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Copyright of Revista Latinoamericana de Estudios Educativos is the property of Centro de Estudios Educativos, A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista del Centro de Investigación. Universidad La Salle is the property of Universidad La Salle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of BIOAGRO is the property of Revista BIOAGRO and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of BIOAGRO is the property of Revista BIOAGRO and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nitrogen is one of the two most important elements in the metabolism of aquatic ecosystems. At low concentrations it can limit primary productivity and when present at very high concentrations it can participate in the eutrophication process of these environments. The mechanism of nitrogen transport in sediments is almost unknown, nevertheless it is of vital importance for establishing mass balances in aquatic systems. In the study presented here, we assessed the nitrogen flux in sediments of the central part of tropical Lake Maracaibo, Venezuela, in particular with regard to dissolved oxygen concentrations. Experiments were performed under laboratory conditions in a batch system, and at varying dissolved oxygen regimes (aerobic and anaerobic). Every two days, during 3 months, overlying water samples were taken to analyze nitrite, nitrate, ammonium and Kjeldahl total nitrogen. Average release rates of total nitrogen were 0.86 in aerobic, and 1.06 mmol N m-2 d-1 in anaerobic systems corresponding to 41.7% of total N input to the lake. The behavior of nitrogen was strongly influenced by nitrate concentrations under aerobic conditions, and by organic nitrogen under anaerobic conditions during the course of the experiment. A major trend for the release of organic nitrogen during anaerobic conditions, and of nitrate, during aerobic conditions, was observed. Also fluxes of NO3-, NH4+, organic N and Total N across the sediment-water interface were measured. In anaerobic conditions, which are predominant in the hypolimnetic cone of Lake Maracaibo, denitrification was estimated to be 0.02 mmol N m-2 d-1, which corresponds to 1.89% of the total N released from sediments. This is to our knowledge the first study of nitrogen fluxes in sediments from Lake Maracaibo. The laboratory data presented here reflects conditions in the lake when major nutrients accumulation occurs. [ABSTRACT FROM AUTHOR]

Background Leprosy is a chronic infectious disease produced by Mycobacterium leprae. In 1997 Venezuela reached the goal of elimination of leprosy as a public health problem (according to the World Health Organization a prevalence rate of ≤1/10,000 inhabitants), but five states still had prevalence rates over that goal. For this study we selected Cojedes State, where prevalence rates remain over the elimination goal. Objective Evaluate the real leprosy situation in high-prevalence areas of Cojedes State. Materials and methods Seven communities of Cojedes State were selected because they had the highest historic prevalence, as well as the highest prevalence in the year to be studied (1997). Results A rank correlation using Spearman's test comparing historical prevalence rates (1946-1996) and detection rates (1998-2004) gave a statistically significant P < 0.05 value. Diagnosed leprosy cases were as follows: age: 3.2% under 15 years old; sex: male/female rates between 60% and 91.66% males. The highest number of cases were paucibacillary forms: indeterminate leprosy (33.07%) and borderline tuberculoid leprosy (32.28%); tuberculoid leprosy (7.00%); and multibacillary cases (lepromatous leprosy, LL) were only 2.36%. Bacteriologically, 18.52 patients were M. leprae positive. At the moment of diagnosis, 96.6% showed no disabilities, 3.4% showed grade I disabilities, and there were no grade II or III disabilities. Conclusion This study confirms that several communities in Cojedes State have extremely high leprosy rates. [ABSTRACT FROM AUTHOR]

School education requires the guidance, orientation and conduction of a teaching staff that is responsible for their students' development. This is why educating implies asymmetry and hierarchy, that is, pedagogical authority. However, today's societies are decreasingly hierarchical, and subjects are more critical of authority. In a sociocultural context in which the classical forms of authority are weakening, young education students have to construct new meanings which they find coherent and effective. With the goal of exploring the new understandings of pedagogical authority, a study was conducted of 913 education students in different Spanish-speaking countries: Chile, Colombia, Venezuela and Spain. The multinational analysis enabled us to identify cross-cutting meanings, as well as local understandings constructed by the education students in today's society. A questionnaire with both closed and open-ended questions was administered. The overall results indicate that viewing authority grounded in reciprocal respect between teachers and students cuts across the participants and is significantly associated with the teaching of academic knowledge. [ABSTRACT FROM AUTHOR]

This work was conducted to determine the occurrence of Trichogramma wasp species in Lara State, Venezuela. Lepidopteran egg samples collected from various crop leaves were observed daily under laboratory conditions for emergence of Trichogramma species adult wasps. Trichogramma were also obtained from traps containing eggs from the hosts Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). In the laboratory, specimens of Trichogramma species were mounted on microscope slides to show male genitalia and other morphological characters used for its identification. Trichogramma atopovirilia Oatman y Platner emerged from S. frugiperda eggs collected in a cornfield at La Palomera, Humocaro Alto and at El Parchal, Humocaro Bajo, Municipio Morán. T. atopovirilia also emerged from S. frugiperda eggs collected in a cornfield at Sabana Grande and from S. cerealella eggs used as traps in a pepper culture at Tintinal, Municipio Andrés Eloy Blanco. T. exiguum Pinto y Platner emerged from S. frugiperda eggs used as traps or collected in cornfield at Totumito and at La Palomera, Humocaro Alto. T. pretiosum Riley emerged from Phthorimaea operculella Zeller eggs collected on stored potatoes at Monte Carmelo, Sanare. The identification of Trichogramma species in Lara State would be useful in the development of biological control programs for lepidopteran pests.