TILIAEFOLIA L. (PASSIFLORACEAE) PRESENTES EN VENEZUELA  

Microsoft Academic Search

Leaf anatomy of Passiflora guazumaefolia and Passiflora aff. tiliaefolia was studied in order to find out the possible existence of histological features of taxonomic value. Fresh leaves were fixed in FAA and samples were processed using classical techniques to obtain both, free hand sections of blade and petiole and as well as leaf macerations. Micromorphology of the leaves using scanning

M. García; D. Jáuregui; D. Pérez

422

Human infection by Fasciola hepatica in Venezuela: report of a geriatric case.  

PubMed

A new case of human infection due to Fasciola hepatica is reported in the Venezuelan parasitological literature. The patient is an 81-year-old female asymptomatic, with an eosinophilia of 21% and critrosedimentation rate of 26 mm/h and was found during a routine check up. These values were normal at the time of treatment (4 months later), as were several tests of hepatic function, blood chemistry and peripheral blood haematological values. The number of eggs of the parasite were between 90 and 130/g of facees. The patient was successfully treated with the human formulation of trielabendazole at 2 single doses of 10 mg/kg, each separated by 24 h. The same laboratory tests mentioned above did not show modifications, except for a slight increase in the cosinophil counts at 2 and 11 days and erythrosedimentation rate at 11 days post-treatment. Coproparasitological observations carried out at 12, 18, 60 and 120 days post-treatment were negative. No clinical symptoms were registered up to 2 months after treatment. The patient most probably acquired the infection at home through the ingestion of commercially available lettuce from an endemic area of bovine fascioliasis, very distant from home, and between 4 and 7 months previous to treatment. We stress the need to investigate F. hepatica infections which he been neglected, probably because of limited knowledge by health workers, lack of specific symptoms and absence of more sensitive diagnostic procedures. PMID:14552063

Incani, Renzo Nino; Vieira, Juan Manuel; Pacheco, Mercedes; Planchart, Sandra; Amarista, Manuel; Lazdins, Janis

2003-09-01

423

Ehrlichia canis-like agent isolated from a man in Venezuela: antigenic and genetic characterization.  

PubMed

We report the first isolation and molecular and antigenic characterization of a human ehrlichial species in South America. A retrospective study was performed with serum specimens from 6 children with clinical signs suggestive of human ehrlichiosis and 43 apparently healthy adults who had a close contact with dogs exhibiting clinical signs compatible with canine ehrlichiosis. The evaluation was performed by the indirect fluorescent-antibody assay with Ehrlichia chaffeensis Arkansas, Ehrlichia canis Oklahoma, and Ehrlichia muris antigens. The sera from two apparently healthy humans were positive by the indirect fluorescent-antibody assay for all three antigens. Of the three antigens, samples from humans 1 and 2 showed the highest antibody titers against E. chaffeensis and E. muris, respectively. The remaining serum samples were negative for all three antigens. One year later examination of a blood sample from subject 1 revealed morulae morphologically resembling either E. canis, E. chaffeensis, or E. muris in monocytes in the blood smear. The microorganism, referred to here as Venezuelan human ehrlichia (VHE), was isolated from the blood of this person at 4 days after coculturing isolated blood leukocytes with a dog macrophage cell line (DH82). The organism was also isolated from mice 10 days after intraperitoneal inoculation of blood leukocytes from subject 1. Analysis by electron microscopy showed that the human isolate was ultrastructurally similar to E. canis, E. chaffeensis, and E. muris. When the virulence of VHE in mice was compared with those of E. chaffeensis, E. canis, and E. muris, only VHE and E. muris induced clinical signs in BALB/c mice at 4 and 10 days, respectively, after intraperitoneal inoculation. VHE was reisolated from peritoneal exudate cells of the mice. Only E. chaffeensis- and E. muris-infected mice developed significant splenomegaly. Western immunoblot analysis showed that serum from subject 1 reacted with major proteins of the VHE antigen of 110, 80, 76, 58, 43, 35, and 34 kDa. Human serum against E. chaffeensis reacted strongly with 58-, 54-, 52-, and 40-kDa proteins of the VHE antigen. Anti-E. canis dog serum reacted strongly with 26- and 24-kDa proteins of VHE. In contrast, anti-E. sennetsu rabbit and anti-E. muris mouse sera did not react with the VHE antigen. Serum from subject 1 reacted with major proteins of 90, 64, or 47 kDa of the E. chaffeensis, E. canis, and E. muris antigens. This reaction pattern suggests that this serum sample was similar to serum samples from E. chaffeensis-infected human patients in Oklahoma. The base sequence of the 16S rRNA gene of VHE was most closely related to that of E. canis Oklahoma. On the basis of these observations, we suggest that VHE is a new strain or a subspecies of E. canis which may cause asymptomatic persistent infection in humans. PMID:8862572

