Is there a latin american agricultural growth pattern? Ffactor endowments and productivity in the second half of the 20thcentury

In this article, we discuss whether there was a single Latin American pattern of agricultural growth between 1950 and 2008. We analyse the sources of growth of agricultural production and productivity in ten Latin American countries. Our results show that the differences between these countries are too large to establish a single pattern for this region. However, certain common trends may be observed, such as the growing importance of labour productivity as a component of agricultural production growth and the increasing relevance of total factor productivity as a component of agricultural labour productivity growth

Políticas públicas para la transformación de la educación universitaria en Venezuela durante el periodo 1999-2006

1 archivo PDF (14 páginas). magyeffiLa educación universitaria en Venezuela ha sido objeto de estudio desde diferentes perspectivas de análisis. Sin embargo, las que tienen que ver con la formación de las políticas públicas para transformar ese sector son escasas. En este sentido, explorar las políticas orientadas a la transformación de la educación universitaria en Venezuela en el periodo 1999-2006 promovidas por el Estado a través del Consejo Nacional de Universidades, es el propósito de ésta investigación. La hipótesis que se maneja es que se adelanta un modelo alternativo en el campo de la educación, en el marco de un proyecto de transformación social que busca mayor inclusión, equidad y calidad. Esta investigación se fundamenta en el análisis de documentos oficiales tales como: resoluciones, gacetas oficiales y fuentes documentales. ABSTRACT: Higher education in Venezuela has been object of study from different perspectives of analysis, however, which have to do with the formation of public policies to transform this area are scarce. In this sense, exploring the policies aimed at the transformation of the higher education in Venezuela in the period 1999-2006, promoted by the State through the National Council of Universities, is the purpose of this investigation. The hypothesis that can be handled is being pursued an alternative model in the field of education, in the framework of a project of social transformation seeking greater inclusion, equity and quality. This research is based on analysis of official documents such as: resolutions, official gazettes, and documentary sources. PALABRAS CLAVE: Estado. Educación universitaria y transformación. Estado-nación. KEYWORDS: State. Higher education and transformation. Nation-state

Trend in ice moistening the stratosphere – constraints from isotope data of water and methane

Water plays a major role in the chemistry and radiative budget of the stratosphere. Air enters the stratosphere predominantly in the tropics, where the very low temperatures around the tropopause constrain water vapour mixing ratios to a few parts per million. Observations of stratospheric water vapour show a large positive long-term trend, which can not be explained by change in tropopause temperatures. Trends in the partitioning between vapour and ice of water entering the stratosphere have been suggested to resolve this conundrum. We present measurements of stratospheric H_(2)O, HDO, CH_4 and CH_(3)D in the period 1991–2007 to evaluate this hypothesis. Because of fractionation processes during phase changes, the hydrogen isotopic composition of H_(2)O is a sensitive indicator of changes in the partitioning of vapour and ice. We find that the seasonal variations of H_(2)O are mirrored in the variation of the ratio of HDO to H_(2)O with a slope of the correlation consistent with water entering the stratosphere mainly as vapour. The variability in the fractionation over the entire observation period is well explained by variations in H_(2)O. The isotopic data allow concluding that the trend in ice arising from particulate water is no more than (0.01±0.13) ppmv/decade in the observation period. Our observations suggest that between 1991 and 2007 the contribution from changes in particulate water transported through the tropopause plays only a minor role in altering in the amount of water entering the stratosphere

Efecto de la adición de ácido cítrico y la cantidad de yeso sobre las propiedades del cemento de sulfoaluminato de calcio

The influence of citric acid on the hydration and strength development of a calcium sulphoaluminate cement was investigated. Cement pastes were prepared by mixing calcium sulphoaluminate (C4A3Ŝ) with 15, 20 and 25wt% of hemihydrate (CŜH0.5). Citric acid was added as a retarder at 0 and 0.5wt%. The samples were cured at 20 °C for periods of time from 1 to 28 days to evaluate their compressive strength and to characterize the hydration products by scanning electron microscopy and X-ray diffraction. Calorimetric curves showed that the retarding agent considerably decreases the heat release rate and the quantity of total heat released. The main product after the curing was ettringite (C6AŜ3H32). The morphology of this phase consisted of long and thin needles growing radially on the cement grains. Samples with 15wt% of hemihydrate and 0.5wt% of citric acid developed the highest compressive strength (70 MPa) at 28 days of curing.Se investigó el efecto del ácido cítrico sobre la hidratación y propiedades mecánicas de un cemento de sulfoaluminato de calcio. El C4A3Ŝ se mezcló con 15, 20 y 25% e.p. de hemihidrato (CŜH0.5). Se agregó ácido cítrico como retardante en 0 y 0.5% e.p. Las muestras fueron curadas a 20 °C por periodos de 1 a 28 días para realizar mediciones de resistencia a la compresión y caracterizar los productos de hidratación mediante microscopía electrónica de barrido y difracción de rayos X. Las curvas de calorimetría mostraron ue el ácido cítrico disminuye la velocidad de liberación de calor y la cantidad de calor liberado durante la hidratación. La resistencia a la compresión alcanzó un máximo de 70 MPa en muestras con 15% e.p. de hemihidrato y 0,5% e.p de ácido cítrico. Los resultados muestran a la etringita (C6AŜ3H32) como principal producto de hidratación. Se observa a esta fase con morfología acicular creciendo sobre las partículas de cemento

