The exponentiated generalized gamma distribution with application to lifetime data

A four-parameter extension of the generalized gamma distribution capable of modelling a bathtub-shaped hazard rate function is defined and studied. The beauty and importance of this distribution lies in its ability to model monotone and non-monotone failure rate functions, which are quite common in lifetime data analysis and reliability. The new distribution has a number of well-known lifetime special sub-models, such as the exponentiated Weibull, exponentiated generalized half-normal, exponentiated gamma and generalized Rayleigh, among others. We derive two infinite sum representations for its moments. We calculate the density of the order statistics and two expansions for their moments. The method of maximum likelihood is used for estimating the model parameters and the observed information matrix is obtained. Finally, a real data set from the medical area is analysed.

Double generalized linear model for tissue culture proportion data: a Bayesian perspective

Joint generalized linear models and double generalized linear models (DGLMs) were designed to model outcomes for which the variability can be explained using factors and/or covariates. When such factors operate, the usual normal regression models, which inherently exhibit constant variance, will under-represent variation in the data and hence may lead to erroneous inferences. For count and proportion data, such noise factors can generate a so-called overdispersion effect, and the use of binomial and Poisson models underestimates the variability and, consequently, incorrectly indicate significant effects. In this manuscript, we propose a DGLM from a Bayesian perspective, focusing on the case of proportion data, where the overdispersion can be modeled using a random effect that depends on some noise factors. The posterior joint density function was sampled using Monte Carlo Markov Chain algorithms, allowing inferences over the model parameters. An application to a data set on apple tissue culture is presented, for which it is shown that the Bayesian approach is quite feasible, even when limited prior information is available, thereby generating valuable insight for the researcher about its experimental results.

Identification of microsatellites markers associated with yield components and quality parameters in sugarcane

Marker assisted selection depends on the identification of tightly linked association between marker and the trait of interest. In the present work, functional (EST-SSRs) and genomic (gSSRs) microsatellite markers were used to detect putative QTLs for sugarcane yield components (stalk number, diameter and height) and as well as for quality parameters (Brix, Pol and fibre) in plant cane. The mapping population (200 individuals) was derived from a bi-parental cross (IACSP95-3018 x IACSP93-3046) from the IAC Sugarcane Breeding Program. As the map is under construction, single marker trait association analysis based on the likelihood ratio test was undertaken to detect the QTLs. Of the 215 single dose markers evaluated (1:1 and 3:1), 90 (42%) were associated with putative QTLs involving 43 microsatellite primers (18 gSSRs and 25 EST-SSRs). For the yield components, 41 marker/trait associations were found: 20 for height, 6 for diameter and 15 for stalk number. An EST-SSRs marker with homology to non-phototropic hypocotyls 4 (NPH4) protein was associated with a putative QTL with positive effect for diameter as also with a negative effect for stalk number. In relation to the quality parameters, 18 marker trait associations were found for Brix, 19 for Pol, and 12 for fibre. For fibre, 58% of the QTLs detected showed a negative effect on this trait. Some makers associated with QTLs with a negative effect for fibre showed a positive effect for Pol, reflecting the negative correlation generally observed between these traits.

SOYBEAN YIELD COMPONENTS IN DIFFERENT SOWING PERIODS IN THE WESTERN OF STATE OF BAHIA

Yield is closely linked to the plant yield components and depend directly of the genotype interaction with the environment. Essays were installed in the experimental field of the Bahia Foundation in the Maria Gabriela farm in the county of Sao Desiderio - BA in the year 2006-2007. The aim of this work was to evaluate yield components of five soybean cultivars with different maturation cycles indicated for the Western Region of Bahia in different sowing periods. The experimental design was in random blocks in 4 x 5 factorial scheme (four sowing periods: Ep1 first - 11/29/2006, Ep2 second - 12/14/2006, Ep3 third - 12/28/2007, Ep4 fourth - 01/12/2007 and five cultivars: M-SOY 8411, BRS Corisco, BRS 263 [Diferente], BRS Barreiras e M-SOY 9350) with four repetitions. The following characteristics were evaluated: total number of pods per plant, total number of beans per plant, mass of 1000 beans and yield. Plant yield components, total number of pods per plant, total number of beans per plant, mass of 1000 beans, reduced with sowing delay and showed compensation effect between cultivars and sowing periods. Late sowing Ep3 (28/12/2006) and Ep4 (12/01/2007) were not favourable to raise yield of soybean in the Western Region of Bahia.

