University Centro Occidental Lisandro Alvarado
University Centro Occidental Lisandro Alvarado
Briedis G.S.,University Centro Occidental Lisandro Alvarado
Interciencia | Year: 2013
Aquatic hyphomycetes are important components of water courses from the ecological and biotechnological points of view, due to their enzymatic battery and thus are considered as indicators of water quality. They are a group of microscopic anamorphic fungi that, in the aquatic ecosystem, degrade and alter the plant material that falls into the water, thereby enabling it to be used as a food resource by other organisms. In Venezuela, studies have been made that increase the records of these fungi species in different streams. The aim of this study was to elaborate an inventory of hyphomycetes species in 'La Estación' stream, located at the Ecological Station 'La Guáquira', Yaracuy State, and relate it to local physicochemical and microbio-logical factors. Weekly samples were collected during a year, under sterile conditions, from stream water and foam, in order to analyze the water quality and identify the fungi species. A total of 40 species were identified, of which Dicranidion gracile and Isthmotricladia laeensis are new reports for the country. Significant relationships were only found between the richness/abundance of conidia and the precipitation regime: Campylospora parvula, Clavastospora tentacula and Diplocladiella sp. were present only during the dry season, while Campylospora filicladia and Campylospora chaetocladia were present only during the rainy season.
Garcia-Orellana Y.,University Centro Occidental Lisandro Alvarado |
Ortuno M.F.,CSIC - Center of Edafology and Applied Biology of the Segura |
Conejero W.,CSIC - Center of Edafology and Applied Biology of the Segura |
Ruiz-Sanchez M.C.,CSIC - Center of Edafology and Applied Biology of the Segura |
Ruiz-Sanchez M.C.,Technical University of Cartagena
Spanish Journal of Agricultural Research | Year: 2013
Field-grown lemon trees [Citrus limon (L.) Burm. fil. cv. Fino] were subjected to different drip irrigation treatments: a control treatment, irrigated daily above crop water requirements in order to obtain non-limiting soil water conditions and two deficit irrigation treatments, reducing the water applied according to the maximum daily trunk shrinkage (MDS) signal intensity (actual MDS/control treatment MDS) threshold values of 1.25 (T1 treatment) and 1.35 (T2 treatment), which induced two different drought stress levels. Daily variations in leaf (Ψleaf) and stem (Ψstem) water potentials, leaf conductance, net photosynthesis, sap flow (SF) and trunk diameter fluctuations were studied on four occasions during the lemon fruit growth period. Ψstem and Ψleaf revealed a diurnal pattern in response to changes in evaporative demand of the atmosphere. Both water potentials decreased in response to water deficits, which were more pronounced in the T2 treatment. Ψstem was seen to be a better plant water status indicator than Ψleaf. The difference between the two values of Ψ (Ψstem-Ψleaf = ΔΨ) was closely correlated with sap flow, making it a suitable measure of leaf transpiration. Using the slope of this relationship, the canopy hydraulic conductance (KC) was estimated. When other continuously recorded plant-based indicators are not accessible, the concurrent measurement of leaf and stem water potentials at midday, which are relatively inexpensive to measure and user-friendly, act as sufficiently good indicators of the plant water status in field grown Fino lemon trees.
Tobar I.B.,Andrés Bello University |
Parra F.,Hospital Central Antonio Maria Pineda |
Perez C.N.,Andrés Bello University |
Rodriguez-Bonfante C.,University Centro Occidental Lisandro Alvarado |
And 2 more authors.