Efecto del contenido de aluminato de estroncio y hemihidrato sobre las propiedades de un cemento de sulfoaluminato de calcio

The effect of strontium aluminate (SrAl2O4) on the hydration process of a calcium sulphoaluminate (C4A3Ŝ) cement was investigated. Cement pastes were prepared by mixing C4A3Ŝ , hemihydrate (CaSO4· ½H2O, CŜH0.5) and 0, 10 or 20wt% of SrAl2O4 (SrA). The amount of CŜH0.5 was 15, 20 or 25wt% based on the C4A3Ŝ quantity. The cement pastes were hydrated using water to cement ratios (w/c) of 0.4 and 0.5. Samples were cured from 1 to 28 d. The compressive strength and setting time were evaluated and the hydration products were characterized. It was found that the setting time was delayed up to 42 min for the samples containing SrAl2O4 compared to samples without addition. The samples with 25wt% hemihydrate containing 20wt% SrAl2O4 developed the highest compressive strength (60 MPa) after 28 d of curing. The main product after hydration was ettringite (C6AŜ3H32). The morphology of this phase consisted of thin needle-shaped crystals.Se investigó el efecto de la adición de aluminato de estroncio (SrAl2O4) sobre las propiedades de un cemento de sulfoaluminato de calcio (C4A3Ŝ). Se prepararon muestras mezclando C4A3Ŝ, hemihidrato (CaSO4· ½H2O, CŜH0.5) y 0, 10 o 20% e.p de SrAl2O4 (SrA). La cantidad de CŜH0.5 fue de 15, 20 o 25% e.p. basado en la cantidad de C4A3Ŝ. Las relaciones agua/cemento utilizadas fueron 0.4 y 0.5. Las muestras fueron curadas hasta 28 d. Se evaluó el tiempo de fraguado y la resistencia a la compresión. Los productos de hidratación se caracterizaron mediante DRX y MEB. El tiempo de fraguado se retardó hasta 42 minutos con la adición del SrAl2O4 comparado con las muestras sin adiciones. Las muestras con 25% e.p. de yeso y 20% e.p. de SrAl2O4 desarrollaron la mayor resistencia a la compresión alcanzando 60 MPa a 28 d de curado. Los análisis por MEB y DRX muestran como principal producto de hidratación a la etringita (C6AŜ3H32), cuya morfología se observa como cristales aciculares

Utilization of near infrared reflectance spectroscopy for prediction of the nutritional composition of beef and pork samples

Near-infrared reflectance spectroscopy (NIRS) offers the potential for rapid, low-cost analyses of meat samples. Beef and pork samples were analyzed by both standard laboratory (AOAC) methods and NIRS. Regression equations were developed to relate the two methods. Coefficients of determination between NIRS and AOAC results were .929 for dry matter, .965 for crude protein, and .996 for ether extract. NIRS and AOAC procedures yielded very similar results (DM, 38.82 vs 38.58; CP, 17.78 vs. 17.83; and EE, 18.83 vs. 18.00). NIRS appears to be a rapid and reliable predictor of nutritional composition of ground beef and pork based on regression equations we have developed with a limited number of samples

Perspectiva conceptual normativa de la participación ciudadana y democracia en Venezuela

The conceptual approach to citizen participation and democracy in Venezuela taken in this article is extracted from the national Constitution of 1999, linking what is normative to the epistemic construction of the participatory process, with which other key concepts such as citizenship and state, are necessarily associated. The methodology that facilitates this anchoring is located in the multidisciplinary construction of discourse analysis in the social sciences, mentioning the semantics of Pottier (1992) and the semantic-pragmatic discourse analysis of Molero (1999, 2003, 2007), Conclusion: participatory democracy is the conceptual network that explicitly underlies what ought to be according to the constitution, but in practice, its contextualization varies according to the interests of the established political status quo.El abordaje conceptual de la Participación Ciudadana y de la Democracia en Venezuela que se realiza en el presente artículo se extrae desde la Constitución nacional de 1999, vinculando lo normativo con la construcción epistémica del proceso participativo, a los cuales necesariamente se le asocian otros conceptos clave como la Ciudadanía y Estado. La metodología que facilita este anclaje se ubica en la construcción multidisciplinaria del análisis del discurso en las áreas de las Ciencias Sociales, discurriendo sobre la semántica de Pottier (1992), y del análisis semántico-pragmático del discurso de Molero (1999, 2003, 2007). Se concluye: la democracia participativa es la red conceptual que subyace explícitamente desde el deber ser constitucional, pero sus contextualización en la praxis varía según los intereses del estatus quo político establecido

