Modulação autonômica cardíaca após exercícios com haste oscilatória em ambos os sexos

Pós-graduação em Fisioterapia - FCT

Visualization, manipulation and force spectroscopy of cylindrical polymer brushes

The Ph.D. thesis deals with the conformational study of individual cylindrical polymer brush molecules using atomic force microscopy (AFM). Imaging combined with single molecule manipulation has been used to unravel questions concerning conformational changes, desorption behavior and mechanical properties of individual macromolecules and supramolecular structures. In the first part of the thesis (chapter 5) molecular conformations of cylindrical polymer brushes with poly-(N-isopropylacrylamide) (PNIPAM) side chains were studied in various environmental conditions. Also micelle formation of cylindrical brush-coil blockcopolymers with polyacrylic acid side chains and polystyrene coil have been visualized. In chapter 6 the mechanical properties of single cylindrical polymer brushes with (PNIPAM) side chains were investigated. Assuming that the brushes adopt equilibrium conformation on the surface, an average persistence length of lp= (29 ± 3) nm was determined by the end-to-end distance vs. contour length analysis in terms of the wormlike chain (WLC) model. Stretching experiments suggest that an exact determination of the persistence length using force extension curves is impeded by the contribution of the side chains. Modeling the stretching of the bottle brush molecule as extension of a dual spring (side chain and main chain) explains the frequently observed very low persistence length arising from a dominant contribution of the side chain elasticity at small overall contour lengths. It has been shown that it is possible to estimate the “true” persistence length of the bottle brush molecule from the intercept of a linear extrapolation of the inverse square root of the apparent persistence length vs. the inverse contour length plot. By virtue of this procedure a “true” persistence length of 140 nm for the PNIPAM brush molecules is predicted. Chapter 7 and 8 deal with the force-extension behavior of PNIPAM cylindrical brushes studied in poor solvent conditions. The behavior is shown to be qualitatively different from that in a good solvent. Force induced globule-cylinder conformational changes are monitored using “molecule specific force spectroscopy” which is a combined AFM imaging and SMFS technique. An interesting behavior of the unfolding-folding transitions of single collapsed PNIPAM brush molecules has been observed by force spectroscopy using the so called “fly-fishing” mode. A plateau force is observed upon unfolding the collapsed molecule, which is attributed to a phase transition from a collapsed brush to a stretched conformation. Chapter 9 describes the desorption behavior of single cylindrical polyelectrolyte brushes with poly-L-lysine side chains deposited on a mica surface using the “molecule specific force spectroscopy” technique to resolve statistical discrepancies usually observed in SMFS experiments. Imaging of the brushes and inferring the persistence length from a end-to-end distance vs. contour length analysis results in an average persistence length of lp = (25 ± 5) nm assuming that the chains adopt their equilibrium conformation on the surface. Stretching experiments carried out on individual poly-L-lysine brush molecules by force spectroscopy using the “fly-fishing” mode provide a persistence length in the range of 7-23 nm in reasonable accordance with the imaging results. In chapter 10 the conformational behavior of cylindrical poly-L-lysine brush-sodium dodecyl sulfate complexes was studied using AFM imaging. Surfactant induced cylinder to helix like to globule conformational transitions were observed.

Minimizing the Threat of a Positive Majority Deficit in Two-tier Voting Systems with Equipopulous Units

The mean majority deficit in a two-tier voting system is a function of the partition of the population. We derive a new square-root rule: For odd-numbered population sizes and equipopulous units the mean majority deficit is maximal when the member size of the units in the partition is close to the square root of the population size. Furthermore, within the partitions into roughly equipopulous units, partitions with small even numbers of units or small even-sized units yield high mean majority deficits. We discuss the implications for the winner-takes-all system in the US Electoral College.

Tracking of plasma lipids and lipoproteins, within-person and year-to-year variability in plasma cholesterol levels among participants from age 8 to 18 in Project HeartBeat!

