Showing papers by "Universidade Federal de Viçosa published in 2002"

Seasonality in CO2 and H2O flux at an eastern Amazonian rain forest

Abstract: [1] Previous studies of CO2 fluxes in Amazonia have suggested seasonal variation in net ecosystem exchange. We find little evidence of this seasonality at a new site in eastern Amazonia, despite the expectation that this site would be particularly sensitive to seasonal fluctuation of rainfall. The average rate of peak net ecosystem exchange was −19 ± 0.9 (1 S.E.) μmol CO2 m−2 s−1. Canopy conductance, evaporation, and vapour pressure deficit were all increased during the dry season, consistent with an increase in bulk temperature and solar radiation. The lack of a dry season decrease in photosynthesis was thought to be due to the observed increase in leaf area following dry season flushing. This was accompanied by an increase in solar radiation, and we suggest that the effect of “dryness” was merely to preclude optimality of photosynthetic response to this increase in radiation. The gross primary productivity of this site was estimated to be 36 t C ha−1 yr−1. This is similar to that reported for other Amazon forest stands. The year may have been a particularly productive one due to the lack of an El Nino event.

Energy and water dynamics of a central Amazonian rain forest

Abstract: [1] This paper presents measurements of the energy and water budgets of a tropical rain forest near Manaus, Brazil, in central Amazonia, collected between September 1995 and August 1996. Fluxes of sensible and latent heat were measured using a three-dimensional eddy covariance system mounted above the forest canopy. Using a new approach to analysis of eddy covariance data, we found that the measured fluxes increased significantly when turbulent transport on timescales of 1 to 4 hours was taken into account. With this new analysis, the measured turbulent fluxes almost balanced the incoming net radiation, giving increased confidence in the accuracy of the measured fluxes. Of the 5.56 GJ m−2 yr−1 of solar radiation supplied over the year, 11% were reflected, 15% were lost as net thermal emission, 27% were transported through sensible heat convection, 46% used in evapotranspiration, and 0.5% were used in net carbon fixation. Total annual evapotranspiration was calculated to be 1123 mm, accounting for 54% of total precipitation. Seasonality was an important influence: limited water availability during the dry season caused evapotranspiration to reduce by 50%. Total canopy conductance was linearly correlated to soil moisture content, with typical midday values ranging between 0.8 mol m−2 s−1 in the wet season and 0.3 mol m−2 s−1 in the dry season. Such seasonal behavior is likely to be prevalent in most tropical forest regions, and correct description of dry-season evapotranspiration will require accurate modeling of plant and soil hydraulic properties and knowledge of root distributions.

Surface water dynamics in the Amazon Basin: Application of satellite radar altimetry

Abstract: [1] Satellite radar altimetry has the ability to monitor variations in surface water height (stage) for large wetlands, rivers, and associated floodplains. A clear advantage is the provision of data where traditional gauges are absent. As part of an international program, a complete altimetric analysis of the Amazon Basin is being undertaken. Here, an updated and more rigorous evaluation of the TOPEX/POSEIDON (T/P) data set is presented for the first ∼7.5 years of the mission. With an initial study group of 230 targets, height variability at many ungauged locations can be observed for 30–50%, the range reflecting the clarity of the variations in lieu of instrument limitations. An assessment of the instrument performance confirms that the minimum river width attainable is ∼1 km in the presence of some inundated floodplain. This constraint does allow observation of the main stem (Solimoes/Amazon) and the larger tributaries, but rugged terrain in the vicinity of the target additionally places severe limitations on data retrieval. First-order validation exercises with the deduced 1992–1999 time series of stage fluctuations reveal accuracies ranging from tens of centimeters to several meters (mean ∼1.1 m rms). Altimetric water levels in the Solimoes and Amazon are particularly well defined with amplitudes <13 m and variations in peak-level timing from May to July. The water-surface gradient of the main stem is found to vary both spatially and temporally, with values ranging from 1.5 cm/km downstream to 4.0 cm/km for more upstream reaches. In agreement with ground-based estimates, the seasonal variability of the gradients reveals that the hysteresis characteristic of the flood wave varies along the main stem and the derived altimetric velocity of this flood wave is estimated to be ∼0.35 m/s. Overall, the altimetric results demonstrate that the T/P mission is successfully monitoring the transient flood waves of this continental-scale river basin.

