Structure formation in the presence of dark energy perturbations

We study non-linear structure formation in the presence of dark energy. The influence of dark energy on the growth of large-scale cosmological structures is exerted both through its background effect on the expansion rate, and through its perturbations. In order to compute the rate of formation of massive objects we employ the spherical collapse formalism, which we generalize to include fluids with pressure. We show that the resulting non-linear evolution equations are identical to the ones obtained in the pseudo-Newtonian approach to cosmological perturbations, in the regime where an equation of state serves to describe both the background pressure relative to density, and the pressure perturbations relative to the density perturbations. We then consider a wide range of constant and time-dependent equations of state (including phantom models) parametrized in a standard way, and study their impact on the non-linear growth of structure. The main effect is the formation of dark energy structure associated with the dark matter halo: non-phantom equations of state induce the formation of a dark energy halo, damping the growth of structures; phantom models, on the other hand, generate dark energy voids, enhancing structure growth. Finally, we employ the Press-Schechter formalism to compute how dark energy affects the number of massive objects as a function of redshift (number counts).

Physical approximations for the nonlinear evolution of perturbations in inhomogeneous dark energy scenarios

The abundance and distribution of collapsed objects such as galaxy clusters will become an important tool to investigate the nature of dark energy and dark matter. Number counts of very massive objects are sensitive not only to the equation of state of dark energy, which parametrizes the smooth component of its pressure, but also to the sound speed of dark energy, which determines the amount of pressure in inhomogeneous and collapsed structures. Since the evolution of these structures must be followed well into the nonlinear regime, and a fully relativistic framework for this regime does not exist yet, we compare two approximate schemes: the widely used spherical collapse model and the pseudo-Newtonian approach. We show that both approximation schemes convey identical equations for the density contrast, when the pressure perturbation of dark energy is parametrized in terms of an effective sound speed. We also make a comparison of these approximate approaches to general relativity in the linearized regime, which lends some support to the approximations.

Bactérias coliformes totais e coliformes de origem fecal em águas usadas na dessedentação de animais

Foram colhidas 105 amostras de água sendo 44 de mananciais e de 61 bebedouros, a partir das quais foram realizadas as determinações dos NMP (Número Mais Provável) de bactérias coliformes totais e fecais. de acordo com a Portaria GM/0013 de 15 de janeiro de 1976, da Secretaria Especial do Meio Ambiente do Ministério do Interior, os 44 mananciais revelaram-se dentro dos parâmetros estabelecidos. Embora não haja referência com relação a bebedouros, aplicando-se os valores estabelecidos para mananciais, das 61 amostras estudadas, somente 6 (9,8%) não poderiam ser usadas para a dessedentação de animais. Das 105 amostras analisadas, verificou-se que as condições sanitárias revelaram-se não satisfatórias em 6 (5,7%) amostras de bebedouros quanto a coliformes fecais, sendo 3 (2,8%) também com relação a coliformes totais.

Dark energy parametrizations and their effect on dark halos

There are a plethora of dark energy parametrizations that can fit current supernovae Ia data. However, these data are only sensitive to redshifts up to order one. In fact, many of these parametrizations break down at higher redshifts. In this paper we study the effect of dark energy models on the formation of dark halos. We select a couple of dark energy parametrizations which are sensible at high redshifts and compute their effect on the evolution of density perturbations in the linear and non-linear regimes. Using the Press-Schechter formalism we show that they produce distinguishable signatures in the number counts of dark halos. Therefore, future observations of galaxy clusters can provide complementary constraints on the behaviour of dark energy.

Hemocyte types and total and differential counts in unparasitized and parasitized Anastrepha obliqua (Diptera, Tephritidae) larvae

Os tipos de hemócitos e as contagens total e diferencial foram estudados em larvas parasitadas e não parasitadas de Anastrepha obliqua pertencentes ao início e ao final da terceira fase. em ambas as fases do desenvolvimento, tanto em larvas parasitadas quanto nas não parasitadas, foram observados pró-hemócitos, plasmatócitos, granulócitos, adipo-hemócitos, esferulócitos e oenocitóides. A presença de divisões mitóticas indica os pró-hemócitos como células-tronco. Pró-hemócitos, plasmatócitos e granulócitos são as células mais numerosas na hemolinfa de A. obliqua. Foi observada diferença no número total de hemócitos entre larvas parasitadas e não parasitadas apenas no final da terceira fase.

