Correlation between vertical misfits and stresses transmitted to implants from metal frameworks

An inappropriate prosthetic fit could cause stress over the interface implant/bone. The objective of this study was to compare stresses transmitted to implants from frameworks cast using different materials and to investigate a possible correlation between vertical misfits and these stresses. Fifteen one-piece cast frameworks simulating bars for fixed prosthesis in a model with five implants were fabricated and arranged into three different groups according to the material used for casting: CP Ti (commercially pure titanium), Co-Cr (cobalt-chromium) or Ni-Cr-Ti (nickel-chromium-titanium) alloys. Each framework was installed over the metal model with all screws tightened to a 10 N cm torque and then, vertical misfits were measured using an optical microscope. The stresses transmitted to implants were measured using quantitative photoelastic analysis in values of maximum shear stress (T), when each framework was tightened to the photoelastic model to a 10 N cm standardized torque. Stress data were statistically analyzed using one-way ANOVA and Tukey`s test and correlation tests were performed using Pearson`s rank correlation (alpha = 0.05). Mean and standard deviation values of vertical misfit are presented for CP Ti (22.40 +/- 9.05 mu m), Co-Cr (66.41 +/- 35.47 mu m) and Ni-Cr-Ti (32.20 +/- 24.47 mu m). Stresses generated by Co-Cr alloy (tau = 7.70 +/- 2.16 kPa) were significantly higher than those generated by CP Ti (tau = 5.86 +/- 1.55 kPa, p = 0.018) and Ni-Cr-Ti alloy (tau =5.74 +/- 3.05 kPa, p = 0.011), which were similar (p = 0.982). Correlations between vertical misfits and stresses around the implants were not significant as for any evaluated materials. (C) 2011 Elsevier Ltd. All rights reserved.

Measurement of the epicycle frequency in the Galactic disc and initial velocities of open clusters

A new method to measure the epicycle frequency kappa in the Galactic disc is presented. We make use of the large data base on open clusters completed by our group to derive the observed velocity vector (amplitude and direction) of the clusters in the Galactic plane. In the epicycle approximation, this velocity is equal to the circular velocity given by the rotation curve, plus a residual or perturbation velocity, of which the direction rotates as a function of time with the frequency kappa. Due to the non-random direction of the perturbation velocity at the birth time of the clusters, a plot of the present-day direction angle of this velocity as a function of the age of the clusters reveals systematic trends from which the epicycle frequency can be obtained. Our analysis considers that the Galactic potential is mainly axis-symmetric, or in other words, that the effect of the spiral arms on the Galactic orbits is small; in this sense, our results do not depend on any specific model of the spiral structure. The values of kappa that we obtain provide constraints on the rotation velocity of the in particular, V(0) is found to be 230 +/- 15 km s(-1) even if the scale (R(0) = 7.5 kpc) of the Galaxy is adopted. The measured kappa at the solar radius is 43 +/- 5 km s(-1) kpc(-1). The distribution of initial velocities of open clusters is discussed.

The intracratonic Caraibas-Itacarambi earthquake of December 09, 2007 (4.9 m(b)), Minas Gerais State, Brazil

On December 9, 2007, a 4.9 m(b) earthquake occurred in the middle of the Sao Francisco Craton, in a region with no known previous activity larger than 4 m(b). This event reached intensity VII MM (Modified Mercalli) causing the first fatal victim in Brazil. The activity had started in May 25, 2007 with a 3.5 magnitude event and continued for several months, motivating the deployment of a local 6-station network. A three week seismic quiescence was observed before the mainshock. Initial absolute hypocenters were calculated with best fitting velocity models and then relative locations were determined with hypoDD. The aftershock distribution indicates a 3 km long rupture for the mainshock. The fault plane solution, based on P-wave polarities and hypocentral trend, indicates a reverse faulting mechanism on a N30 degrees E striking plane dipping about 40 degrees to the SE. The rupture depth extends from about 0.3 to 1.2 km only. Despite the shallow depth of the mainshock, no surface feature could be correlated with the fault plane. Aeromagnetic data in the epicentral area show short-wavelength lineaments trending NNE-SSW to NE-SW which we interpret as faults and fractures in the craton basement beneath the surface limestone layer. We propose that the Caraibas-Itacarambi seismicity is probably associated with reactivation of these basement fractures and faults under the present E-W compressional stress field in this region of the South American Plate. (c) 2009 Elsevier B.V. All rights reserved.