Reaction-diffusion model for the growth of avascular tumor.

Abstract: A nutrient-limited model for avascular cancer growth including cell proliferation, motility, and death is presented. The model qualitatively reproduces commonly observed morphologies for primary tumors, and the simulated patterns are characterized by its gyration radius, total number of cancer cells, and number of cells on tumor periphery. These very distinct morphological patterns follow Gompertz growth curves, but exhibit different scaling laws for their surfaces. Also, the simulated tumors incorporate a spatial structure composed of a central necrotic core, an inner rim of quiescent cells and a narrow outer shell of proliferating cells in agreement with biological data. Finally, our results indicate that the competition for nutrients among normal and cancer cells may be a determining factor in generating papillary tumor morphology.

Parâmetros morfológicos na avaliação da qualidade de mudas de eucalyptus grandis

Abstract: An experiment was carried out to study the morphological parameters used to evaluate the quality of Eucalyptus grandis seedlings produced in different tube sizes. A mixture of 80% organic compound (CO) and 20% charcoal powder fertilized with and without N, P and K was used as substrate. Four sizes of hard plastic tubes at the volumes of 50, 110, 200 and 280 cm 3 were used as packaging. Height and height/weight relationship of the aerial part dry matter should be considered, since although providing a satisfactory contribution to seedling quality pattern, the parameters did not present a destructive process. The use of height only to estimate the quality of Eucalyptus grandis seedlings in the 110 cm 3 volume tube when they were 90-day old should be used, since it presents a satisfactory relative contribution, besides being a nondestructive, easily determined and measured parameter.

Climate‐induced changes in erosion during the 21st century for eight U.S. locations

Abstract: [1] Climate in the United States is expected to change during the 21st century, and soil erosion rates may be expected to change in response to changes in climate for a variety of reasons. This study was undertaken to investigate potential impacts of climate change on soil erosion by water. Erosion at eight locations in the United States was modeled using the Water Erosion Prediction Project model modified to account for the effects of atmospheric CO2 concentrations on plant growth. Simulated climate data from the U.K. Meteorological Office's Hadley Centre HadCM3 Global Circulation Model were used. The results indicated a complex set of interactions between the several factors that affect the erosion process. Direct effects of rainfall increases and decreases to runoff and erosion increases and decreases were observed but were often not dominant. One of the key factors of change in the system was the biomass production. Changes in soil moisture, atmospheric CO2 concentration, temperature, and solar radiation each impacted the biomass production at differing levels at the eight different sites. Different types of changes occurring at different periods of the year also complicated the response of the system. Overall, these results suggest that where precipitation increases are significant, erosion can be expected to increase. Where precipitation decreases occur, the results may be more complex due largely to interactions of plant biomass, runoff, and erosion, and either increases or decreases in overall erosion may be expected.

El Niño–Southern oscillation and the climate, ecosystems and rivers of Amazonia

Abstract: [1] The El Nino–Southern Oscillation (ENSO) phenomenon is one of the dominant drivers of environmental variability in the tropics. In this study, we examine the connections between ENSO and the climate, ecosystem carbon balance, surface water balance, and river hydrology of the Amazon and Tocantins river basins in South America. First we examine the climatic variability associated with ENSO. We analyze long-term historical climate records to document the “average” climatic signature of the El Nino and La Nina phases of the ENSO cycle. Generally speaking, the “average El Nino” is drier and warmer than normal in Amazonia, while the “average La Nina” is wetter and cooler. While temperature changes are mostly uniform through the whole year and are spatially homogeneous, precipitation changes are stronger during the wet season (January-February-March) and are concentrated in the northern and southeastern portions of the basin. Next we use a land surface/ecosystem model (IBIS), coupled to a hydrological routing algorithm (HYDRA), to examine how ENSO affects land surface water and carbon fluxes, as well as changes in river discharge and flooding. The model results suggest several responses to ENSO: (1) During the average El Nino, there is an anomalous source of CO2 from terrestrial ecosystems, mainly due to a decreased net primary production (NPP) in the north of the basin. There is also a decrease in river discharge along many of the rivers in the basin, which causes a decrease in flooded area along the main stem of the Amazon. (2) During the average La Nina, there is an anomalous sink of CO2 into terrestrial ecosystems, largely due to an increase in NPP in the northern portion of the basin. In addition, there is a large increase in river discharge in the Amazon basin, especially from the northern and western tributaries. There is a corresponding increase in flooded area, largely in the northern rivers. These results illustrate that changes in water and carbon balance associated with ENSO have complex, spatially heterogeneous features across the basin. This underscores the need for comprehensive analyses, using long-term observational data and model simulations, of regional environmental systems and their response to climatic variability.