Perez, M; Rikihisa, Y; Wen, B

1996-09-01

424

The Market for Scientific Crime Prevention: A Comparative Study of Canada and Venezuela  

Microsoft Academic Search

Crime prevention is an activity that, sooner or later, requires the concourse of science. But the dictates of science may\\u000a not mesh well with the social, institutional and political considerations that are persistent and powerful determinants of\\u000a collective action. To the extent that they are ignored, crime prevention is less scientific and more pragmatic. Using a marketing\\u000a metaphor, this paper

Christopher Birkbeck

2005-01-01

425

A palynological record of a secondary succession after fire in the Gran Sabana, Venezuela  

Microsoft Academic Search

Fire has been considered one of the most important factors in the expansion of savannas in the Gran Sabana region. In Urué, an important fire event that occurred before 1.6 kyr BP led to the replacement of primary forests by savannas and morichales (monospecific communities of the palm Mauritia). In the present work, the secondary succession after fire is reconstructed

Valentí Rull

1999-01-01

426

Hydrocarbon generation potential of the Cretaceous section from Well ALP-6, Perija Region, Venezuela  

SciTech Connect

Geochemistry and sedimentology have been integrated in order to provide a better understanding of the source rock potential and depositional environments of the La Luna Formation and Machiques Member in Well ALP-6 (Perija region). These two units, the dominant source rocks in the Maracaibo Basin, are mainly shales with high to very high organic content, while thin interbeds of limestones are poor in organic matter. A detailed sedimentological study and sequence analysis indicates that both shaly units represent a period of platform infilling subsequent to drowning. Periods of progressive back stepping culminating in the deposition of organic-rich condensed intervals are recognized, based on sedimentology of cores and wireline log analysis. A succession of fining-upward sequences, 1' to 5' thick, with distinct sedimentological and geochemical signatures have been identified in the La Luna Formation. Phenomena of early diagenesis (intrashale calcite growth due to organic matter degradation; sulfur precipitated in local paleolows) to late diagenesis (pressure-solution effects with development of laterally correlatable cone-in-cone layers) are all indicators that the hydrocarbon generation potential of La Luna is not uniform and can only be assessed by detailed geological, sedimentological and geochemical investigations. Two geochemically distinct facies can be identified in both La Luna and Machiques. A sulfur-rich facies is characterized by Corg/AVSul ratios averaging 1.9 and by exceptionally high concentrations of sulfur-bearing aromatic compounds. A sulfur-poor facies is characterized by Corg/AVSul ratios averaging 9.2 and by trace concentrations or absence of sulfur-bearing aromatic compounds.

Pratt, L. (Indiana Univ., Bloomington, IN (United States)); Mompart, L.; Murat, B. (Maraven S.A., Caracas (Venezuela))

1993-02-01

427

Study of the antibody response against Mycobacterium tuberculosis antigens in Warao Amerindian children in Venezuela  

Microsoft Academic Search

This study was aimed at investigating alternate methods for serodiagnosis of tuberculosis (TB), which are needed because bacteriologic diagnosis of childhood TB is difficult. A selection of 80 serum and saliva samples were tested from Warao indigenous children under 15 years of age; 34 high TB suspects (28 positive and 6 negative for the tuberculin skin test, TST) and 46

Z Araujo; JH de Waard; C Fernández de Larrea; D López; C Fandiño; A Maldonado; E Hernández; Y Ocaña; R Ortega; M Singh; Tom HM Ottenhoff; SM Arend; J Convit

2004-01-01

428

[Scytalidium dimidiatum an opportunistic fungus for both man and Mangifera indica trees in Venezuela].  

