Pachymetry-Guided Intrastromal Air Injection ("Pachy-Bubble") for Deep Anterior Lamellar Keratoplasty

To evaluate an innovative technique for intrastromal air injection to achieve deep anterior lamellar keratoplasty (DALK) with bare Descemet membrane (DM). Thirty-four eyes with anterior corneal pathology, including 27 with keratoconus, underwent DALK. After 400 mm trephination with a suction trephine, ultrasound pachymetry was performed 0.8 mm internally from the trephination groove in the 11 to 1 o'clock position. In this area, a 2-mm incision was created, parallel to the groove, with a micrometer diamond knife calibrated to 90% depth of the thinnest measurement. A cannula was inserted through the incision and 0.5 mL of air was injected to dissect the DM from the stroma. After peripheral paracentesis, anterior keratectomy was carried out to bare the DM. A 0.25-mm oversized graft was sutured in place. Overall, 94.1% of eyes achieved DALK. Bare DM was achieved in 30 eyes, and a pre-DM dissection was performed in 2 eyes. Air injection was successful in detaching the DM (achieving the big bubble) in 88.2% of the eyes. In keratoconus eyes, the rate was 88.9%. All cases but one required a single air injection to achieve DM detachment. Microperforations occurred in 5 cases: 3 during manual layer-by-layer dissection after air injection failed to detach the DM, 1 during removal of the residual stroma after big-bubble formation, and 1 during the diamond knife incision. Two cases (5.9%) were converted to penetrating keratoplasty because of macroperforations. The technique was reproducible, safe, and highly effective in promoting DALK with bare DM.

Firm Market Performance and Volatility in a National Real Estate Sector

We present empirical evidence using daily data for stock prices for 17 real estate companies traded in the Sao Paulo, Brazil stock exchange. from August 26, 2006 to March 31, 2010. We use the U.S. house price bubble, financial crisis and risk measures to instrument for momentums and reversals in the domestic real estate sector. We find evidence of conditional premium persistence and conditional volatility persistence in the market. We find that the conditional risk-return relationship in the sector is consistent with the prospect theory of risk attitudes in this period. Certain companies seem to be operating on a perceived potential industry return above the target, while most others are below the target, and the whole sector is below target on average. (C) 2011 Elsevier Inc. All rights reserved.

Constraining H-0 in general dark energy models from Sunyaev-Zeldovich/X-ray technique and complementary probes

In accelerating dark energy models, the estimates of the Hubble constant, Ho, from Sunyaev-Zerdovich effect (SZE) and X-ray surface brightness of galaxy clusters may depend on the matter content (Omega(M)), the curvature (Omega(K)) and the equation of state parameter GO. In this article, by using a sample of 25 angular diameter distances of galaxy clusters described by the elliptical beta model obtained through the SZE/X-ray technique, we constrain Ho in the framework of a general ACDM model (arbitrary curvature) and a flat XCDM model with a constant equation of state parameter omega = p(x)/rho(x). In order to avoid the use of priors in the cosmological parameters, we apply a joint analysis involving the baryon acoustic oscillations (BA()) and the (MB Shift Parameter signature. By taking into account the statistical and systematic errors of the SZE/X-ray technique we obtain for nonflat ACDM model H-0 = 74(-4.0)(+5.0) km s(-1) Mpc(-1) (1 sigma) whereas for a fiat universe with constant equation of state parameter we find H-0 = 72(-4.0)(+5.5) km s(-1) Mpc(-1)(1 sigma). By assuming that galaxy clusters are described by a spherical beta model these results change to H-0 = 6(-7.0)(+8.0) and H-0 = 59(-6.0)(+9.0) km s(-1) Mpc(-1)(1 sigma), respectively. The results from elliptical description are in good agreement with independent studies from the Hubble Space Telescope key project and recent estimates based on the Wilkinson Microwave Anisotropy Probe, thereby suggesting that the combination of these three independent phenomena provides an interesting method to constrain the Bubble constant. As an extra bonus, the adoption of the elliptical description is revealed to be a quite realistic assumption. Finally, by comparing these results with a recent determination for a, flat ACDM model using only the SZE/X-ray technique and BAO, we see that the geometry has a very weak influence on H-0 estimates for this combination of data.