Spatial patterns of soil attributes and components in a mangrove system in Southeast Brazil (Sao Paulo)

Purpose Among environmental factors governing innumerous processes that are active in estuarine environments, those of edaphic character have received special attention in recent studies. With the objectives of determining the spatial patterns of soil attributes and components across different mangrove forest landscapes and obtaining additional information on the cause-effect relationships between these variables and position within the estuary, we analyzed several soil attributes in 31 mangrove soil profiles from the state of So Paulo (Guaruja, Brazil). Materials and methods Soil samples were collected at low tide along two transects within the CrumahA(0) mangrove forest. Samples were analyzed to determine pH, Eh, salinity, and the percentages of sand, silt, clay, total organic carbon (TOC), and total S. Mineralogy of the clay fraction (< 2 mm) was also studied by X-ray diffraction analysis, and partitioning of solid-phase Fe was performed by sequential extraction. Results and discussion The results obtained indicate important differences in soil composition at different depths and landscape positions, causing variations in physicochemical parameters, clay mineralogy, TOC contents, and iron geochemistry. The results also indicate that physicochemical conditions may vary in terms of different local microtopographies. Soil salinity was determined by relative position in relation to flood tide and transition areas with highlands. The proportions of TOC and total S are conditioned by the sedimentation of organic matter derived from vegetation and by the prevailing redox conditions, which clearly favored intense sulfate reduction in the soils (similar to 80% of the total Fe is Fe-pyrite). Particle-size distribution is conditioned by erosive/deposition processes (present and past) and probably by the positioning of ancient and reworked sandy ridges. The existing physicochemical conditions appear to contribute to the synthesis (smectite) and transformation (kaolinite) of clay minerals. Conclusions The results demonstrate that the position of soils in the estuary greatly affects soil attributes. Differences occur even at small scales (meters), indicating that both edaphic (soil classification, soil mineralogy, and soil genesis) and environmental (contamination and carbon stock) studies should take such variability into account.

Components of Surface Charge in Tropical Soils With Contrasting Mineralogies

Study of surface electric charges of soil colloids helps in understanding the physicochemical phenomena that influence the capacity of retaining nutrients and their availability to plants. The structural charge (sigma(0), (min)), the variable charge (sigma(q, min)), and the organic matter (OM) charge (sigma(total) (OM)) of 12 tropical soils with contrasting mineralogies were evaluated based on the difference of selectivity for Cs(+) and Li(+) between the functional ionizable surfaces groups and the mineral 2:1 siloxane surface. Soils were divided into three groups: G1, soils with a predominance of kaolinite and gibbsite in the clay fraction; G2, soils with hydroxy-interlayered 2:1 minerals; and G3, soils with smectite but without hydroxy-interlayered 2:1 minerals. The Cs absorption method was efficient for detecting the charge components in tropical soils. The mineral structural charge contributed 11% and 16%, 28% and 31%, and 52% and 59% of total soil charge of A and B horizons of soils from groups G 1, G2, and G3, respectively. On the other hand, OM contributed 53% and 37%, 48% and 41%, and 21% and 20% of total charge for the same samples, respectively, In highly weathered soils of group G I and, to a lesser extent, in soils in group G2, surface charges depended mainly on their variable components, resulting from the OM (sigma(toal) (OM)), as well as from imperfections found in 1:1 minerals (sigma(q, min)). The importance of OM in determining the magnitude of electric charges in humid tropical soils is highlighted.

Interaction Between Polar Components and the Degree of Unsaturation of Fatty Acids on the Oxidative Stability of Emulsions

Minor components (polar components) and the degree of unsaturation of the fatty acids are the main factors responsible for the oxidative stability of bulk oils and emulsions. The isolated effects of these two factors and their interaction were evaluated in oil-in-water emulsions stored at 32 A degrees C. Samples of coconut, olive, soybean, linseed and fish oils, both full and stripped of their polar components, were used to prepare the emulsions (1% w/w). The maximum concentration of hydroperoxide (LOOH(max)) and the rate of formation of hydroperoxides (mu mol L(-1) h(-1)) were used to measure the primary products. Hexanal, propanal and malondialdehyde were used to determine the secondary products of the oxidized emulsions containing polyunsaturated fatty acids. LOOH(max) varied from 0.16 to 12.75 mmol/kg among the samples. The interaction between the polar components and the degree of unsaturation of the fatty acids was significant (p < 0.001) when the hydroperoxides were evaluated. In general, the degree of unsaturation (beta(1)) and the absence of polar components (beta(2)), respectively, represented 30 and 20% of the contribution to increase the mean oxidation, with the interaction (beta(12)) contribution being more sensitive to the rate of formation of hydroperoxides (16%) than to the LOOH(max) (5%). The significance of this interaction suggests that both strategies present synergism and should be applied to improve the oxidative stability of food emulsions.

Hydrolysis Influence on Phytochemical Composition, Antioxidant Activity, Plasma Concentration, and Tissue Distribution of Hydroethanolic Ilex paraguariensis Extract Components

The infusion of aerial parts of Ilex paraguariensis is widely consumed. Its antioxidant activity suggests an important role of this plant in the treatment/prevention of oxidative stress related diseases. Plant extract active compounds are frequently found in esterified form that may be poorly absorbed. Hydrolysis of the extract is a possible approach to increase its bioavailability. The aim of this study was to perform a phytochemical analysis and evaluate in rats the plasma concentration and tissue distribution of antioxidant compounds in the hydroethanolic extract of Ilex paraguariensis, before and after enzymatic hydrolysis. Both extracts presented high antioxidant activity and phenolic content. Rats given single or repeated doses of the hydrolyzed extract showed increased plasma antioxidant activity and higher plasma levels of caffeic acid. However, no changes of endogenous antioxidants were observed. In conclusion, hydrolysis of the extract of Ilex paraguariensis is a strategy to improve its bioavailability and in vivo antioxidant activity.