PubMed

The purpose of this study was to confirm the presence of Scytalidium dimidiatum on Mangifera indica (mango) trees, in a plantation managed by a diabetic patient with a white grain mycetoma of the foot caused by the same fungus. Samples from necrotic apices, roots, burned leaves and rotten stems from eight trees were processed by the Smith and Furcolow's mineral oil technique (modified). Several isolates from the apex material and clinical samples from the diabetic patient isolated in pure culture a fungus with the macroscopic and microscopic characteristics of that in S. dimidiatum. This fungus should be considered as an opportunistic microorganism for both humans and M. indica. PMID:16309356

Padin, Carmiña; Fernández-Zeppenfeldt, Guillermo; Yegres, Francisco; Richard-Yegres, Nicole

2005-09-01

429

Brassica napus L. Ficha botánica de interés apícola en Venezuela, No. 8 Nabo  

Microsoft Academic Search

Brassica napus L. is a foraging herb with oily seeds visited by numerous bee species in search of nectar and pollen. This work is included in a series to study the importance of Venezuelan bee flora. The pollen is yellow, suboblate, approximately 20 ?m diameter, tricolpate, and reticulate exine. The botanical description and bee observations of rapeseed are included in

PATRICIA VIT; MATERIALES Y MÉTODOS

2004-01-01

430

ALCOHOL USE AND CULTURAL CHANGE IN AN INDIGENOUS POPULATION: A CASE STUDY FROM VENEZUELA  

Microsoft Academic Search

Aims: To explore the historical and cultural context of problem drinking in a Latin American indigenous population and identify possible areas for intervention. Methods: Focus group discussions. Results: Participants reported that prior to 1945, binge drinking and fighting were part of cultural festivals held several times each year. Alcohol was brewed in limited quantities by specially qualified individuals. Limited family

J. PAUL SEALE; SYLVIA SHELLENBERGER; CARLOS RODRIGUEZ; JOSIAH D. SEALE; MANUEL ALVARADO

2002-01-01

431

Chemical composition of the essential oil of Croton gossypiifolius from Venezuela.  

PubMed

The essential oil from leaves of Croton gossypiifolius Vahl. (Euphorbiaceae) was obtained by hydrodistillation, and analyzed by GC/FID and GC/MS. The constituents were identified by their mass spectra and Kovats' indices. Fifty-one compounds accounting for 92% of the oil were detected, and 47 of them were identified. The oil was dominated by oxygenated sesquiterpenes with the major presence of alpha-cedrene oxide (18.6%), spathulenol (16.3%), valencene (5.8%), geranyl-pentanoate (5.3%), alpha-cadinol (4.0%), germacrene D (3.5%) and longifolene (3.3%). PMID:21366055

Suárez, Alírica I; Oropeza, Marly; Vásquez, Luis; Tillett, Stephen; Compagnone, Reinaldo S

2011-01-01

432

Within-plate deformations in the Maracaibo and East Zulia basins, western Venezuela  

Microsoft Academic Search

Subsurface data help in understanding the complex geometry of major structures of the Maracaibo basin and surrounding areas. During extensional and compressional phases, decoupling levels were activated in the Upper Cretaceous black shales and the Paleogene flysch sequences, thus inducing frequent disharmony between a rigid basement and thin-skinned cover structures.Two main extensional episodes are widespread across the Maracaibo basin: the

François Roure; Bernard Colletta; Bruno De Toni; Daniel Loureiro; Herminio Passalacqua; Yves Gou

1997-01-01

433

Sequential evolution of Lower Cretaceous carbonate platforms in the Maracaibo Basin, Venezuela  

SciTech Connect

The sequence stratigraphic framework of the Upper Barremian to the Upper Cenomanian series was carried out in detail on cored material and well logs from Perija region and central part of Lake Maracaibo. Sediments are predominantly shallow marine carbonates (muddy lagoons, grainstone bars, pelecypod biostroms, intrabars), with an occasional siliciclastic input (nearshore sand bars, mixed tidal flats). Three second order cycles representing various stages of the evolution of the Cogollo platform have been identified. Cycle I (Upper Barremian-Lower Aptian) is a time transgressive unit, bounded at the base by backstepping sandstones (Rio Negro Formation) and at the top by a drowning unconformity (Machiques Member). Cycle II (Upper Aptian-Middle Albian) is a complete second-order cycle with a regressive phase followed by a long-term transgression. It corresponds mainly to the Apon Formation, and it is limited by two drowning unconformities: the Machiques at the base and the basal Lisure at the top. It is made up of 7 depositional sequences. They are slightly prograding during the regressive phase, aggrading and then backstepping during the transgression. Cycle III (Upper Albian-Upper Cenomanian) is another complete second-order cycle covering the Lisure, Maraca and La Luna Formations. The drowning unconformity at the top of the Maraca Formation is not the peak transgression, this one is at the top of La Luna Formation at the Cenomanian/Turonian boundary. Cycle III is made up of 15 depositional sequences. This sequence stratigraphic framework reveals that carbonate reservoirs of the Cogollo group are best developed at the top of highstand systems tracts.