Period adding cascades: Experiment and modeling in air bubbling

Period adding cascades have been observed experimentally/numerically in the dynamics of neurons and pancreatic cells, lasers, electric circuits, chemical reactions, oceanic internal waves, and also in air bubbling. We show that the period adding cascades appearing in bubbling from a nozzle submerged in a viscous liquid can be reproduced by a simple model, based on some hydrodynamical principles, dealing with the time evolution of two variables, bubble position and pressure of the air chamber, through a system of differential equations with a rule of detachment based on force balance. The model further reduces to an iterating one-dimensional map giving the pressures at the detachments, where time between bubbles come out as an observable of the dynamics. The model has not only good agreement with experimental data, but is also able to predict the influence of the main parameters involved, like the length of the hose connecting the air supplier with the needle, the needle radius and the needle length. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3695345]

Use of Chlorine to Remove Magnesium from Molten Aluminum

Removal of Mg from aluminum scraps, known as demagging, has been widely applied in the,aluminum industry. This work discusses bubble-formation theories and magnesium kinetic removal from aluminum scraps using chlorine and inert gas fluxing. The interfacial area of the bubbles and residence time were estimated using a mathematical model. To inject gaseous chlorine, three types of nozzles were used with varying internal diameter. In addition, a porous plug, as well as varying input chlorine flow and concentration were used. The use of lower chlorine concentration improves efficiency because the interfacial tension is reduced therefore, more and smaller bubbles are formed. The model proposed herein is consistent with the experimental data. [doi:10.2320/matertrans.M2011256]

Parâmetros de dispersão de ar em células mecânicas de flotação em usinas brasileiras

O objetivo desse trabalho é apresentar e discutir a determinação dos parâmetros de dispersão de ar em células mecânicas de flotação, em circuitos industriais brasileiros. Foram investigados os circuitos rougher e scavenger das usinas RPM, Taquari-Vassouras, Copebras e Fosfértil-Catalão (atual Vale Fertilizantes). Nas usinas RPM e Taquari-Vassouras, foram determinados a velocidade superficial do ar (Jg), o hold-up do ar (εg), o diâmetro médio de bolhas (d32) e o fluxo de área superficial de bolhas (Sb). Para as outras usinas, foram determinados somente o Jg e εg. Os resultados mostraram que, com exceção da RPM, todos os circuitos investigados apresentaram baixos valores para os parâmetros de dispersão do ar. Taquari-Vassouras apresentou os mais baixos valores médios para Jg e εg, respectivamente, 0,05 cm/s e 5%. Os maiores valores de Jg foram determinados no circuito rougher da Copebras, 1,17 cm/s, ao passo que a RPM apresentou os maiores valores para o hold-up e tamanho de bolha, respectivamente, 31% e 2,61mm. Os valores obtidos, para Sb, situaram-se abaixo daqueles reportados na literatura.

THE INTERSTELLAR MAGNETIC FIELD CLOSE TO THE SUN. II.

The magnetic field in the local interstellar medium (ISM) provides a key indicator of the galactic environment of the Sun and influences the shape of the heliosphere. We have studied the interstellar magnetic field (ISMF) in the solar vicinity using polarized starlight for stars within 40 pc of the Sun and 90 degrees of the heliosphere nose. In Frisch et al. (Paper I), we developed a method for determining the local ISMF direction by finding the best match to a group of interstellar polarization position angles obtained toward nearby stars, based on the assumption that the polarization is parallel to the ISMF. In this paper, we extend the analysis by utilizing weighted fits to the position angles and by including new observations acquired for this study. We find that the local ISMF is pointed toward the galactic coordinates l, b = 47 degrees +/- 20 degrees, 25 degrees +/- 20 degrees. This direction is close to the direction of the ISMF that shapes the heliosphere, l, b = 33 degrees +/- 4 degrees, 55 degrees +/- 4 degrees, as traced by the center of the "Ribbon" of energetic neutral atoms discovered by the Interstellar Boundary Explorer (IBEX) mission. Both the magnetic field direction and the kinematics of the local ISM are consistent with a scenario where the local ISM is a fragment of the Loop I superbubble. A nearby ordered component of the local ISMF has been identified in the region l approximate to 0 degrees -> 80 degrees and b approximate to 0 degrees -> 30 degrees, where PlanetPol data show a distance-dependent increase of polarization strength. The ordered component extends to within 8 pc of the Sun and implies a weak curvature in the nearby ISMF of +/- 0 degrees.25 pc(-1). This conclusion is conditioned on the small sample of stars available for defining this rotation. Variations from the ordered component suggest a turbulent component of +/- 23 degrees. The ordered component and standard relations between polarization, color excess, and H-o column density predict a reasonable increase of N(H) with distance in the local ISM. The similarity of the ISMF directions traced by the polarizations, the IBEX Ribbon, and pulsars inside the Local Bubble in the third galactic quadrant suggest that the ISMF is relatively uniform over spatial scales of 8-200 pc and is more similar to interarm than spiral-arm magnetic fields. The ISMF direction from the polarization data is also consistent with small-scale spatial asymmetries detected in GeV-TeV cosmic rays with a galactic origin. The peculiar geometrical relation found earlier between the cosmic microwave background dipole moment, the heliosphere nose, and the ISMF direction is supported by this study. The interstellar radiation field at +/- 975 angstrom does not appear to play a role in grain alignment for the low-density ISM studied here.

