WorldWideScience

Sample records for neurological effects bubble

  1. Effect of bubble deformability on the vertical channel bubbly flow

    OpenAIRE

    Dabiri, Sadegh; Lu, Jiacai; Tryggvason, Gretar

    2012-01-01

    This article describes the fluid dynamics video: "Effect of bubble deformability on the vertical channel bubbly flow". The effect of bubble deformability on the flow rate of bubbly upflow in a turbulent vertical channel is examined using direct numerical simulations. A series of simulations with bubbles of decreasing deformability reveals a sharp transition from a flow with deformable bubbles uniformly distributed in the middle of the channel to a flow with nearly spherical bubbles with a wal...

  2. Bernoulli Suction Effect on Soap Bubble Blowing?

    Science.gov (United States)

    Davidson, John; Ryu, Sangjin

    2015-11-01

    As a model system for thin-film bubble with two gas-liquid interfaces, we experimentally investigated the pinch-off of soap bubble blowing. Using the lab-built bubble blower and high-speed videography, we have found that the scaling law exponent of soap bubble pinch-off is 2/3, which is similar to that of soap film bridge. Because air flowed through the decreasing neck of soap film tube, we studied possible Bernoulli suction effect on soap bubble pinch-off by evaluating the Reynolds number of airflow. Image processing was utilized to calculate approximate volume of growing soap film tube and the volume flow rate of the airflow, and the Reynolds number was estimated to be 800-3200. This result suggests that soap bubbling may involve the Bernoulli suction effect.

  3. Bubbles

    DEFF Research Database (Denmark)

    Dholakia, Nikhilesh; Turcan, Romeo V.

    2013-01-01

    A goal of our ongoing research stream is to develop a multidisciplinary metatheory of bubbles. In this viewpoint paper we put forward a typology of bubbles by comparing four types of assets – entertainment, commodities, financial securities (stocks), and housing properties – where bubbles could a...

  4. Effect of bubble's arrangement on the viscous torque in bubbly Taylor-Couette flow

    Science.gov (United States)

    Fokoua, G. Ndongo; Gabillet, C.; Aubert, A.; Colin, C.

    2015-03-01

    An experimental investigation of the interactions between bubbles, coherent motion, and viscous drag in a Taylor-Couette flow with the outer cylinder at rest is presented. The cylinder radii ratio η is 0.91. Bubbles are injected inside the gap through a needle at the bottom of the apparatus. Different bubbles sizes are investigated (ratio between the bubble diameter and the gap width ranges from 0.05 to 0.125) for very small void fraction (α ≤ 0.23%). Different flow regimes are studied corresponding to Reynolds number Re based on the gap width and velocity of the inner cylinder, ranging from 6 × 102 to 2 × 104. Regarding these Re values, Taylor vortices are persistent leading to an axial periodicity of the flow. A detailed characterization of the vortices is performed for the single-phase flow. The experiment also develops bubbles tracking in a meridian plane and viscous torque of the inner cylinder measurements. The findings of this study show evidence of the link between bubbles localisation, Taylor vortices, and viscous torque modifications. We also highlight two regimes of viscous torque modification and various types of bubbles arrangements, depending on their size and on the Reynolds number. Bubbles can have a sliding and wavering motion near the inner cylinder and be either captured by the Taylor vortices or by the outflow areas near the inner cylinder. For small buoyancy effect, bubbles are trapped, leading to an increase of the viscous torque. When buoyancy induced bubbles motion is increased by comparison to the coherent motion of the liquid, a decrease in the viscous torque is rather observed. The type of bubble arrangement is parameterized by the two dimensionless parameters C and H introduced by Climent et al. ["Preferential accumulation of bubbles in Couette-Taylor flow patterns," Phys. Fluids 19, 083301 (2007)]. Phase diagrams summarizing the various types of bubbles arrangements, viscous torque modifications, and axial wavelength evolution are

  5. A note on effects of rational bubble on portfolios

    Science.gov (United States)

    Wang, Chan; Nie, Pu-yan

    2018-02-01

    In general, demand increases in wealth and decreases in price in microeconomics. We thereby propose a completely different perspective. By establishing expected utility function of investors, this article introduces one rational bubble asset and one bubble free asset in portfolios and focuses on the effects of bubble on investment portfolios from wealth and price perspectives. All conclusions are obtained by theoretical analysis with microeconomics theory. We argue that inferior goods and Giffen behavior can occur for the bubble free asset in microeconomic fields. The results can help investors to recognize bubble assets and bubble free assets more scientifically. Both bubble and bubble free assets can be inferior goods under some conditions, so we cannot to say which asset better than the other one absolutely.

  6. Effect of surfactant on the evolution of bubble motion

    Directory of Open Access Journals (Sweden)

    Antonnikova Aleksandra

    2017-01-01

    Full Text Available Results of an experimental study of the process of ascent of a single bubble of air in the presence of a surfactant are presented. An empirical dependence for drag coefficient of the bubble that emerges in a liquid containing a surfactant in the region of small Reynolds numbers has been obtained. Theoretical studies of the effect of surfactants on the velocity of motion of a bubble in a nonstationary regime have been carried out. A theoretical analysis of the effect of nonstationary forces on the dynamics of bubble rising in the nonstationary regime has been conducted.

  7. Effect of Bulk and Interfacial Rheological Properties on Bubble Dissolution

    NARCIS (Netherlands)

    Kloek, W.; Vliet, van T.; Meinders, M.

    2001-01-01

    This paper describes theoretical calculations of the combined effect of bulk and interracial rheological properties on dissolution behavior of a bubble in an infinite medium at saturated conditions. Either bulk or interracial elasticity can stop the bubble dissolution process, and stability criteria

  8. The effect of coupling on bubble fragmentation acoustics.

    Science.gov (United States)

    Czerski, Helen; Deane, Grant B

    2011-01-01

    Understanding the formation and evolution of bubble populations is important in a wide range of situations, including industrial processes, medical applications, and ocean science. Passive acoustical techniques can be used to track changes in the population, since each bubble formation or fragmentation event is likely to produce sound. This sound potentially contains a wealth of information about the fragmentation process and the products, but to fully exploit these data it is necessary to understand the physical processes that determine its characteristics. The focus of this paper is binary fragmentation, when turbulence causes one bubble to split into two. Specifically, the effect that bubble-bubble coupling has on the sound produced is examined. A numerical simulation of the acoustical excitation of fragmenting bubbles is used to generate model acoustic signals, which are compared with experimental data. A frequency range with a suppressed acoustic output which is observed in the experimental data can be explained when coupling is taken into account. In addition, although the driving mechanism of neck collapse is always consistent with the data for the larger bubble of the newly formed pair, a different mechanism must be driving the smaller bubble in some situations.

  9. Effect of surfactant on the evolution of bubble motion

    OpenAIRE

    Antonnikova Aleksandra; Usanina Anna

    2017-01-01

    Results of an experimental study of the process of ascent of a single bubble of air in the presence of a surfactant are presented. An empirical dependence for drag coefficient of the bubble that emerges in a liquid containing a surfactant in the region of small Reynolds numbers has been obtained. Theoretical studies of the effect of surfactants on the velocity of motion of a bubble in a nonstationary regime have been carried out. A theoretical analysis of the effect of nonstationary forces on...

  10. [Air bubble effect during alloy cooling in shielding blocks radiotherapy].

    Science.gov (United States)

    Ostinelli, A; Gelosa, S; Frigerio, M; Monti, A F

    1998-10-01

    Shaped fields are widely used in radiotherapy to protect critical organs and to avoid unnecessary normal tissue irradiation. The most common system for photon beam shaping consists in a low melting point alloy. We studied the air bubbles which can occur during alloy cooling with both new and remelted alloys and when different cooling techniques are chosen. Forty cone samples (18 of remelted alloy and 22 of new alloy) were prepared to evaluate the frequence of air bubble recurrence, with reproducible geometric sizes (height = 70 mm, major base surface diameter = 60 mm, minor base surface diameter = 40 mm). Air bubble sizes and dose inhomogeneity were evaluated by reproducing 60Co radiograph of each sample (two orthogonal projections: 6 x 7 cm). The samples were cooled at a constant temperature, following three different modalities: high (25 degrees C), medium (5 degrees C), low (-20 degrees C) temperature. Owing to the small geometrical magnification, air bubble sizes were determined by measuring their surface on samples lateral projections, taking into account the sight detectable bubble edges. Up to 300 mm2 lateral surface bubbles are always present in all castings. Casting inhomogeneities can produce a film-density inhomogeneity ranging from 9% to 40%. The spatial distribution of bubbles seems to be random. Bubble recurrence is independent of both the metal alloy (repeatedly used castings) and the different block cooling modalities. The effect of air bubbles on the shielded areas dose inhomogeneity is generally of no relevant importance. However, these inhomogeneities can produce hot spots which must be taken into accurate consideration only in the particular treatments where critical small size organ dose sparing represents a basic issue (i.e. the shielding of eye lens).

  11. Effective Compressibility of a Bubbly Slurry: I. Theory of the Behavior of Bubbles Trapped in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Kam, Seung I.(PEMEX REFINACION); Gauglitz, Phillip A.(BATTELLE (PACIFIC NW LAB)); Rossen, William R.(UNKNOWN)

    2000-12-01

    Bubbles trapped within the slurry at the bottom of waste tanks at the Hanford Site expand and contract in response to ambient pressure changes. These bubbles contain hydrogen and other flammable gases that can pose a safety hazard. Determining the effective compressibility of bubbles in the slurry could allow one to make improved estimates of the quantity of gas trapped in the slurry from changes in slurry volume with ambient pressure changes. Numerical calculations based on a one-dimensional biconical-pore-network model show that the effective compressibility of a population of bubbles shows hysteresis with pressure increase and decrease. This hysteresis is caused by the unsteady, impulsive movements of interfaces from pore throat to throat during a pressure decrease and from pore body to body during a pressure increase. Snap-off may occur during these jumps but does not significantly alter the effective compressibility of the population of bubbles.

  12. Effective Compressibility of a Bubbly Slurry.

    Science.gov (United States)

    Kam, S. I.; Gauglitz, P. A.; Rossen, W. R.

    2001-09-01

    The goal of this study is to fit model parameters to changes in waste level in response to barometric pressure changes in underground storage tanks at the Hanford Site. This waste compressibility is a measure of the quantity of gas, typically hydrogen and other flammable gases, that can pose a safety hazard, retained in the waste. A one-dimensional biconical-pore-network model for compressibility of a bubbly slurry is presented in a companion paper. Fitting these results to actual waste level changes in the tanks implies that bubbles in the slurry layer are long and the ratio of pore-body radius to pore-throat radius is close to 1; unfortunately, compressibility can not be quantified unambiguously from the data without additional information on pore geometry. Therefore, determining the quantity of gas in the tanks requires more than just waste-level data. The non-uniqueness of the fit is also found with two other simple models: a capillary-tube model with contact angle hysteresis and a spherical-pore model. Copyright 2001 Academic Press.

  13. Dynamic pitching effect on a laminar separation bubble

    NARCIS (Netherlands)

    Nati, A.; De Kat, R.; Scarano, F.; Van Oudheusden, B.W.

    2015-01-01

    The unsteady effect of a periodic pitching motion on the characteristic of a laminar separation bubble on the suction side of a SD7003 aerofoil is investigated by means of time-resolved planar and tomographic particle image velocimetry. The measurements provide information on the separation,

  14. Bubble coalescence

    NARCIS (Netherlands)

    Orvalho, Sandra; Ruzicka, Marek C.; Olivieri, Giuseppe; Marzocchella, Antonio

    2015-01-01

    The goal of this study is to present new experimental data on the effect of the bubble approach velocity and liquid viscosity on pairwise bubble coalescence. Measurements were performed to investigate the dynamics of bubble coalescence under well-defined laboratory conditions. Air and pure

  15. Effects of mass transfer on damping mechanisms of vapor bubbles oscillating in liquids.

    Science.gov (United States)

    Zhang, Yuning; Gao, Yuhang; Guo, Zhongyu; Du, Xiaoze

    2018-01-01

    The damping mechanisms play an important role in the behavior of vapor bubbles. In the present paper, effects of mass transfer on the damping mechanisms of oscillating vapor bubbles in liquids are investigated within a wide range of parameter zone (e.g. in terms of frequency and bubble Péclet number). Results of the vapor bubbles are also compared with those of the gas bubbles. Our findings reveal that the damping mechanisms of vapor bubbles are significantly affected by the mass transfer especially in the regions with small and medium bubble Péclet number. Comparing with the gas bubbles, the contributions of the mass-transfer damping mechanism for the vapor bubble case are quite significant, being the dominant damping mechanism in a wide region. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Effects of surfactant on bubble hydrodynamic behavior under flotation-related conditions in wastewater.

    Science.gov (United States)

    Li, Yanpeng; Zhu, Tingting; Liu, Yanyan; Tian, Ye; Wang, Huanran

    2012-01-01

    Bubble behavior is fundamental to the performance of froth flotation operations used in wastewater treatment processes. To fully understand and characterize bubble behavior under flotation-related conditions in wastewater, the high-speed photographic method has been employed to examine the motion of single bubbles and size distribution of bubble swarms with intermediate sizes ranging from 1 to 4 mm in the presence of surfactants in a laboratory scale flotation column. Both distilled water and synthetic municipal wastewater have been used to make solutions as well as two types of common surfactants. The instantaneous bubble motion has been recorded by a high speed camera. Subsequently, bubble trajectory, dimensions, velocity and distribution have been determined from the recorded frames using the image analysis software. The experimental results show that the addition of surfactant into wastewater has similar effects on bubble hydrodynamic behavior as in pure water (e.g., improving trajectory stabilization, dampening bubble deformation, slowing down terminal velocity, reducing bubble size and increasing the specific surface area of bubble swarm) due to the Marangoni effect. However, it is interesting to note that surfactant effects on single bubble hydrodynamics in wastewater are slightly stronger than those in pure water while surfactant effects on size parameters of bubble swarms in wastewater are significantly stronger than those in pure water. This finding suggests that besides surfactant, inorganic salts present in synthetic wastewater have an important influence on bubble dispersion.

  17. Short term effect of hubble-bubble smoking on voice.

    Science.gov (United States)

    Hamdan, A-L; Sibai, A; Mahfoud, L; Oubari, D; Ashkar, J; Fuleihan, N

    2011-05-01

    To investigate the short term effect of hubble-bubble smoking on voice. Prospective study. Eighteen non-dysphonic subjects (seven men and 11 women) with a history of hubble-bubble smoking and no history of cigarette smoking underwent acoustic analysis and laryngeal video-stroboscopic examination before and 30 minutes after hubble-bubble smoking. On laryngeal video-stroboscopy, none of the subjects had vocal fold erythema either before or after smoking. Five patients had mild vocal fold oedema both before and after smoking. After smoking, there was a slight increase in the number of subjects with thick mucus between the vocal folds (six, vs four before smoking) and with vocal fold vessel dilation (two, vs one before smoking). Acoustic analysis indicated a drop in habitual pitch, fundamental frequency and voice turbulence index after smoking, and an increase in noise-to-harmonics ratio. Even 30 minutes of hubble-bubble smoking can cause a drop in vocal pitch and an increase in laryngeal secretions and vocal fold vasodilation.

  18. Bubble Departure from Metal-Graphite Composite Surfaces and Its Effects on Pool Boiling Heat Transfer

    Science.gov (United States)

    Chao, David F.; Sankovic, John M.; Motil, Brian J.; Yang, W-J.; Zhang, Nengli

    2010-01-01

    The formation and growth processes of a bubble in the vicinity of graphite micro-fiber tips on metal-graphite composite boiling surfaces and their effects on boiling behavior are investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the metal matrix in pool boiling. By virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the micro bubbles are sucked by the tips and merged into larger micro bubbles sitting on the end of the tips. The micro bubbles grow rapidly and coalesce to form macro bubbles, each spanning several tips. The necking process of a detaching macro bubble is analyzed. It is revealed that a liquid jet is produced by sudden break-off of the bubble throat. The composite surfaces not only have higher temperatures in micro- and macrolayers but also make higher frequency of the bubble departure, which increase the average heat fluxes in both the bubble growth stage and in the bubble departure period. Based on these analyses, the enhancement mechanism of pool boiling heat transfer on composite surfaces is clearly revealed.

  19. Warm Pressurant Gas Effects on the Liquid Hydrogen Bubble Point

    Science.gov (United States)

    Hartwig, Jason W.; McQuillen, John B.; Chato, David J.

    2013-01-01

    This paper presents experimental results for the liquid hydrogen bubble point tests using warm pressurant gases conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine mesh screen samples (325 x 2300, 450 x 2750, 510 x 3600) were tested in liquid hydrogen using cold and warm noncondensible (gaseous helium) and condensable (gaseous hydrogen) pressurization schemes. Gases were conditioned from 0 to 90 K above the liquid temperature. Results clearly indicate a degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensible pressurization. Degradation in the bubble point pressure is inversely proportional to screen porosity, as the coarsest mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.

  20. The effect of surface-active solutes on bubble coalescence in the presence of ultrasound.

    Science.gov (United States)

    Lee, Judy; Kentish, Sandra E; Ashokkumar, Muthupandian

    2005-03-24

    The sonication of an aqueous solution generates cavitation bubbles, which may coalesce and produce larger bubbles. This paper examines the effect of surface-active solutes on such bubble coalescence in an ultrasonic field. A novel capillary system has been designed to measure the change in the total volume resulting from the sonication of aqueous solutions with 515 kHz ultrasound pulses. This volume change reflects the total volume of larger gas bubbles generated by the coalescence of cavitation bubbles during the sonication process. The total volume of bubbles generated is reduced when surface-active solutes are present. We have proposed that this decrease in the total bubble volume results from the inhibition of bubble coalescence brought about by the surface-active solutes. The observed results revealed similarities with bubble coalescence data reported in the literature in the absence of ultrasound. It was found that for uncharged and zwitterionic surface-active solutes, the extent of bubble coalescence is affected by the surface activity of the solutes. The addition of 0.1 M NaCl to such solutes had no effect on the extent of bubble coalescence. Conversely, for charged surface-active solutes, the extent of bubble coalescence appears to be dominated by electrostatic effects. The addition of 0.1 M NaCl to charged surfactant solutions was observed to increase the total bubble volume close to that of the zwitterionic surfactant. This suggests the involvement of electrostatic interactions between cavitation bubbles in the presence of charged surfactants in the solution.

  1. The effects of neurologic assessment E-learning in nurses.

    Science.gov (United States)

    Shin, Ji Yeon; Issenberg, S Barry; Roh, Young Sook

    2017-10-01

    A firm understanding of the preliminary assessment of a patient with neurological disorders is needed for ensuring optimal patient outcomes. The purpose of this study is to evaluate the effects of using e-learning on neurologic assessment knowledge, ability, and self-confidence among nurses. This study used a non-equivalent control group pretest-posttest design. Nurses working in the neurology and neurosurgery wards, Republic of Korea PARTICIPANTS: A convenience sample of 50 nurses was assigned to either the experimental group (n=24) or the control group (n=26). The experimental group participated in the self-directed e-learning program related to neurologic assessment, and control group underwent self-directed learning with handout. Knowledge, ability, and self-confidence were measured at pretest and posttest. There were no significant differences in knowledge (U=270, p=0.399) and self-confidence (U=241.5, p=0.171) between the two groups. Nurses in the experimental group showed higher neurologic assessment ability compared with those in the control group (U=199, p=0.028). Self-directed neurologic assessment e-learning induced improvement in the neurologic assessment ability among nurses. Self-directed e-learning can be applied for improving competencies in neurologic assessment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Interaction of two cavitation bubbles in a tube and its effects on heat transfer

    Science.gov (United States)

    Liu, Bin; Cai, Jun; Tao, Yuequn; Huai, Xiulan

    2017-02-01

    When two cavitation bubbles exist in a confined space, the interaction between the bubbles significantly affects the characteristics of bubble dynamic behaviors. In this paper, a three-dimensional (3D) model is established to study the growth and collapse of two cavitation bubbles in a heated tube and its effects on heat transfer. The liquid and gas phases throughout the calculation domain are solved by a set of Navier-Stokes equations. It is assumed that the gas inside the bubble is compressible vapor, and the surrounding liquid is incompressible water. The mass transfer between two phases is ignored. The calculated bubble profiles were compared to the available experimental data, and a good agreement has been achieved. Then, the relationship among the bubble motion, flow field and pressure distributions was analyzed. On this basis, the effects of bubble interaction on the heat transfer between the wall surface and sounding liquid were discussed. It is found that heat transfer in the centre wall region is enhanced owing to the vortex flow and micro-jet induced by the bubble contraction and collapse. In contrast, the highest surface temperature appears in the surrounding region, which is mainly attributed to the thermal resistance induced by the bubble. The present study is helpful to understand the heat transfer phenomenon with cavitation in the liquid.

  3. Effect of static pressure on acoustic energy radiated by cavitation bubbles in viscous liquids under ultrasound.

    Science.gov (United States)

    Yasui, Kyuichi; Towata, Atsuya; Tuziuti, Toru; Kozuka, Teruyuki; Kato, Kazumi

    2011-11-01

    The effect of static pressure on acoustic emissions including shock-wave emissions from cavitation bubbles in viscous liquids under ultrasound has been studied by numerical simulations in order to investigate the effect of static pressure on dispersion of nano-particles in liquids by ultrasound. The results of the numerical simulations for bubbles of 5 μm in equilibrium radius at 20 kHz have indicated that the optimal static pressure which maximizes the energy of acoustic waves radiated by a bubble per acoustic cycle increases as the acoustic pressure amplitude increases or the viscosity of the solution decreases. It qualitatively agrees with the experimental results by Sauter et al. [Ultrason. Sonochem. 15, 517 (2008)]. In liquids with relatively high viscosity (∼200 mPa s), a bubble collapses more violently than in pure water when the acoustic pressure amplitude is relatively large (∼20 bar). In a mixture of bubbles of different equilibrium radius (3 and 5 μm), the acoustic energy radiated by a 5 μm bubble is much larger than that by a 3 μm bubble due to the interaction with bubbles of different equilibrium radius. The acoustic energy radiated by a 5 μm bubble is substantially increased by the interaction with 3 μm bubbles.

  4. Bubble Combustion

    Science.gov (United States)

    Corrigan, Jackie

    2004-01-01

    , a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.

  5. Bubble drag reduction requires large bubbles

    CERN Document Server

    Verschoof, Ruben A; Sun, Chao; Lohse, Detlef

    2016-01-01

    In the maritime industry, the injection of air bubbles into the turbulent boundary layer under the ship hull is seen as one of the most promising techniques to reduce the overall fuel consumption. However, the exact mechanism behind bubble drag reduction is unknown. Here we show that bubble drag reduction in turbulent flow dramatically depends on the bubble size. By adding minute concentrations (6 ppm) of the surfactant Triton X-100 into otherwise completely unchanged strongly turbulent Taylor-Couette flow containing bubbles, we dramatically reduce the drag reduction from more than 40% to about 4%, corresponding to the trivial effect of the bubbles on the density and viscosity of the liquid. The reason for this striking behavior is that the addition of surfactants prevents bubble coalescence, leading to much smaller bubbles. Our result demonstrates that bubble deformability is crucial for bubble drag reduction in turbulent flow and opens the door for an optimization of the process.

  6. Investigation on Washing Effects for Nano-Bubble/Surfactant Mixtures in an Alternating Flow

    OpenAIRE

    牛田, 晃臣; 長谷川, 富市; 天木, 桂子; 中島, 俊之; 高橋, 尚幸; 鳴海, 敬倫; Ushida, Akiomi; Hasegawa, Tomiichi; AMAKI, Keiko; Nakajima, Toshiyuki; Takahashi, Naoyuki; Narumi, Takatsune

    2011-01-01

    Laundry wastewater is known to contribute to water pollution, and the need to reduce the amount of detergents used is recognized. Extensive research has focused on the washing effects of micro-bubbles and nano-bubbles, and mechanical work has been found to account for 50% of the washing effect. In the present research, a water/nano-bubble mixture and several types of surfactants were investigated in an alternating flow system. The nano-bubble water achieved a washing rate of about 5% greater ...

  7. Small-scale effects of underwater bubble clouds on ocean reflectance: 3-D modeling results.

    Science.gov (United States)

    Piskozub, Jacek; Stramski, Dariusz; Terrill, Eric; Melville, W Kendall

    2009-07-06

    We examined the effect of individual bubble clouds on remote-sensing reflectance of the ocean with a 3-D Monte Carlo model of radiative transfer. The concentrations and size distribution of bubbles were defined based on acoustical measurements of bubbles in the surface ocean. The light scattering properties of bubbles for various void fractions were calculated using Mie scattering theory. We show how the spatial pattern, magnitude, and spectral behavior of remote-sensing reflectance produced by modeled bubble clouds change due to variations in their geometric and optical properties as well as the background optical properties of the ambient water. We also determined that for realistic sizes of bubble clouds, a plane-parallel horizontally homogeneous geometry (1-D radiative transfer model) is inadequate for modeling water-leaving radiance above the cloud.

  8. Effect of Slotted Anode on Gas Bubble Behaviors in Aluminum Reduction Cell

    Science.gov (United States)

    Sun, Meijia; Li, Baokuan; Li, Linmin; Wang, Qiang; Peng, Jianping; Wang, Yaowu; Cheung, Sherman C. P.

    2017-12-01

    In the aluminum reduction cells, gas bubbles are generated at the bottom of the anode which eventually reduces the effective current contact area and the system efficiency. To encourage the removal of gas bubbles, slotted anode has been proposed and increasingly adopted by some industrial aluminum reduction cells. Nonetheless, the exact gas bubble removal mechanisms are yet to be fully understood. A three-dimensional (3D) transient, multiphase flow mathematical model coupled with magnetohydrodynamics has been developed to investigate the effect of slotted anode on the gas bubble movement. The Eulerian volume of fluid approach is applied to track the electrolyte (bath)-molten aluminum (metal) interface. Meanwhile, the Lagrangian discrete particle model is employed to handle the dynamics of gas bubbles with considerations of the buoyancy force, drag force, virtual mass force, and pressure gradient force. The gas bubble coalescence process is also taken into account based on the O'Rourke's algorithm. The two-way coupling between discrete bubbles and fluids is achieved by the inter-phase momentum exchange. Numerical predictions are validated against the anode current variation in an industrial test. Comparing the results using slotted anode with the traditional one, the time-averaged gas bubble removal rate increases from 36 to 63 pct; confirming that the slotted anode provides more escaping ways and shortens the trajectories for gas bubbles. Furthermore, the slotted anode also reduces gas bubble's residence time and the probability of coalescence. Moreover, the bubble layer thickness in aluminum cell with slotted anode is reduced about 3.5 mm (17.4 pct), so the resistance can be cut down for the sake of energy saving and the metal surface fluctuation amplitude is significantly reduced for the stable operation due to the slighter perturbation with smaller bubbles.

  9. Effect of Slotted Anode on Gas Bubble Behaviors in Aluminum Reduction Cell

    Science.gov (United States)

    Sun, Meijia; Li, Baokuan; Li, Linmin; Wang, Qiang; Peng, Jianping; Wang, Yaowu; Cheung, Sherman C. P.

    2017-08-01

    In the aluminum reduction cells, gas bubbles are generated at the bottom of the anode which eventually reduces the effective current contact area and the system efficiency. To encourage the removal of gas bubbles, slotted anode has been proposed and increasingly adopted by some industrial aluminum reduction cells. Nonetheless, the exact gas bubble removal mechanisms are yet to be fully understood. A three-dimensional (3D) transient, multiphase flow mathematical model coupled with magnetohydrodynamics has been developed to investigate the effect of slotted anode on the gas bubble movement. The Eulerian volume of fluid approach is applied to track the electrolyte (bath)-molten aluminum (metal) interface. Meanwhile, the Lagrangian discrete particle model is employed to handle the dynamics of gas bubbles with considerations of the buoyancy force, drag force, virtual mass force, and pressure gradient force. The gas bubble coalescence process is also taken into account based on the O'Rourke's algorithm. The two-way coupling between discrete bubbles and fluids is achieved by the inter-phase momentum exchange. Numerical predictions are validated against the anode current variation in an industrial test. Comparing the results using slotted anode with the traditional one, the time-averaged gas bubble removal rate increases from 36 to 63 pct; confirming that the slotted anode provides more escaping ways and shortens the trajectories for gas bubbles. Furthermore, the slotted anode also reduces gas bubble's residence time and the probability of coalescence. Moreover, the bubble layer thickness in aluminum cell with slotted anode is reduced about 3.5 mm (17.4 pct), so the resistance can be cut down for the sake of energy saving and the metal surface fluctuation amplitude is significantly reduced for the stable operation due to the slighter perturbation with smaller bubbles.

  10. Effects of bovine serum albumin on a single cavitation bubble.

    Science.gov (United States)

    Qi, Shuibao; Assouar, Badreddine; Chen, Weizhong

    2017-09-01

    The dynamics and sonoluminescence (SL) of a single cavitation bubble in bovine serum albumin (BSA) aqueous solutions have been experimentally and theoretically investigated. A phase-locked integral imaging has been used to record the bubble pulsation evolutions. The results show that, under the optimum driving condition, the endurable driving pressure, maximum radius, radius compression ratio and SL intensity of the cavitation bubble increase correspondingly with the increase of BSA concentrations within the critical micelle concentration, which indicates that the addition of BSA increases the power capability of the cavitation bubble. In addition, BSA molecules dampen the interfacial motion, and especially the rebounds of the bubble after its collapse. BSA molecules modify the dilatational viscosity and elasticity of the bubble wall. A viscoelastic interfacial rheological model that mainly emphasizes on the description of the bubble wall has been introduced and modified to theoretically explain the measured bubble dynamics. A good consensus between the experimental observation and model calculation has been achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Effects of fluid viscosity on a moving sonoluminescing bubble.

    Science.gov (United States)

    Sadighi-Bonabi, Rasoul; Mirheydari, Mona; Rezaee, Nastaran; Ebrahimi, Homa

    2011-08-01

    Based on the quasi-adiabatic model, the parameters of the bubble interior for a moving single bubble sonoluminescence in water, adiponitrile, and N-methylformamide are calculated for various fluid viscosities. By using a complete form of the hydrodynamic force, the bubble trajectory is calculated for a moving single bubble sonoluminescence (m-SBSL). It is found that as the fluid viscosity increases, the unique circular path changes to an ellipsoidal and then linear form and along this incrementally increase of viscosity the light intensity increases. By using the Bremsstrahlung model to describe the bubble radiation, gradual increase of the viscosity results in brighter emissions. It is found that in fluids with higher viscosity the light intensity decreases as time passes.

  12. Comparing the effect of biosurfactant and chemical surfactant on bubble hydrodynamics in a flotation column.

    Science.gov (United States)

    Wang, Huanran; Yang, Jingjing; Lei, Shaomin; Wang, Xinbing

    2013-01-01

    Bubble hydrodynamics is fundamental to the performance of the flotation process widely used in the separation industry. To compare the effect of biosurfactants and chemical synthetic surfactants on bubble hydrodynamics in the flotation process, the motion of a single bubble and the size distribution of bubble swarms in various surfactants (rhamnolipid, tea saponin and Triton X-100) solutions were observed directly using a high-speed video camera in a laboratory scale flotation column. Bubble trajectory, dimensions, velocity and size distribution were then determined through image analysis. The results indicated that the addition of biosurfactants had the same significant effects on bubble motion and size distribution as chemosynthetic surfactants. The biosurfactant effect on bubble behavior was also found to depend on their type and concentration. In general, the effect of tea saponin was stronger than another biosurfactant (rhamnolipid) used in the present study. The present findings implied that some biosurfactants like tea saponin can replace chemosynthetic surfactants in controlling bubble behavior in flotation operation. This will contribute to promoting the use of green environmentally friendly flotation agents in the separation industry.

  13. Microbiota and neurologic diseases: potential effects of probiotics.

    Science.gov (United States)

    Umbrello, Giulia; Esposito, Susanna

    2016-10-19

    The microbiota colonizing the gastrointestinal tract have been associated with both gastrointestinal and extra-gastrointestinal diseases. In recent years, considerable interest has been devoted to their role in the development of neurologic diseases, as many studies have described bidirectional communication between the central nervous system and the gut, the so-called "microbiota-gut-brain axis". Considering the ability of probiotics (i.e., live non-pathogenic microorganisms) to restore the normal microbial population and produce benefits for the host, their potential effects have been investigated in the context of neurologic diseases. The main aims of this review are to analyse the relationship between the gut microbiota and brain disorders and to evaluate the current evidence for the use of probiotics in the treatment and prevention of neurologic conditions. Overall, trials involving animal models and adults have reported encouraging results, suggesting that the administration of probiotic strains may exert some prophylactic and therapeutic effects in a wide range of neurologic conditions. Studies involving children have mainly focused on autism spectrum disorder and have shown that probiotics seem to improve neuro behavioural symptoms. However, the available data are incomplete and far from conclusive. The potential usefulness of probiotics in preventing or treating neurologic diseases is becoming a topic of great interest. However, deeper studies are needed to understand which formulation, dosage and timing might represent the optimal regimen for each specific neurologic disease and what populations can benefit. Moreover, future trials should also consider the tolerability and safety of probiotics in patients with neurologic diseases.

  14. Effect of ultrasound on dynamics characteristic of the cavitation bubble in grinding fluids during honing process.

    Science.gov (United States)

    Guo, Ce; Zhu, Xijing

    2018-03-01

    The effect of ultrasound on generating and controlling the cavitation bubble of the grinding fluid during ultrasonic vibration honing was investigated. The grinding fluid on the surface of the honing stone was measured by utilizing the digital microscope VHX-600ESO. Based on analyzing the cavitation mechanism of the grinding fluid, the bubble dynamics model under conventional honing (CH) and ultrasonic vibration honing (UVH) was established respectively. Difference of dynamic behaviors of the bubble between the cases in UVH and CH was compared respectively, and the effects of acoustic amplitude and ultrasonic frequency on the bubble dynamics were simulated numerically using the Runge-Kutta fourth order method with variable step size adaptive control. Finally, the cavitation intensity of grinding fluids under ultrasound was measured quantitatively using acoustimeter. The results showed that the grinding fluid subjected to ultrasound can generate many bubbles and further forms numerous groups of araneose cavitation bubbles on the surface of the honing stone. The oscillation of the bubble under UVH is more intense than the case under CH, and the maximum velocity of the bubble wall under UVH is higher two magnitudes than the case under CH. For lower acoustic amplitude, the dynamic behaviors of the bubble under UVH are similar to that case under CH. As increasing acoustic amplitude, the cavitation intensity of the bubble is growing increased. Honing pressure has an inhabitation effect on cavitation effect of the grinding fluid. The perfect performance of cavitation of the grinding fluid can be obtained when the device of UVH is in the resonance. However, the cavitation intensity of the grinding fluid can be growing weakened with increasing ultrasonic frequency, when the device of UVH is in the off-resonance. The experimental results agree with the theoretical and numerical analysis, which provides a method for exploring applications of the cavitation effect in

  15. A theoretical study on surfactant adsorption kinetics: effect of bubble shape on dynamic surface tension.

    Science.gov (United States)

    Yang, Ming-Wei; Wei, Hsien-Hung; Lin, Shi-Yow

    2007-12-04

    A planar or spherical fluid-liquid interface was commonly assumed on studying the surfactant adsorption kinetics for a pendant bubble in surfactant solutions. However, the shape of a pendant bubble deviates from a sphere unless the bubble's capillary constant is close to zero. Up to date, the literature has no report about the shape effect on the relaxation of surface tension due to the shape difference between a pendant bubble and a sphere. The dynamic surface tension (DST), based on the actual shape of a pendant bubble with a needle, of the diffusion-controlled process is simulated using a time-dependent finite element method in this work. The shape effect and the existence of a needle on DST are investigated. This numerical simulation resolves also the time-dependent bulk surfactant concentration. The depth of solution needed to satisfy the classical Ward-Tordai infinite-solution assumption was also studied. For a diffusion-controlled adsorption process, bubble shape and needle size are two major factors affecting the DST. The existence of a needle accelerates the bulk diffusion for a small bubble; however, the shape of a large pendant bubble decelerates the bulk diffusion. An example using this method on the DST data of C12E4 is illustrated at the end of this work.

  16. Elastic effects of dilute polymer solution on bubble generation in a microfluidic flow-focusing channel

    Science.gov (United States)

    Kim, Dong Young; Shim, Tae Soup; Kim, Ju Min

    2017-05-01

    Recently, two-phase flow in microfluidics has attracted much attention because of its importance in generating droplets or bubbles that can be used as building blocks for material synthesis and biological applications. However, there are many unresolved issues in understanding droplet and bubble generation processes, especially when complex fluids are involved. In this study, we investigated elastic effects on bubble generation processes in a flow-focusing geometry and the shapes of the produced bubbles flowing through a microchannel. We used dilute polymer solutions with nearly constant shear viscosities so that the shear-thinning effects on bubble generation could be precluded. We observed that a very small amount of polymer (poly(ethylene oxide) at O(10) ppm) significantly affects bubble generation. When the polymer was added to a Newtonian fluid, the fluctuation in bubble size increased notably, which was attributed to the chaotic flow dynamics in the flow-focusing region. In addition, it was demonstrated that the bubbles were thinner along the minor axis in the viscoelastic fluid than they were in the Newtonian fluid. We expect that the current results will contribute to understanding the dynamics of two-phase flow in microchannels and the design and operation of the microfluidic devices to generate microbubbles.

  17. Effect of buoyancy on the motion of long bubbles in horizontal tubes

    Science.gov (United States)

    Atasi, Omer; Khodaparast, Sepideh; Scheid, Benoit; Stone, Howard A.

    2017-09-01

    As a confined long bubble translates along a horizontal liquid-filled tube, a thin film of liquid is formed on the tube wall. For negligible inertial and buoyancy effects, respectively, small Reynolds (Re) and Bond (Bo) numbers, the thickness of the liquid film depends only on the flow capillary number (Ca). However, buoyancy effects are no longer negligible as the diameter of the tube reaches millimeter length scales, which corresponds to finite values of Bo. We perform experiments and theoretical analysis for a long bubble in a horizontal tube to investigate the effect of Bond number (0.05 theory for the film thickness at the front of the bubble in a two-dimensional geometry at low capillary numbers Ca<10-3 and finite Bo to account for the effect of larger Ca. The resulting model shows very good agreement with the present experimental measurements. (ii) Due to the asymmetry in the liquid film thickness and the consequent drainage of the liquid from the top to the bottom of the tube, the bubble is inclined relative to the channel centerline and our side-view visualizations allow direct quantification of the inclination angle, which increases with both Bo and Ca. While the inclination angle at the top is smaller than that at the bottom of the tube, the average of these two values follows the predictions of a mass balance analysis in the central region of the bubble. (iii) The inclination of the bubble causes the thickness of the thin film at the back of the bubble to depend on the length of the bubble, whereas the thickness at the front of the bubble does not depend on the bubble length.

  18. Effect of bubble formation on the dissociation of methane hydrate in water: a molecular dynamics study.

    Science.gov (United States)

    Yagasaki, Takuma; Matsumoto, Masakazu; Andoh, Yoshimichi; Okazaki, Susumu; Tanaka, Hideki

    2014-02-20

    We investigate the dissociation of methane hydrate in liquid water using molecular dynamics simulations. As dissociation of the hydrate proceeds, methane molecules are released into the aqueous phase and eventually they form bubbles. It is shown that this bubble formation, which causes change in the methane concentration in the aqueous phase, significantly affects the dissociation kinetics of methane hydrate. A large system size employed in this study makes it possible to analyze the effects of the change in the methane concentration and the formation of bubbles on the dissociation kinetics in detail. It is found that the dissociation rate decreases with time until the bubble formation and then it turns to increase. It is also demonstrated that methane hydrate can exist as a metastable superheated solid if there exists no bubble.

  19. Effects of Tissue Stiffness, Ultrasound Frequency, and Pressure on Histotripsy-induced Cavitation Bubble Behavior

    Science.gov (United States)

    Vlaisavljevich, Eli; Lin, Kuang-Wei; Warnez, Matthew; Singh, Rahul; Mancia, Lauren; Putnam, Andrew J.; Johnsen, Eric; Cain, Charles; Xu, Zhen

    2015-01-01

    Histotripsy is an ultrasound ablation method that controls cavitation to fractionate soft tissue. In order to effectively fractionate tissue, histotripsy requires cavitation bubbles to rapidly expand from nanometer-sized initial nuclei into bubbles often larger than 50 microns. Using a negative pressure high enough to initiate a bubble cloud and expand bubbles to a sufficient size, histotripsy has been shown capable of completely fractionating soft tissue into acelluar debris resulting in effective tissue removal. Previous work has shown that the histotripsy process is affected by tissue mechanical properties with stiffer tissues showing increased resistance to histotripsy fractionation, which we hypothesize to be caused by impeded bubble expansion in stiffer tissues. In this study, the hypothesis that increases in tissue stiffness causes a reduction in bubble expansion was investigated both theoretically and experimentally. High speed optical imaging was used to capture a series of time delayed images of bubbles produced inside mechanically tunable agarose tissue phantoms using histotripsy pulses produced by 345 kHz, 500 kHz, 1.5 MHz, and 3 MHz histotripsy transducers. The results demonstrated a significant decrease in maximum bubble radius (Rmax) and collapse time (tc) with both increasing Young’s modulus and increasing frequency. Furthermore, results showed that Rmax was not increased by raising the pressure above the intrinsic threshold. Finally, this work demonstrated the potential of using a dual-frequency strategy to modulate the expansion of histotripsy bubbles. Overall, the results of this study improve our understanding of how tissue stiffness and ultrasound parameters affect histotripsy-induced bubble behavior and provide a rational basis to tailor acoustic parameters for treatment of the specific tissues of interest. PMID:25715732

  20. Bubbling effect in the electro-optic delayed feedback oscillator coupled network

    Science.gov (United States)

    Liu, Lingfeng; Lin, Jun; Miao, Suoxia

    2017-03-01

    Synchronization in the optical systems coupled network always suffers from bubbling events. In this paper, we numerically investigate the statistical properties of the synchronization characteristics and bubbling effects in the electro-optic delayed feedback oscillator coupled network with different coupling strength, delay time and gain coefficient. Furthermore, we compare our results with the synchronization properties of semiconductor laser (SL) coupled network, which indicates that the electro-optic delayed feedback oscillator can be better to suppress the bubbling effects in the synchronization of coupled network under the same conditions.

  1. The Effect of Gas Properties on Mesler Bubble Entrainment

    Science.gov (United States)

    Sundberg, R. K.; Saylor, J. R.

    2011-11-01

    Mesler entrainment involves the generation of hundreds of micron size bubbles, frequently distributed in a chandelier- like pattern following the impact of a liquid drop with a bulk surface of the same fluid. To date, research on Mesler entrainment has taken place in air at atmospheric pressure and has therefore neglected to test the influence of gas properties. The results of drop impact studies are presented where a controlled environment was employed consisting of air- helium and air-carbon dioxide mixtures. The dynamic viscosity of pure air at STP is 1 . 85 ×10-5 Pa.s and the kinematic viscosity is 1 . 6 ×10-5 m2 / s . By using air-helium and air-carbon dioxide mixtures, kinematic viscosities ranging from 0.5 to 7 times that of air were attained, with dynamic viscosities ranging 0.8 to 1.0 times that of air. The frequency of occurrence of Mesler entrainment is noted for methanol in these environments and is compared with results gathered in air. The effect of the gas phase viscosities and the Capillary number are discussed.

  2. Effects of microgravity on Marangoni convection and growth characteristic of a single bubble

    Science.gov (United States)

    Yang, Yan; Pan, Liang-ming; Xu, Jian-jun

    2014-07-01

    Based on previous experiments and the volume of fluid (VOF) multiphase model, the growth characteristics of a single bubble have been numerically investigated in a rectangular pool (10×10×25 mm3) under microgravity. The transport of mass and energy during phase change was realized by source terms of the mass and energy equations through user-defined functions (UDF). Under microgravity, the results show that the temperature and the streamline field distribution around the bubble are significantly changed as compared to the ones of terrestrial conditions. The temperature profile at the two-phase interface is no longer a uniform distribution, and the Marangoni flows are more obvious at the two-phase interface. The effects of gravity on the detachment of the bubble are significant: the bubble does not immediately detach from the heating wall under microgravity conditions. The surface tension gradient caused by the Marangoni effect is more significant at lower microgravity. Bubble growth is more complex under microgravity conditions than normal gravity conditions, and it is related to the magnitude of the microgravity: the lower the microgravity, the higher the bubble growth rate. Furthermore, under microgravity, the bubble diameter changes differently, and the fluctuation amplitude of the heat transfer coefficient increases with increasing microgravity.

  3. Effects of laminar separation bubbles and turbulent separation on airfoil stall

    Energy Technology Data Exchange (ETDEWEB)

    Dini, P. [Carleton College, Northfield, MN (United States); Coiro, D.P. [Universita di Napoli (Italy)

    1997-12-31

    An existing two-dimensional, interactive, stall prediction program is extended by improving its laminar separation bubble model. The program now accounts correctly for the effects of the bubble on airfoil performance characteristics when it forms at the mid-chord and on the leading edge. Furthermore, the model can now predict bubble bursting on very sharp leading edges at high angles of attack. The details of the model are discussed in depth. Comparisons of the predicted stall and post-stall pressure distributions show excellent agreement with experimental measurements for several different airfoils at different Reynolds numbers.

  4. Suppressing bubble shielding effect in shock wave lithotripsy by low intensity pulsed ultrasound.

    Science.gov (United States)

    Wang, Jen-Chieh; Zhou, Yufeng

    2015-01-01

    Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment kidney calculi. Because of the bubble shielding effect in the pre-focal region, the acoustic energy delivered to the focus is reduced. Low pulse repetition frequency (PRF) will be applied to dissolve these bubbles for better stone comminution efficiency. In this study, low intensity pulsed ultrasound (LIPUS) beam was aligned perpendicular to the axis of a shock wave (SW) lithotripter at its focus. The light transmission was used to evaluate the compressive wave and cavitation induced by SWs without or with a combination of LIPUS for continuous sonication. It is found that bubble shielding effect becomes dominated with the SW exposure and has a greater significant effect on cavitation than compressive wave. Using the combined wave scheme, the improvement began at the 5th pulse and gradually increased. Suppression effect on bubble shielding is independent on the trigger delay, but increases with the acoustic intensity and pulse duration of LIPUS. The peak negative and integral area of light transmission signal, which present the compressive wave and cavitation respectively, using our strategy at PRF of 1 Hz are comparable to those using SW alone at PRF of 0.1 Hz. In addition, high-speed photography confirmed the bubble activities in both free field and close to a stone surface. Bubble motion in response to the acoustic radiation force by LIPUS was found to be the major mechanism of suppressing bubble shielding effect. There is a 2.6-fold increase in stone fragmentation efficiency after 1000 SWs at PRF of 1 Hz in combination with LIPUS. In summary, combination of SWs and LIPUS is an effective way of suppressing bubble shielding effect and, subsequently, improving cavitation at the focus for a better outcome. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Investigation on Effect of Gravity Level on Bubble Distribution and Liquid Turbulence Modification for Horizontal Channel Bubbly Flow

    Science.gov (United States)

    Pang, M. J.; Wei, J. J.; Yu, B.

    2017-08-01

    Bubbly flows in the horizontal channel or pipe are often seen in industrial engineering fields, so it is very necessary to fully understand hydrodynamics of horizontal bubbly flows so as to improve industrial efficiency and to design an efficient bubbly system. In this paper, in order to fully understand mechanisms of phase distribution and liquid-phase turbulence modulation in the horizontal channel bubbly flow, the influence of gravity level on both of them were investigated in detail with the developed Euler-Lagrange two-way coupling method. For the present investigation, the buoyance on bubbles in both sides of the channel always points to the corresponding wall in order to study the liquid-phase turbulence modulation by bubbles under the symmetric physical condition. The present investigation shows that the gravity level has the important influence on the wall-normal distribution of bubbles and the liquid-phase turbulence modulation; the higher the gravity level is, the more bubbles can overcome the wall-normal resistance to accumulate near the wall, and the more obvious the liquid-phase turbulence modulation is. It is also discovered that interphase forces on the bubbles are various along the wall-normal direction, which leads to the fact that the bubble located in different wall-normal places has a different wall-normal velocity.

  6. Effect of Orifice Diameter on Bubble Generation Process in Melt Gas Injection to Prepare Aluminum Foams

    Science.gov (United States)

    Yuan, Jianyu; Li, Yanxiang; Wang, Ningzhen; Cheng, Ying; Chen, Xiang

    2016-06-01

    The bubble generation process in conditioned A356 alloy melt through submerged spiry orifices with a wide diameter range (from 0.07 to 1.0 mm) is investigated in order to prepare aluminum foams with fine pores. The gas flow rate and chamber pressure relationship for each orifice is first determined when blowing gas in atmospheric environment. The effects of chamber pressure ( P c) and orifice diameter ( D o) on bubble size are then analyzed separately when blowing gas in melt. A three-dimensional fitting curve is obtained illustrating both the influences of orifice diameter and chamber pressure on bubble size based on the experimental data. It is found that the bubble size has a V-shaped relationship with orifice diameter and chamber pressure neighboring the optimized parameter ( D o = 0.25 mm, P c = 0.4 MPa). The bubble generation mechanism is proposed based on the Rayleigh-Plesset equation. It is found that the bubbles will not be generated until a threshold pressure difference is reached. The threshold pressure difference is dependent on the orifice diameter, which determines the time span of pre-formation stage and bubble growth stage.

  7. Assessment of effective thermal conductivity in U–Mo metallic fuels with distributed gas bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang; Casella, Andrew M.; Lavender, Curt A.; Senor, David J.; Burkes, Douglas E.

    2015-07-15

    This work presents a numerical method to assess the relative impact of various microstructural features including grain sizes, nanometer scale intragranular gas bubbles, and larger intergranular gas bubbles in irradiated U–Mo metallic fuels on the effective thermal conductivity. A phase-field model was employed to construct a three-dimensional polycrystalline U–Mo fuel alloy with a given crystal morphology and gas bubble microstructures. An effective thermal conductivity “concept” was taken to capture the effect of polycrystalline structures and gas bubble microstructures with significant size differences on the thermal conductivity. The thermal conductivity of inhomogeneous materials was calculated by solving the heat transport equation. The obtained results are in reasonably good agreement with experimental measurements made on irradiated U–Mo fuel samples containing similar microstructural features. The developed method can be used to predict the thermal conductivity degradation in operating nuclear fuels if the evolution of microstructures is known during operation of the fuel.

  8. Neurological Adverse Effects after Radiation Therapy for Stage II Seminoma

    DEFF Research Database (Denmark)

    Ebbeskov Lauritsen, Liv; Meidahl Petersen, Peter; Daugaard, Gedske

    2012-01-01

    against the tumour bed) with a conventional fractionation of 2 Gy/day, 5 days per week. RT was applied as hockey-stick portals, also called L-fields. In 2 cases, the symptoms fully resolved. Therapeutic irradiation can cause significant injury to the peripheral nerves of the lumbosacral plexus and....../or to the spinal cord. RT is believed to produce plexus injury by both direct toxic effects and secondary microinfarction of the nerves, but the exact pathophysiology of RT-induced injury is unclear. Since reported studies of radiation-induced neurological adverse effects are limited, it is difficult to estimate...... their frequency and outcome. The treatment of neurological symptoms due to RT is symptomatic....

  9. Effects of Swirl Bubble Injection on Mass Transfer and Hydrodynamics for Bubbly Flow Reactors: A Concept Paper

    Directory of Open Access Journals (Sweden)

    Farooqi Ahmad Salam

    2017-01-01

    Full Text Available Bubble flow reactors (BFR are commonly used for various industrial processes in the field of oil and gas production, pharmaceutical industries, biochemical and environmental engineering etc. The operation and performance of these reactors rely heavily on a range of hydrodynamic parameters; prominent among them are geometric configurations including gas injection geometry, operating conditions, mass transfer etc. A huge body of literature is available to describe the optimum design and performance of bubbly flow reactors with conventional bubble injection. Attempts were made to modify gas injection for improved efficiency of BFR’s. However, here instead of modifying the geometry of the gas injection, an attempt has been made to generate swirl bubbles for gaining larger mass transfer between gas and liquid. Here an exceptionally well thought strategies have been used in our numerical simulations towards the design of swirl injection mechanism, whose paramount aspect is to inhibit the rotary liquid motion but facilitates the swirl movement for bubbles in nearly stationary liquid. Our comprehension here is that the swirl motion can strongly affect the performance of bubbly reactor by identifying the changes in hydrodynamic parameters as compared to the conventional bubbly flows. In order to achieve this bubbly flow, an experimental setup has been designed as well as computational fluid dynamic (CFD code was used with to highlight a provision of swirl bubble injection by rotating the sparger plate.

  10. Effect of PEO coating on bubble behavior within a polycarbonate microchannel array: A model for hemodialysis.

    Science.gov (United States)

    Coblyn, Matthew; Truszkowska, Agnieszka; Mohammadi, Mahshid; Heintz, Keely; McGuire, Joseph; Sharp, Kendra; Jovanovic, Goran

    2016-07-01

    Obstruction of fluid flow by stationary bubbles in a microchannel hemodialyzer decreases filtration performance and increases damage to blood cells through flow maldistribution. A polyethylene oxide (PEO)-polybutadiene (PB)-polyethylene oxide surface modification, previously shown to reduce protein fouling and water/air contact angle in polycarbonate microchannel hemodialyzers, can improve microchannel wettability and may reduce bubble stagnation by lessening the resistive forces that compete with fluid flow. In this study, the effect of the PEO-PB-PEO coating on bubble retention in a microchannel array was investigated. Polycarbonate microchannel surfaces were coated with PEO-PB-PEO triblock polymer via radiolytic grafting. Channel obstruction was measured for coated and uncoated microchannels after injecting a short stream of air bubbles into the device under average nominal water velocities of 0.9 to 7.2 cm/s in the channels. The presence of the PEO coating reduced obstruction of microchannels by stationary bubbles within the range of 1.8 to 3.6 cm/s, average nominal velocity. Numerical simulations based on the lattice Boltzmann method indicate that beneficial effects may be due to the maintenance of a lubricating, thin liquid film around the bubble. The determined effective range of the PEO coating for bubble management serves as an important design constraint. These findings serve to validate the multiutility of the PEO-PB-PEO coating (bubble lubrication, biocompatibility, and therapeutic loading). © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 941-948, 2016. © 2015 Wiley Periodicals, Inc.

  11. Neurological AdverseEffects after Radiation Therapyfor Stage II Seminoma

    Directory of Open Access Journals (Sweden)

    Liv Ebbeskov Lauritsen

    2012-08-01

    Full Text Available We report 3 cases of patients with testicular cancer and stage II seminoma who developed neurological symptoms with bilateral leg weakness about 4 to 9 months after radiation therapy (RT. They all received RT to the para-aortic lymph nodes with a total dose of 40 Gy (36 Gy + 4 Gy as a boost against the tumour bed with a conventional fractionation of2 Gy/day, 5 days per week. RT was applied as hockey-stick portals, also called L-fields. In 2 cases, the symptoms fully resolved. Therapeutic irradiation can cause significant injury to the peripheral nerves of the lumbosacral plexus and/or to the spinal cord. RT is believed to produce plexus injury by both direct toxic effects and secondary microinfarction of the nerves, but the exact pathophysiology of RT-induced injury is unclear. Since reported studies of radiation-induced neurological adverse effects are limited, it is difficult to estimate their frequency and outcome. The treatment of neurological symptoms due to RT is symptomatic.

  12. Unintended effects of orphan product designation for rare neurological diseases.

    Science.gov (United States)

    Murphy, Sinéad M; Puwanant, Araya; Griggs, Robert C

    2012-10-01

    Since the introduction of the Orphan Drug Act in 1983, designed to promote development of treatments for rare diseases, at least 378 orphan drugs have been approved. Incentives include financial support, tax credits, and perhaps most importantly, extended market exclusivity. These incentives have encouraged industry interest and accelerated research on rare diseases, allowing patients with orphan diseases access to treatments. However, extended market exclusivity has been associated with unacceptably high drug costs, both for newly developed drugs and for drugs that were previously widely available. We suggest that a paradoxical effect of orphan product exclusivity can be reduced patient access to existing drugs. In addition, the costs of each new drug are arguably unsustainable for patients and for the American health care system. Of all the specialties, neurology has the third highest number of orphan product designations, and neurological diseases account for at least one-fifth of rare diseases. Citing the use of tetrabenazine for chorea in Huntington disease, adrenocorticotropic hormone for infantile spasms, and enzyme replacement therapy with alglucosidase alpha for Pompe disease, we highlight these paradoxical effects. Copyright © 2012 American Neurological Association.

  13. Electric field effects on the dynamics of bubble detachment from an inclined surface

    Science.gov (United States)

    Di Marco, P.; Morganti, N.; Saccone, G.

    2015-11-01

    An experimental apparatus to study bubble detachment from an inclined surface under the action of electric forces is described. It consists of a container filled with FC72 at room temperature and pressure where a train of gas bubbles is injected from an orifice. An electrostatic field can be imposed around the bubble, while the cell can be tilted from 0 to 90°. It is possible to study interface growth with the aid of high-speed cinematography. Since the interface is asymmetrical, a mirror system allowed to acquire, in the same frame, two images at 90° of the bubble. Different inclinations, injection rates and voltages were tested in order to couple the effects of shear gravity and electric field. Curvature and contact angles have been derived with appropriate interpolation methods of the profile. Force balances on the bubble were checked, finding an electric force, which, at first pulls the bubbles from the orifice, then pushes it against the surface. The motion of the center of gravity confirms this behaviour. A power balance has been developed to determine the energy contributions, revealing that surface growth incorporates both the effects of inlet power and electric field.

  14. Bubbles, Banks, and Financial Stability

    OpenAIRE

    Kosuke Aoki; Kalin Nikolov

    2011-01-01

    This paper asks two main questions: (1) What makes some asset price bubbles more costly for the real economy than others? and (2) When do costly bubbles occur? We construct a model of rational bubbles under credit frictions and show that when bubbles held by banks burst this is followed by a costly financial crisis. In contrast, bubbles held by ordinary savers have relatively muted effects. Banks tend to invest in bubbles when financial liberalisation decreases their profitability.

  15. Parametric effects of bubble-microcantilever impacts in a confined channel

    Science.gov (United States)

    Stegmeir, Matthew; Longmire, Ellen; Mantell, Susan

    2008-06-01

    channel width w (0.6≤D/w≤0.75) under laminar flow conditions, channel gradient effects could generate a substantial lift force toward the center of the channel for bubbles approaching offset from the channel centerline. This lift force caused bubbles to cross from one side of the beam to the other; this type of interaction increased the likelihood of splitting and resulted in a number of low-We, high B splitting cases. Bubble impacts with channel walls reduced this phenomenon for D /w≥0.75.

  16. Effect of a soluble surfactant on a finite sized bubble motion in a blood vessel

    Science.gov (United States)

    Swaminathan, T. N.; Mukundakrishnan, K.; Ayyaswamy, P. S.; Eckmann, D. M.