Jacquin, T. (URA CNRS, Paris (France)); Azpiritxaga, I.; Murat, B.; Roberto, M.F. (Maraven, Caracas (Venezuela))

1993-02-01

434

Arms Transfers to Venezuela: A Critical Analysis of the Acquisition Process, 1962-1975.  

National Technical Information Service (NTIS)

Extensive research has been made regarding military expenditures and arms transfers in and to Latin America. Nevertheless, there was no available study focusing research on arms transfers from the perspective of a particular Latin American nation. The aut...

M. Suarez

1977-01-01

435

Chemical composition and biological activity of Conyza bonariensis essential oil collected in Mérida, Venezuela.  

PubMed

The essential oil from aerial parts of Conyza bonariensis (L) Cronquist collected in Mérida was obtained by hydrodistillation and analysed by GC/MS. The major components were trans-beta-farnesene (37.8%), trans-ocimene (20.7%) and beta-sesquiphellandrene (9.8%). Cytotoxicity assay was also performed with the essential oil against HeLa (cervix carcinoma), A-459 (lung carcinoma) and MCF-7 (breast adenocarcinoma) human cell lines and against normal Vero cells (African green monkey kidney) with IC50 values ranging from 1.4 to 45.8 microg/mL. Additionally, the essential oil presented a significant bactericidal effect against Bacillus cereus, while a moderate activity was observed against Staphylococcus epidermidis and Candida albicans. PMID:24079198

Araujo, Liliana; Moujir, Laila M; Rojas, Janne; Rojas, Luis; Carmona, Juan; Rondón, María

2013-08-01

436

Distribution of metals in mechanical fractions of soils from a lake catchment in Venezuela  

Microsoft Academic Search

Soil samples were collected from both the surface and at depth from the lowlands around Lake Valencia and from the adjacent mountains. This paper reports results for Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn in mechanical fractions of the soils. Lowland soils, developed on lacustrine sediments, show a predominance of medium- to fine-grain

Claudio Bifano; Brian E. Davies

1995-01-01

437

Flexural and gravity modelling of the Mérida Andes and Barinas Apure Basin, Western Venezuela  

NASA Astrophysics Data System (ADS)

The kinematic evolution of the Barinas Apure Basin and the southern Mérida Andes from Lower Miocene to the Present is numerically modelled using flexural isostatic theory and geophysical and geological data. Two published regional transects are used to build up a reference section, which is then used to constrain important parameters (e.g. shortenings and sedimentary thicknesses) for the flexural modelling. To control the location of the main fault system in the flexural model earthquake information is also used. The estimated flexural elastic thickness of the South American lithosphere beneath the Barinas Apure Basin and the Mérida Andes Range is 25 km. The value for the final total shortening is 60 km. The flexural isostatic model shows that the Andean uplift has caused the South American lithosphere subsidence and the development of the Barinas Apure Basin. In addition, gravity modelling was used to understand deep crustal features that could not be predicted by flexural theory. Consequently, the best-fit flexural model is used to build a gravity model across the Mérida Andes and the Barinas Apure Basin preserving the best-controlled structural features from the flexural modelling (e.g. basin wavelength and depth) and slightly changing the main bodies density values and deep crustal structures. The final gravity model is intended to be representative of the major features affecting the gravity field in the study area. The predicted morphology in the lower crustal level of the final gravity model favours the hypothesis of a present delamination or megathrust of the Maracaibo crust over the South American Shield. This process would use the Conrad discontinuity as a main detachment surface within an incipient NW dipping continental subduction.