Fine root isotropy in Eucalyptus grandis plantations. Towards the prediction of root length densities from root counts on trench walls

The objectives of the study were to assess changes in fine root anisotropy and specific root lengths throughout the development of Eucalyptus grandis ( W. Hill ex Maiden) plantations and to establish a predictive model of root length density (RLD) from root intercept counts on trench walls. Fine root densities (<1 mm in diameter) were studied in 6-, 12-, 22-, 28-, 54-, 68- and 72-month-old E. grandis plantations established on deep Ferralsols in southern Brazil. Fine root intercepts were counted on 3 faces of 90-198 soil cubes (1 dm(3) in volume) in each stand and fine root lengths (L) were measured inside 576 soil cubes, sampled between the depths of 10 cm and 290 cm. The number of fine root intercepts was counted on one vertical face perpendicular to the planting row (N(t)), one vertical face parallel to the planting row (N(l)) and one horizontal face (N(h)), for each soil cube sampled. An overall isotropy of fine roots was shown by paired Student's t-tests between the numbers of fine roots intersecting each face of soil cubes at most stand ages and soil depths. Specific root lengths decreased with stand age in the upper soil layers and tended to increase in deep soil layers at the end of the rotation. A linear regression established between N(t) and L for all the soil cubes sampled accounted for 36% of the variability of L. Such a regression computed for mean Nt and L values at each sampling depth and stand age explained only 55% of the variability, as a result of large differences in the relationship between L and Nt depending on stand productivity. The equation RLD=1.89*LAI*N(t), where LAI was the stand leaf area index (m(2) m(-2)) and Nt was expressed as the number of root intercepts per cm(2), made it possible to predict accurately (R(2)=0.84) and without bias the mean RLDs (cm cm(-3)) per depth in each stand, for the whole data set of 576 soil cubes sampled between 2 years of age and the end of the rotation.

Diurnal variation in transect counts of birds in a cerrado landscape in the state of São Paulo, Brazil

The general statement that birds are recorded more often on morning than on afternoon counts is quite common and widespread among ornithologists. Although many investigators have reported temporal variations in bird detections using Point Counts in temperate regions, few researches regarding the same objectives have been conducted in Neotropical habitats or used transect counts as field method. We used transect counts to test the hypothesis that birds are evenly recorded between times of day in a predominantly open Cerrado landscape in southeastern Brazil. Although not always significantly, the number of species and individuals were consistently greater during the morning counts, which corroborates the fact that birds can be more detectable during this time of day. However, a few families as well as a small percentage of species were more likely to be recorded during either one of the two periods we analyzed. Our results suggest that morning counts should detect higher number of both species and individuals in our study area, but specific taxa show distinct patterns of detection which should be acknowledged prior to sampling.

Comparison of two methods (visual estimates and filming) for counts of horn flies (Haematobia irritans irritans) (L.) (Diptera : Muscidae)

Visual estimates are generally used for counts of horn flies, Haematobia irritans (L.) and play an important role as an instrument to quantify fly populations in scientific studies. In this study, horn fly counts were performed on 30 Nelore steers in the municipality of Aracatuba, SP Brazil, from January to December 1998. Flies were counted weekly by two methods: the estimate method whereby estimates of the number of flies on one side of the animal are obtained by visual observation, and the filming method whereby images of flies from both sides of the animal are recorded with a video camera. The tape was then played on a videotape recorder coupled to a television and the flies were counted on the screen. Both methods showed variations in horn fly population density during the period studied. However, significant differences (p < 0.05) were observed between the two methods with the filming method permitting the visualization of a larger number of flies than the estimate method. In addition, the filming method permitted safe and reliable counts hours after the images were taken, with the advantage that the tape can serve as an archive for random re-counts. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Influence of sample type and collection method on Streptococcus mutans and Lactobacillus spp. counts in the oral cavity