    2009-01-01

    We present detailed results for the motion of a finite sized gas bubble in a blood vessel. The bubble (dispersed phase) size is taken to be such as to nearly occlude the vessel. The bulk medium is treated as a shear thinning Casson fluid and contains a soluble surfactant that adsorbs and desorbs from the interface. Three different vessel sizes, corresponding to a small artery, a large arteriole, and a small arteriole, in normal humans, are considered. The hematocrit (volume fraction of RBCs) has been taken to be 0.45. For arteriolar flow, where relevant, the Fahraeus-Lindqvist effect is taken into account. Bubble motion cause temporal and spatial gradients of shear stress at the cell surface lining the vessel wall as the bubble approaches the cell, moves over it and passes it by. Rapid reversals occur in the sign of the shear stress imparted to the cell surface during this motion. Shear stress gradients together with sign reversals are associated with a recirculation vortex at the rear of the moving bubble. The presence of the surfactant reduces the level of the shear stress gradients imparted to the cell surface as compared to an equivalent surfactant-free system. Our numerical results for bubble shapes and wall shear stresses may help explain phenomena observed in experimental studies related to gas embolism, a significant problem in cardiac surgery and decompression sickness. PMID:20305744

  17. Transient effects in the translation of bubbles insonated with acoustic pulses of finite duration

    Science.gov (United States)

    Igualada-Villodre, Elena; Medina-Palomo, Ana; Vega-Martínez, Patricia; Rodríguez-Rodríguez, Javier

    2018-02-01

    The translation of a bubble under the action of an acoustic forcing finds applications in fields ranging from drug delivery to sonoluminesce. This phenomenon has been widely studied for cases where the amplitude of the forcing remains constant over time. However, in many practical applications, the duration of the forcing is not long enough for the bubble to attain a constant translational velocity, mainly due to the effect of the history force. Here, we develop a formulation, valid in the limit of very viscous flow and small-amplitude acoustic forcing, that allows us to describe the transient dynamics of bubbles driven by acoustic pulses consisting of a finite number of cycles. We also present an asymptotic solution to this theory for the case of a finite-duration sinusoidal pressure pulse. This solution takes into account both the history integral term and the transient period that the bubble needs to achieve steady radial oscillations, being the former dominant during most of the acceleration process. Moreover, by introducing some additional assumptions, we derive a simplified formula that describes fairly well the time evolution of the bubble velocity. Using this solution we show that the convergence to the steady translational velocity, given by the so-called Bjerknes force, occurs rather slowly, namely as $\\tau^{-1/2}$, which explains the slow convergence of the bubble velocity and stresses the importance of taking into account the history force.

  18. Effect of viscosity on bubble and pressure evolution

    Science.gov (United States)

    Visuri, Steven R.; Celliers, Peter M.; Da Silva, Luiz B.; Matthews, Dennis L.

    1997-06-01

    The formation and evolution of acoustic waves and vapor bubbles as a result of laser irradiation have received considerable attention, particularly with respect to angioplasty, thrombolysis, and ophthalmic laser applications. Pressure waves and bubbles have been implicated in undesirable tissue damage yet they can be beneficially utilized while limiting their negative impact. Either planar or spherical pressure waves can be produced through manipulation of irradiation parameters and geometry. An OPO laser emitting approximately 5 ns pulses of visible radiation was delivered through an optical fiber to a cuvette containing dye dissolved in either water or glycerin. Absorption was varied by altering the dye concentration and wavelength of the OPO laser and the spot size was varied by employing multiple sizes of optical fiber. A nitrogen-pumped dye laser with a pulse duration of approximately 5 ns was used as an illumination source. A Mach-Zehnder interferometer technique enabled visualization and quantification of the pressure waves; bubble evolution was monitored with shadowgrams. A comparison was made between experimental and theoretical results for water and glycerin.

  19. Economic Growth with Bubbles

    OpenAIRE

    Alberto Martin

    2010-01-01

    This paper presents a stylized model of economic growth with bubbles. This model views asset price bubbles as a market-generated device to moderate the effects of frictions in financial markets, improving the allocation of investments and raising the capital stock and welfare. It shows that, contrary to conventional wisdom, bubbles can arise even if all investments in the economy are dynamically efficient.

  20. Fetal Cocaine Exposure: Neurologic Effects and Sensory-Motor Delays

    Science.gov (United States)

    Arendt, Robert E.; Minnes, Sonnia; Singer, Lynn T.

    2014-01-01

    SUMMARY Research on animal models demonstrates that fetal cocaine exposure results in neurologic deficits in memory and learning. Although drug effects on human infants are difficult to separate from other environmental influences of a drug-using lifestyle, studies suggest that infants exposed to cocaine in utero have reduced growth, delays in sensory-motor development, attentional deficits, and depressed responsivity to social stimulation. Standard interventions to promote behavioral state regulation in affected infants may be helpful when parents are capable of participating. PMID:25688173

  1. The Impact of the Filter Bubble -- A Simulation Based Framework for Measuring Personalisation Macro Effects in Online Communities

    OpenAIRE

    Gottron, Thomas; Schwagereit, Felix

    2016-01-01

    The term filter bubble has been coined to describe the situation of online users which---due to filtering algorithms---live in a personalised information universe biased towards their own interests.In this paper we use an agent-based simulation framework to measure the actual risk and impact of filter bubble effects occurring in online communities due to content or author based personalisation algorithms. Observing the strength of filter bubble effects allows for opposing the benefits to the ...

  2. Effectiveness of measures of performance during speculative bubbles

    Science.gov (United States)

    Petroni, Filippo; Rotundo, Giulia

    2008-06-01

    Statistical analysis of financial data mostly focused on testing the validity of Brownian motion (Bm). Analyses performed on several time series have shown deviation from the Bm hypothesis, that is at the base of the evaluation of many financial derivatives. We analyze the behavior of performance measures based on maximum drawdown movements ( MDD( T)), testing their stability when the underlying process deviates from the Bm hypothesis. In particular we consider the fractional Brownian motion (fBm), and fluctuations estimated empirically on raw market data. The case study of the rising part of speculative bubbles is reported.

  3. Neurological Effects of Acute Carbon Monoxide Poisoning in Children

    Directory of Open Access Journals (Sweden)

    Coskun YARAR

    2009-11-01

    Full Text Available Carbon monoxide poisoning (COP is one of the most common causes of mortality and morbidity due to poisoning in all over the world. Although the incidence of COP has not been known exactly in the childhood, almost one-third of CO exposures occurred in children. The data regarding COP in children are inconclusive. Children may be more vulnerable to CO exposure than adults as a result of their high respiration and metabolic rates, high oxygen metabolism, and immature central nervous system. Recent researches proposed new theories about neurological effects of CO toxicity. The clinical presentations associated acute COP may be various and nonspecific. Unrecognized CO exposure may lead to significant morbidity and mortality. CO exposed children often become symptomatic earlier, and recover more rapidly, than similarly CO exposed adults. Mild clinical signs and symptoms associated with COP are headache, dizziness, weakness, lethargy, and myalgia; however, severe signs and symptoms such as blurred vision, syncope, convulsion, coma, cardiopulmonary arrest and death can also accompany with COP. Neurologic manifestations can include altered mental status at different degrees, neck stiffness, tremor, ataxia, and positive Babinski's sign. Delayed neurologic sequels (DNS of COP might be seen in children like adults. DNS symptoms and signs in children include memory problems, mental retardation, mutism, fecal and urinary incontinence, motor deficits, facial palsy, psychosis, chronic headache, seizures, and epilepsy. After CO exposure children must be cared to detect and treat DNS. Although hyperbaric oxygen therapy (HBOT is reported to prevent development of DNS, its indications, application duration and procedures are controversial in both of the children and adults. Although their predictive values are limited, exposing to CO more than eight hours and suffering from CO-induced coma, cardiac arrest, lactic acidosis, high COHb levels, and pathologic findings

  4. Singular effective slip length for longitudinal flow over a dense bubble mattress

    Science.gov (United States)

    Schnitzer, Ory

    2016-09-01

    We consider the effective hydrophobicity of a periodically grooved surface immersed in liquid, with trapped shear-free bubbles protruding between the no-slip ridges at a π /2 contact angle. Specifically, we carry out a singular-perturbation analysis in the limit ɛ ≪1 where the bubbles are closely spaced, finding the effective slip length (normalized by the bubble radius) for longitudinal flow along the ridges as π /√{2 ɛ }-(12 /π ) ln2 +(13 π /24 ) √{2 ɛ }+o (√{ɛ }) , the small parameter ɛ being the planform solid fraction. The square-root divergence highlights the strong hydrophobic character of this configuration; this leading singular term (along with the third term) follows from a local lubrication-like analysis of the gap regions between the bubbles, together with general matching considerations and a global conservation relation. The O (1 ) constant term is found by matching with a leading-order solution in the outer region, where the bubbles appear to be touching. We find excellent agreement between our slip-length formula and a numerical scheme recently derived using a unified-transform method [Crowdy, IMA J. Appl. Math. 80, 1902 (2015), 10.1093/imamat/hxv019]. The comparison demonstrates that our asymptotic formula, together with the diametric dilute-limit approximation [Crowdy, J. Fluid Mech. 791, R7 (2016), 10.1017/jfm.2016.88], provides an elementary analytical description for essentially arbitrary no-slip fractions.

  5. Singular effective slip length for longitudinal flow over a dense bubble mattress

    CERN Document Server

    Schnitzer, Ory

    2016-01-01

    We consider the effective hydrophobicity of a Cassie-state liquid above a periodically grooved surface, with trapped shear-free bubbles protruding between no-slip ridges at a pi/2 contact angle. Specifically, we carry out a singular-perturbation analysis in the limit where the bubbles are closely separated, finding the effective slip length for longitudinal flow along the the ridges as a[pi*sqrt(a/d) - 2.53 + o(1)], a being the bubble radius and d the width of the no-slip segments; the square-root divergence with a/d highlights the strong hydrophobic character of this configuration. The leading singular term follows from a local analysis of the gap regions between the bubbles, together with general matching considerations and a global relation linking the applied shear, the protrusion geometry, and the variation of the flow speed transverse to the no-slip ridges. The corrective constant term is found as an integral quantity of the leading-order "outer" problem, where the bubbles appear to be touching. We find...

  6. Effects of CO2 fine bubble injection on reactive crystallization of dolomite from concentrated brine

    Science.gov (United States)

    Tsuchiya, Yuko; Wada, Yoshinari; Hiaki, Toshihiko; Onoe, Kaoru; Matsumoto, Masakazu

    2017-07-01

    In this study, we used the minute gas-liquid interfaces around CO2 fine bubbles as new reaction fields where the crystal nucleation proceeds dominantly and developed a crystallization technique to synthesize dolomite (CaMg(CO3)2) with the desired crystal quality. CaMg(CO3)2 has a crystal structure derived from calcite by ordered replacement of the Ca2+ in calcite by Mg2+. To improve the functionality of the crystal for better utilization of the CaMg(CO3)2, an effective method for an approach to a Mg/Ca ratio of 1.0 and downsizing is indispensable in the crystallization process. In the vicinity of the minute gas-liquid interfaces, the accumulation of Ca2+ and Mg2+ is caused by the negative electric charge on the fine bubbles surface; thus, CaMg(CO3)2 fine particles with a high Mg/Ca ratio can be expected to crystallize. At a reaction temperature (Tr) of 298 K and CO2 flow rate (FCO2) of 11.9 mmol/(L min), CO2 bubbles with an average bubble diameter (dbbl) of 40-2000 μm were continuously supplied to 300 mL of the concentrated brine coming from salt manufacture discharge and CaMg(CO3)2 crystallized within a reaction time of 120 min. Fine bubbles with dbbl of 40 μm were generated using a self-supporting bubble generator by increasing the impeller shear rate under reduced pressure. For comparison, the bubbles with dbbl of 300 or 2000 μm were obtained using a dispersing-type generator. Moreover, FCO2 and Tr were varied as operating parameters during the reactive crystallization supplying CO2 fine bubbles. Consequently, CO2 fine bubble injection is effective for the high-yield crystallization of CaMg(CO3)2 with a Mg/Ca ratio of 1.0 and downsizing of CaMg(CO3)2 particles owing to the acceleration of crystal nucleation caused by the local increase in the supersaturation at the minute gas-liquid interfaces.

  7. Experimental investigation of the effect of liquid viscosity on slug flow in small diameter bubble column

    Directory of Open Access Journals (Sweden)

    Azzopardi Barry John

    2012-04-01

    Full Text Available The effect of liquid viscosity on slug flow in a 50 mm diameter bubble column was investigated experimentally using air-silicone oil as operating fluid with silicone oil of viscosities 5, 100, 1000 and 5000 mPa.s. Data was collected using Electrical Capacitance Tomography (ECT, a non-intrusive advanced instrumentation measuring technique and the high Speed Video Camera, through which the slug parameters such as length of Taylor bubbles and liquid slug, void fraction in Taylor bubbles and liquid slug, slug frequency, film thickness and pressure gradient in the slug, were measured and analyzed. The analysis was done using the void fraction time series, probability density function and power spectral density plots. Superficial gas velocities of 0.02≤Ugs≤0.361 m/s were used in the experiment. It was also observed that as viscosity increases, slug frequency, structure velocity, length of liquid slug, void fraction in liquid slug and void fraction in Taylor bubbles decreases; while the length of Taylor bubble, film thickness and pressure gradient in the slug increases.

  8. Effects of Soluble Surfactant on Lateral Migration of a Bubble in a Shear Flow

    Science.gov (United States)

    Muradoglu, Metin; Tryggvason, Gretar

    2014-11-01

    Motivated by the recent experimental study of Takagi et al. (2008), direct numerical simulations are performed to examine effects of soluble surfactant on the lateral migration of a deformable bubble in a pressure-driven channel flow. The interfacial and bulk surfactant concentration evolution equations are solved fully coupled with the incompressible Navier-Stokes equations. A non-linear equation of state is used to relate interfacial surface tension to surfactant concentration at the interface. A multiscale method is developed to handle the mass exchange between the interface and bulk fluid at high Peclet numbers, using a boundary-layer approximation next to the bubble and a relatively coarse grid for the rest of the flow. It is found that the surfactant induced Marangoni stresses can dominate over the shear-induced lift force and thus alter the behavior of the bubble completely, i.e., the contaminated bubble drifts away from the channel wall and stabilizes at the center of the channel in contrast with the corresponding clean bubble that drifts toward the wall and stabilizes near the wall. The Scientific and Technical Research Council of Turkey (TUBITAK), Grant 112M181 and Turkish Academy of Sciences (TUBA).

  9. Effects of non-condensable gas on the dynamic oscillations of cavitation bubbles

    Science.gov (United States)

    Zhang, Yuning

    2016-11-01

    Cavitation is an essential topic of multiphase flow with a broad range of applications. Generally, there exists non-condensable gas in the liquid and a complex vapor/gas mixture bubble will be formed. A rigorous prediction of the dynamic behavior of the aforementioned mixture bubble is essential for the development of a complete cavitation model. In the present paper, effects of non-condensable gas on the dynamic oscillations of the vapor/gas mixture bubble are numerically investigated in great detail. For the completeness, a large parameter zone (e.g. bubble radius, frequency and ratio between gas and vapor) is investigated with many demonstrating examples. The mechanisms of mass diffusion are categorized into different groups with their characteristics and dominated regions given. Influences of non-condensable gas on the wave propagation (e.g. wave speed and attenuation) in the bubbly liquids are also briefly discussed. Specifically, the minimum wave speed is quantitatively predicted in order to close the pressure-density coupling relationship usually employed for the cavitation modelling. Finally, the application of the present finding on the development of cavitation model is demonstrated with a brief discussion of its influence on the cavitation dynamics. This work was financially supported by the National Natural Science Foundation of China (Project No.: 51506051).

  10. SEARCHING FOR QUARK - GLUON PLASMA (QGP) BUBBLE EFFECTS AT RHIC / LHC.

    Energy Technology Data Exchange (ETDEWEB)

    LINDENBAUM,S.J.; LONGACRE,R.S.; KRAMER,M.

    2003-03-01

    Since the early eighties, we have shared with Leon Van Hove the view that if a QGP were produced in high energy heavy ion colliders that its hadronization products would likely come from small localized in phase space bubbles of plasma. In previous papers we have discussed the case where one to at most a few separated bubbles were produced. In this paper we develop a model based on HIJING to which we added a ring of adjoining multi bubble production, which we believe is a higher cross-section process which dominates the near central rapidity region. We have performed simulations which were designed to be tested by the expected first to become available suitable test data, namely the forthcoming RHIC STAR detector data on 65Gev/n Au colliding with 65 Gev/n Au. We took into account background effects and resonance effects so that a direct comparison with the data, and detailed test of these ideas could be made in the near future. Subsequently 100 Gev/n Au on 100 Gev/n Au forthcoming data can be tested, and of course these techniques, suitably modified by experience can be applied to it and eventually to LHC. We concluded that two charged particle correlations versus the azimuthal angle {Delta}{phi}; vs the opening angle, and vs psuedorapidity {eta}, can detect important bubble signals in the expected background, with statistical significances of 5 - 20{sigma}, provided the reasonably conservative assumptions we have made for bubble production occur. We also predicted charge fluctuation suppressions which increase with the bubble signal, and range from {approx} 5% to 27% in the simulations performed. We demonstrated reasonably that in our model, these charge suppression effects would not significantly be affected by resonances.

  11. Effect of a bubble nucleation model on cavitating flow structure in rarefaction wave

    Science.gov (United States)

    Petrov, N.; Schmidt, A.

    2017-07-01

    This paper explains research examining processes accompanying underwater explosions near the free surface. Particular attention is paid to the effect of heterogeneous nucleation on cavitating flow induced by underwater explosions near the free surface. Variation of the size spectrum of produced bubbles and influence of this process on flow structure are studied. The cavitating liquid is considered as a two-phase bubbly medium described in the framework of the Euler-Lagrange approach treating the carrier phase (liquid) as a continuum and the dispersed phase (bubbles) as a set of test particles. More detailed descriptions of a mathematical model, numerical method, and algorithm validation are observed in the authors' previous paper [see, Petrov and Schmidt (Exp Thermal Fluid Sci 60:367-373, 2015)].

  12. Effects of poverty on cognitive function: a hidden neurologic epidemic.

    Science.gov (United States)

    Bergen, Donna C

    2008-08-05

    Mental retardation is one of the most prevalent neurologic disorders globally. Surveys in high-income countries show 3 to 5 per 1,000 with severe intellectual disability, i.e., IQ below 55. Estimates from developing countries, however, have found prevalence rates from 5 to as much as 22 per 1,000. Protein-energy malnutrition, dietary micronutrient deficiencies, environmental toxins, and lack of early sensory stimulation or the ability to profit from it may contribute to neurodevelopmental disabilities. Tropical diseases such as parasitosis with resultant anemia, malaria, and other infections are major contributory causes. Reduction of poverty and its effects would reduce the present and future burden of mental retardation and cognitive dysfunction, especially in developing countries.

  13. The effect of operating lights on laminar flow: an experimental study using neutrally buoyant helium bubbles.

    Science.gov (United States)

    Refaie, R; Rushton, P; McGovern, P; Thompson, D; Serrano-Pedraza, I; Rankin, K S; Reed, M

    2017-08-01

    The interaction between surgical lighting and laminar airflow is poorly understood. We undertook an experiment to identify any effect contemporary surgical lights have on laminar flow and recommend practical strategies to limit any negative effects. Neutrally buoyant bubbles were introduced into the surgical field of a simulated setup for a routine total knee arthroplasty in a laminar flow theatre. Patterns of airflow were observed and the number of bubbles remaining above the surgical field over time identified. Five different lighting configurations were assessed. Data were analysed using simple linear regression after logarithmic transformation. In the absence of surgical lights, laminar airflow was observed, bubbles were cleared rapidly and did not accumulate. If lights were placed above the surgical field laminar airflow was abolished and bubbles rose from the surgical field to the lights then circulated back to the surgical field. The value of the decay parameter (slope) of the two setups differed significantly; no light (b = -1.589) versus one light (b = -0.1273, p < 0.001). Two lights touching (b = -0.1191) above the surgical field had a similar effect to that of a single light (p = 0. 2719). Two lights positioned by arms outstretched had a similar effect (b = -0.1204) to two lights touching (p = 0.998) and one light (p = 0.444). When lights were separated widely (160 cm), laminar airflow was observed but the rate of clearance of the bubbles remained slower (b = -1.1165) than with no lights present (p = 0.004). Surgical lights have a significantly negative effect on laminar airflow. Lights should be positioned as far away as practicable from the surgical field to limit this effect. Cite this article: Bone Joint J 2017;99-B:1061-6. ©2017 The British Editorial Society of Bone & Joint Surgery.

  14. Effects of surfactant and electrolyte concentrations on bubble formation and stabilization.

    Science.gov (United States)

    Xu, Qingyi; Nakajima, Mitsutoshi; Ichikawa, Sosaku; Nakamura, Nobutaka; Roy, Poritosh; Okadome, Hiroshi; Shiina, Takeo

    2009-04-01

    As interest in the application of microbubbles grows, it is becoming increasingly important to understand the factors affecting their formation and properties in order to effectively generate microbubbles. This paper investigates the effect of surfactant concentration and electrolyte addition on the size distribution and stability of microbubbles. The anionic surfactant sodium dodecyl sulfate (SDS) was used as the surfactant. Minimum bubble diameter and maximum stability were achieved at surfactant concentrations above the CMC. The effect of the electrolyte addition was studied by adding sodium chloride (NaCl) at an SDS concentration below the critical micelle concentration (CMC). Addition of NaCl decreased bubble size and improved bubble preparation to a certain extent. The addition of salt at low concentrations did not affect the surface tension; however, the surface tension was reduced as salt concentration was increased and reached a constant value for NaCl concentrations above 0.25%. The presence of NaCl resulted in a significant decrease in zeta-potential, implying a reduction in the surface charge of SDS micelles. This result suggests that the presence of NaCl may improve the generation and stability of bubbles by enhancing the structures of the adsorption monolayer and interfacial film.

  15. Neurology and diving.

    Science.gov (United States)

    Massey, E Wayne; Moon, Richard E

    2014-01-01

    Diving exposes a person to the combined effects of increased ambient pressure and immersion. The reduction in pressure when surfacing can precipitate decompression sickness (DCS), caused by bubble formation within tissues due to inert gas supersaturation. Arterial gas embolism (AGE) can also occur due to pulmonary barotrauma as a result of breath holding during ascent or gas trapping due to disease, causing lung hyperexpansion, rupture and direct entry of alveolar gas into the blood. Bubble disease due to either DCS or AGE is collectively known as decompression illness. Tissue and intravascular bubbles can induce a cascade of events resulting in CNS injury. Manifestations of decompression illness can vary in severity, from mild (paresthesias, joint pains, fatigue) to severe (vertigo, hearing loss, paraplegia, quadriplegia). Particularly as these conditions are uncommon, early recognition is essential to provide appropriate management, consisting of first aid oxygen, targeted fluid resuscitation and hyperbaric oxygen, which is the definitive treatment. Less common neurologic conditions that do not require hyperbaric oxygen include rupture of a labyrinthine window due to inadequate equalization of middle ear pressure during descent, which can precipitate vertigo and hearing loss. Sinus and middle ear overpressurization during ascent can compress the trigeminal and facial nerves respectively, causing temporary facial hypesthesia and lower motor neuron facial weakness. Some conditions preclude safe diving, such as seizure disorders, since a convulsion underwater is likely to be fatal. Preventive measures to reduce neurologic complications of diving include exclusion of individuals with specific medical conditions and safe diving procedures, particularly related to descent and ascent. © 2014 Elsevier B.V. All rights reserved.

  16. Bubbles formation in helium ion irradiated Cu/W multilayer nanocomposites: Effects on structure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Callisti, M., E-mail: M.Callisti@soton.ac.uk [National Centre for Advanced Tribology at Southampton, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Karlik, M. [Department of Materials, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Trojanova 13, 120 00 Prague 2 (Czech Republic); Polcar, T. [National Centre for Advanced Tribology at Southampton, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, 16627 Prague 6 (Czech Republic)

    2016-05-15

    This study investigates the effects of He bubbles on structural and mechanical properties of sputter-deposited Cu/W multilayers. A multilayer with a periodicity of 10 nm was deposited and subjected to helium ion irradiation with two different fluences. He bubbles formed mostly in Cu layers and their distribution was affected by He concentration and radiation damage. According to SRIM calculations, in low He concentration regions bubbles formed mostly along interfaces, while more homogeneously distributed bubbles were found in Cu layers and along columnar grain boundaries in higher He concentration regions. We suggest that the capability of interfaces to annihilate point defects is weakened by the He bubbles shielding effect. Nanoindentation tests revealed a hardness decrease amounting to ∼0.5 and ∼1 GPa for low and high fluences, respectively. The observed softening effect is attributed to He storage-induced changes in residual stresses and columnar grain boundary/interfacial sliding facilitated by He bubbles. - Highlights: • Cu/W nanocomposites were subjected to He{sup +} irradiation with different fluences. • He bubbles formed more homogeneously in higher He concentration regions. • Decrease in mechanical properties was observed for higher He concentrations. • He bubbles formation facilitated interfacial and grain boundary sliding.

  17. Science Bubbles

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Pedersen, David Budtz

    2013-01-01

    Much like the trade and trait sof bubbles in financial markets,similar bubbles appear on the science market. When economic bubbles burst, the drop in prices causes the crash of unsustainable investments leading to an investor confidence crisis possibly followed by a financial panic. But when...... bubbles appear in science, truth and reliability are the first victims. This paper explores how fashions in research funding and research management may turn science into something like a bubble economy....

  18. Neurological Effects of Exposure to Non-Hypoxic Hypobaria

    Science.gov (United States)

    2014-04-16

    et al. Regional white matter signal abnormalities and cognitive correlates among geriatric patients with treated cardiovascular disease. Brain...neurological decompression sickness in U-2 pilots. Eighty-three altitude chamber personnel (PHY), 105 U-2 pilots (U2P), and 162 age and medically matched...burden is associated with lower neurocognitive test performance. 15. SUBJECT TERMS Neurological decompression sickness , non-hypoxic hypobaria

  19. Neurology clerkship goals and their effect on learning and satisfaction.

    Science.gov (United States)

    Strowd, Roy E; Salas, Rachel Marie E; Cruz, Tiana E; Gamaldo, Charlene E

    2016-02-16

    To define medical student goals in the neurology clerkship and explore the association between goal setting and student performance, clerkship satisfaction, self-directed learning (SDL), and interest in neurology. A 4-year prospective study of consecutive second- to fourth-year medical students rotating through a required 4-week neurology clerkship was conducted. A goal-generating cohort (first 2 years) was enrolled to describe the breadth of student-derived goals. A goal-evaluating cohort (second 2 years) was used to evaluate the frequency of goal achievement and assess associations with performance (e.g., National Board of Medical Examiners [NBME], examination), satisfaction, and SDL behaviors (both based on 5-point Likert scale). Of 440 evaluable students, 201 were goal-generating and 239 goal-evaluating. The top 3 goals were (1) improvement in neurologic examination, (2) understanding neurologic disease, and (3) deriving a differential diagnosis. More than 90% (n = 216/239) of students reported achieving goals. Achievers reported significantly higher clerkship satisfaction (4.2 ± 0.8 vs. 2.8 ± 1.0, p neurology (71% vs. 35%, p = 0.001), and higher observed tendency toward SDL (4.5 ± 0.5 vs. 4.1 ± 0.8, p neurology clerkship. Goal achievers had better adjusted standardized test scores, higher satisfaction, and greater tendency toward SDL. This student-generated, goal-setting program may be particularly appealing to clinicians, educators, and researchers seeking resource-lean mechanisms to improve student experience and performance in the clinical clerkships. © 2015 American Academy of Neurology.

  20. Therapists’ experiences and perceptions of teamwork in neurological rehabilitation: Critical happenings in effective and ineffective teamwork

    OpenAIRE

    Suddick, K; De Souza, LH

    2007-01-01

    This article reports the second part of an exploratory study into occupational therapists` and physiotherapists` perceptions and experiences of team-work in neurological rehabilitation: the factors that were thought to influence effective and ineffective team-work, and the meaning behind effective and ineffective team work in neurological rehabilitation. The study was undertaken through semi-structured interviews of 10 therapists from three different neurological rehabilitation teams based in...

  1. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubbles...... spectroscopy analysis of gases liberated during heating of the glass reveals that small bubbles contain predominantly CH4, CO and CO2, whereas large bubbles bear N2, SO2 and H2S. The methodology utilised in this work can, besides mapping the bubbles in a glass, be applied to shed light on the sources of bubble...

  2. Effects of Gravity on Sheared Turbulence Laden with Bubbles or Droplets

    Science.gov (United States)

    Elghobashi, Said; Lasheras, Juan

    1996-01-01

    This is a new project which started in May 1996. The main objective of the experimental/numerical study is to improve the understanding of the physics of two-way coupling between the dispersed phase and turbulence in a prototypical turbulent shear flow - homogeneous shear, laden with small liquid droplets (in gas) or gaseous bubbles (in liquid). The method of direct numerical simulation (DNS) is used to solve the full three-dimensional, time-dependent Navier-Stokes equations including the terms describing the two-way coupling between the dispersed phase and the carrier flow. The results include the temporal evolution of the three-dimensional energy and dissipation spectra and the rate of energy transfer across the energy spectrum to understand the fundamental physics of turbulence modulation, especially the effects of varying the magnitude of gravitational acceleration. The mean-square displacement and diffusivity of the droplets (or bubbles) of a given size and the preferential accumulation of droplets in low vorticity regions and bubbles in high vorticity regions will be examined in detail for different magnitudes of gravitational acceleration. These numerical results which will be compared with their corresponding measured data will provide a data base from which a subgrid-scale (SGS) model can be developed and validated for use in large-eddy simulation (LES) of particle-laden shear flows. Two parallel sets of experiments will be conducted: bubbles in an immiscible liquid and droplets in air. In both experiments homogeneous shear will be imposed on the turbulent carrier flow. The instantaneous velocities of the fluid and polydispersed-size particles (droplets or bubbles) will be measured simultaneously using a two-component Phase-Doppler Particle Analyzer (PDPA). Also, the velocity statistics and energy spectra for the carrier flow will be measured.

  3. Effects of wood pulp fibre concentration on gas hold-up in bubble ...

    African Journals Online (AJOL)

    Effects of wood pulp fibre concentration on gas hold-up in bubble columns. LK Witika, X Qui. Abstract. No Abstract. Journal of Science and Technology Vol. 9(2) 2005: 35-40. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/jost.v9i2.17546.

  4. Effects of Flow Velocity and Particle Size on Transport of Ultrafine Bubbles in Porous Media

    Science.gov (United States)

    Hamamoto, S.; Nihei, N.; Ueda, Y.; Nishimura, T.

    2015-12-01

    Potential applications of ultrafine bubbles (UFBs) have drawn more attention, especially in environmental engineering fields such as soil/groundwater remediation. Understanding a transport mechanism of UFBs in soils is essential to optimize remediation techniques using UFBs. In this study, column transport experiments using glass beads with different size fraction were conducted, where UFBs created by either air or oxygen were injected to the column with different flow conditions. Effects of particle size and flow velocities on transport characteristics of UFBs were investigated based on the column experiments. The results showed that attachments of UFBs were enhanced under lower water velocity condition, exhibiting more than 50% of UFBs injected were attached inside the column. The mobility of O2-UFBs which have lower zeta potential was higher than that of Air-UFBs. A convection-dispersion model including bubble attachment and detachment terms was applied to the obtained breakthrough curves for each experiment, showing good fitness against the measured data.

  5. Neurological effects of fat embolism syndrome: A case report.

    Science.gov (United States)

    Shacklock, Emma; Gemmell, Andrew; Hollister, Nigel

    2017-11-01

    Fat embolism syndrome is a serious multi-system pathology which classically affects the respiratory system, neurological system and causes a petechial rash. We present the case of a 20-year-old farmer who developed fat embolism syndrome following a traumatic femoral fracture. Features developed within 24 h of injury and necessitated a prolonged stay in Intensive Care. He exhibited significant signs of cerebral fat embolism syndrome including coma and seizures but went on to make full functional recovery. Magnetic resonance imaging is the recommended imaging modality for patients with suspected cerebral fat embolism. In this case, computerised tomography was inconclusive, but magnetic resonance imaging demonstrated the "starfield pattern" of multiple high signal foci on a dark background. Supportive treatment of fat embolism syndrome is required in an appropriate setting, such as High Dependency or Intensive Care, for patients at risk of hypoxia or neurological deterioration. Despite major neurological involvement of fat embolism syndrome, full recovery is described by several cases including ours.

  6. Effect of oxygen breathing and perfluorocarbon emulsion treatment on air bubbles in adipose tissue during decompression sickness

    DEFF Research Database (Denmark)

    Randsoe, T; Hyldegaard, O

    2009-01-01

    Decompression sickness (DCS) after air diving has been treated with success by means of combined normobaric oxygen breathing and intravascular perfluorocarbon (PFC) emulsions causing increased survival rate and faster bubble clearance from the intravascular compartment. The beneficial PFC effect...... has been explained by the increased transport capacity of oxygen and inert gases in blood. However, previous reports have shown that extravascular bubbles in lipid tissue of rats suffering from DCS will initially grow during oxygen breathing at normobaric conditions. We hypothesize that the combined...... effect of normobaric oxygen breathing and intravascular PFC infusion could lead to either enhanced extravascular bubble growth on decompression due to the increased oxygen supply, or that PFC infusion could lead to faster bubble elimination due to the increased solubility and transport capacity in blood...

  7. Warm Pressurant Gas Effects on the Static Bubble Point Pressure for Cryogenic LADs

    Science.gov (United States)

    Hartwig, Jason W.; McQuillen, John; Chato, Daniel J.

    2014-01-01

    This paper presents experimental results for the liquid hydrogen and nitrogen bubble point tests using warm pressurant gases conducted at the NASA Glenn Research Center. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device (LAD). Three fine mesh screen samples (325x2300, 450x2750, 510x3600) were tested in liquid hydrogen and liquid nitrogen using cold and warm non-condensable (gaseous helium) and condensable (gaseous hydrogen or nitrogen) pressurization schemes. Gases were conditioned from 0K - 90K above the liquid temperature. Results clearly indicate degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over non-condensable pressurization. Degradation in the bubble point pressure is inversely proportional to screen porosity, as the coarsest mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.

  8. Effects of thermal annealing on the evolution of He bubbles in zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Shuyan [State Key Laboratory of Nuclear Physics and Technology, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Velisa, Gihan [Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O.B. MG-6, 077125 Magurele (Romania); Debelle, Aurélien [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Bât. 108, 91405 Orsay (France); Yang, Tengfei; Wang, Chenxu [State Key Laboratory of Nuclear Physics and Technology, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Thomé, Lionel [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Bât. 108, 91405 Orsay (France); Xue, Jianming; Yan, Sha [State Key Laboratory of Nuclear Physics and Technology, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Wang, Yugang, E-mail: ygwang@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)

    2014-05-01

    Single crystals of yttria-stabilized zirconia were implanted with 100 keV He ions at two fluences of 9 × 10{sup 16} and 3 × 10{sup 17} cm{sup −2} (5 and 17 He at.%). In order to investigate the effect of thermal annealing on the evolution of both zirconia lattice and implanted He, the samples were annealed at several temperatures ranging from 500 °C to 1400 °C. Three complementary analysis techniques, RBS/C, AFM and TEM were used to study structural damage and surface morphology of the crystal before and after implantation. Results show different He evolution phenomena under the two implantation fluences. It is inferred that, at the lower fluence, the migration and agglomeration of He ions lead to bubble formation after annealing. These bubbles jack up sample surface causing the deformation of surface region and the damage level of surface region increase accordingly. As the temperature continues to increase, He gradually releases and the damage recovers. However, at the higher fluence, the He concentration is sufficient to induce bubble precipitation without annealing. He release and damage recovering is less efficient upon annealing.

  9. The effect of surfactants on path instability of a rising bubble

    Science.gov (United States)

    Tagawa, Yoshiyuki; Takagi, Shu; Matsumoto, Yoichiro

    2013-11-01

    We experimentally investigate the surfactant effect on path instability of an air bubble rising in quiescent water. An addition of surfactant varies the gas-water boundary condition from zero shear stress to non-zero shear stress. We report three main findings: firstly, while the drag force acting on the bubble increases with the surfactant concentration as expected, the lift force shows a non-monotonic behavior; secondly, the transient trajectory starting from helical to zigzag is observed, which has never been reported in the case of purified water; lastly, a bubble with the intermediate slip conditions between free-slip and no-slip show a helical motion for a broad range of the Reynolds number. Aforementioned results are rationalized by considering the adsorption-desorption kinetics of the surfactants on gas-water interface and the wake dynamics. Y.T. thanks for financial support from Grant-in-Aid for JSPS Fellows (20-10701). We also thank for Grant-in-Aid for Scientific Research (B) (21360079).

  10. Measuring temperature effects on nano-bubble growth in tungsten with grazing incidence small angle X-ray scattering

    Directory of Open Access Journals (Sweden)

    Matt Thompson

    2017-08-01

    Full Text Available W samples were exposed to He plasma in the MAGPIE, NAGDIS-II and PISCES-A across a range of sample temperatures between 473–1123K. GISAXS was used to quantify the effect of plasma fluence and W surface temperature on He nano-bubble size distributions. In NAGDIS-II at 873K nano-bubbles are exponentially distributed with mean diameters μ=0.64±0.01nm, similar to the value of μ=0.62±0.01nmfound for the MAGPIE plasma device at the much lower temperature of 473K. Above ∼900K nano-bubbles followed an approximately exponential distribution with μ > 0.72 nm demonstrating a significant increase in nano-bubble sizes at higher temperatures.

  11. The concentration distribution around a growing gas bubble in a bio tissue under the effect of suction process.

    Science.gov (United States)

    Mohammadein, S A

    2014-07-01

    The concentration distribution around a growing nitrogen gas bubble in the blood and other bio tissues of divers who ascend to surface too quickly is obtained by Mohammadein and Mohamed model (2010) for variant and constant ambient pressure through the decompression process. In this paper, the growing of gas bubbles and concentration distribution under the effect of suction process are studied as a modification of Mohammadein and Mohamed model (zero suction). The growth of gas bubble is affected by ascent rate, tissue diffusivity, initial concentration difference, surface tension and void fraction. Mohammadein and Mohamed model (2010) is obtained as a special case from the present model. Results showed that, the suction process activates the systemic blood circulation and delay the growth of gas bubbles in the bio tissues to avoid the incidence of decompression sickness (DCS). Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Effect of dissolved gases in water on acoustic cavitation and bubble growth rate in 0.83 MHz megasonic of interest to wafer cleaning.

    Science.gov (United States)

    Kang, Bong-Kyun; Kim, Min-Su; Park, Jin-Goo

    2014-07-01

    Changes in the cavitation intensity of gases dissolved in water, including H2, N2, and Ar, have been established in studies of acoustic bubble growth rates under ultrasonic fields. Variations in the acoustic properties of dissolved gases in water affect the cavitation intensity at a high frequency (0.83 MHz) due to changes in the rectified diffusion and bubble coalescence rate. It has been proposed that acoustic bubble growth rates rapidly increase when water contains a gas, such as hydrogen faster single bubble growth due to rectified diffusion, and a higher rate of coalescence under Bjerknes forces. The change of acoustic bubble growth rate in rectified diffusion has an effect on the damping constant and diffusivity of gas at the acoustic bubble and liquid interface. It has been suggested that the coalescence reaction of bubbles under Bjerknes forces is a reaction determined by the compressibility and density of dissolved gas in water associated with sound velocity and density in acoustic bubbles. High acoustic bubble growth rates also contribute to enhanced cavitation effects in terms of dissolved gas in water. On the other hand, when Ar gas dissolves into water under ultrasound field, cavitation behavior was reduced remarkably due to its lower acoustic bubble growth rate. It is shown that change of cavitation intensity in various dissolved gases were verified through cleaning experiments in the single type of cleaning tool such as particle removal and pattern damage based on numerically calculated acoustic bubble growth rates. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Effect of in-water recompression with oxygen to 6 msw versus normobaric oxygen breathing on bubble formation in divers.

    Science.gov (United States)

    Blatteau, Jean-Eric; Pontier, Jean-Michel

    2009-07-01

    It is generally accepted that the incidence of decompression sickness (DCS) from hyperbaric exposures is low when few or no bubbles are present in the circulation. To date, no data are available on the influence of in-water oxygen breathing on bubble formation following a provocative dive in man. The purpose of this study was to compare the effect of post-dive hyperbaric versus normobaric oxygen breathing (NOB) on venous circulating bubbles. Nineteen divers carried out open-sea field air dives at 30 msw depth for 30 min followed by a 9 min stop at 3 msw. Each diver performed three dives: one control dive, and two dives followed by 30 min of hyperbaric oxygen breathing (HOB) or NOB; both HOB and NOB started 10 min after surfacing. For HOB, divers were recompressed in-water to 6 msw at rest, whereas NOB was performed in a dry room in supine position. Decompression bubbles were examined by a precordial pulsed Doppler. Bubble count was significantly lower for post-dive NOB than for control dives. HOB dramatically suppressed circulating bubble formation with a bubble count significantly lower than for NOB or controls. In-water recompression with oxygen to 6 msw is more effective in removing gas bubbles than NOB. This treatment could be used in situations of "interrupted" or "omitted" decompression, where a diver returns to the water in order to complete decompression prior to the onset of symptoms. Further investigations are needed before to recommend this protocol as an emergency treatment for DCS.

  14. Bubble properties of heterogeneous bubbly flow in a square bubble column

    NARCIS (Netherlands)

    Bai, W.; Deen, N.G.; Kuipers, J.A.M.

    2010-01-01

    The present work focuses on the measurements of bubble properties in heterogeneous bubbly flows in a square bubble column. A four-point optical fibre probe was used for this purpose. The accuracy and intrusive effect of the optical probe was investigated first. The results show that the optical

  15. Effects of surface orientation on lifetime of near-surface nanoscale He bubble in tungsten

    Science.gov (United States)

    Cui, Jiechao; Fu, Baoqin; Wu, Zhangwen; Hou, Qing

    2017-02-01

    In multiscale modeling of the morphological evolution of plasma facing materials in nuclear fusion reactors, the knowledge of the timescales of the involved physical processes is important. In the present study, a new method based on molecular dynamics simulations was developed to extract the lifetime of helium bubbles near tungsten surfaces. It was found that the lifetime of a helium bubble can be described by the Arrhenius equation. However, the lifetime of a helium bubble depends on the thickness of tungsten film above the helium bubble in the substrate and the bubble size. The influence of surface orientations on the lifetime of helium bubbles was also observed, and the performance of helium bubbles on the (1 1 1) surface is very different from on the (0 0 1) and (0 1 1) surfaces. The role of the helium bubble lifetime in other simulation techniques, such as in kinetic Monte Carlo methods and rate theory, is discussed.

  16. Effects of surface orientation on lifetime of near-surface nanoscale He bubble in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jiechao; Fu, Baoqin; Wu, Zhangwen; Hou, Qing, E-mail: qhou@scu.edu.cn

    2017-02-15

    In multiscale modeling of the morphological evolution of plasma facing materials in nuclear fusion reactors, the knowledge of the timescales of the involved physical processes is important. In the present study, a new method based on molecular dynamics simulations was developed to extract the lifetime of helium bubbles near tungsten surfaces. It was found that the lifetime of a helium bubble can be described by the Arrhenius equation. However, the lifetime of a helium bubble depends on the thickness of tungsten film above the helium bubble in the substrate and the bubble size. The influence of surface orientations on the lifetime of helium bubbles was also observed, and the performance of helium bubbles on the (1 1 1) surface is very different from on the (0 0 1) and (0 1 1) surfaces. The role of the helium bubble lifetime in other simulation techniques, such as in kinetic Monte Carlo methods and rate theory, is discussed.

  17. Bubble systems

    CERN Document Server

    Avdeev, Alexander A

    2016-01-01

    This monograph presents a systematic analysis of bubble system mathematics, using the mechanics of two-phase systems in non-equilibrium as the scope of analysis. The author introduces the thermodynamic foundations of bubble systems, ranging from the fundamental starting points to current research challenges. This book addresses a range of topics, including description methods of multi-phase systems, boundary and initial conditions as well as coupling requirements at the phase boundary. Moreover, it presents a detailed study of the basic problems of bubble dynamics in a liquid mass: growth (dynamically and thermally controlled), collapse, bubble pulsations, bubble rise and breakup. Special emphasis is placed on bubble dynamics in turbulent flows. The analysis results are used to write integral equations governing the rate of vapor generation (condensation) in non-equilibrium flows, thus creating a basis for solving a number of practical problems. This book is the first to present a comprehensive theory of boil...

  18. The effect of water temperature on air entrainment, bubble plumes, and surface foam in a laboratory breaking-wave analog

    Science.gov (United States)

    Callaghan, A. H.; Stokes, M. D.; Deane, G. B.

    2014-11-01

    Air-entraining breaking waves form oceanic whitecaps and play a key role in climate regulation through air-sea bubble-mediated gas transfer, and sea spray aerosol production. The effect of varying sea surface temperature on air entrainment, subsurface bubble plume dynamics, and surface foam evolution intrinsic to oceanic whitecaps has not been well studied. By using a breaking wave analog in the laboratory over a range of water temperatures (Tw = 5°C to Tw = 30°C) and different source waters, we have examined changes in air entrainment, subsurface bubble plumes, and surface foam evolution over the course of a breaking event. For filtered seawater, air entrainment was estimated to increase by 6% between Tw = 6°C and Tw = 30°C, driven by increases of about 43% in the measured surface roughness of the plunging water sheet. After active air entrainment, the rate of loss of air through bubble degassing was more rapid at colder water temperatures within the first 0.5 s of plume evolution. Thereafter, the trend reversed and bubbles degassed more quickly in warmer water. The largest observed temperature-dependent differences in subsurface bubble distributions occurred at radii greater than about 700 μm. Temperature-dependent trends observed in the subsurface bubble plume were mirrored in the temporal evolution of the surface whitecap foam area demonstrating the intrinsic link between surface whitecap foam and the subsurface bubble plume. Differences in foam and plume characteristics due to different water sources were greater than the temperature dependencies for the filtered seawater examined.

  19. Neurologic music therapy: The beneficial effects of music making on neurorehabilitation

    National Research Council Canada - National Science Library

    Altenmüller, Eckart; Schlaug, Gottfried

    2013-01-01

    .... These multimodal effects of music making together with music's ability to tap into the emotion and reward system in the brain can be used to facilitate therapy and rehabilitation of neurological disorders...

  20. Hydrodynamic interaction on large-Reynolds-number aligned bubbles: Drag effects

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Munoz, J., E-mail: jrm@correo.azc.uam.mx [Departamento de Energia, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Centro de Investigacion en Polimeros, Marcos Achar Lobaton No. 2, Tepexpan, 55885 Acolman, Edo. de Mexico (Mexico); Salinas-Rodriguez, E.; Soria, A. [Departamento de IPH, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, 09340 Mexico D.F. (Mexico); Gama-Goicochea, A. [Centro de Investigacion en Polimeros, Marcos Achar Lobaton No. 2, Tepexpan, 55885 Acolman, Edo. de Mexico (Mexico)

    2011-07-15

    Graphical abstract: Display Omitted Highlights: > The hydrodynamic interaction of a pair aligned equal-sized bubbles is analyzed. > The leading bubble wake decreases the drag on the trailing bubble. > A new semi-analytical model for the trailing bubble's drag is presented. > The equilibrium distance between bubbles is predicted. - Abstract: The hydrodynamic interaction of two equal-sized spherical gas bubbles rising along a vertical line with a Reynolds number (Re) between 50 and 200 is analyzed. An approach to estimate the trailing bubble drag based on the search of a proper reference fluid velocity is proposed. Our main result is a new, simple semi-analytical model for the trailing bubble drag. Additionally, the equilibrium separation distance between bubbles is predicted. The proposed models agree quantitatively up to small distances between bubbles, with reported data for 50 {<=} Re {<=} 200. The relative average error for the trailing bubble drag, Er, is found to be in the range 1.1 {<=} Er {<=} 1.7, i.e., it is of the same order of the analytical predictions in the literature.

  1. Hydrodynamic effects of air sparging on hollow fiber membranes in a bubble column reactor.

    Science.gov (United States)

    Xia, Lijun; Law, Adrian Wing-Keung; Fane, Anthony G

    2013-07-01

    Air sparging is now a standard approach to reduce concentration polarization and fouling of membrane modules in membrane bioreactors (MBRs). The hydrodynamic shear stresses, bubble-induced turbulence and cross flows scour the membrane surfaces and help reduce the deposit of foulants onto the membrane surface. However, the detailed quantitative knowledge on the effect of air sparging remains lacking in the literature due to the complex hydrodynamics generated by the gas-liquid flows. To date, there is no valid model that describes the relationship between the membrane fouling performance and the flow hydrodynamics. The present study aims to examine the impact of hydrodynamics induced by air sparging on the membrane fouling mitigation in a quantitative manner. A modelled hollow fiber module was placed in a cylindrical bubble column reactor at different axial heights with the trans-membrane pressure (TMP) monitored under constant flux conditions. The configuration of bubble column without the membrane module immersed was identical to that studied by Gan et al. (2011) using Phase Doppler Anemometry (PDA), to ensure a good quantitative understanding of turbulent flow conditions along the column height. The experimental results showed that the meandering flow regime which exhibits high flow instability at the 0.3 m is more beneficial to fouling alleviation compared with the steady flow circulation regime at the 0.6 m. The filtration tests also confirmed the existence of an optimal superficial air velocity beyond which a further increase is of no significant benefit on the membrane fouling reduction. In addition, the alternate aeration provided by two air stones mounted at the opposite end of the diameter of the bubble column was also studied to investigate the associated flow dynamics and its influence on the membrane filtration performance. It was found that with a proper switching interval and membrane module orientation, the membrane fouling can be effectively

  2. Housing bubble burst or credit crunch effect? Slovenia’s housing market

    Directory of Open Access Journals (Sweden)

    Richard Sendi

    2010-01-01

    Full Text Available As defined by the Investment Dictionary, housing bubbles usually start with an increase in demand in the face of limited supply, which takes a relatively long period of time to replenish and increase. At some point, however, demand decreases or stagnates at the same time supply increases, resulting in a sharp drop in prices known as a bubble burst. During the last two decades, the Slovenian housing market has been characterised by a very high housing demand under circumstances of a limited supply, which may primarily be attributed to the effects of the housing reforms introduced in the early 1990s. As is always the case in such situations, speculators seeking huge quick profits drove house prices to unsustainable levels relative to average incomes. Like in many countries throughout the world, the situation has recently changed. Statistical records show a slight decline in the growth of house prices and there are signs of stagnation in housing demand. These developments have prompted various (contrasting viewpoints among housing experts. Some are convinced that the bubble has finally burst because house prices had reached the highest possible levels that buyers were willing to pay. On the other hand, others argue that house prices would have continued to grow had the credit crunch not occurred, which resulted in the reduced availability of mortgages and therefore depressed demand. These two viewpoints represent the main hypotheses of this discussion. This paper reviews the housing market circumstances over the last two decades and identifies facts that may substantiate or disprove these hypotheses.

  3. Effects of music and music therapy on mood in neurological patients.

    Science.gov (United States)

    Raglio, Alfredo; Attardo, Lapo; Gontero, Giulia; Rollino, Silvia; Groppo, Elisabetta; Granieri, Enrico

    2015-03-22

    Mood disorder and depressive syndromes represent a common comorbid condition in neurological disorders with a prevalence rate that ranges between 20% and 50% of patients with stroke, epilepsy, multiple sclerosis, and Parkinson's disease. Notwithstanding, these conditions are often under-diagnosed and under-treated in the clinical practice and negatively affect the functional recovery, the adherence to treatment, the quality of life, and even the mortality risk. In addition, a bidirectional association between depression and neurological disorders may be possible being that depressive syndromes may be considered as a risk factor for certain neurological diseases. Despite the large amount of evidence regarding the effects of music therapy (MT) and other musical interventions on different aspects of neurological disorders, no updated article reviewing outcomes such as mood, emotions, depression, activity of daily living and so on is actually available; for this reason, little is known about the effectiveness of music and MT on these important outcomes in neurological patients. The aim of this article is to provide a narrative review of the current literature on musical interventions and their effects on mood and depression in patients with neurological disorders. Searching on PubMed and PsycInfo databases, 25 studies corresponding to the inclusion criteria have been selected; 11 of them assess the effects of music or MT in Dementia, 9 explore the efficacy on patients with Stroke, and 5 regard other neurological diseases like Multiple Sclerosis, Amyotrophic Lateral Sclerosis/motor neuron disease, Chronic quadriplegia, Parkinson's Disease, and Acquired Brain dysfunctions. Selected studies are based on relational and rehabilitative music therapy approaches or concern music listening interventions. Most of the studies support the efficacy of MT and other musical interventions on mood, depressive syndromes, and quality of life on neurological patients.

  4. CFD-DEM study of effect of bed thickness for bubbling fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul; Shahnam, Mehrdad

    2011-10-01

    The effect of bed thickness in rectangular fluidized beds is investigated through the CFD–DEM simulations of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and particle kinetic energy. Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20–40 particle diameters. Comparison of velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.

  5. Anti-Tumor Effects From Dendritic Cell-Based Cancer Immunotherapy Using Liposomal Bubbles and Ultrasound

    Science.gov (United States)

    Oda, Yusuke; Suzuki, Ryo; Hirata, Keiichi; Nomura, Tetsuya; Utoguchi, Naoki; Maruyama, Kazuo

    2011-09-01

    Dendritic cell (DC)-based cancer immunotherapy has the potential to be a minimally invasive therapy that could prevent cancer metastasis and recurrence. Recently, in order to induce effective anti-tumor immunity, we developed a novel antigen delivery system for DCs by the combination of ultrasound (US) and liposomal bubbles (Bubble Liposomes: BLs) with entrapped perfluoropropane gas. In this study, we investigated the induction of antigen specific immune responses in vivo and the anti-tumor effect caused by immunization of DCs treated with BLs and US. For the immunization of DCs which had delivered antigen, using BLs and US, the mice induced antigen specific cytotoxic T lymphocytes (CTLs) were found to be the main effector cells in DC-based cancer immunotherapy. In addition, immunization with DCs that had been pulsed with antigen using BLs and US completely suppressed tumor growth Therefore, immunization of DCs with this antigen delivery system has promise for the efficient induction of anti-tumor immune responses.

  6. Effect of Gas- and Liquid-injection Methods on Formation of Bubble and Liquid Slug at Merging Micro T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Kyoung [Kyungnam Univ., Changwon (Korea, Republic of); Lee, Chi Young [Pukyong Nat’l Univ., Busan (Korea, Republic of)

    2016-04-15

    In the present experimental study, the effect of gas- and liquid-injected methods on the formation of bubble and liquid slug at the merging micro T-junction of a square microchannel with dimensions 600 μm × 600 μm was investigated. Nitrogen and water were used as test fluids. The superficial velocities of the liquid and gas were in the range of 0.05 - 1 m/s, and 0.1 - 1 m/s, respectively, where the Taylor flow was observed. The bubble length, liquid slug length, bubble velocity, and bubble generation frequency were measured by analyzing the images captured using a high-speed camera. Under similar inlet superficial velocity conditions, in the case of gas injection to the main channel at the merging T-junction (T{sub g}as-liquid), the lengths of the bubble and liquid slug were longer, and the bubble generation frequency was lower than in the case of liquid injection to the main channel at the merging T-junction (T{sub l}iquid-gas). On the other hand, in both cases, the bubble velocity was almost the same. The previous correlation proposed using experimental data for T{sub l}iquid-gas had predicted the present experimental data of bubble length, bubble velocity, liquid slug length, and bubble generation frequency for T{sub g}as-liquid to be ~24%, ~9%, ~39%, ~55%, respectively.

  7. Bubble, Bubble, Toil and Trouble.

    Science.gov (United States)

    Journal of Chemical Education, 2001

    2001-01-01

    Bubbles are a fun way to introduce the concepts of surface tension, intermolecular forces, and the use of surfactants. Presents two activities in which students add chemicals to liquid dishwashing detergent with water in order to create longer lasting bubbles. (ASK)

  8. Effects of pH on nano-bubble stability and transport in saturated porous media.

    Science.gov (United States)

    Hamamoto, Shoichiro; Takemura, Takato; Suzuki, Kenichiro; Nishimura, Taku

    2017-12-07

    An understanding of nano-scale bubble (NB) transport in porous media is important for potential application of NBs in soil/groundwater remediation. It is expected that the solution chemistry of NB water highly influences the surface characteristics of NBs and porous media and the interaction between them, thus affecting the stability and transport characteristics of NB. In this study, in addition to stability experiments, one-dimensional column transport experiments using glass beads were conducted to investigate the effects of pH on the NB transport behavior. The results showed that the NBs were more stable under higher pH. Column transport experiments revealed that entrapment of NBs, especially larger ones, was enhanced in lower-pH water, likely suggesting pH-dependent NB attachment and physical straining, both of which are also probably influenced by bubble size. Although relatively smaller NBs were released after switching the eluting fluid to one with lower ionic strength, most of the NBs in lower-pH water were still retained in the porous media even altering the chemical condition. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Effects of pH on nano-bubble stability and transport in saturated porous media

    Science.gov (United States)

    Hamamoto, Shoichiro; Takemura, Takato; Suzuki, Kenichiro; Nishimura, Taku

    2018-01-01

    An understanding of nano-scale bubble (NB) transport in porous media is important for potential application of NBs in soil/groundwater remediation. It is expected that the solution chemistry of NB water highly influences the surface characteristics of NBs and porous media and the interaction between them, thus affecting the stability and transport characteristics of NB. In this study, in addition to stability experiments, one-dimensional column transport experiments using glass beads were conducted to investigate the effects of pH on the NB transport behavior. The results showed that the NBs were more stable under higher pH. Column transport experiments revealed that entrapment of NBs, especially larger ones, was enhanced in lower-pH water, likely suggesting pH-dependent NB attachment and physical straining, both of which are also probably influenced by bubble size. Although relatively smaller NBs were released after switching the eluting fluid to one with lower ionic strength, most of the NBs in lower-pH water were still retained in the porous media even altering the chemical condition.

  10. Effective Compressibility of A Bubbly Slurry: II. Fitting Numerical Results to Field Data and Implications

    Energy Technology Data Exchange (ETDEWEB)

    Kam, Seung I.(PEMEX REFINACION); Gauglitz, Phillip A.(BATTELLE (PACIFIC NW LAB)); Rossen, William R.(UNKNOWN)

    2000-12-01

    The goal of this study is to fit model parameters to changes in waste level in response to barometric pressure changes in underground storage tanks at the Hanford Site. This waste compressibility is a measure of the quantity of gas, typically hydrogen and other flammable gases that can pose a safety hazard, retained in the waste. A one-dimensional biconical-pore-network model for compressibility of a bubbly slurry is presented in a companion paper. Fitting these results to actual waste level changes in the tanks implies that bubbles are long in the slurry layer and the ratio of pore-body radius to pore-throat radius is close to one; unfortunately, capillary effects can not be quantified unambiguously from the data without additional information on pore geometry. Therefore determining the quantity of gas in the tanks requires more than just slurry volume data. Similar ambiguity also exists with two other simple models: a capillary-tube model with contact angle hysteresis and spherical-p ore model.

  11. Investigation on Effect of Flow Direction on Hydrodynamics for vertical Channel Bubbly Flow

    Directory of Open Access Journals (Sweden)

    M Pang

    2016-12-01

    Full Text Available In order to fully understand hydrodynamics of the bubbly flow laden with microbubbles, the effect of flow direction on the phase distribution and the liquid–phase turbulence modulation in a vertical channel flow laden with microbubbles was detailedly investigated with a developed numerical method, where the liquid–phase velocity field was solved by direct numerical simulations and the microbubble trajectories were tracked by Newtonian equations of motion. The present investigations show the flow direction has the key influence on the phase distribution and the liquid–phase turbulence modulation; for the bubbly upflow, the overwhelming majority of microbubbles accumulate near the channel wall, the phase distribution display approximately the double–peaked distribution patter, and the liquid–phase turbulence was suppressed; for the bubby downflow, however, the microbubbles are far away from the channel wall to move towards the channel centre, the phase distribution shows roughly the off–center–peaked distribution pattern, and the liquid–phase turbulence was enhanced.