Different regional effects of voluntary exercise on the mechanical and electrical properties of rat ventricular myocytes.

Abstract: Short-term (6 weeks) voluntary wheel running exercise in young female rats that were in an active growth phase resulted in whole-heart hypertrophy and myocyte concentric hypertrophy, when compared to sedentary controls. The cross-sectional area of ventricular myocytes from trained rats was significantly greater than for those isolated from sedentary rats, with the greatest change in morphology seen in sub-endocardial cells. There was no statistically significant effect of training on cell shortening in the absence of external mechanical loading, in [Ca2+]i transients, or in myofilament Ca2+ sensitivity (assessed during re-lengthening following tetanic stimulation). Under the external mechanical load of carbon fibres, absolute force developed in myocytes from trained rats was significantly greater than in those from sedentary rats. This suggests that increased myocyte cross-sectional area is a major contractile adaptation to exercise in this model. Training did not alter the passive mechanical properties of myocytes or the relative distribution of titin isomers, which was exclusively of the short, N2B form. However, training did increase the steepness of the active tension-sarcomere length relationship, suggesting an exercise-induced modulation of the Frank-Starling mechanism. This effect would be expected to enhance cardiac contractility. Training lengthened the action potential duration of sub-epicardial myocytes, reducing the transmural gradient in action potential duration. This observation may be important in understanding the cellular causes of T-wave abnormalities found in the electrocardiograms of some athletes. Our study shows that voluntary exercise modulates the morphological, mechanical and electrical properties of cardiac myocytes, and that this modulation is dependent upon the regional origin of the myocytes.

Are all ant mosaics caused by competition

Abstract: In this paper we tested the hypothesis that ant mosaics are generated and maintained by stochastic processes, against the general idea that deterministic processes, such as competition, are the main forces that structure these communities. We analysed 14 published ant mosaics, described for crops and natural forests, transforming their data in presence/absence matrices. These matrices were submitted to species co-occurrence analysis, using software that generates null models. The observed species co-occurrence index was then statistically compared to the null matrices, to test whether there is evidence for biological processes structuring the ant communities. From the 14 mosaics analysed, seven had less and one had more co-occurrence than expected by chance. In six mosaics, species co-occurrence was within the 95% limits of frequency distribution of randomized matrices. Even though the observation of ant spatial distribution, together with association indices between species pairs, have usually been interpreted as a result of negative interactions, our results show that in only 50% of the studied mosaics there is evidence for this explanation. Furthermore, there are alternative hypotheses to explain the result of less co-occurrence than expected by chance, besides the competition hypothesis. Association of ant species with resources and conditions may also explain the observed pattern, although these hypotheses are rarely exploited. In conclusion, competition may be an important process when studying assembly rules in ant communities, although it is certainly not the only process involved. The importance of other biological processes and of stochastic events has to be taken into account to explain the species distribution patterns.

Asymmetry in Farm to Retail Price Transmission: Evidence from Brazil

Abstract: In this article, we describe the price transmission mechanism for three groups of agricultural products in Brazil to determine if they follow the pattern found in previous studies+ These groups combine different dimensions of the two arguments normally used to explain price asymmetry: market concentration and product storability+ Results from the study area in Brazil showed that neither product storability nor market concentration were required for intense price-increase transmission+ High and increasing Brazilian inflation rates found through 1994 led the population to expect continual price increases; the society may have been able to assimilate the most intense transmissions of price increments, independent of industry market power+ Consequently, our results demonstrate that the findings from previous price transmission studies cannot be generalized to other industries or for other periods+ New theoretical and empirical studies are needed to improve our understanding of asymmetrical price transmission+ @EconLit Citations: L660, 810# © 2002 Wiley Periodicals , Inc+

