Two dimensional analysis of inflatable structures by the positional FEM

This paper presents a, simple two dimensional frame formulation to deal with structures undergoing large motions due to dynamic actions including very thin inflatable structures, balloons. The proposed methodology is based on the minimum potential energy theorem written regarding nodal positions. Velocity, acceleration and strain are achieved directly from positions, not. displacements, characterizing the novelty of the proposed technique. A non-dimensional space is created and the deformation function (change of configuration) is written following two independent mappings from which the strain energy function is written. The classical New-mark equations are used to integrate time. Dumping and non-conservative forces are introduced into the mechanical system by a rheonomic energy function. The final formulation has the advantage of being simple and easy to teach, when compared to classical Counterparts. The behavior of a bench-mark problem (spin-up maneuver) is solved to prove the formulation regarding high circumferential speed applications. Other examples are dedicated to inflatable and very thin structures, in order to test the formulation for further analysis of three dimensional balloons.

Aportes da gestão da informação para a criação de conhecimento em equipes de inovação

Information and knowledge have been cited for two decades as competitive advantage tools. Recently, the use of them is discussed in promotion of the innovation. The premise indicates that human interaction, information sharing and knowledge creation are vital for the success of organizations that need to learn and innovate all the time. This paper has the intention to point contributions from a dynamic environment of acquisition, dissemination and the use of information to the subsequent knowledge creation and the formation of innovation teams.

Convergence of developmental mutants into a single tomato model system: 'Micro-Tom' as an effective toolkit for plant development research

Background: The tomato (Solanum lycopersicum L.) plant is both an economically important food crop and an ideal dicot model to investigate various physiological phenomena not possible in Arabidopsis thaliana. Due to the great diversity of tomato cultivars used by the research community, it is often difficult to reliably compare phenotypes. The lack of tomato developmental mutants in a single genetic background prevents the stacking of mutations to facilitate analysis of double and multiple mutants, often required for elucidating developmental pathways. Results: We took advantage of the small size and rapid life cycle of the tomato cultivar Micro-Tom (MT) to create near-isogenic lines (NILs) by introgressing a suite of hormonal and photomorphogenetic mutations (altered sensitivity or endogenous levels of auxin, ethylene, abscisic acid, gibberellin, brassinosteroid, and light response) into this genetic background. To demonstrate the usefulness of this collection, we compared developmental traits between the produced NILs. All expected mutant phenotypes were expressed in the NILs. We also created NILs harboring the wild type alleles for dwarf, self-pruning and uniform fruit, which are mutations characteristic of MT. This amplified both the applications of the mutant collection presented here and of MT as a genetic model system. Conclusions: The community resource presented here is a useful toolkit for plant research, particularly for future studies in plant development, which will require the simultaneous observation of the effect of various hormones, signaling pathways and crosstalk.

Half-Pringle Maneuver: A Useful Tool in Laparoscopic Liver Resection

Introduction: Laparoscopic liver resections are becoming a common procedure, and bleeding remains the major concern during parenchymal transection. Total vascular inflow occlusion can be performed, but ischemic reperfusion injuries can lead to postoperative morbidity. On the other hand, hemihepatic inflow occlusion, leading to hemiliver ischemia, decreases the amount of liver parenchyma submitted to reperfusion damage and offers the advantage of reduced blood loss. Objective: The aim of this work was to describe our experience with laparoscopic the half-Pringle maneuver for segmentar or nonanatomic liver resctions. Patients and Methods: Eight patients submitted to laparoscopic liver resection in a single tertiary center. Results: There were 5 women and 3 men with a mean age of 40.2 years (range, 26-54). Mean tumor size was 4.1 cm (range, 2.6-6.0), and mean hospital stay was 3.1 days (1-5). There were 3 liver adenomas, 2 hepatocellular carcinomas, 1 metastatic melanoma, 1 metastatic colorectal carcinoma, and 1 peripheral colangiocarcinoma. No postoperative complications or mortalities were observed. Conclusions: Results demonstrate that laparoscopic liver resection with the half-Pringle maneuver is feasible and safe and may be included in the technical armamentarium of laparoscopic liver resections for a selected group of patients.