Induced seismicity in the Castarthao reservoir, NE Brazil - Preliminary results

The Castanhao reservoir was built in the state of Ceara, a dry region in Northeastern Brazil, to regulate the flow of the Jaguaribe River, for irrigation, and for power generation. It is an earth-filled dam, 60 m high, with a water capacity of 4.5 x 10(9) m(3). The seismicity in the area has been monitored since 1998, with a few interruptions, using one analog or one digital station and, during a few periods, a three-station network. The first earthquakes likely to be induced events were detected in 2003, when the water level was about 20 in high. In early 2004 a very heavy rainfall season quickly filled the reservoir. Shortly after, an increase in the seismic activity occurred and many micro-earthquakes were recorded. We suggest that this activity resulted from an increase in pore pressure due to undrained response. Therefore, we may classify this cluster of microearthquakes as ""initial seismicity."" We deployed a network with four analog stations in the area, following this activity, to determine the epicentral zone. At least three epicentral areas under the reservoir were detected. The spatio-temporal analysis of the available data revealed that the seismicity occurs in clusters and that these were activated at different periods. We identified four sets of faults (N-S-, E-W-, NW-SE-, and NE-SW-oriented), some of which moved in shallow crustal levels and as recently as the Quaternary (1.8 Ma). Under the present-day stress regime, the last two sets moved as strike-slip structures. We suggest a possible correlation between dormant faults and the observed induced seismicity. (c) 2008 Elsevier B.V. All rights reserved.

Alveolar macrophages from susceptible mice are more competent than those of resistant mice to control initial Paracoccidioides brasiliensis infection

Alveolar macrophages ( AM) are the first host cells to interact with Paracoccidioides brasiliensis (Pb), a primary human pathogen that causes severe pulmonary infections in Latin America. To better understand innate immunity in pulmonary paracoccidioidomycosis, we decided to study the fungicidal and secretory abilities of AM from resistant (A/J) and susceptible (B10.A) mice to infection. Untreated, IFN-gamma and IL-12 primed AM from B10. A and A/J mice were challenged with P. brasiliensis yeasts and cocultured for 72 h. B10. A macrophages presented an efficient fungicidal ability, were easily activated by both cytokines, produced high levels of nitric oxide ( NO), IL-12, and MCP-1 associated with low amounts of IL-10 and GM-CSF. In contrast, A/J AM showed impaired cytokine activation and fungal killing, secreted high levels of IL- 10 and GM-CSF but low concentrations of NO, IL- 12, and MCP-1. The fungicidal ability of B10. A but not of A/J macrophages was diminished by aminoguanidine treatment, although only the neutralization of TGF-beta restored the fungicidal activity of A/J cells. This pattern of macrophage activation resulted in high expression of MHC class II antigens by A/J cells, while B10. A macrophages expressed elevated levels of CD40. Unexpectedly, our results demonstrated that susceptibility to a fungal pathogen can be associated with an efficient innate immunity, while a deficient innate response can ultimately favor the development of a resistant pattern to infection. Moreover, our data suggest that different pathogen recognition receptors are used by resistant and susceptible hosts to interact with P. brasiliensis yeasts, resulting in divergent antigen presentation, acquired immunity, and disease outcomes.

Anisotropy of thermal stresses in confined dusty plasmas

Anisotropy of thermal stresses in confined dusty plasmas is considered. It is shown that in a multi-component low-temperature plasma containing electrons, ions and dust, the complicated dependence of the ion viscosity on ion temperature gradients leads to a plasma equilibrium state with anisotropic pressure. This pressure anisotropy can be of the order of the ion pressure in some limiting cases, in which the ion Larmor radius or the ion mean free path are of the order of the characteristic length of the plasma nonuniformity. For a sufficiently large dust number density, they contribute to the plasma pressure anisotropy and to its spatial dependence. Currently, it is not yet clear whether this equilibrium state is stable or not. Under these conditions, some convective plasma flows can arise in confinement devices. Therefore, this question needs special consideration.

A closer look at the influence of tubular initial conditions on two-particle correlations

In a recent paper, the hydrodynamic code NEXSPheRIO was used in conjunction with STAR analysis methods to study two-particle correlations as a function of Delta(eta) and Delta phi. The various structures observed in the data were reproduced. In this work, we discuss the origin of these structures as well as present new results.