Perfil socioeconômico, nutricional e de saúde de adolescentes recém-ingressos em uma universidade pública brasileira

Abstract: Objetivou-se delinear o perfil socioeconomico, nutricional e de saude de adolescentes recem-ingressos em uma universidade publica brasileira. As variaveis comportamentais foram obtidas por meio de questionario, o percentual de gordura corporal (%GC) pelo somatorio das dobras cutâneas e o estado nutricional pelo Indice de Massa Corporal. A maioria dos adolescentes era do sexo feminino (57,3%), nao residia com familiares (89,8%), consumia bebida alcoolica (73,5%), omitia alguma refeicao principal (57,3%) e rejeitava um ou mais alimentos do grupo das hortalicas (79,5%). Cerca de 57,0% nao realizavam atividade fisica e 7,0% fumavam. Em torno de 72,0% e 25,0%, respectivamente, consumiam hortalica e fruta cinco ou mais vezes na semana. Os eutroficos predominavam, mas 58,7% destes apresentavam %GC elevado. Concluiu-se que consideravel parcela dos individuos estudados residia sem os familiares e apresentava, alem de inadequacao da composicao corporal e do comportamento alimentar, outros fatores de risco a saude, como o consumo de alcool e a inatividade fisica.

Long‐term simulations of discharge and floods in the Amazon Basin

Abstract: [1] A terrestrial ecosystem model (integrated biosphere simulator (IBIS)) and a hydrological routing algorithm (HYDRA) are used in conjunction with long time series climate data to simulate the river discharge and flooded area of the Amazon/Tocantins River basin over the last 60 years. Evaluating the results of this modeling exercise over the entire basin yields three major results: (1) Observations at 121 stations throughout the basin show that discharge is well simulated for most tributaries originating in Brazil. However, the discharge is consistently underestimated, by greater than 20%, for tributaries draining regions outside of Brazil and the main stem of the Amazon. The discharge underestimation is most likely a result of underestimated precipitation in the data set used as model input. (2) A new flooding algorithm within HYDRA captures the magnitude and timing of the river height and flooded area in relatively good agreement with observations, particularly downstream of the confluence of the Negro and Solimoes Rivers. (3) Climatic variability strongly impacts the hydrology of the basin. Specifically, we find that short (∼3–4 years) and long (∼28 years) modes of precipitation variability drive spatial and temporal variability in river discharge and flooded area throughout the Amazon/Tocantins River basins.

Assessment of water systems for contaminants from domestic and industrial sewages.

Abstract: The State of Minas Gerais represents one of Brazil's most outstanding mining resources. The contamination of river water from kaolin processing activities may be harmful to people in the way of slow but chronic poisoning. On the other hand, the discharge of untreated or inadequately treated domestic sewage into aquatic environments can also cause deleterious effects to the health. However, no reliable figures are available for pollutant occurrences in river water. This draws atten- tion to the very precarious situation that exists with respect to pollution by organic and inorganic toxic wastes, especially with respect to humans and fauna in all its expressions. Thus, with the purpose of establishing a preliminary report to trace out industrialisation outcomes, samples of river water, ve- getation and fish were collected and analysed to detect pollutant inputs. The concentration of metals was determined in suspended particle, vegetation and fish, while those of nitrite, nitrate, phosphate and chloride were determined in river water samples. The concentration of dissolved oxygen (DO) was measured in river water at the time of collection. Chemical oxygen demand (COD) and biochem- ical oxygen demand (BOD) were also determined. Metal inputs in the samples analysed appeared to be related to effluent discharges into the rivers. The suspended particles showed high concentrations (in mg kg −1 ) of zinc (62 600) and aluminium (559 000), while vegetation samples collected near rivers were heavily contaminated with iron (7680). The fishes examined were contaminated with chromium (1.5 mg kg −1 ). In general, the concentrations of nitrite, nitrate, chloride, phosphate and BOD in river water were lower than the maximum values established by the Brazilian Environmental Standards.