Disequilibrium Coefficient: A Bayesian Perspective

Hardy-Weinberg Equilibrium (HWE) is an important genetic property that populations should have whenever they are not observing adverse situations as complete lack of panmixia, excess of mutations, excess of selection pressure, etc. HWE for decades has been evaluated; both frequentist and Bayesian methods are in use today. While historically the HWE formula was developed to examine the transmission of alleles in a population from one generation to the next, use of HWE concepts has expanded in human diseases studies to detect genotyping error and disease susceptibility (association); Ryckman and Williams (2008). Most analyses focus on trying to answer the question of whether a population is in HWE. They do not try to quantify how far from the equilibrium the population is. In this paper, we propose the use of a simple disequilibrium coefficient to a locus with two alleles. Based on the posterior density of this disequilibrium coefficient, we show how one can conduct a Bayesian analysis to verify how far from HWE a population is. There are other coefficients introduced in the literature and the advantage of the one introduced in this paper is the fact that, just like the standard correlation coefficients, its range is bounded and it is symmetric around zero (equilibrium) when comparing the positive and the negative values. To test the hypothesis of equilibrium, we use a simple Bayesian significance test, the Full Bayesian Significance Test (FBST); see Pereira, Stern andWechsler (2008) for a complete review. The disequilibrium coefficient proposed provides an easy and efficient way to make the analyses, especially if one uses Bayesian statistics. A routine in R programs (R Development Core Team, 2009) that implements the calculations is provided for the readers.

Characterization of mitochondrial genotypes in the foundation herd of the Canchim beef cattle breed

The Canchim (5/8 Charolais + 3/8 Zebu) beef cattle breed was developed at Southeast-Embrapa Cattle to take advantage of hybrid vigor and to combine the higher growth rate and beef quality of Charolais with tropical adaptations of Zebu. The development of three lineages (old, new, and crossbred) has increased its genetic basis. The genotypic origin (Bos taurus or Bos indicus) of the mitochondrial DNA (mtDNA) of the Canchim breed was unknown. We characterized the mtDNA genotype of this founder herd by allele-specific polymerase chain reaction. The 173 founder Zebu females (62 Indubrasil, 3 Guzerat, and 108 Nellore) and their 6749 offspring were identified. The frequency of B. indicus mtDNA ranged from 1.15 to 2.05% among the descendants (N = 6404) of each maternal line with available DNA, and among animals that were alive (N = 689) in December 2007 among the three lineages. Though mtDNA characterization can be used to direct animal selection, the low frequency of B. indicus mtDNA impairs the evaluation of its effects on production traits in these animals. The high prevalence of B. taurus mtDNA in Canchim proves that the founder Zebu females from the Indubrasil, Guzerat and Nellore breeds were obtained from crosses of Zebu sires with local B. taurus dams.

Probing the Galactic thick disc vertical properties and interfaces

Aims. This work investigates the properties (metallicity and kinematics) and interfaces of the Galactic thick disc as a function of height above the Galactic plane. The main aim is to study the thick disc in a place where it is the main component of the sample. Methods. We take advantage of former astrometric work in two fields of several square degrees in which accurate proper motions were measured down to V-magnitudes of 18.5 in two directions, one near the north galactic pole and the other at a galactic latitude of 46 degrees and galactic longitude near 0 degrees. Spectroscopic observations have been acquired in these two fields for a total of about 400 stars down to magnitude 18.0, at spectral resolutions of 3.5 to 6.25 angstrom. The spectra have been analysed with the code ETOILE, comparing the target stellar spectra with a grid of 1400 reference stellar spectra. This comparison allowed us to derive the parameters effective temperature, gravity, [Fe/H] and absolute magnitude for each target star. Results. The Metallicity Distribution Function (MDF) of the thin-thick-disc-halo system is derived for several height intervals between 0 and 5 kpc above the Galactic plane. The MDFs show a decrease of the ratio of the thin to thick disc stars between the first and second kilo-parsec. This is consistent with the classical modelling of the vertical density profile of the disc with 2 populations with different scale heights. A vertical metallicity gradient, partial derivative[Fe/H]/partial derivative z = -0.068 +/- 0.009 dex kpc(-1), is observed in the thick disc. It is discussed in terms of scenarios of formation of the thick disc.