Objectives: This study compared three methods of Streptococcus mutans and Lactobacillus spp. detection in the oral cavity: saliva swab (SS)-sample of stimulated saliva collected with swab; whole saliva (WS)-sample of 2 ml of stimulated saliva; and the dental plaque method (DP)-plaque sample of all dental surfaces.Methods: Thirty children were included in this study. In the first 15 children, the SS and WS methods were carried out before the dental plaque collection, and in the following 15, the sequence was inverted to evaluate possible interference of the methods sequence. The samples were diluted and inoculated in SB20 and Rogosa agar, respectively for S. mutans and Lactobacillus spp., at 37 degrees C for 48 h.Results: the results (cfu/mL) of S. mutans were analysed by the statistical Friedman's test. The levels of Lactobacillus spp. were analysed by descriptive statistics due to the high proportion of zero counts in the culture. In the first sequence of methods, the number of S. mutans counted for the SS method was inferior to DP and WS (P < 0.05), and the results for the WS and DP methods were similar. The detection of Lactobacillus spp. was observed just by the WS (100 %) and SS (14.3 %) methods. However, in the second experimental set the number of S. mutans detected by the DP method was similar to those of the SS and WS, however, the WS method showed higher values than SS (P < 0.05). A greater number of Lactobacillus spp. was detected by the WS method (100 %), followed by SS (55.5 %) and DP (33.3 %).Conclusions: the dental plaque collection and the sample of stimulated whole saliva presented similar results in the S. mutans count. The most suitable method to detect the Lactobacillus spp. level in the oral cavity is the stimulated whole saliva method. (c) 2004 Elsevier Ltd. All rights reserved.

Decrease in sperm number after treatment of rats with Austroplenckia populnea

The purpose of this study was to evaluate the effects of a hexanic extract (HE) made from leaves of A. populnea collected in Botucatu, State of São Paulo, and Nova Lima, State of Minas Gerais, Brazil, at a range of doses during 7 and 14 days, on the male reproductive system of rats. The treatment did not affect the body weight, nor absolute organ weight. The serum testosterone levels, testicular sperm head counts, daily sperm production, and sperm morphology did not differ from that of the control groups. The spermatogenesis and the morphometric parameters of cauda epididymidis were not affected by the treatment. Cauda epididymis sperm number was significantly reduced in the group that received HE of Nova Lima, 1 g/kg/day, during 14 days, from the control group. (C) 2000 Elsevier B.V. All rights reserved.

Frequency of Candida spp. in the Oral Cavity of Brazilian HIV-Positive Patients and Correlation with CD4 Cell Counts and Viral Load

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

MICROBIAL COUNTS of DARK RED LATOSOL SAMPLES STORED AT DIFFERENT TEMPERATURES

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Organization of the cysts in bee (Hymenoptera, Apidae) testis: number of spermatozoa per cyst

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of oral environment stabilization procedures on Streptococcus mutans counts in pregnant women

O objetivo desta pesquisa foi determinar o efeito da adequação do meio bucal sobre a contagem de Streptococcus mutans em gestantes de alto risco à cárie, participantes de um programa de prevenção em uma instituição de ensino público, antes e após adequação do meio bucal. Amostras de saliva de 30 gestantes (18 a 43 anos) que procuraram atendimento na Clínica de Odontologia Preventiva da FOAr-UNESP foram coletadas antes e após procedimentos de adequação do meio bucal, e examinadas para observação e contagem das UFCs de S. mutans. Foi demonstrado que houve diminuição na quantidade das UFCs (p<0,0001) entre as amostras. em relação à faixa etária, 70,0% das gestantes tinham entre 18 e 30 anos de idade e 30,0% pertenciam à faixa etária de 31 a 43 anos. Dados relativos ao período da gestação revelaram que 73,4% estavam no 2º trimestre e 13,3% estavam igualitariamente no 1º e 3º trimestres. A adequação do meio bucal se mostrou eficaz na diminuição das UFCs de S. mutans presentes na saliva de gestantes de alto risco de cárie. Este procedimento é simples e extremamente efetivo, atendendo às necessidades de tratamento básico de gestantes que procuram atendimento odontológico no serviço público de saúde.

DISTRIBUTION OF THE NUMBER OF EURYTREMA SP EGGS PER GRAM OF FECES IN NATURALLY INFECTED CATTLE

Eurytrema sp. egg counts (epg) in the feces of naturally infected cattle were performed and the technique employed showed 94.2% probability of detecting positive cases of the infection with a single examination independently of the host parasite burden. It was also demonstrated that the epg of Eurytrema sp. follows a negative binomial distribution model and is characterized by its small magnitude.