Effects of soil water deficit and nitrogen nutrition on water relations and photosynthesis of pot-grown Coffea canephora Pierre

Abstract: Coffea canephora plants (clone INCAPER-99) were submitted to low N (LN) or high N (HN) applications and two watering regimes (daily irrigation and irrigation every 5 days for a month). Although water potential was not altered significantly by N, HN plants showed higher relative water content than did LN plants under water deficit. Only HN plants exhibited some ability for osmotic adjustment. Plants from both N treatments increased their cell wall rigidity under drought, with a more pronounced augmentation in HN plants. In well-watered plants, carbon assimilation rate increased with increasing N while stomatal conductance did not respond to N supply. Under drought conditions, carbon assimilation decreased by 68–80% compared to well-watered plants, whereas stomatal conductance and transpiration rate declined by 35% irrespective of the N applications. Stable carbon isotope analysis, combined with leaf gas exchange measurements, indicated that regardless of the watering treatments, N increased the long-term water use efficiency through changes in carbon assimilation with little or no effect on stomatal behaviour.

A velhice: algumas considerações teóricas e conceituais

Abstract: Neste artigo procede-se ao exame de algumas obras que discutem o envelhecimento, buscando analisar as diferentes perspectivas de analise: na perspectiva "biologico/comportamentalista" discutem-se aqueles estudos que se ocupam do processo de envelhecimento fisiologico Na perspectiva "economicista" analisa-se o impacto economico do envelhecimento social, discutindo questoes relativas a demanda por servicos de saude e beneficios previdenciarios Na perspectiva "sociocultural", a velhice e entendida como uma construcao social e se reflete sobre as possiveis formas de representacoes desta A quarta perspectiva, "transdisciplinar", representa uma dimensao que se esforca em contemplar o conjunto dos aspectos (biologico, economico, sociocultural) apontados nas perspectivas anteriores Considerando o grau de complexidade da realidade acerca da velhice e as dificuldades teoricas e metodologicas de contempla-la na sua totalidade, este trabalho conclui por um impasse sobre qual seria a perspectiva mais apropriada para analisa-la, e aponta para a necessidade de se ampliar e aprofundar o debate sobre as implicacoes teoricas e praticas relativas de cada perspectiva

Perdas do nitrogênio da uréia no sistema solo-planta em dois ciclos de cana-de-açúcar

Abstract: Resumo€Œ€O objetivo deste trabalho foi quantificar as perdas de N do sistema solo-cana-de-acœcar, nosciclos de cana-planta e de cana-soca. Desenvolveram-se dois experimentos em vasos de 220 L, conten-do solo de classe textural arenosa. Os€fatores de estudo do experimento com cana-planta foram doistipos de restos culturais incorporados ao solo e quatro doses de N no plantio. No€experimento comcana-soca, estudaram-se duas formas de aplicacao da urOia em superficie: sobre a palha ou sobre o solodescoberto, ou na profundidade de 15€cm, e duas fontes de K: KCl ou vinhaca. Utilizou-se urOia marcadacom

An evaluation of factors affecting the efficiency of Agrobacterium -mediated transformation of Citrus paradisi (Macf.) and production of transgenic plants containing carotenoid biosynthetic genes

Abstract: An improved protocol for Agrobacterium-mediated transformation of Duncan grapefruit (Citrus paradisi Macf.) epicotyl explants was developed by examining the effects of six different factors on the efficiency of transformation and combining the best treatment for each factor. The preculturing of explants and the composition of the cocultivation medium were the factors that most influenced transformation efficiency. The optimized protocol was successfully employed in the production of transgenic grapefruit plants containing the carotenoid biosynthetic genes phytoene synthase, phytoene desaturase, or lycopene-β-cyclase under constitutive expression. With an eventual goal of metabolically engineering grapefruit with multiple genes, hygromycin as a selectable marker and BIBAC as a transformation vector for large pieces of DNA were also tested.

