Supressão das anomalias de fase e batimentos laterais em espectros de RMN 13c obtidos com a sequência de precessão livre no estado estacionário

The Steady-State Free Precession (SSFP) sequence has been widely used in low-field and low-resolution imaging NMR experiments to increase the signal-to-noise ratio (s/n) of the signals. Here, we analyzed the Scrambled Steady State - SSS and Unscrambled Steady State - USS sequences to suppress phase anomalies and sidebands of the 13C NMR spectrum acquired in the SSFP regime. The results showed that the application of the USS sequence allowed a uniform distribution of the time interval between pulses (Tp), in the established time range, allowing a greater suppression of phase anomalies and sidebands, when compared with the SSS sequence.

Estudo de filtros RC para baixas e altas freqüências por meio de um circuito para superposição de sinais

Apresentamos nesse trabalho, um experimento realizado nos Laboratórios didáticos do Instituto de Física da USP, relacionado ao estudo do funcionamento de filtros RC para baixas e altas freqüências. Para tal, foi especialmente projetado um circuito que efetua a superposição de um sinal gerado internamente, a uma onda senoidal externa. Várias situações experimentais podem ser geradas, por meio da variação da freqüência, tanto do sinal interno quanto da onda senoidal externa. Um estudo das componentes de freqüência de Fourier é também realizado para se estabelecer os parâmetros de funcionamento dos filtros. O funcionamento dos circuitos como integradores e diferenciadores também é explorado. Os estudantes são, portanto, levados a compreender a eficácia desses filtros mais simples, dependendo das freqüências dos sinais de entrada e correspondentes componentes de Fourier, e das freqüências de corte estabelecidas.

Evaluation of a simple hyphenated system for flow injection solid-phase pre-concentration and capillary electrophoresis

In this work, the development and evaluation of a hyphenated flow injection-capillary electrophoresis system with on-line pre-concentration is described. Preliminary tests were performed to investigate the influence of flow rates over the analytical signals. Results revealed losses in terms of sensitivity of the FIA-CE system when compared to the conventional CE system. To overcome signal decrease and to make the system more efficient, a lower flow rate was set and an anionic resin column was added to the flow manifold in order to pre-concentrate the analyte. The pre-concentration FIA-CE system presented a sensitivity improvement of about 660% and there was only a small increase of 8% in total peak dispersion. These results have confirmed the great potential of the proposed system for many analytical tasks especially for low concentration samples.

Production of DNA microarray and expression analysis of genes from Xylella fastidiosa in different culture media

DNA Microarray was developed to monitor the expression of many genes from Xylella fastidiosa, allowing the side by-side comparison of two situations in a single experiment. The experiments were performed using X. fastidiosa cells grown in two culture media: BCYE and XDM2. The primers were synthesized, spotted onto glass slides and the array was hybridized against fluorescently labeled cDNAs. The emitted signals were quantified, normalized and the data were statistically analyzed to verify the differentially expressed genes. According to the data, 104 genes were differentially expressed in XDM2 and 30 genes in BCYE media. The present study showed that DNA microarray technique efficiently differentiate the expressed genes under different conditions.

Heartworm (Dirofilaria immitis) disease in a Brazilian oncilla (Leopardus tigrinus)

Heartworm disease is caused by the intravascular nematode Dirofilaria immitis, a pathogen of public health importance usually associated to domestic dogs and cats, and to a lesser extend to other mammal species. The oncilla (Leopardus tigrinus) is a threatened neotropic felid species that naturally occurs in Brazil. Here, we report the encounter of adult and larval stages of heartworms in a female specimen of L. tigrinus, probable of free-ranging origin, from Ubatuba, São Paulo, Brazil, which died showing clinical signals compatible with heartworm disease. This was the first reported case of D. immitis infection and associated disease in L. tigrinus, also suggesting that the oncilla acted as a definitive host for this parasite. The present findings confirmed D. immitis as a pathogenic agent for this felid species, thus supporting the recommendation for the inclusion of diagnostic testing for this pathogen in routine health screening procedures for captive and free-ranging oncillas in Brazil, especially in those localities where climate conditions support the occurrence of the parasite. Potential reservoirs as oncillas are established beyond the reach of veterinary care, thus representing a continuing risk for domestic animals and humans acquiring heartworm infection. We encourage further serologic and molecular studies aiming to establish D. immitis prevalences in L. tigrinus and other wild carnivores in the region of Ubatuba, as well as ecological and veterinary studies to access the role of this pathogen for the survival of this threatened felid species.