Hydrodynamics: Fluctuating initial conditions and two-particle correlations

Event-by-event hydrodynamics (or hydrodynamics with fluctuating initial conditions) has been developed in the past few years. Here we discuss how it may help to understand the various structures observed in two-particle correlations. (C) 2010 Elsevier B.V. All rights reserved.

Predictions from an anisotropic inflationary era

This paper investigates the predictions of an inflationary phase starting from a homogeneous and anisotropic universe of the Bianchi I type. After discussing the evolution of the background spacetime, focusing on the number of e-folds and the isotropization, we solve the perturbation equations and predict the power spectra of the curvature perturbations and gravity waves at the end of inflation. The main features of the early anisotropic phase is (1) a dependence of the spectra on the direction of the modes, (2) a coupling between curvature perturbations and gravity waves and (3) the fact that the two gravity wave polarizations do not share the same spectrum on large scales. All these effects are significant only on large scales and die out on small scales where isotropy is recovered. They depend on a characteristic scale that can, but a priori must not, be tuned to some observable scale. To fix the initial conditions, we propose a procedure that generalizes the one standardly used in inflation but that takes into account the fact that the WKB regime is violated at early times when the shear dominates. We stress that there exist modes that do not satisfy the WKB condition during the shear-dominated regime and for which the amplitude at the end of inflation depends on unknown initial conditions. On such scales, inflation loses its predictability. This study paves the way for the determination of the cosmological signature of a primordial shear, whatever the Bianchi I spacetime. It thus stresses the importance of the WKB regime to draw inflationary predictions and demonstrates that, when the number of e-folds is large enough, the predictions converge toward those of inflation in a Friedmann-Lemaitre spacetime but that they are less robust in the case of an inflationary era with a small number of e-folds.

PACKMOL: A Package for Building Initial Configurations for Molecular Dynamics Simulations

Adequate initial configurations for molecular dynamics simulations consist of arrangements of molecules distributed in space in such a way to approximately represent the system`s overall structure. In order that the simulations are not disrupted by large van der Waals repulsive interactions, atoms from different molecules Must keep safe pairwise distances. Obtaining Such a molecular arrangement can be considered it packing problem: Each type molecule must satisfy spatial constraints related to the geometry of the system, and the distance between atoms of different molecules Must be greater than some specified tolerance. We have developed a code able to pack millions of atoms. grouped in arbitrarily complex molecules, inside a variety of three-dimensional regions. The regions may be intersections of spheres, ellipses, cylinders, planes, or boxes. The user must provide only the structure of one molecule of each type and the geometrical constraints that each type of molecule must satisfy. Building complex mixtures, interfaces, solvating biomolecules in water, other solvents, or mixtures of solvents, is straight forward. In addition. different atoms belonging to the same molecule may also be restricted to different spatial regions, in Such a way that more ordered molecular arrangements call be built, as micelles. lipid double-layers, etc. The packing time for state-of-the-art molecular dynamics systems varies front a few seconds to a few Minutes in a personal Computer. The input files are simple and Currently compatible with PDB, Tinker, Molden, or Moldy coordinate files. The package is distributed as free software and call be downloaded front http://www.ime.unicamp.br/similar to martinez/packmol/. (C) 2009 Wiley Periodicals. Inc. J Comput Chem 30: 2157-2164, 2009

Generalized solutions of a nonlinear parabolic equation with generalized functions as initial data

In [H. Brezis, A. Friedman, Nonlinear parabolic equations involving measures as initial conditions, J. Math. Pure Appl. (9) (1983) 73-97.] Brezis and Friedman prove that certain nonlinear parabolic equations, with the delta-measure as initial data, have no solution. However in [J.F. Colombeau, M. Langlais, Generalized solutions of nonlinear parabolic equations with distributions as initial conditions, J. Math. Anal. Appl (1990) 186-196.] Colombeau and Langlais prove that these equations have a unique solution even if the delta-measure is substituted by any Colombeau generalized function of compact support. Here we generalize Colombeau and Langlais` result proving that we may take any generalized function as the initial data. Our approach relies on recent algebraic and topological developments of the theory of Colombeau generalized functions and results from [J. Aragona, Colombeau generalized functions on quasi-regular sets, Publ. Math. Debrecen (2006) 371-399.]. (C) 2009 Elsevier Ltd. All rights reserved.