Chacín, Luis; Jácome, María I.; Izarra, Carlos

2005-08-01

438

Major element chemistry, weathering and element yields for the Caura River drainage, Venezuela  

Microsoft Academic Search

The Caura River, a major tributary of the Orinoco River, was sampled at bi-weekly intervals for two years. Because the watershed is covered with undisturbed forest overlying a Precambrian shield, the water of the Caura River has low conductivity (mean, 15 uS\\/cm), contains small amounts of particulate material (mean, 11 mg\\/1), and is slightly acidic (median pH, 6.8). Concentrations of

William M. Lewis; Stephen K. Hamilton; Sandra L. Jones; Donald D. Runnels

1987-01-01

439

Analysis of the early performance of the M-6 steam-drive project, Venezuela  

SciTech Connect

Since January 1978 Maraven is conducting the M-6 Steam Drive Project in Tia Juana, one of the Bolivar Coast Heavy Oil Reservoirs near Lake Maracaibo. The project is carried out on a semi-open seven-spot well configuration, using the existing 231-m grid and comprises at present 21 injectors and 130 producers. The project area is 7,4 Km/sup 2/, depth 1800 ft ss, and originally contained 525 million bbl of 13 degr. API Crude. The recovery by primary depletion, enhanced by steam soak, was 22 pct. STOIIP at the start of steam drive. 4 refs.

Schenk, L.

1982-01-01

440

Analysis of the early performance of the M-6 steam-drive project, Venezuela  

SciTech Connect

Since January 1978 Maraven has been conducting the M-6 Steam Drive Project in Tia Juana, one of the Bolivar Coast Heavy Oil Reservoirs near Lake Maracaibo. The project is carried out on a semi-open seven-spot well configuration, using the existing 231-m grid and comprises at present 21 injectors and 130 producers. The project area is 7.4 km/sup 2/, depth 1800 ft ss, and originally contained 525 million bbl of 13 degr. API Crude. The recovery by primary depletion, enhanced by steam soak, was 22 % STOIIP at the start of steam drive. Steam is supplied by a plant with a nominal capacity of 10,000 t/d of saturated, dry steam at 1000 psig. Lake Maracaibo water softened by ion-exchange is used as feed water and natural gas as fuel. Following a build-up period of 6 months the steam injection rate has ranged between 6000 and 8500 t/d, averaging 7400 t/d up to the end of 1981, at well head pressures of around 500 psig. The oil production increased from a pre-project level of 8000 b/d to 18,000 to 23,000 b/d since early 1980, accompanied by an increase in water production from 4000 up to 40,000 b/d. Cumulative performance data for the period January 1978 to December 1981 are: steam injected 10.2 million tons, oil produced 23.7 million bbl, extra oil produced 15.9 million bbl and water produced 33.0 million bbl. Corresponding main project parameters are: cumulative oil production 4.5% STOIIP, of which 3% STOIIP is extra, oil/steam ratio 2.3 bbl/ton, extra-oil/steam ratio 1.6 bbl/ton. (JMT)

Schenk, L.

1982-01-01

441

SUELOS DE LA CUENCA DEL SANTO DOMINGO. SECTOR LAS MESAS. (CARACTERIZACIÓN FÍSICO- QUÍMICA). MÉRIDA-VENEZUELA  

Microsoft Academic Search

The soils of the area of Las Mesas, basin Santo Domingo, Mérida state, are conditioned in the fundamental for the position geomorphologic of strong slopes. The action biochemical is the one which permits the construction of the soils in spite of the conditions of discharges precipitation and of moderate temperatures. The soils in accordance with Soil Taxonomy (Soil Survey Staff,

Dolores Gutiérrez; Guido Ochoa; Jajaira Oballos; Juan Carlos Velásquez

442

Stereoselective biodegradation of tricyclic terpanes in heavy oils from the Bolivar Coastal Fields, Venezuela  

Microsoft Academic Search

Gas chromatography–mass spectrometry (GC–MS) and GC–MS–MS analyses of heavy oils from Bolivar Coastal Fields (Lagunillas Field) show a complete set of demethylated tricyclic terpanes. As is the case for the 25-norhopanes, the demethylated tricyclics are probably formed in reservoirs by microbially-mediated removal of the methyl group from the C-10 position, generating putative 17-nor-tricyclic terpanes. Diastereomeric pairs of tricyclic terpanes are

M. Alberdi; J. M. Moldowan; K. E. Peters; J. E. Dahl

2001-01-01