  12. Effects of Anode Flow Field Design on CO2 Bubble Behavior in μDMFC

    Science.gov (United States)

    Li, Miaomiao; Liang, Junsheng; Liu, Chong; Sun, Gongquan; Zhao, Gang

    2009-01-01

    Clogging of anode flow channels by CO2 bubbles is a vital problem for further performance improvements of the micro direct methanol fuel cell (μDMFC). In this paper, a new type anode structure using the concept of the non-equipotent serpentine flow field (NESFF) to solve this problem was designed, fabricated and tested. Experiments comparing the μDMFC with and without this type of anode flow field were implemented using a home-made test loop. Results show that the mean-value, amplitude and frequency of the inlet-to-outlet pressure drops in the NESFF is far lower than that in the traditional flow fields at high μDMFC output current. Furthermore, the sequential images of the CO2 bubbles as well as the μDMFC performance with different anode flow field pattern were also investigated, and the conclusions are in accordance with those derived from the pressure drop experiments. Results of this study indicate that the non-equipotent design of the μDMFC anode flow field can effectively mitigate the CO2 clogging in the flow channels, and hence lead to a significant promotion of the μDMFC performance. PMID:22412313

  13. Effects of Anode Flow Field Design on CO2 Bubble Behavior in μDMFC

    Directory of Open Access Journals (Sweden)

    Gang Zhao

    2009-05-01

    Full Text Available Clogging of anode flow channels by CO2 bubbles is a vital problem for further performance improvements of the micro direct methanol fuel cell (μDMFC. In this paper, a new type anode structure usingthe concept of the non-equipotent serpentine flow field (NESFF to solve this problem was designed, fabricated and tested. Experiments comparing the μDMFC with and without this type of anode flow field were implemented using a home-made test loop. Results show that the mean-value, amplitude and frequency of the inlet-to-outlet pressure drops in the NESFF is far lower than that in the traditional flow fields at high μDMFC output current. Furthermore, the sequential images of the CO2 bubbles as well as the μDMFC performance with different anode flow field pattern were also investigated, and the conclusions are in accordance with those derived from the pressure drop experiments. Results of this study indicate that the non-equipotent design of the µDMFC anode flow field can effectively mitigate the CO2 clogging in the flow channels, and hence lead to a significant promotion of the μDMFC performance.

  14. Bubble impacts with microcantilevers.

    Science.gov (United States)

    Stegmeir, Matthew; Longmire, Ellen; Ali, Mubassar; Mantell, Susan

    2006-11-01

    In the current study, we investigate bubbles in laminar channel flows impacting microcantilever obstacles. Static and resonating cantilevers instrumented with integrated strain gages are mounted perpendicular to the mean flow in a vertically-oriented channel with thickness 2mm, span 10mm, and length 585 mm. Steady, fully-developed upward flows with channel Reynolds numbers based on mean fluid velocity and hydraulic diameter of 0-2500 are considered. Bubbles of diameter 200-1000μm are introduced upstream of the test section, and impacts are observed using a microscope equipped with a high frame rate camera. Observations are made along the length of cantilevers backlit with white light. Strain gage signals are monitored and correlated to impact events. The effect of obstacles on bubble motion and deformation as well as the effect of bubble impacts on the cantilever will be discussed. The flow studies are part of a larger research program examining reliability and performance of vibrating microbeams.

  15. Bubble stimulation efficiency of dinoflagellate bioluminescence.

    Science.gov (United States)

    Deane, Grant B; Stokes, M Dale; Latz, Michael I

    2016-02-01

    Dinoflagellate bioluminescence, a common source of bioluminescence in coastal waters, is stimulated by flow agitation. Although bubbles are anecdotally known to be stimulatory, the process has never been experimentally investigated. This study quantified the flash response of the bioluminescent dinoflagellate Lingulodinium polyedrum to stimulation by bubbles rising through still seawater. Cells were stimulated by isolated bubbles of 0.3-3 mm radii rising at their terminal velocity, and also by bubble clouds containing bubbles of 0.06-10 mm radii for different air flow rates. Stimulation efficiency, the proportion of cells producing a flash within the volume of water swept out by a rising bubble, decreased with decreasing bubble radius for radii less than approximately 1 mm. Bubbles smaller than a critical radius in the range 0.275-0.325 mm did not stimulate a flash response. The fraction of cells stimulated by bubble clouds was proportional to the volume of air in the bubble cloud, with lower stimulation levels observed for clouds with smaller bubbles. An empirical model for bubble cloud stimulation based on the isolated bubble observations successfully reproduced the observed stimulation by bubble clouds for low air flow rates. High air flow rates stimulated more light emission than expected, presumably because of additional fluid shear stress associated with collective buoyancy effects generated by the high air fraction bubble cloud. These results are relevant to bioluminescence stimulation by bubbles in two-phase flows, such as in ship wakes, breaking waves, and sparged bioreactors. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Effect of Shock-Induced Cavitation Bubble Collapse on the damage in the Simulated Perineuronal Net of the Brain.

    Science.gov (United States)

    Wu, Yuan-Ting; Adnan, Ashfaq

    2017-07-13

    The purpose of this study is to conduct modeling and simulation to understand the effect of shock-induced mechanical loading, in the form of cavitation bubble collapse, on damage to the brain's perineuronal nets (PNNs). It is known that high-energy implosion due to cavitation collapse is responsible for corrosion or surface damage in many mechanical devices. In this case, cavitation refers to the bubble created by pressure drop. The presence of a similar damage mechanism in biophysical systems has long being suspected but not well-explored. In this paper, we use reactive molecular dynamics (MD) to simulate the scenario of a shock wave induced cavitation collapse within the perineuronal net (PNN), which is the near-neuron domain of a brain's extracellular matrix (ECM). Our model is focused on the damage in hyaluronan (HA), which is the main structural component of PNN. We have investigated the roles of cavitation bubble location, shockwave intensity and the size of a cavitation bubble on the structural evolution of PNN. Simulation results show that the localized supersonic water hammer created by an asymmetrical bubble collapse may break the hyaluronan. As such, the current study advances current knowledge and understanding of the connection between PNN damage and neurodegenerative disorders.

  17. The effect of gravity-induced pressure gradient on bubble luminescence

    Science.gov (United States)

    Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Dorsaz, Nicolas; Tinguely, Marc; Farhat, Mohamed

    2014-11-01

    The violent collapse of a bubble can heat up its gaseous contents to temperatures exceeding those on the sun's surface, resulting in a short luminescence flash. Occurring at the very moment of the collapse, luminescence must be highly sensitive to the bubble geometry at the preceding final stage. This represents an important feature as any pressure anisotropy in the surrounding liquid will result in a deformation of an initially spherical bubble, inducing a micro-jet that pierces the bubble and makes it experience a toroidal collapse. We therefore present these as complementary phenomena by investigating the link between jets and luminescence of laser-generated single bubbles. Through ultra-high-speed imaging, the micro-jet formation and evolution of a single bubble are observed with unprecedented detail, whilst the bubble light emission is analyzed by means of a spectrometer. The bubble energy and the micro-jet size are controlled by adjusting the laser-pulse and by varying the gravity level aboard ESA parabolic flights, respectively. We here provide systematic evidence on how bubble-jets suppress luminescence in a considerable manner, even in normal gravity where the jet is barely observable. We conclude that gravity must be accounted for in accurate models of luminescence.

  18. The isotope mass effect on chlorine diffusion in dacite melt, with implications for fractionation during bubble growth

    Science.gov (United States)

    Fortin, Marc-Antoine; Watson, E. Bruce; Stern, Richard

    2017-12-01

    Previous experimental studies have revealed that the difference in diffusivity of two isotopes can be significant in some media and can lead to an observable fractionation effect in silicate melts based on isotope mass. Here, we report the first characterization of the difference in diffusivities of stable isotopes of Cl (35Cl and 37Cl). Using a piston-cylinder apparatus, we generated quenched melts of dacitic composition enriched in Cl; from these we fabricated diffusion couples in which Cl atoms were induced to diffuse in a chemical gradient at 1200 to 1350 °C and 1 GPa. We analyzed the run products by secondary ion mass spectrometry (SIMS) for their isotopic compositions along the diffusion profiles, and we report a diffusivity ratio for 37Cl/35Cl of 0.995 ± 0.001 (β = 0.09 ± 0.02). No significant effect of temperature on the diffusivity ratio was discernable over the 150 °C range covered by our experiments. The observed 0.5% difference in diffusivity of the two isotopes could affect our interpretation of isotopic measurements of Cl isotopes in bubble-bearing or degassed magmas, because bubble growth is regulated in part by the diffusive supply of volatiles to the bubble from the surrounding melt. Through numerical simulations, we constrain the extent of Cl isotopic fractionation between bubble and host melt during this process. Bubble growth rates vary widely in nature-which implies a substantial range in the expected magnitude of isotopic fractionation-but plausible growth scenarios lead to Cl isotopic fractionations up to about 5‰ enrichment of 35Cl relative to 37Cl in the bubble. This effect should be considered when interpreting Cl isotopic measurements of systems that have experienced vapor exsolution.

  19. Bubble diagnostics

    Science.gov (United States)

    Visuri, Steven R.; Mammini, Beth M.; Da Silva, Luiz B.; Celliers, Peter M.

    2003-01-01

    The present invention is intended as a means of diagnosing the presence of a gas bubble and incorporating the information into a feedback system for opto-acoustic thrombolysis. In opto-acoustic thrombolysis, pulsed laser radiation at ultrasonic frequencies is delivered intraluminally down an optical fiber and directed toward a thrombus or otherwise occluded vessel. Dissolution of the occlusion is therefore mediated through ultrasonic action of propagating pressure or shock waves. A vapor bubble in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor bubble may be used to directly disrupt the occlusion or as a means of producing a pressure wave. It is desirable to detect the formation and follow the lifetime of the vapor bubble. Knowledge of the bubble formation and lifetime yields critical information as to the maximum size of the bubble, density of the absorbed radiation, and properties of the absorbing material. This information can then be used in a feedback system to alter the irradiation conditions.

  20. An effective automated method for teaching EEG interpretation to neurology residents.

    Science.gov (United States)

    Weber, Daniel; McCarthy, David; Pathmanathan, Jay

    2016-08-01

    EEG interpretation is a fundamental procedural skill in the practice of neurology, but there is no standardized method for educating residents. One-to-one instruction is commonly employed, but is time intensive for supervising physicians, provides arbitrary exposure to normal and abnormal EEG patterns, and often lacks immediate and detailed feedback on performance. Here, we investigated the effectiveness of a novel automated program to assist in educating neurology residents in EEG interpretation. An EEG teaching program was developed to provide neurology residents EEG training less dependent on attending supervision. Residents enter interpretations of full-length pre-selected EEGs and receive immediate feedback based on consensus interpretation of supervising epileptologists. Resident learning was assessed based on performance on matched pre- and post-tests covering common EEG findings including artifacts, normal variants, and abnormalities. Twenty residents were included in this analysis: 12 post-graduate year (PGY) 3 and eight PGY 4 neurology residents. All residents showed improvement, from a mean score of 42.7% (95% CI 36.9-48.5%) on the pre-test to 75.4% (95% CI 70.7-80.2%) on the post-test (pteaching module spread over a 3-week rotation. This pilot study demonstrated the effectiveness of an automated EEG teaching program used by neurology residents in training. This tool could serve as an effective method of supplementing resident education. Copyright © 2016 British Epilepsy Association. All rights reserved.

  1. Filter Bubble vs. Preference Bubble

    OpenAIRE

    Lindström, Hanna-Stiina; Soliman, Gabriela

    2016-01-01

    Tämän opinnäytetyön aiheena oli internetin personointi ja siitä aiheutuva filter bubble –ilmiö. Tarkoituksena oli tutkia kuluttajien suhtautumista ilmiöön, jota Suomessa ei vielä tunnisteta laajasti. Suhtautuminen haluttiin tuoda esiin vastakkainasettelun avulla. Filter bubble –näkökulma edusti tässä työssä ilmiön negatiivista suhtautumistapaa ja preference bubble –näkökulma positiivista. Opinnäytetyö oli tietopaketti yrityksille Filter bubble –ilmiön ominaisuuksista sekä sen käyttäytymisestä...

  2. An Audit of the Effectiveness of Large Group Neurology Tutorials for Irish Undergraduate Medical Students

    LENUS (Irish Health Repository)

    Kearney, H

    2016-07-01

    The aim of this audit was to determine the effectiveness of large group tutorials for teaching neurology to medical students. Students were asked to complete a questionnaire rating their confidence on a ten point Likert scale in a number of domains in the undergraduate education guidelines from the Association of British Neurologists (ABN). We then arranged a series of interactive large group tutorials for the class and repeated the questionnaire one month after teaching. In the three core domains of neurological: history taking, examination and differential diagnosis, none of the students rated their confidence as nine or ten out of ten prior to teaching. This increased to 6% for history taking, 12 % in examination and 25% for differential diagnosis after eight weeks of tutorials. This audit demonstrates that in our centre, large group tutorials were an effective means of teaching, as measured by the ABN guidelines in undergraduate neurology.

  3. The effect of surface tension on steadily translating bubbles in an unbounded Hele-Shaw cell.

    Science.gov (United States)

    Green, Christopher C; Lustri, Christopher J; McCue, Scott W

    2017-05-01

    New numerical solutions to the so-called selection problem for one and two steadily translating bubbles in an unbounded Hele-Shaw cell are presented. Our approach relies on conformal mapping which, for the two-bubble problem, involves the Schottky-Klein prime function associated with an annulus. We show that a countably infinite number of solutions exist for each fixed value of dimensionless surface tension, with the bubble shapes becoming more exotic as the solution branch number increases. Our numerical results suggest that a single solution is selected in the limit that surface tension vanishes, with the scaling between the bubble velocity and surface tension being different to the well-studied problems for a bubble or a finger propagating in a channel geometry.

  4. The neurological effects of brevetoxin on neonatal rats

    Energy Technology Data Exchange (ETDEWEB)

    Tapley, S.R.; Ramsdell, J.S.; Xi, D. [Medical Univ. of South Carolina, Charleston, SC (United States)] [and others

    1994-12-31

    We have investigated the neuroexcitatory and neurodegenerative effects of brevetoxin on neonatal rats. Brevetoxin, a marine-biotoxin that has been implicated in several seafood poisoning incidents, is produced by the dinoflagellate Gymnodinium brevis. Four studies were done: dose response, northern analysis, immunohistochemistry and neurodegeneration. We found that neonatal rats are much more sensitive to brevetoxin than adult rats. The effectiveness of c-fos as a biomarker is being investigated, because of the high basal expression in young animals. The neurodegeneration, although not available yet, should provide valuable information.

  5. Neurological Effects of Honey: Current and Future Prospects

    Directory of Open Access Journals (Sweden)

    Mohammad Mijanur Rahman

    2014-01-01

    Full Text Available Honey is the only insect-derived natural product with therapeutic, traditional, spiritual, nutritional, cosmetic, and industrial value. In addition to having excellent nutritional value, honey is a good source of physiologically active natural compounds, such as polyphenols. Unfortunately, there are very few current research projects investigating the nootropic and neuropharmacological effects of honey, and these are still in their early stages. Raw honey possesses nootropic effects, such as memory-enhancing effects, as well as neuropharmacological activities, such as anxiolytic, antinociceptive, anticonvulsant, and antidepressant activities. Research suggests that the polyphenol constituents of honey can quench biological reactive oxygen species and counter oxidative stress while restoring the cellular antioxidant defense system. Honey polyphenols are also directly involved in apoptotic activities while attenuating microglia-induced neuroinflammation. Honey polyphenols are useful in improving memory deficits and can act at the molecular level. Therefore, the ultimate biochemical impact of honey on specific neurodegenerative diseases, apoptosis, necrosis, neuroinflammation, synaptic plasticity, and behavior-modulating neural circuitry should be evaluated with appropriate mechanistic approaches using biochemical and molecular tools.

  6. Nanosecond Discharge in Bubbled Liquid n-Heptane: Effects of Gas Composition and Water Addition

    KAUST Repository

    Hamdan, Ahmad

    2016-08-30

    Recently, an aqueous discharge reactor was developed to facilitate reformation of liquid fuels by in-liquid plasma. To gain a microscopic understanding of the physical elements behind this aqueous reactor, we investigate nanosecond discharges in liquid n-heptane with single and double gaseous bubbles in the gap between electrodes. We introduce discharge probability (DP) to characterize the stochastic nature of the discharges, and we investigate the dependence of DP on the gap distance, applied voltage, gaseous bubble composition, and the water content in n-heptane/distilled-water emulsified mixtures. Propagation of a streamer through the bubbles indicates no discharges in the liquids. DP is controlled by the properties of the gaseous bubble rather than by the composition of the liquid mixture in the gap with a single bubble; meanwhile, DP is determined by the dielectric permittivity of the liquid mixture in the gap with double bubbles, results that are supported by static electric field simulations. We found that a physical mechanism of increasing DP is caused by an interaction between bubbles and an importance of the dielectric permittivity of a liquid mixture on the local enhancement of field intensity. We also discuss detailed physical characteristics, such as plasma lifetime and electron density within the discharge channel, by estimating from measured emissions with a gated-intensified charge-coupled device and by using spectroscopic images, respectively. © 1973-2012 IEEE.

  7. Eulerian simulations of bubble behaviour in a two-dimensional gas-solid bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Lu Huilin; Liu Wentie; Zhao Guangbo; He Yurong [Harbin Institute of Technology (China). Dept. of Power Engineering; Li Feng [Jiangxi Boiler Co. Ltd., Nanchang (China)

    2002-07-01

    In the present study, the CFD model is based on a two-fluid model extended with the kinetic theory of granular flow. The simulation results of bubble diameter and bubble rise velocity are compared to the Darton equation and the Davidson model in a free bubbling fluidized bed. The predicted values are in reasonable agreement with the values from the Darton bubble size equation and the Davidson model for isolated bubbles. It is shown that the break-up and direct wall interaction effects influence the dynamic bubble behavior in the free bubbling fluidized beds. (author)

  8. Droplets, Bubbles and Ultrasound Interactions.

    Science.gov (United States)

    Shpak, Oleksandr; Verweij, Martin; de Jong, Nico; Versluis, Michel

    2016-01-01

    The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to circulate within blood vessels. Perfluorocarbon liquid droplets can be a potential new generation of microbubble agents as ultrasound can trigger their conversion into gas bubbles. Prior to activation, they are at least five times smaller in diameter than the resulting bubbles. Together with the violent nature of the phase-transition, the droplets can be used for local drug delivery, embolotherapy, HIFU enhancement and tumor imaging. Here we explain the basics of bubble dynamics, described by the Rayleigh-Plesset equation, bubble resonance frequency, damping and quality factor. We show the elegant calculation of the above characteristics for the case of small amplitude oscillations by linearizing the equations. The effect and importance of a bubble coating and effective surface tension are also discussed. We give the main characteristics of the power spectrum of bubble oscillations. Preceding bubble dynamics, ultrasound propagation is introduced. We explain the speed of sound, nonlinearity and attenuation terms. We examine bubble ultrasound scattering and how it depends on the wave-shape of the incident wave. Finally, we introduce droplet interaction with ultrasound. We elucidate the ultrasound-focusing concept within a droplets sphere, droplet shaking due to media compressibility and droplet phase-conversion dynamics.

  9. Effects of temporal density variation and convergent geometry on nonlinear bubble evolution in classical Rayleigh-Taylor instability.

    Science.gov (United States)

    Goncharov, V N; Li, D

    2005-04-01

    Effects of temporal density variation and spherical convergence on the nonlinear bubble evolution of single-mode, classical Rayleigh-Taylor instability are studied using an analytical model based on Layzer's theory [Astrophys. J. 122, 1 (1955)]. When the temporal density variation is included, the bubble amplitude in planar geometry is shown to asymptote to integral(t)U(L)(t')rho(t')dt'/rho(t), where U(L) = square root of (g/(C(g)k)) is the Layzer bubble velocity, rho is the fluid density, and C(g) = 3 and C(g) = 1 for the two- and three-dimensional geometries, respectively. The asymptotic bubble amplitude in a converging spherical shell is predicted to evolve as eta approximately etam(-/r0//(lU(L)sp-eta/r0), where r0 is the outer shell radius, eta(t) = integral(t)U(L)sp(t')rho(t') r(0)2(t')dt'/rho(t)r(0)2(t), U(L)(sp) = square root of (-r0(t)r0(t)/l), m(t) = rho(t)r(0)3(t), and l is the mode number.

  10. Combined effects of radiation damage and He accumulation on bubble nucleation in Gd2Ti2O7

    Science.gov (United States)

    Taylor, Caitlin A.; Patel, Maulik K.; Aguiar, Jeffery A.; Zhang, Yanwen; Crespillo, Miguel L.; Wen, Juan; Xue, Haizhou; Wang, Yongqiang; Weber, William J.

    2016-10-01

    Pyrochlores have long been considered as host phases for long-term immobilization of radioactive waste nuclides that would undergo α-decay for hundreds of thousands of years. This work utilizes ion-beam irradiations to examine the combined effects of radiation damage and He accumulation on bubble formation in Gd2Ti2O7 over relevant waste-form timescales. Helium bubbles are not observed in pre-damaged Gd2Ti2O7 implanted with 2 × 1016 He/cm2, even after post-implantation irradiations with 7 MeV Au3+ at 300, 500, and 700 K. However, He bubbles with average diameters of 1.5 nm and 2.1 nm are observed in pre-damaged (amorphous) Gd2Ti2O7 and pristine Gd2Ti2O7, respectively, after implantation of 2 × 1017 He/cm2. The critical He concentration for bubble nucleation in Gd2Ti2O7 is estimated to be 6 at.% He.

  11. Comparison of the Effects of Play Dough and Bubble Making Distraction Techniques on Venepuncture Pain Intensity in Children

    Directory of Open Access Journals (Sweden)

    Shahrokh Maghsoudi

    2015-12-01

    Full Text Available Background: Venepuncture is a minimally invasive procedure, which is commonly performed in hospitals; if the pain is inadequately managed, it can cause negative feelings in children. Distraction can reduce pain through affecting the central nervous system and releasing neurotransmitters that inhibit pain. Aim: In this study, we aimed to compare the effects of play-dough and bubble making as distraction techniques on the intensity of venepuncture pain in children. Method: In this randomized, controlled, clinical trial, 90 children aged three to six years old, were randomly allocated to the three groups of  play dough, bubble making, and control (n=30 for each group. This study was performed in Qaem, Imam Reza, and Dr. Sheikh hospitals of Mashhad, Iran, in 2015. The interventions consisted of using play dough and bubble making, which were started five minutes before venepuncture. Following the intervention, pain assessment was performed using Wong-Baker Faces Pain Rating Scale. Chi-square, Fisher’s exact, and One-way ANOVA tests were performed to analyze the data, using SPSS version 16. Results: The mean of pain intensity in the play dough, bubble making, and control groups was 5.1±1.8 6.2±1.4, and 8.2±1.5, respectively (out of ten. One-way ANOVA reflected a significant difference between the three groups (P

  12. Bubble-Facilitated VOC Transport from LNAPL Smear Zones and Its Potential Effect on Vapor Intrusion.

    Science.gov (United States)

    Soucy, Nicole C; Mumford, Kevin G

    2017-03-07

    Most conceptual and mathematical models of soil vapor intrusion assume that the transport of volatile organic compounds (VOCs) from a source toward a building is limited by diffusion through the soil gas. Under conditions where advection occurs, transport rates are higher and can lead to higher indoor air concentrations. Advection-dominated conditions can be created by gas bubble flow in the saturated zone. A series of laboratory column experiments were conducted to measure mass flux due to bubble-facilitated VOC transport from light nonaqueous phase liquid (LNAPL) smear zones. Smear zones that contained both LNAPL residual and trapped gas, as well as those that contained only LNAPL residual, were investigated. Results showed that the VOC mass flux due to bubble-facilitated transport was orders-of-magnitude higher than under diffusion-limited conditions. Results also showed that the mass flux due to bubble-facilitated transport was intermittent, and increased with an increased supply of dissolved gases.

  13. Soap Bubbles on a Cold Day.

    Science.gov (United States)

    Waiveris, Charles

    1994-01-01

    Discusses the effects of blowing bubbles in extremely cold weather. Describes the freezing conditions of the bubbles and some physical properties. Suggests using the activity with all ages of students. (MVL)

  14. Impact of bubble size in a rat model of cerebral air microembolization

    Science.gov (United States)

    2013-01-01

    Background Cerebral air microembolization (CAM) is a frequent side effect of diagnostic or therapeutic interventions. Besides reduction of the amount of bubbles, filter systems in the clinical setting may also lead to a dispersion of large gas bubbles and therefore to an increase of the gas–liquid-endothelium interface. We evaluated the production and application of different strictly defined bubble diameters in a rat model of CAM and assessed functional outcome and infarct volumes in relation to the bubble diameter. Methods Gas emboli of defined number and diameter were injected into the carotid artery of rats. Group I (n = 7) received 1800 air bubbles with a diameter of 45 μm, group II (n = 7) 40 bubbles of 160 μm, controls (n = 6) saline without gas bubbles; group I and II yielded the same total injection volume of air with 86 nl. Functional outcome was assessed at baseline, after 4 h and 24 h following cerebral MR imaging and infarct size calculation. Results Computer-aided evaluation of bubble diameters showed high constancy (group I: 45.83 μm ± 2.79; group II: 159 μm ± 1.26). Animals in group I and II suffered cerebral ischemia and clinical deterioration without significant difference. Infarct sizes did not differ significantly between the two groups (p = 0.931 u-test). Conclusions We present further development of a new method, which allows reliable and controlled CAM with different bubble diameters, producing neurological deficits due to unilateral cerebral damage. Our findings could not display a strong dependency of stroke frequency and severity on bubble diameter. PMID:24139539

  15. Marangoni Effects on the Bubble Dynamics in a Pressure Driven Flow

    Science.gov (United States)

    Park, Chang-Won; Maruvada, S. R. K.

    1996-01-01

    The motion of air bubbles and water drops in a Hele-Shaw cell filled with a silicone oil has been studied experimentally and theoretically. By adding a predetermined amount of a surfactant to the water drops we attempted to investigate the surfactant influence systematically. While the motion of air bubbles was in reasonable agreement with the predictions of Taylor and Saffman, water drops behaved quite differently in that the translational velocities were smaller by an order of magnitude and their shapes were very unusual as observed previously by Kopf-Sill and Homsy. Assuming that the surrounding fluid wets the solid wall and the bubble (or the drop) surface is rigid due to the surfactant influence, we have estimated the translational velocity of an elliptic bubble. The calculated velocities were in good agreement with the observations indicating that the surfactant influence could retard the bubble motion significantly. The present study also indicates that the unusual bubble shapes are also due to the surfactant influence.

  16. Formation of methane nano-bubbles during hydrate decomposition and their effect on hydrate growth.

    Science.gov (United States)

    Bagherzadeh, S Alireza; Alavi, Saman; Ripmeester, John; Englezos, Peter

    2015-06-07

    Molecular dynamic simulations are performed to study the conditions for methane nano-bubble formation during methane hydrate dissociation in the presence of water and a methane gas reservoir. Hydrate dissociation leads to the quick release of methane into the liquid phase which can cause methane supersaturation. If the diffusion of methane molecules out of the liquid phase is not fast enough, the methane molecules agglomerate and form bubbles. Under the conditions of our simulations, the methane-rich quasi-spherical bubbles grow to become cylindrical with a radius of ∼11 Å. The nano-bubbles remain stable for about 35 ns until they are gradually and homogeneously dispersed in the liquid phase and finally enter the gas phase reservoirs initially set up in the simulation box. We determined that the minimum mole fraction for the dissolved methane in water to form nano-bubbles is 0.044, corresponding to about 30% of hydrate phase composition (0.148). The importance of nano-bubble formation to the mechanism of methane hydrate formation, growth, and dissociation is discussed.

  17. Leverage bubble

    Science.gov (United States)

    Yan, Wanfeng; Woodard, Ryan; Sornette, Didier

    2012-01-01

    Leverage is strongly related to liquidity in a market and lack of liquidity is considered a cause and/or consequence of the recent financial crisis. A repurchase agreement is a financial instrument where a security is sold simultaneously with an agreement to buy it back at a later date. Repurchase agreement (repo) market size is a very important element in calculating the overall leverage in a financial market. Therefore, studying the behavior of repo market size can help to understand a process that can contribute to the birth of a financial crisis. We hypothesize that herding behavior among large investors led to massive over-leveraging through the use of repos, resulting in a bubble (built up over the previous years) and subsequent crash in this market in early 2008. We use the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles and behavioral finance to study the dynamics of the repo market that led to the crash. The JLS model qualifies a bubble by the presence of characteristic patterns in the price dynamics, called log-periodic power law (LPPL) behavior. We show that there was significant LPPL behavior in the market before that crash and that the predicted range of times predicted by the model for the end of the bubble is consistent with the observations.

  18. Low frequency sound scattering from spherical assemblages of bubbles using effective medium theory.

    Science.gov (United States)

    Hahn, Thomas R

    2007-12-01

    The determination of the acoustic field scattered by an underwater assembly of gas bubbles or similar resonant monopole scatterers is of considerable theoretical and practical interest. This problem is addressed from a theoretical point of view within the framework of the effective medium theory for the case of spherically shaped assemblages. Although being valid more generally, the effective medium theory is an ideal instrument to study multiple scattering effects such as low frequency collective resonances, acoustically coupled breathing modes of the entire assembly. Explicit expressions for the scattering amplitude and cross sections are derived, as well as closed form expressions for the resonance frequency and spectral shape of the fundamental collective mode utilizing analytical S-matrix methods. This approach allows, in principle, a simultaneous inversion for the assembly radius and void fraction directly from the scattering cross sections. To demonstrate the validity of the approach, the theory is applied to the example of idealized, spherically shaped schools of swim bladder bearing fish. The analytic results of the theory are compared to numerical first-principle benchmark computations and excellent agreement is found, even for densely packed schools and frequencies across the bladder resonance.

  19. Hadron bubbles in nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Troitskii, M.A.; Khodel' , V.A.

    1983-08-25

    Nonlinear effects in the interaction of hadrons with a nucleus are analyzed. It is shown that K/sup +/ mesons form bubbles in nuclear matter which are similar to electron bubbles in liquid helium. Charged pions produced in collisions of heavy relativistic ions may collect and form droplets approx.5--7 Fm in size containing approx.10/sup 2/ particles.

  20. Optical Spring Effect in Micro-Bubble Resonators and Its Application for the Effective Mass Measurement of Optomechanical Resonant Mode

    Directory of Open Access Journals (Sweden)

    Zhenmin Chen

    2017-09-01

    Full Text Available In this work, we present a novel approach for obtaining the effective mass of mechanical vibration mode in micro-bubble resonators (MBRs. To be specific, the effective mass is deduced from the measurement of optical spring effect (OSE in MBRs. This approach is demonstrated and applied to analyze the effective mass of hollow MBRs and liquid-filled MBRs, respectively. It is found that the liquid-filled MBRs has significantly stronger OSE and a less effective mass than hollow MBRs, both of the extraordinary behaviors can be beneficial for applications such as mass sensing. Larger OSE from higher order harmonics of the mechanical modes is also observed. Our work paves a way towards the developing of OSE-based high sensitive mass sensor in MBRs.

  1. Malaria with neurological involvement in Ugandan children: effect on cognitive ability, academic achievement and behaviour.

    Science.gov (United States)

    Bangirana, Paul; Musisi, Seggane; Boivin, Michael J; Ehnvall, Anna; John, Chandy C; Bergemann, Tracy L; Allebeck, Peter

    2011-11-03

    Malaria is a leading cause of ill health and neuro-disability in children in sub-Saharan Africa. Impaired cognition is a common outcome of malaria with neurological involvement. There is also a possibility that academic achievement may be affected by malaria with neurological involvement given the association between cognitive ability and academic achievement. This study investigated the effect of malaria with neurological involvement on cognitive ability, behaviour and academic achievement. This prospective case-control study was carried out in Kampala City, Uganda between February 2008 and October 2010. Sixty-two children with a history of malaria with neurological involvement were followed up and given assessments for cognitive ability (working memory, reasoning, learning, visual spatial skills and attention), behaviour (internalizing and externalizing problems) and academic achievement (arithmetic, spelling and reading) three months after the illness. Sixty-one community controls recruited from the homes or neighbouring families of the cases were also given the same assessments. Tests scores of the two groups were compared using analysis of covariance with age, sex, level of education, nutritional status and quality of the home environment as covariates. This study was approved by the relevant ethical bodies and informed consent sought from the caregivers. Children in the malaria group had more behavioural problems than the community controls for internalizing problems (estimated mean difference = -3.71, 95% confidence interval (CI), = -6.34 to -1.08, p = 0.007). There was marginal evidence of lower attention scores (0.40, CI = -0.05 to 0.86, p = 0.09). However, excluding one child from the analyses who was unable to perform the tests affected the attention scores to borderline significance (0.32, CI, = 0.01 to 0.62, p = 0.05). No significant differences were observed in other cognitive abilities or in academic achievement scores. Malaria with neurological

  2. Malaria with neurological involvement in Ugandan children: effect on cognitive ability, academic achievement and behaviour

    Directory of Open Access Journals (Sweden)

    Bangirana Paul

    2011-11-01

    Full Text Available Abstract Background Malaria is a leading cause of ill health and neuro-disability in children in sub-Saharan Africa. Impaired cognition is a common outcome of malaria with neurological involvement. There is also a possibility that academic achievement may be affected by malaria with neurological involvement given the association between cognitive ability and academic achievement. This study investigated the effect of malaria with neurological involvement on cognitive ability, behaviour and academic achievement. Methods This prospective case-control study was carried out in Kampala City, Uganda between February 2008 and October 2010. Sixty-two children with a history of malaria with neurological involvement were followed up and given assessments for cognitive ability (working memory, reasoning, learning, visual spatial skills and attention, behaviour (internalizing and externalizing problems and academic achievement (arithmetic, spelling and reading three months after the illness. Sixty-one community controls recruited from the homes or neighbouring families of the cases were also given the same assessments. Tests scores of the two groups were compared using analysis of covariance with age, sex, level of education, nutritional status and quality of the home environment as covariates. This study was approved by the relevant ethical bodies and informed consent sought from the caregivers. Results Children in the malaria group had more behavioural problems than the community controls for internalizing problems (estimated mean difference = -3.71, 95% confidence interval (CI, = -6.34 to -1.08, p = 0.007. There was marginal evidence of lower attention scores (0.40, CI = -0.05 to 0.86, p = 0.09. However, excluding one child from the analyses who was unable to perform the tests affected the attention scores to borderline significance (0.32, CI, = 0.01 to 0.62, p = 0.05. No significant differences were observed in other cognitive abilities or in academic

  3. Oscillating drop/bubble tensiometry: effect of viscous forces on the measurement of interfacial tension.

    Science.gov (United States)

    Freer, E M; Wong, H; Radke, C J

    2005-02-01

    The oscillating drop/bubble technique is increasingly popular for measuring the interfacial dilatational properties of surfactant/polymer-laden fluid/fluid interfaces. A caveat of this technique, however, is that viscous forces are important at higher oscillation frequencies or fluid viscosities; these can affect determination of the interfacial tension. Here, we experimentally quantify the effect of viscous forces on the interfacial-tension measurement by oscillating 100 and 200 cSt poly(dimethylsiloxane) (PDMS) droplets in water at small amplitudes and frequencies ranging between 0.01 and 1 Hz. Due to viscous forces, the measured interfacial tension oscillates sinusoidally with the same frequency as the oscillation of the drop volume. The tension oscillation precedes that of the drop volume, and the amplitude varies linearly with Capillary number, Ca=DeltamuomegaDeltaV/gammaa(2), where Deltamu=mu(D)-mu is the difference between the bulk Newtonian viscosities of the drop and surrounding continuous fluid, omega is the oscillation frequency of the drop, DeltaV is the amplitude of volume oscillation, gamma is the equilibrium interfacial tension between the PDMS drop and water, and a is the radius of the capillary. A simplified model of a freely suspended spherical oscillating-drop well explains these observations. Viscous forces distort the drop shape at Ca>0.002, although this criterion is apparatus dependent.

  4. Multivariate bubbles and antibubbles

    Science.gov (United States)

    Fry, John

    2014-08-01

    In this paper we develop models for multivariate financial bubbles and antibubbles based on statistical physics. In particular, we extend a rich set of univariate models to higher dimensions. Changes in market regime can be explicitly shown to represent a phase transition from random to deterministic behaviour in prices. Moreover, our multivariate models are able to capture some of the contagious effects that occur during such episodes. We are able to show that declining lending quality helped fuel a bubble in the US stock market prior to 2008. Further, our approach offers interesting insights into the spatial development of UK house prices.

  5. Does monetary policy generate asset price bubbles ?

    OpenAIRE

    Blot, Christophe; Hubert, Paul; Labondance, Fabien

    2017-01-01

    This paper empirically assesses the effect of monetary policy on asset price bubbles and aims to disentangle the competing predictions of theoretical bubble models. First, we take advantage of the model averaging feature of Principal Component Analysis to estimate bubble indicators, for the stock, bond and housing markets in the United States and Euro area, based on the structural, econometric and statistical approaches proposed in the literature to measure bubbles. Second, we ...

  6. Neurological Adverse Effects in Patients of Advanced Colorectal Carcinoma Treated with Different Schedules of FOLFOX

    Directory of Open Access Journals (Sweden)

    Nusrat Bano

    2013-01-01

    Full Text Available The study is designed to assess the frequency and severity of few dose limiting neurological adverse effects of four different schedules of FOLFOX. Patients with histologically confirmed advanced colorectal carcinoma (CRC were included in the study. Toxicity was graded according to CTC v 2.0. The frequency of grade 3 and 4 adverse effects was comparatively assessed in each treatment arm. The difference in the pattern of toxicity between the treatment schedule was evaluated. The most frequent adverse symptom of neurological adverse effect was grade 1 paresthesia in the patients treated with FOLFOX4 schedule. Grade 4 peripheral neuropathy was reported in few patients of FOLFOX7 treatment arm. Frequency and onset of neurological adverse effects like paresthesia, dizziness, and hypoesthesia were significantly different (, whereas frequency and onset of peripheral neuropathy were highly significant ( in each treatment arm of FOLFOX. Peripheral neuropathy was associated with electrolyte imbalance and diabetes in few patients. Frequency of symptoms, for example, paresthesia, is associated with increased number of recurrent exposure to oxaliplatin (increased number of cycles even at low doses (85 mg/m2, whereas severity of symptoms, for example, peripheral neuropathy, is associated with higher dose (130 mg/m2 after few treatment cycles.

  7. Tunneling effects in resonant acoustic scattering of an air bubble in unbounded water

    Directory of Open Access Journals (Sweden)

    ANDRÉ G. SIMÃO

    2016-06-01

    Full Text Available Abstract The problem of acoustic scattering of a gaseous spherical bubble immersed within unbounded liquid surrounding is considered in this work. The theory of partial wave expansion related to this problem is revisited. A physical model based on the analogy between acoustic scattering and potential scattering in quantum mechanics is proposed to describe and interpret the acoustical natural oscillation modes of the bubble, namely, the resonances. In this context, a physical model is devised in order to describe the air water interface and the implications of the high density contrast on the various regimes of the scattering resonances. The main results are presented in terms of resonance lifetime periods and quality factors. The explicit numerical calculations are undertaken through an asymptotic analysis considering typical bubble dimensions and underwater sound wavelengths. It is shown that the resonance periods are scaled according to the Minnaert’s period, which is the short lived resonance mode, called breathing mode of the bubble. As expected, resonances with longer lifetimes lead to impressive cavity quality Q-factor ranging from 1010 to 105. The present theoretical findings lead to a better understanding of the energy storage mechanism in a bubbly medium.

  8. Vapor Bubbles in Flow and Acoustic Fields

    NARCIS (Netherlands)

    Prosperetti, Andrea; Hao, Yue; Sadhal, S.S

    2002-01-01

    A review of several aspects of the interaction of bubbles with acoustic and flow fields is presented. The focus of the paper is on bubbles in hot liquids, in which the bubble contains mostly vapor, with little or no permanent gas. The topics covered include the effect of translation on condensation

  9. Mechanics of gas-vapor bubbles

    NARCIS (Netherlands)

    Hao, Yue; Zhang, Yuhang; Prosperetti, Andrea

    2017-01-01

    Most bubbles contain a mixture of vapor and incondensible gases. While the limit cases of pure vapor and pure gas bubbles are well studied, much less is known about the more realistic case of a mixture. The bubble contents continuously change due to the combined effects of evaporation and

  10. A Review of Epidemiological Research on Adverse Neurological Effects of Exposure to Ambient Air Pollution

    Science.gov (United States)

    Xu, Xiaohui; Ha, Sandie Uyen; Basnet, Rakshya

    2016-01-01

    There is a growing body of epidemiological research reporting the neurological effects of ambient air pollution. We examined current evidence, identified the strengths and weaknesses of published epidemiological studies, and suggest future directions for research in this area. Studies were identified through a systematic search of online scientific databases, in addition to a manual search of the reference lists from the identified papers. Despite being a relatively new area of investigation, overall, there is mounting evidence implicating adverse effects of air pollution on neurobehavioral function in both adults and children. Further research is needed to expand our understanding of these relationships, including improvement in the accuracy of exposure assessments; focusing on specific toxicants and their relationships to specific health endpoints, such as neurodevelopmental disorders and neurodegenerative diseases; investigating the combined neurological effects of multiple air pollutants; and further exploration of genetic susceptibility for neurotoxicity of air pollution. In order to achieve these goals collaborative efforts are needed from multidisciplinary teams, including experts in toxicology, biostatistics, geographical science, epidemiology, and neurology. PMID:27547751

  11. The Effects of Helium Bubble Microstructure on Ductility in Annealed and HERF 21Cr-6Ni-9Mn Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Tosten, M.H. [Westinghouse Savannah River Company, AIKEN, SC (United States); Morgan, M.J.

    1998-01-01

    This study examined the effects of microstructure on the ambient temperature embrittlement from hydrogen isotopes and decay helium in 21Cr-6Ni-9Mn stainless steel. Hydrogen and tritium-exposed 21Cr-6Ni-9Mn stainless steel tensile samples were pulled to failure and then characterized by transmission electron microscopy (TEM) and optical microscopy. This study determined that ductility differences between annealed and high-energy-rate-forged (HERF) stainless steel containing tritium and its decay product, helium, could be related to differences in the helium bubble microstructures. The HERF microstructures were more resistant to tritium-induced embrittlement than annealed microstructures because the high number density of helium bubbles on dislocations trap tritium within the matrix and away from the grain boundaries.

  12. Effect of decompression-induced bubble formation on highly trained divers microvascular function.

    Science.gov (United States)

    Lambrechts, Kate; Pontier, Jean-Michel; Mazur, Aleksandra; Buzzacott, Peter; Morin, Jean; Wang, Qiong; Theron, Michael; Guerrero, Francois

    2013-11-01

    We previously showed microvascular alteration of both endothelium-dependent and -independent reactivity after a single SCUBA dive. We aimed to study mechanisms involved in this postdive vascular dysfunction. Ten divers each completed three protocols: (1) a SCUBA dive at 400 kPa for 30 min; (2) a 41-min duration of seawater surface head immersed finning exercise to determine the effect of immersion and moderate physical activity; and (3) a simulated 41-min dive breathing 100% oxygen (hyperbaric oxygen [HBO]) at 170 kPa in order to analyze the effect of diving-induced hyperoxia. Bubble grades were monitored with Doppler. Cutaneous microvascular function was assessed by laser Doppler. Endothelium-dependent (acetylcholine, ACh) and -independent (sodium nitroprusside, SNP) reactivity was tested by iontophoresis. Endothelial cell activation was quantified by plasma Von Willebrand factor and nitric oxide (NO). Inactivation of NO by oxidative stress was assessed by plasma nitrotyrosine. Platelet factor 4 (PF4) was assessed in order to determine platelet aggregation. Blood was also analyzed for measurement of platelet count. Cutaneous vascular conductance (CVC) response to ACh delivery was not significantly decreased by the SCUBA protocol (23 ± 9% before vs. 17 ± 7% after; P = 0.122), whereas CVC response to SNP stimulation decreased significantly (23 ± 6% before vs. 10 ± 1% after; P = 0.039). The HBO and immersion protocols did not affect either endothelial-dependent or -independent function. The immersion protocol induced a significant increase in NO (0.07 ± 0.01 vs. 0.12 ± 0.02 μg/mL; P = 0.035). This study highlighted change in microvascular endothelial-independent but not -dependent function in highly trained divers after a single air dive. The results suggest that the effects of decompression on microvascular function may be modified by diving acclimatization.

  13. Effects of argon sparging rate, ultrasonic power, and frequency on multibubble sonoluminescence spectra and bubble dynamics in NaCl aqueous solutions.

    Science.gov (United States)

    Cairós, Carlos; Schneider, Julia; Pflieger, Rachel; Mettin, Robert

    2014-11-01

    The sonoluminescence spectra from acoustic cavitation in aqueous NaCl solutions are systematically studied in a large range of ultrasonic frequencies under variation of electrical power and argon sparging. At the same time, bubble dynamics are analysed by high-speed imaging. Sodium line and continuum emission are evaluated for acoustic driving at 34.5, 90, 150, 365, and 945kHz in the same reactor vessel. The results show that the ratio of sodium line to continuum emission can be shifted by the experimental parameters: an increase in the argon flow increases the ratio, while an increase in power leads to a decrease. At 945kHz, the sodium line is drastically reduced, while the continuum stays at elevated level. Bubble observations reveal a remarkable effect of argon in terms of bubble distribution and stability: larger bubbles of non-spherical shapes form and eject small daughter bubbles which in turn populate the whole liquid. As a consequence, the bubble interactions (splitting, merging) appear enhanced which supports a link between non-spherical bubble dynamics and sodium line emission. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Effect of weld thermal cycle on helium bubble formation in stainless steel

    Science.gov (United States)

    Kano, F.; Nakahigashi, S.; Nakamura, H.; Uesugi, N.; Mitamura, T.; Terasawa, M.; Irie, H.; Fukuya, K.

    1998-10-01

    Helium bubble structure was examined on a helium-implanted stainless steel after applying two kinds of heat input. Helium ions were implanted on Type 304 stainless steel at 573 K from 2 to 200 appm to a peak depth of 0.5 μm from the surface. After that, weld thermal history was applied by an electron beam. The cooling rates were selected to be 370 and 680 K/s from 1023 to 773 K. TEM observation revealed that nucleation and growth of helium bubbles were strongly dependent on the cooling rate after welding and the helium concentration.

  15. Turbulent hydraulic jumps: Effect of Weber number and Reynolds number on air entrainment and micro-bubble generation

    Science.gov (United States)

    Mortazavi, Milad; Mani, Ali

    2015-11-01

    Air entrainment in breaking waves is a ubiquitous and complex phenomenon. It is the main source of air transfer from atmosphere to the oceans. Furthermore, air entrainment due to ship-induced waves contributes to bubbly flows in ship wakes and also affect their performance. In this study, we consider a turbulent hydraulic jump as a canonical setting to investigate air entrainment due to turbulence-wave interactions. The flow has an inlet Froude number of 2.0, while three different Weber numbers (We = 1820, 729, 292), and two different Reynolds numbers (Re = 11000, 5500) based on the inlet height and inlet velocity are investigated. Air entrainment is shown to be very sensitive to the We number, while Re number has a minor effect. Wave breaking and interface collisions are significantly reduced in the low Weber number cases. As a result, micro-bubble generation is significantly reduced with decreasing Weber number. Vortex shedding events are observed to emerge at the toe of the jump in all of the cases. For high Weber number regimes, shedding of vortices is accompanied by engulfment of air pockets into the jump in a periodic manner, while for lower Webber number regimes such events are significantly suppressed. Reynolds number is shown to have a negligible effect on the air entrainment, wave breaking and micro-bubble generation, contrary to the previous assumptions in other studies. Supported by ONR.

  16. Pre-dive vibration effect on bubble formation after a 30-m dive requiring a decompression stop.

    Science.gov (United States)

    Germonpré, Peter; Pontier, Jean-Michel; Gempp, Emmanuel; Blatteau, Jean-Eric; Deneweth, Stefaan; Lafère, Pierre; Marroni, Alessandro; Balestra, Costantino

    2009-12-01

    The preconditioning of divers to reduce post-dive decompression sickness (DCS) has gained increased interest in diving medical research over the last few years. The beneficial effects of physical exercise, oxygen breathing, hyperbaric exposure, heat exposure, hyperhydration, or nitroglycerin administration before the dive are only a few examples of ongoing research. In this work, we investigated the effects of pre-dive whole-body vibration on post-dive bubble formation. Following French Navy standard dive procedures, 14 healthy male military divers performed 2 identical dives 1 wk apart to 30 m of seawater (msw) for 30 min. One of the dives was randomly preceded by a 30-min whole-body vibration session (frequencies 35-40 Hz) 1 h before the dive. Post-dive bubbles were measured precordially 30, 60, and 90 min after the dive and were graded according to the Kissman Integrated Severity Score (KISS) protocol, with and without knee flexing. Arterial endothelial function was measured before and after vibration using flow mediated dilation (FMD) measurement. A significant reduction in bubble scores was observed after the "vibration" dive. As there was no observed change in FMD after vibration, we do not believe a nitric oxide mediated mechanism is involved; rather, a mechanical dislodgement or enhanced lymphatic elimination of gas nuclei is hypothesized.

  17. Bubble dynamics in drinks

    Directory of Open Access Journals (Sweden)

    Broučková Zuzana

    2014-03-01

    Full Text Available This study introduces two physical effects known from beverages: the effect of sinking bubbles and the hot chocolate sound effect. The paper presents two simple „kitchen” experiments. The first and second effects are indicated by means of a flow visualization and microphone measurement, respectively. To quantify the second (acoustic effect, sound records are analyzed using time-frequency signal processing, and the obtained power spectra and spectrograms are discussed.

  18. Frictional drag reduction by bubble injection

    Science.gov (United States)

    Murai, Yuichi

    2014-07-01

    The injection of gas bubbles into a turbulent boundary layer of a liquid phase has multiple different impacts on the original flow structure. Frictional drag reduction is a phenomenon resulting from their combined effects. This explains why a number of different void-drag reduction relationships have been reported to date, while early works pursued a simple universal mechanism. In the last 15 years, a series of precisely designed experimentations has led to the conclusion that the frictional drag reduction by bubble injection has multiple manifestations dependent on bubble size and flow speed. The phenomena are classified into several regimes of two-phase interaction mechanisms. Each regime has inherent physics of bubbly liquid, highlighted by keywords such as bubbly mixture rheology, the spectral response of bubbles in turbulence, buoyancy-dominated bubble behavior, and gas cavity breakup. Among the regimes, bubbles in some selected situations lose the drag reduction effect owing to extra momentum transfer promoted by their active motions. This separates engineers into two communities: those studying small bubbles for high-speed flow applications and those studying large bubbles for low-speed flow applications. This article reviews the roles of bubbles in drag reduction, which have been revealed from fundamental studies of simplified flow geometries and from development of measurement techniques that resolve the inner layer structure of bubble-mixed turbulent boundary layers.

  19. Comparative analysis of the effects of hubble-bubble (Sheesha) and cigarette smoking on respiratory and metabolic parameters in hubble-bubble and cigarette smokers.

    Science.gov (United States)

    Al Mutairi, Sana S; Shihab-Eldeen, Aida A; Mojiminiyi, Olusegun A; Anwar, Alia Aisha

    2006-07-01

    Hazard of smoking tobacco is believed to be minimized by smoking hubble-bubble (HB) instead of cigarettes. Our aims were to (i) develop an assay for estimating nicotine and cotinine; and (ii) evaluate the effect of smoking on respiratory and metabolic parameters in cigarette and HB smokers. Urine samples were collected from 152 volunteer smokers (75 cigarette and 77 HB) as well as from 16 healthy controls. We optimized an HPLC method for the determination of nicotine and cotinine. Subjects were asked to complete a chronic respiratory symptoms questionnaire and to undergo spirometry. Fasting blood samples were collected for the determination of their lipid profile. The intra-assay coefficients of variation for nicotine and cotinine were 16.6% and 6.6%, respectively. The mean of cotinine in cigarette smokers (1321.4 ng/mL) was significantly (P = 0.008) higher than the mean cotinine (677.6 ng/mL) in HB smokers. The mean nicotine level in cigarette smokers (1487.3 ng/mL) was significantly (P < 0.0001) higher than the mean nicotine (440.5 ng/mL) in HB smoker. The urinary cotinine and nicotine levels of the control subjects were lower than the detection levels of the assay. The mean high-density lipoprotein cholesterol was lower in cigarette smokers (0.99 mmol/L) compared with HB smoker smokers (1.02 mmol/L) but this was not significant (P = 0.28). Spirometric values were comparable among the three groups but the chronic respiratory symptoms in the smoking groups appeared at an earlier age in the HB smokers compared with the cigarettes smokers (P < 0.05). Smoking HB does not reduce the risk of tobacco exposure and it's potentially harmful metabolites on health.

  20. Bubbles effect on sound dispersion in thin-walled tube with polymeric liquid and elastic central rod

    Science.gov (United States)

    Levitsky, S. P.; Bergman, R. M.; Haddad, J.

    2011-06-01

    The present study is devoted to the investigation of fine air bubbles effect on sound propagation in thin-walled elastic tube with compressible polymeric liquid and cylindrical elastic rod in the central part of the tube. The problem formulation and solution method follow the previous paper of the authors (S.P. Levitsky, R.M. Bergman, J. Haddad, Sound dispersion in deformable tube with polymeric liquid and elastic central rod, Journal of Sound and Vibration 275 (1-2) (2004) 267-281). In order to account for the bubbles' influence on sound dispersion and attenuation, dynamic equation of state of the mixture, formulated within homogeneous approximation, is used. It is assumed that the volume gas concentration is small. The resulting dispersion equation for the waveguide with viscoelastic liquid-gas mixture is studied in a long-wave range. Results of simulations illustrate the influence of free gas concentration, bubble radius and rheological properties of the liquid on sound dispersion and attenuation in the system.

  1. Optical observations of acoustical radiation force effects on individual air bubbles

    NARCIS (Netherlands)

    Palanchon, Peggy; Tortoli, Piero; Bouakaz, Ayache; Versluis, Michel; de Jong, N.

    2005-01-01

    Previous studies dealing with contrast agent microbubbles have demonstrated that ultrasound (US) can significantly influence the movement of microbubbles. In this paper, we investigated the influence of the acoustic radiation force on individual air bubbles using high-speed photography. We emphasize

  2. Bubble bath soap poisoning

    Science.gov (United States)

    ... medlineplus.gov/ency/article/002762.htm Bubble bath soap poisoning To use the sharing features on this page, please enable JavaScript. Bubble bath soap poisoning occurs when someone swallows bubble bath soap. ...

  3. The effect of exercise and rest duration on the generation of venous gas bubbles at altitude

    Science.gov (United States)

    Dervay, Joseph P.; Powell, Michael R.; Butler, Bruce; Fife, Caroline E.

    2002-01-01

    BACKGROUND: Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause gas bubbles to form within the organism. Pressure changes to evoke bubble formation in vivo during depressurization are several orders of magnitude less than those required for gas phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue gas micronuclei have been attributed to a minute gas phase located in hydrophobic cavities, surfactant-stabilized microbubbles, or arising from musculoskeletal activity. The lifetimes of these micronuclei have been presumed to be from a few minutes to several weeks. HYPOTHESIS: The greatest incidence of venous gas emboli (VGE) will be detected by precordial Doppler ultrasound with depressurization immediately following lower extremity exercise, with progressively reduced levels of VGE observed as the interval from exercise to depressurization lengthens. METHODS: In a blinded cross-over design, 20 individuals (15 men, 5 women) at sea level exercised by performing knee-bend squats (150 knee flexes over 10 min, 235-kcal x h(-1)) either at the beginning, middle, or end of a 2-h chair-rest period without an oxygen prebreathe. Seated subjects were then depressurized to 6.2 psia (6,706 m or 22,000 ft altitude equivalent) for 120 min with no exercise performed at altitude. RESULTS: Of the 20 subjects with VGE in the pulmonary artery, 10 demonstrated a greater incidence of bubbles with exercise performed just prior to depressurization, compared with decreasing bubble grades and incidence as the interval of rest increased prior to depressurization. No decompression illness was reported. CONCLUSIONS: There is a significant increase in decompression-induced bubble formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals

  4. Robust acoustic wave manipulation of bubbly liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gumerov, N. A., E-mail: gumerov@umiacs.umd.edu [Institute for Advanced Computer Studies, University of Maryland, College Park, Maryland 20742 (United States); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Akhatov, I. S. [Center for Design, Manufacturing and Materials, Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Ohl, C.-D. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Sametov, S. P. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Khazimullin, M. V. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Institute of Molecule and Crystal Physics, Ufa Research Center of Russian Academy of Sciences, Ufa 450054 (Russian Federation); Gonzalez-Avila, S. R. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2016-03-28

    Experiments with water–air bubbly liquids when exposed to acoustic fields of frequency ∼100 kHz and intensity below the cavitation threshold demonstrate that bubbles ∼30 μm in diameter can be “pushed” away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.

  5. A note on the dynamics of two aligned bubbles perpendicular to and above a thin membrane

    Energy Technology Data Exchange (ETDEWEB)

    Aghdam, A Hajizadeh [Department of Mechanical Engineering, Arak University of Technology, Arak 3818141167 (Iran, Islamic Republic of); Khoo, B C, E-mail: Hajizadeh@arakut.ac.ir [Department of Mechanical Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)

    2015-06-15

    The interaction of two perpendicular bubbles of a similar size (upper bubble and lower bubble) and the thin elastic membrane beneath them is studied experimentally. The dynamical behavior of the lower bubble (Bubble1), which is placed between the membrane and upper bubble (Bubble2), is rather complex. Observed phenomena such as the splitting of Bubble1 into the ‘mushroom shape’ and ‘masher shape’, the bubble-collapse induced jetting toward Bubble2 and even the coalescence effect are found and systematically categorized by the stated dimensionless parameters. (paper)

  6. Metoclopramide neurological side effects screening; a pharmacovigilence study in Romanian community pharmacies

    Directory of Open Access Journals (Sweden)

    Emil Ștefănescu

    2015-04-01

    Full Text Available Background. Metoclopramide is a pharmacological agent frequently used in therapy against nausea and vomiting that can occur in indigestion, motion sickness, gastric ulcer, pyloric spasm and after surgery as a side effect of some anesthetics. Knowing the frequency and intensity of metoclopramide neurological side effects is essential for an efficient management of the dysfunctions it addresses. Material and method. Based on a standard questionnaire containing questions regarding metoclopramide therapy, we analyzed the answers given by 1000 patients or patient tutors in 20 open circuit pharmacies situated all over Bucharest. All subjects freely consented to participate in this study that was coordinated only by pharmacists. Results. Our study highlights the fact that in certain situations having to do with the age of patients, with the use of multiple drugs or with the tendency to self medicate, the neurological side effects of metoclopramide can reach dangerous levels. In some cases it might even be necessary to immediately interrupt metoclopramide therapy, despite its positive benefit/ risk ratio. Conclusions. Respecting the physician’s recommendations, avoiding self medication and reporting side effects as quickly as possible, are essential elements for minimizing the consequences of metoclopramide side effects.