Coronary heart disease remains the leading cause of death in the United States and increased blood cholesterol level has been found to be a major risk factor with roots in childhood. Tracking of cholesterol, i.e., the tendency to maintain a particular cholesterol level relative to the rest of the population, and variability in blood lipid levels with increase in age have implications for cholesterol screening and assessment of lipid levels in children for possible prevention of further rise to prevent adulthood heart disease. In this study the pattern of change in plasma lipids, over time, and their tracking were investigated. Also, within-person variance and retest reliability defined as the square root of within-person variance for plasma total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides and their relation to age, sex and body mass index among participants from age 8 to 18 years were investigated. ^ In Project HeartBeat!, 678 healthy children aged 8, 11 and 14 years at baseline were enrolled and examined at 4-monthly intervals for up to 4 years. We examined the relationship between repeated observations by Pearson's correlations. Age- and sex-specific quintiles were calculated and the probability of participants to remain in the uppermost quintile of their respective distribution was evaluated with life table methods. Plasma total cholesterol, HDL-C and LDL-C at baseline were strongly and significantly correlated with measurements at subsequent visits across the sex and age groups. Plasma triglyceride at baseline was also significantly correlated with subsequent measurements but less strongly than was the case for other plasma lipids. The probability to remain in the upper quintile was also high (60 to 70%) for plasma total cholesterol, HDL-C and LDL-C. ^ We used a mixed longitudinal, or synthetic cohort design with continuous observations from age 8 to 18 years to estimate within person variance of plasma total cholesterol, HDL-C, LDL-C and triglycerides. A total of 5809 measurements were available for both cholesterol and triglycerides. A multilevel linear model was used. Within-person variance among repeated measures over up to four years of follow-up was estimated for total cholesterol, HDL-C, LDL-C and triglycerides separately. The relationship of within-person and inter-individual variance with age, sex, and body mass index was evaluated. Likelihood ratio tests were conducted by calculating the deviation of −2log (likelihood) within the basic model and alternative models. The square root of within-person variance provided the retest reliability (within person standard deviation) for plasma total cholesterol, HDL-C, LDL-C and triglycerides. We found 13.6 percent retest reliability for plasma cholesterol, 6.1 percent for HDL-cholesterol, 11.9 percent for LDL-cholesterol and 32.4 percent for triglycerides. Retest reliability of plasma lipids was significantly related with age and body mass index. It increased with increase in body mass index and age. These findings have implications for screening guidelines, as participants in the uppermost quintile tended to maintain their status in each of the age groups during a four-year follow-up. The magnitude of within-person variability of plasma lipids influences the ability to classify children into risk categories recommended by the National Cholesterol Education Program. ^

Frankliniella occidentalis (Pergande)

Las trampas adhesivas habitualmente se emplean para monitoreo pero como las de mayor tamaño también se recomiendan para control, se examinó el efecto del tamaño de las amarillas en la captura total de Frankliniella occidentalis. En pimiento en floración se utilizaron trampas de 5 tamaños en un diseño de bloques al azar (n = 10), replicado 5 veces. La comparación de la captura en ambas caras de la placa, mediante la prueba t-pareada, arrojó diferencias significativas en el 96 % de las pruebas. Los datos fueron separados para los análisis posteriores. La diferencia en la captura/cm2 entre los tamaños de trampa se comparó mediante ANOVA y Tukey. Por no registrarse diferencias significativas en el 90 % de los ensayos la eficacia de todos los tamaños fue similar. La captura total se ajustó al modelo de regresión: log Y = b log X + log a siendo Y = número de insectos capturados y X = medida lineal de su tamaño (raíz cuadrada de la superficie). El ajuste al modelo fue significativo y la pendiente se aproximó a 2. Por lo tanto, la captura total fue proporcional a la superficie total, no al perímetro ni a la relación perímetro/superficie. La utilización de trampas grandes resultaría antieconómica dado su dudosa eficacia como sistema de control.