Estrutura fitossocióloga de um trecho de vegetação arbórea no Parque Estadual do Rio Doce - Minas Gerais , Brasil

Abstract: The objective of the present work was to study the structure of a stand of Submontane Semi-deciduous Forest, in Rio Doce State Park (19o29'-19o48'S e 42o28'-42o38'W). In order to sample the tree component, the point-centered-quarter method was employed according to two different protocols: in one including the dead individuals, and in the other excluding them. A total of 200 sampling points were allocated in 20 parallel lines, along a hillside. A total of 143 species, belonging to 109 recognized genera and 38 botanical families was found. The main species were Bixa arborea, Guatteria schomburgkiana, Joannesia princeps, Aparisthmium cordatum, Pseudopiptadenia contorta and Carpotroche brasiliensis. The size of the populations and their distribution throughout the environment determined the prominence of these species, with the exception of P. contorta, which was represented by few large individuals. The diameter and height distributions evidenced few individuals of great size, a fact probably linked to a history of burning a 1967. The fire history and the low occurrence of climax species suggest that the forest stand studied is in a medium stage of secondary succession.

Gap-phase regeneration in a semideciduous mesophytic forest, south–eastern Brazil

Abstract: The study was carried out in ten natural canopy gaps in the Santa Genebra County Reserve (22°4945S, 47°0633W) in the county of Campinas, Sao Paulo State, Brazil. The size and canopy openness of the gaps were studied using hemispherical photographs. The vegetation survey included all shrubs and trees with height 0.50 m in the gaps interiors and all the individuals with PBH (perimeter at breast height) 15 cm in a3m surrounding border of the gaps. The similarity among the gaps and among their surrounding areas was assessed by the Jaccard similarity index and by cluster analyzes. The gap size varied from 20.09 to 468 m 2 , with a predominance of small gaps. The families with the greatest species richness in the gaps were Rutaceae, Rubiaceae and Euphorbiaceae. The species with the greatest number of individuals in the gaps were Coffea arabica L., Hybanthus atropurpureus (St. Hil.) Taub. and Actinostemon klotschii (Muell. Arg.) Pax, all widely distributed in the understorey. Shade-tolerant species (late secondary species) predominated in function of the predominance of small gaps. The high number of species found in the gaps reflects the importance of these disturbances in the maintenance of species diversity in the studied forest.

Energy intake and energy expenditure: A controlled study comparing dietitians and non-dietitians

Abstract: Background Underreporting of food intake has been commonly observed. We hypothesized that experience with recording dietary information might increase the accuracy of the records. To test this hypothesis, we compared energy intake and energy expenditure in dietitians—who are experienced in recording food intake—with those of non-dietitians, whose only exposure to training to record food was in the context of this trial. Subjects/setting Subjects for this study were 10 female registered dietitians and 10 women of comparable age and weight who were not dietitians. Design This study compared the energy intake obtained from 7-day food records with energy expenditure measured over the corresponding 7-day period using doubly labeled water. Statistical analysis Data were compared by an analysis of variance. Methods All subjects were trained to provide a 7-day weighed food intake record. Energy expenditure was measured with doubly labeled water over the 7 days when the weighed food intake record was obtained. A total of 10 dietitians and a control of group of 10 women of similar age and weight were recruited for this study. Participants were told that the goal was to record food intake as accurately as possible, because it would be compared with the simultaneous measurement of energy expenditure determined by doubly labeled water. Results : The energy expenditure of the dietitians and controls were not different (2,154±105 [mean±standard error of the mean] kcal/day for dietitians and 2,315±90kcal/ day for controls). The dietitians underreported their energy intake obtained from the food records by an average of 223±116 kcal/day, which was not different from their energy expenditure. Participants in the control group, as hypothesized, significantly underreported their energy intake (429±142kcal/day, P Conclusion Dietitians estimated their energy intake more accurately than non-dietitians, suggesting that familiarity with and interest in keeping food records may lead to more reliable estimates of energy intake. J Am Diet Assoc. 2002; 102:1428-1432 .