  7. Scaling regimes of thermocapillarity-driven dynamics of confined long bubbles: Effects of disjoining pressure

    Science.gov (United States)

    Chaudhury, Kaustav; Chakraborty, Suman

    2015-03-01

    During thermocapillary transport of a confined long bubble, we unveil the existence of a contrary-to-the-conventional disjoining-pressure-dominant scaling regime characterizing the dynamics of the thin liquid film engulfed between the bubble interface and the channel surface. Such a regime is realized for the limitingly small magnitude of the Marangoni stress (surface tension gradient) when the separating liquid region reaches an ultrathin dimension. Over this regime, we witness a severe breakdown of the seemingly intuitive scaling arguments based on the balance of viscous and capillary forces. Starting from competent balance criteria, we uncover the characteristic length scales involved, leading towards obtaining the new consistent scaling laws of the disjoining-pressure-dominant regime, in a simple closed form analytical fashion. Our scaling estimations are substantiated by full-scale numerical simulations of the pertinent thin-film equations. These new scaling laws appear to be convenient for implementing as a fundamental design basis for multiphase microfluidic systems.

  8. Effect of surface mobility on the uniformity of a thin film under a bubble.

    Science.gov (United States)

    Berteloot, G; Sharif-Kashani, P; Kavehpour, H P

    2011-12-20

    The shape of a soap bubble placed on a solid surface is familiar to everyone-a thin hemispherical dome that thickens near the solid surface. This structure is stabilized by the balance between the film's elasticity, provided by surfactant molecules, and the pressure inside the bubble. However, there is also a soap film on the flat solid surface that has been mostly ignored in previous studies; its thickness is typically assumed to be constant or varying monotonically. In this letter, for the first time, we show that the thickness of this film is not always monotonic. Depending on the surfactant type, it can exhibit a significant dip, similar to marginal pinching. This finding has a significant influence in numerous applications in which solid/foam interactions are important, such as oil extraction or foam-based drug delivery. © 2011 American Chemical Society

  9. The Pathophysiology of Decompression Sickness and the Effects of Doppler Detectable Bubbles.

    Science.gov (United States)

    1980-12-18

    arterial bubbles could be associated with visual and other central nervous system problems, the mechanism of trans- pulmonic passage needs further...the capillaries being congested. Edema was not noted, however, in dogs which died suddenly. They concluded that small amounts of injected air produced...pulmonary edema and die or develop bronchial pneumonia and die from otherwise non-fatal pulmonary edema . Furthermore, animals which hyperventilated well

  10. Viscoelasticity of liquid organic foam: Relaxations, temporal dependence, and bubble loading effects on flow behavior

    Science.gov (United States)

    Kropka, Jamie M.; Celina, Mathew

    2010-07-01

    Liquid organic foams are prepared using a new blowing process based on the chemical generation of carbon dioxide. The foams are volumetrically stable for periods up to hours and can be fabricated with gas volume fractions ranging from 0.10 to 0.95. Both the "fresh" and temporal dependences of the linear viscoelastic response of these materials are evaluated. The organic foams exhibit rheological behavior characteristic of their aqueous counterparts: a weak dependence of the shear moduli over an extended frequency/time regime that is bounded by both a fast and slow relaxation. The onset of the fast mechanical response of the organic foams occurs at approximately the same frequency as in aqueous foams despite the continuous phase viscosity differing by orders of magnitude between the systems. This suggests that the viscosity does not affect the time scale of the "anomalous" viscous loss characteristic of these materials, which challenges currently proposed mechanisms for this dissipation and leaves the origin of the loss behavior unclear. The relative contribution of cell growth and bubble motion to the slow relaxation is also discerned by evaluating the relation between the transient and dynamic responses of the foam. Finally, the development of elasticity in the foam due to bubble interactions is analyzed and a bubble slip process is postulated to account for the lack of a true elastic response of the foam at intermediate time scales (between the fast and slow mechanical response) when gas fractions exceed 0.64.

  11. Simulations of Rising Hydrodynamic and Magnetohydrodynamic Bubbles

    Science.gov (United States)

    Ricker, P. M.; Robinson, K.; Dursi, L. J.; Rosner, R.; Calder, A. C.; Zingale, M.; Truran, J. W.; Linde, T.; Caceres, A.; Fryxell, B.; Olson, K.; Riley, K.; Siegel, A.; Vladimirova, N.

    Motivated by recent Chandra and XMM-Newton observations of X-ray emission voids in galaxy cluster cooling flows, we have investigated the behavior of rising bubbles in stratified atmospheres using the FLASH adaptive-mesh simulation code. We present results from two-dimensional simulations with and without the effects of magnetic fields, and with varying bubble sizes and background stratifications. We find purely hydrodynamic bubbles to be unstable; a dynamically important magnetic field is required to maintain a bubble's integrity. This suggests that, even absent thermal conduction, for bubbles to be persistent enough to be regularly observed, they must be supported in large part by magnetic fields. We also observe that magnetically supported bubbles leave a tail as they rise. The structure of these tails may provide clues to the bubble's dynamical history.

  12. Retrospective study of the clinical effects of acupuncture on cervical neurological diseases in dogs.

    Science.gov (United States)

    Liu, Ching Ming; Chang, Fang Chia; Lin, Chung Tien

    2016-09-30

    This study was conducted to evaluate new acupuncture protocols for the clinical treatment of cervical spinal cord diseases in 19 dogs. Three treatment options containing Jing-jiaji (cervical jiaji) were developed to treat neck pain, hemiparesis, and tetraparesis depending on the severity. The interval between the neurological disease onset and treatment (duration of signs), time to improvement after treatment, and recovery time were compared in dogs by body weight, age, and dry needle acupuncture (AP) with or without electro-AP (EAP). The duration of signs was longer in dogs weighing greater than 10 kg than in those weighing less than 10 kg (p< 0.05). Improvement and recovery times did not vary by body weight. Additionally, improvement and recovery times did not vary by age. The improvement and recovery times were longer in the AP+EAP group than the AP group (p< 0.05). Acupuncture with Jing-jiaji was effective in cervical spinal cord diseases in different sized dogs and in middle-aged and senior dogs. This report standardized AP treatment containing Jing-jiaji for canine cervical problems and evaluated its effects. The newly standardized AP methodology offers clinical practitioners an effective way to improve the outcomes of cervical neurological diseases in dogs.

  13. Effects of ammonium bicarbonate on the electrospray mass spectra of proteins: evidence for bubble-induced unfolding.

    Science.gov (United States)

    Hedges, Jason B; Vahidi, Siavash; Yue, Xuanfeng; Konermann, Lars

    2013-07-02

    Many protein investigations by electrospray ionization (ESI) mass spectrometry (MS) strive to ensure a "native" solvent environment, i.e., nondenaturing conditions up to the point of gas-phase ion formation. Ideally, these studies would employ a volatile pH buffer to mitigate changes in H(+) concentration that can occur during ESI. Ammonium acetate is a commonly used additive, despite its low buffering capacity at pH 7. Ammonium bicarbonate provides greatly improved pH stabilization, thus offering an interesting alternative. Surprisingly, protein analyses in bicarbonate at pH 7 tend to result in the formation of very high charge states, similar to those obtained when electrospraying unfolded proteins in a denaturing solvent. This effect has been reported previously (Sterling, H. J.; Cassou, C. A.; Susa, A. C.; Williams, E. R. Anal. Chem. 2012, 84, 3795), but its exact mechanistic origin remains unclear. ESI-mediated unfolding does not take place in acetate under otherwise identical conditions. We demonstrate that heating of protein-containing bicarbonate solutions results in extensive foaming, caused by CO2 outgassing. In contrast, acetate solutions do not generate foam. Protein denaturation caused by gas bubbles is a well-known phenomenon. Adsorption to the gas/liquid interface is accompanied by major conformational changes that allow the protein to act as a surfactant. The foaming of beer is a manifestation of this effect. Bubble formation in bicarbonate during ESI is facilitated by collisional and blackbody droplet heating. Our data imply that heat and bubbles act synergistically to cause unfolding during the electrospray process, while proteins reside in ESI droplets. Because of this effect we advise against the use of ammonium bicarbonate for native ESI-MS. Ammonium acetate represents a gentler droplet environment, despite its low buffering capacity.

  14. Effects of mTOR on neurological deficits after transient global ischemia

    Directory of Open Access Journals (Sweden)

    Xing Jihong

    2017-04-01

    Full Text Available Mammalian target of rapamycin (mTOR is a serine/threonine protein kinase and activation of its signal pathway plays an important role in regulating protein growth and synthesis as well as cell proliferation and survival. In the present study, we examined the contribution of mTOR and its downstream products to brain injuries and neurological deficiencies after cardiac arrest (CA induced-transient global ischemia. CA was induced by asphyxia followed by cardiopulmonary resuscitation (CPR in rats. Our results showed that expression of p-mTOR, mTOR-mediated phosphorylation of 4E-binding protein 4 (4E-BP1 and p70 ribosomal S6 protein kinase 1 (S6K1 pathways were amplified in CA rats compared to their controls. Blocking mTOR using rapamycin attenuated upregulation of pro-inflammatory cytokines (namely IL-1β, IL-6 and TNF-α, and Caspase-3, indicating cell apoptosis and also promoting the levels of vascular endothelial growth factor (VEGF and its subtype receptor VEGFR-2 in the hippocampus. Moreover, the effects of rapamycin were linked to improvement of neurological deficits and increased brain water content observed in CA rats. In conclusion, activation of mTOR signal is engaged in pathophysiological process during CA-induced transient global ischemia and blocking mTOR pathway plays a beneficial role in regulating injured neuronal tissues and neurological deficits via PIC, apoptotic Caspase-3 and VEGF mechanisms. Targeting one or more of these specific mTOR pathways and its downstream signaling molecules may present new opportunities for neural dysfunction and vulnerability related to transient global ischemia.

  15. Effectiveness of music-based interventions on motricity or cognitive functioning in neurological populations: a systematic review.

    OpenAIRE

    Moumdjian, Lousin; Sarkamo, Teppo; Leone, Carmela; Leman, Marc; Feys, Peter

    2016-01-01

    INTRODUCTION: Motor and cognitive symptoms are frequent in persons with neurological disorders and often require extensive long-term rehabilitation. Recently, a variety of musicbased interventions have been introduced into neurological rehabilitation as training tools. AIM: This review aims to a) describe and define music-based intervention modalities and content which are applied in experimental studies, and b) describe the effects of these interventions on motor and/or cognitive symptoms...

  16. Lattice Boltzmann Simulation of Multiple Bubbles Motion under Gravity

    Directory of Open Access Journals (Sweden)

    Deming Nie

    2015-01-01

    Full Text Available The motion of multiple bubbles under gravity in two dimensions is numerically studied through the lattice Boltzmann method for the Eotvos number ranging from 1 to 12. Two kinds of initial arrangement are taken into account: vertical and horizontal arrangement. In both cases the effects of Eotvos number on the bubble coalescence and rising velocity are investigated. For the vertical arrangement, it has been found that the coalescence pattern is similar. The first coalescence always takes place between the two uppermost bubbles. And the last coalescence always takes place between the coalesced bubble and the bottommost bubble. For four bubbles in a horizontal arrangement, the outermost bubbles travel into the wake of the middle bubbles in all cases, which allows the bubbles to coalesce. The coalescence pattern is more complex for the case of eight bubbles, which strongly depends on the Eotvos number.

  17. Cerebrolysin effects on neurological outcomes and cerebral blood flow in acute ischemic stroke

    Directory of Open Access Journals (Sweden)

    Amiri-Nikpour MR

    2014-12-01

    Full Text Available Mohammad Reza Amiri-Nikpour,1 Surena Nazarbaghi,1 Babak Ahmadi-Salmasi,1 Tayebeh Mokari,2 Urya Tahamtan,2 Yousef Rezaei3 1Department of Neurology, Imam Khomeini Hospital, 2School of Medicine, 3Seyyed-al-Shohada Heart Center, Urmia University of Medical Sciences, Urmia, Iran Background: Cerebrolysin, a brain-derived neuropeptide, has been shown to improve the neurological outcomes of stroke, but no study has demonstrated its effect on cerebral blood flow. This study aimed to determine the cerebrolysin impact on the neurological outcomes and cerebral blood flow. Methods: In a randomized, double-blinded, placebo-controlled trial, 46 patients who had acute focal ischemic stroke were randomly assigned into two groups to receive intravenously either 30 mL of cerebrolysin diluted in normal saline daily for 10 days (n=23 or normal saline alone (n=23 adjunct to 100 mg of aspirin daily. All patients were examined using the National Institutes of Health Stroke Scale and transcranial Doppler to measure the mean flow velocity and pulsatility index (PI of their cerebral arteries at baseline as well as on days 30, 60, and 90. Results: The patients’ mean age was 60±9.7 years, and 51.2% of patients were male. The National Institutes of Health Stroke Scale was significantly lower in the cerebrolysin group compared with the placebo group on day 60 (median 10, interquartile range 9–11, P=0.008 and day 90 (median 11, interquartile range 10–13.5, P=0.001. The median of PI in the right middle cerebral artery was significantly lower in the cerebrolysin group compared with the placebo group on days 30, 60, and 90 (P<0.05. One patient in the cerebrolysin group and two patients in the placebo group died before day 30 (4.3% versus 8.7%. Conclusion: Cerebrolysin can be useful to improve the neurological outcomes and the PI of middle cerebral artery in patients with acute focal ischemic stroke. Keywords: ischemic stroke, cerebrolysin, neuroprotection, NIHSS, mean

  18. Fama on bubbles

    DEFF Research Database (Denmark)

    Engsted, Tom

    Eugene Fama has repeatedly expressed his discontent with the notion of an irrational bubble. However, he has never publicly expressed his opinion on rational bubbles. This is peculiar since such bubbles build naturally from the rational efficient markets paradigm that Fama strongly adheres to. On......, there is evidence of an explosive component in stock market valuation ratios, consistent with a rational bubble........ On empirical grounds Fama rejects bubbles by referring to the lack of reliable evidence that price declines are predictable. However, this argument cannot be used to rule out rational bubbles because such bubbles do not necessarily imply return predictability. On data samples that include the 1990s...

  19. Genetics of neurological disorders.

    Science.gov (United States)

    Faghihi, Mohammad Ali; Mottagui-Tabar, Salim; Wahlestedt, Claes

    2004-05-01

    Neurological diseases are defined as an inappropriate function of the peripheral or central nervous system due to impaired electrical impulses throughout the brain and/or nervous system that may present with heterogeneous symptoms according to the parts of the system involved in these pathologic processes. Growing evidence on genetic components of neurological disease have been collected during recent years. Genetic studies have opened the way for understanding the underlying pathology of many neurological disorders. The outcome of current intense research into the genetics of neurological disorders will hopefully be the introduction of new diagnostic tools and the discovery of potential targets for new and more effective medications and preventive measures.

  20. Effectiveness of Music Therapy as an aid to Neurorestoration of children with severe neurological disorders

    Directory of Open Access Journals (Sweden)

    Maria L Bringas

    2015-11-01

    Full Text Available This study was a two-armed parallel group design aimed at testing real world effectiveness of a music therapy (MT intervention for children with severe neurological disorders. The control group received only the standard neurorestoration program and the experimental group received an additional MT Auditory Attention plus Communication (ACC protocol just before the usual occupational and speech therapy. Multivariate Item Response Theory (MIRT identified a neuropsychological status-latent variable manifested in all children and which exhibited highly significant changes only in the experimental group. Changes in brain plasticity also occurred in the experimental group, as evidenced using a Mismatch Event Related paradigm which revealed significant post intervention positive responses in the latency range between 308 and 400 ms in frontal regions. LORETA EEG source analysis identified prefrontal and midcingulate regions as differentially activated by the MT in the experimental group. Taken together, our results showing improved attention and communication as well as changes in brain plasticity in children with severe neurological impairments, highlight/comfort the importance of MT for the rehabilitation of patients across a wide range of dysfunctions.

  1. Effect of bubble size and density on methane conversion to hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Leske, J.; Taylor, C.E.; Ladner, E.P.

    2007-03-01

    Research is underway at NETL to understand the physical properties of methane hydrates. One area of investigation is the storage of methane as methane hydrates. An economical and efficient means of storing methane in hydrates opens many commercial opportunities such as transport of stranded gas, off-peak storage of line gas, etc.We have observed during our investigations that the ability to convert methane to methane hydrate is enhanced by foaming of the methane–water solution using a surfactant. The density of the foam, along with the bubble size, is important in the conversion of methane to methane hydrate.

  2. Hippotherapy effects on trunk, pelvic, and hip motion during ambulation in children with neurological impairments.

    Science.gov (United States)

    Encheff, Jenna L; Armstrong, Charles; Masterson, Michelle; Fox, Christine; Gribble, Phillip

    2012-01-01

    This study investigated the effects of a 10-week hippotherapy program on trunk, pelvis, and hip joint positioning during the stance phase of gait. Eleven children (6 boys and 5 girls; 7.9 ± 2.7 years) with neurological disorders and impaired ambulation participated. Joint range of motion data were collected via 3-dimensional computerized gait analysis before and after the program. Paired t tests were performed on kinematic data for each joint. Significant improvements (P ≤ .008) and large effect sizes (ESs) for sagittal plane hip positions at initial contact and toe-off were found. No differences in pelvic or trunk positioning were determined, although sagittal plane pelvic positioning displayed a trend toward improvement with large ESs. Several trunk variables displayed moderate ESs with a trend toward more upright positioning. Improvements in pelvic and hip joint positioning and more normalized vertical trunk position may indicate increased postural control during gait after 10 sessions of hippotherapy.

  3. Meshless bubble filter using ultrasound for extracorporeal circulation and its effect on blood.

    Science.gov (United States)

    Mino, Koji; Imura, Masato; Koyama, Daisuke; Omori, Masayoshi; Kawarabata, Shigeki; Sato, Masafumi; Watanabe, Yoshiaki

    2015-02-01

    A bubble filter with no mesh structure for extracorporeal circulation using ultrasound was developed. Hemolysis was evaluated by measuring free hemoglobin (FHb). FHb in 120 mL of bovine blood was measured in acoustic standing-wave fields. With a sound pressure amplitude of 60 kPa at driving frequencies of 1 MHz, 500 kHz and 27 kHz for 15 min. FHb values were 641.6, 2575 and 8903 mg/dL, respectively. Thus, hemolysis was inhibited with higher driving frequencies when the same sound pressure amplitude was applied. An ultrasound bubble filter with a resonance frequency of 1 MHz was designed. The filtering characteristics of the flowing microbubbles were investigated with a circulation system using bovine blood with a flow rate of 5.0 L/min. Approximately 99.1% of microbubbles were filtered with 250 kPa and a flow of 5.0 L/min. Hemolysis decreased as the sound pressure decreased; FHb values were 225.8 and 490.7 mg/dL when using 150 and 200 kPa, respectively. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  4. Liquid jet formation through the interactions of a laser-induced bubble and a gas bubble

    Science.gov (United States)

    Han, Bing; Liu, Liu; Zhao, Xiong-Tao; Ni, Xiao-Wu

    2017-10-01

    The mechanisms of the liquid jet formation from the interaction of the laser-induced and gas bubble pair are investigated and compared with the jet formation from the interaction of the laser-induced anti-phase bubble pair. The strobe photography experimental method and numerical simulations are implemented to obtain the parameter space of the optimum liquid jet, i.e. highest speed and lowest diameter. It is found that due to the enhanced "catapult effect", which is induced by the protrusion of the first bubble into the second bubble and the flip back of the elongated part of the first bubble, the optimum liquid jet of the second bubble of the laser-induced anti-phase bubble pair compared to that of the laser-induced and gas bubble pair is 54 %, 65 % and 11 % faster in speed, and 4 %, 44 % and 64 % smaller in diameter, for the 500 μm, 50 μm and 5 μm sized bubbles, respectively. The optimum dimensionless distance for the optimum jet of the laser-induced and the gas bubble is around 0.7, when the maximum bubble radius increases from ˜ 5μm to ˜500 μm, which is different from the laser-induced anti-phase bubble pairs. Besides, the optimum jet of the laser-induced bubble appeared when the bubbles are equal sized, while that of the gas bubble is independent of the relative bubble size, i.e. the liquid jet of the gas bubble has higher robustness in real liquid jet assisted applications when the laser-induced bubble size varies. However, the jet of bubble 2 could maintain a high speed (20 m/s - 35 m/s) and a low diameter (˜5 % of the maximum bubble diameter) over a big range of the dimensionless distance (0.6 - 0.9) for both of the 50 μm and 500 μm sized laser-induced equal sized anti-phase bubble pairs.

  5. Soap bubbles in paintings: Art and science

    Science.gov (United States)

    Behroozi, F.

    2008-12-01

    Soap bubbles became popular in 17th century paintings and prints primarily as a metaphor for the impermanence and fragility of life. The Dancing Couple (1663) by the Dutch painter Jan Steen is a good example which, among many other symbols, shows a young boy blowing soap bubbles. In the 18th century the French painter Jean-Simeon Chardin used soap bubbles not only as metaphor but also to express a sense of play and wonder. In his most famous painting, Soap Bubbles (1733/1734) a translucent and quavering soap bubble takes center stage. Chardin's contemporary Charles Van Loo painted his Soap Bubbles (1764) after seeing Chardin's work. In both paintings the soap bubbles have a hint of color and show two bright reflection spots. We discuss the physics involved and explain how keenly the painters have observed the interaction of light and soap bubbles. We show that the two reflection spots on the soap bubbles are images of the light source, one real and one virtual, formed by the curved surface of the bubble. The faint colors are due to thin film interference effects.

  6. The effect of positively chirped laser pulse on energy enhancement of proton acceleration in combinational radiation pressure and bubble regime

    Science.gov (United States)

    Vosoughian, H.; Sarri, G.; Borghesi, M.; Hajiesmaeilbaigi, F.; Afarideh, H.

    2017-10-01

    Proton energy enhancement in a combinational radiation pressure and bubble regime by applying a positively chirped laser pulse has been studied using a series of two-dimensional particle-in-cell simulations. In this regime, the proton injection in the half-first period of an excited plasma wave in an under-dense plasma plays the main role in the acceleration process. Moreover, exciting as high as large-amplitude plasma waves can significantly increase the conversion efficiency of laser energy into kinetic energy of the trapped protons. Here, the utilization of the positively chirped laser pulse is proposed as an effective approach to excite the higher amplitude wake in the combinational regime. Our studies indicate that in the positively chirped combinational regime, the plasma wake with approximately two-fold enhancement is produced that results in the generation of the proton bunch with the narrower energy spread and also the peak enhancement by a factor of two, compared with the un-chirped one. This improvement in proton energy reveals that the chirped laser pulse can be introduced as a tool to tune the energy of generated protons in the combinational radiation pressure and bubble regime.

  7. Bubbles and foams in microfluidics.

    Science.gov (United States)

    Huerre, Axel; Miralles, Vincent; Jullien, Marie-Caroline

    2014-09-28

    Microfluidics offers great tools to produce highly-controlled dispersions of gas into liquid, from isolated bubbles to organized microfoams. Potential technological applications are manifold, from novel materials to scaffolds for tissue engineering or enhanced oil recovery. More fundamentally, microfluidics makes it possible to investigate the physics of complex systems such as foams at scales where the capillary forces become dominant, in model experiments involving few well-controlled parameters. In this context, this review does not have the ambition to detail in a comprehensive manner all the techniques and applications involving bubbles and foams in microfluidics. Rather, it focuses on particular consequences of working at the microscale, under confinement, and hopes to provide insight into the physics of such systems. The first part of this work focuses on bubbles, and more precisely on (i) bubble generation, where the confinement can suppress capillary instabilities while inertial effects may play a role, and (ii) bubble dynamics, paying special attention to the lubrication film between bubble and wall and the influence of confinement. The second part addresses the formation and dynamics of microfoams, emphasizing structural differences from macroscopic foams and the influence of the confinement.

  8. Measuring bubbles in a bubbly wake flow

    Science.gov (United States)

    Lee, Seung-Jae; Kawakami, Ellison; Arndt, Roger E. A.

    2012-11-01

    This paper presents measurements of the velocity and size distribution of bubbles in a bubbly wake. This was carried out by utilizing particle shadow velocimetry (PSV). This technique is a non-scattering approach that relies on direct in-line volume illumination by a pulsed source such as a light-emitting diode (LED). A narrow depth-of-field (DoF) is required for imaging a 2-dimensional plane within a flow volume. Shadows of the bubbles were collected by a high-speed camera. Once a reference image, taken when no bubbles were present in the flow, was subtracted from the images, the image was segmented using an edge detection technique. The Canny algorithm was determined to be best suited for this application. A curvature profile method was employed to distinguish individual bubbles within a cluster of highly overlapping bubbles. The utilized algorithm was made to detect partly overlapping bubbles and reconstruct the missing parts. The movement of recognized individual bubbles was tracked on a two dimensional plane within a flow volume. In order to obtain quantitative results, the wake of a ventilated hydrofoil was investigated by applying the shadowgraphy technique and the described bubble detection algorithm. These experiments were carried out in the high speed cavitation tunnel at Saint Anthony Falls Laboratory (SAFL) of the University of Minnesota. This research is jointly sponsored by the Office of Naval Re- search, Dr. Ron Joslin, program manager, and the Department of Energy, Golden Field Office.

  9. Effect of Liquid Viscosity on a Liquid Jet Produced by the Collapse of a Laser-Induced Bubble near a Rigid Boundary

    Science.gov (United States)

    Liu, Xiu-mei; He, Jie; Lu, Jian; Ni, Xiao-wu

    2009-01-01

    The collapse of a laser-induced cavitation bubble near a rigid boundary and its dependence on liquid (kinematic) viscosity are investigated experimentally by fiber-coupling optical beam deflection (OBD). Cavitation bubble tests are performed using a mixture of glycerin and water of various concentrations, and the viscosity ranges from 1.004×10-6 to 51.30×10-6 m2/s. Combining the detection principles of this detector with a widely used laser ablation model, actual liquid-jet impact forces are presented for the mentioned viscosity range. In addition, based on the model of a collapsing bubble, some characteristic parameters, such as bubble lifetime, the maximum bubble radius, and liquid-jet impact pressure, are also obtained as a function of liquid viscosity. The main conclusion is that the liquid jet is a dominant factor in cavitation damage and can be modified by liquid viscosity. A high viscosity reduces the liquid-jet impact force and cavitation erosion markedly. The mechanism of the liquid viscosity effect on cavitation erosion has also been discussed.

  10. Effects of Ar or O2 Gas Bubbling for Shape, Size, and Composition Changes in Silver-Gold Alloy Nanoparticles Prepared from Galvanic Replacement Reaction

    Directory of Open Access Journals (Sweden)

    Md. Jahangir Alam

    2013-01-01

    Full Text Available The galvanic replacement reaction between silver nanostructures and AuCl4- solution has recently been demonstrated as a versatile method for generating metal nanostructures with hollow interiors. Here we describe the results of a systematic study detailing the morphological, structural, compositional, and spectral changes involved in such a heterogeneous reaction on the nanoscale. Effects of Ar or O2 gas bubbling for the formation of Ag-Au alloy nanoparticles by the galvanic replacement between spherical Ag nanoparticles and AuCl4- especially were studied in ethylene glycol (EG at 150°C. The shape, size, and composition changes occur rapidly under O2 bubbling in comparison with those under Ar bubbling. The major product after 60 min heating under Ar gas bubbling was perforated Ag-Au alloy particles formed by the replacement reaction and the minor product was ribbon-type particles produced from splitting off some perforated particles. On the other hand, the major product after 60 min heating under O2 gas bubbling was ribbon-type particles. In addition, small spherical Ag particles are produced. They are formed through rereduction of Ag+ ions released from the replacement reaction and oxidative etching of Ag nanoparticles by O2/Cl− in EG.

  11. Bubble Formation within Filaments of Melt-Processed Bi2212 wires and its strongly negative effect on the Critical Current Density

    CERN Document Server

    Kametani, F; Jiang, J; Scheuerlein, C; Malagoli, A; Di Michiel, M; Huang, Y; Miao, H; Parrell, J A; Hellstrom, E E; Larbalestier, D C

    2011-01-01

    Most studies of Bi2Sr2CaCu2Ox (Bi2212) show that the critical current density Jc is limited by the connectivity of the filaments, but what determines the connectivity is still elusive. Here we report on the role played by filament porosity in limiting Jc. By a microstructural investigation of wires quenched from the melt state, we find that porosity in the unreacted wire agglomerates into bubbles that segment the Bi2212 melt within the filaments into discrete sections. These bubbles do not disappear during subsequent processing because they are only partially filled by Bi2212 grains as the Bi2212 forms on cooling. Correlating the microstructure of quenched wires to their final, fully processed Jc values shows an inverse relation between Jc and bubble density. Bubbles are variable between conductors and perhaps from sample to sample, but they occur frequently and almost completely fill the filament diameter, so they exert a strongly variable but always negative effect on Jc. Bubbles reduce the continuous Bi221...

  12. Cusped Bubbles Rising through Polyelectrolyte Solutions

    Science.gov (United States)

    Belmonte, Andrew; Sostarecz, Michael

    2000-11-01

    It is well known that a bubble rising in a polymer fluid can have a cusp-like tail. We report on an experimental study of bubbles rising through solutions of glycerol/water with the addition of the polymer xanthan gum, a polyelectrolyte which becomes more rigid as the free ion concentration is increased. The addition of salt also decreases the elasticity of the xanthan gum solutions, and we observe its effects on the velocity and shape of the cusped bubble.

  13. Asset Bubbles, Endogenous Growth, and Financial Frictions

    OpenAIRE

    Hirano, Tomohiro; Yanagawa, Noriyuki

    2016-01-01

    This paper analyzes the effects of bubbles in an infinitely-lived agent model of endogenous growth with financial frictions and heterogeneous agents. We provide a complete characterization on the relationship between financial frictions and the existence of bubbles. Our model predicts that if the degree of pledgeability is sufficiently high or sufficiently low, bubbles can not exist. They can only arise at an intermediate degree. This suggests that improving the financial market condition mig...

  14. Fama on Bubbles

    DEFF Research Database (Denmark)

    Engsted, Tom

    2016-01-01

    . However, this argument cannot be used to rule out rational bubbles because such bubbles do not necessarily imply return predictability, and return predictability of the kind documented by Fama does not rule out rational bubbles. On data samples that include the 1990s, there is evidence of an explosive......While Eugene Fama has repeatedly expressed his discontent with the notion of an “irrational bubble,” he has never publicly expressed his opinion on “rational bubbles.” On empirical grounds Fama rejects bubbles by referring to the lack of reliable evidence that price declines are predictable...

  15. Effect of oxygen and heliox breathing on air bubbles in adipose tissue during 25-kPa altitude exposures

    DEFF Research Database (Denmark)

    Randsoe, T.; Kvist, T.M.; Hyldegaard, O.

    2008-01-01

    At altitude, bubbles are known to form and grow in blood and tissues causing altitude decompression sickness. Previous reports indicate that treatment of decompression sickness by means of oxygen breathing at altitude may cause unwanted bubble growth. In this report we visually followed the in vivo...... 30 to 130 min (mean: 67 min, +/-SD 31.0) from which point they stabilized or shrank slowly. No bubbles disappeared during either oxygen or heliox breathing. Preoxygenation followed by continuous oxygen breathing at altitude caused most bubbles to grow from 19 to 179 min (mean: 51 min, +/-SD 47...

  16. The Effects of Infection on Severe Stroke Patients in the Neurological Intensive Care Unit in China.

    Science.gov (United States)

    Mi, Heyin; Li, Shujuan; Li, Haiying; Hu, Wenli

    2017-12-05

    To study the effects of infection on severe stroke patients in the Neurological Intensive Care Unit (NICU) and to find the related risk factors for mortality of severe stroke patients. We conducted a retrospective study including 343 patients with ischemic or hemorrhagic stroke and staying more than 2 patient-days in the NICU at Beijing Chaoyang Hospital from January 2011 to December 2015 to analyze the infection features of patients with severe stroke in the Neurological Intensive Care Unit. The mortality rate, hospital staying time, hospital costs, infection time and different infection sources were analyzed and Logistic analysis was performed to find the related risk factors for mortality of severe stroke patients. All analysis were conducted using SPSS 18.0. The mortality rate, hospital staying time and hospital costs of stroke patients between infected and uninfected patients were higher in infected patients than the uninfected patients, P<0.05, and except for the hospital staying time, mortality rate and hospital costs were both significantly higher in infected patients. Respiratory tract infection was the most common infection type at all time periods, P<0.05. However, urinary tract infection increased at 72 h after stroke compared with the infection within 72 h after stroke. Blood sugar level, mean arterial pressure, scores of APACHE II, history of stoke, history of heart diseases, infections and respiratory tract infection were significantly different in dead patients compared with the alive patients, P<0.05. Logistic multivariate regression analysis showed that except for history of heart diseases, the other six factors were all associated with mortality of stroke patients and were independent risk factors for mortality of stroke patients. Infection can significantly influence the mortality rate, hospital costs of stroke patients and is an independent risk factors for mortality of stroke patients.

  17. Effects of ozone nano-bubble water on periodontopathic bacteria and oral cells - in vitro studies

    Science.gov (United States)

    Hayakumo, Sae; Arakawa, Shinichi; Takahashi, Masayoshi; Kondo, Keiko; Mano, Yoshihiro; Izumi, Yuichi

    2014-10-01

    The aims of the present study were to evaluate the bactericidal activity of a new antiseptic agent, ozone nano-bubble water (NBW3), against periodontopathogenic bacteria and to assess the cytotoxicity of NBW3 against human oral cells. The bactericidal activities of NBW3 against representative periodontopathogenic bacteria, Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) were evaluated using in vitro time-kill assays. The cytotoxicity of NBW3 was evaluated using three-dimensional human buccal and gingival tissue models. The numbers of colony forming units (CFUs)/mL of P. gingivalis and A. actinomycetemcomitans exposed to NBW3 dropped to below the lower limit of detection (therapy would be promising.

  18. Effect of grain morphology on gas bubble swelling in UMo fuels – A 3D microstructure dependent Booth model

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang; Burkes, Douglas; Lavender, Curt A.; Joshi, Vineet

    2016-11-01

    A three dimensional microstructure dependent swelling model is developed for studying the fission gas swelling kinetics in irradiated nuclear fuels. The model is extended from the Booth model [1] in order to investigate the effect of heterogeneous microstructures on gas bubble swelling kinetics. As an application of the model, the effect of grain morphology, fission gas diffusivity, and spatial dependent fission rate on swelling kinetics are simulated in UMo fuels. It is found that the decrease of grain size, the increase of grain aspect ratio for the grain having the same volume, and the increase of fission gas diffusivity (fission rate) cause the increase of swelling kinetics. Other heterogeneities such as second phases and spatial dependent thermodynamic properties including diffusivity of fission gas, sink and source strength of defects could be naturally integrated into the model to enhance the model capability.

  19. Effect of grain morphology on gas bubble swelling in UMo fuels – A 3D microstructure dependent Booth model

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang, E-mail: shenyang.hu@pnnl.gov; Burkes, Douglas; Lavender, Curt A.; Joshi, Vineet

    2016-11-15

    A three dimensional microstructure dependent swelling model is developed for studying the fission gas swelling kinetics in irradiated nuclear fuels. The model is extended from the Booth model [1] in order to investigate the effect of heterogeneous microstructures on gas bubble swelling kinetics. As an application of the model, the effect of grain morphology, fission gas diffusivity, and spatially dependent fission rate on swelling kinetics are simulated in UMo fuels. It is found that the decrease of grain size, the increase of grain aspect ratio for the grain having the same volume, and the increase of fission gas diffusivity (fission rate) cause the increase of swelling kinetics. Other heterogeneities such as second phases and spatially dependent thermodynamic properties including diffusivity of fission gas, sink and source strength of defects could be naturally integrated into the model to enhance the model capability.

  20. Neurological effects on startle response and escape from predation by medaka exposed to organic chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, R.; Drummond, R.; Hammermeister, D.; Bradbury, S. [Environmental Protection Agency, Duluth, MN (United States). Environmental Research Lab.

    1995-12-31

    Simultaneous electrophysiological and behavioral studies were performed on juvenile Japanese medaka (Oryzias latipes) exposed to representative neurotoxic organic chemicals at sublethal concentrations. Non-invasive recordings were made of the electrical impulses generated within giant neuronal Mauthner cells, associated interneurons or motoneurons, and musculature, all of which initiate the startle or escape response in fish. Timing in milliseconds between these electrical sequelae was measured for each fish before and at 24 and 48 hours exposure to a chemical. Also noted was the number of startle responses to number of stimuli ratio (R/S). Other groups of medaka were fed to bluegills and consumption times recorded to assess their ability to escape predation. These results were compared to neurophysiological effect levels. Phenol, 2,4-dinitrophenol, chlorpyrifos, fenvalerate, and 1-octanol impaired the ability of medaka to escape predation at all concentrations. Medaka were more susceptible to predation in high concentrations of carbaryl and strychnine, but less susceptible at low concentrations, whereas the reverse was true for endosulfan. The variety of neurological effects detected at these concentrations suggest that different mechanisms may be responsible. Phenol and strychnine affected Mauthner cell to motoneuron transmission, chlorpyrifos and carbaryl showed neuromuscular effects, and R/S was affected by most chemicals. Although a variety of neurotoxic mechanisms were examined, the exposure threshold for significant effects for each specific compound was found to be consistent for both the neurophysiological and behavioral endpoints.

  1. Effect of oxygen-breathing during a decompression-stop on bubble-induced platelet activation after an open-sea air dive: oxygen-stop decompression.

    Science.gov (United States)

    Pontier, J-M; Lambrechts, K

    2014-06-01

    We highlighted a relationship between decompression-induced bubble formation and platelet micro-particle (PMP) release after a scuba air-dive. It is known that decompression protocol using oxygen-stop accelerates the washout of nitrogen loaded in tissues. The aim was to study the effect of oxygen deco-stop on bubble formation and cell-derived MP release. Healthy experienced divers performed two scuba-air dives to 30 msw for 30 min, one with an air deco-stop and a second with 100% oxygen deco-stop at 3 msw for 9 min. Bubble grades were monitored with ultrasound and converted to the Kisman integrated severity score (KISS). Blood samples for cell-derived micro-particle analysis (AnnexinV for PMP and CD31 for endothelial MP) were taken 1 h before and after each dive. Mean KISS bubble score was significantly lower after the dive with oxygen-decompression stop, compared to the dive with air-decompression stop (4.3 ± 7.3 vs. 32.7 ± 19.9, p < 0.001). After the dive with an air-breathing decompression stop, we observed an increase of the post-dive mean values of PMP (753 ± 245 vs. 381 ± 191 ng/μl, p = 0.003) but no significant change in the oxygen-stop decompression dive (329 ± 215 vs. 381 +/191 ng/μl, p = 0.2). For the post-dive mean values of endothelial MP, there was no significant difference between both the dives. The Oxygen breathing during decompression has a beneficial effect on bubble formation accelerating the washout of nitrogen loaded in tissues. Secondary oxygen-decompression stop could reduce bubble-induced platelet activation and the pro-coagulant activity of PMP release preventing the thrombotic event in the pathogenesis of decompression sickness.

  2. Soap Bubbles and Crystals

    Indian Academy of Sciences (India)

    volume work summarizing his decades of research into soap bubbles and related phe- nomena due to surface tension. He gave the rules governing the geometry of bubbles, without any proof. It is a remarkable achievement as these experiments.

  3. Soap Bubbles and Logic.

    Science.gov (United States)

    Levine, Shellie-helane; And Others

    1986-01-01

    Introduces questions and activities involving soap bubbles which provide students with experiences in prediction and logic. Examines commonly held false conceptions related to the shapes that bubbles take and provides correct explanations for the phenomenon. (ML)

  4. Nonlinear ultrasonic waves in bubbly liquids with nonhomogeneous bubble distribution: Numerical experiments.

    Science.gov (United States)

    Vanhille, Christian; Campos-Pozuelo, Cleofé

    2009-06-01

    This paper deals with the nonlinear propagation of ultrasonic waves in mixtures of air bubbles in water, but for which the bubble distribution is nonhomogeneous. The problem is modelled by means of a set of differential equations which describes the coupling of the acoustic field and bubbles vibration, and solved in the time domain via the use and adaptation of the SNOW-BL code. The attenuation and nonlinear effects are assumed to be due to the bubbles exclusively. The nonhomogeneity of the bubble distribution is introduced by the presence of bubble layers (or clouds) which can act as acoustic screens, and alters the behaviour of the ultrasonic waves. The effect of the spatial distribution of bubbles on the nonlinearity of the acoustic field is analyzed. Depending on the bubble density, dimension, shape, and position of the layers, its effects on the acoustic field change. Effects such as shielding and resonance of the bubbly layers are especially studied. The numerical experiments are carried out in two configurations: linear and nonlinear, i.e. for low and high excitation pressure amplitude, respectively, and the features of the phenomenon are compared. The parameters of the medium are chosen such as to reproduce air bubbly water involved in the stable cavitation process.

  5. Autoregressive transitional ordinal model to test for treatment effect in neurological trials with complex endpoints

    Directory of Open Access Journals (Sweden)

    Lorenzo G. Tanadini

    2016-11-01

    Full Text Available Abstract Background A number of potential therapeutic approaches for neurological disorders have failed to provide convincing evidence of efficacy, prompting pharmaceutical and health companies to discontinue their involvement in drug development. Limitations in the statistical analysis of complex endpoints have very likely had a negative impact on the translational process. Methods We propose a transitional ordinal model with an autoregressive component to overcome previous limitations in the analysis of Upper Extremity Motor Scores, a relevant endpoint in the field of Spinal Cord Injury. Statistical power and clinical interpretation of estimated treatment effects of the proposed model were compared to routinely employed approaches in a large simulation study of two-arm randomized clinical trials. A revisitation of a key historical trial provides further comparison between the different analysis approaches. Results The proposed model outperformed all other approaches in virtually all simulation settings, achieving on average 14 % higher statistical power than the respective second-best performing approach (range: -1 %, +34 %. Only the transitional model allows treatment effect estimates to be interpreted as conditional odds ratios, providing clear interpretation and visualization. Conclusion The proposed model takes into account the complex ordinal nature of the endpoint under investigation and explicitly accounts for relevant prognostic factors such as lesion level and baseline information. Superior statistical power, combined with clear clinical interpretation of estimated treatment effects and widespread availability in commercial software, are strong arguments for clinicians and trial scientists to adopt, and further extend, the proposed approach.

  6. Effect of magnetic activity on plasma bubbles over equatorial and low-latitude regions in East Asia

    Directory of Open Access Journals (Sweden)

    G. Li

    2009-01-01

    Full Text Available The dependence of plasma bubble occurrence in the eveningside ionosphere, with magnetic activity during the period years 2001–2004, is studied here based on the TEC observations gathered by ground-based GPS receivers which are located in the equatorial and low-latitude regions in East Asia. The observed plasma bubbles consist of the plasma-bubble events in the equatorial (stations GUAM, PIMO and KAYT, and low-latitude regions (stations WUHN, DAEJ and SHAO. It is shown that most equatorial plasma-bubble events commence at 20:00 LT, and may last for >60 min. The magnetic activity appears to suppress the generation of equatorial plasma bubbles with a time delay of more than 3 h (4–9 h. While in the low-latitude regions, most plasma-bubble events commence at about 23:00 LT and last for <45 min. The best correlation between Kp and low-latitude plasma-bubble occurrence is found with an 8–9 h delay, a weak correlation exists for time delays of 6–7 h. This probably indicates that over 3 h delayed disturbance dynamo electric fields obviously inhibit the development of plasma bubbles in the pre-midnight sector.

  7. OXYGEN BUBBLE DEVELOPMENT ON A PLATINUM ELECTRODE IN BOROSILICATE GLASS MELT BY THE EFFECT OF ALTERNATING CURRENT

    Directory of Open Access Journals (Sweden)

    Jiri Matej

    2014-10-01

    or on alternating reduction and re-forming of oxidic layer on the electrode in the transition range, has been suggested. Start of bubble evolution at low alternating current density has also been observed in simple sodium-calcium-silicate glass melt. A relation between bubble release and platinum corrosion caused by reduced silicon has been suggested

  8. Soap Films and Bubbles.

    Science.gov (United States)

    Rice, Karen

    1986-01-01

    Develops and explains a format for a workshop which focuses on soap films and bubbles. The plan consists of: a discussion to uncover what children know about bubbles; explanations of the demonstration equipment; the presentation itself; the assembly of the workshop kit; and time to play with the bubbles. (ML)

  9. Storage of buffy-coat-derived platelets in additive solution: in vitro effects on platelets of the air bubbles and foam included in the final unit.

    Science.gov (United States)

    Sandgren, Per; Saeed, Kharija

    2011-04-01

    The air bubbles and foam that develop during the preparation of platelet units have traditionally been considered to interact with the platelets, causing activation and release reactions. However, there actually seems to be no data available concerning the platelet damage that may occur as a result of air bubbles and foam present in the final unit. In this in vitro study we, therefore, investigated the effects of not removing air bubbles/foam from final platelet units, by measuring in vitro parameters during a 7-day storage period. Platelet samples (n=8) from eight pools of 12 buffy-coats were aliquoted and prepared with the OrbiSac system for storage with (test) or without (reference) air bubbles/foam included in the final units. The metabolic, cellular and activation parameters of all units, comprising approximately 30% plasma and 70% SSP+ platelet additive solution, were analysed during the 7-day storage period. Differences in platelet counts and contents between the test and reference units were detected throughout storage (pstorage in the test units and was significantly higher than in the reference units (pstorage between the units (p=NS). Aggregates were visible (day 7) and occurred in three of the test units. pH was maintained at >6.8 (day 7) and swirling remained at the highest level (score =2) for all units throughout storage. This study shows that storage with air bubbles/foam causes considerable enhancement of disintegration of platelets. In addition, various in vitro parameters of the platelets remaining seem to be negatively affected. The results of this study suggest that platelets should be stored without air bubbles/foam, given that these cause increased disintegration of platelets.

  10. The effect of electrical conductivity on nanosecond discharges in distilled water and in methanol with argon bubbles

    KAUST Repository

    Hamdan, Ahmad

    2017-03-27

    We investigated the effect of a liquid\\'s electrical conductivity (EC) on the physical characteristics of electrical discharges in liquids with gaseous bubbles. Argon gas was supplied into the liquid to form an array of gaseous bubbles in between two electrodes (a pin-to-hollow electrode setup). Methanol and water were considered as base liquids, representing a low and a high dielectric permittivity (ϵ) liquid respectively, while potassium chloride (KCl) was added to control the EC of the liquids. When increasing the EC of the liquids, we found that the discharge probability was reduced by 46% for in-water and 38% for in-methanol discharges. We also found that the injected charge decreased by ∼4 μC as the EC increased. Moreover, as the gap distance increased from 1 to 2.5 mm, the injected charge decreased by 2 μC for in-water discharge and by 4 μC for in-methanol discharge. The plasma emission is another important parameter in characterizing discharges. With increasing the EC, the plasma emission volume decreased linearly by a factor of ∼5. The plasma lifetime was shortened by around 33% for in-water and 20% for in-methanol discharges in the case of d = 1 mm, while the decrease was 40% for in-water and 30% for in-methanol discharges in the case of d = 2.5 mm. Using the broadening characteristics of the Hα line, the electron density was estimated during the first 100 ns by ∼3 × 10 cm for in-water discharges and by ∼2 × 10 cm for in-methanol discharges, and it decreased by about one order of magnitude after 800 ns; note that n dependence on the EC was not significant. The reported findings provide further understanding of electrical discharges in bubbled liquids and highlight the influence of a liquid\\'s EC, which are useful in the development and optimization of the applications based on such process.

  11. Retrospective study of the clinical effects of acupuncture on cervical neurological diseases in dogs

    National Research Council Canada - National Science Library

    Liu, Ching Ming; Chang, Fang Chia; Lin, Chung Tien

    2016-01-01

    .... The interval between the neurological disease onset and treatment (duration of signs), time to improvement after treatment, and recovery time were compared in dogs by body weight, age, and dry needle acupuncture (AP...

  12. Cost-effectiveness of transfers to centers with neurological intensive care units after intracerebral hemorrhage.

    Science.gov (United States)

    Fletcher, Jeffrey J; Kotagal, Vikas; Mammoser, Aaron; Peterson, Mark; Morgenstern, Lewis B; Burke, James F

    2015-01-01

    Our aim was to estimate the cost-effectiveness of transferring patients with intracerebral hemorrhage from centers without specialized neurological intensive care units (neuro-ICUs) to centers with neuro-ICUs. Decision analytic models were developed for the lifetime horizons. Model inputs were derived from the best available data, informed by a variety of previous cost-effectiveness models of stroke. The effect of neuro-ICU care on functional outcomes was modeled in 3 scenarios. A favorable outcomes scenario was modeled based on the best observational data and compared with moderately favorable and least-favorable outcomes scenarios. Health benefits were measured in quality-adjusted life years (QALYs), and costs were estimated from a societal perspective. Costs were combined with QALYs gained to generate incremental cost-effectiveness ratios. One-way sensitivity analysis and Monte Carlo simulations were performed to test robustness of the model assumptions. Transferring patients to centers with neuro-ICUs yielded an incremental cost-effectiveness ratio for the lifetime horizon of $47,431 per QALY, $91,674 per QALY, and $380,358 per QALY for favorable, moderately favorable, and least-favorable scenarios, respectively. Models were robust at a willingness-to-pay threshold of $100,000 per QALY, with 95.5%, 75.0%, and 2.1% of simulations below the threshold for favorable, moderately favorable, and least-favorable scenarios, respectively. Transferring patients with intracerebral hemorrhage to centers with specialized neuro-ICUs is cost-effective if observational estimates of the neuro-ICU-based functional outcome distribution are accurate. If future work confirms these functional outcome distributions, then a strong societal rationale exists to build systems of care designed to transfer intracerebral hemorrhage patients to specialized neuro-ICUs. © 2014 American Heart Association, Inc.

  13. [Evaluation of repetitive transcranial magnetic stimulation effectiveness in treatment of psychiatric and neurologic diseases].

    Science.gov (United States)

    Pastuszak, Żanna; Stępień, Anna; Piusińska-Macoch, Renata; Brodacki, Bogdan; Tomczykiewicz, Kazimierz

    2016-06-01

    Repetitive transcranial magnetic stimulation (rTMS) is a treatment option with proved effectiveness especially in drug resist depression. It is used in functional brain mapping before neurosurgery operations and diagnostic of corticospinal tract transmission. Many studies are performed to evaluate rTMS using in treatment of obsessive - compulsive disorder, schizophrenia, autism, strokes, tinnitus, Alzheimer and Parkinson diseases, cranial traumas. Moreover rTMS was used in treatment of multiple sclerosis, migraine, dystonia. Electromagnetical field generated by rTMS penetrate skin of the scalp and infiltrate brain tissues to a depth of 2 cm, cause neurons depolarization and generating motor, cognitive and affective effects. Depending on the stimulation frequency rTMS can stimuli or inhibit brain cortex. rTMS mechanism of action remains elusive. Probably it is connected with enhancement of neurotransmitters, modulation of signals transductions pathways in Central Nervous System, gene transcription and release of neuroprotective substances. Studies with use of animals revealed that rTMS stimulation can generate brain changes similar to those seen after electric shock therapy without provoking seizures. The aim of presenting study was to analyze actual researches evaluating rTMS use in treatment of psychiatric and neurological diseases. © 2016 MEDPRESS.

  14. [Meta-analytic assessment of parenteral cytoflavin effectiveness in different neurologic disorders].

    Science.gov (United States)

    Mazin, P V; Sheshunov, I V; Mazina, N K

    To carry out an integral quantitative assessment of the clinical efficacy of parenteral use of cytoflavin in treatment of patients with CNS disorders based on the systemic selection of published controlled clinical trials and their meta-analysis. Twenty-one high evidence-based studies on the efficacy of parenteral use of cytoflavin in different CNS disorders (4314 patients) have been analyzed. Comparisons with basic treatment groups were undertaken to clarify the drug clinical effects adjusted for heterogeneity and variability of response parameters. An analysis of formalized efficacy indicators (increase in the absolute and relative value, odds ratio (OR) etc.) has demonstrated the advantages of cytoflavin. Group combination has increased the statistical power of the meta-analysis. Two models with fixed (Mantel-Haenszel amendment) and random effects were used. All the estimation protocols in different clinical groups of patients with neurologic diseases provided similar results and confirmed the stability of calculated values irrespective of heterogeneity of data arrays. OR of positive outcomes in neuropathologies treated with cytoflavin was 3,02 with χ2 heterogeneity 427,3 and p = 0,000…, I2= 85,7% (82%; 88%).

  15. Adult neurology training during child neurology residency.

    Science.gov (United States)

    Schor, Nina F

    2012-08-21

    As it is currently configured, completion of child neurology residency requires performance of 12 months of training in adult neurology. Exploration of whether or not this duration of training in adult neurology is appropriate for what child neurology is today must take into account the initial reasons for this requirement and the goals of adult neurology training during child neurology residency.

  16. Computational Fluid Dynamics-Population Balance Model Simulation of Effects of Cell Design and Operating Parameters on Gas-Liquid Two-Phase Flows and Bubble Distribution Characteristics in Aluminum Electrolysis Cells

    Science.gov (United States)

    Zhan, Shuiqing; Wang, Junfeng; Wang, Zhentao; Yang, Jianhong

    2018-02-01

    The effects of different cell design and operating parameters on the gas-liquid two-phase flows and bubble distribution characteristics under the anode bottom regions in aluminum electrolysis cells were analyzed using a three-dimensional computational fluid dynamics-population balance model. These parameters include inter-anode channel width, anode-cathode distance (ACD), anode width and length, current density, and electrolyte depth. The simulations results show that the inter-anode channel width has no significant effect on the gas volume fraction, electrolyte velocity, and bubble size. With increasing ACD, the above values decrease and more uniform bubbles can be obtained. Different effects of the anode width and length can be concluded in different cell regions. With increasing current density, the gas volume fraction and electrolyte velocity increase, but the bubble size keeps nearly the same. Increasing electrolyte depth decreased the gas volume fraction and bubble size in particular areas and the electrolyte velocity increased.

  17. Computational Fluid Dynamics-Population Balance Model Simulation of Effects of Cell Design and Operating Parameters on Gas-Liquid Two-Phase Flows and Bubble Distribution Characteristics in Aluminum Electrolysis Cells

    Science.gov (United States)

    Zhan, Shuiqing; Wang, Junfeng; Wang, Zhentao; Yang, Jianhong

    2017-11-01

    The effects of different cell design and operating parameters on the gas-liquid two-phase flows and bubble distribution characteristics under the anode bottom regions in aluminum electrolysis cells were analyzed using a three-dimensional computational fluid dynamics-population balance model. These parameters include inter-anode channel width, anode-cathode distance (ACD), anode width and length, current density, and electrolyte depth. The simulations results show that the inter-anode channel width has no significant effect on the gas volume fraction, electrolyte velocity, and bubble size. With increasing ACD, the above values decrease and more uniform bubbles can be obtained. Different effects of the anode width and length can be concluded in different cell regions. With increasing current density, the gas volume fraction and electrolyte velocity increase, but the bubble size keeps nearly the same. Increasing electrolyte depth decreased the gas volume fraction and bubble size in particular areas and the electrolyte velocity increased.

  18. Analysis of the effect of impact of near-wall acoustic bubble collapse micro-jet on Al 1060.

    Science.gov (United States)

    Ye, Linzheng; Zhu, Xijing

    2017-05-01

    The bubble collapse near a wall will generate strong micro-jet in a liquid environment under ultrasonic field. To explore the effect of the impact of near-wall acoustic bubble collapse micro-jet on an aluminum 1060 sheet, the cavitation threshold formula and micro-jet velocity formula were first proposed. Then the Johnson-Cook rate correlation material constitutive model was considered, and a three-dimensional fluid-solid coupling model of micro-jet impact on a wall was established and analyzed. Finally, to validate the model, ultrasonic cavitation test and inversion analysis based on the theory of spherical indentation test were conducted. The results show that cavitation occurs significantly in the liquid under ultrasonic field, as the applied ultrasonic pressure amplitude is much larger than liquid cavitation threshold. Micro pits appear on the material surface under the impact of micro-jet. Pit depth is determined by both micro-jet velocity and micro-jet diameter, and increases with their increase. Pit diameter is mainly related to the micro-jet diameter and dp/dj≈0.95-1.2, while pit's diameter-to-depth ratio is mainly negatively correlated with the micro-jet velocity. Wall pressure distribution is mostly symmetric and its maximum appears on the edge of micro-jet impingement. Obviously, the greater the micro-jet velocity is, the greater the wall pressure is. Micro pits formed after the impact of micro-jet on aluminum 1060 surface were assessed by ultrasonic cavitation test. Inversion analysis results indicate that equivalent stress, equivalent strain of the pit and impact strength, and velocity of the micro-jet are closely related with pit's diameter-to-depth ratio. For the pit's diameter-to-depth ratio of 16-68, the corresponding micro-jet velocity calculated is 310-370m/s. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Microstructure of HIPed and SPSed 9Cr-ODS steel and its effect on helium bubble formation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chenyang [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, Liaoning (China); Department of Nuclear Engineering and Radiological Science, University of Michigan, Ann Arbor, MI, 48109 (United States); Lu, Zheng, E-mail: luz@atm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, Liaoning (China); Xie, Rui; Liu, Chunming [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, Liaoning (China); Wang, Lumin, E-mail: lmwang@umich.edu [Department of Nuclear Engineering and Radiological Science, University of Michigan, Ann Arbor, MI, 48109 (United States)

    2016-06-15

    Two 9Cr-ODS steels with the same nominal composition were consolidated by hot isostatic pressing (HIP, named COS-1) and spark plasma sintering (SPS, named COS-2). Helium ions were implanted into COS-1, COS-2 and non-ODS Eurofer 97 steels up at 673 K. Microstructures before and after helium ion implantations were carefully characterized. The results show a bimodal grain size distribution in COS-2 and a more uniform grain size distribution in COS-1. Nanoscale clusters of GP-zone type Y–Ti–O and Y{sub 2}Ti{sub 2}O{sub 7} pyrochlore as well as large spinel Mn(Ti)Cr{sub 2}O{sub 4} particles are all observed in the two ODS steels. The Y–Ti-enriched nano-oxides in COS-1 exhibit higher number density and smaller size than in COS-2. The Y–Ti-enriched nano-oxides in fine grains of COS-2 show higher number density and smaller size than that in coarse grains of COS-2. Nano-oxides effectively trap helium atoms and lead to the formation of high density and ultra-fine helium bubbles. - Highlights: • The microstructure changes of two ODS steels before and after helium ion implantation have been elucidated. • The mechanism of the microstructures of ODS steels under varied thermal mechanical processing paths have been explored. • The dependence of the size, density and distribution of helium bubbles on the specific microstructure features are explored.

  20. Cavitation bubble dynamics.

    Science.gov (United States)

    Lauterborn, W; Ohl, C D

    1997-04-01

    The dynamics of cavitation bubbles on water is investigated for bubbles produced optically and acoustically. Single bubble dynamics is studied with laser produced bubbles and high speed photography with framing rates up to 20.8 million frames per second. Examples for jet formation and shock wave emission are given. Acoustic cavitation is produced in water in the interior of piezoelectric cylinders of different sizes (up to 12 cm inner diameter). The filementary structure composed of bubbles is investigated and their light emission (sonoluminescence) studied for various driving strengths.

  1. [A Study on the Cognitive Learning Effectiveness of Scenario-Based Concept Mapping in a Neurological Nursing Course].