The Spleen CD4(+) T Cell Response to Blood-Stage Plasmodium chabaudi Malaria Develops in Two Phases Characterized by Different Properties

The pivotal role of spleen CD4(+) T cells in the development of both malaria pathogenesis and protective immunity makes necessary a profound comprehension of the mechanisms involved in their activation and regulation during Plasmodium infection. Herein, we examined in detail the behaviour of non-conventional and conventional splenic CD4(+) T cells during P. chabaudi malaria. We took advantage of the fact that a great proportion of CD4(+) T cells generated in CD1d(-/-) mice are I-A(b)-restricted (conventional cells), while their counterparts in I-Ab(-/-) mice are restricted by CD1d and other class IB major histocompatibility complex (MHC) molecules (non-conventional cells). We found that conventional CD4(+) T cells are the main protagonists of the immune response to infection, which develops in two consecutive phases concomitant with acute and chronic parasitaemias. The early phase of the conventional CD4(+) T cell response is intense and short lasting, rapidly providing large amounts of proinflammatory cytokines and helping follicular and marginal zone B cells to secrete polyclonal immunoglobulin. Both TNF-alpha and IFN-gamma production depend mostly on conventional CD4(+) T cells. IFN-gamma is produced simultaneously by non-conventional and conventional CD4(+) T cells. The early phase of the response finishes after a week of infection, with the elimination of a large proportion of CD4(+) T cells, which then gives opportunity to the development of acquired immunity. Unexpectedly, the major contribution of CD1d-restricted CD4(+) T cells occurs at the beginning of the second phase of the response, but not earlier, helping both IFN-gamma and parasite-specific antibody production. We concluded that conventional CD4(+) T cells have a central role from the onset of P. chabaudi malaria, acting in parallel with non-conventional CD4(+) T cells as a link between innate and acquired immunity. This study contributes to the understanding of malaria immunology and opens a perspective for future studies designed to decipher the molecular mechanisms behind immune responses to Plasmodium infection.

Design and fabrication of microcavity-array superhydrophobic surfaces

We have modeled, fabricated, and characterized superhydrophobic surfaces with a morphology formed of periodic microstructures which are cavities. This surface morphology is the inverse of that generally reported in the literature when the surface is formed of pillars or protrusions, and has the advantage that when immersed in water the confined air inside the cavities tends to expel the invading water. This differs from the case of a surface morphology formed of pillars or protrusions, for which water can penetrate irreversibly among the microstructures, necessitating complete drying of the surface in order to again recover its superhydrophobic character. We have developed a theoretical model that allows calculation of the microcavity dimensions needed to obtain superhydrophobic surfaces composed of patterns of such microcavities, and that provides estimates of the advancing and receding contact angle as a function of microcavity parameters. The model predicts that the cavity aspect ratio (depth-to-diameter ratio) can be much less than unity, indicating that the microcavities do not need to be deep in order to obtain a surface with enhanced superhydrophobic character. Specific microcavity patterns have been fabricated in polydimethylsiloxane and characterized by scanning electron microscopy, atomic force microscopy, and contact angle measurements. The measured advancing and receding contact angles are in good agreement with the predictions of the model. (C) 2010 American Institute of Physics. [doi:10.1063/1.3466979]

Novel method for measuring nanofriction by atomic force microscope

The authors describe a novel approach to the measurement of nanofriction, and demonstrate the application of the method by measurement of the coefficient of friction for diamondlike carbon (DLC) on DLC, Si on DLC, and Si on Si surfaces. The technique employs an atomic force microscope in a mode in which the tip moves only in the z (vertical) direction and the sample surface is sloped. As the tip moves vertically on the sloped surface, lateral tip slipping occurs, allowing the cantilever vertical deflection and the frictional (lateral) force to be monitored as a function of tip vertical deflection. The advantage of the approach is that cantilever calibration to obtain its spring constants is not necessary. Using this method, the authors have measured friction coefficients, for load range 0 < L M 6 mu N, of 0.047 +/- 0.002 for Si on Si, 0.0173 +/- 0.0009 for Si on DLC, and 0.0080 +/- 0.0005 for DLC on DLC. For load range 9 < L < 13 mu N, the DLC on DLC coefficient of friction increased to 0.051 +/- 0.003. (C) 2008 American Vacuum Society.