A fuzzy reed-frost model for epidemic spreading

In this paper, we present a fuzzy approach to the Reed-Frost model for epidemic spreading taking into account uncertainties in the diagnostic of the infection. The heterogeneities in the infected group is based on the clinical signals of the individuals (symptoms, laboratorial exams, medical findings, etc.), which are incorporated into the dynamic of the epidemic. The infectivity level is time-varying and the classification of the individuals is performed through fuzzy relations. Simulations considering a real problem with data of the viral epidemic in a children daycare are performed and the results are compared with a stochastic Reed-Frost generalization

Cuidado à saúde de crianças Kaiowá e Guarani: notas de observação de campo

Inicia-se uma discussão sobre as práticas de saúde e cuidado utilizadas pelos Kaiowá e Guarani da Terra Indígena de Caarapó no enfrentamento das doenças diarréicas na infância. Utilizou-se de uma contribuição etnográfica, através do uso da técnica da observação participante e de entrevistas aberta com moradores da comunidade. Em se tratando de uma sociedade que vivencia permanentes transformações de ordem social advindas das relações interétnicas e da sucessiva presença dos serviços de saúde, observa-se que o significado de diarréia infantil, assim como as decisões relativas à prevenção e ao seu tratamento, refletem comportamentos diferenciados e complexos. A diarréia, também conhecida como chiri, é definida através de sinais que, de certa forma, são semelhantes aos biomédicos. No entanto, nem sempre as explicações de causalidade e as formas de tratamento seguem, unicamente, a abordagem biomédica. A variedade de causas da doença diarréica entre as crianças indígenas implica na escolha do processo terapêutico, que pode ser desde a procura por um especialista tradicional, realização de chás e infusões e, ainda, procura pelos serviços de saúde. Tais explicações e formas de tratamento pressupõem a existência de um processo de negociação entre pessoas de uma mesma cultura e de culturas distintas. Neste sentido, os serviços de saúde ao tratar a criança com diarréia, devem considerar não apenas a perspectiva biomédica, mas também dialogar com a percepção e as práticas indígenas na identificação da causalidade, na definição do diagnóstico e do tratamento, sobretudo, pela coexistência destas práticas no contexto local

Multifractality in plasma edge electrostatic turbulence

Plasma edge turbulence in Tokamak Chauffage Alfven Bresilien (TCABR) [R. M. O. Galvao et al., Plasma Phys. Contr. Fusion 43, 1181 (2001)] is investigated for multifractal properties of the fluctuating floating electrostatic potential measured by Langmuir probes. The multifractality in this signal is characterized by the full multifractal spectra determined by applying the wavelet transform modulus maxima. In this work, the dependence of the multifractal spectrum with the radial position is presented. The multifractality degree inside the plasma increases with the radial position reaching a maximum near the plasma edge and becoming almost constant in the scrape-off layer. Comparisons between these results with those obtained for random test time series with the same Hurst exponents and data length statistically confirm the reported multifractal behavior. Moreover, the persistence of these signals, characterized by their Hurst exponent, present radial profile similar to the deterministic component estimated from analysis based on dynamical recurrences. (C) 2008 American Institute of Physics.

Tool wear aspects when applying high-speed tapping on grey cast iron

Tool wear is a very important subject affecting the economics of machining, especially in tapping, since it is one of the last operations to be performed within most operation sequences. In the present study, some aspects of tapping such as the mechanisms and types of wear were investigated in taps working at conventional and high-speed cutting (HSC). Additionally, different types of coatings and cooling /lubrication conditions were used. The tapping operation (M8 x 1.25) was performed in through holes with two cutting speeds (30 and 60 m/min) in grey cast iron GG25. Lubrication conditions tested were dry and with minimal quantity of lubricant. Tap materials were manufactured by powder metallurgy and coated with (TiAl)N and with TiCN. A go-non-go gauge criterion was used to assess tool life. The wear and surface aspects of the tools and workpiece were evaluated by scanning electron microscopy and energy dissipation spectroscopy. Torque signals were also measured during the tests. The main wear mechanism observed was adhesion, although some abrasion and diffusion may also have occurred, and the main type of wear was flank wear. The adhesion of workpiece material on the tool was the main and decisive factor ending tool life. Tool coatings proved to be an efficient way to minimize adhesion. Torque signals followed the same pattern as the flank wear and no significant change was observed when the cutting speed was increased.

Design and characterization of bridged loop-gap resonators for use in electron paramagnetic resonance measurements

This paper revisits the design of L and S band bridged loop-gap resonators (BLGRs) for electron paramagnetic resonance applications. A novel configuration is described and extensively characterized for resonance frequency and quality factor as a function of the geometrical parameters of the device. The obtained experimental results indicate higher values of the quality factor (Q) than previously reported in the literature, and the experimental analysis data should provide useful guidelines for BLGR design.

Selective activation of the rectus abdominis muscle during low-intensity and fatiguing tasks

In order to understand the potential selective activation of the rectus abdominis muscle, we conducted two experiments. In the first, subjects performed two controlled isometric exercises: the curl up (supine trunk raise) and the leg raise (supine bent leg raise) at low intensity (in which only a few motor units are recruited). In the second experiment, subjects performed the same exercises, but they were required to maintain a certain force level in order to induce fatigue. We recorded the electromyographic (EMG) activities of the lower and upper portions of the rectus abdominis muscle during the exercises and used spatial-temporal and frequency analyses to describe muscle activation patterns. At low-intensity contractions, the ratio between the EMG intensities of the upper and lower portions during the curl up exercise was significantly larger than during the leg raise exercise (p = 0.02). A cross-correlation analysis indicated that the signals of the abdominal portions were related to each other and this relation did not differ between the tasks (p = 0.12). In the fatiguing condition, fatigue for the upper portion was higher than for the lower portion during the curl up exercise (p = 0.008). We conclude that different exercises evoked, to a certain degree, individualized activation of each part of the rectus abdominis muscle, but different portions of the rectus abdominis muscle contributed to the same task, acting like a functional unit. These results corroborate the relevance of varying exercise to modify activation patterns of the rectus abdominis muscle.