Experimental investigation of gravitational gas separation in an inclined annular channel

The oil industry uses gas separators in production wells as the free gas present in the suction of the pump reduces the pumping efficiency and pump lifetime. Therefore, free gas is one of the most important variables in the design of pumping systems. However, in the literature there is little information on these separators. It is the case of the inverted-shroud gravitational gas separator. It has an annular geometry due to the installation of a cylindrical container in between the well casing and pioduction pipe (tubing). The purpose of the present study is to understand the phenomenology and behavior of inverted-shroud separator. Experimental tests were performed in a 10.5-m-length inclinable glass tube with air and water as working fluids. The water flow rate was in the range of 8.265-26.117 l/min and the average inlet air mass flow rate was 1.1041 kg/h, with inclination angles of 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 80 degrees and 85 degrees. One of the findings is that the length between the inner annular level and production pipe inlet is one of the most important design parameters and based on that a new criterion for total gas separation is proposed. We also found that the phenomenology of the studied separator is not directly dependent on the gas flow rate, but on the average velocity of the free surface flow generated inside the separator. Maps of efficiency of gas separation were plotted and showed that liquid flow rate, inclination angle and pressure difference between casing and production pipe outlet are the main variables related to the gas separation phenomenon. The new data can be used for the development of design tools aiming to the optimized project of the pumping system for oil production in directional wells. (C) 2012 Elsevier Inc. All rights reserved.

Ajuste e balanceamento do portfólio de projetos: o caso de uma empresa do setor químico

O objetivo deste trabalho é compreender a etapa de ajuste no contexto da gestão do portfólio de projetos, destacando sua relação com os processos de categorização e balanceamento. A pesquisa realizada tem caráter qualitativo, sendo a abordagem adotada o estudo de caso longitudinal. A pesquisa foi desenvolvida em uma empresa do setor químico brasileiro. As evidências, de várias fontes, foram coletadas através de entrevistas, documentos e dados dos sistemas corporativos. Para a compreensão do portfólio de projetos da empresa foram coletados e analisados dados de mil projetos realizados entre 2001 e 2005. Os resultados indicam que maior atenção é dada à etapa de seleção, negligenciando a etapa de ajuste. A adoção de ferramentas de balanceamento permitiu evidenciar lacunas e fontes de desbalanceamento no portfólio de projetos, promovendo o debate entre os tomadores de decisão no que concerne ao viés introduzido pelos critérios adotados na etapa de seleção e levantando a necessidade de introdução de uma sistemática de ajuste e balanceamento. Observou-se que sem uma adequada categorização dos projetos da empresa seria difícil promover a análise de balanceamento.

Usable work of macro-scale cavities in liquids

It is shown that the generation of cavities in a liquid can produce usable work, which is illustrated by the stretching of a string. This work is done during the expansion of the cavity, and not with its collapse. Basic equations are presented for the movement of a device moved by the so called cavity events. A theoretical solution is also proposed, which uses polynomial functions relating the so called "excess of pressure" in the cavity and time. Evaluations of the force generated during the expansion of the cavity showed a mean peak value of about 58 N for the moving container, while measurements with the container fixed to a support showed a peak value of 476 N, considered somewhat overestimated, because high frequency oscillations seem to superpose the mean behavior. Simultaneous phenomena occurring during the cavity events are also described. Series of pictures of the experiments are presented.