Noncommutativity due to spin

Using the Berezin-Marinov pseudoclassical formulation of the spin particle we propose a classical model of spin noncommutativity. In the nonrelativistic case, the Poisson brackets between the coordinates are proportional to the spin angular momentum. The quantization of the model leads to the noncommutativity with mixed spatial and spin degrees of freedom. A modified Pauli equation, describing a spin half particle in an external electromagnetic field is obtained. We show that nonlocality caused by the spin noncommutativity depends on the spin of the particle; for spin zero, nonlocality does not appear, for spin half, Delta x Delta y >= theta(2)/2, etc. In the relativistic case the noncommutative Dirac equation was derived. For that we introduce a new star product. The advantage of our model is that in spite of the presence of noncommutativity and nonlocality, it is Lorentz invariant. Also, in the quasiclassical approximation it gives noncommutativity with a nilpotent parameter.

Accurate prediction of the Si/SiO(2) interface band offset using the self-consistent ab initio DFT/LDA-1/2 method

We use the density functional theory/local-density approximation (DFT/LDA)-1/2 method [L. G. Ferreira , Phys. Rev. B 78, 125116 (2008)], which attempts to fix the electron self-energy deficiency of DFT/LDA by half-ionizing the whole Bloch band of the crystal, to calculate the band offsets of two Si/SiO(2) interface models. Our results are similar to those obtained with a ""state-of-the-art"" GW approach [R. Shaltaf , Phys. Rev. Lett. 100, 186401 (2008)], with the advantage of being as computationally inexpensive as the usual DFT/LDA. Our band gap and band offset predictions are in excellent agreement with experiments.

Approximation to density functional theory for the calculation of band gaps of semiconductors

The local-density approximation (LDA) together with the half occupation (transitionstate) is notoriously successful in the calculation of atomic ionization potentials. When it comes to extended systems, such as a semiconductor infinite system, it has been very difficult to find a way to half ionize because the hole tends to be infinitely extended (a Bloch wave). The answer to this problem lies in the LDA formalism itself. One proves that the half occupation is equivalent to introducing the hole self-energy (electrostatic and exchange correlation) into the Schrodinger equation. The argument then becomes simple: The eigenvalue minus the self-energy has to be minimized because the atom has a minimal energy. Then one simply proves that the hole is localized, not infinitely extended, because it must have maximal self-energy. Then one also arrives at an equation similar to the self- interaction correction equation, but corrected for the removal of just 1/2 electron. Applied to the calculation of band gaps and effective masses, we use the self- energy calculated in atoms and attain a precision similar to that of GW, but with the great advantage that it requires no more computational effort than standard LDA.

Hyper-Rayleigh scattering with picosecond pulse trains

We propose a method for measuring hyper-Rayleigh scattering employing pulse trains produced by a Q-switched and mode-locked Nd:YAG laser. The use of the entire pulse train under the Q-switch envelope avoids the need of any device to scan the irradiance, as is usually done with nanosecond and femtosecond single-pulse lasers. To verify the feasibility of the technique, we performed measurements in different solutions of para-nitroaniline and compared the results with those obtained with nanosecond pulses. In both cases, the agreement with the hyperpolarizability values reported in the literature is about the same, but the measurements carried out with pulse trains are at least 20 times faster. Besides the advantage of acquisition speed, the use of pulse trains also allows the instantaneous inspection of slow luminescence contributions arising from multiphoton absorption. (C) 2008 Optical Society of America.

Spectrally resolved femtosecond Maker fringes technique

We present a femtosecond third-harmonic generation Maker fringes technique capable of simultaneously providing the magnitude of the cubic nonlinearity and the refractive index dispersion of optical materials. This technique takes advantage of the high intensity and broad spectral band of femtosecond pulses, but requires the use of a spectrometer to deconvolute the information contained in Maker fringes produced by the broad band light. (C) 2008 American Institute of Physics.