    Science.gov (United States)

    Pan, Hui-Ching; Hsieh, Suh-Ing; Hsu, Li-Ling

    2015-12-01

    The multiple levels of knowledge related to the neurological system deter many students from pursuing studies on this topic. Thus, in facing complicated and uncertain medical circumstances, nursing students have diffi-culty adjusting and using basic neurological-nursing knowledge and skills. Scenario-based concept-mapping teaching has been shown to promote the integration of complicated data, clarify related concepts, and increase the effectiveness of cognitive learning. To investigate the effect on the neurological-nursing cognition and learning attitude of nursing students of a scenario-based concept-mapping strategy that was integrated into the neurological nursing unit of a medical and surgical nursing course. This quasi-experimental study used experimental and control groups and a pre-test / post-test design. Sopho-more (2nd year) students in a four-year program at a university of science and technology in Taiwan were convenience sampled using cluster randomization that was run under SPSS 17.0. Concept-mapping lessons were used as the intervention for the experimental group. The control group followed traditional lesson plans only. The cognitive learning outcome was measured using the neurological nursing-learning examination. Both concept-mapping and traditional lessons significantly improved post-test neurological nursing learning scores (p learning attitude with regard to the teaching material. Furthermore, a significant number in the experimental group expressed the desire to add more lessons on anatomy, physiology, and pathology. These results indicate that this intervention strategy may help change the widespread fear and refusal of nursing students with regard to neurological lessons and may facilitate interest and positively affect learning in this important subject area. Integrating the concept-mapping strategy and traditional clinical-case lessons into neurological nursing lessons holds the potential to increase post-test scores significantly

  2. Ethnic diversity deflates price bubbles

    Science.gov (United States)

    Levine, Sheen S.; Apfelbaum, Evan P.; Bernard, Mark; Bartelt, Valerie L.; Zajac, Edward J.; Stark, David

    2014-01-01

    Markets are central to modern society, so their failures can be devastating. Here, we examine a prominent failure: price bubbles. Bubbles emerge when traders err collectively in pricing, causing misfit between market prices and the true values of assets. The causes of such collective errors remain elusive. We propose that bubbles are affected by ethnic homogeneity in the market and can be thwarted by diversity. In homogenous markets, traders place undue confidence in the decisions of others. Less likely to scrutinize others’ decisions, traders are more likely to accept prices that deviate from true values. To test this, we constructed experimental markets in Southeast Asia and North America, where participants traded stocks to earn money. We randomly assigned participants to ethnically homogeneous or diverse markets. We find a marked difference: Across markets and locations, market prices fit true values 58% better in diverse markets. The effect is similar across sites, despite sizeable differences in culture and ethnic composition. Specifically, in homogenous markets, overpricing is higher as traders are more likely to accept speculative prices. Their pricing errors are more correlated than in diverse markets. In addition, when bubbles burst, homogenous markets crash more severely. The findings suggest that price bubbles arise not only from individual errors or financial conditions, but also from the social context of decision making. The evidence may inform public discussion on ethnic diversity: it may be beneficial not only for providing variety in perspectives and skills, but also because diversity facilitates friction that enhances deliberation and upends conformity. PMID:25404313

  3. Ethnic diversity deflates price bubbles.

    Science.gov (United States)

    Levine, Sheen S; Apfelbaum, Evan P; Bernard, Mark; Bartelt, Valerie L; Zajac, Edward J; Stark, David

    2014-12-30

    Markets are central to modern society, so their failures can be devastating. Here, we examine a prominent failure: price bubbles. Bubbles emerge when traders err collectively in pricing, causing misfit between market prices and the true values of assets. The causes of such collective errors remain elusive. We propose that bubbles are affected by ethnic homogeneity in the market and can be thwarted by diversity. In homogenous markets, traders place undue confidence in the decisions of others. Less likely to scrutinize others' decisions, traders are more likely to accept prices that deviate from true values. To test this, we constructed experimental markets in Southeast Asia and North America, where participants traded stocks to earn money. We randomly assigned participants to ethnically homogeneous or diverse markets. We find a marked difference: Across markets and locations, market prices fit true values 58% better in diverse markets. The effect is similar across sites, despite sizeable differences in culture and ethnic composition. Specifically, in homogenous markets, overpricing is higher as traders are more likely to accept speculative prices. Their pricing errors are more correlated than in diverse markets. In addition, when bubbles burst, homogenous markets crash more severely. The findings suggest that price bubbles arise not only from individual errors or financial conditions, but also from the social context of decision making. The evidence may inform public discussion on ethnic diversity: it may be beneficial not only for providing variety in perspectives and skills, but also because diversity facilitates friction that enhances deliberation and upends conformity.

  4. Neurology in Asia.

    Science.gov (United States)

    Tan, Chong-Tin

    2015-02-10

    Asia is important as it accounts for more than half of the world population. The majority of Asian countries fall into the middle income category. As for cultural traditions, Asia is highly varied, with many languages spoken. The pattern of neurologic diseases in Asia is largely similar to the West, with some disease features being specific to Asia. Whereas Asia constitutes 60% of the world's population, it contains only 20% of the world's neurologists. This disparity is particularly evident in South and South East Asia. As for neurologic care, it is highly variable depending on whether it is an urban or rural setting, the level of economic development, and the system of health care financing. To help remedy the shortage of neurologists, most counties with larger populations have established training programs in neurology. These programs are diverse, with many areas of concern. There are regional organizations serving as a vehicle for networking in neurology and various subspecialties, as well as an official journal (Neurology Asia). The Asian Epilepsy Academy, with its emphasis on workshops in various locations, EEG certification examination, and fellowships, may provide a template of effective regional networking for improving neurology care in the region. © 2015 American Academy of Neurology.

  5. The effects of geometric, flow, and boiling parameters on bubble growth and behavior in subcooled flow boiling

    Science.gov (United States)

    Samaroo, Randy

    Air bubble injection and subcooled flow boiling experiments have been performed to investigate the liquid flow field and bubble nucleation, growth, and departure, in part to contribute to the DOE Nuclear HUB project, Consortium for Advanced Simulation of Light Water Reactors (CASL). The main objective was to obtain quantitative data and compartmentalize the many different interconnected aspects of the boiling process -- from the channel geometry, to liquid and gas interactions, to underlying heat transfer mechanisms. The air bubble injection experiments were performed in annular and rectangular geometries and yielded data on bubble formation and departure from a small hole on the inner tube surface, subsequent motion and deformation of the detached bubbles, and interactions with laminar or turbulent water flow. Instantaneous and ensemble- average liquid velocity profiles have been obtained using a Particle Image Velocimetry technique and a high speed video camera. Reynolds numbers for these works ranged from 1,300 to 7,700. Boiling experiments have been performed with subcooled water at atmospheric pres- sure in the same annular channel geometry as the air injection experiments. A second flow loop with a slightly larger annular channel was constructed to perform further boiling experiments at elevated pressures up to 10 bar. High speed video and PIV measurements of turbulent velocity profiles in the presence of small vapor bubbles on the heated rod are presented. The liquid Reynolds number for this set of experiments ranged from 5,460 to 86,000. It was observed that as the vapor bubbles are very small compared to the injected air bubbles, further experiments were performed using a microscopic objective to obtain higher spatial resolution for velocity fields near the heated wall. Multiple correlations for the bubble liftoff diameter, liftoff time and bub- ble history number were evaluated against a number of experimental datasets from previous works, resulting in a

  6. Oscillation of large air bubble cloud

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Y.Y.; Kim, H.Y.; Park, J.K. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)

    2001-07-01

    The behavior of a large air bubble cloud, which is generated by the air discharged from a perforated sparger, is analyzed by solving Rayleigh-Plesset equation, energy equations and energy balance equation. The equations are solved by Runge-Kutta integration and MacCormack finite difference method. Initial conditions such as driving pressure, air volume, and void fraction strongly affect the bubble pressure amplitude and oscillation frequency. The pool temperature has a strong effect on the oscillation frequency and a negligible effect on the pressure amplitude. The polytropic constant during the compression and expansion processes of individual bubbles ranges from 1.0 to 1.4, which may be attributed to the fact that small bubbles oscillated in frequencies different from their resonance. The temperature of the bubble cloud rapidly approaches the ambient temperature, as is expected from the polytropic constants being between 1.0 and 1.4. (authors)

  7. Bubbles as a means for the deaeration of water bodies

    NARCIS (Netherlands)

    Zhang, Yuhang; Zhou, Gedi; Prosperetti, Andrea

    2017-01-01

    Occasional dissolved-air supersaturation - such as may occur, for instance, downstream of dams - is harmful to fish because it causes gas bubble disease. A counterintuitive but effective means of reducing dissolved air content is the injection of bubbles in the supersaturated water. The bubbles

  8. Maximal air bubble entrainment at liquid-drop impact

    NARCIS (Netherlands)

    Bouwhuis, W.; van der Veen, Roeland; Tran, Tuan; Keij, D.L.; Winkels, K.G.; Peters, I.R.; van der Meer, Roger M.; Sun, Chao; Snoeijer, Jacobus Hendrikus; Lohse, Detlef

    2012-01-01

    At impact of a liquid drop on a solid surface, an air bubble can be entrapped. Here, we show that two competing effects minimize the (relative) size of this entrained air bubble: for large drop impact velocity and large droplets, the inertia of the liquid flattens the entrained bubble, whereas for

  9. Effect of operating conditions on the performance of the bubble pump of absorption-diffusion refrigeration cycles

    National Research Council Canada - National Science Library

    Benhmidene Ali; Chaouachi Bechir; Gabsi Slimane

    2011-01-01

    ...….). That will result in a successful bubble pump design and hence a refrigeration unit. In the present work a one-dimensional two-fluid model of boiling mixing ammonia-water under constant heat flux is developed...

  10. Behavioral and neurological effects of symptomatic and asymptomatic lead exposure in children

    Energy Technology Data Exchange (ETDEWEB)

    Rummo, J.H.; Routh, D.K.; Rummo, N.J.; Brown, J.F.

    1979-03-01

    Forty-five children 4 to 8 y of age who had been exposed to environmental lead were studied, consisting of an acute encephalopathy group and groups with short- and long-term exposure but without encephalopathy. Control children were matched for age, sex, race, and socioeconomic status with lead-exposed subjects, but lived in post-1945 housing and had negative neurological history and blood tests. The encephalopathy group had a significantly higher incidence of neurological deficits, retarded mental development, and higher hyperactivity than control subjects. Children with short- and long-term exposure short of encephalopathy were somewhat inferior to matched control subjects, but not to a statistically significant extent.

  11. Simulations of Bubble Motion in an Oscillating Liquid

    Science.gov (United States)

    Kraynik, A. M.; Romero, L. A.; Torczynski, J. R.

    2010-11-01

    Finite-element simulations are used to investigate the motion of a gas bubble in a liquid undergoing vertical vibration. The effect of bubble compressibility is studied by comparing "compressible" bubbles that obey the ideal gas law with "incompressible" bubbles that are taken to have constant volume. Compressible bubbles exhibit a net downward motion away from the free surface that does not exist for incompressible bubbles. Net (rectified) velocities are extracted from the simulations and compared with theoretical predictions. The dependence of the rectified velocity on ambient gas pressure, bubble diameter, and bubble depth are in agreement with the theory. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Effect of adjuvant argatroban therapy on neurological function, endothelial injury and inflammation state in patient with acute cerebral infarction

    Directory of Open Access Journals (Sweden)

    Nan Che

    2016-08-01

    Full Text Available Objective: To analyze the effect of adjuvant argatroban therapy on neurological function, endothelial injury and inflammation state in patient with acute cerebral infarction. Methods: A total of 118 patients with acute cerebral infarction were divided into observation group and control group according to the random number table, control group received conventional treatment, observation group received argatroban + conventional treatment, and then differences in TCD cerebral blood flow, serum neurological function, endothelial injury and inflammatory marker levels were compared between two groups after treatment. Results: TCD MCA and ACA values of observation group after treatment were higher than those of control group (P<0.05; serum neurological function indexes copeptin, NT-proBNP, PAO and S-100B levels of observation group after treatment were lower than those of control group, endothelial injury index ET-1 level was lower than that of control group, NO and CGRP levels were higher than those of control group, and inflammatory markers hs-CRP, TNF-毩, IL-6, MMP-9 and Lp-PLA2 levels were lower than those of control group (P<0.05. Conclusions: Adjuvant argatroban therapy can optimize the overall condition in patients with acute cerebral infarction, and plays a positive role in improving the neurological function, reducing endothelial injury and inflammation state, etc.

  13. Overview of developmental, reproductive, and behavioral/ neurological effects of mercury exposures in wildlife

    Science.gov (United States)

    Heinz, G.H.; Hoffman, D.; Klimstra, J.; Stebbins, K.

    2007-01-01

    We review wildlife/mercury literature and our own research findings that demonstrate the relevance of wildlife toxicity data in protecting human health. Methylmercury affects wildlife through reduced adult survival and reproduction, aberrant behavior, immune system effects, and teratogenic effects. Methylmercury can readily cross the blood-brain barrier, is excreted into eggs in birds, and is transferred to young mammals across the placenta and in milk. Its principal effect on wildlife is on neurological functions. Wild mink (Mustela vison) and otter (Lutra canadensis) have died from methylmercury poisoning, with signs of poisoning including anorexia, loss of weight, incoordination, tremors, and convulsions, which are symptoms similar to those experienced by mercury-poisoned humans. Mammals also may experience tonic and clonic convulsions and an increase in fetal anomalies, again paralleling toxic problems in people. Antibody-producing cells can be suppressed by methylmercury. Microscopically, the most notable lesions are in the cerebrum. Extensive vacuolation of hepatocytes in the liver and necrosis and other changes in the appearance of the proximal convoluted tubules of the kidneys are often noted. When harp seals (Pagophilus groenlandicus) were dosed with methylmercury chloride the number of circulating erythrocytes decreased and white blood cell counts greatly increased. The poisoned seals also suffered from uremia, hyperproteinemia, hypercholesterolemia, hyperbilirubinemia, and elevations in lactic dehydrogenase and alkaline phosphatase. In birds, signs of methylmercury poisoning included emaciation and weakness in the extremities, which progressed until the birds died. Mercury poisoning in birds and mammals can be diagnosed from a combination of the signs of poisoning if the animal is still alive, the pathological effects seen in a gross necropsy, the histopathological effects seen with a microscope, and the concentrations of mercury in various tissues. Our

  14. Effectiveness of stretch for the treatment and prevention of contractures in people with neurological conditions: a systematic review.

    Science.gov (United States)

    Katalinic, Owen M; Harvey, Lisa A; Herbert, Robert D

    2011-01-01

    Contractures are a disabling complication of neurological conditions that are commonly managed with stretch. The purpose of this systematic review was to determine the effectiveness of stretch for the treatment and prevention of contractures. The review is part of a more-detailed Cochrane review. Only the results of the studies including patients with neurological conditions are reported here. Electronic searches were conducted in June 2010 in the following computerized databases: Cochrane CENTRAL Register of Controlled Trials, Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment Database (HTA), MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), EMBASE, SCI-EXPANDED, and Physiotherapy Evidence Database (PEDro). The review included randomized controlled trials and controlled clinical trials of stretch applied for the purposes of treating or preventing contractures in people with neurological conditions. Two reviewers independently selected studies, extracted data, and assessed risk of bias. The primary outcome measures were joint mobility (range of motion) and quality of life. Secondary outcome measures were pain, spasticity, activity limitation, and participation restriction. Meta-analyses were conducted using random-effects models. Twenty-five studies met the inclusion criteria. These studies provide moderate-quality evidence that stretch has a small immediate effect on joint mobility (mean difference=3°, 95% confidence interval [CI]=0° to 5°) and high-quality evidence that stretch has little or no short-term or long-term effects on joint mobility (mean difference=1° and 0°, respectively, 95% CI=0° to 3° and -2° to 2°, respectively). There is little or no effect of stretch on pain, spasticity, and activity limitation. No studies were retrieved that investigated the effects of stretch for longer than 6 months. Regular stretch does not produce clinically important changes in joint mobility, pain

  15. Combination of bubble liposomes and high-intensity focused ultrasound (HIFU) enhanced antitumor effect by tumor ablation.

    Science.gov (United States)

    Hamano, Nobuhito; Negishi, Yoichi; Takatori, Kyohei; Endo-Takahashi, Yoko; Suzuki, Ryo; Maruyama, Kazuo; Niidome, Takuro; Aramaki, Yukihiko

    2014-01-01

    Ultrasound (US) is used in the clinical setting not only for diagnosis but also for therapy. As a therapeutic US technique, high-intensity focused ultrasound (HIFU) can be applied to treat cancer in a clinical setting. Microbubbles increased temperature and improved the low therapeutic efficiency under HIFU; however, microbubbles have room for improvement in size, stability, and targeting ability. To solve these issues, we reported that "Bubble liposomes" (BLs) containing the US imaging gas (perfluoropropane gas) liposomes were suitable for ultrasound imaging and gene delivery. In this study, we examined whether BLs and HIFU could enhance the ablation area of the tumor and the antitumor effect. First, we histologically analyzed the tumor after BLs and HIFU. The ablation area of the treatment of BLs and HIFU was broader than that of HIFU alone. Next, we monitored the temperature of the tumor, and examined the antitumor effect. The temperature increase with BLs and HIFU treatment was faster and higher than that with HIFU alone. Moreover, treatment with BLs and HIFU enhanced the antitumor effect, which was better than with HIFU alone. Thus, the combination of BLs and HIFU could be efficacious for cancer therapy.

  16. Bubble Movement on Inclined Hydrophobic Surfaces.

    Science.gov (United States)

    Kibar, Ali; Ozbay, Ridvan; Sarshar, Mohammad Amin; Kang, Yong Tae; Choi, Chang-Hwan

    2017-10-31

    The movement of a single air bubble on an inclined hydrophobic surface submerged in water, including both the upward- and downward-facing sides of the surface, was investigated. A planar Teflon sheet with an apparent contact angle of a sessile water droplet of 106° was used as a hydrophobic surface. The volume of a bubble and the inclination angle of a Teflon sheet varied in the ranges 5-40 μL and 0-45°, respectively. The effects of the bubble volume on the adhesion and dynamics of the bubble were studied experimentally on the facing-up and facing-down surfaces of the submerged hydrophobic Teflon sheet, respectively, and compared. The result shows that the sliding angle has an inverse relationship with the bubble volume for both the upward- and downward-facing surfaces. However, at the same given volume, the bubble on the downward-facing surface spreads over a larger area of the hydrophobic surface than the upward-facing surface due to the greater hydrostatic pressure acting on the bubble on the downward-facing surface. This makes the lateral adhesion force of the bubble greater and requires a larger inclination angle to result in sliding.

  17. Bubble streams rising beneath an inclined surface

    Science.gov (United States)

    Bird, James; Brasz, Frederik; Kim, Dayoung; Menesses, Mark; Belden, Jesse

    2017-11-01

    Bubbles released beneath a submerged inclined surface can tumble along the wall as they rise, dragging the surrounding fluid with them. This effect has recently regained attention as a method to mitigate biofouling in marine environment, such as a ship hull. It appears that the efficacy of this approach may be related to the velocity of the rising bubbles and the extent that they spread laterally as they rise. Yet, it is unclear how bubble stream rise velocity and lateral migration depend on bubble size, flow rate, and inclination angle. Here we perform systematic experiments to quantify these relationships for both individual bubble trajectories and ensemble average statistics. Research supported by the Office of Naval Research under Grant Number award N00014-16-1-3000.

  18. Planar Soap Bubbles

    OpenAIRE

    Vaughn, Rick

    1998-01-01

    The generalized soap bubble problem seeks the least perimeter way to enclose and separate n given volumes in R^m. We study the possible configurations for perimeter minimizing bubble complexes enclosing more than two regions. We prove that perimeter minimizing planar bubble complexes with equal pressure regions and without empty chambers must have connected regions. As a consequence, we show that the least perimeter planar graph that...

  19. Magnetic bubble materials.

    Science.gov (United States)

    Giess, E A

    1980-05-23

    Physicists, materials scientists, and engineers combined to bring solid-state bubble devices into the computer memory and recording marketplace. Devices with smaller bubbles are being developed for increased data capacity and lower cost. Epitaxial garnet films made by isothermal dipping in molten solutions helped put the technology in place and will probably satisfy the material needs of future devices with bubbles scaled down from 2 to 0.5 micrometer in size.

  20. Wikipedia and neurological disorders.

    Science.gov (United States)

    Brigo, Francesco; Igwe, Stanley C; Nardone, Raffaele; Lochner, Piergiorgio; Tezzon, Frediano; Otte, Willem M

    2015-07-01

    Our aim was to evaluate Wikipedia page visits in relation to the most common neurological disorders by determining which factors are related to peaks in Wikipedia searches for these conditions. Millions of people worldwide use the internet daily as a source of health information. Wikipedia is a popular free online encyclopedia used by patients and physicians to search for health-related information. The following Wikipedia articles were considered: Alzheimer's disease; Amyotrophic lateral sclerosis; Dementia; Epilepsy; Epileptic seizure; Migraine; Multiple sclerosis; Parkinson's disease; Stroke; Traumatic brain injury. We analyzed information regarding the total article views for 90 days and the rank of these articles among all those available in Wikipedia. We determined the highest search volume peaks to identify possible relation with online news headlines. No relation between incidence or prevalence of neurological disorders and the search volume for the related articles was found. Seven out of 10 neurological conditions showed relations in search volume peaks and news headlines. Six out of these seven peaks were related to news about famous people suffering from neurological disorders, especially those from showbusiness. Identification of discrepancies between disease burden and health seeking behavior on Wikipedia is useful in the planning of public health campaigns. Celebrities who publicly announce their neurological diagnosis might effectively promote awareness programs, increase public knowledge and reduce stigma related to diagnoses of neurological disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Sonochemistry and bubble dynamics.

    Science.gov (United States)

    Mettin, Robert; Cairós, Carlos; Troia, Adriano

    2015-07-01

    The details of bubble behaviour in chemically active cavitation are still not sufficiently well understood. Here we report on experimental high-speed observations of acoustically driven single-bubble and few-bubble systems with the aim of clarification of the connection of their dynamics with chemical activity. Our experiment realises the sonochemical isomerization reaction of maleic acid to fumaric acid, mediated by bromine radicals, in a bubble trap set-up. The main result is that the reaction product can only be observed in a parameter regime where a small bubble cluster occurs, while a single trapped bubble stays passive. Evaluations of individual bubble dynamics for both cases are given in form of radius-time data and numerical fits to a bubble model. A conclusion is that a sufficiently strong collapse has to be accompanied by non-spherical bubble dynamics for the reaction to occur, and that the reason appears to be an efficient mixing of liquid and gas phase. This finding corroborates previous observations and literature reports on high liquid phase sonochemical activity under distinct parameter conditions than strong sonoluminescence emissions. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Bubble and drop interfaces

    CERN Document Server

    Miller

    2011-01-01

    The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles. Besides the details of experimental set ups, also the underlying theoretical basis is presented in detail. In addition, a number of applications based on drops and bubbles is discussed, such as rising bubbles and the very complex process of flotation. Also wetting, characterized by the dynamics of advancing contact angles is discussed critically. Spec

  3. Effective prophylaxis of visual and neurological disturbances with an anti-endothelin drug: analysis of 1642 sclerotherapy sessions

    Directory of Open Access Journals (Sweden)

    Alessandro Frullini

    2016-12-01

    Full Text Available In the literature cases of stroke and transient neurological symptoms have been described after sclerotherapy for chronic venous disease The initial interpretation of these phenomena was that of a micro air embolism in association with a patent foramen ovale. This explanation did not always manage to justify all neurological manifestations. Recent theories have demonstrated that in the area of sclerosis, a significant amount of endothelin 1. We carried out a retrospective assessment of sclerotherapy case studies on 540 patients at ten phlebological centres to search for a relationship between the use of aminaftone (a venotropic drug with demonstrated anti-endothelin action and the occurrence of side effects after sclerotherapy was performed. Significant reduction of side effects was observed in sclerotherapy for teleangectasias and in patients with migraine history.

  4. Neuroprotective Effects of Exercise on Brain Edema and Neurological Movement Disorders Following the Cerebral Ischemia and Reperfusion in Rats

    OpenAIRE

    Shamsaei, Nabi; Erfani, Soheila; Fereidoni, Masoud; Shahbazi, Ali

    2017-01-01

    Introduction: Cerebral ischemia and reperfusion causes physiological and biochemical changes in the neuronal cells that will eventually lead to cell damage. Evidence indicates that exercise reduces the ischemia and reperfusion-induced brain damages in animal models of stroke. In the present study, the effect of exercise preconditioning on brain edema and neurological movement disorders following the cerebral ischemia and reperfusion in rats was investigated. Methods: Twenty-one adult male wis...

  5. Air bubble migration is a random event post embryo transfer.

    Science.gov (United States)

    Confino, E; Zhang, J; Risquez, F

    2007-06-01

    Air bubble location following embryo transfer (ET) is the presumable placement spot of embryos. The purpose of this study was to document endometrial air bubble position and migration following embryo transfer. Multicenter prospective case study. Eighty-eight embryo transfers were performed under abdominal ultrasound guidance in two countries by two authors. A single or double air bubble was loaded with the embryos using a soft, coaxial, end opened catheters. The embryos were slowly injected 10-20 mm from the fundus. Air bubble position was recorded immediately, 30 minutes later and when the patient stood up. Bubble marker location analysis revealed a random distribution without visible gravity effect when the patients stood up. The bubble markers demonstrated splitting, moving in all directions and dispersion. Air bubbles move and split frequently post ET with the patient in the horizontal position, suggestive of active uterine contractions. Bubble migration analysis supports a rather random movement of the bubbles and possibly the embryos. Standing up changed somewhat bubble configuration and distribution in the uterine cavity. Gravity related bubble motion was uncommon, suggesting that horizontal rest post ET may not be necessary. This report challenges the common belief that a very accurate ultrasound guided embryo placement is mandatory. The very random bubble movement observed in this two-center study suggests that a large "window" of embryo placement maybe present.

  6. Gas bubble dynamics in soft materials.

    Science.gov (United States)

    Solano-Altamirano, J M; Malcolm, John D; Goldman, Saul

    2015-01-07

    Epstein and Plesset's seminal work on the rate of gas bubble dissolution and growth in a simple liquid is generalized to render it applicable to a gas bubble embedded in a soft elastic solid. Both the underlying diffusion equation and the expression for the gas bubble pressure were modified to allow for the non-zero shear modulus of the medium. The extension of the diffusion equation results in a trivial shift (by an additive constant) in the value of the diffusion coefficient, and does not change the form of the rate equations. But the use of a generalized Young-Laplace equation for the bubble pressure resulted in significant differences on the dynamics of bubble dissolution and growth, relative to an inviscid liquid medium. Depending on whether the salient parameters (solute concentration, initial bubble radius, surface tension, and shear modulus) lead to bubble growth or dissolution, the effect of allowing for a non-zero shear modulus in the generalized Young-Laplace equation is to speed up the rate of bubble growth, or to reduce the rate of bubble dissolution, respectively. The relation to previous work on visco-elastic materials is discussed, as is the connection of this work to the problem of Decompression Sickness (specifically, "the bends"). Examples of tissues to which our expressions can be applied are provided. Also, a new phenomenon is predicted whereby, for some parameter values, a bubble can be metastable and persist for long times, or it may grow, when embedded in a homogeneous under-saturated soft elastic medium.

  7. Pressure waves in a supersaturated bubbly magma

    Science.gov (United States)

    Kurzon, I.; Lyakhovsky, V.; Navon, O.; Chouet, B.

    2011-01-01

    We study the interaction of acoustic pressure waves with an expanding bubbly magma. The expansion of magma is the result of bubble growth during or following magma decompression and leads to two competing processes that affect pressure waves. On the one hand, growth in vesicularity leads to increased damping and decreased wave amplitudes, and on the other hand, a decrease in the effective bulk modulus of the bubbly mixture reduces wave velocity, which in turn, reduces damping and may lead to wave amplification. The additional acoustic energy originates from the chemical energy released during bubble growth. We examine this phenomenon analytically to identify conditions under which amplification of pressure waves is possible. These conditions are further examined numerically to shed light on the frequency and phase dependencies in relation to the interaction of waves and growing bubbles. Amplification is possible at low frequencies and when the growth rate of bubbles reaches an optimum value for which the wave velocity decreases sufficiently to overcome the increased damping of the vesicular material. We examine two amplification phase-dependent effects: (1) a tensile-phase effect in which the inserted wave adds to the process of bubble growth, utilizing the energy associated with the gas overpressure in the bubble and therefore converting a large proportion of this energy into additional acoustic energy, and (2) a compressive-phase effect in which the pressure wave works against the growing bubbles and a large amount of its acoustic energy is dissipated during the first cycle, but later enough energy is gained to amplify the second cycle. These two effects provide additional new possible mechanisms for the amplification phase seen in Long-Period (LP) and Very-Long-Period (VLP) seismic signals originating in magma-filled cracks.

  8. Effects of music and music therapy on mood in neurological patients

    OpenAIRE

    Raglio, Alfredo; Attardo, Lapo; Gontero, Giulia; Rollino, Silvia; Groppo, Elisabetta; Granieri, Enrico

    2015-01-01

    Mood disorder and depressive syndromes represent a common comorbid condition in neurological disorders with a prevalence rate that ranges between 20% and 50% of patients with stroke, epilepsy, multiple sclerosis, and Parkinson’s disease. Notwithstanding, these conditions are often under-diagnosed and under-treated in the clinical practice and negatively affect the functional recovery, the adherence to treatment, the quality of life, and even the mortality risk. In addition, a bidirectional as...

  9. Effects of blood lead level on biochemical and hematological parameters in children with neurological diseases of Western Maharashtra, India.

    Science.gov (United States)

    Pratinidhi, Shilpa A; Patil, Arun J; Behera, Manaskumar; Patil, Maya; Ghadage, Dnyaneshwari P; Pratinidhi, Asha K

    2014-05-01

    Lead is found in small but appreciable quantities in air, soil, drinking water, and food. Exposure to such amounts of lead does not lead to acute lead toxicity but produces subtle effects particularly in children. The aim of this study was to investigate the effects of blood lead level on biochemical and hematological parameters in children with neurological diseases in Western Maharashtra, India, and to estimate the blood lead level by liver and kidney function tests and hematological parameters in children with neurological disorders admitted to the pediatric ward and compare them with healthy controls. In this study, 30 children with various neurological disorders admitted to the pediatric ward of Smt. Kashibai Navale Medical College and General Hospital, Pune, Maharashtra, India, were compared with 30 age- and sex-matched healthy controls. Four milliliters of venous blood was collected for estimation of blood lead level, and biochemical and hematological parameters were determined using standard methods. Blood lead level was significantly increased in the study group (pfood habits and limit hand-to-mouth activities to prevent lead intoxication.

  10. Neuroprotective Effects of Exercise on Brain Edema and Neurological Movement Disorders Following the Cerebral Ischemia and Reperfusion in Rats.

    Science.gov (United States)

    Shamsaei, Nabi; Erfani, Soheila; Fereidoni, Masoud; Shahbazi, Ali

    2017-01-01

    Cerebral ischemia and reperfusion causes physiological and biochemical changes in the neuronal cells that will eventually lead to cell damage. Evidence indicates that exercise reduces the ischemia and reperfusion-induced brain damages in animal models of stroke. In the present study, the effect of exercise preconditioning on brain edema and neurological movement disorders following the cerebral ischemia and reperfusion in rats was investigated. Twenty-one adult male wistar rats (weighing 260-300 g) were randomly divided into three groups: sham operated, exercise plus ischemia, and ischemia group (7 rats per group). The rats in exercise group were trained to run on a treadmill 5 days a week for 4 weeks. Transient focal cerebral ischemia and reperfusion were induced by middle cerebral artery occlusion (MCAO) for 60 minutes, followed by reperfusion for 23 hours. After 24 hours ischemia, movement disorders were tested by a special neurological examination. Also, cerebral edema was assessed by determining the brain water content. The results showed that pre-ischemic exercise significantly reduced brain edema (Pexercise preconditioning decreased the neurological movement disorders caused by brain ischemia and reperfusion (Pexercise had neuroprotective effects against brain ischemia and reperfusion-induced edema and movement disorders. Thus, it could be considered as a useful strategy for prevention of ischemic injuries, especially in people at risk.

  11. Relationship between Liquidity and Price Bubble in Tehran's Asset Market

    Directory of Open Access Journals (Sweden)

    J. Khodaparast SHIRAZI

    2012-12-01

    Full Text Available In this paper, according to Austrian school, the existence of bubbles in asset market of Tehran from 1998 to 2009 is attributed to the unexpected fluctuations of liquidity. To find out the process of bubble, the state space form and Kalman filter are used and bubble is brought out as unobserved variable of price series. In order to determine the long run relationship between liquidity and price bubble the VAR method proposed by Johanson and Jelisus is used. The result confirms that variation of liquidity has a significant effect on the creating of bubble in long run.

  12. The effects of gaseous bubble composition and gap distance on the characteristics of nanosecond discharges in distilled water

    Science.gov (United States)

    Hamdan, Ahmad; Cha, Min Suk

    2016-06-01

    Electric discharge in liquids with bubbles can reduce the energy consumption, which increases treatment efficiency. We present an experimental study of nanosecond discharges in distilled water bubbled with the monoatomic gas argon and with the polyatomic gases methane, carbon dioxide, and propane. We monitor the time evolution of the voltage and current waveforms, and calculate the injected charges to characterize the discharge. We establish a relationship between the injected charges and the shape of the plasma by time-resolved imaging to find that increasing the size of the gap reduces the injected charges. Moreover, we determine the plasma characteristics, including electron density, excitation temperatures (for atoms and ions), and rotational temperature of the OH and C2 radicals found in the plasma. Our space- and time-averaged measurements allow us to propose a spatial distribution of the plasma that is helpful for understanding the plasma dynamics necessary to develop and optimize applications based on nanosecond discharges in bubbled liquids.

  13. Effect of flour minor components on bubble growth in bread dough during proofing assessed by magnetic resonance imaging.

    Science.gov (United States)

    Rouillé, J; Bonny, J-M; Della Valle, G; Devaux, M F; Renou, J P

    2005-05-18

    Fermentation of dough made from standard flour for French breadmaking was followed by nuclear magnetic resonance imaging at 9.4 T. The growth of bubbles (size > 117 microm) was observed for dough density between 0.8 and 0.22 g cm(-3). Cellular structure was assessed by digital image analysis, leading to the definition of fineness and rate of bubble growth. Influence of composition was studied through fractionation by extraction of soluble fractions (6% db), by defatting (soluble fraction increased the dough specific volume and bubble growth rate but decreased fineness, whereas defatting and Pin addition only increased fineness. The role of molecular components of each fraction could be related to dough elongational properties. A final comparison with baking results confirmed that the crumb cellular structure was largely defined after fermentation.

  14. Single bubble sonoluminescence

    NARCIS (Netherlands)

    Brenner, Michael P.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light

  15. Bubbles in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Lin, Jun

    2015-01-01

    Strain-induced deformations in graphene are predicted to give rise to large pseudomagnetic fields. We examine theoretically the case of gas-inflated bubbles to determine whether signatures of such fields are present in the local density of states. Sharp-edged bubbles are found to induce Friedel...

  16. Numerical simulation of high Reynolds number bubble motion

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, J.B. [Clarkson Univ., Potsdam, NY (United States)

    1995-12-31

    This paper presents the results of numerical simulations of bubble motion. All the results are for single bubbles in unbounded fluids. The liquid phase is quiescent except for the motion created by the bubble, which is axisymmetric. The main focus of the paper is on bubbles that are of order 1 mm in diameter in water. Of particular interest is the effect of surfactant molecules on bubble motion. Results for the {open_quotes}insoluble surfactant{close_quotes} model will be presented. These results extend research by other investigators to finite Reynolds numbers. The results indicate that, by assuming complete coverage of the bubble surface, one obtains good agreement with experimental observations of bubble motion in tap water. The effect of surfactant concentration on the separation angle is discussed.

  17. Performance Tests for Bubble Blockage Device

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Kwang Soon; Wi, Kyung Jin; Park, Rae Joon; Wan, Han Seong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Postulated severe core damage accidents have a high threat risk for the safety of human health and jeopardize the environment. Versatile measures have been suggested and applied to mitigate severe accidents in nuclear power plants. To improve the thermal margin for the severe accident measures in high-power reactors, engineered corium cooling systems involving boiling-induced two-phase natural circulation have been proposed for decay heat removal. A boiling-induced natural circulation flow is generated in a coolant path between a hot vessel wall and cold coolant reservoir. In general, it is possible for some bubbles to be entrained in the natural circulation loop. If some bubbles entrain in the liquid phase flow passage, flow instability may occur, that is, the natural circulation mass flow rate may be oscillated. A new device to block the entraining bubbles is proposed and verified using air-water test loop. To avoid bubbles entrained in the natural circulation flow loop, a new device was proposed and verified using an air-water test loop. The air injection and liquid circulation loop was prepared, and the tests for the bubble blockage devices were performed by varying the geometry and shape of the devices. The performance of the bubble blockage device was more effective as the area ratio of the inlet to the down-comer increased, and the device height decreased. If the device has a rim to generate a vortex zone, the bubbles will be most effectively blocked.

  18. Understanding the bubbles

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    that are identified to exist between the Internet and housing market bubbles: uncertainty and sentiments. The iteration between uncertainty and sentiments leads to the emergence of the third commonality: residue. The residue is the difference between the actors’ overall sentiment about exaggerated future prospects......Understanding how and why bubbles occur as well as whether these could be anticipated, managed, or even prevented is equally important as to know how to recover from them. To address these questions, a model of bubble emergence is put forward. The model builds on two fundamental commonalities...... of a new venture and intended outcomes of that new venture; the higher the residue, the higher the likelihood of the bubble emergence; as residue increases, the likelihood of bubble burst increases. One question that arises is whether one can manage the hype, hence the residue. In this, it is maintained...

  19. The rheology of gravity driven bubbly liquids

    Science.gov (United States)

    Martinez-Mercado, Julian; Zenit, Roberto

    2002-11-01

    Experiments on a vertical channel were performed to to study the behavior of a monodispersed bubble suspension. Using water and water-glycerin mixtures, we were able to obtain measurements for a range of Reynolds and Weber numbers. To generate a uniform stream of bubbles an array of identical capillaries was used. To avoid the coalescence effects, a small amount of salt was added to the interstitial fluid, which did not affect the fluid properties significantly. Measurements of the bubble phase velocity were obtained using a dual impedance probe and through high speed digital video processing. We also obtained measurements of the bubble size and shape as a function of the gas volume fraction for the different flow regimes. We found that, for all cases, the bubble velocity decreases as mean gas volume fraction increases. The flow agitation, characterized with the bubble velocity variance, increases with bubble concentration. The flow becomes unstable for lower gas concentrations as the viscosity of the interstitial fluid increases.

  20. Determining the Enthalpy of Vaporization of Salt Solutions Using the Cooling Effect of a Bubble Column Evaporator

    Science.gov (United States)

    Fan, Chao; Pashley, Richard M.

    2016-01-01

    The enthalpy of vaporization (?H[subscript vap]) of salt solutions is not easily measured, as a certain quantity of pure water has to be evaporated from a solution, at constant composition, and at a fixed temperature and pressure; then the corresponding heat input has to be measured. However, a simple bubble column evaporator (BCE) was used as a…

  1. Asymmetric magnetic bubble expansion under in-plane field in Pt/Co/Pt : Effect of interface engineering

    NARCIS (Netherlands)

    Lavrijsen, R.; Hartmann, D. M. F.; van den Brink, Ton; Yin, Y.; Barcones, B.; Duine, R. A.|info:eu-repo/dai/nl/304830127; Verheijen, M. A.; Swagten, H. J. M.; Koopmans, B.

    2015-01-01

    We analyze the impact of growth conditions on the asymmetric magnetic bubble expansion under an in-plane field in ultrathin Pt/Co/Pt films. Specifically, using sputter deposition, we vary the Ar pressure during the growth of the top Pt layer. This induces a large change in the interfacial structure

  2. Bubble-facilitated VOC transport from LNAPL smear zones and its potential effect on vapor intrusion: Laboratory experiments

    Science.gov (United States)

    Soucy, N. C.; Mumford, K. G.

    2016-12-01

    Light non-aqueous phase liquid (LNAPL) sources can pose a significant threat to indoor air through the volatilization of hydrocarbons from the source and the subsequent transport of vapor through the soil. If subjected to the rise and fall of a water table, an LNAPL source can become a smear zone that consists of trapped discontinuous LNAPL blobs (residual) and has a higher aqueous permeability and higher surface area-to-volume ratio than pool sources. The rise and fall of a water table can also trap atmospheric air bubbles alongside the LNAPL. If these bubbles expand and become mobile, either through partitioning of volatile organic compounds (VOCs) or the production of biogenic gases, bubble-facilitated vertical vapor transport can occur. It is important to understand the bubble-facilitated transport of VOCs as it is a mechanism that could lead to faster transport. The transport of VOCs from smear zones was investigated using laboratory column and visualization experiments. In the column experiments, pentane LNAPL was emplaced in a 5 cm sand-packed source zone and the water level was raised and lowered to trap residual LNAPL and air bubbles. Each column also contained a 10 cm-high zone of clean saturated sand, and a 10 cm vadose zone of 4 mm-diameter glass beads. Water was pumped through the source and occlusion zones, and air flowed across the top of the column, where vapor samples were collected and analyzed immediately by gas chromatography. In the visualization experiments, pentane LNAPL was emplaced in a two-dimensional cell designed to allow visualization of mobilized LNAPL and gas through glass walls. Results of the column experiments showed VOC mass fluxes in test columns were 1-2 orders of magnitude greater than in the control columns. In addition, the flux signal was intermittent, consistent with expectations of bubble-facilitated transport. The results from the visualization experiments showed gas fingers growing and mobilizing over time, and supports

  3. Corneal thickness, residual stromal thickness, and its effect on opaque bubble layer in small-incision lenticule extraction.

    Science.gov (United States)

    Ma, Jiaonan; Wang, Yan; Li, Liuyang; Zhang, Jiamei

    2017-08-18

    To evaluate the effects of the central corneal thickness (CCT) and residual stromal thickness (RST) on the formation of opaque bubble layer (OBL) during small-incision lenticule extraction (SMILE). A total of 345 eyes from Refractive Surgery Center database at Tianjin Eye Hospital that had been subjected to SMILE surgery and followed for 6 months were included in this study and divided into OBL and OBL-free groups. Preoperative, intraoperative, and postoperative data for all eyes were evaluated and analyzed using multivariate regression analysis. After adjustment for several confounding factors, potential associations of CCT and RST with OBL were elucidated by determining odds ratios (ORs) and 95% confidence intervals (CIs). In total, 22 of the 345 eyes developed various degrees of OBL during the femtosecond laser scanning phase of SMILE surgery. After adjustment for age, sex, and refractive errors, significant relationships were detected between CCT and RST and OBL formation (OR 1.04; 95% CI 1.02-1.06; OR 1.03; 95% CI 1.02-1.05, respectively, P < 0.001). Smooth curve fitting revealed an increased risk of OBL in the presence of an increased CCT or RST. However, visual outcomes were comparable between the two groups at both 3 and 6 months postoperatively. The results suggest that OBL formation during SMILE surgery is more likely in eyes with a thicker cornea. CCT and RST can be considered independent risk factors for OBL formation. Although this phenomenon may disturb the surgical procedure, it is unlikely to affect the postoperative visual outcome.

  4. Lithotripter shock wave interaction with a bubble near various biomaterials

    Science.gov (United States)

    Ohl, S. W.; Klaseboer, E.; Szeri, A. J.; Khoo, B. C.

    2016-10-01

    Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling shock wave (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter shock wave are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction wave hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the shock wave at the bone—water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (˜1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the shock wave. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a shock wave, and a nearby bio-material.

  5. Experimental investigation of shock wave - bubble interaction

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Mohsen

    2010-04-09

    In this work, the dynamics of laser-generated single cavitation bubbles exposed to lithotripter shock waves has been investigated experimentally. The energy of the impinging shock wave is varied in several steps. High-speed photography and pressure field measurements simultaneously with image acquisition provide the possibility of capturing the fast bubble dynamics under the effect of the shock wave impact. The pressure measurement is performed using a fiber optic probe hydrophone (FOPH) which operates based on optical diagnostics of the shock wave propagating medium. After a short introduction in chapter 1 an overview of the previous studies in chapter 2 is presented. The reported literatures include theoretical and experimental investigations of several configurations of physical problems in the field of bubble dynamics. In chapter 3 a theoretical description of propagation of a shock wave in a liquid like water has been discussed. Different kinds of reflection of a shock wave at an interface are taken into account. Undisturbed bubble dynamics as well as interaction between a planar shock wave and an initially spherical bubble are explored theoretically. Some physical parameters which are important in this issue such as the velocity of the shock-induced liquid jet, Kelvin impulse and kinetic energy are explained. The shock waves are generated in a water filled container by a focusing piezoelectric generator. The shock wave profile has a positive part with pulse duration of ∼1 μs followed by a longer tension tail (i.e. ∼3 μs). In chapter 4 high-speed images depict the propagation of a shock wave in the water filled tank. The maximum pressure is also derived for different intensity levels of the shock wave generator. The measurement is performed in the free field (i.e. in the absence of laser-generated single bubbles). In chapter 5 the interaction between lithotripter shock waves and laserinduced single cavitation bubbles is investigated experimentally. An

  6. The characteristics of a vapour bubble moving in a non-uniform flow field

    Science.gov (United States)

    Hangen, Ni; Jianbo, Huang

    1986-08-01

    The present paper describes the dynamic process of a vapour bubble moving in a non-uniform flow field. The coupling between the bubble moving as a whole and the deformation of the bubble surface is considered. The effect of the pressure gradient on the bubble movement is analysed. For a given flow field the numerical calculation is carried out until the vapour bubble is split by a micro-jet.

  7. Chaotic behavior in bubble formation dynamics

    Science.gov (United States)

    Tufaile, A.; Sartorelli, J. C.

    2000-01-01

    We constructed an experimental apparatus to study the dynamics of the formation of air bubbles in a submerged nozzle in a water/glycerin solution inside a cylindrical tube. The delay time between successive bubbles was measured with a laser-photodiode system. It was observed bifurcations, chaotic behavior, and sudden changes in a periodic regime as a function of the decreasing air pressure in a reservoir. We also observed dynamical effects by applying a sound wave tuned to the fundamental frequency of the air column above the solution. As a function of the sound wave amplitude, we obtained a limit cycle, a flip bifurcation, chaotic behavior, and the synchronization of the bubbling with sound wave frequency. We related some of the different dynamical behaviors to coalescent effects and bubble sizes.

  8. On the shape of giant soap bubbles.

    Science.gov (United States)

    Cohen, Caroline; Darbois Texier, Baptiste; Reyssat, Etienne; Snoeijer, Jacco H; Quéré, David; Clanet, Christophe

    2017-03-07

    We study the effect of gravity on giant soap bubbles and show that it becomes dominant above the critical size [Formula: see text], where [Formula: see text] is the mean thickness of the soap film and [Formula: see text] is the capillary length ([Formula: see text] stands for vapor-liquid surface tension, and [Formula: see text] stands for the liquid density). We first show experimentally that large soap bubbles do not retain a spherical shape but flatten when increasing their size. A theoretical model is then developed to account for this effect, predicting the shape based on mechanical equilibrium. In stark contrast to liquid drops, we show that there is no mechanical limit of the height of giant bubble shapes. In practice, the physicochemical constraints imposed by surfactant molecules limit the access to this large asymptotic domain. However, by an exact analogy, it is shown how the giant bubble shapes can be realized by large inflatable structures.

  9. Bubbles and semi-bubbles as a new kind of superheavy nuclei

    CERN Document Server

    Dechargé, J; Girod, M; Dietrich, K G

    2003-01-01

    Applying the HFB theory with the effective interaction D1S of Gogny, two kinds of 'hyperheavy nuclei' were discovered: true 'bubbles' with practically vanishing nuclear density in the central region of the nucleus, and 'semi-bubbles' ('unsaturated nuclei') with a reduced but finite density near the nuclear center. Semi-bubbles are found to be stable with regard to the emission of a neutron or a proton for nucleon numbers A and charge numbers Z in the ranges 292 < or approx. 750 and 120 < or approx. 240, and true bubbles for 750 < or approx. 920 and 240 < or approx. 280, respectively. For a limited number of nuclear species, a third type of hyperheavy nuclei with a finite, strongly reduced, halo-like central density ('internal halo nuclei') is found. Coexistence of bubble and semi-bubble solutions for given nucleon and charge numbers is frequently obtained, the semi-bubbles being the ground states for A < or approx. 240, and the true bubbles for the heavier nuclear species. The dominant disinteg...

  10. Neurological soft signs: Effects of trait schizotypy, psychological distress and auditory hallucination predisposition

    Directory of Open Access Journals (Sweden)

    Saskia de Leede-Smith

    2017-03-01

    Full Text Available Schizotypy is regarded as a trait vulnerability for psychotic disorders, yet alone is insufficient for development of a diagnosable disorder. Additional symptoms and psychological distress are necessary for help seeking and transition from an at risk mental state to a clinical diagnosis. The present study investigated the interaction between trait schizotypy, state auditory verbal hallucination (AVH predisposition, distress and handedness for the expression of neurological soft signs (NSS, a neurodevelopmental vulnerability factor for psychosis. Cluster analysis formed schizotypy groups statistically across the dimensions captured by the SPQ. It was hypothesized that schizotypy and AVH predisposition would interact, resulting in significantly greater NSS. Psychological distress and handedness were hypothesized to be significant covariates, accounting for some variance in the expression of NSS between the groups. A sample of University students (n = 327 completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, General Health Questionnaire and the Neurological Evaluation Scale (NES. Cluster Analysis revealed four schizotypy groups. Distress was not a significant covariate in any analysis. As expected, those with high overall schizotypy and high AVH predisposition expressed significantly greater Motor-Coordination NSS compared to those with high schizotypy and low AVH predisposition. Within the Mixed Interpersonal and Cognitive-Perceptual Schizotypy cluster, those with low AVH predisposition expressed significantly more Motor-Coordination NSS than those with high AVH predisposition. These findings suggest motor coordination NSS are detectable in schizotypy, and AVH predisposition appears to interact with these traits. This study highlights the importance of considering both trait and subclinical state risk factors when investigating risk for psychosis.

  11. Melt-Bubble Surface Tension in Hydrous Magmas and the Effects of Alkalinity, Temperature, and Water Content

    Science.gov (United States)

    Lewis, A. E.; Gardner, J. E.

    2009-12-01

    Understanding the kinetics and controls on bubble nucleation in hydrous magmas is of fundamental importance to understanding volcanic eruptions. Eruptive style, whether explosive or effusive, may in fact be intrinsically linked to the nature of the nucleation of bubbles in the melt. The most abundant dissolved volatile to form bubbles in magma is H2O. To first order, melt-bubble surface tension (σ) and the supersaturation (ΔP) of water in the melt govern the onset and rate of bubble nucleation, assuming homogenous nucleation. The sensitivity of σ and its ability to significantly impact when nucleation occurs and ΔP warrants closer investigation. From the limited published data gathered, we know that surface tension varies in response to changes in temperature, water content, and melt composition, but their full impact is poorly constrained. For our analysis of σ we focus on the impact of melt composition, and have begun by using a trachytic melt with similar SiO2 content yet elevated alkali contents in comparison to available dacitic melt data (Mangan and Sisson, 2005). We have approached the problem by subjecting the trachyte melt to several hydrothermal decompression experiments at a single water content. We first hydrated the melt at super-liquidus conditions (1050° C and 150 MPa) for 5 days. Fourier transform infrared spectroscopy reveal consistent dissolved water contents of 4.70 (± 0.07) wt.% H2O in all samples. Five decompressions have been executed at 900°C, from the initial pressure of 150 MPa to various lower final pressures corresponding to ΔP values ranging from 94 MPa to 114 MPa. All samples were nearly instantaneously decompressed to the final pressure and held for 60 seconds before being rapidly quenched. Preliminary results tentatively indicate a σ of 0.078 N/m for hydrous trachyte. This value correlates well with the dacitic data, although those experiments were not conducted isothermally, suggesting the greater proportion of alkalis

  12. Chemistry in Soap Bubbles.

    Science.gov (United States)

    Lee, Albert W. M.; Wong, A.; Lee, H. W.; Lee, H. Y.; Zhou, Ning-Huai

    2002-01-01

    Describes a laboratory experiment in which common chemical gases are trapped inside soap bubbles. Examines the physical and chemical properties of the gases such as relative density and combustion. (Author/MM)

  13. Bubble dynamics in DNA

    Energy Technology Data Exchange (ETDEWEB)

    Hanke, Andreas [Institut fuer Theoretische Physik, Universitaet Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart (Germany); Metzler, Ralf [NORDITA-Nordic Institute for Theoretical Physics, Blegdamsvej 17, DK-2100 Copenhagen O (Denmark)

    2003-09-12

    The formation of local denaturation zones (bubbles) in double-stranded DNA is an important example of conformational changes of biological macromolecules. We study the dynamics of bubble formation in terms of a Fokker-Planck equation for the probability density to find a bubble of size n base pairs at time t, on the basis of the free energy in the Poland-Scheraga model. Characteristic bubble closing and opening times can be determined from the corresponding first passage time problem, and are sensitive to the specific parameters entering the model. A multistate unzipping model with constant rates recently applied to DNA breathing dynamics (Altan-Bonnet et al 2003 Phys. Rev. Lett. 90 138101) emerges as a limiting case. (letter to the editor)

  14. Bubble Proliferation in Shock Wave Lithotripsy Occurs during Inertial Collapse

    Science.gov (United States)

    Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Williams, James C.; Bailey, Michael R.; Sapozhnikov, Oleg A.

    2008-06-01

    In shock wave lithotripsy (SWL), firing shock pulses at slow pulse repetition frequency (0.5 Hz) is more effective at breaking kidney stones than firing shock waves (SWs) at fast rate (2 Hz). Since at fast rate the number of cavitation bubbles increases, it appears that bubble proliferation reduces the efficiency of SWL. The goal of this work was to determine the basis for bubble proliferation when SWs are delivered at fast rate. Bubbles were studied using a high-speed camera (Imacon 200). Experiments were conducted in a test tank filled with nondegassed tap water at room temperature. Acoustic pulses were generated with an electromagnetic lithotripter (DoLi-50). In the focus of the lithotripter the pulses consisted of a ˜60 MPa positive-pressure spike followed by up to -8 MPa negative-pressure tail, all with a total duration of about 7 μs. Nonlinear propagation steepened the shock front of the pulses to become sufficiently thin (˜0.03 μm) to impose differential pressure across even microscopic bubbles. High-speed camera movies showed that the SWs forced preexisting microbubbles to collapse, jet, and break up into daughter bubbles, which then grew rapidly under the negative-pressure phase of the pulse, but later coalesced to re-form a single bubble. Subsequent bubble growth was followed by inertial collapse and, usually, rebound. Most, if not all, cavitation bubbles emitted micro-jets during their first inertial collapse and re-growth. After jetting, these rebounding bubbles could regain a spherical shape before undergoing a second inertial collapse. However, either upon this second inertial collapse, or sometimes upon the first inertial collapse, the rebounding bubble emerged from the collapse as a cloud of smaller bubbles rather than a single bubble. These daughter bubbles could continue to rebound and collapse for a few cycles, but did not coalesce. These observations show that the positive-pressure phase of SWs fragments preexisting bubbles but this initial

  15. Effectiveness of music-based interventions on motricity or cognitive functioning in neurological populations: a systematic review.

    Science.gov (United States)

    Moumdjian, Lousin; Sarkamo, Teppo; Leone, Carmela; Leman, Marc; Feys, Peter

    2017-06-01

    Motor and cognitive symptoms are frequent in persons with neurological disorders and often require extensive long-term rehabilitation. Recently, a variety of music-based interventions have been introduced into neurological rehabilitation as training tools. This review aims to 1) describe and define music-based intervention modalities and content which are applied in experimental studies; and 2) describe the effects of these interventions on motor and/or cognitive symptoms in the neurological population. The databases PubMed and Web of Science were searched. Cited references of included articles where screened for potential inclusion. A systematic literature search up to 20th of June 2016 was conducted to include controlled trials and cohort studies that have used music-based interventions for ≥3 weeks in the neurological population (in- and outpatients) targeting motor and/or cognitive symptoms. No limitations to publication date was set. EVIDENCE SYNTHESISː Nineteen articles comprising thirteen randomized controlled trials (total participants Nexp=241, Nctrl=269), four controlled trials (Nexp=59, Nctrl=53) and two cohort studies (N.=27) were included. Fourteen studies were conducted in stroke, three in Parkinson's disease, and two in multiple sclerosis population. Modalities of music-based interventions were clustered into four groups: instrument-based, listening-based, rhythm-based, and multicomponent-based music interventions. Overall, studies consistently showed that music-based interventions had similar or larger effects than conventional rehabilitation on upper limb function (N.=16; fine motricity, hand and arm capacity, finger and hand tapping velocity/variability), mobility (N.=7; gait parameters), and cognition (N.=4; verbal memory and focused attention). CONCLUSIONSː Variety of modalities using music-based interventions has been identified and grouped into four clusters. Effects of interventions demonstrate an improvement in the domains assessed

  16. Bubble Impingement and the Mechanisms of Heat Transfer

    OpenAIRE

    Robinson, Anthony; ALBADAWI, ABDULALEEM; MURRAY, DARINA

    2014-01-01

    PUBLISHED Heat transfer augmentation resulting from the effects of two phase flow can play a significant role in convective cooling applications. To date, the interaction between a rising gas bubble impinging on a heated horizontal surface has received limited attention. Available research has focused on bubble dynamics and the associated heat transfer has not been reported. To address this, this study investigates the effect of a single bubble impinging on a heated horizontal surface. Loc...

  17. Flow field from transient bubble oscillation in a narrow gap: numerical simulations and effect on biological cells

    CERN Document Server

    Mohammadzadeh, Milad; Ohl, Claus-Dieter

    2016-01-01

    The flow driven by a rapidly expanding and collapsing cavitation bubble in a narrow cylindrical gap is studied with the volume of fluid method. The simulations reveal a developing plug flow during the early expansion followed by flow reversal at later stages. An adverse pressure gradient leads to boundary layer separation and flow reversal, causing large shear stress near the boundaries. Analytical solution to a planar pulsating flow shows qualitative agreement with the CFD results. The shear stress close to boundaries has implications to deformable objects located near the bubble: experiments reveal that thin, flat biological cells entrained in the boundary layer become stretched, while cells with a larger cross-section are mainly transported with the flow.

  18. Fluid dynamics of bubbles in liquid

    Directory of Open Access Journals (Sweden)

    C.M. SCHEID

    1999-12-01

    Full Text Available Results gathered from the literature on the dynamics of bubbles in liquid are correlated by means of a formulation traditionally employed to describe the dynamics of isometric solid particles. It is assumed that the shape of the bubble depends, by means of the Eotvos number, on its diameter and on the gas-liquid surface tension. The analysis reported herein includes the dynamics of the isolated bubble along with wall and concentration effects. However, the effects of gas circulation in the bubble, which result in terminal velocities higher than those of a rigid sphere, are not being considered. A limited number of experimental points are obtained employing a modified version of the Mariotte flask which permits the precise measure of bubble volume. A classic bubble column is also employed in order to measure gas holdup in the continuous phase. Experiments were carried out employing air, with distilled water, potable water, water with variable amounts of surfactant and glycerin as the liquid phase.

  19. Double pulse laser induced breakdown spectroscopy of a solid in water: Effect of hydrostatic pressure on laser induced plasma, cavitation bubble and emission spectra

    Science.gov (United States)

    López-Claros, M.; Dell'Aglio, M.; Gaudiuso, R.; Santagata, A.; De Giacomo, A.; Fortes, F. J.; Laserna, J. J.