Downhole variations in grain sizes at DSDP/ODP Hole 504B

The maximum grain sizes of plagioclase and magnetite in the groundmass of the sheeted dike complex drilled at Hole 504B have been measured. Downhole variations through a 440-m-long section show a crude zig-zag pattern consisting of a gradual decrease or increase followed by an abrupt jump. The gradual decrease or increase in grain size extends over many lithologic units, and hence, does not reflect variations in grain size within a single dike. Such a zig-zag pattern is well explained by grain-size variations through multiple dikes. By using the observed inclination of sheeted dikes of 81° ± 2.5°, thickness of the multiple dikes varies from 0.7 to 8.5 m and averages to 4 ± 1 m. The average thickness of individual dikes forming multiple dikes is 0.8 m. We expect such multiple dikes to be formed during rifting events beneath mid-oceanic spreading ridges. If the average expansion at rifting episodes is twice as wide as the average width of the multiple dike units, the full spreading rate of 7.2 cm/yr of Cocos Ridge gives 112 ± 33 yr for a time interval of the rifting. A simple one-dimensional conductive cooling model is applied to solidification of multiple dikes. Numerical simulations show that the grain-size variations observed through the drill hole are more consistent with a model where a new injection of a dike occurs periodically with a constant time interval rather than one where the next dike intrudes just after the solidification of the previous one. Grain-size variations within simple dikes from Iritono, Japan, and those for Makaopuhi lava lake, Hawaii, show that square root of crystallization time is linearly correlated with the logarithm of plagioclase size. By using an empirically derived relationship between these two variables, the variations of plagioclase size through Hole 504B are directly compared with the calculated times for crystallization. Each rifting episode at the Costa Rica Rift lasts for several years, and periodic injection of a new dike occurs into the center of a previously solidified multiple dike at time intervals varying from 1 to 12 months.

Electric current of an electrified jet issuing from a long metallic tube.

This paper presents an analysis of the transport of electric current in a jet of an electrically conducting liquid discharging from a metallic tube into a gas or a vacuum, and subject to an electric field due to a high voltage applied between the tube and a far electrode. The flow, the surface charge and the electric field are computed in the current transfer region of the jet, where conduction current in the liquid becomes surface current due to the convection of electric charge accumulated at its surface. The electric current computed as a function of the flow rate of the liquid injected through the tube increases first as the square root of this flow rate, levels to a nearly constant value when the flow rate is increased and finally sets to a linear increase when the flow rate is further increased. The current increases linearly with the applied voltage at small and moderate values of this variable, and faster than linearly at high voltages. The characteristic length and structure of the current transfer region are determined. Order-of-magnitude estimates for jets which are only weakly stretched by the electric stresses are worked out that qualitatively account for some of the numerical results.

Diffusion of Zn into GaAs and AlGaAs from isothermal Liquid-phase epitaxy solutions

In this work we present results of zinc diffusion in GaAs using the liquid phase epitaxy technique from liquid solutions of Ga‐As‐Zn and Ga‐As‐Al‐Zn. Using silicon‐doped n‐GaAs substrates, working at a diffusion temperature of 850 °C, and introducing a dopant concentration ranging 1018–1019 cm−3, the most important findings regarding the diffusion properties are as follows: (a) zinc concentration in the solid depends on the square root of zinc atomic fraction in the liquid; (b) the diffusion is dominated by the interstitial‐substitutional process; (c) the diffusivity D varies as about C3 in the form D=2.9×10−67C3.05; (d) aluminum plays the role of the catalyst of the diffusion process, if it is introduced in the liquid solution, since it is found that D varies as (γAsXlAs)−1; (e) the zinc interstitial is mainly doubly ionized (Zn++i); (f) the zinc diffusion coefficient in Al0.85 Ga0.15 As is about four times greater than in GaAs; (g) by means of all these results, it is possible to control zinc diffusion processes in order to obtain optimized depth junctions and doping levels in semiconductor device fabrication.

Qualitative operational risk software -development of a software tool for determining the root of operational risk

This article shows software that allows determining the statistical behavior of qualitative data originating surveys previously transformed with a Likert’s scale to quantitative data. The main intention is offer to users a useful tool to know statistics' characteristics and forecasts of financial risks in a fast and simple way. Additionally,this paper presents the definition of operational risk. On the other hand, the article explains different techniques to do surveys with a Likert’s scale (Avila, 2008) to know expert’s opinion with the transformation of qualitative data to quantitative data. In addition, this paper will show how is very easy to distinguish an expert’s opinion related to risk, but when users have a lot of surveys and matrices is very difficult to obtain results because is necessary to compare common data. On the other hand, statistical value representative must be extracted from common data to get weight of each risk. In the end, this article exposes the development of “Qualitative Operational Risk Software” or QORS by its acronym, which has been designed to determine the root of risks in organizations and its value at operational risk OpVaR (Jorion, 2008; Chernobai et al, 2008) when input data comes from expert’s opinion and their associated matrices.