Revista da Sociedade Brasileira de Medicina Tropical | Year: 2011
Introduction: Heart failure (HF) represents the final stage of chronic chagasic cardiomyopathy (CChC). The diagnosis of CChC is based on the demonstration of anti-Trypanosoma cruzi antibodies (aTcAg) and clinical and epidemiological data. In Venezuela, there are no data about the prevalence of chagasic HF. The aim of this study was to determine the epidemiological, clinical, and inflammatory risk factors associated with seronegative or seropositive HF patients. Methods: We performed a cross-sectional study in the Venezuelan central-west states among a healthy rural population and in patients admitted to the emergency room with uncompensated HF. Results: The seroprevalence rates of Trypanosoma cruzi antibodies were 11.2% and 40.1% in the healthy population and in HF patients, respectively. Seropositivity in healthy individuals was associated with age, knowledge on triatomine vectors, and having seen wild reservoirs in the house; in HF patients, with contact with the vector and previous clinical diagnosis of Chagas' disease; and in both groups taken together, with age, knowledge on triatomines, and HF. Seropositive patients had prolonged QRS, decreased ejection fraction, and high serum magnesium, all significant as compared with HF seronegative cases. Left atrium enlargement and ventricular hypertrophy were most frequently observed in HF seronegative patients. CRP, IL6, ILβ1, IL2, and FNTα were elevated in 94.5%, 48%, 17.8%, 13.7%, and 6.9% of HF patients, respectively, but only IL2 levels were associated with chagasic HF. Conclusions: There is a high prevalence of aTcAg in HF patients from the central-west region of Venezuela, and their epidemiological, clinical, and inflammatory features are discreetly different as compared with those of seronegative cases.
Herrera-Martinez A.D.,University Centro Occidental Lisandro Alvarado |
Rodriguez-Morales A.J.,University of Los Andes, Venezuela |
Rodriguez-Morales A.J.,Central University of Venezuela
Tropical Biomedicine | Year: 2010
Climate change and variability is affecting human health and disease direct or indirectly through many mechanisms. Dengue is one those diseases that is strongly influenced by climate variability. In this study we assess potential associations between macroclimatic variation and dengue cases in a western pediatric hospital of Venezuela in an eight-year period. Between 2001 and 2008, 7,523 cases of dengue were reported in the Hospital Agustin Zubillaga, Barquisimeto, Venezuela. Climatic periods marked a difference of 23.15% in the mean incidence of cases, from El Niño weeks (-14.16% of cases below the mean incidence) to La Niña months (+8.99% of cases above it) (p=0.0001). Linear regression showed significantly higher dengue incidence with lower values of Oceanic Niño Index (ONI) (El Niño periods) and lower dengue incidence with higher values of ONI (La Niña periods) (p=0.0002). As has been shown herein, climate variability is an important element influencing the dengue epidemiology in Venezuela. However, it is necessary to extend these studies in this and other countries in the region, because these models can be applied for surveillance as well for prediction of dengue.
Sequera O.,University Centro Occidental Lisandro Alvarado |
Ramirez R.,Central University of Venezuela
Bioagro | Year: 2013
Phosphorus deficiency in tropical soils is a common constrain. Acidulated phosphate rock with sulfuric acid (RFA) is a natural source of P, but a cheaper alternative is the acidification of phosphate rock by replacing 30% of sulfuric acid with ammonium thiosulfate (R30T). To test the efficiency of those fertilizers and superphosphate two experiments were conducted using an acidic soil and a neutral one. The doses of P applied were 0, 70, 140 and 210 mg·kg-1. A completely randomized design was used with four replications, and cowpea plants were grown. Plants were harvested at 35 days old and dry matter (DM), P uptake, residual P and Ca in soil, and root length (RL) were determined. When RFA was applied, DM and P uptake were similar to those in R30T and SFT. DM was highly related to soil P and Ca contents as well as to P concentration in the plant. RL increased as available P was higher in the acidic soil, but not in neutral soil. It is concluded that partial acidulation of phosphate rock with ammonium thiosulfate and sulfuric acid produces a fertilizer as efficient as the RFA for growth of the root system in both acid and neutral soil, and confirmed its efficiency in the production of dry matter and phosphorus uptake by the plant.
PubMed | University of Los Andes, Venezuela, Hospital Of Chabasquen and University Centro Occidental Lisandro Alvarado
Type: Journal Article | Journal: Revista do Instituto de Medicina Tropical de Sao Paulo | Year: 2015
Chagas disease is a public health problem worldwide. The availability of diagnostic tools to predict the development of chronic Chagas cardiomyopathy is crucial to reduce morbidity and mortality. Here we analyze the prognostic value of adenosine deaminase serum activity (ADA) and C-reactive protein serum levels (CRP) in chagasic individuals. One hundred and ten individuals, 28 healthy and 82 chagasic patients were divided according to disease severity in phase I (n = 35), II (n = 29), and III (n = 18). A complete medical history, 12-lead electrocardiogram, chest X-ray, and M-mode echocardiogram were performed on each individual. Diagnosis of Chagas disease was confirmed by ELISA and MABA using recombinant antigens; ADA was determined spectrophotometrically and CRP by ELISA. The results have shown that CRP and ADA increased linearly in relation to disease phase, CRP being significantly higher in phase III and ADA at all phases. Also, CRP and ADA were positively correlated with echocardiographic parameters of cardiac remodeling and with electrocardiographic abnormalities, and negatively with ejection fraction. CRP and ADA were higher in patients with cardiothoracic index 50%, while ADA was higher in patients with ventricular repolarization disturbances. Finally, CRP was positively correlated with ADA. In conclusion, ADA and CRP are prognostic markers of cardiac dysfunction and remodeling in Chagas disease.