    2017-07-01

    There is a growing interest in the development of sensors use in exploration of the deep ocean. Techniques for the chemical analysis of submerged solids are of special interest, as they show promise for subsea mining applications where a rapid sorting of materials found in the sea bottom would improve efficiency. Laser-Induced Breakdown Spectroscopy (LIBS) has demonstrated potential for this application thanks to its unique capability of providing the atomic composition of submerged solids. Here we present a study on the parameters that affect the spectral response of metallic targets in an oceanic pressure environment. Following laser excitation of the solid, the plasma persistence and the cavitation bubble size are considerably reduced as the hydrostatic pressure increases. These effects are of particular concern in dual pulse excitation as reported here, where a careful choice of the interpulse timing is required. Shadowgraphic images of the plasma demonstrate that cavitation bubbles are formed early after the plasma onset and that the effect of hydrostatic pressure is negligible during the early stage of plasma expansion. Contrarily to what is observed at atmospheric pressure, emission spectra observed at high pressures are characterized by self-absorbed atomic lines on continuum radiation resulting from strong radiative recombination in the electron-rich confined environment. This effect is much less evident with ionic lines due to the much higher energy of the levels involved and ionization energy of ions, as well as to the lower extent of absorption effects occurring in the inner part of the plasma, where ionized species are more abundant. As a result of the smaller shorter-lived cavitation bubble, the LIBS intensity enhancement resulting from dual pulse excitation is reduced when the applied pressure increases.

  20. Effect of neurological symptoms on the course and the healing of fractures of the mandible

    Directory of Open Access Journals (Sweden)

    Muhina N.M.

    2012-06-01

    Full Text Available

    Purpose: to study the dental status and neurological symptoms in patients with fractures of the mandible for improving diagnosis, predicting the course of reparative processes and the application of preventive measures of infam-matory complications. Material. We observed 132 patients with mandibular fractures of different location, the hospital received no later than 3 days after injury and comparison group, consisting of 15 healthy people. Dental status of patients included clinical examination: identifying reasons for injuries, complaints external examination of maxillofacial area. Assessment of pain that was observed in patients in the area of innervation of the trigeminal nerve, was carried out using a scale for measuring the intensity of pain and need for analgesics (Lantsev EA, AA Smirnov, 1990. Zone of hypesthesia and hyperesthesia were detected in patients in the study of the surface (pain, temperature and tactile and the deep sensitivity of the skin. State of the motor portion of the third branch of the trigeminal nerve was assessed by palpation of masticatory and temporal muscles, according to electromyographic, in the late periods of the presence of atrophy of the masticatory muscles on the affected side and disturbance trajectory of the mandible. In addition, elec-trophysiological examination included registration of trigeminal somatosensory evoked potentials. The study of pain sensitivity of the teeth was carried out using a digital tester to determine the viability of the pulp «Digitest». This study was conducted on the day of admission and on the 10th day of treatment. Results. Clinical and instrumental evaluation of patients with uncomplicated fractures of the mandibular nerve fber damage detected in 100 % of cases. In complicated fractures clinically identifed sensory disorders paresteticheskih signs of interest in the trigeminal nerve were found in 51.8 % of cases. In

  1. Electroacupuncture effect on neurological behavior and tyrosine kinase-JAK 2 in rats with focal cerebral ischemia.

    Science.gov (United States)

    Liu, Rong; Xu, Nenggui; Yi, Wei; Huang, Kangbai; Su, Minzhi

    2012-09-01

    Electroacupuncture effect on neurological behavior and the expression of tyrosine kinase Janus kinase 2 (JAK 2) of ischemic cortex in rats with the focal cerebral ischemia were investigated in this study. The model of focal cerebral ischemia was established by the heat-coagulation induced the occlusion of the middle cerebral artery. The electro-acupuncture was applied on Baihui (GV 20) and Dazhui (GV 14), and AG490 was applied by intracerebroventricular infusion. The expressions of JAK2 mRNA and phospharylated JAK2 (p-JAK2) in the ischemic cortex were observed by in situ hybridization and western blotting. The expressions of JAK2 mRNA and p-JAK2 were rarely found in sham surgery group. In model group, the expression of JAK2 mRNA and JAK2 phosphorylation had increased. After 1 day of cerebral ischemia, the expression had reached its peak. After cerebral ischemia, the expressions of JAK2 mRNA and p-JAK2 were consistent with the neurological deficit score. Electroacupuncture treatment and AG490 intervention were able to improve the neurological deficit score after cerebral ischemia, and down-regulate the expressions of JAK2 mRNA and JAK2 phosphorylation. After cerebral ischemia, the excessive expressions of JAK2 and the JAK2 phosphorylation would be one of mechanisms by which the brain injury got worse. The therapy of electro-acupuncture could reduce the expression of JAK2, and inhibit JAK2 phosphorylated activation, so as to block the abnormal activation of signal transduction pathway which was induced by JAK2.

  2. The effects of gaseous bubble composition and gap distance on the characteristics of nanosecond discharges in distilled water

    KAUST Repository

    Hamdan, Ahmad

    2016-05-17

    Electric discharge in liquids with bubbles can reduce the energy consumption, which increases treatment efficiency. We present an experimental study of nanosecond discharges in distilled water bubbled with the monoatomic gas argon and with the polyatomic gases methane, carbon dioxide, and propane. We monitor the time evolution of the voltage and current waveforms, and calculate the injected charges to characterize the discharge. We establish a relationship between the injected charges and the shape of the plasma by time-resolved imaging to find that increasing the size of the gap reduces the injected charges. Moreover, we determine the plasma characteristics, including electron density, excitation temperatures (for atoms and ions), and rotational temperature of the OH and C2 radicals found in the plasma. Our space- and time-averaged measurements allow us to propose a spatial distribution of the plasma that is helpful for understanding the plasma dynamics necessary to develop and optimize applications based on nanosecond discharges in bubbled liquids. © 2016 IOP Publishing Ltd.

  3. Effects of peer-assisted training during the neurology clerkship: a randomized controlled study.

    Science.gov (United States)

    Heckmann, J G; Dütsch, M; Rauch, C; Lang, C; Weih, M; Schwab, S

    2008-12-01

    To determine the efficacy of peer-assisted clinical skills training for students during their neurology clerkship. Students (n = 122) were randomized to get clinical skills training from either student (peer) instructors (experimental group) or from experienced clinical staff (control group). The remaining schedule during the clerkship did not differ between both groups. Primary endpoint was students' practical skills and knowledge tested at the end of the course by a written test and objective structured clinical examination (OSCE). Secondary endpoints were evaluation of the practical training and self-estimated gain in theoretical and practical competence. In the written test, the peer-trained group (n = 66) scored 69.5 +/- 10.2 (95% CI 67-72) points of 100 and the postgraduates-trained group (n = 56) 66.7 +/- 11.4 (95% CI 63.6-69.8) (P = 0.15). In the OSCE the peer-trained group scored 93.7 +/- 6.3 (95% CI 92.1 to 95.2) points of 100 and the postgraduates-trained group 92 +/- 5.1 (95% CI 90.6 to 93.4) (P = 0.11). In the evaluation and self-assessment items, there was no significant difference between the two groups except for the postgraduates' higher competence (P = 0.004). Peer-trained students pass written exam and OSCE as efficient as postgraduates-trained students. Self-assessed learning success is equally rated in both groups.

  4. Vaccination and neurological disorders

    Directory of Open Access Journals (Sweden)

    Anastasia Gkampeta

    2015-12-01

    Full Text Available Active immunization of children has been proven very effective in elimination of life threatening complications of many infectious diseases in developed countries. However, as vaccination-preventable infectious diseases and their complications have become rare, the interest focuses on immunization-related adverse reactions. Unfortunately, fear of vaccination-related adverse effects can led to decreased vaccination coverage and subsequent epidemics of infectious diseases. This review includes reports about possible side effects following vaccinations in children with neurological disorders and also published recommendations about vaccinating children with neurological disorders. From all international published data anyone can conclude that vaccines are safer than ever before, but the challenge remains to convey this message to society.

  5. Bubble capture by a propeller

    Science.gov (United States)

    Caillé, François; Clanet, Christophe; Magnaudet, Jacques

    2006-08-01

    A small air bubble (radius a) is injected in water (kinematic viscosity nu) in the vicinity (distance r_0) of a propeller (radius r_p, angular frequency omega). We study experimentally and theoretically the conditions under which the bubble can be ‘captured’, i.e. deviated from its vertical trajectory (imposed by gravity g) and moved toward the centre of the propeller (r {=} 0). We show that the capture frequency omega_{scriptsizecapt} follows the relationship [omega_{hboxriptsizeit capt}=left(frac{2ga^2}{9betanu r_p f(hboxRe_b)}right)left(frac{r_0}{r_p}right)^2(1+\\cos\\varphi_0),] where beta is a dimensionless parameter characterizing the propeller, f(Re_b) is an empirical correction to Stokes' drag law which accounts for finite-Reynolds-number effects and pi/2-varphi_0 is the angle between the axis of the propeller and the line between the centre of the propeller and the point where the bubble is injected. This law is found to be valid as long as the distance d between the propeller and the water surface is larger than 3r_0. For smaller distances, the capture frequency increases; using an image technique, we show how the above expression is modified by the presence of the surface.

  6. Advocacy in neurology

    National Research Council Canada - National Science Library

    Pauranik, Apoorva

    2008-01-01

    ...), launched the Neurological Alliance of Ireland, a nationwide coalition of patient advocacy groups and physicians and authored Standards of Care, the "blueprint" for the development of neurological...

  7. The neurological effects of prenatal and postnatal mercury/methylmercury exposure on three-year-old children in Taiwan.

    Science.gov (United States)

    Hsi, Hsing-Cheng; Jiang, Chuen-Bin; Yang, Tzu-Hsuan; Chien, Ling-Chu

    2014-04-01

    This study attempts to elucidate the relationship between neurological effects and mercury/methylmercury concentrations in various biomarkers, including meconium, hair, fingernail, and toenail. Eight-three mother-infant pairs were recruited between August 2008 and December 2009, and follow-up examinations on these children were completed after three years. The Bayley Scales of Infant and Toddler Development (Bayley-III) for evaluating the cognitive, language, and motor development of three-year-old children were calculated and validated. The geometric mean of the total mercury concentration in meconium was 89.6 ng g(-1). The methylmercury concentrations in hair, fingernail, and toenail samples were 1.96, 0.64, and 0.55 μg g(-1), respectively. Seventy percent of children had hair methylmercury concentrations exceeding the U.S. environmental protection agency (EPA) reference of 1 μg g(-1). A significantly positive correlation was obtained between methylmercury levels in hair, fingernail, and toenail. These methylmercury levels were also significantly positively correlated with the children's fish intake and negatively correlated with a Bayley-III scale score of expressive language. The prenatal mercury exposure, however, did not show significant influence on neurological development. High fish consumption appears to be a critical risk factor for methylmercury levels in children and may cause a lower expressive language score. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Effects of professional rehabilitation training on the recovery of neurological function in young stroke patients

    Directory of Open Access Journals (Sweden)

    Chao-jin-zi Li

    2016-01-01

    Full Text Available Young stroke patients have a strong desire to return to the society, but few studies have been conducted on their rehabilitation training items, intensity, and prognosis. We analyzed clinical data of young and middle-aged/older stroke patients hospitalized in the Department of Neurological Rehabilitation, China Rehabilitation Research Center, Capital Medical University, China from February 2014 to May 2015. Results demonstrated that hemorrhagic stroke (59.6% was the primary stroke type found in the young group, while ischemic stroke (60.0% was the main type detected in the middle-aged/older group. Compared with older stroke patients, education level and incidence of hyperhomocysteinemia were higher in younger stroke patients, whereas, incidences of hypertension, diabetes, and heart disease were lower. The average length of hospital stay was longer in the young group than in the middle-aged/older group. The main risk factors observed in the young stroke patients were hypertension, drinking, smoking, hyperlipidemia, hyperhomocysteinemia, diabetes, previous history of stroke, and heart disease. The most accepted rehabilitation program consisted of physiotherapy, occupational therapy, speech therapy, acupuncture and moxibustion. Average rehabilitation training time was 2.5 hours/day. Barthel Index and modified Rankin Scale scores were increased at discharge. Six months after discharge, the degree of occupational and economic satisfaction declined, and there were no changes in family life satisfaction. The degrees of other life satisfaction (such as friendship improved. The degree of disability and functional status improved significantly in young stroke patients after professional rehabilitation, but the number of patients who returned to society within 6 months after stroke was still small.

  9. Dynamics of bubble rising at small Reynolds numbers

    Directory of Open Access Journals (Sweden)

    Arkhipov Vladimir

    2015-01-01

    Full Text Available Results of experimental study of a single spherical bubble rising in the non-stationary regime in a viscous liquid (with and without surfactant at small Reynolds numbers Re<1 have been presented. Improved empirical correlations for drag coefficient of the bubble rising with and without surfactant in the stationary regime have been obtained. Influence of nonstationary effects on the dynamics of bubble rising has been analyzed.

  10. Migration of clean and contaminated bubbles near a vertical wall

    Science.gov (United States)

    Magnaudet, Jacques; Takemura, Fumio

    2003-11-01

    The lateral migration of air bubbles rising near a vertical wall in both tap water and low-viscosity silicone oil is studied experimentally over a range of Reynolds number (Re) from 10 to 100. Bubbles rising in water behave as rigid spheres and are repelled from the wall whatever Re, owing to the interaction between the defect flow in their wake and the wall. For such bubbles, the lateral force is correctly predicted by a generalization of the Vasseur & Cox's expression, provided a suitable rescaling taking into account the strength of the vorticity at the bubble surface is introduced. Bubbles rising in silicone oil are hydrodynamically clean and are also repelled from the wall for Re less than 35. In contrast they migrate towards the wall at higher Re, due to the Bernoulli effect predicted by potential flow theory. Knowing the strength of the irrotational dipole associated with the bubble and that of the vorticity at its surface as a function of Re, a unified model predicting the sign reversal of the lateral force is obtained by combining linearly the wake-induced effect and the irrotational mechanism. When bubbles rise very close to the wall, a lubrication effect takes place in the gap, resulting in a repulsive force for small separations. This effect makes the sign of the lateral force acting on high-Re clean bubbles change very close to the wall, which result in the bounce of the bubbles.

  11. Effect of oxygen breathing on micro oxygen bubbles in nitrogen-depleted rat adipose tissue at sea level and 25 kPa altitude exposures

    DEFF Research Database (Denmark)

    Randsoe, Thomas; Hyldegaard, Ole

    2012-01-01

    The standard treatment of altitude decompression sickness (aDCS) caused by nitrogen bubble formation is oxygen breathing and recompression. However, micro air bubbles (containing 79% nitrogen), injected into adipose tissue, grow and stabilize at 25 kPa regardless of continued oxygen breathing...... and the tissue nitrogen pressure. To quantify the contribution of oxygen to bubble growth at altitude, micro oxygen bubbles (containing 0% nitrogen) were injected into the adipose tissue of rats depleted from nitrogen by means of preoxygenation (fraction of inspired oxygen = 1.0; 100%) and the bubbles studied...... at 101.3 kPa (sea level) or at 25 kPa altitude exposures during continued oxygen breathing. In keeping with previous observations and bubble kinetic models, we hypothesize that oxygen breathing may contribute to oxygen bubble growth at altitude. Anesthetized rats were exposed to 3 h of oxygen...

  12. Colliding with a crunching bubble

    Energy Technology Data Exchange (ETDEWEB)

    Freivogel, Ben; Freivogel, Ben; Horowitz, Gary T.; Shenker, Stephen

    2007-03-26

    In the context of eternal inflation we discuss the fate of Lambda = 0 bubbles when they collide with Lambda< 0 crunching bubbles. When the Lambda = 0 bubble is supersymmetric, it is not completely destroyed by collisions. If the domain wall separating the bubbles has higher tension than the BPS bound, it is expelled from the Lambda = 0 bubble and does not alter its long time behavior. If the domain wall saturates the BPS bound, then it stays inside the Lambda = 0 bubble and removes a finite fraction of future infinity. In this case, the crunch singularity is hidden behind the horizon of a stable hyperbolic black hole.

  13. Neurologic manifestations of hypothyroidism in dogs.

    Science.gov (United States)

    Bertalan, Abigail; Kent, Marc; Glass, Eric

    2013-03-01

    Hypothyroidism is a common endocrine disease in dogs. A variety of clinicopathologic abnormalities may be present; however, neurologic deficits are rare. In some instances, neurologic deficits may be the sole manifestation of hypothyroidism. Consequent ly, the diagnosis and management of the neurologic disorders associated with hypothyroidism can be challenging. This article describes several neurologic manifestations of primary hypothyroidism in dogs; discusses the pathophysiology of hypothyroidism-induced neurologic disorders affecting the peripheral and central nervous systems; and reviews the evidence for the neurologic effects of hypothyroidism.

  14. A Bubble Bursts

    Science.gov (United States)

    2005-01-01

    RCW 79 is seen in the southern Milky Way, 17,200 light-years from Earth in the constellation Centaurus. The bubble is 70-light years in diameter, and probably took about one million years to form from the radiation and winds of hot young stars. The balloon of gas and dust is an example of stimulated star formation. Such stars are born when the hot bubble expands into the interstellar gas and dust around it. RCW 79 has spawned at least two groups of new stars along the edge of the large bubble. Some are visible inside the small bubble in the lower left corner. Another group of baby stars appears near the opening at the top. NASA's Spitzer Space Telescope easily detects infrared light from the dust particles in RCW 79. The young stars within RCW 79 radiate ultraviolet light that excites molecules of dust within the bubble. This causes the dust grains to emit infrared light that is detected by Spitzer and seen here as the extended red features.

  15. The Effectiveness of Distraction (Cartoon-Patterned Clothes and Bubble-Blowing) on Pain and Anxiety in Preschool Children during Venipuncture in the Emergency Department.

    Science.gov (United States)

    Lilik Lestari, Made Pande; Wanda, Dessie; Hayati, Happy

    2017-01-01

    In preschool children, venipuncture is considered a bodily threat that can cause pain and anxiety, as well as being a traumatic experience. If the pain and anxiety felt by a child during a venipuncture is not addressed properly, it can result in a traumatic experience, and traumatic events in childhood can have long-term consequences. Atraumatic treatment in the emergency department has been little explored in previous research; therefore, the present study assessed the effectiveness of using the distractions of cartoon-patterned clothes and bubble-blowing on the pain and anxiety of preschool children during venipuncture in the emergency department. This was a quasi-experiment that used a post-test only, control group design approach. The sample consisted of 57 preschool children who were due to undergo venipuncture and who were divided into 3 intervention groups. The results showed that distraction using bubble-blowing is effective in reducing pain and anxiety during venipuncture, while cartoon-patterned clothing is only effective in reducing anxiety. Distractions can refocus the attention of a child away from pain and anxiety during venipuncture. It can inhibit the transmission of pain impulses, such that these impulses are not transmitted to the brain. As a result, the sensation of pain is not experienced.

  16. Bubble-Induced Endothelial Microparticles Promote Endothelial Dysfunction.

    Science.gov (United States)

    Yu, Xuhua; Xu, Jiajun; Huang, Guoyang; Zhang, Kun; Qing, Long; Liu, Wenwu; Xu, Weigang

    2017-01-01

    Decompression sickness is a systemic pathophysiological process caused by bubbles and endothelial microparticles (EMPs) are established markers reflecting competency of endothelial function and vascular biology. Here, we investigated the effects of bubble-induced EMPs on endothelial cells in vitro and vivo. Rat pulmonary microvascular endothelial cells (PMVECs) were isolated and stimulated by bubbles and bubble-induced EMPs were collected and incubated with normal PMVECs in vitro. Cell viability and apoptosis were detected using Cell Counting Kit-8 assay and Annexin V FITC/PI double staining, respectively. Cell permeability and pro-inflammatory cytokines were determined by electric cell substrate impedance sensing and enzyme-linked immunosorbent assay, respectively. Intracellular nitric oxide and reactive oxygen species production were analyzed microscopically. In vivo study, bubble-induced EMPs were intravenously injected to the rats and soluble thrombomodulin, intercellular adhesion molecule 1, and vascullar adhesion molecule 1 were involved in evaluating endothelial dysfunction. In our study, bubble stimulus resulted in a significant increase of EMPs release by 3 fold. Bubble-induced EMPs significantly decreased cell viability and increased cell apoptosis. Moreover, bubble-induced EMPs induced abnormal increase of cell permeability and over-expression of pro-inflammatory cytokines. Intracellular ROS production increased while NO production decreased. These negative effects caused by bubble-induced EMPs were remarkably suppressed when EMPs pretreated with surfactant FSN-100. Finally, intravenous injection of bubble-induced EMPs caused elevations of soluble thrombomodulin and pro-inflammatory cytokines in the circulation. Altogether, our results demonstrated that bubble-induced EMPs can mediate endothelial dysfunction in vitro and vivo, which can be attenuated by EMPs abatement strategy. These data expanded our horizon of the detrimental effects of bubble

  17. Bubble-Induced Endothelial Microparticles Promote Endothelial Dysfunction.

    Directory of Open Access Journals (Sweden)

    Xuhua Yu

    Full Text Available Decompression sickness is a systemic pathophysiological process caused by bubbles and endothelial microparticles (EMPs are established markers reflecting competency of endothelial function and vascular biology. Here, we investigated the effects of bubble-induced EMPs on endothelial cells in vitro and vivo. Rat pulmonary microvascular endothelial cells (PMVECs were isolated and stimulated by bubbles and bubble-induced EMPs were collected and incubated with normal PMVECs in vitro. Cell viability and apoptosis were detected using Cell Counting Kit-8 assay and Annexin V FITC/PI double staining, respectively. Cell permeability and pro-inflammatory cytokines were determined by electric cell substrate impedance sensing and enzyme-linked immunosorbent assay, respectively. Intracellular nitric oxide and reactive oxygen species production were analyzed microscopically. In vivo study, bubble-induced EMPs were intravenously injected to the rats and soluble thrombomodulin, intercellular adhesion molecule 1, and vascullar adhesion molecule 1 were involved in evaluating endothelial dysfunction. In our study, bubble stimulus resulted in a significant increase of EMPs release by 3 fold. Bubble-induced EMPs significantly decreased cell viability and increased cell apoptosis. Moreover, bubble-induced EMPs induced abnormal increase of cell permeability and over-expression of pro-inflammatory cytokines. Intracellular ROS production increased while NO production decreased. These negative effects caused by bubble-induced EMPs were remarkably suppressed when EMPs pretreated with surfactant FSN-100. Finally, intravenous injection of bubble-induced EMPs caused elevations of soluble thrombomodulin and pro-inflammatory cytokines in the circulation. Altogether, our results demonstrated that bubble-induced EMPs can mediate endothelial dysfunction in vitro and vivo, which can be attenuated by EMPs abatement strategy. These data expanded our horizon of the detrimental effects

  18. A Study of Drag Force in Isothermal Bubbly Flow

    Directory of Open Access Journals (Sweden)

    C. Li

    2009-12-01

    Full Text Available Driven by the extensive demands of simulating highly concentrated gas bubbly flows in many engineering fields, numerical studies have been performed to investigate the neighbouring effect of a swarm of bubbles on the interfacial drag forces. In this study, a novel drag coefficient correlation (Simonnet et al., 2007 in terms of local void fraction coupled with the population balance model based on average bubble number density (ABND has been implemented and compared with Ishii-Zuber densely distributed fluid particles drag model. The predicted local radial distributions of three primitive variables: gas void fraction, Sauter mean bubble diameter, and gas velocity, are validated against the experimental data of Hibiki et al. (2001. In general, satisfactory agreements between predicted and measured results are achieved by both drag force models. With additional consideration for closely packed bubbles, the latest coefficient model by Simonnet et al. (2007 shows considerably better performance in capturing the reduction of drag forces incurred by neighbouring bubbles.

  19. Dose-effect relationships between manganese exposure and neurological, neuropsychological and pulmonary function in confined space bridge welders.

    Science.gov (United States)

    Bowler, Rosemarie M; Roels, Harry A; Nakagawa, Sanae; Drezgic, Marija; Diamond, Emily; Park, Robert; Koller, William; Bowler, Russell P; Mergler, Donna; Bouchard, Maryse; Smith, Donald; Gwiazda, Roberto; Doty, Richard L

    2007-03-01

    Although adverse neuropsychological and neurological health effects are well known among workers with high manganese (Mn) exposures in mining, ore-processing and ferroalloy production, the risks among welders with lower exposures are less well understood. Confined space welding in construction of a new span of the San Francisco-Oakland Bay Bridge without adequate protection was studied using a multidisciplinary method to identify the dose-effect relationship between adverse health effects and Mn in air or whole blood. Bridge welders (n = 43) with little or no personal protection equipment and exposed to a welding fume containing Mn, were administered neurological, neuropsychological, neurophysiological and pulmonary tests. Outcome variables were analysed in relation to whole blood Mn (MnB) and a Cumulative Exposure Index (CEI) based on Mn-air, duration and type of welding. Welders performed a mean of 16.5 months of welding on the bridge, were on average 43.8 years of age and had on average 12.6 years of education. The mean time weighted average of Mn-air ranged from 0.11-0.46 mg/m(3) (55% >0.20 mg/m(3)). MnB >10 microg/l was found in 43% of the workers, but the concentrations of Mn in urine, lead in blood and copper and iron in plasma were normal. Forced expiratory volume at 1s: forced vital capacity ratios (FEV(1)/FVC) were found to be abnormal in 33.3% of the welders after about 1.5 years of welding at the bridge. Mean scores of bradykinesia and Unified Parkinson Disease Rating Scale exceeded 4 and 6, respectively. Computer assisted tremor analysis system hand tremor and body sway tests, and University of Pennsylvania Smell Identification Test showed impairment in 38.5/61.5, 51.4 and 88% of the welders, respectively. Significant inverse dose-effect relationships with CEI and/or MnB were found for IQ (p

  20. Dose–effect relationships between manganese exposure and neurological, neuropsychological and pulmonary function in confined space bridge welders

    Science.gov (United States)

    Bowler, Rosemarie M; Roels, Harry A; Nakagawa, Sanae; Drezgic, Marija; Diamond, Emily; Park, Robert; Koller, William; Bowler, Russell P; Mergler, Donna; Bouchard, Maryse; Smith, Donald; Gwiazda, Roberto; Doty, Richard L

    2007-01-01

    Background Although adverse neuropsychological and neurological health effects are well known among workers with high manganese (Mn) exposures in mining, ore‐processing and ferroalloy production, the risks among welders with lower exposures are less well understood. Methods Confined space welding in construction of a new span of the San Francisco–Oakland Bay Bridge without adequate protection was studied using a multidisciplinary method to identify the dose–effect relationship between adverse health effects and Mn in air or whole blood. Bridge welders (n = 43) with little or no personal protection equipment and exposed to a welding fume containing Mn, were administered neurological, neuropsychological, neurophysiological and pulmonary tests. Outcome variables were analysed in relation to whole blood Mn (MnB) and a Cumulative Exposure Index (CEI) based on Mn‐air, duration and type of welding. Welders performed a mean of 16.5 months of welding on the bridge, were on average 43.8 years of age and had on average 12.6 years of education. Results The mean time weighted average of Mn‐air ranged from 0.11–0.46 mg/m3 (55% >0.20 mg/m3). MnB >10 µg/l was found in 43% of the workers, but the concentrations of Mn in urine, lead in blood and copper and iron in plasma were normal. Forced expiratory volume at 1s: forced vital capacity ratios (FEV1/FVC) were found to be abnormal in 33.3% of the welders after about 1.5 years of welding at the bridge. Mean scores of bradykinesia and Unified Parkinson Disease Rating Scale exceeded 4 and 6, respectively. Computer assisted tremor analysis system hand tremor and body sway tests, and University of Pennsylvania Smell Identification Test showed impairment in 38.5/61.5, 51.4 and 88% of the welders, respectively. Significant inverse dose–effect relationships with CEI and/or MnB were found for IQ (p⩽0.05), executive function (p⩽0.03), sustaining concentration and sequencing (p⩽0.04), verbal learning (p

  1. Thermocapillary convection around gas bubbles: an important natural effect for the enhancement of heat transfer in liquids under microgravity.

    Science.gov (United States)

    Betz, J; Straub, J

    2002-10-01

    In the presence of a temperature gradient at a liquid-gas or liquid-liquid interface, thermocapillary or Marangoni convection develops. This convection is a special type of natural convection that was not paid much attention in heat transfer for a long time, although it is strong enough to drive liquids against the direction of buoyancy on Earth. In a microgravity environment, however, it is the remaining mode of natural convection and supports heat and mass transfer. During boiling in microgravity it was observed at subcooled liquid conditions. Therefore, the question arises about its contribution to heat transfer without phase change. Thermocapillary convection was quantitatively studied at single gas bubbles in various liquids, both experimentally and numerically. A two-dimensional mathematical model described in this article was developed. The coupled mechanism of heat transfer and fluid flow in pure liquids around a single gas bubble was simulated with a control-volume FE-method. The simulation was accompanied and compared with experiments on Earth. The numerical results are in good accordance with the experiments performed on Earth at various Marangoni numbers using various alcohols of varying chain length and Prandtl numbers. As well as calculations on Earth, the numerical method also allows simulations at stationary spherical gas bubbles in a microgravity environment. The results demonstrate that thermocapillary convection is a natural heat transfer mechanism that can partially replace the buoyancy in a microgravity environment, if extreme precautions are taken concerning the purity of the liquids, because impurities accumulate predominantly at the interface. Under Earth conditions, an enhancement of the heat transfer in a liquid volume is even found in the case where thermocapillary flow is counteracted by buoyancy. In particular, the obstructing influence of surface active substances could be observed during the experiments on Earth in water and also in

  2. The effect of organic matter on CCN properties of particles produced in laboratory simulations of bubble bursting

    Science.gov (United States)

    King, S.; Rosenoern, T.; Nilsson, D.; Bilde, M.

    2010-12-01

    In this study, we measure the submicron size distributions and cloud condensation nucleus properties of aerosol particles produced from a laboratory system that simulates particle formation from bubble bursting. The experimental method consists of a plunging water jet into a stainless steel tank filled with 10 L of artificial seawater, with and without added organic compounds. The tank is equipped with a water pump that can be set at variable speeds. Preliminary results from size distribution measurements agree with previous studies, in that the number concentration and size of particles produced depend on the water jet flux. Observations of cloud condensation nucleus (CCN) activity are also affected by the water pump speed. The CCN activity of artificial seawater, at a salinity of 35‰ and with no added organic compounds, is similar to that of pure sodium chloride. Addition of as much as 1 g/L of D-mannitol does not considerably alter the particle size distribution, nor does it alter the observed CCN activity. Addition of less than 5 mg/L of the surfactant sodium dodecyl sulfate leads to shifts in size distribution roughly similar to those from published results, in which other methods of simulating bubble bursting were used. The growing use of experimental methods for the reproduction of bubble bursting in aerosol laboratories gives us reason to explore possible differences in the properties of particles generated from similar systems. Comparisons between observations from the above-mentioned 10-L tank and those from a larger tank filled with approximately 100 L of identical artificial seawater will also be presented.

  3. Bubble nuclei; Noyaux Bulles

    Energy Technology Data Exchange (ETDEWEB)

    Legoll, F. [Service de Physique Theorique, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1998-07-22

    For nuclei with very high electrical charge, the Coulomb field is expected to drive the protons away from the centre to the surface of the nucleus. Such a nucleus would be no more compact but look like a bubble. The goal of this work is to confirm this idea. We are interested in only the ground state of spherical nuclei. We use the Skyrme potential with the Sly4 parametrization to calculate the mean-field Hamiltonian. Paring correlations are described by a surface-active delta paring interaction. In its ground state the nucleus {sup A=900} X{sub Z=274} is shown to be a bubble. Another stable state is found with a little higher energy: it is also a bubble. (author) 11 refs., 18 figs., 33 tabs.

  4. Launching Effectiveness Research to Guide Practice in Neurosurgery: A National Institute Neurological Disorders and Stroke Workshop Report.

    Science.gov (United States)

    Walicke, Patricia; Abosch, Aviva; Asher, Anthony; Barker, Fred G; Ghogawala, Zoher; Harbaugh, Robert; Jehi, Lara; Kestle, John; Koroshetz, Walter; Little, Roderick; Rubin, Donald; Valadka, Alex; Wisniewski, Stephen; Chiocca, E Antonio

    2017-04-01

    This workshop addressed challenges of clinical research in neurosurgery. Randomized controlled clinical trials (RCTs) have high internal validity, but often insufficiently generalize to real-world practice. Observational studies are inclusive but often lack sufficient rigor. The workshop considered possible solutions, such as (1) statistical methods for demonstrating causality using observational data; (2) characteristics required of a registry supporting effectiveness research; (3) trial designs combining advantages of observational studies and RCTs; and (4) equipoise, an identified challenge for RCTs. In the future, advances in information technology potentially could lead to creation of a massive database where clinical data from all neurosurgeons are integrated and analyzed, ending the separation of clinical research and practice and leading to a new "science of practice." Copyright © 2017 by the Congress of Neurological Surgeons.

  5. Training effectiveness when teaching the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) to medical students

    DEFF Research Database (Denmark)

    Liu, N; Zhou, M-W; Krassioukov, A V

    2013-01-01

    STUDY DESIGN: Interventional training sessions. OBJECTIVES: To examine the effectiveness of training medical students in the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). SETTING: A Peking University teaching hospital. METHODS: A total of 46 medical...... students were involved in the study. First, they had a 2-h self-study session with the ISNCSCI booklet, followed by a 10-item questionnaire. The booklet was allowed for use as a reference during this assessment. Two days later, the questionnaire was repeated without the use of reference. Students then had...... the second session with case presentations. The mean score of the final test increased significantly to 9.61 ± 0.88 (Pstudents in determining sensory level, motor level and American Spinal Injury Association Impairment Scale...

  6. The neurology of proverbs.

    Science.gov (United States)

    Van Lancker, D

    1990-01-01

    Although proverb tests are commonly used in the mental status examination surprisingly little is known about either normal comprehension or the interpretation of proverbial expressions. Current proverbs tests have conceptual and linguistic shortcomings, and few studies have been done to investigate the specific effects of neurological and psychiatric disorders on the interpretation of proverbs. Although frontal lobes have traditionally been impugned in patients who are "concrete", recent studies targeting deficient comprehension of non literal language (e.g. proverbs, idioms, speech formulas, and indirect requests) point to an important role of the right hemisphere (RH). Research describing responses of psychiatrically and neurologically classified groups to tests of proverb and idiom usage is needed to clarify details of aberrant processing of nonliteral meanings. Meanwhile, the proverb test, drawing on diverse cognitive skills, is a nonspecific but sensitive probe of mental status.

  7. The Neurology of Proverbs

    Directory of Open Access Journals (Sweden)

    Diana Van Lancker

    1990-01-01

    Full Text Available Although proverb tests are commonly used in the mental status examination surprisingly little is known about either normal comprehension or the interpretation of proverbial expressions. Current proverbs tests have conceptual and linguistic shortcomings, and few studies have been done to investigate the specific effects of neurological and psychiatric disorders on the interpretation of proverbs. Although frontal lobes have traditionally been impugned in patients who are “concrete”, recent studies targeting deficient comprehension of non literal language (e.g. proverbs, idioms, speech formulas, and indirect requests point to an important role of the right hemisphere (RH. Research describing responses of psychiatrically and neurologically classified groups to tests of proverb and idiom usage is needed to clarify details of aberrant processing of nonliteral meanings. Meanwhile, the proverb test, drawing on diverse cognitive skills, is a nonspecific but sensitive probe of mental status.

  8. Neurological legal disability

    Directory of Open Access Journals (Sweden)

    Radhakrishna H

    2006-01-01

    Full Text Available Neurological disorders with a prolonged course, either remediable or otherwise are being seen increasingly in clinical practice and many such patients are young and are part of some organization or other wherein their services are needed if they were healthy and fit. The neurologists who are on the panel of these organizations are asked to certify whether these subjects are fit to work or how long they should be given leave. These certificates may be produced in the court of law and may be subjected to verification by another neurologist or a medical board. At present there are no standard guidelines in our country to effect such certification unlike in orthopedic specialty or in ophthalmology. The following is a beginning, based on which the neurologist can certify the neurological disability of such subjects and convey the same meaning to all neurologists across the country.

  9. Determining mercury levels in anchovy and in individuals with different fish consumption habits, together with their neurological effects.

    Science.gov (United States)

    Çamur, Derya; Güler, Çağatay; Vaizoğlu, Songül Acar; Özdilek, Betül

    2016-07-01

    An increase in enviromental pollution may lead to mercury toxicity of fish origin due to the accumulative nature of methylmercury in fish. The main sources of human exposure to organic mercury compounds are contaminated fish and other seafoods. This descriptive study was planned to determine mercury levels in anchovy and in hair samples from individuals with different fish consumption habits, and to evaluate those individuals in terms of toxic effects. For that purpose, we analyzed 100 anchovies from the Black Sea and 100 anchovies from the Sea of Marmara, and assessed 25 wholesale workers in fish markets and 25 cleaning firm employees from both Ankara and Istanbul. Mercury levels in samples were measured using a cold vapor atomic absorption spectrophotometer. Participants were examined neurologically and mini mental state examination was applied to evaluate their cognitive functions. Mercury levels in fish were found to be below the national and international permitted levels. There was no statistically significant relation between mercury levels and the sea from which fish were caught. Hair mercury levels for all participants were within permitted ranges. However, hair mercury levels in both cities increased significantly with amount and frequency of fish consumption. A significant correlation was determined at correlation analysis between levels of fish consumption and hair mercury levels in the fishmongers and in the entire group (r = 0.32, p = 0.025; r = 0.23, p = 0.023, respectively). Neurological examination results were normal, except for a decrease in deep tendon reflexes in some participants in both cities. There was no correlation between Standardized Mini Mental State Examination results and hair mercury levels. We conclude that establishing a monitoring system for mercury levels in fish and humans will be useful in terms of evaluating potential neurotoxic effects. © The Author(s) 2014.

  10. Sports neurology topics in neurologic practice

    Science.gov (United States)

    Conidi, Francis X.; Drogan, Oksana; Giza, Christopher C.; Kutcher, Jeffery S.; Alessi, Anthony G.; Crutchfield, Kevin E.

    2014-01-01

    Summary We sought to assess neurologists' interest in sports neurology and learn about their experience in treating sports-related neurologic conditions. A survey was sent to a random sample of American Academy of Neurology members. A majority of members (77%) see at least some patients with sports-related neurologic issues. Concussion is the most common sports-related condition neurologists treat. More than half of survey participants (63%) did not receive any formal or informal training in sports neurology. At least two-thirds of respondents think it is very important to address the following issues: developing evidence-based return-to-play guidelines, identifying risk factors for long-term cognitive-behavioral sequelae, and developing objective diagnostic criteria for concussion. Our findings provide an up-to-date view of the subspecialty of sports neurology and identify areas for future research. PMID:24790800

  11. Neurologic complications of alcoholism.

    Science.gov (United States)

    Noble, James M; Weimer, Louis H

    2014-06-01

    This review serves as an overview of neurologic conditions associated with alcohol abuse or withdrawal, including epidemiology, clinical symptoms, diagnostic approach, and treatment. Frequent alcohol abuse and frank alcoholism are very common among adults in the United States. Although rates decline with each decade, as many as 10% of the elderly drink excessively. Given the ubiquitous nature of alcoholism in society, its complications have been clinically recognized for generations, with recent advances focusing on improved understanding of ethanol's biochemical targets and the pathophysiology of its complications. The chronic effects of alcohol abuse are myriad and include neurologic complications through both direct and indirect effects on the central and peripheral nervous systems. These disorders include several encephalopathic states related to alcohol intoxication, withdrawal, and related nutritional deficiencies; acute and chronic toxic and nutritional peripheral neuropathies; and myopathy. Although prevention of alcoholism and its neurologic complications is the optimal strategy, this article reviews the specific treatment algorithms for alcohol withdrawal and its related nutritional deficiency states.

  12. The effect of a micro bubble dispersed gas phase on hydrogen isotope transport in liquid metals under nuclear irradiation

    CERN Document Server

    Fradera, Jorge

    2013-01-01

    The present work intend to be a first step towards the understanding and quantification of the hydrogen isotope complex phenomena in liquid metals for nuclear technology. Liquid metals under nuclear irradiation in,e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles. Other liquid metal systems of a nuclear reactor involve hydrogen isotope absorption processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption into gas bubbles modelling and control may have a capital importance regarding design, operation and safety. Here general models for hydrogen isotopes transport in liquid metal and absorption into gas phase, that do not depend on the mass transfer limiting regime, are exposed and implemented in OpenFOAMR CFD tool for 0D to 3D simulations. Results for a 0D case show the impact of a He dispersed phase of na...

  13. Egalitarianism among Bubbles in Porous Media: An Ostwald Ripening Derived Anticoarsening Phenomenon

    Science.gov (United States)

    Xu, Ke; Bonnecaze, Roger; Balhoff, Matthew

    2017-12-01

    We show that smaller gas bubbles grow at the expense of larger bubbles and all bubbles approach the same surface curvature after long times in porous media. This anticoarsening effect is contrary to typical Ostwald ripening and leads to uniformly sized bubbles in a homogeneous medium. Evolution dynamics of bubble populations were measured, and mathematical models were developed that fit the experimental data well. Ostwald ripening is shown to be the driving mechanism in this anticoarsening phenomenon; however, the relationship between surface curvature and bubble size determined by the pore-throat geometric confinement reverses the ripening direction.

  14. Size distribution estimation of cavitation bubble cloud via bubbles dissolution using an ultrasound wide-beam method

    Science.gov (United States)

    Xu, Shanshan; Zong, Yujin; Liu, Xiaodong; Wan, Mingxi

    2017-03-01

    This paper proposed an acoustic technique to estimate size distribution of a cavitation bubble cloud induced by focused ultrasound (FUS) based on the dissolution of bubble cloud trapped by a wide beam of low acoustic pressure, after the acoustic exposure of FUS is turned off. Dissolution of cavitation bubbles in saline and in phase-shift nanodroplet emulsion diluted with degassed saline or saturated saline has been respectively studied to quantify the effects of pulse duration (PD) and acoustic power (AP) or peak negative pressure (PNP) of FUS on size distribution of cavitation bubbles.

  15. Intraalveolar bubbles and bubble films: III. Vulnerability and preservation in the laboratory.

    Science.gov (United States)

    Scarpelli, E M; Mautone, A J; Chinoy, M R; Defouw, D O; Clutario, B C

    1997-08-01

    Having confirmed (Scarpelli et al. 1996. Anat. Rec. 244:344-357 and 246:245-270) the discovery of intraalveolar bubbles and films as the normal anatomical infrastructure of aerated alveoli at all ages, we now address three questions. Why have these structures been so elusive? Visible in fresh lungs from the in vivo state, can they be preserved by known laboratory methods? Can they be preserved intact for study in tissue sections? Lungs of adult rabbits and pups were examined in thorax directly from the in vivo state to confirm normal bubbles both at functional residual capacity and at maximal volume; other lungs were permitted to deflate naturally to minimal volume. The fate of bubbles in situ (either intact, transected, or diced lung tissue) and of isolated bubbles was assessed (1) during conventional histopreparative processing, (2) during inflation-deflation after degassing, (3) after drying in air, (4) during and after quick freezing in liquid N2, and (5) after preservation in fixed and stained tissue sections prepared by a new double-impregnation procedure in which glutaraldehyde-fixed tissue was preembedded in agar, dehydrated and clarified chemically, embedded in paraffin, sectioned, and stained. Control studies included both blocking of bubble formation by rinsing the air spaces with Tween 20 prior to double impregnation and preparation of normal tissue without preembedding in agar. (1) Each of the following procedures in conventional processing dislocated and disrupted bubbles and films: osmium tetroxide and glutaraldehyde:formaldehyde:tannic acid mixture fixation; chemical dehydration (70-100% ethanol) and clarification (xylene and acetone); and embedding in paraffin or epoxy resin. Transection and dicing of the tissue aggravated the untoward effects. In contrast, bubbles and films remained stable in either glutaraldehyde or formaldehyde, which, however, did not protect against the other agents. (2) Degassing destroyed all bubbles as expected; however

  16. Effect of pure oxygen fine bubbles on the organic matter removal and bacterial community evolution treating coal gasification wastewater by membrane bioreactor.

    Science.gov (United States)

    Zhuang, Haifeng; Hong, Xiaoting; Han, Hongjun; Shan, Shengdao

    2016-12-01

    A lab-scale study was investigated to evaluate the effect of pure oxygen fine bubbles on membrane bioreactor (O2-MBR) performance of treating coal gasification wastewater. Compared with conventional MBR using aeration source of air (CMBR), the removal efficiencies of COD and total phenols increased by 28% and 36%, and the organic compositions of treated effluent represented significant difference that was mainly attributed to the controlled the foam expansion and enhanced the enzymatic activities in O2-MBR. Moreover, membrane fouling mitigation was observed in O2-MBR, probably owing to the less EPS amount and larger PSD. It was notable that the pure oxygen with fine bubbles promoted marked evolution of bacterial community from CMBR to O2-MBR, particularly, the bacterial community richness and diversity in O2-MBR was lower than CMBR, and the genera Phycisphaera, Comamonas, Thauera and Ohtaekwangia composed the top four most relative abundance genera in O2-MBR, giving the total relative abundance of 26.7%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Convective mass transfer around a dissolving bubble

    Science.gov (United States)

    Duplat, Jerome; Grandemange, Mathieu; Poulain, Cedric

    2017-11-01

    Heat or mass transfer around an evaporating drop or condensing vapor bubble is a complex issue due to the interplay between the substrate properties, diffusion- and convection-driven mass transfer, and Marangoni effects, to mention but a few. In order to disentangle these mechanisms, we focus here mainly on the convective mass transfer contribution in an isothermal mass transfer problem. For this, we study the case of a millimetric carbon dioxide bubble which is suspended under a substrate and dissolved into pure liquid water. The high solubility of CO2 in water makes the liquid denser and promotes a buoyant-driven flow at a high (solutal) Rayleigh number (Ra˜104 ). The alteration of p H allows the concentration field in the liquid to be imaged by laser fluorescence enabling us to measure both the global mass flux (bubble volume, contact angle) and local mass flux around the bubble along time. After a short period of mass diffusion, where the boundary layer thickens like the square root of time, convection starts and the CO2 is carried by a plume falling at constant velocity. The boundary layer thickness then reaches a plateau which depends on the bubble cross section. Meanwhile the plume velocity scales like (dV /d t )1 /2 with V being the volume of the bubble. As for the rate of volume loss, we recover a constant mass flux in the diffusion-driven regime followed by a decrease in the volume V like V2 /3 after convection has started. We present a model which agrees well with the bubble dynamics and discuss our results in the context of droplet evaporation, as well as high Rayleigh convection.

  18. Scaling laws and dynamics of bubble coalescence

    Science.gov (United States)

    Anthony, Christopher R.; Kamat, Pritish M.; Thete, Sumeet S.; Munro, James P.; Lister, John R.; Harris, Michael T.; Basaran, Osman A.

    2017-08-01

    The coalescence of bubbles and drops plays a central role in nature and industry. During coalescence, two bubbles or drops touch and merge into one as the neck connecting them grows from microscopic to macroscopic scales. The hydrodynamic singularity that arises when two bubbles or drops have just touched and the flows that ensue have been studied thoroughly when two drops coalesce in a dynamically passive outer fluid. In this paper, the coalescence of two identical and initially spherical bubbles, which are idealized as voids that are surrounded by an incompressible Newtonian liquid, is analyzed by numerical simulation. This problem has recently been studied (a) experimentally using high-speed imaging and (b) by asymptotic analysis in which the dynamics is analyzed by determining the growth of a hole in the thin liquid sheet separating the two bubbles. In the latter, advantage is taken of the fact that the flow in the thin sheet of nonconstant thickness is governed by a set of one-dimensional, radial extensional flow equations. While these studies agree on the power law scaling of the variation of the minimum neck radius with time, they disagree with respect to the numerical value of the prefactors in the scaling laws. In order to reconcile these differences and also provide insights into the dynamics that are difficult to probe by either of the aforementioned approaches, simulations are used to access both earlier times than has been possible in the experiments and also later times when asymptotic analysis is no longer applicable. Early times and extremely small length scales are attained in the new simulations through the use of a truncated domain approach. Furthermore, it is shown by direct numerical simulations in which the flow within the bubbles is also determined along with the flow exterior to them that idealizing the bubbles as passive voids has virtually no effect on the scaling laws relating minimum neck radius and time.

  19. Morphology of Rising Hydrodynamic and Magnetohydrodynamic Bubbles from Numerical Simulations

    Science.gov (United States)

    Robinson, K.; Dursi, L. J.; Ricker, P. M.; Rosner, R.; Calder, A. C.; Zingale, M.; Truran, J. W.; Linde, T.; Caceres, A.; Fryxell, B.; Olson, K.; Riley, K.; Siegel, A.; Vladimirova, N.

    2004-02-01

    Recent Chandra and XMM-Newton observations of galaxy cluster cooling flows have revealed X-ray emission voids of up to 30 kpc in size that have been identified with buoyant, magnetized bubbles. Motivated by these observations, we have investigated the behavior of rising bubbles in stratified atmospheres using the FLASH9 adaptive-mesh simulation code. We present results from two-dimensional simulations with and without the effects of magnetic fields and with varying bubble sizes and background stratifications. We find purely hydrodynamic bubbles to be unstable; a dynamically important magnetic field is required to maintain a bubble's integrity. This suggests that, even absent thermal conduction, for bubbles to be persistent enough to be regularly observed, they must be supported in large part by magnetic fields. Thermal conduction unmitigated by magnetic fields can dissipate the bubbles even faster. We also observe that the bubbles leave a tail as they rise; the structure of these tails can indicate the history of the dynamics of the rising bubble.

  20. Frictional Drag Reduction by Bubbles in Taylor-Couette Flow

    Science.gov (United States)

    Murai, Yuichi; Oiwa, Hiroshi; Takeda, Yasushi

    2006-11-01

    Frictional drag reduction provided with small bubbles is investigated experimentally using a Couette-Taylor flow system, i.e. shear flow between concentric cylinders. Torque and bubble behavior are measured up to Re=4500 when air bubbles are injected constantly and rise through the cells. Silicone oil is used for avoiding uncertain interfacial property of bubbles as well as for keeping nearly mono-sized bubbles. We assess the effect of drag reduction with two types of evaluation factors, i.e. sensitivity and power gain. The sensitivity exceeds unity at Redrag is reduced more than the drop of mixture density. This originates from accumulation of bubbles into the rotating inner cylinder, which is little affected by turbulence. The power gain, which is defined by drag reduction power per bubble injection power, takes the highest value of O(10) at higher Re numbers around 2500. The image processing measurement finds this reason to be disappearance of azimuthal waves when the organized bubbles distribution transits from toroidal to spiral modes. Moreover, the axial spacing of bubble clouds expands during the transition, enforcing the reduction of momentum exchange.

  1. Microscopic bubble behaviour in suppression pool during wetwell venting

    Science.gov (United States)

    Zablackaite, G.; Nagasaka, H.; Kikura, H.

    2017-10-01

    During a severe accident PCV failure should be avoided and fission products inside PCV should be confined as much as possible. In order to minimize FPs release, Wetwell venting is conducted by releasing steam-non-condensable gas mixture carrying FPs from the Drywell to Suppression Pool. Steam is condensed by subcooled water in the pool, and most of FPs are retained into water. The removal of FP in the water pool is referred to as “Pool Scrubbing effect”. Hydrodynamic parameters of bubbles have impact on pool scrubbing effect. However, there is only few data available to evaluate quantitatively the bubble behaviour under depressurization and/or thermal stratification conditions. Series of experiments were conducted to evaluate the influence of temperature distribution, non-condensable gas content and pressure in the Wetwell on bubble behaviour. Bubbles were visualized using High Speed Camera and adopting shadowgraphy technique. Applying Particle Tracking Velocimetry, bubble velocity and size distribution were obtained from recorded images. Experimental results show that with increasing suppression pool temperature, bubbles reaching the pool surface decreased in size and traveling velocity became slower. In pressurized wetwell, bubble behaviour was similar to that in the heated up suppression pool case, although bubble parameters were similar to the low temperature case. Higher air content induced water surface movement and bubbles were smaller due to break up.

  2. Effects of estrogen on functional and neurological recovery after spinal cord injury: An experimental study with rats

    Directory of Open Access Journals (Sweden)

    Olavo Biraghi Letaif

    2015-10-01

    Full Text Available OBJECTIVES:To evaluate the functional and histological effects of estrogen as a neuroprotective agent after a standard experimentally induced spinal cord lesion.METHODS:In this experimental study, 20 male Wistar rats were divided into two groups: one group with rats undergoing spinal cord injury (SCI at T10 and receiving estrogen therapy with 17-beta estradiol (4mg/kg immediately following the injury and after the placement of skin sutures and a control group with rats only subjected to SCI. A moderate standard experimentally induced SCI was produced using a computerized device that dropped a weight on the rat's spine from a height of 12.5 mm. Functional recovery was verified with the Basso, Beattie and Bresnahan scale on the 2nd, 7th, 14th, 21st, 28th, 35th and 42nd days after injury and by quantifying the motor-evoked potential on the 42nd day after injury. Histopathological evaluation of the SCI area was performed after euthanasia on the 42nd day.RESULTS:The experimental group showed a significantly greater functional improvement from the 28th to the 42nd day of observation compared to the control group. The experimental group showed statistically significant improvements in the motor-evoked potential compared with the control group. The results of pathological histomorphometry evaluations showed a better neurological recovery in the experimental group, with respect to the proportion and diameter of the quantified nerve fibers.CONCLUSIONS:Estrogen administration provided benefits in neurological and functional motor recovery in rats with SCI beginning at the 28th day after injury.

  3. Bubble growth in a narrow horizontal space

    Energy Technology Data Exchange (ETDEWEB)

    Stutz, Benoit; Goulet, Remi [CETHIL, UMR5008, CNRS, INSA-Lyon, Universite Lyon1 (France); Passos, Julio Cesar [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. LABSOLAR

    2009-07-01

    The purpose of this work is to develop an axis-symmetric two-phase flow model describing the growth of a single bubble squeezed between a horizontal heated upward-facing disc and an insulating surface placed parallel to the heated surface. Heat transfers at the liquid-vapour interfaces are predicted by the kinetic limit of vaporisation. The depths of the liquid films deposed on the surfaces (heated surface and confinement space) are determined using the Moriyama and Inoue correlation (1996). Transient heat transfers within the heated wall are taken into account. The model is applied to pentane bubble growth. The influence of the gap size, the initial temperature of the system, the thermal effusivity of the heated wall and the kinetic limit of vaporisation are studied. The results show that the expansion of the bubbles strongly depends on the gap size and can be affected by the effusivity of the material. Mechanical inertia effects are mainly dominant at the beginning of the bubble expansion. Pressure drop induced by viscous effects have to be taken into account for high capillary numbers. Heat transfers at the meniscus are negligible except at the early stages of the bubble growth. (author)

  4. The Liberal Arts Bubble

    Science.gov (United States)

    Agresto, John

    2011-01-01

    The author expresses his doubt that the general higher education bubble will burst anytime soon. Although tuition, student housing, and book costs have all increased substantially, he believes it is still likely that the federal government will continue to pour billions into higher education, largely because Americans have been persuaded that it…

  5. BEBC bubble chamber

    CERN Multimedia

    CERN PhotoLab

    1972-01-01

    Looking up into the interior of BEBC bubble chamber from the expansion cylinder. At the top of the chamber two fish-eye lenses are installed and three other fish-eye ports are blanked off. In the centre is a heat exchanger.

  6. Scanning bubble chamber pictures

    CERN Multimedia

    1974-01-01

    These were taken at the 2 m hydrogen bubble chamber. The photo shows an early Shiva system where the pre-measurements needed to qualify the event were done manually (cf photo 7408136X). The scanning tables were located in bld. 12. Gilberte Saulmier sits on foreground, Inge Arents at centre.

  7. Heavy liquid bubble chamber

    CERN Multimedia

    CERN PhotoLab

    1965-01-01

    The CERN Heavy liquid bubble chamber being installed in the north experimental hall at the PS. On the left, the 1180 litre body; in the centre the magnet, which can produce a field of 26 800 gauss; on the right the expansion mechanism.

  8. The Effects of Chiropractic Treatment on Students With Learning and Behavioral Impairments Due to Neurological Dysfunction.

    Science.gov (United States)

    Walton, E. V.; Brzozowski, Walter T.

    The effects of chiropractic treatment on children with learning and behavioral problems was investigated with 24 elementary and secondary level students, 12 receiving regular chiropractic treatment and 12 receiving medication. Results indicated that chiropractic treatment was more effective for the wide range symptoms common in the neurological…

  9. Neurological effects of white spirit: Contribution of animal studies during a 30-year period

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Damgård; Lund, Søren Peter; Ladefoged, Ole

    2006-01-01

    , but the neurophysiological tests showed adverse effects at this level. Fourth, neurophysiological methods may be more sensitive than histopathological, neurobehavioural and neurochemical methods. Overall, white spirit with a high and a low content of aromatics showed no overt difference in long-term effects in animals......Numerous studies have suggested that long-term occupational exposure to white spirit may cause chronic toxic encephalopathy (WHO 1996). This review summarizes the chronic nervous system effects of white spirit in animal studies during a 30-year period. First, routine histopathology was consistently...... unable to reveal adverse peripheral or central nervous system effects after inhalation of white spirit. Second, neurobehavioural studies in animals showed no adverse effect after inhalation of white spirit with a high content of aromatics in contrast to what was found with products with a low content...

  10. Effects of 600 MeV proton irradiation on nucleation and growth of precipitates and helium bubbles in a high-purity Al-Mg-Si alloy

    DEFF Research Database (Denmark)

    Singh, Bachu Narain; Leffers, Torben; Victoria, M.

    1986-01-01

    bubbles were seen in the grain interior as well as at the grain boundaries. Long rows of bubbles were observed with the same orientation in the matrix as the precipitate needles. Grain boundary bubbles were found to grow faster in the Al-Mg-Si alloy than in the high-purity aluminium...... to have dissolved during the later stages of irradiation. Thermally aged reference specimens have also been investigated. The needle-shaped precipitates in the aged and the irradiated specimens lie along the 〈100〉 matrix directions. At 150°C bubbles were observed only at grain boundaries whereas at 240°C...

  11. Characteristics of bubble plumes, bubble-plume bubbles and waves from wind-steepened wave breaking

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G. de

    2007-01-01

    Observations of breaking waves, associated bubble plumes and bubble-plume size distributions were used to explore the coupled evolution of wave-breaking, wave properties and bubble-plume characteristics. Experiments were made in a large, freshwater, wind-wave channel with mechanical wind-steepened

  12. Bubbling controlled by needle movement

    Energy Technology Data Exchange (ETDEWEB)

    Vejrazka, Jiri; Fujasova, Maria; Stanovsky, Petr; Ruzicka, Marek C; Drahos, JirI [Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojova 135, 165 02 Prague (Czech Republic)], E-mail: vejrazka@icpf.cas.cz

    2008-07-30

    A device for 'on-demand' production of bubbles is presented. The device is based on a movable needle, through which air is injected. Bubbling is controlled by a rapid needle movement, which induces the bubble detachment. Conditions for proper function of the device include the restriction on the flow rate through the needle, sufficient needle pressure drop and adequate needle acceleration. Functionality of the device is demonstrated. Bubbling from a stationary needle is also discussed and a scaling for bubble size is proposed for the case of short needles, to which a constant flow rate is imposed through tubes of a finite volume.

  13. Neurology and neurologic practice in China.

    Science.gov (United States)

    Shi, Fu-Dong; Jia, Jian-Ping

    2011-11-29

    In the wake of dramatic economic success during the past 2 decades, the specialized field of neurology has undergone a significant transformation in China. With an increase in life expectancy, the problems of aging and cognition have grown. Lifestyle alterations have been associated with an epidemiologic transition both in the incidence and etiology of stroke. These changes, together with an array of social issues and institution of health care reform, are creating challenges for practicing neurologists throughout China. Notable problems include overcrowded, decrepit facilities, overloaded physician schedules, deteriorating physician-patient relationships, and an insufficient infrastructure to accommodate patients who need specialized neurologic care. Conversely, with the creation of large and sophisticated neurology centers in many cities across the country, tremendous opportunities exist. Developments in neurologic subspecialties enable delivery of high-quality care. Clinical and translational research based on large patient populations as well as highly sophisticated technologies are emerging in many neurologic centers and pharmaceutical companies. Child neurology and neurorehabilitation will be fast-developing subdisciplines. Given China's extensive population, the growth and progress of its neurology complex, and its ever-improving quality control, it is reasonable to anticipate that Chinese neurologists will contribute notably to unraveling the pathogenic factors causing neurologic diseases and to providing new therapeutic solutions.