Independent and combined analyses of sequences from all three genomic compartments converge on the root of flowering plant phylogeny

Plant phylogenetic estimates are most likely to be reliable when congruent evidence is obtained independently from the mitochondrial, plastid, and nuclear genomes with all methods of analysis. Here, results are presented from separate and combined genomic analyses of new and previously published data, including six and nine genes (8,911 bp and 12,010 bp, respectively) for different subsets of taxa that suggest Amborella + Nymphaeales (water lilies) are the first-branching angiosperm lineage. Before and after tree-independent noise reduction, most individual genomic compartments and methods of analysis estimated the Amborella + Nymphaeales basal topology with high support. Previous phylogenetic estimates placing Amborella alone as the first extant angiosperm branch may have been misled because of a series of specific problems with paralogy, suboptimal outgroups, long-branch taxa, and method dependence. Ancestral character state reconstructions differ between the two topologies and affect inferences about the features of early angiosperms.

The root of the universal tree and the origin of eukaryotes based on elongation factor phylogeny.

The genes for the protein synthesis elongation factors Tu (EF-Tu) and G (EF-G) are the products of an ancient gene duplication, which appears to predate the divergence of all extant organismal lineages. Thus, it should be possible to root a universal phylogeny based on either protein using the second protein as an outgroup. This approach was originally taken independently with two separate gene duplication pairs, (i) the regulatory and catalytic subunits of the proton ATPases and (ii) the protein synthesis elongation factors EF-Tu and EF-G. Questions about the orthology of the ATPase genes have obscured the former results, and the elongation factor data have been criticized for inadequate taxonomic representation and alignment errors. We have expanded the latter analysis using a broad representation of taxa from all three domains of life. All phylogenetic methods used strongly place the root of the universal tree between two highly distinct groups, the archaeons/eukaryotes and the eubacteria. We also find that a combined data set of EF-Tu and EF-G sequences favors placement of the eukaryotes within the Archaea, as the sister group to the Crenarchaeota. This relationship is supported by bootstrap values of 60-89% with various distance and maximum likelihood methods, while unweighted parsimony gives 58% support for archaeal monophyly.

Root of the universal tree of life based on ancient aminoacyl-tRNA synthetase gene duplications.

Universal trees based on sequences of single gene homologs cannot be rooted. Iwabe et al. [Iwabe, N., Kuma, K.-I., Hasegawa, M., Osawa, S. & Miyata, T. (1989) Proc. Natl. Acad. Sci. USA 86, 9355-9359] circumvented this problem by using ancient gene duplications that predated the last common ancestor of all living things. Their separate, reciprocally rooted gene trees for elongation factors and ATPase subunits showed Bacteria (eubacteria) as branching first from the universal tree with Archaea (archaebacteria) and Eucarya (eukaryotes) as sister groups. Given its topical importance to evolutionary biology and concerns about the appropriateness of the ATPase data set, an evaluation of the universal tree root using other ancient gene duplications is essential. In this study, we derive a rooting for the universal tree using aminoacyl-tRNA synthetase genes, an extensive multigene family whose divergence likely preceded that of prokaryotes and eukaryotes. An approximately 1600-bp conserved region was sequenced from the isoleucyl-tRNA synthetases of several species representing deep evolutionary branches of eukaryotes (Nosema locustae), Bacteria (Aquifex pyrophilus and Thermotoga maritima) and Archaea (Pyrococcus furiosus and Sulfolobus acidocaldarius). In addition, a new valyl-tRNA synthetase was characterized from the protist Trichomonas vaginalis. Different phylogenetic methods were used to generate trees of isoleucyl-tRNA synthetases rooted by valyl- and leucyl-tRNA synthetases. All isoleucyl-tRNA synthetase trees showed Archaea and Eucarya as sister groups, providing strong confirmation for the universal tree rooting reported by Iwabe et al. As well, there was strong support for the monophyly (sensu Hennig) of Archaea. The valyl-tRNA synthetase gene from Tr. vaginalis clustered with other eukaryotic ValRS genes, which may have been transferred from the mitochondrial genome to the nuclear genome, suggesting that this amitochondrial trichomonad once harbored an endosymbiotic bacterium.