Ultrasound-assisted synthesis of symmetrical biaryls by palladium-catalyzed detelluration of 1,2-diaryiditellanes

An ultrasound-assisted synthesis of functionalized symmetrical biaryls with electron-withdrawing or electron-donating substituents is described and illustrated by the palladium-catalyzed detelluration of 1,2-diarylditellanes. This procedure offers easy access to symmetrical biaryls in short reaction time and the products are achieved in good to excellent yields. (c) 2009 Published by Elsevier Ltd.

Ultrasound-Assisted Synthesis of Symmetrical Biaryls by Palladium-Catalyzed Homocoupling of Aryl n-Butyl Tellurides

An ultrasound-assisted synthesis of symmetrical biaryls with electron-withdrawing or -donating substituents is described and illustrated by palladium-catalyzed homocoupling reaction of aryl tellurides. This procedure offers easy access to biaryls in short reaction time, and the products are achieved in good to excellent yields.

Copper salt-catalyzed homo-coupling reaction of potassium alkynyltrifluoroborates: a simple and efficient synthesis of symmetrical 1,3-diynes

The copper-catalyzed dimerization of alkynyltrifluoroborates proceeds readily with good yields. The homo-coupling reaction can be effected in DMSO, in the open air, using Cu(OAc)(2) as catalyst in the absence of any other additives. A variety of functional groups are tolerated. (C) 2008 Elsevier Ltd. All rights reserved.

Classical and alternative components of the mitochondrial respiratory chain in pathogenic fungi as potential therapeutic targets

The frequency of opportunistic fungal infection has increased drastically, mainly in patients who are immunocompromised due to organ transplant, leukemia or HIV infection. In spite of this, only a few classes of drugs with a limited array of targets, are available for antifungal therapy. Therefore, more specific and less toxic drugs with new molecular targets is desirable for the treatment of fungal infections. In this context, searching for differences between mitochondrial mammalian hosts and fungi in the classical and alternative components of the mitochondrial respiratory chain may provide new potential therapeutic targets for this purpose.

Synthesis of symmetrical 1,3-diynes via homocoupling reaction of n-butyl alkynyltellurides

An ultrasound-assisted synthesis of symmetrical 1,3-diyne compounds with electron-withdrawing or donating substituents is described and illustrated by the palladium-catalyzed homocoupling reaction of n-butyl alkynyltellurides. This procedure offers easy access to 1,3-diynes in very short reaction times, and the products are achieved in good to excellent yields. (C) 2009 Elsevier Ltd. All rights reserved.

Sampling phylogenetic tree space with the generalized Gibbs sampler

The generalized Gibbs sampler (GGS) is a recently developed Markov chain Monte Carlo (MCMC) technique that enables Gibbs-like sampling of state spaces that lack a convenient representation in terms of a fixed coordinate system. This paper describes a new sampler, called the tree sampler, which uses the GGS to sample from a state space consisting of phylogenetic trees. The tree sampler is useful for a wide range of phylogenetic applications, including Bayesian, maximum likelihood, and maximum parsimony methods. A fast new algorithm to search for a maximum parsimony phylogeny is presented, using the tree sampler in the context of simulated annealing. The mathematics underlying the algorithm is explained and its time complexity is analyzed. The method is tested on two large data sets consisting of 123 sequences and 500 sequences, respectively. The new algorithm is shown to compare very favorably in terms of speed and accuracy to the program DNAPARS from the PHYLIP package.

The Reflectance Signature of Canopy Components: Implications for the Interpretation of Remotely Sensed Images

The reflectance signatures of plantation pine canopy and understorey components were measured using a spectro-radiometer. The aim was to establish whether differences observed in the reflectance signature of stressed and unstressed pine needles were consistent with observed differences in the reflectance of multispectral Landsat Thematic Mapper (TM) images of healthy and stressed forest. Because overall scene reflectance includes the contribution of each scene component, needle reflectance may not be representative of canopy reflectance. In this investigation, a limited dataset of reflectance signatures from stressed and unstressed needles confirmed the negative relationship between pine needle health and reflectance which was observed in visible red wavelengths. However, the reflectance contribution from bushes, pine needle litter and bare soil tended to reinforce this relationship suggesting that in this instance, overall scene reflectance is comprised of the proportional reflectance of each scene component. In near infrared wavelengths, differences between healthy and stressed needle reflectance suggested a strong positive relationship between reflectance and tree health. For Landsat TM images, previous research had only observed a weak positive relationship between stand health and near infrared reflectance in these pine canopies. This suggests that for multispectral Landsat TM images, reflectance of near infrared light from pine canopies may be affected by other factors which may include the scattering of light within canopies. These results are seen as promising for the use of hyperspectral images to detect stand health, provided that pixel reflectance is not influenced by other scene components.