Juan Jose P.S.,University Centro Occidental Lisandro Alvarado
Revista Geografica Venezolana | Year: 2011
The purpose of this study is a historical reconstruction of the formation process of a new revenue distribution model and the description of its general characteristics. In 2003, legal, monetary and fiscal arrangements were configured, allowing the National Executive Branch to take over a growing piece of the international petroleum revenue (RPI) obtained from the world market. It was found that three mechanisms were used in order to impose the new arrangements: a) underestimation of the public income budget, b) PDVSA's expenses in social development; c) creation of special funds. The distribution is an essentially political action, which in the Venezuelan case, broadly speaking, followed institutional criteria until 2002. In the founded model, the revenue is distributed (hence its name) with no attachments to exact rules. Its characteristics are: discretional assignation of resources, centralization and concentration of decisions, aggrandisement of the figure of the country's President, gravitational centre of the distribution.
Torrealba R.S.,University Centro Occidental Lisandro Alvarado
General Relativity and Gravitation | Year: 2010
In this work there are proposed several new 6D brane worlds based on exact topological solutions to the vortex equations for the Abelian Higgs model, with suitable boundary conditions and symmetry breaking potentials similar to the mexican hat. Just as happens for RS domain wall brane worlds, it is shown that the massless mode of linearized gravity is localized in the neighborhood of the string-vortex solution while there are not massive bounded states. The correction to the newtonian limit of the effective 4D gravity is calculated. © 2010 Springer Science+Business Media, LLC.
Torrealba S. R.S.,University Centro Occidental Lisandro Alvarado
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010
The confinement of electromagnetic field is studied in axial symmetrical, warped, six-dimensional brane world, using a recently proposed topological Abelian string-vortex solution as background. It was found, that the massless gauge field fluctuations follow four-dimensional Maxwell equations in the Lorenz gauge. The massless zero mode is localized when the thickness of the string vortex is less than 5β/4πe2v2 and there are no other localized massless modes. There is also an infinite of nonlocalized massive Fourier modes, that follow four-dimensional Proca equations with a continuous spectrum. To compute the corrections to the Coulomb potential, a radial cutoff was introduced, in order to achieve a discrete mass spectrum. As a main result, a RoβR2 correction was found for the four-dimensional effective Coulomb law; the result is in correspondence with the observed behavior of the Coulomb potential at today's measurable distances. © 2010 The American Physical Society.
Sandoval J.P.M.,Francisco de Miranda National Experimental University |
Martinez A.E.,Technical University Territorial Alonso Gamero |
Torres D.G.,University Centro Occidental Lisandro Alvarado
Acta Agronomica | Year: 2015
The objective was to evaluate the effect of vermicompost made with California red worm (Eisenia foetida), and substrate remains of food, coffee dregs, pseudostems banana and horse dung, on the properties of a sodium-saline soil of Cebollal plain. Incubation experiment was carried out to compare three doses of vermicompost. Four treatments were implemented: treatment without vermicompost (T1); T2: 1% vermicompost; T3: 5% vermicompost and T4: 10% vermicompost, for an incubation period of 28 days, with measurements at 7, 14, 21, and 28 days. In each dates were evaluated the soil pH, electrical conductivity (EC) and exchangeable sodium percentage (ESP). All variables decreased during the trial. The EC T4 showed a reduction of 62% compared to baseline (3.48 dS/m). The application of different treatments has reduced the initial values of soil pH (8.30); the most effective treatment was T4, since soils changed from the condition of alkali to neutral soils (pH ≤ 7.5). With the application of 10% vermicompost was reduced ESP 50%. The addition of vermicompost proved to be a good strategy for the full recovery of saline-sodic soils.