Responses of the photosynthetic apparatus to aluminum stress in two sorghum cultivars

Abstract: This work focused on the effects of aluminum (Al) stress on photosynthetic apparatus using Al-tolerant and sensitive cultivars of sorghum (Sorghum bicolor (L.) Moench). Plants were grown in Clark's nutrient solution aerated continuously and adjusted daily to pH 4.0 and containing two Al concentrations (0 and 185 mmol m−3) supplied as Al2(SO4)3ċ18H2O. Measurements were performed on recently expanded leaves from the eighth to sixteenth day after imposing Al treatments. In general, chloroplastidic" pigment concentration, chlorophyll fluorescence parameters, and photosynthetic rates were initially affected by Al stress to a greater extent in the Al-tolerant cultivar than in the susceptible cultivar. However, the Al-tolerant genotype seemed to cope with high Al via progressive, sustained decreases in initial chlorophyll fluorescence and increases in chlorophyll a/b ratio, photosystem II photochemical efficiency, net carbon assimilation rate, and photosynthetic oxygen evolution. In contrast, the Al-sensitive cu...

Statistical procedure to test identity between analytical methods

Abstract: The comparisons between analytical methods have been totally or partially empiric, lacking more appropriate statistical treatment. The objective of this work was to propose a statistical procedure to test the identity between analytical methods. The proposed procedure results from the combination of the F test modified from Graybill in 1976, t-test for the medium error and analysis of the linear correlation coefficient. This procedure was applied to test the identity between analytical methods in fifteen cases of comparison of an alternative analytical method in relation to standard analytical method. The results showed that the proposed statistical procedure is efficient and not subjective, and it could also be used to test the identity between any two vectors or groups of quantitative data.

Concentrações de selênio em alimentos consumidos no Brasil

Abstract: Objetivo. Determinar os teores de selenio em alimentos consumidos no Brasil. Metodos. O trabalho foi desenvolvido de 1993 a 1999. As amostras de alimentos foram coletadas no comercio varejista em varios estados do Brasil. Os teores de selenio foram determinados por meio de espectrofotometria de absorcao atomica, utilizando-se a tecnica de geracao de hidretos, e oxidacao da materia orgânica por via umida. Resultados. Os teores mais elevados de selenio foram encontrados nos produtos de origem animal, sobretudo nos pescados, e nos produtos derivados do trigo. Observou-se que os teores de selenio nos alimentos de origem vegetal foram, de modo geral, inferiores a 5,0 µg/100g. Conclusoes. No Brasil, a presenca de pescados, principalmente, e de outros produtos de origem animal e importante na dieta para garantir o consumo dos teores recomendados de selenio.

Efeito da alteração ambiental sobre comunidades de Odonata em riachos de Mata Atlântica de Minas Gerais, Brasil

Abstract: The effect of riparian deforestation and stream impoundments on an odonate community was studied in areas of surviving Atlantic forest in Vicosa and in Rio Doce State Park (PERD), Marlieria, Minas Gerais, Brazil. During 1997 16 species of Libellulidae, 4 Coenagrionidae, 2 Gomphidae, 2 Calopterygidae, 1 Megapodagrionidae, 1 Aeshnidae and 3 Protoneuridae were collected. In Vicosa, the association of sampled odonates with lotic or lentic systems, and in PERD for areas with or without riparian vegetation were compared. The results suggest that although overall odonate taxonomic richness is high in areas without riparian vegetation. Likely, because productivity increase of such areas and its invasion by lentic Odonata species.

Níveis de Proteína e Energia para Codornas Japonesas em Postura

Abstract: The experiment was conduced to determine the protein and energy levels, for laying Japanese quails (Coturnix coturnix japonica), in four experimental periods of 28 days each. Six hundred females quails with 45 days of aged and average initial weight of 138.0g were used. The experimental design used was randomized blocks, in 3x5 factorial scheme, with three levels of energy (2,850, 2,950 and 3,050 kcal of ME/kg) and five protein levels (16, 18, 20, 22 and 24% CP), with four replications of 10 animals each replications. The variables studied were: laying (%), egg weight (g), egg mass (g of eggs/quail/day), feed intake (g), feed: gain ratio (g of diet/g of eggs and g of ratio/dozen of eggs, final weight (g), shell egg percentage (%), and uric acid level in the blood serum (mg/dL). The answers of egg production quail performance, respecting the statistical adjustment obtained by means of the quadratic and linear regression models, and the biological interpretation, showed that, to obtain the best productive performance, the quails diets should contain the levels of 2,850 kcal of ME/kg of rations and 22.42% CP, corresponding to 6.02 g of protein intake by bird/day.