  14. Monte Carlo simulation of spectral reflectance and BRDF of the bubble layer in the upper ocean.

    Science.gov (United States)

    Ma, Lanxin; Wang, Fuqiang; Wang, Chengan; Wang, Chengchao; Tan, Jianyu

    2015-09-21

    The presence of bubbles can significantly change the radiative properties of seawater and these changes will affect remote sensing and underwater target detection. In this work, the spectral reflectance and bidirectional reflectance characteristics of the bubble layer in the upper ocean are investigated using the Monte Carlo method. The Hall-Novarini (HN) bubble population model, which considers the effect of wind speed and depth on the bubble size distribution, is used. The scattering coefficients and the scattering phase functions of bubbles in seawater are calculated using Mie theory, and the inherent optical properties of seawater for wavelengths between 300 nm and 800 nm are related to chlorophyll concentration (Chl). The effects of bubble coating, Chl, and bubble number density on the spectral reflectance of the bubble layer are studied. The bidirectional reflectance distribution function (BRDF) of the bubble layer for both normal and oblique incidence is also investigated. The results show that bubble populations in clear waters under high wind speed conditions significantly influence the reflection characteristics of the bubble layer. Furthermore, the contribution of bubble populations to the reflection characteristics is mainly due to the strong backscattering of bubbles that are coated with an organic film.

  15. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  16. The therapeutic effect of neurologic music therapy and speech language therapy in post-stroke aphasic patients.

    Science.gov (United States)

    Lim, Kil-Byung; Kim, Yong-Kyun; Lee, Hong-Jae; Yoo, Jeehyun; Hwang, Ji Youn; Kim, Jeong-Ah; Kim, Sung-Kyun

    2013-08-01

    To investigate the therapeutic effect of neurologic music therapy (NMT) and speech language therapy (SLT) through improvement of the aphasia quotient (AQ) in post-stroke aphasic patients. Twenty-one post-stroke, nonfluent aphasia patients who had ischemic/hemorrhagic stroke on radiologic evaluation were divided into the NMT and SLT groups. They received NMT and SLT for 1 month. Language function was assessed by Korean version-Western Aphasia Battery before and after therapy. NMT consisted of therapeutic singing and melodic intonation therapy, and SLT consisted of language-oriented therapy. Significant improvements were revealed in AQ, repetition, and naming after therapy in the NMT group and improvements in repetition in the SLT group of chronic stroke patients (p<0.05). There were significant improvements in language ability in the NMT group of subacute stroke patients. However, there was no significant improvement in the SLT group of subacute stroke patients. We concluded that the two therapies are effective treatments in the chronic stage of stroke and NMT is effective in subacute post-stroke aphasic patients.

  17. Ring Bubbles of Dolphins

    Science.gov (United States)

    Shariff, Karim; Marten, Ken; Psarakos, Suchi; White, Don J.; Merriam, Marshal (Technical Monitor)

    1996-01-01

    The article discusses how dolphins create and play with three types of air-filled vortices. The underlying physics is discussed. Photographs and sketches illustrating the dolphin's actions and physics are presented. The dolphins engage in this behavior on their own initiative without food reward. These behaviors are done repeatedly and with singleminded effort. The first type is the ejection of bubbles which, after some practice on the part of the dolphin, turn into toroidal vortex ring bubbles by the mechanism of baroclinic torque. These bubbles grow in radius and become thinner as they rise vertically to the surface. One dolphin would blow two in succession and guide them to fuse into one. Physicists call this a vortex reconnection. In the second type, the dolphins first create an invisible vortex ring in the water by swimming on their side and waving their tail fin (also called flukes) vigorously. This vortex ring travels horizontally in the water. The dolphin then turns around, finds the vortex and injects a stream of air into it from its blowhole. The air "fills-out" the core of the vortex ring. Often, the dolphin would knock-off a smaller ring bubble from the larger ring (this also involves vortex reconnection) and steer the smaller ring around the tank. One other dolphin employed a few other techniques for planting air into the fluke vortex. One technique included standing vertically in the water with tail-up, head-down and tail piercing the free surface. As the fluke is waved to create the vortex ring, air is entrained from above the surface. Another technique was gulping air in the mouth, diving down, releasing air bubbles from the mouth and curling them into a ring when they rose to the level of the fluke. In the third type, demonstrated by only one dolphin, the longitudinal vortex created by the dorsal fin on the back is used to produce 10-15 foot long helical bubbles. In one technique she swims in a curved path. This creates a dorsal fin vortex since

  18. In Situ Measurement of Local Hydrogen Production Rate by Bubble-Evolved Recording

    Directory of Open Access Journals (Sweden)

    Xiaowei Hu

    2013-01-01

    Full Text Available Hydrogen visibly bubbles during photocatalytic water splitting under illumination with above-bandgap radiation, which provides a direct measurement of local gas-evolving reaction rate. In this paper, optical microscopy of superfield depth was used for recording the hydrogen bubble growth on Cd0.5Zn0.5S photocatalyst in reaction liquid and illuminated with purple light. By analyzing change of hydrogen bubble size as a function of time, we understood that hydrogen bubble growth experienced two periods, which were inertia effect dominated period and diffusion effect dominated period, respectively. The tendency of hydrogen bubble growth was similar to that of the gas bubble in boiling, while the difference in bubble diameter and growth time magnitude was great. Meanwhile, we obtained the local hydrogen production rate on photocatalyst active site by measuring hydrogen bubble growth variation characteristics. This method makes it possible to confirm local actual hydrogen evolution rate quantitatively during photocatalytic water splitting.

  19. Effectiveness of Chin-tuck Maneuver to Facilitate Swallowing in Neurologic Dysphagia

    Directory of Open Access Journals (Sweden)

    Saconato, Mariana

    2015-10-01

    Full Text Available Introduction The chin-tuck maneuver is the most frequently employed postural maneuver in the treatment of neurogenic oropharyngeal dysphagia caused by encephalic vascular strokes and degenerative diseases. Objective The purpose of this study was to investigate the effectiveness of this maneuver in patients with neurogenic dysphagia and factors that could interfere in it. Methods In this retrospective cohort, we analyzed the medical files and videofluoroscopy exams of 35 patients (19 male – 54% and 16 female – 46%; age range between 20 and 89 years old; mean = 69 years. Results The results suggest that the effectiveness of chin-tuck maneuver is related to the overall degree of dysphagia: the more severe the dysphagia, the less effective the maneuver. Conclusion Chin-tuck maneuver should benefit dysphagic patients with delay in the swallowing trigger, reduced laryngeal elevation, and difficulties to swallow liquids, but is not the best compensatory strategy for patients with severe dysphagia.

  20. On the accuracy of the void fraction measurements using optical probes in bubbly flows

    Science.gov (United States)

    Enrique Juliá, J.; Harteveld, Wouter K.; Mudde, Robert F.; Van den Akker, Harrie E. A.

    2005-03-01

    The accuracy of the measurement of the void fraction in bubbly flows using an optical probe is investigated. Experiments were performed in tap water with ellipsoidal-shaped air bubbles with equivalent diameters and velocities in the range of 2.8-5.2 mm and 0.22-0.28 m/s. Comparison of charge coupled devices (CCD) images of dynamic bubble piercing events with optical probe signals shows that for piercing in the area around the bubble side, the so-called low-level criterion gives the best agreement with the actual gas-liquid transition for the undisturbed bubble. In addition, residence time underestimation due to a partial blinding effect is observed in the outer regions of the bubble. Residence times of the probe inside the bubble are obtained from the probe signal and from CCD images of the undisturbed bubble. These are compared to study the relevance of various probe-bubble interaction effects. The crawling effect is found to play an important role. For perpendicular piercing, the experiment shows that in the central area of the bubble deceleration effects induced by the probe lead to local overestimation of residence times. In the outer region of the bubble, large-scale deformation leads to local underestimation of residence times. The larger cross-sectional area associated with the underestimation leads to a net underestimation of the total bubble volume. For nonperpendicular piercing, the probe inclination is found to generate an additional drifting effect, creating an additional source of underestimation.

  1. Neurological complications of underwater diving.

    Science.gov (United States)

    Rosińska, Justyna; Łukasik, Maria; Kozubski, Wojciech

    2015-01-01

    The diver's nervous system is extremely sensitive to high ambient pressure, which is the sum of atmospheric and hydrostatic pressure. Neurological complications associated with diving are a difficult diagnostic and therapeutic challenge. They occur in both commercial and recreational diving and are connected with increasing interest in the sport of diving. Hence it is very important to know the possible complications associated with this kind of sport. Complications of the nervous system may result from decompression sickness, pulmonary barotrauma associated with cerebral arterial air embolism (AGE), otic and sinus barotrauma, high pressure neurological syndrome (HPNS) and undesirable effect of gases used for breathing. The purpose of this review is to discuss the range of neurological symptoms that can occur during diving accidents and also the role of patent foramen ovale (PFO) and internal carotid artery (ICA) dissection in pathogenesis of stroke in divers. Copyright © 2014 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  2. Risks from accidental exposures to engineered nanoparticles and neurological health effects: A critical review

    Directory of Open Access Journals (Sweden)

    Mattsson Mats-Olof

    2010-12-01

    Full Text Available Abstract There are certain concerns regarding the safety for the environment and human health from the use of engineered nanoparticles (ENPs which leads to unintended exposures, as opposed to the use of ENPs for medical purposes. This review focuses on the unintended human exposure of ENPs. In particular, possible effects in the brain are discussed and an attempt to assess risks is performed. Animal experiments have shown that investigated ENPs (metallic nanoparticles, quantum dots, carbon nanotubes can translocate to the brain from different entry points (skin, blood, respiratory pathways. After inhalation or instillation into parts of the respiratory tract a very small fraction of the inhaled or instilled ENPs reaches the blood and subsequently secondary organs, including the CNS, at a low translocation rate. Experimental in vivo and in vitro studies have shown that several types of ENPs can have various biological effects in the nervous system. Some of these effects could also imply that ENPs can cause hazards, both acutely and in the long term. The relevance of these data for risk assessment is far from clear. There are at present very few data on exposure of the general public to either acute high dose exposure or on chronic exposure to low levels of air-borne ENPs. It is furthermore unlikely that acute high dose exposures would occur. The risk from such exposures for damaging CNS effects is thus probably very low, irrespective of any biological hazard associated with ENPs. The situation is more complicated regarding chronic exposures, at low doses. The long term accumulation of ENPs can not be excluded. However, we do not have exposure data for the general public regarding ENPs. Although translocation to the brain via respiratory organs and the circulation appears to be very low, there remains a possibility that chronic exposures, and/or biopersistent ENPs, can influence processes within the brain that are triggering or aggravating

  3. A polydisperse two-fluid model for surf zone bubble simulation

    Science.gov (United States)

    Ma, Gangfeng; Shi, Fengyan; Kirby, James T.

    2011-05-01

    Wave breaking in the surf zone entrains large volumes of air bubbles into the water column, forming a two-phase bubbly flow field. Numerical study of bubbly flow is largely restricted by the lack of robust and comprehensive bubble entrainment models. In this paper, we propose a new model that connects bubble entrainment with turbulent dissipation rate at the air-water interface. The entrainment model as well as a polydisperse two-fluid model are incorporated into a 3-D volume of fluid code TRUCHAS. The bubbly flow model is first tested against laboratory experimental data for an oscillatory bubble plume. The calculated time-averaged liquid velocities and their fluctuations agree well with measurements, indicating that the model correctly reproduces dynamic interactions between the liquid phase and the continuum representation of the gas phase. Then, it is employed to study the bubbly flow under a laboratory surf zone breaking wave. Through the comparisons with experimental data, it is demonstrated that the model describes bubble entrainment and void fraction evolution reasonably well. The exponential decay of void fraction observed in the laboratory experiments is captured by the model. The kinematics of bubble plume as well as the vertical evolution of bubble size spectrum at any depth are investigated. Studies of bubble effects on liquid phase turbulence show that the presence of bubbles could suppress a large amount of turbulence under breaking waves.

  4. The neurological effects of ghrelin in brain diseases: Beyond metabolic functions.

    Science.gov (United States)

    Jiao, Qian; Du, Xixun; Li, Yong; Gong, Bing; Shi, Limin; Tang, Tingting; Jiang, Hong

    2017-02-01

    Ghrelin, a peptide released by the stomach that plays a major role in regulating energy metabolism, has recently been shown to have effects on neurobiological behaviors. Ghrelin enhances neuronal survival by reducing apoptosis, alleviating inflammation and oxidative stress, and accordingly improving mitochondrial function. Ghrelin also stimulates the proliferation, differentiation and migration of neural stem/progenitor cells (NS/PCs). Additionally, the ghrelin is benefit for the recovery of memory, mood and cognitive dysfunction after stroke or traumatic brain injury. Because of its neuroprotective and neurogenic roles, ghrelin may be used as a therapeutic agent in the brain to combat neurodegenerative disease. In this review, we highlight the pre-clinical evidence and the proposed mechanisms underlying the role of ghrelin in physiological and pathological brain function. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Impact of money supply on stock bubbles

    Directory of Open Access Journals (Sweden)

    Martin Širůček

    2013-01-01

    Full Text Available This article focuses on the effect and implications of changes in money supply in the US on stock bubble rise on the US capital market, which is represented by the Dow Jones Industrial Average index. This market was chosen according to the market capitalization. The attention of the paper is drawn to issues – if according to the results of empirical analysis, the money supply is a significant factor which causes the bubbles and if during the time the significance and impact of this macroeconomic factor on stock index increase.

  6. Nonlinear dynamic behavior of microscopic bubbles near a rigid wall

    Science.gov (United States)

    Suslov, Sergey A.; Ooi, Andrew; Manasseh, Richard

    2012-06-01

    The nonlinear dynamic behavior of microscopic bubbles near a rigid wall is investigated. Oscillations are driven by the ultrasonic pressure field that arises in various biomedical applications such as ultrasound imaging or targeted drug delivery. It is known that, when bubbles approach a blood-vessel wall, their linear dynamic response is modified. This modification may be very useful for real-time detection of bubbles that have found targets; in future therapeutic technologies, it may be useful for controlled release of medical agents encapsulating microbubbles. In this paper, the nonlinear response of microbubbles near a wall is studied. The Keller-Miksis-Parlitz equation is adopted, but modified to account for the presence of a rigid wall. This base model describes the time evolution of the bubble surface, which is assumed to remain spherical, and accounts for the effect of acoustic radiation losses owing to liquid compressibility in the momentum conservation. Two situations are considered: the base case of an isolated bubble in an unbounded medium, and a bubble near a rigid wall. In the latter case, the wall influence is modeled by including a symmetrically oscillating image bubble. The bubble dynamics is traced using a numerical solution of the model equation. Subsequently, Floquet theory is used to accurately detect the bifurcation point where bubble oscillations stop following the driving ultrasound frequency and undergo period-changing bifurcations. Of particular interest is the detection of the subcritical period-tripling and -quadrupling transition. The parametric bifurcation maps are obtained as functions of nondimensional parameters representing the bubble radius, the frequency and pressure amplitude of the driving ultrasound field, and the distance from the wall. It is shown that the presence of the wall generally stabilises the bubble dynamics, so that much larger values of the pressure amplitude are needed to generate nonlinear responses. Thus, a

  7. The effect of pre-nutrition of hydroalcoholic extractof Origanum vulgare on brain edema and neurologic deficits in a rat stroke model

    Directory of Open Access Journals (Sweden)

    Meysam Foroozandeh

    2015-10-01

    Full Text Available Background and Aim: Stroke is one of the most important factors of mortality and disability in the world. Free radicals are produced following ischemic stroke and they play a central role in breaking the blood-brain barrier and  causing brain edema formation. The aim of the current study was to evaluate the effect of hydro- alcoholic extract of Origanum vulgare on brain edema and neurologic deficit in a rat stroke model. Materials and Methods: In thisexperimental study, 35 male Wistar rats were randomly divided into 5 equal groups.  The first  two groups (control and Sham received distilled water, while three treatment groups received oral Origanum vulgare extract for 30days (50,75and 100 mg/kgdaily, respectively.  Two hours after the last dose of Origanum vulgare extract,each main group underwent  a 60 min middle cerebral artery occlusion.  Then, the assessment of blood brain edema, and neurologic deficits analysis were done . Brain edema (brain water content was analyzed by One-Way ANOVA using LSD method and neurologic deficits analysis by means of Mann-Whitney U, and P<0.05 was taken as the significant level. Results: Origanum vulgare extract reduced brain edema in the experimental groups of 50 (82.49±0.47, 75 (80.89±0.63 and 100 mg/kg/day (80.80±0.66 compared to the control group (84.46±0.67. The neurologic deficit scores in the experimental groups of 75and 100mg/kg/day, compared with control group, but neurologic deficit scores did not affect the group receiving the dose 50 mg/kg. Conclusion:  The obtained data indicate that Origanum vulgar extract via reduction of brain edema and neurologic deficits scorescan have a protective effect on the stroke model.

  8. The Role of Confinement in Bubble Collapse in a Channel

    Science.gov (United States)

    Rodriguez, Mauro; Alahyari Beig, Shahaboddin; Johnsen, Eric; Barbier, Charlotte

    2017-11-01

    In a variety of applications, cavitation bubbles collapse near solid objects give rise to damage in certain extreme cases. Numerous detailed computational studies have been conducted of a single bubble collapsing near a rigid wall. However, there are known situations where the bubbles collapse in a confined configuration, such as in biomedical applications and in the spallation neutron source. However, the effect of confinement (e.g., in the case of bubble collapse in a narrow channel) is poorly understood. In the present work, we quantify the effect of confinement on the bubble dynamics, pressures and temperatures produced from a single bubble collapsing in a channel. An in-house, solution-adaptive, high-order accurate shock- and interface-capturing method is used to solve the 3D compressible Navier-Stokes equations for gas/liquid flows. We demonstrate the conditions under which the channel walls strengthen/weaken the violence of the collapse and result in amplifying/reducing the wall pressures and temperatures. We further determine the smallest channel width, relative to the initial bubble radius, for which the presence of a second wall affects the collapse. Additional simulations of multiple bubbles collapsing in a channel are underway and will be discussed. This research was supported in part by ONR Grant N00014-12-1-0751 and NSF Grant CBET 1253157.

  9. Translocation and potential neurological effects of fine and ultrafine particles a critical update

    Directory of Open Access Journals (Sweden)

    Geiser Marianne

    2006-09-01

    Full Text Available Abstract Particulate air pollution has been associated with respiratory and cardiovascular disease. Evidence for cardiovascular and neurodegenerative effects of ambient particles was reviewed as part of a workshop. The purpose of this critical update is to summarize the evidence presented for the mechanisms involved in the translocation of particles from the lung to other organs and to highlight the potential of particles to cause neurodegenerative effects. Fine and ultrafine particles, after deposition on the surfactant film at the air-liquid interface, are displaced by surface forces exerted on them by surfactant film and may then interact with primary target cells upon this displacement. Ultrafine and fine particles can then penetrate through the different tissue compartments of the lungs and eventually reach the capillaries and circulating cells or constituents, e.g. erythrocytes. These particles are then translocated by the circulation to other organs including the liver, the spleen, the kidneys, the heart and the brain, where they may be deposited. It remains to be shown by which mechanisms ultrafine particles penetrate through pulmonary tissue and enter capillaries. In addition to translocation of ultrafine particles through the tissue, fine and coarse particles may be phagocytized by macrophages and dendritic cells which may carry the particles to lymph nodes in the lung or to those closely associated with the lungs. There is the potential for neurodegenerative consequence of particle entry to the brain. Histological evidence of neurodegeneration has been reported in both canine and human brains exposed to high ambient PM levels, suggesting the potential for neurotoxic consequences of PM-CNS entry. PM mediated damage may be caused by the oxidative stress pathway. Thus, oxidative stress due to nutrition, age, genetics among others may increase the susceptibility for neurodegenerative diseases. The relationship between PM exposure and CNS

  10. Lithium Toxicity and Neurologic Effects: Probable Neuroleptic Malignant Syndrome Resulting from Lithium Toxicity

    Directory of Open Access Journals (Sweden)

    Osamede Edokpolo

    2012-01-01

    Full Text Available Introduction. We present the case of a patient who developed lithium toxicity with normal therapeutic levels, as a result of pharmacokinetic interaction with Valsartan, and probable Neuroleptic Malignant Syndrome from the ensuing lithium toxicity. Case Presentation. A 59-year old black male with bipolar disorder maintained on lithium and fluphenazine therapy presented with a 2 week history of worsening confusion, tremor, and gait abnormality. He recently had his dose of Valsartan increased. At presentation, patient had signs of autonomic instability, he was confused, dehydrated, and had rigidity of upper extremities. Significant labs on admission were lithium level-1.2, elevated CK-6008, leukocytosis WBC-22, and renal impairment; Creatinine-4.1, BUN-35, HCO3-20.1, and blood glucose 145. CT/MRI brain showed old cerebral infarcts, and there was no evidence of an infective process. Lithium and fluphenazine were discontinued, his lithium levels gradually decreased, and he improved with supportive treatment including rehydration and correction of electrolyte imbalance. Conclusions. This case illustrates that lithium toxicity can occur within therapeutic levels, and the neurotoxic effect of lithium can include Neuroleptic Malignant Syndrome. Clinicians should be aware of the risk associated with drug interactions with lithium.

  11. Effect of ischemic pretreatment on heat shock protein 72, neurologic outcome, and histopathologic outcome in a rabbit model of spinal cord ischemia

    NARCIS (Netherlands)

    de Haan, P.; Vanicky, I.; Jacobs, M. J.; Bakker, O.; Lips, J.; Meylaerts, S. A.; Kalkman, C. J.

    2000-01-01

    In the present study, we investigated the effect of ischemic pretreatment on heat shock protein 72 concentration and neurologic and histopathologic outcome after transient spinal cord ischemia. In 28 New Zealand White rabbits, an aortic occlusion device was placed infrarenally. The animals were

  12. Quantum Subcritical Bubbles

    Science.gov (United States)

    Uesugi, T.; Morikawa, M.; Shiromizu, T.

    1996-08-01

    We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using a quantum statistical average. Furthermore, based on our study, we discuss implications for the dynamics of phase transitions.

  13. Popping the filter bubble

    OpenAIRE

    Hughes, Katie; Cronin, G; Welch, L

    2017-01-01

    So-called “fake news” is everywhere and is having a major impact on daily life from politics to education. The rapid growth of information and the numbers of people who can create it means that we need more sophisticated tools to process the news we receive. Join us to learn about different methods you can use to be your own fact checker and pop your filter bubble.

  14. BubbleDeck

    OpenAIRE

    ECT Team, Purdue

    2013-01-01

    Conventional horizontal concrete slabs are heavy that limit their spans. Enhancement of span results in addition of beams that increases the cost of the structure. Thus, there is a need for a technology that will help in increasing the span by reducing weight of the span. BubbleDeck is a revolutionary construction method that virtually eliminates concrete from the middle of a floor slab between columns that does not perform any structural function, thereby dramatically reducing structural dea...

  15. Research on 3D reconstruction measurement and parameter of cavitation bubble based on stereo vision

    Science.gov (United States)

    Li, Shengyong; Ai, Xiaochuan; Wu, Ronghua; Cao, Jing

    2017-02-01

    The problems caused by the cavitation bubble and caused many adverse effects on the ship propeller, hydraulic machinery and equipment. In order to research the production mechanism of cavitation bubble under different conditions, cavitation bubble zone parameter fine measurement and analysis technology is indispensable, this paper adopts a non-contact measurement method of optical autonomous construction of binocular stereo vision measurement system according to the characteristics of cavitation bubble, the texture features are not clear, transparent and difficult to obtain, 3D imaging measurement of cavitation bubble using composite dynamic lighting, and 3D reconstruction of cavitation bubble region and obtained the characteristics of more accurate parameters, test results show that the cavitation bubble characteristics of the fine technology can obtain and analyze cavitation bubble region and instability.

  16. Effective dose estimation for oncological and neurological PET/CT procedures.

    Science.gov (United States)

    Martí-Climent, Josep M; Prieto, Elena; Morán, Verónica; Sancho, Lidia; Rodríguez-Fraile, Macarena; Arbizu, Javier; García-Velloso, María J; Richter, José A

    2017-12-01

    The aim of this study was to retrospectively evaluate the patient effective dose (ED) for different PET/CT procedures performed with a variety of PET radiopharmaceutical compounds. PET/CT studies of 210 patients were reviewed including Torso (n = 123), Whole body (WB) (n = 36), Head and Neck Tumor (HNT) (n = 10), and Brain (n = 41) protocols with (18)FDG (n = 170), (11)C-CHOL (n = 10), (18)FDOPA (n = 10), (11)C-MET (n = 10), and (18)F-florbetapir (n = 10). ED was calculated using conversion factors applied to the radiotracer activity and to the CT dose-length product. Total ED (mean ± SD) for Torso-(11)C-CHOL, Torso-(18)FDG, WB-(18)FDG, and HNT-(18)FDG protocols were 13.5 ± 2.2, 16.5 ± 4.5, 20.0 ± 5.6, and 15.4 ± 2.8 mSv, respectively, where CT represented 77, 62, 69, and 63% of the protocol ED, respectively. For (18)FDG, (18)FDOPA, (11)C-MET, and (18)F-florbetapir brain PET/CT studies, ED values (mean ± SD) were 6.4 ± 0.6, 4.6 ± 0.4, 5.2 ± 0.5, and 9.1 ± 0.4 mSv, respectively, and the corresponding CT contributions were 11, 14, 23, and 26%, respectively. In (18)FDG PET/CT, variations in scan length and arm position produced significant differences in CT ED (p PET/CT protocols with different radiopharmaceuticals ranged between 4.6 and 20.0 mSv. The major contributor to total ED for body protocols is CT, whereas for brain studies, it is the PET radiopharmaceutical.

  17. CFD Simulations of an Air-Water Bubble Column: Effect of Luo Coalescence Parameter and Breakup Kernels.

    Science.gov (United States)

    Syed, Alizeb Hussain; Boulet, Micael; Melchiori, Tommaso; Lavoie, Jean-Michel

    2017-01-01

    In this work, CFD simulations of an air-water bubbling column were performed and validated with experimental data. The superficial gas velocities used for the experiments were 0.019 and 0.038 m/s and were considered as an homogeneous regime. The former involves simpler physics when compared to a heterogeneous regime where the superficial velocities are higher. In order to simulate the system, a population balance model (PBM) was solved numerically using a discrete method and a closure kernels involving the Luo coalescence model as well as two different breakup models: Luo's and Lehr's. For the multi-phase calculations, an eulerian framework was selected and the interphase momentum transfer included drag, lift, wall lubrication, and turbulent dispersion terms. A sensitivity analysis was performed on a Luo coalescence kernel by changing the coalescence parameter (c0) from 1.1 to 0.1 and results showed that the radial profiles of gas holdup and axial liquid velocity were significantly affected by such parameter. From the simulation results, the main conclusions were: (a) A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo) combined with a decreasing value of c0 improves the gas holdup profiles as compared to empirical values. However, at the lowest value of c0 investigated in this work, the axial liquid velocity deteriorates with regards to experimental data when using a superficial gas velocity of 0.019 m/s. (b) A combination of the Luo coalescence and Lehr breakup models (Luo-Lehr) was shown to improve the gas holdup values with experimental data when compared to the Luo-Luo kernels. However, as c0 decreases, the Luo-Lehr models underestimate the axial liquid velocity profiles with regards to empirical values. (c) A first and second order numerical schemes allowed predicting similar radial profiles of gas holdup and axial liquid velocity. (d) The mesh sensitivity results show that a 3 mm mesh size can be considered as reasonable for simulating

  18. CFD Simulation of an Air-Water Bubble Column: Effect of Luo coalescence parameter and breakup kernels

    Science.gov (United States)

    Syed, Alizeb Hussain; Boulet, Micael; Melchiori, Tommaso; Lavoie, Jean-Michel

    2017-09-01

    In this work, CFD simulations of an air-water bubbling column were performed and validated with experimental data. The superficial gas velocities used for the experiments were 0.019 m/s and 0.038m/s and were considered as an homogeneous regime. The former involves simpler physics when compared to a heterogeneous regime where the superficial velocities are higher. In order to simulate the system, a population balance model (PBM) was solved numerically using a discrete method and a closure kernels involving the Luo coalescence model as well as two different breakup models: Luo's and Lehr's. For the multi-phase calculations, an eulerian framework was selected and the interphase momentum transfer included drag, lift, wall lubrication, and turbulent dispersion terms. A sensitivity analysis was performed on a Luo coalescence kernel by changing the coalescence parameter (c0) from 1.1 to 0.1 and results showed that the radial profiles of gas holdup and axial liquid velocity were significantly affected by such parameter. From the simulation results, the main conclusions were: (a) A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo) combined with a decreasing value of c0 improves the gas holdup profiles as compared to empirical values. However, at the lowest value of c0 investigated in this work, the axial liquid velocity deteriorates with regards to experimental data when using a superficial gas velocity of 0.019 m/s. (b) A combination of the Luo coalescence and Lehr breakup models (Luo-Lehr) was shown to improve the gas holdup values with experimental data when compared to the Luo-Luo kernels. However, as c0 decreases, the Luo-Lehr models underestimate the axial liquid velocity profiles with regards to empirical values. (c) A first and second order numerical schemes allowed predicting similar radial profiles of gas holdup and axial liquid velocity. (d) The mesh sensitivity results show that a 3 mm mesh size can be considered as reasonable for simulating

  19. CFD Simulations of an Air-Water Bubble Column: Effect of Luo Coalescence Parameter and Breakup Kernels

    Directory of Open Access Journals (Sweden)

    Alizeb Hussain Syed

    2017-09-01

    Full Text Available In this work, CFD simulations of an air-water bubbling column were performed and validated with experimental data. The superficial gas velocities used for the experiments were 0.019 and 0.038 m/s and were considered as an homogeneous regime. The former involves simpler physics when compared to a heterogeneous regime where the superficial velocities are higher. In order to simulate the system, a population balance model (PBM was solved numerically using a discrete method and a closure kernels involving the Luo coalescence model as well as two different breakup models: Luo's and Lehr's. For the multi-phase calculations, an eulerian framework was selected and the interphase momentum transfer included drag, lift, wall lubrication, and turbulent dispersion terms. A sensitivity analysis was performed on a Luo coalescence kernel by changing the coalescence parameter (c0 from 1.1 to 0.1 and results showed that the radial profiles of gas holdup and axial liquid velocity were significantly affected by such parameter. From the simulation results, the main conclusions were: (a A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo combined with a decreasing value of c0 improves the gas holdup profiles as compared to empirical values. However, at the lowest value of c0 investigated in this work, the axial liquid velocity deteriorates with regards to experimental data when using a superficial gas velocity of 0.019 m/s. (b A combination of the Luo coalescence and Lehr breakup models (Luo-Lehr was shown to improve the gas holdup values with experimental data when compared to the Luo-Luo kernels. However, as c0 decreases, the Luo-Lehr models underestimate the axial liquid velocity profiles with regards to empirical values. (c A first and second order numerical schemes allowed predicting similar radial profiles of gas holdup and axial liquid velocity. (d The mesh sensitivity results show that a 3 mm mesh size can be considered as reasonable for

  20. Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

    Science.gov (United States)

    Leifer, Ira; Chernykh, Denis; Shakhova, Natalia; Semiletov, Igor

    2017-06-01

    Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s-1 to derive the in situ calibration curve (Q(σ)). These nonlinear curves related flux (Q) to sonar return (σ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering - precluding the use of a theoretical approach to derive Q(σ) from the product of the bubble σ(r) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ(σ)) with respect to Q found Ψ(σ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ(σ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ(σ) was bimodal for all but the weakest plumes. Q(σ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes (Qm) were 5.56, 42.73, and 4.88 mmol s-1 for MBES data with good to reasonable agreement (4-37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ(Q)) was bimodal, with weak Ψ(Q) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.

  1. Influence of drag closures and inlet conditions on bubble dynamics and flow behavior inside a bubble column

    Directory of Open Access Journals (Sweden)

    Amjad Asad

    2017-01-01

    Full Text Available In this paper, the hydrodynamics of a bubble column is investigated numerically using the discrete bubble model, which tracks the dispersed bubbles individually in a liquid column. The discrete bubble model is combined with the volume of fluid approach to account for a proper free surface boundary condition at the liquid–gas interface. This improves describing the backflow region, which takes place close to the wall region. The numerical simulation is conducted by means of the open source computational fluid dynamics library OpenFOAM®. In order to validate the numerical model, experimental results of a bubble column are used. The numerical prediction shows an overall good agreement compared to the experimental data. The effect of injection conditions and the influence of the drag closures on bubble dynamics are investigated in the current paper. Here, the significant effect of injection boundary conditions on bubble dynamics and flow velocity in the studied cavity is revealed. Moreover, the impact of the choice of the drag closure on the liquid velocity field and on bubble behavior is indicated by comparing three drag closures derived from former studies.

  2. Effectiveness of online and face-to-face fatigue self-management programmes for adults with neurological conditions.

    Science.gov (United States)

    Ghahari, Setareh; Packer, Tanya

    2012-01-01

    To evaluate effectiveness of a face-to-face and an online fatigue self-management programme and to compare these to two control groups (information-only and no-intervention) in a sample of adults (n = 115) with neurological conditions reporting extreme fatigue. Non-equivalent pre-test post-test control group design using the Fatigue Impact Scale, Personal Wellbeing Index and Activity Card Sort as primary outcome measures. Participants in the two intervention groups and the information-only group showed clinically significant improvements in fatigue over time (p < 0.05). When compared to the no-intervention group, face-to-face participants showed significantly greater improvement in overall and cognitive fatigue, while participants in the online group showed significant improvement in self-efficacy and stress. Participation in either the online or face-to-face programme appears to result in improved self-management, however, with different potency depending on outcomes. The improvement in the online information only group further complicates the understanding of the results. With few other comparisons of online and face-to-face self-management protocols available, further research is needed to understand differential impacts which may be related to the delivery format, the rural versus urban split of participants or other unknown factors.

  3. Post-marketing observational program of the effectiveness of fluvoxamine for the treatment of depression in patients with neurological disorders: the FRIENDS study

    Directory of Open Access Journals (Sweden)

    Yahno NN

    2017-11-01

    Full Text Available Nikolay N Yahno,1 Anastasia V Fedotova2 1Neurology Department, I.M. Sechenov First Moscow State Medical University, 2Neurology Department, Additional Professional Education Faculty, Pirogov Russian National Research Medical University, Moscow, Russian Federation Abstract: In a prospective, non-blinded, uncontrolled, multicenter, post-marketing, observational study (FRIENDS; NCT02043197, fluvoxamine (50–300 mg/day for 90 days was effective for the treatment of depression in 299 adult patients (age ≥18 years with neurological disorders at baseline. The therapeutic effect of fluvoxamine was measured by means of changes in the Hospital Anxiety and Depression Scale depression and anxiety scores (HADS-D and HADS-A, respectively, global severity of illness, and clinical condition (measured using the Clinical Global Improvement [CGI] scale. The mean HADS-D subscale score at baseline in the per-protocol cohort (n=296 was 11.7±3.1 points and the corresponding mean HADS-A score was 12.6±3.2. Significant (P<0.0001 improvements in both scores were recorded during fluvoxamine treatment and later follow-up. Most patients (>85% recorded reductions versus baseline in both indices. In the CGI-based assessment, most evaluated patients (>200 experienced moderate to very substantial clinical improvement, with no or limited side effects. Significant improvements were also recorded in the exploratory outcomes of sleep quality, assessed using the Insomnia Severity Index, and cognitive function, assessed using the Montreal Cognitive Assessment (P<0.0001 vs baseline for both. No death or serious adverse drug reactions were reported during the study. The results of this observational study affirm that fluvoxamine is effective and well tolerated for the treatment of depression in the context of neurological disorders. The effects on the exploratory endpoints of this research merit evaluation in controlled trials. Keywords: depression, anxiety, fluvoxamine

  4. Acoustic power dependences of sonoluminescence and bubble dynamics.

    Science.gov (United States)

    Lee, Hyang-Bok; Choi, Pak-Kon

    2014-11-01

    The decreasing effect of sonoluminescence (SL) in water at high acoustic powers was investigated in relation to bubble dynamics and acoustic emission spectra. The intensity of SL was measured in the power range of 1-18W at 83.8kHz for open-end (free liquid surface and film-covered surface) and fixed-end boundaries of sound fields. The power dependence of the SL intensity showed a maximum and then decrease to zero for all the boundaries. Similar results were obtained for sonochemiluminescence in luminol solution. The power dependence of the SL intensity was strongly correlated with the bubble dynamics captured by high-speed photography at 64kfps. In the low-power range where the SL intensity increases, bubble streamers were observed and the population of streaming bubbles increased with the power. At powers after SL maximum occurred, bubble clusters came into existence. Upon complete SL reduction, only bubble clusters were observed. The subharmonic in the acoustic emission spectra increased markedly in the region where bubble clusters were observed. Nonspherical oscillations of clustering bubbles may make a major contribution to the subharmonic. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Bubble behavior characteristics based on virtual binocular stereo vision

    Science.gov (United States)

    Xue, Ting; Xu, Ling-shuang; Zhang, Shang-zhen

    2018-01-01

    The three-dimensional (3D) behavior characteristics of bubble rising in gas-liquid two-phase flow are of great importance to study bubbly flow mechanism and guide engineering practice. Based on the dual-perspective imaging of virtual binocular stereo vision, the 3D behavior characteristics of bubbles in gas-liquid two-phase flow are studied in detail, which effectively increases the projection information of bubbles to acquire more accurate behavior features. In this paper, the variations of bubble equivalent diameter, volume, velocity and trajectory in the rising process are estimated, and the factors affecting bubble behavior characteristics are analyzed. It is shown that the method is real-time and valid, the equivalent diameter of the rising bubble in the stagnant water is periodically changed, and the crests and troughs in the equivalent diameter curve appear alternately. The bubble behavior characteristics as well as the spiral amplitude are affected by the orifice diameter and the gas volume flow.

  6. Behavior of gas seep bubbles below the hydrate stability zone

    Science.gov (United States)

    Wang, B.; Jun, I.; Hutschenreuter, K.; Socolofsky, S. A.; Kessler, J. D.; Lavery, A.; Breier, J. A., Jr.; Seewald, J.

    2016-02-01

    Two research cruises (GISR G07 and G08) have been carried out during 2014-2015 to study the behavior of natural gas seep plumes escaping on the seafloor below the hydrate stability zone at MC 118 and GC 600 in the Gulf of Mexico. Quantitative image measurements suggest both temporal and spatial variation of the bubble size and gas flow rate. Hydrate formation on the natural gas seep bubbles was a very fast process in the deep sea environment (890 and 1200 m depth), where the measured methane concentration in water close to the source was also saturated. The measured rise velocities of the bubbles differed significantly from the predicted terminal velocities using empirical equations in Clift et al. (1978). The measured bubble characteristics (size distribution and flow rate) were provided as input to a bubble dissolution model, which accounts for the effect of hydrate on the mass transfer coefficient. The model shows results consistent with the measurements.

  7. Cavitation inception from bubble nuclei

    Science.gov (United States)

    Mørch, K. A.

    2015-01-01

    The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure–time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes. PMID:26442138

  8. [Neurorehabilitation, neurology, rehabilitation medicine].

    Science.gov (United States)

    Urbán, Edina; Szél, István; Fáy, Veronika; Dénes, Zoltán; Lippai, Zoltán; Fazekas, Gábor

    2013-05-30

    We have read several publications of great authority on the neurological profession in the last two years in which were expressed assessments of the current situation combined with opinions about neurology and the necessity to reorganize neurological patient care. These articles took up the question of neurorehabilitation too. The authors, who on a daily basis, deal with the rehabilitation of people with disabilities as a consequence of neurological conditions, summarize some important definitions of rehabilitation medicine and the present system of neurological rehabilitation, as it is defined by the rehabilitation profession.

  9. Neurology at the bedside

    DEFF Research Database (Denmark)

    Kondziella, Daniel; Waldemar, Gunhild

    This updated and expanded new edition takes neurology trainees by the hand and guides them through the whole patient encounter - from an efficient neurological history and bedside examination through to differential diagnosis, diagnostic procedures and treatment. At each step the expert authors......, as have new chapters including neurogenetics, neurorehabilitation, neurocritical care and heuristic neurological reasoning. In addition, this second edition now includes more than 100 unique case histories. Neurology at the Bedside, Second Edition is written for neurologists in all stages of training....... Medical students, general practitioners and others with an interest in neurology will also find invaluable information here....

  10. In Search of the Big Bubble

    Science.gov (United States)

    Simoson, Andrew; Wentzky, Bethany

    2011-01-01

    Freely rising air bubbles in water sometimes assume the shape of a spherical cap, a shape also known as the "big bubble". Is it possible to find some objective function involving a combination of a bubble's attributes for which the big bubble is the optimal shape? Following the basic idea of the definite integral, we define a bubble's surface as…

  11. Neurology and literature 2.

    Science.gov (United States)

    Iniesta, I

    2014-05-01

    Good literary fiction has the potential to move us, extend our sense of life, transform our prospective views and help us in the face of adversity. A neurological disorder is likely to be the most challenging experience a human being may have to confront in a lifetime. As such, literary recreations of illnesses have a doubly powerful effect. Study the synergies between neurology and fictional literature with particular reference to narrative based medicine (NBM). Doctors establish boundaries between the normal and the abnormal. Taking a clinical history is an act of interpretation in which the doctor integrates the science of objective signs and measurable quantities with the art of subjective clinical judgment. The more discrepancy there is between the patient's experience with the illness and the doctor's interpretation of that disease, the less likely the doctor-patient interaction is to succeed. NBM contributes to a better discernment of the meanings, thus considering disease as a biographical event rather than just a natural fact. Drawing from their own experience with disease, writers of fiction provide universal insights through their narratives, whilst neuroscientists, like Cajal, have occasionally devoted their scientific knowledge to literary narratives. Furthermore, neurologists from Alzheimer to Oliver Sacks remind us of the essential value of NBM in the clinic. Integrating NBM (the narrative of patients) and the classic holistic approach to patients with our current paradigm of evidence based medicine represents a challenge as relevant to neurologists as keeping up with technological and scientific advances. Copyright © 2011 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  12. CFD Modeling of Gas-Liquid Bubbly Flow in Horizontal Pipes: Influence of Bubble Coalescence and Breakup

    Directory of Open Access Journals (Sweden)

    K. Ekambara

    2012-01-01

    Full Text Available Modelling of gas-liquid bubbly flows is achieved by coupling a population balance equation with the three-dimensional, two-fluid, hydrodynamic model. For gas-liquid bubbly flows, an average bubble number density transport equation has been incorporated in the CFD code CFX 5.7 to describe the temporal and spatial evolution of the gas bubbles population. The coalescence and breakage effects of the gas bubbles are modeled. The coalescence by the random collision driven by turbulence and wake entrainment is considered, while for bubble breakage, the impact of turbulent eddies is considered. Local spatial variations of the gas volume fraction, interfacial area concentration, Sauter mean bubble diameter, and liquid velocity are compared against experimental data in a horizontal pipe, covering a range of gas (0.25 to 1.34 m/s and liquid (3.74 to 5.1 m/s superficial velocities and average volume fractions (4% to 21%. The predicted local variations are in good agreement with the experimental measurements reported in the literature. Furthermore, the development of the flow pattern was examined at three different axial locations of L/D = 25, 148, and 253. The first location is close to the entrance region where the flow is still developing, while the second and the third represent nearly fully developed bubbly flow patterns.

  13. Neurological complications of chickenpox

    Directory of Open Access Journals (Sweden)

    Girija A

    2007-01-01

    Full Text Available Aim: To assess the neurological complications of chickenpox with prognosis. Background: The neurological complications occur in 0.03% of persons who get chickenpox. There is no universal vaccination against chicken pox in India. Most patients prefer alternate modalities of treatment. Hence these complications of chickenpox are likely to continue to occur. Study Design: A prospective study was conducted for 2 years (from March 2002 on the admitted cases with neurological complications after chickenpox (with rash or scar. Patients were investigated with CT/MRI, CSF study, EEG and nerve conduction studies and hematological workup. They were followed-up for 1 year and outcome assessed using modified Rankin scale. Results: The latency for the neurological complications was 4-32 days (mean: 16.32 days. There were 18 cases: 10 adults (64% and 8 children (36%. Cerebellar ataxia (normal CT/MRI was observed in 7 cases (32% (mean age: 6.85 years. One patient (6 years had acute right hemiparesis in the fifth week due to left capsular infarct. All these cases spontaneously recovered by 4 weeks. The age range of the adult patients was 13-47 years (mean: 27 years. The manifestations included cerebellar and pyramidal signs (n-4 with features of demyelination in MRI who recovered spontaneously or with methylprednisolone by 8 weeks. Patient with encephalitis recovered in 2 weeks with acyclovir. Guillain Barre syndrome of the demyelinating type (n-2 was treated with Intravenous immunoglobulin (IVIG and they had a slow recovery by a modified Rankin scale (mRs score of 3 and 2 at 6 months and 1 year, respectively. One case died after hemorrhage into the occipital infarct. There were two cases of asymmetrical neuropathy, one each of the seventh cranial and brachial neuritis. Conclusion: Spontaneous recovery occurs in post-chickenpox cerebellar ataxia. Rarely, serious complications can occur in adults. The demyelinating disorders, either of the central or peripheral

  14. Bubble measuring instrument and method

    Science.gov (United States)

    Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)

    2003-01-01

    Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

  15. Electroweak bubble wall speed limit

    Science.gov (United States)

    Bödeker, Dietrich; Moore, Guy D.

    2017-05-01

    In extensions of the Standard Model with extra scalars, the electroweak phase transition can be very strong, and the bubble walls can be highly relativistic. We revisit our previous argument that electroweak bubble walls can "run away," that is, achieve extreme ultrarelativistic velocities γ ~ 1014. We show that, when particles cross the bubble wall, they can emit transition radiation. Wall-frame soft processes, though suppressed by a power of the coupling α, have a significance enhanced by the γ-factor of the wall, limiting wall velocities to γ ~ 1/α. Though the bubble walls can move at almost the speed of light, they carry an infinitesimal share of the plasma's energy.

  16. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats

    DEFF Research Database (Denmark)

    Hyldegaard, Ole; Kerem, Dikla; Melamed, Y

    2011-01-01

    . We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture...... breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent...

  17. Neurological aspects of grief.

    Science.gov (United States)

    Silva, Adriana C; de Oliveira Ribeiro, Natalia P; de Mello Schier, Alexandre R; Arias-Carrión, Oscar; Paes, Flavia; Nardi, Antonio E; Machado, Sergio; Pessoa, Tamires M

    2014-01-01

    Despite grief being a universal experience and the increased scientific attention paid to grief and bereavement in recent years, studies that seek to better understand the role of the neurological aspects of grief are still scarce. We found 5 studies that discussed the relationship between the neurological aspects of grief due to the death of a loved one. All studies showed an activation of common areas, i.e., the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), prefrontal cortex (PFC), insula and amygdala. These findings could indicate that there is a group of areas working together and responding to generate the symptomatology of grief. Because grief is a universal experience, it is essential that the necessary and effective support can be provided to those who experience the loss of someone considered important in their lives, and this requires understanding grief's manifestation, its differential diagnosis in reference to other clinical conditions, mainly psychiatric ones, and adequate forms of intervention and treatment when necessary. Proper understanding and support can help prevent the emergence of more serious health problems.

  18. Combined experimental and theoretical investigation of the gas bubble motion in an acoustic field.

    Science.gov (United States)

    Ma, Xiaojian; Xing, Tianyu; Huang, Biao; Li, Qiuhe; Yang, Yifei

    2018-01-01

    The objective of this paper is to apply the combined experimental and theoretical method to investigate the various behaviors of gas bubbles in an acoustic field. In the experiments, high-speed video and ultrasonic processor are used to capture the transient evolution of gas bubble patterns, as well as velocity profiles. In the theoretical analysis, the theories of primary and secondary Bjerknes forces and buoyancy force are introduced to accurately demonstrate the variations of bubble volume and motion. Results are presented for gas bubbles with the radius of 1.4mm under an acoustic field with a frequency of 18kHz, for three cases, namely single bubble rising in a quiescent liquid, acoustic single bubble oscillation and two bubbles coalescence conditions. The results show that the fragments around the single gas bubble presents the periodical behaviors, namely, splitting, attraction, and secondary splitting motion. The centroid of the single gas bubble almost oscillates without motion upwards or downwards, because of the equilibrium of the primary Bjerknes force caused by acoustic waves and the effect of the buoyancy force. For the two coalescing bubbles, the resultant of buoyancy, primary and secondary Bjerknes forces acting on two bubbles are same in magnitude, but in opposite direction, which indicates that two gas bubbles attract each other and and coalesce into one. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Heat transport in bubbling turbulent convection.

    Science.gov (United States)

    Lakkaraju, Rajaram; Stevens, Richard J A M; Oresta, Paolo; Verzicco, Roberto; Lohse, Detlef; Prosperetti, Andrea

    2013-06-04

    Boiling is an extremely effective way to promote heat transfer from a hot surface to a liquid due to numerous mechanisms, many of which are not understood in quantitative detail. An important component of the overall process is that the buoyancy of the bubble compounds with that of the liquid to give rise to a much-enhanced natural convection. In this article, we focus specifically on this enhancement and present a numerical study of the resulting two-phase Rayleigh-Bénard convection process in a cylindrical cell with a diameter equal to its height. We make no attempt to model other aspects of the boiling process such as bubble nucleation and detachment. The cell base and top are held at temperatures above and below the boiling point of the liquid, respectively. By keeping this difference constant, we study the effect of the liquid superheat in a Rayleigh number range that, in the absence of boiling, would be between 2 × 10(6) and 5 × 10(9). We find a considerable enhancement of the heat transfer and study its dependence on the number of bubbles, the degree of superheat of the hot cell bottom, and the Rayleigh number. The increased buoyancy provided by the bubbles leads to more energetic hot plumes detaching from the cell bottom, and the strength of the circulation in the cell is significantly increased. Our results are in general agreement with recent experiments on boiling Rayleigh-Bénard convection.

  20. Chapter 38: American neurology.

    Science.gov (United States)

    Freemon, Frank R

    2010-01-01

    The great formative event in the history of North America, the Civil War of 1861 to 1865, was the stimulus for the development of clinical neurology and the neurosciences. The first neurological research center on the continent was the US Army hospital at Turner's Lane, Philadelphia, PA. Silas Weir Mitchell and his colleagues described causalgia (reflex sympathetic dystrophy), phantom limb sensation, and Horner's syndrome (before Horner). The medical leader of the Northern army was William Hammond. After the conclusion of hostilities, he began a huge clinical practice in New York City. In the United States, clinical neurology began in private practice, unlike Europe, where neurology began in institutions. Hammond's textbook, which first used the term athetosis, was used by a generation of physicians who encountered patients with neurological signs and symptoms. Early in the 20th century, neurological institutions were formed around universities; probably the most famous was the Montreal Neurological Institute founded by Wilder Penfield. The US federal government sponsored extensive research into the function and dysfunction of the nervous system through the Neurological Institute of Neurological Diseases and Blindness, later called the National Institute of Neurological Diseases and Stroke. The government officially classified the final 10 years of the 20th century as the Decade of the Brain and provided an even greater level of research funding.

  1. DAMPAK DEFISIENSI IODIUM MATERNAL PADA PERSISTENSI DISFUNGSI NEUROPSIKOLOGIS ANAK USIA 12 TAHUN (EFFECT OF MATERNAL IODINE DEFICIENCY ON THE PERSISTENCE OF NEUROLOGICAL DYSFUNCTIONS IN CHILDREN AGED 12 YEARS

    Directory of Open Access Journals (Sweden)

    Basuki Budiman

    2012-06-01

    Full Text Available ABSTRACT Study on the last effect of neuropsychologic dysfunction due to iodine deficiency during gestation is still scarce. This study is to confirm the persistence of neuropsychological dysfunctions at 12-year-old of children born from pregnant mothers with iodine deficiency in endemic iodine deficient area. The study is 13-year-cohort design. Iodine status (Total T4, TSH and UIE of pregnant mothers at initial study, neonatal (TSH and 12 year-old iodine status (fT4, TSH are performed. Neurological dysfunction of infants is examined every 6 weeks until the child age is 24 months. Neuropsychological dysfunction of children 12 years of age such as minimal brain dysfunction and psychological battery of Wechsler Intelligence Scale for Children (WISC are also administered. A screening to determine case and reference using is done using mini mental status examination (MMSE. Score MMSE of 28 or less are implemented as cases while others as reference. The relationship of neurological and cognitive dysfunction with both maternal iodine status and neurological dysfunction at 2 months of neonates age are elaborated. The persistency risk of neurological dysfunction at 12 years of age is 8% (95%ci: 1-15%. Maternal and neonatal iodine status (as indicated by TSH, T4 are the risk factors for the persistency at 12-years. However, delays of neurological development in two-month old infants are found as directly risk factors. Median Total IQ score for all participants are far lower than the lowest limit of normal range. A very significant difference (p=0.000 are found in Total IQ score between cases and references. Discrepancy analysis of IQV-IQP indicates brain lesions in subtle form, such as diadokhokinesis, praxis, memory, distractibility and lowered IQ score. Neuropsychological dysfunctions due maternal iodine deficiency are still persistence at 12 years. Maternal T4 during gestation is not only influences on the persistency but also impaires directly on the

  2. Pharmacological intervention against bubble-induced platelet aggregation in a rat model of decompression sickness.

    Science.gov (United States)

    Pontier, Jean-Michel; Vallée, Nicolas; Ignatescu, Mihaela; Bourdon, Lionel

    2011-03-01

    Decompression sickness (DCS) with alterations in coagulation system and formation of platelet thrombi occurs when a subject is subjected to a reduction in environmental pressure. Blood platelet consumption after decompression is clearly linked to bubble formation in humans and offers an index for evaluating DCS severity in animal models. Previous studies highlighted a predominant involvement of platelet activation and thrombin generation in bubble-induced platelet aggregation (BIPA). To study the mechanism of the BIPA in DCS, we examined the effect of acetylsalicylic acid (ASA), heparin (Hep), and clopidogrel (Clo), with anti-thrombotic dose pretreatment in a rat model of DCS. Male Sprague-Dawley rats (n = 208) were randomly assigned to one experimental group treated before the hyperbaric exposure and decompression protocol either with ASA (3×100 mg·kg(-1)·day(-1), n = 30), Clo (50 mg·kg(-1)·day(-1), n = 60), Hep (500 IU/kg, n = 30), or to untreated group (n = 49). Rats were first compressed to 1,000 kPa (90 msw) for 45 min and then decompressed to surface in 38 min. In a control experiment, rats were treated with ASA (n = 13), Clo (n = 13), or Hep (n = 13) and maintained at atmospheric pressure for an equivalent period of time. Onset of DCS symptoms and death were recorded during a 60-min observation period after surfacing. DCS evaluation included pulmonary and neurological signs. Blood samples for platelet count (PC) were taken 30 min before hyperbaric exposure and 30 min after surfacing. Clo reduces the DCS mortality risk (mortality rate: 3/60 with Clo, 15/30 with ASA, 21/30 with Hep, and 35/49 in the untreated group) and DCS severity (neurological DCS incidence: 9/60 with Clo, 6/30 with ASA, 5/30 with Hep, and 12/49 in the untreated group). Clo reduced fall in platelet count and BIPA (-4,5% with Clo, -19.5% with ASA, -19,9% with Hep, and -29,6% in the untreated group). ASA, which inhibits the thromboxane A2 pathway, and Hep, which inhibits thrombin

  3. Bubble reconstruction method for wire-mesh sensors measurements

    Science.gov (United States)

    Mukin, Roman V.

    2016-08-01

    A new algorithm is presented for post-processing of void fraction measurements with wire-mesh sensors, particularly for identifying and reconstructing bubble surfaces in a two-phase flow. This method is a combination of the bubble recognition algorithm presented in Prasser (Nuclear Eng Des 237(15):1608, 2007) and Poisson surface reconstruction algorithm developed in Kazhdan et al. (Poisson surface reconstruction. In: Proceedings of the fourth eurographics symposium on geometry processing 7, 2006). To verify the proposed technique, a comparison was done of the reconstructed individual bubble shapes with those obtained numerically in Sato and Ničeno (Int J Numer Methods Fluids 70(4):441, 2012). Using the difference between reconstructed and referenced bubble shapes, the accuracy of the proposed algorithm was estimated. At the next step, the algorithm was applied to void fraction measurements performed in Ylönen (High-resolution flow structure measurements in a rod bundle (Diss., Eidgenössische Technische Hochschule ETH Zürich, Nr. 20961, 2013) by means of wire-mesh sensors in a rod bundle geometry. The reconstructed bubble shape yields bubble surface area and volume, hence its Sauter diameter d_{32} as well. Sauter diameter is proved to be more suitable for bubbles size characterization compared to volumetric diameter d_{30}, proved capable to capture the bi-disperse bubble size distribution in the flow. The effect of a spacer grid was studied as well: For the given spacer grid and considered flow rates, bubble size frequency distribution is obtained almost at the same position for all cases, approximately at d_{32} = 3.5 mm. This finding can be related to the specific geometry of the spacer grid or the air injection device applied in the experiments, or even to more fundamental properties of the bubble breakup and coagulation processes. In addition, an application of the new algorithm for reconstruction of a large air-water interface in a tube bundle is

  4. Effect of Admission Glasgow Coma Scale Motor Score on Neurological Outcome in Out-of-Hospital Cardiac Arrest Patients Receiving Therapeutic Hypothermia.

    Science.gov (United States)

    Hifumi, Toru; Kuroda, Yasuhiro; Kawakita, Kenya; Sawano, Hirotaka; Tahara, Yoshio; Hase, Mamoru; Nishioka, Kenji; Shirai, Shinichi; Hazui, Hiroshi; Arimoto, Hideki; Kashiwase, Kazunori; Kasaoka, Shunji; Motomura, Tomokazu; Yasuga, Yuji; Yonemoto, Naohiro; Yokoyama, Hiroyuki; Nagao, Ken; Nonogi, Hiroshi

    2015-01-01

    Because the initial (on admission) Glasgow Coma Scale (GCS) examination has not been fully evaluated in comatose survivors of cardiac arrest (CA) who receive therapeutic hypothermia (TH), the aim of the present study was to determine any association between the admission GCS motor score and neurologic outcomes in patients with out-of-hospital CA who receive TH. In the J-PULSE-HYPO study registry, patients with bystander-witnessed CA were eligible for inclusion. Patients were divided into 3 groups based on GCS motor score (1, 2-3, and 4-5) to assess various effects on neurologic outcome. Univariate and multivariate analyses were performed to identify independent predictors of good neurologic outcome at 90 days. Of 452 patients, 302 were enrolled. There was a significant difference among the 3 patient groups with regard to neurologic outcome at 90 days in the univariate analysis. Multiple logistic regression analyses showed that the GCS motor score on admission, age >65 years, bystander cardiopulmonary resuscitation, the time from collapse to return of spontaneous circulation, and pupil size patients sustaining out-of-hospital CA who receive TH.