Synchronization of Discrete-Time Chaotic Systems in Bandlimited Channels

Over the last couple of decades, many methods for synchronizing chaotic systems have been proposed with communications applications in view. Yet their performance has proved disappointing in face of the nonideal character of usual channels linking transmitter and receiver, that is, due to both noise and signal propagation distortion. Here we consider a discrete-time master-slave system that synchronizes despite channel bandwidth limitations and an allied communication system. Synchronization is achieved introducing a digital filter that limits the spectral content of the feedback loop responsible for producing the transmitted signal. Copyright (C) 2009 Marcio Eisencraft et al.

Variations on a theme: diversification of cuticular hydrocarbons in a clade of cactophilic Drosophila

Background: We characterized variation and chemical composition of epicuticular hydrocarbons (CHCs) in the seven species of the Drosophila buzzatii cluster with gas chromatography/mass spectrometry. Despite the critical role of CHCs in providing resistance to desiccation and involvement in communication, such as courtship behavior, mating, and aggregation, few studies have investigated how CHC profiles evolve within and between species in a phylogenetic context. We analyzed quantitative differences in CHC profiles in populations of the D. buzzatii species cluster in order to assess the concordance of CHC differentiation with species divergence. Results: Thirty-six CHC components were scored in single fly extracts with carbon chain lengths ranging from C(29) to C(39), including methyl-branched alkanes, n alkenes, and alkadienes. Multivariate analysis of variance revealed that CHC amounts were significantly different among all species and canonical discriminant function (CDF) analysis resolved all species into distinct, non-overlapping groups. Significant intraspecific variation was found in different populations of D. serido suggesting that this taxon is comprised of at least two species. We summarized CHC variation using CDF analysis and mapped the first five CHC canonical variates (CVs) onto an independently derived period (per) gene + chromosome inversion + mtDNA COI gene for each sex. We found that the COI sequences were not phylogenetically informative due to introgression between some species, so only per + inversion data were used. Positive phylogenetic signal was observed mainly for CV1 when parsimony methods and the test for serial independence (TFSI) were used. These results changed when no outgroup species were included in the analysis and phylogenetic signal was then observed for female CV3 and/or CV4 and male CV4 and CV5. Finally, removal of divergent populations of D. serido significantly increased the amount of phylogenetic signal as up to four out of five CVs then displayed positive phylogenetic signal. Conclusions: CHCs were conserved among species while quantitative differences in CHC profiles between populations and species were statistically significant. Most CHCs were species-, population-, and sex-specific. Mapping CHCs onto an independently derived phylogeny revealed that a significant portion of CHC variation was explained by species' systematic affinities indicating phylogenetic conservatism in the evolution of these hydrocarbon arrays, presumptive waterproofing compounds and courtship signals as in many other drosophilid species.

A scientific note: Foragers deposit attractive scent marks in a stingless bee that does not communicate food location

National Science Foundation NSF IBN[0316697]

An empirical evaluation of imputation accuracy for association statistics reveals increased type-I error rates in genome-wide associations

Background: Genome wide association studies (GWAS) are becoming the approach of choice to identify genetic determinants of complex phenotypes and common diseases. The astonishing amount of generated data and the use of distinct genotyping platforms with variable genomic coverage are still analytical challenges. Imputation algorithms combine directly genotyped markers information with haplotypic structure for the population of interest for the inference of a badly genotyped or missing marker and are considered a near zero cost approach to allow the comparison and combination of data generated in different studies. Several reports stated that imputed markers have an overall acceptable accuracy but no published report has performed a pair wise comparison of imputed and empiric association statistics of a complete set of GWAS markers. Results: In this report we identified a total of 73 imputed markers that yielded a nominally statistically significant association at P < 10(-5) for type 2 Diabetes Mellitus and compared them with results obtained based on empirical allelic frequencies. Interestingly, despite their overall high correlation, association statistics based on imputed frequencies were discordant in 35 of the 73 (47%) associated markers, considerably inflating the type I error rate of imputed markers. We comprehensively tested several quality thresholds, the haplotypic structure underlying imputed markers and the use of flanking markers as predictors of inaccurate association statistics derived from imputed markers. Conclusions: Our results suggest that association statistics from imputed markers showing specific MAF (Minor Allele Frequencies) range, located in weak linkage disequilibrium blocks or strongly deviating from local patterns of association are prone to have inflated false positive association signals. The present study highlights the potential of imputation procedures and proposes simple procedures for selecting the best imputed markers for follow-up genotyping studies.