Movements and mechanical stresses in gas-filled flat plate solar collectors

Sealed gas filled flat plate solar collectors will have stresses in the material since volume and pressure varies in the gas when the temperature changes. Several geometries were analyzed and it could be seen that it is possible reducing the stresses and improve the safety factor of the weakest point in the construction by using larger area and/or reducing the distance between glass and absorber and/or change width and height relationship so the tubes are getting longer. Further it could be shown that the safety factor won't always get improved with reinforcements. It is so because when an already strong part of the collector gets reinforced it will expose weaker parts for higher stresses. The finite element method was used for finding out the stresses.

How initial vocational education and training (IVET) teachers in Sweden perceive their prospects of being able to prepare upper secondary school pupils for a future occupation

Vocational teachers in Swedish upper secondary schools are a heterogeneous category of teachers, connected to different types of trade. These teachers represent a broad set of trade skills varying in content and character. In their teacher role, they continue to wear the clothes, speak the language, share the culture and remain mentally in their former professions. Still, it is central that they keep up this contact to be able to school the pupils into the environment of the trade in question, but also to help them to understand what skills a profession demands. However, the individual teacher also has to distance himself from the negative elements in the culture of the profession: patterns and habits that, for various reasons, have to be broken or changed. This paper draws attention to the ways in which a group of vocational teachers, who were participants in a project that aimed to train unauthorized vocational teachers, expressed their ambitions to prepare the pupils for a future professional career. When collecting information, we used the degree dissertations they produced and discussed in seminars, and informal dialogues. The result shows that it is important that the instruction location resembles a real working site as far as possible. These places are more or less realistic copies of a garage, a restaurant kitchen, a hairdressing salon, and so on, in order to give the pupils a realistic setting for instruction. However, the fact that these simulated workplaces lack the necessary support functions that exist in a company creates problems, problems which make a lot of extra work for the teachers. Vocational teachers also have to instruct the pupil in the experienced practitioner’s professional skills and working situation, but the pupil herself/himself must learn the job by doing it in practice. Some vocational upper secondary programs lack relevant course literature and the businesses give little support. This also makes extra work for the teachers. Moreover, the distance between the vocational programs and the trainee jobs was experienced as being difficult to overcome. One reason seems to be differences between businesses and differing preconditions between small and big companies’ abilities to take care of these pupils. The upper secondary school vocational programs also play a role in cementing existing gender roles, as well as perpetuating class-related patterns on the labour market.

How initial vocational education and training (IVET) teachers in Sweden perceive their prospects of being able to prepare upper secondary school pupils for a future occupation

Vocational teachers in Swedish upper secondary schools are a heterogeneous category of teachers, connected to different types of trade. These teachers represent a broad set of trade skills varying in content and character. In their teacher role, they continue to wear the clothes, speak the language, share the culture and remain mentally in their former professions. Still, it is central that they keep up this contact to be able to school the pupils into the environment of the trade in question, but also to help them to understand what skills a profession demands. However, the individual teacher also has to distance himself from the negative elements in the culture of the profession: patterns and habits that, for various reasons, have to be broken or changed. This paper draws attention to the ways in which a group of vocational teachers, who were participants in a project that aimed to train unauthorized vocational teachers, expressed their ambitions to prepare the pupils for a future professional career. When collecting information, we used the degree dissertations they produced and discussed in seminars, and informal dialogues. The result shows that it is important that the instruction location resembles a real working site as far as possible. These places are more or less realistic copies of a garage, a restaurant kitchen, a hairdressing salon, and so on, in order to give the pupils a realistic setting for instruction. However, the fact that these simulated workplaces lack the necessary support functions that exist in a company creates problems, problems which make a lot of extra work for the teachers. Vocational teachers also have to instruct the pupil in the experienced practitioner’s professional skills and working situation, but the pupil herself/himself must learn the job by doing it in practice. Some vocational upper secondary programs lack relevant course literature and the businesses give little support. This also makes extra work for the teachers. Moreover, the distance between the vocational programs and the trainee jobs was experienced as being difficult to overcome. One reason seems to be differences between businesses and differing preconditions between small and big companies’ abilities to take care of these pupils. The upper secondary school vocational programs also play a role in cementing existing gender roles, as well as perpetuating class-related patterns on the labour market.