Relevance and social responsibility of sustainable university organizations: analysis from the perspective of endogenous capacities

The university social relevance is the effective management of the academic functions in a committed way, from which it analyzes, studies, and investigates the problems, needs, requirements of the social environment to identify, characterize, rank them. And a model social action to the research, teaching, extension, and training of professionals, consistent with social needs, linked to the realities of the various contexts of human performance that neo university organizations, rescuing sustainability with human development and socioeconomic, involving the creative potentials and indigenous innovations of society. To coexistence between community and university in favor of endogenous growth is required, conceived as the leverage from the social and organizational strengths of the human conglomerate in reference, which promote; quality of life and sustainable human progress. Consequently, the purpose of this dissertation is limited to carrying out an analysis of the relevance and social responsibility of sustainable university organizations from the endogenous perspective. From the qualitative, interpretive, and hermeneutical paradigm, the categories of analysis are reviewed, to conclude; that the university theoretically approaches endogenous development. However, it is necessary to generate links of structural-organizational configuration within the educational institutions that involve processes related to their sustainability over time and their impacts

Atmospheric greenhouse gases retrieved from SCIAMACHY: comparison to ground-based FTS measurements and model results

SCIAMACHY onboard ENVISAT (launched in 2002) enables the retrieval of global long-term column-averaged dry air mole fractions of the two most important anthropogenic greenhouse gases carbon dioxide and methane (denoted XCO_2 and XCH_4). In order to assess the quality of the greenhouse gas data obtained with the recently introduced v2 of the scientific retrieval algorithm WFM-DOAS, we present validations with ground-based Fourier Transform Spectrometer (FTS) measurements and comparisons with model results at eight Total Carbon Column Observing Network (TCCON) sites providing realistic error estimates of the satellite data. Such validation is a prerequisite to assess the suitability of data sets for their use in inverse modelling. It is shown that there are generally no significant differences between the carbon dioxide annual increases of SCIAMACHY and the assimilation system CarbonTracker (2.00 ± 0.16 ppm yr^(−1) compared to 1.94 ± 0.03 ppm yr−1 on global average). The XCO_2 seasonal cycle amplitudes derived from SCIAMACHY are typically larger than those from TCCON which are in turn larger than those from CarbonTracker. The absolute values of the northern hemispheric TCCON seasonal cycle amplitudes are closer to SCIAMACHY than to CarbonTracker and the corresponding differences are not significant when compared with SCIAMACHY, whereas they can be significant for a subset of the analysed TCCON sites when compared with CarbonTracker. At Darwin we find discrepancies of the seasonal cycle derived from SCIAMACHY compared to the other data sets which can probably be ascribed to occurrences of undetected thin clouds. Based on the comparison with the reference data, we conclude that the carbon dioxide data set can be characterised by a regional relative precision (mean standard deviation of the differences) of about 2.2 ppm and a relative accuracy (standard deviation of the mean differences) of 1.1–1.2 ppm for monthly average composites within a radius of 500 km. For methane, prior to November 2005, the regional relative precision amounts to 12 ppb and the relative accuracy is about 3 ppb for monthly composite averages within the same radius. The loss of some spectral detector pixels results in a degradation of performance thereafter in the spectral range currently used for the methane column retrieval. This leads to larger scatter and lower XCH_4 values are retrieved in the tropics for the subsequent time period degrading the relative accuracy. As a result, the overall relative precision is estimated to be 17 ppb and the relative accuracy is in the range of about 10–20 ppb for monthly averages within a radius of 500 km. The derived estimates show that the SCIAMACHY XCH_4 data set before November 2005 is suitable for regional source/sink determination and regional-scale flux uncertainty reduction via inverse modelling worldwide. In addition, the XCO2 monthly data potentially provide valuable information in continental regions, where there is sparse sampling by surface flask measurements

Single event effects in static and dynamic registers in a 0.25−μ−m0.25-\mu-m CMOS technology

We have studied single event effects in static and dynamic registers designed in a quarter micron CMOS process. In our design, we systematically used guardrings and enclosed (edgeless) transistor geometry to improve the total dose tolerance. This design technique improved both the SEL and SEU sensitivity of the circuits. Using SPICE simulations, the measured smooth transition of the cross-section curve between LET threshold and saturation has been traced to the presence of four different upset modes, each corresponding to a different critical charge and sensitive area. A new architecture to protect the content of storage cells has been developed, and a threshold LET around 89 MeV cm/sup 2/ mg/sup -1/ has been measured for this cell at a power supply voltage of 2 V