  5. Na emission and bubble instability in single-bubble sonoluminescence.

    Science.gov (United States)

    Choi, Pak-Kon; Takumori, Keisuke; Lee, Hyang-Bok

    2017-09-01

    Na emission in single-bubble sonoluminescence (SBSL) was observed from 0.1mM sodium dodecyl sulfate (SDS) solution containing a dissolved noble gas at a low acoustic pressure, at which a continuous spectral component was negligible. High-speed shadowgraph movies were captured at a frame rate of 30,000fps, which indicated that bubble dancing is responsible for the Na emission. The measured bubble path length was well correlated with the Na intensity. The disintegration of a daughter bubble followed by immediate coalescence was frequently observed, which may have been the cause of the bubble dancing. A comparison of the Na spectra obtained in SBSL and multibubble SL showed that the conditions under which Na emission is generated are twofold. A narrow component was observed in the Na spectrum in SBSL, while narrow and broad components were observed in MBSL. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Two-Dimensional Numerical Simulations of Ultrasound in Liquids with Gas Bubble Agglomerates: Examples of Bubbly-Liquid-Type Acoustic Metamaterials (BLAMMs

    Directory of Open Access Journals (Sweden)

    Christian Vanhille

    2017-01-01

    Full Text Available This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding gas bubbles of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse bubble populations confined in restricted areas of a liquid have on ultrasound by calculating their nonlinear interaction. The filtering of an input ultrasonic pulse performed by a net of bubbly-liquid cells is analyzed. The generation of a low-frequency component from a single cell impinged by a two-frequency harmonic wave is also studied. These effects rely on the particular dispersive character of attenuation and nonlinearity of such bubbly fluids, which can be extremely high near bubble resonance. They allow us to observe how gas bubbles can change acoustic signals. Variations of the bubbly medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by bubbles. This capacity to achieve the modification and control of sound with oscillating gas bubbles introduces the concept of bubbly-liquid-based acoustic metamaterials (BLAMMs.

  7. The "brain-sparing" effect: antenatal cerebral Doppler findings in relation to neurologic outcome in very preterm infants

    NARCIS (Netherlands)

    Scherjon, S. A.; Smolders-DeHaas, H.; Kok, J. H.; Zondervan, H. A.

    1993-01-01

    OBJECTIVE: Our purpose was to study the relationship between fetal cerebral circulation and neurologic outcome. STUDY DESIGN: In 117 high-risk fetuses (gestational age 25 to 33 weeks) flow velocity waveforms were recorded from the umbilical and medial cerebral arteries. The ratio between umbilical

  8. Bubble size distribution in acoustic droplet vaporization via dissolution using an ultrasound wide-beam method.

    Science.gov (United States)

    Xu, Shanshan; Zong, Yujin; Li, Wusong; Zhang, Siyuan; Wan, Mingxi

    2014-05-01

    Performance and efficiency of numerous cavitation enhanced applications in a wide range of areas depend on the cavitation bubble size distribution. Therefore, cavitation bubble size estimation would be beneficial for biological and industrial applications that rely on cavitation. In this study, an acoustic method using a wide beam with low pressure is proposed to acquire the time intensity curve of the dissolution process for the cavitation bubble population and then determine the bubble size distribution. Dissolution of the cavitation bubbles in saline and in phase-shift nanodroplet emulsion diluted with undegassed or degassed saline was obtained to quantify the effects of pulse duration (PD) and acoustic power (AP) or peak negative pressure (PNP) of focused ultrasound on the size distribution of induced cavitation bubbles. It was found that an increase of PD will induce large bubbles while AP had only a little effect on the mean bubble size in saline. It was also recognized that longer PD and higher PNP increases the proportions of large and small bubbles, respectively, in suspensions of phase-shift nanodroplet emulsions. Moreover, degassing of the suspension tended to bring about smaller mean bubble size than the undegassed suspension. In addition, condensation of cavitation bubble produced in diluted suspension of phase-shift nanodroplet emulsion was involved in the calculation to discuss the effect of bubble condensation in the bubble size estimation in acoustic droplet vaporization. It was shown that calculation without considering the condensation might underestimate the mean bubble size and the calculation with considering the condensation might have more influence over the size distribution of small bubbles, but less effect on that of large bubbles. Without or with considering bubble condensation, the accessible minimum bubble radius was 0.4 or 1.7 μm and the step size was 0.3 μm. This acoustic technique provides an approach to estimate the size

  9. Improvement of ore recovery efficiency in a flotation column cell using ultra-sonic enhanced bubbles

    Science.gov (United States)

    Filippov, L. O.; Royer, J. J.; Filippova, I. V.

    2017-07-01

    The ore process flotation technique is enhanced by using external ultra-sonic waves. Compared to the classical flotation method, the application of ultrasounds to flotation fluids generates micro-bubbles by hydrodynamic cavitation. Flotation performances increase was modelled as a result of increased probabilities of the particle-bubble attachment and reduced detachment probability under sonication. A simplified analytical Navier-Stokes model is used to predict the effect of ultrasonic waves on bubble behavior. If the theory is verified by experimentation, it predicts that the ultrasonic waves would create cavitation micro-bubbles, smaller than the flotation bubble added by the gas sparger. This effect leads to increasing the number of small bubbles in the liquid which promote particle-bubble attachment through coalescence between bubbles and micro-bubbles. The decrease in the radius of the flotation bubbles under external vibration forces has an additional effect by enhancing the bubble-particle collision. Preliminary results performed on a potash ore seem to confirm the theory.

  10. Sonoporation from jetting cavitation bubbles

    NARCIS (Netherlands)

    Ohl, C.D.; Arora, M.; Ikink, Roy; de Jong, N.; Versluis, Michel; Delius, Michael; Lohse, Detlef

    2006-01-01

    The fluid dynamic interaction of cavitation bubbles with adherent cells on a substrate is experimentally investigated. We find that the nonspherical collapse of bubbles near to the boundary is responsible for cell detachment. High-speed photography reveals that a wall bounded flow leads to the

  11. Sonoporation from jetting cavitation bubbles

    NARCIS (Netherlands)

    C.-D. Ohl (Claus-Dieter); M. Arora (Manish); R. Ikink (Roy); N. de Jong (Nico); M. Versluis (Michel); M. Delius (Michael); D. Lohse (Detlef)

    2006-01-01

    textabstractThe fluid dynamic interaction of cavitation bubbles with adherent cells on a substrate is experimentally investigated. We find that the nonspherical collapse of bubbles near to the boundary is responsible for cell detachment. High-speed photography reveals that a wall bounded flow leads

  12. Bubble size distribution of foam

    NARCIS (Netherlands)

    den Engelsen, C.W.; den Engelsen, C.W.; Isarin, J.C.; Warmoeskerken, Marinus; Groot Wassink, J.; Groot Wassink, J.

    2002-01-01

    A procedure based upon image analysis has been adopted to study the influence of several physical parameters on bubble size in foam. A procedure has been described to account for the distribution of bubble size. Foam was generated in a rotor-stator mixer. In the present research, the nature of the

  13. Mr. Bubble Gum: "Not Now!"

    National Research Council Canada - National Science Library

    1989-01-01

    PreS-Gr 2-- Mr. Bubble Gum is a Level 3 book, the most difficult in this series. In four short stories of varying lengths, an older brother tells about his younger brother Eli, who "sticks to me like bubble gum...

  14. Bubble chamber: colour enhanced tracks

    CERN Multimedia

    1998-01-01

    This artistically-enhanced image of real particle tracks was produced in the Big European Bubble Chamber (BEBC). Liquid hydrogen is used to create bubbles along the paths of the particles as a piston expands the medium. A magnetic field is produced in the detector causing the particles to travel in spirals, allowing charge and momentum to be measured.

  15. Bubble columns : Structures or stability?

    NARCIS (Netherlands)

    Harteveld, W.K.

    2005-01-01

    The aim of the thesis is to contribute to the understanding of the hydrodynamics of the gravity driven bubbly flow that can be found in bubble columns. Special attention is paid to the large scale structures that have a strong impact on several key parameters such as the degree of mixing, mass and

  16. Phase diagrams for sonoluminescing bubbles

    NARCIS (Netherlands)

    Hilgenfeldt, Sascha; Lohse, Detlef; Brenner, Michael P.

    1996-01-01

    Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration versus forcing pressure state

  17. Bubble coalescence in breathing DNA

    DEFF Research Database (Denmark)

    Novotný, Tomas; Pedersen, Jonas Nyvold; Ambjörnsson, Tobias

    2007-01-01

    We investigate the coalescence of two DNA bubbles initially located at weak segments and separated by a more stable barrier region in a designed construct of double-stranded DNA. The characteristic time for bubble coalescence and the corresponding distribution are derived, as well...

  18. Focal neurological deficits

    Science.gov (United States)

    ... or head Electromyogram (EMG), nerve conduction velocities (NCV) MRI of the back, neck, or head Spinal tap Alternative Names Neurological deficits - focal Images Brain References Daroff RB, Jankovic ...

  19. High-speed imaging of an ultrasound-driven bubble in contact with a wall: ``Narcissus'' effect and resolved acoustic streaming

    Science.gov (United States)

    Marmottant, Philippe; Versluis, Michel; de Jong, Nico; Hilgenfeldt, Sascha; Lohse, Detlef

    2006-08-01

    We report microscopic observations of the primary flow oscillation of an acoustically driven bubble in contact with a wall, captured with the ultra high-speed camera Brandaris 128 (Chin et al. 2003). The driving frequency is up to 200 kHz, and the imaging frequency is up to 25 MHz. The details of the bubble motion during an ultrasound cycle are thus resolved, showing a combination of two modes of oscillations: a radius oscillation and a translation oscillation, perpendicular to the wall. This motion is interpreted using the theory of acoustic images to account for the presence of the wall. We conclude that the bubble is subjected to a periodic succession of attractive and repulsive forces, exerted by its own image. Fast-framing recordings of a tracer particle embedded in the liquid around the particle are performed. They fully resolve the acoustic streaming flow induced by the bubble oscillations. This non-linear secondary flow appears as a tiny drift of the particle position cycle after cycle, on top of the primary back and forth oscillation. The high oscillation frequency accounts for a fast average particle velocity, with characteristic timescales in the millisecond range at the lengthscale of the bubble. The features of the bubble motion being resolved, we can apply the acoustic streaming theory near a wall, which provides predictions in agreement with the observed streaming velocity.

  20. Growing bubbles rising in line

    Directory of Open Access Journals (Sweden)

    John F. Harper

    2001-01-01

    Full Text Available Over many years the author and others have given theories for bubbles rising in line in a liquid. Theory has usually suggested that the bubbles will tend towards a stable distance apart, but experiments have often showed them pairing off and sometimes coalescing. However, existing theory seems not to deal adequately with the case of bubbles growing as they rise, which they do if the liquid is boiling, or is a supersaturated solution of a gas, or simply because the pressure decreases with height. That omission is now addressed, for spherical bubbles rising at high Reynolds numbers. As the flow is then nearly irrotational, Lagrange's equations can be used with Rayleigh's dissipation function. The theory also works for bubbles shrinking as they rise because they dissolve.

  1. The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps

    OpenAIRE

    Majumdar, Suman; Bharadwaj, Somnath; Datta, Kanan K.; Choudhury, T. Roy

    2010-01-01

    The detection of ionized bubbles around quasars in redshifted 21-cm maps is possibly one of the most direct future probes of reionization. We consider two models for the growth of spherical ionized bubbles to study the apparent shapes of the bubbles in redshifted 21-cm maps, taking into account the finite light travel time (FLTT) across the bubble. We find that the FLTT, whose effect is particularly pronounced for large bubbles, causes the bubble's image to continue to grow well after it's ac...

  2. Luminescence of transient single cavitation bubbles in non-aqueous liquids produced by the modified tube-arrest method

    Science.gov (United States)

    Wu, Xian-Mei; Ying, Chong-Fu; Li, Chao

    2005-05-01

    Large transient single bubbles of effective diameters in centimetres were generated by the modified tube-arrest method in 7 nonaqueous liquids besides water and in glycerin-water mixtures. During collapse, nearly all these bubbles gave off light emissions of various intensities, which in 6 liquids were correlated with the saturation vapour pressure and viscosity of the respective liquid. Bubbles in ethylene glycol and propylene glycol did not follow this rule, but those in the former liquid showed some unusual regularity in luminescence variation and the bubbles in both the liquids were particularly bright. The luminous properties of the transient single bubble are compared with those of the usual stable single bubble.

  3. Laboratory investigation of the factors impact on bubble size, pore blocking and enhanced oil recovery with aqueous Colloidal Gas Aphron

    National Research Council Canada - National Science Library

    Shi, Shenglong; Wang, Yefei; Li, Zhongpeng; Chen, Qingguo; Zhao, Zenghao

    ...; it is also designed to block porous media with micro-bubbles. In this paper, the effects of surfactant concentration, polymer concentration, temperature and salinity on the bubble size of the Colloidal Gas Aphron were studied...

  4. Optical and Acoustic Observations of Bubble Adhered to Piezoelectric Transducer under Ultrasound Field: Pressure Signal Caused by Bubble Behavior

    Science.gov (United States)

    Nakatani, Shintaro; Yoshida, Kenji; Watanabe, Yoshiaki

    2008-05-01

    In order to clarify the mechanical effects caused by micro-bubbles in liquids, the detailed behavior of a single bubble adhered to a solid surface was observed optically using an ultra high-speed video camera (maximum recording rate: 1,000,000 frames/s). Making use of a thin piezoelectric transducer on the solid surface, the pressure signal caused by the bubble behavior was simultaneously observed. In addition, the influence of the initial bubble radius R0 on mechanical effects was investigated. It was confirmed that a micro-jet was generated from the center of the bubble, which was followed by a counter-jet, in the range of R0/Rres≈0.65-1.10 (Rres: the resonance radius of the free bubble). An impulsive positive pressure to the surface was also observed synchronously with the momentary increase of bubble volume acceleration. Moreover, it was found that the strength of the impulsive pressure was connected to the peak value of volume acceleration. The pressure amplitude showed a maximum value when R0/Rres was approximately 0.9.

  5. Neurology advanced practice providers: A position paper of the American Academy of Neurology.

    Science.gov (United States)

    Schwarz, Heidi B; Fritz, Joseph V; Govindarajan, Raghav; Penfold Murray, Rebecca; Boyle, Kathryn B; Getchius, Thomas S D; Freimer, Miriam

    2015-08-01

    There are many factors driving health care reform, including unsustainable costs, poor outcomes, an aging populace, and physician shortages. These issues are particularly relevant to neurology. New reimbursement models are based on value and facilitated by the use of multidisciplinary teams. Integration of advanced practice providers (APPs) into neurology practice offers many advantages with new models of care. Conversely, there are many and varied challenges financially and logistically with these practice models. The American Academy of Neurology has formed a Work Group to address the needs of both neurologists and neurologic APPs and monitor the effect of APPs on quality and cost of neurologic care.

  6. Dynamics of Subcritical Bubbles in First Order Phase Transition

    Science.gov (United States)

    Shiromizu, T.; Morikawa, M.; Yokoyama, J.

    1995-11-01

    We derivate the Langevin and the Fokker-Planck equations for the radius of O(3)-symmetric subcritical bubbles as a phenomenological model to treat thermal fluctuation. The effect of thermal noise on subcritical bubbles is examined. We find that the fluctuation-dissipation relation holds and that in the high temperature phase the system settles down rapidly to the thermal equilibrium state even if it was in a nonequilibrium state initially. We then estimate the typical size of subcritical bubbles as well as the amplitude of fluctuations on that scale. We also discuss their implication to the electroweak phase transition.

  7. Oscillation of a diamagnetic liquid bubble suspended by magnetic force

    Energy Technology Data Exchange (ETDEWEB)

    Yamane, R. E-mail: yamane@kokushikan.ac.jp; Tomita, S.; Mai, J.; Park, M.K.; Oshima, S

    2002-11-01

    The levitation of the diamagnetic liquid droplet with the strong magnetic field is experimentally simulated, using the magnetic fluid as the surrounding fluid in place of air or gas, and the water bubble is levitated with the conventional permanent magnet. When the stepwise magnetic field is superposed, the suspended bubble behaves as a typical step response with the overshoot and viscous damping. The effects of the volume of the bubble, the strength of the magnetic field and the concentration of the magnetic fluid are investigated.

  8. Study on the bubble transport mechanism in an acoustic standing wave field.

    Science.gov (United States)

    Xi, Xiaoyu; Cegla, Frederic B; Lowe, Michael; Thiemann, Andrea; Nowak, Till; Mettin, Robert; Holsteyns, Frank; Lippert, Alexander

    2011-12-01

    The use of bubbles in applications such as surface chemistry, drug delivery, and ultrasonic cleaning etc. has been enormously popular in the past two decades. It has been recognized that acoustically-driven bubbles can be used to disturb the flow field near a boundary in order to accelerate physical or chemical reactions on the surface. The interactions between bubbles and a surface have been studied experimentally and analytically. However, most of the investigations focused on violently oscillating bubbles (also known as cavitation bubble), less attention has been given to understand the interactions between moderately oscillating bubbles and a boundary. Moreover, cavitation bubbles were normally generated in situ by a high intensity laser beam, little experimental work has been carried out to study the translational trajectory of a moderately oscillating bubble in an acoustic field and subsequent interactions with the surface. This paper describes the design of an ultrasonic test cell and explores the mechanism of bubble manipulation within the test cell. The test cell consists of a transducer, a liquid medium and a glass backing plate. The acoustic field within the multi-layered stack was designed in such a way that it was effectively one dimensional. This was then successfully simulated by a one dimensional network model. The model can accurately predict the impedance of the test cell as well as the mode shape (distribution of particle velocity and stress/pressure field) within the whole assembly. The mode shape of the stack was designed so that bubbles can be pushed from their injection point onto a backing glass plate. Bubble radial oscillation was simulated by a modified Keller-Miksis equation and bubble translational motion was derived from an equation obtained by applying Newton's second law to a bubble in a liquid medium. Results indicated that the bubble trajectory depends on the acoustic pressure amplitude and initial bubble size: an increase of

  9. Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

    Science.gov (United States)

    Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

    2014-07-01

    The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Can airborne ultrasound monitor bubble size in chocolate?

    Science.gov (United States)

    Watson, N.; Hazlehurst, T.; Povey, M.; Vieira, J.; Sundara, R.; Sandoz, J.-P.

    2014-04-01

    Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product.

  11. Functional neurological disorders: imaging.

    Science.gov (United States)

    Voon, V

    2014-10-01

    Functional neurological disorders, also known as conversion disorder, are unexplained neurological symptoms. These symptoms are common and can be associated with significant consequences. This review covers the neuroimaging literature focusing on functional motor symptoms including motor functioning and upstream influences including self-monitoring and internal representations, voluntariness and arousal and trauma. Copyright © 2014. Published by Elsevier SAS.

  12. Neurological Complications of AIDS

    Science.gov (United States)

    ... the National Library of Medicine’s MedlinePlus Living with HIV/AIDS × What research is being done? The National Institute of Neurological ... the National Library of Medicine’s MedlinePlus Living with HIV/AIDS See More About Research The National Institute of Neurological Disorders and Stroke ( ...

  13. Evidence of speculative bubbles on the BOVESPA: an application of the Kalman filter

    Directory of Open Access Journals (Sweden)

    Thiago Bergmann de Queiroz

    2011-06-01

    Full Text Available The existence of bubbles in asset prices is a matter of great importance to governments and investors due to possible serious effects they may have on economies. In the case of shares, the presence of a price bubble can be seen by comparing prices and dividends in the long run. This study aimed to assess the occurrence of price bubbles in the Brazilian stock market, by comparing the IBOVESPA as price index and an index of dividends, built based on the methodology of IBOVESPA. The bubble was considered a unobserved state vector in a state-space model and was estimated using the Kalman filter. The results were compared with the standard present value model and intrinsic bubbles model (Froot e Obstfeld, 1991. Although the model establishes the presence of bubbles, the intrinsic bubbles model (Froot e Obstfeld, 1991 showed similar results with greater accuracy.

  14. Effects of 14 Versus 21 Days of Nimodipine Therapy on Neurological Outcomes in Aneurysmal Subarachnoid Hemorrhage Patients.

    Science.gov (United States)

    Cho, Susan; Bales, James; Tran, Thao Kim; Korab, Gina; Khandelwal, Nita; Joffe, Aaron M

    2016-09-01

    Oral nimodipine is standard therapy for patients suffering an aneurysmal subarachnoid hemorrhage (aSAH). During a national drug shortage, nimodipine therapy was shortened from a 21-day course to a 14-day course at our institution. The objective of this study was to compare neurological outcomes among patients who had previously received the standard duration of therapy compared with those who received a shortened duration as a result of the national drug shortage. This retrospective cohort study evaluated adult patients receiving nimodipine for aSAH from January 2012 to August 2013. Neurological outcome, graded by Modified Rankin Scale (mRS) at hospital discharge, was compared between patients receiving a shortened course and those receiving the standard duration of nimodipine. A total of 199 aSAH patients were included in the analysis. There were 164 patients in the standard-duration and 35 patients in the shortened-duration group. Baseline patient severity of illness, assessed by SAPS II (Simplified Acute Physiology Score), and severity of aSAH, assessed by Fisher grade, and Hunt and Hess grade scores, did not differ between the treatment groups. A shortened duration of nimodipine was not associated with a higher risk of a poor neurological outcome defined by mRS (odds ratio = 1.85; 95% CI = 0.54-6.32; P = 0.32). Mortality rates were similar between the groups. A 14-day course of nimodipine therapy was not associated with worse neurological outcomes in aSAH patients at one institution. More studies are needed prior to recommending a shortened duration of nimodipine therapy in all aSAH patients. © The Author(s) 2016.

  15. Congenital and inherited neurologic diseases in dogs and cats: Legislation and its effect on purchase in Italy.

    Science.gov (United States)

    Passantino, Annamaria; Masucci, Marisa

    2016-05-01

    Many of the congenital neurologic diseases can result in incapacity or death of the animal. Some of them, such as idiopathic epilepsy and hydrocephalus, exhibit breed or familial predisposition and a genetic basis was proved or suggested. Some diseases can be presumptively diagnosed after a detailed signalment (breed predisposition), history (e.g. family history because many of these defects have familial tendencies), and through physical exam; other diagnostic methods (radiography, computed tomography, magnetic resonance, electrophysiologic tests, etc.) can provide supportive evidence for the congenital defect and help to confirm the diagnosis. Some cases can lead to civil law-suits when the lesions are congenital, but not easily recognizable, or when the lesions are hereditary but tend to became manifest only after some time (more than 12 months after the date of purchase, e.g., after the vice-free guarantee period has expired). Moreover, quite frequently an early diagnosis is not made because there are delays in consulting the veterinarian or the general practitioner veterinarian does not perceive subtle signs. This study was designed to focus on the medico-legal aspects concerning the buying and selling in Italy of dogs and cats affected by congenital and hereditary neurologic diseases that could constitute vice in these animals. While adequate provisions to regulate in detail the various aspects of pet sale have still to be drawn up by legislators, it may be helpful to involve breeders, by obliging them by contract to extend guarantees in the case of hereditary lesions, including neurologic diseases.

  16. Expanding the neurological examination using functional neurologic assessment: part II neurologic basis of applied kinesiology.

    Science.gov (United States)

    Schmitt, W H; Yanuck, S F

    1999-03-01

    Functional Neurologic Assessment and treatment methods common to the practice of applied kinesiology are presented. These methods are proposed to enhance neurological examination and treatment procedures toward more effective assessment and care of functional impairment. A neurologic model for these procedures is proposed. Manual assessment of muscular function is used to identify changes associated with facilitation and inhibition, in response to the introduction of sensory receptor-based stimuli. Muscle testing responses to sensory stimulation of known value are compared with usually predictable patterns based on known neuroanatomy and neurophysiology, guiding the clinician to an understanding of the functional status of the patient's nervous system. These assessment procedures are used in addition to other standard diagnostic measures to augment rather than replace the existing diagnostic armamentarium. The proper understanding of the neurophysiologic basis of muscle testing procedures will assist in the design of further investigations into applied kinesiology. Accordingly, the neurophysiologic basis and proposed mechanisms of these methods are reviewed.

  17. The bubble legacy

    Science.gov (United States)

    Hecht, Jeff

    2010-05-01

    Imagine an optics company - let's call it JDS Uniphase - with a market capitalization approaching the gross domestic product (GDP) of Ireland. Now imagine it merging with a laser company - say, SDL - that has a stock valuation of 41bn, higher than the GDP of Costa Rica. Finally, imagine a start-up with 109m in venture capital in its pocket but no product to its name (Novalux) turning down an offer of 500m as insufficient. It may be hard to believe, but these tales are true: they occurred in the year 2000 - an era when the laser, fibre-optics and photonics industries were the darlings of the financial world. Such was the madcap nature of that brief period that survivors call it simply "the bubble".

  18. Experimental Investigation of the Interaction between Rising Bubbles and Swirling Water Flow

    Directory of Open Access Journals (Sweden)

    Tomomi Uchiyama

    2014-01-01

    Full Text Available This study experimentally investigates the interaction between rising bubbles and swirling water flow imposed around the central (vertical axis of a bubble plume in a cylindrical water tank. Small air bubbles are successively released from the bottom of the tank to generate a bubble plume, and a stirring disc at the bottom of the tank is rotated to impose a swirling water flow around the central axis of the bubble plume. The bubbles disperse further with the increasing rotational speed ω of the stirring disc. Some bubbles shift toward the central axis of the swirling flow when ω is high. The nondimensional swirling velocity of water reduces with increasing bubble flow rate when ω is lower than a certain value. However, it is less affected by the bubbles when ω is higher. The precessional amplitude for the upper end of the vortex core increases due to the presence of the bubbles. With increasing ω, the nondimensional precessional velocity decreases, and the bubble effect also reduces.

  19. Spontaneous and Directional Bubble Transport on Porous Copper Wires with Complex Shapes in Aqueous Media.

    Science.gov (United States)

    Li, Wenjing; Zhang, Jingjing; Xue, Zhongxin; Wang, Jingming; Jiang, Lei

    2018-01-24

    Manipulation of gas bubble behaviors is crucial for gas bubble-related applications. Generally, the manipulation of gas bubble behaviors generally takes advantage of their buoyancy force. It is very difficult to control the transportation of gas bubbles in a specific direction. Several approaches have been developed to collect and transport bubbles in aqueous media; however, most reliable and effective manipulation of gas bubbles in aqueous media occurs on the interfaces with simple shapes (i.e., cylinder and cone shapes). Reliable strategies for spontaneous and directional transport of gas bubbles on interfaces with complex shapes remain enormously challenging. Herein, a type of 3D gradient porous network was constructed on copper wire interfaces, with rectangle, wave, and helix shapes. The superhydrophobic copper wires were immersed in water, and continuous and stable gas films then formed on the interfaces. With the assistance of the Laplace pressure gradient between two bubbles, gas bubbles (including microscopic gas bubbles) in the aqueous media were subsequently transported, continuously and directionally, on the copper wires with complex shapes. The small gas bubbles always moved to the larger ones.

  20. An investigation into neurologic and neurobehavioral effects of long-term agrichemical use among deciduous fruit farm workers in the Western Cape, South Africa.

    Science.gov (United States)

    London, L; Myers, J E; Nell, V; Taylor, T; Thompson, M L

    1997-01-01

    Long-term exposure to organophosphates (OPs) in the absence of acute poisoning is increasingly suspected of causing chronic neurologic and neurobehavioral effects. A cross-sectional survey of 163 spray operators on deciduous fruit farms in the Western Cape, South Africa, and 84 nonspraying labororers was conducted in 1993 to investigate the relationship between long-term OP exposures and neurological and neurobehavioral outcomes. The study also sought to evaluate the performance of a set of neurobehavioral test batteries based on the information-processing theory of cognitive psychology, relative to the more established World Health Organization's Neurobehavioral Core Test Battery (WHO NCTB). These information-processing tests were designed for use in studies of subjects with little education, which are frequently conducted in developing countries in agriculture. They draw on experience from a previous South African study in which problems were encountered with a lack of cross-cultural validity of conventional test batteries. No evidence was found of a relationship between long-term OP exposure and loss of vibration sense. Small associations were found with the NCTB Pursuit-Aiming and Santa Ana (nondominant hand) subtests. The overall evidence of neurologic and neurobehavioral effects of long-term OP exposure was small; exposure misclassification may have contributed to this finding. Important confounders such as brain injury, alcohol consumption, and nutritional status were identified. Copyright 1997 Academic Press.

  1. Numerical Study of Bubble Area Evolution During Acoustic Droplet Vaporization-Enhanced HIFU Treatment.

    Science.gov (United States)

    Xin, Ying; Zhang, Aili; Xu, Lisa X; Brian Fowlkes, J

    2017-09-01

    Acoustic droplet vaporization has the potential to shorten treatment time of high-intensity focused ultrasound (HIFU) while minimizing the possible effects of microbubbles along the propagation path. Distribution of the bubbles formed from the droplets during the treatment is the major factor shaping the therapeutic region. A numerical model was proposed to simulate the bubble area evolution during this treatment. Using a linear acoustic equation to describe the ultrasound field, a threshold range was defined that determines the amount of bubbles vaporized in the treated area. Acoustic parameters, such as sound speed, acoustic attenuation coefficient, and density, were treated as a function of the bubble size distribution and the gas void fraction, which were related to the vaporized bubbles in the medium. An effective pressure factor was proposed to account for the influence of the existing bubbles on the vaporization of the nearby droplets. The factor was obtained by fitting one experimental result and was then used to calculate bubble clouds in other experimental cases. Comparing the simulation results to these other experiments validated the model. The dynamic change of the pressure and the bubble distribution after exposure to over 20 pulses of HIFU are obtained. It is found that the bubble area grows from a grainlike shape to a "tadpole," with comparable dimensions and shape to those observed in experiments. The process was highly dynamic with the shape of the bubble area changing with successive HIFU pulses and the focal pressure. The model was further used to predict the shape of the bubble region triggered by HIFU when a bubble wall pre-exists. The results showed that the bubble wall helps prevent droplet vaporization on the distal side of the wall and forms a particularly shaped region with bubbles. This simulation model has predictive potential that could be beneficial in applications, such as cancer treatment, by parametrically studying conditions

  2. Bubble size distribution and inner surface in a bubble flow

    Science.gov (United States)

    Žitek, P.; Valenta, V.

    2017-09-01

    This paper follows the reports [4] and gives instructions on how to theoretically determine the bubble size and its distribution using the distribution function of Nukiyama-Tanasawa with friction factors.

  3. Observational Study of Prevalence of Long-term Raynaud-Like Phenomena and Neurological Side Effects in Testicular Cancer Survivors

    Science.gov (United States)

    Oldenburg, Jan; Klepp, Olbjørn; Bremnes, Roy M.; Wist, Erik A.; Wentzel-Larsen, Tore; Hauge, Erik R.; Dahl, Olav; Fosså, Sophie D.

    2009-01-01

    cold exposure), 29% (95% CI = 25% to 33%) reported paresthesias in the hands or feet, 21% (95% CI = 18% to 25%) reported hearing impairment, and 22% (95% CI = 19% to 26%) reported tinnitus as major symptoms troubling them quite a bit or very much. Hearing impairment (odds ratio [OR] = 5.3, 95% CI = 3.0 to 9.2) and tinnitus (OR = 7.1, 95% CI = 4.1 to 12.4) were particularly common in the dose-intensive chemotherapy group compared with the no chemotherapy group. Men who were treated with radiotherapy had higher odds of self-reported paresthesias in feet compared with those not treated with radiotherapy (OR = 1.5, 95% CI = 1.01 to 2.1, P = .04). Conclusion Long-term survivors of testicular cancer who were treated with cisplatin-based chemotherapy were more often troubled by dose-dependent neurological side effects and Raynaud-like phenomena compared with those who were not treated with chemotherapy. PMID:19940282

  4. Sonochemistry and the acoustic bubble

    CERN Document Server

    Grieser, Franz; Enomoto, Naoya; Harada, Hisashi; Okitsu, Kenji; Yasui, Kyuichi

    2015-01-01

    Sonochemistry and the Acoustic Bubble provides an introduction to the way ultrasound acts on bubbles in a liquid to cause bubbles to collapse violently, leading to localized 'hot spots' in the liquid with temperatures of 5000° celcius and under pressures of several hundred atmospheres. These extreme conditions produce events such as the emission of light, sonoluminescence, with a lifetime of less than a nanosecond, and free radicals that can initiate a host of varied chemical reactions (sonochemistry) in the liquid, all at room temperature. The physics and chemistry behind the p

  5. Partial coalescence of soap bubbles

    Science.gov (United States)

    Harris, Daniel M.; Pucci, Giuseppe; Bush, John W. M.

    2015-11-01

    We present the results of an experimental investigation of the merger of a soap bubble with a planar soap film. When gently deposited onto a horizontal film, a bubble may interact with the underlying film in such a way as to decrease in size, leaving behind a smaller daughter bubble with approximately half the radius of its progenitor. The process repeats up to three times, with each partial coalescence event occurring over a time scale comparable to the inertial-capillary time. Our results are compared to the recent numerical simulations of Martin and Blanchette and to the coalescence cascade of droplets on a fluid bath.

  6. New evidence on the first financial bubble

    NARCIS (Netherlands)

    Frehen, R.G.P.; Goetzmann, W.; Rouwenhorst, K.G.

    2013-01-01

    The Mississippi Bubble, South Sea Bubble and the Dutch Windhandel of 1720 together represent the world's first global financial bubble. We hand-collect cross-sectional price data and investor account data from 1720 to test theories about market bubbles. Our tests suggest that innovation was a key

  7. Neurological and neurosurgical manifestations of human ...

    African Journals Online (AJOL)

    adults in Abidjan, Cote d'Ivoire and in Kinshasa and among inpatients in Ugandan hospitals. Ninety per cent of deaths ... various parts of the continent. Neurological manifestations. The spectrum of neurological diseases reported in ... Primary effects of HIV. HEADACHE. Case report. A Malawian 46-year-old male senior ...

  8. High-speed visualization and radiated pressure measurement of a laser-induced gas bubble in glycerin-water solutions

    Science.gov (United States)

    Nakajima, Takehiro; Kondo, Tomoki; Ando, Keita

    2016-11-01

    We study the dynamics of a spherical gaseous bubble created by focusing a nanosecond laser pulse at 532 nm into a large volume of glycerin-water solutions. Free oscillation of the bubble and shock wave emission from the bubble dynamics are recorded by a high-speed camera together with a pulse laser stroboscope; concurrently, pressure radiated from the oscillating bubble is measured by a hydrophone. The bubble achieves a mechanical equilibrium after free oscillation is damped out; the equilibrium state stays for a while, unlike vapor bubbles. We speculate that the bubble content is mainly gases originally dissolved in the liquid (i.e., air). The bubble dynamics we observed are compared to Rayleigh-Plesset-type calculations that account for diffusive effects; the (unknown) initial pressure just after laser focusing is tuned to obtain agreement between the experiment and the calculation. Moreover, viscous effects on the shock propagation are examined with the aid of compressible Navier-Stokes simulation.

  9. A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment

    Science.gov (United States)

    McQuillen, J.

    2000-01-01

    The influence of gravity on the two-phase flow dynamics is obvious.As the gravity level is reduced,there is a new balance between inertial and interfacial forces, altering the behavior of the flow. In bubbly flow,the absence of drift velocity leads to spherical-shaped bubbles with a rectilinear trajectory.Slug flow is a succession of long bubbles and liquid slug carrying a few bubbles. There is no flow reversal in the thin liquid film as the long bubble and liquid slug pass over the film. Although the flow structure seems to be simpler than in normal gravity conditions,the models developed for the prediction of flow behavior in normal gravity and extended to reduced gravity flow are unable to predict the flow behavior correctly.An additional benefit of conducting studies in microgravity flows is that these studies aide the development of understanding for normal gravity flow behavior by removing the effects of buoyancy on the shape of the interface and density driven shear flows between the gas and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated bubbles in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated bubbles and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the bubbles in accelerated or decelerated flows,and the dynamics of isolated cylindrical bubbles, their deformation in accelerated/decelerated flows (in converging or diverging channels), and bubble/bubble interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical bubble and single and two cylindrical bubble behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of bubbly and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from bubbly to slug flow (effect of fluid properties and

  10. Neurologic complications of vaccinations.

    Science.gov (United States)

    Miravalle, Augusto A; Schreiner, Teri

    2014-01-01

    This chapter reviews the most common neurologic disorders associated with common vaccines, evaluates the data linking the disorder with the vaccine, and discusses the potential mechanism of disease. A literature search was conducted in PubMed using a combination of the following terms: vaccines, vaccination, immunization, and neurologic complications. Data were also gathered from publications of the American Academy of Pediatrics Committee on Infectious Diseases, the World Health Organization, the US Centers for Disease Control and Prevention, and the Vaccine Adverse Event Reporting System. Neurologic complications of vaccination are rare. Many associations have been asserted without objective data to support a causal relationship. Rarely, patients with a neurologic complication will have a poor outcome. However, most patients recover fully from the neurologic complication. Vaccinations have altered the landscape of infectious disease. However, perception of risk associated with vaccinations has limited the success of disease eradication measures. Neurologic complications can be severe, and can provoke fear in potential vaccines. Evaluating whether there is causal link between neurologic disorders and vaccinations, not just temporal association, is critical to addressing public misperception of risk of vaccination. Among the vaccines available today, the cost-benefit analysis of vaccinations and complications strongly argues in favor of vaccination. © 2014 Elsevier B.V. All rights reserved.

  11. Cardiomyopathy in neurological disorders.

    Science.gov (United States)

    Finsterer, Josef; Stöllberger, Claudia; Wahbi, Karim

    2013-01-01

    According to the American Heart Association, cardiomyopathies are classified as primary (solely or predominantly confined to heart muscle), secondary (those showing pathological myocardial involvement as part of a neuromuscular disorder) and those in which cardiomyopathy is the first/predominant manifestation of a neuromuscular disorder. Cardiomyopathies may be further classified as hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, or unclassified cardiomyopathy (noncompaction, Takotsubo-cardiomyopathy). This review focuses on secondary cardiomyopathies and those in which cardiomyopathy is the predominant manifestation of a myopathy. Any of them may cause neurological disease, and any of them may be a manifestation of a neurological disorder. Neurological disease most frequently caused by cardiomyopathies is ischemic stroke, followed by transitory ischemic attack, syncope, or vertigo. Neurological disease, which most frequently manifests with cardiomyopathies are the neuromuscular disorders. Most commonly associated with cardiomyopathies are muscular dystrophies, myofibrillar myopathies, congenital myopathies and metabolic myopathies. Management of neurological disease caused by cardiomyopathies is not at variance from the same neurological disorders due to other causes. Management of secondary cardiomyopathies is not different from that of cardiomyopathies due to other causes either. Patients with neuromuscular disorders require early cardiologic investigations and close follow-ups, patients with cardiomyopathies require neurological investigation and avoidance of muscle toxic medication if a neuromuscular disorder is diagnosed. Which patients with cardiomyopathy profit most from primary stroke prevention is unsolved and requires further investigations. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Recombinant Tissue Plasminogen Activator Induces Neurological Side Effects Independent on Thrombolysis in Mechanical Animal Models of Focal Cerebral Infarction: A Systematic Review and Meta-Analysis.

    Directory of Open Access Journals (Sweden)

    Mei-Xue Dong

    Full Text Available Recombinant tissue plasminogen activator (rtPA is the only effective drug approved by US FDA to treat ischemic stroke, and it contains pleiotropic effects besides thrombolysis. We performed a meta-analysis to clarify effect of tissue plasminogen activator (tPA on cerebral infarction besides its thrombolysis property in mechanical animal stroke.Relevant studies were identified by two reviewers after searching online databases, including Pubmed, Embase, and ScienceDirect, from 1979 to 2016. We identified 6, 65, 17, 12, 16, 12 and 13 comparisons reporting effect of endogenous tPA on infarction volume and effects of rtPA on infarction volume, blood-brain barrier, brain edema, intracerebral hemorrhage, neurological function and mortality rate in all 47 included studies. Standardized mean differences for continuous measures and risk ratio for dichotomous measures were calculated to assess the effects of endogenous tPA and rtPA on cerebral infarction in animals. The quality of included studies was assessed using the Stroke Therapy Academic Industry Roundtable score. Subgroup analysis, meta-regression and sensitivity analysis were performed to explore sources of heterogeneity. Funnel plot, Trim and Fill method and Egger's test were obtained to detect publication bias.We found that both endogenous tPA and rtPA had not enlarged infarction volume, or deteriorated neurological function. However, rtPA would disrupt blood-brain barrier, aggravate brain edema, induce intracerebral hemorrhage and increase mortality rate.This meta-analysis reveals rtPA can lead to neurological side effects besides thrombolysis in mechanical animal stroke, which may account for clinical exacerbation for stroke patients that do not achieve vascular recanalization with rtPA.

  13. Aspherical bubble dynamics and oscillation times

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, A.; Noack, J. [Meizinisches Laserzentrum Luebeck (Germany); Chapyak, E.J.; Godwin, R.P. [Los Alamos National Lab., NM (United States)

    1999-06-01

    The cavitation bubbles common in laser medicine are rarely perfectly spherical and are often located near tissue boundaries, in vessels, etc., which introduce aspherical dynamics. Here, novel features of aspherical bubble dynamics are explored by time-resolved photography and numerical simulations. The growth-collapse period of cylindrical bubbles of large aspect ratio (length:diameter {approximately}20) differs only slightly from twice the Rayleigh collapse time for a spherical bubble with an equivalent maximum volume. This fact justifies using the temporal interval between the acoustic signals emitted upon bubble creation and collapse to estimate the maximum bubble volume. As a result, hydrophone measurements can provide an estimate of the bubble size and energy even for aspherical bubbles. The change of the oscillation period of bubbles near solid walls and elastic (tissue-like) boundaries relative to that of isolated spherical bubbles is also investigated.

  14. Effects of conventional neurological treatment and a virtual reality training program on eye-hand coordination in children with cerebral palsy.

    Science.gov (United States)

    Shin, Ji-Won; Song, Gui-Bin; Hwangbo, Gak

    2015-07-01

    [Purpose] The purpose of the study was to evaluate the effects of conventional neurological treatment and a virtual reality training program on eye-hand coordination in children with cerebral palsy. [Subjects] Sixteen children (9 males, 7 females) with spastic diplegic cerebral palsy were recruited and randomly assigned to the conventional neurological physical therapy group (CG) and virtual reality training group (VRG). [Methods] Eight children in the control group performed 45 minutes of therapeutic exercise twice a week for eight weeks. In the experimental group, the other eight children performed 30 minutes of therapeutic exercise and 15 minutes of a training program using virtual reality twice a week during the experimental period. [Results] After eight weeks of the training program, there were significant differences in eye-hand coordination and visual motor speed in the comparison of the virtual reality training group with the conventional neurological physical therapy group. [Conclusion] We conclude that a well-designed training program using virtual reality can improve eye-hand coordination in children with cerebral palsy.

  15. Effective Suckling C57BL/6, Kunming, and BALB/c Mouse Models with Remarkable Neurological Manifestation for Zika Virus Infection.

    Science.gov (United States)

    Yu, Jianhai; Liu, Xuling; Ke, Changwen; Wu, Qinghua; Lu, Weizhi; Qin, Zhiran; He, Xiaoen; Liu, Yujing; Deng, Jieli; Xu, Suiqi; Li, Ying; Zhu, Li; Wan, Chengsong; Zhang, Qiwei; Xiao, Weiwei; Xie, Qian; Zhang, Bao; Zhao, Wei

    2017-06-29

    Since 2015, 84 countries and territories reported evidence of vector-borne Zika Virus (ZIKV) transmission. The World Health Organization (WHO) declared that ZIKV and associated consequences especially the neurological autoimmune disorder Guillain-Barré syndrome (GBS) and microcephaly will remain a significant enduring public health challenge requiring intense action. We apply a standardization of the multi-subcutaneous dorsal inoculation method to systematically summarize clinical neurological manifestation, viral distribution, and tissue damage during the progress of viremia and systemic spread in suckling mouse models. We found that C57BL/6 and Kunming mice (KM) both showed remarkable and uniform neurologic manifestations. C57BL/6 owned the highest susceptibility and pathogenicity to the nervous system, referred to as movement disorders, with 100% incidence, while KM was an economic model for a Chinese study characterized by lower limb weakness with 62% morbidity. Slight yellow extraocular exudates were observed in BALB/c, suggesting the association with similar ocular findings to those of clinical cases. The virus distribution and pathological changes in the sera, brains, livers, kidneys, spleens, and testes during disease progression had strong regularity and uniformity, demonstrating the effectiveness and plasticity of the animal models. The successful establishment of these animal models will be conducive to expound the pathogenic mechanism of GBS.

  16. Automatic external defibrillation and its effects on neurologic outcome in cardiac arrest patients in an urban, two-tiered EMS system.

    Science.gov (United States)

    Ho, J; Held, T; Heegaard, W; Crimmins, T

    1997-01-01

    To describe the use of the Automatic External Defibrillation (AED) device in an urban, two-tiered Emergency Medical Service (EMS) response setting with regard to its potential effects on cardiac arrest patient survival and neurologic outcome. A retrospective and descriptive design was utilized to study all cardiac arrest patients that had resuscitations attempted in the prehospital environment over a 30-month period. The study took place in a two-tiered EMS system serving an urban population of 368,383 persons. The first tier of EMS response is provided by the City Fire Department, which is equipped with a standard AED device. All first-tier personnel are trained to the level of Emergency Medical Technician-Basic. The second tier of EMS response is provided by personnel from one of two ambulance services. All second-tier personnel are trained to the level of Emergency Medical Technician-Paramedic. 271 cardiac arrest patients were identified for inclusion. One-hundred nine of these patients (40.2%) had an initial rhythm of either ventricular fibrillation or pulseless ventricular tachycardia and were shocked using the AED upon the arrival of first-tier personnel. Forty-two patients (38.5%) in this group had a return of spontaneous circulation in the field and 22 (20.2%) survived to hospital discharge. Of the survivors, 17 (77.3%) had moderate to good neurologic function at discharge based on the Glasgow-Pittsburgh Cerebral Performance Categories. Faster response times by the first-tier personnel appeared to correlate with better neurologic outcomes. First responder-based AED usage on patients in ventricular fibrillation or pulseless ventricular tachycardia can be applied successfully in an urban setting utilizing a two-tiered EMS response. In this study, a 20.2% survival to hospital discharge rate was obtained. Seventy-seven percent of these survivors had a moderate to good neurologic outcome based on the Glasgow-Pittsburgh Cerebral Performance Categories.

  17. Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer.

    Science.gov (United States)

    Lim, Ho-Joon; Chang, Kuang-An; Su, Chin B; Chen, Chi-Yueh

    2008-12-01

    A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the underestimated measurement value. Velocity information is accurately obtained from the reflected signals before the fiber tip touches the bubble surface so that several factors affecting the traditional dual-tip probes such as blinding, crawling, and drifting effects due to the interaction between the probe and bubbles can be prevented. The coherent signals reflected from both the front and rear ends of a bubble can provide velocity information. Deceleration of rising bubbles and particles due to the presence of the fiber probe is observed when they are very close to the fiber tip. With the residence time obtained, the bubble chord length can be determined by analyzing the coherent signal for velocity determination before the deceleration starts. The bubble diameters are directly obtained from analyzing the signals of the bubbles that contain velocity information. The chord lengths of these bubbles measured by FOR represent the bubble diameters when the bubble shape is spherical or represent the minor axes when the bubble shape is ellipsoidal. The velocity and size of bubbles obtained from the FOR measurements are compared with those obtained simultaneously using a high speed camera.

  18. Neurology and international organizations.

    Science.gov (United States)

    Mateen, Farrah J

    2013-07-23

    A growing number of international stakeholders are engaged with neurologic diseases. This article provides a brief overview of important international stakeholders in the practice of neurology, including global disease-specific programs, United Nations agencies, governmental agencies with international influence, nongovernmental organizations, international professional organizations, large private donors, private-public partnerships, commercial interests, armed forces, and universities and colleges. The continued engagement of neurologists is essential for the growing number of international organizations that can and should incorporate neurologic disease into their global agendas.

  19. On the shape of giant soap bubbles

    NARCIS (Netherlands)

    Cohen, C.; Darbois Texier, B.; Reyssat, E.; Snoeijer, Jacobus Hendrikus; Quere, D.; Clanet, Christophe

    2017-01-01

    We study the effect of gravity on giant soap bubbles and show that it becomes dominant above the critical size ℓ=a2/e0ℓ=a2/e0, where e0e0 is the mean thickness of the soap film and a=γb/ρg−√a=γb/ρg is the capillary length ( γbγb stands for vapor–liquid surface tension, and ρρ stands for the liquid

  20. Congenital and inherited neurologic diseases in dogs and cats: Legislation and its effect on purchase in Italy

    Directory of Open Access Journals (Sweden)

    Annamaria Passantino

    2016-05-01

    Full Text Available Many of the congenital neurologic diseases can result in incapacity or death of the animal. Some of them, such as idiopathic epilepsy and hydrocephalus, exhibit breed or familial predisposition and a genetic basis was proved or suggested. Some diseases can be presumptively diagnosed after a detailed signalment (breed predisposition, history (e.g. family history because many of these defects have familial tendencies, and through physical exam; other diagnostic methods (radiography, computed tomography, magnetic resonance, electrophysiologic tests, etc. can provide supportive evidence for the congenital defect and help to confirm the diagnosis. Some cases can lead to civil law-suits when the lesions are congenital, but not easily recognizable, or when the lesions are hereditary but tend to became manifest only after some time (more than 12 months after the date of purchase, e.g., after the vice-free guarantee period has expired. Moreover, quite frequently an early diagnosis is not made because there are delays in consulting the veterinarian or the general practitioner veterinarian does not perceive subtle signs. This study was designed to focus on the medico-legal aspects concerning the buying and selling in Italy of dogs and cats affected by congenital and hereditary neurologic diseases that could constitute vice in these animals. While adequate provisions to regulate in detail the various aspects of pet sale have still to be drawn up by legislators, it may be helpful to involve breeders, by obliging them by contract to extend guarantees in the case of hereditary lesions, including neurologic diseases.

  1. The Housing Bubble Fact Sheet

    OpenAIRE

    Dean Baker

    2005-01-01

    This paper explains the basic facts about the current housing market. It lays out the evidence that the rise in housing prices constitutes a housing bubble - and explains what can be expected when it inevitably collapses.

  2. Magnetism. Blowing magnetic skyrmion bubbles.

    Science.gov (United States)

    Jiang, Wanjun; Upadhyaya, Pramey; Zhang, Wei; Yu, Guoqiang; Jungfleisch, M Benjamin; Fradin, Frank Y; Pearson, John E; Tserkovnyak, Yaroslav; Wang, Kang L; Heinonen, Olle; te Velthuis, Suzanne G E; Hoffmann, Axel

    2015-07-17

    The formation of soap bubbles from thin films is accompanied by topological transitions. Here we show how a magnetic topological structure, a skyrmion bubble, can be generated in a solid-state system in a similar manner. Using an inhomogeneous in-plane current in a system with broken inversion symmetry, we experimentally "blow" magnetic skyrmion bubbles from a geometrical constriction. The presence of a spatially divergent spin-orbit torque gives rise to instabilities of the magnetic domain structures that are reminiscent of Rayleigh-Plateau instabilities in fluid flows. We determine a phase diagram for skyrmion formation and reveal the efficient manipulation of these dynamically created skyrmions, including depinning and motion. The demonstrated current-driven transformation from stripe domains to magnetic skyrmion bubbles could lead to progress in skyrmion-based spintronics. Copyright © 2015, American Association for the Advancement of Science.

  3. Microstreaming from Sessile Semicylindrical Bubbles

    Science.gov (United States)

    Hilgenfeldt, Sascha; Rallabandi, Bhargav; Guo, Lin; Wang, Cheng

    2014-03-01

    Powerful steady streaming flows result from the ultrasonic driving of microbubbles, in particular when these bubbles have semicylindrical cross section and are positioned in contact with a microfluidic channel wall. We have used this streaming in experiment to develop novel methods for trapping and sorting of microparticles by size, as well as for micromixing. Theoretically, we arrive at an analytical description of the streaming flow field through an asymptotic computation that, for the first time, reconciles the boundary layers around the bubble and along the substrate wall, and also takes into account the oscillation modes of the bubble. This approach gives insight into changes in the streaming pattern with bubble size and driving frequency, including a reversal of the flow direction at high frequencies with potentially useful applications. Present address: Mechanical and Aerospace Engineering, Missouri S &T.

  4. Neurological abnormalities predict disability

    DEFF Research Database (Denmark)

    Poggesi, Anna; Gouw, Alida; van der Flier, Wiesje

    2014-01-01

    To investigate the role of neurological abnormalities and magnetic resonance imaging (MRI) lesions in predicting global functional decline in a cohort of initially independent-living elderly subjects. The Leukoaraiosis And DISability (LADIS) Study, involving 11 European centres, was primarily aimed...... at evaluating age-related white matter changes (ARWMC) as an independent predictor of the transition to disability (according to Instrumental Activities of Daily Living scale) or death in independent elderly subjects that were followed up for 3 years. At baseline, a standardized neurological examination.......0 years, 45 % males), 327 (51.7 %) presented at the initial visit with ≥1 neurological abnormality and 242 (38 %) reached the main study outcome. Cox regression analyses, adjusting for MRI features and other determinants of functional decline, showed that the baseline presence of any neurological...

  5. Doughnut-shaped soap bubbles.

    Science.gov (United States)

    Préve, Deison; Saa, Alberto

    2015-10-01

    Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L. It is well known that the sphere is the solution for V=L(3)/6π(2), and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for Vbubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V<αL(3)/6π(2) cannot be stable and should not exist in foams, for instance.

  6. From rational bubbles to crashes

    Science.gov (United States)

    Sornette, D.; Malevergne, Y.

    2001-10-01

    We study and generalize in various ways the model of rational expectation (RE) bubbles introduced by Blanchard and Watson in the economic literature. Bubbles are argued to be the equivalent of Goldstone modes of the fundamental rational pricing equation, associated with the symmetry-breaking introduced by non-vanishing dividends. Generalizing bubbles in terms of multiplicative stochastic maps, we summarize the result of Lux and Sornette that the no-arbitrage condition imposes that the tail of the return distribution is hyperbolic with an exponent μbubble model to arbitrary dimensions d: a number d of market time series are made linearly interdependent via d× d stochastic coupling coefficients. We derive the no-arbitrage condition in this context and, with the renewal theory for products of random matrices applied to stochastic recurrence equations, we extend the theorem of Lux and Sornette to demonstrate that the tails of the unconditional distributions associated with such d-dimensional bubble processes follow power laws, with the same asymptotic tail exponent μmodel and the non-stationary growth rate model) of the RE bubble model that provide two ways of reconciliation with the stylized facts of financial data.

  7. Neurological diseases and pain

    OpenAIRE

    Borsook, David

    2011-01-01

    Chronic pain is a frequent component of many neurological disorders, affecting 20–40% of patients for many primary neurological diseases. These diseases result from a wide range of pathophysiologies including traumatic injury to the central nervous system, neurodegeneration and neuroinflammation, and exploring the aetiology of pain in these disorders is an opportunity to achieve new insight into pain processing. Whether pain originates in the central or peripheral nervous system, it frequentl...

  8. Probing the interaction between air bubble and sphalerite mineral surface using atomic force microscope.

    Science.gov (United States)

    Xie, Lei; Shi, Chen; Wang, Jingyi; Huang, Jun; Lu, Qiuyi; Liu, Qingxia; Zeng, Hongbo

    2015-03-03

    The interaction between air bubbles and solid surfaces plays important roles in many engineering processes, such as mineral froth flotation. In this work, an atomic force microscope (AFM) bubble probe technique was employed, for the first time, to directly measure the interaction forces between an air bubble and sphalerite mineral surfaces of different hydrophobicity (i.e., sphalerite before/after conditioning treatment) under various hydrodynamic conditions. The direct force measurements demonstrate the critical role of the hydrodynamic force and surface forces in bubble-mineral interaction and attachment, which agree well with the theoretical calculations based on Reynolds lubrication theory and augmented Young-Laplace equation by including the effect of disjoining pressure. The hydrophobic disjoining pressure was found to be stronger for the bubble-water-conditioned sphalerite interaction with a larger hydrophobic decay length, which enables the bubble attachment on conditioned sphalerite at relatively higher bubble approaching velocities than that of unconditioned sphalerite. Increasing the salt concentration (i.e., NaCl, CaCl2) leads to weakened electrical double layer force and thereby facilitates the bubble-mineral attachment, which follows the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory by including the effects of hydrophobic interaction. The results provide insights into the basic understanding of the interaction mechanism between bubbles and minerals at nanoscale in froth flotation processes, and the methodology on probing the interaction forces of air bubble and sphalerite surfaces in this work can be extended to many other mineral and particle systems.

  9. Single-bubble dynamics in pool boiling of one-component fluids

    KAUST Repository

    Xu, Xinpeng

    2014-06-04

    We numerically investigate the pool boiling of one-component fluids with a focus on the effects of surface wettability on the single-bubble dynamics. We employed the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)], a diffuse-interface model for liquid-vapor flows involving liquid-vapor transition in nonuniform temperature fields. We first perform simulations for bubbles on homogeneous surfaces. We find that an increase in either the contact angle or the surface superheating can enhance the bubble spreading over the heating surface and increase the bubble departure diameter as well and therefore facilitate the transition into film boiling. We then examine the dynamics of bubbles on patterned surfaces, which incorporate the advantages of both hydrophobic and hydrophilic surfaces. The central hydrophobic region increases the thermodynamic probability of bubble nucleation while the surrounding hydrophilic region hinders the continuous bubble spreading by pinning the contact line at the hydrophobic-hydrophilic intersection. This leads to a small bubble departure diameter and therefore prevents the transition from nucleate boiling into film boiling. With the bubble nucleation probability increased and the bubble departure facilitated, the efficiency of heat transfer on such patterned surfaces is highly enhanced, as observed experimentally [Int. J. Heat Mass Transfer 57, 733 (2013)]. In addition, the stick-slip motion of contact line on patterned surfaces is demonstrated in one-component fluids, with the effect weakened by surface superheating.

  10. Study on characteristics of single cavitation bubble considering condensation and evaporation of kerosene steam under ultrasonic vibration honing.

    Science.gov (United States)

    Ye, Linzheng; Zhu, Xijing; Wang, Lujie; Guo, Ce

    2018-01-01

    Ultrasonic vibration honing technology is an effective means for materials difficult to machine, where cavitation occurs in grinding fluid under the action of ultrasound. To investigate the changes of single cavitation bubble characteristics in the grinding area and how honing parameters influence bubble characteristics, a dynamic model of single cavitation bubble in the ultrasonic vibration honing grinding area was established. The model was based on the bubble dynamics and considered the condensation and evaporation of kerosene steam and honing processing environment. The change rules of bubble radius, temperature, pressure and number of kerosene steam molecules inside the bubble were numerically simulated in the process of bubble moving. The results show that the condensation and evaporation of kerosene steam can help to explain the changes of temperature and pressure inside the bubble. Compared with ultrasonic vibration, the amplitude of bubble radius is greatly suppressed in the ultrasonic honing environment. However, the rate of movement of the bubble is faster. Meanwhile, the minimum values of pressure and temperature are larger, and the number of kerosene steam molecules is less. By studying the effect of honing factors on the movement of the cavitation bubble, it is found that honing pressure has a greater influence on bubble evolution characteristics, while rotation speed of honing head has a minor effect and the reciprocating speed of honing head has little impacts. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Measuring online social bubbles

    Directory of Open Access Journals (Sweden)

    Dimitar Nikolov

    2015-12-01

    Full Text Available Social media have become a prevalent channel to access information, spread ideas, and influence opinions. However, it has been suggested that social and algorithmic filtering may cause exposure to less diverse points of view. Here we quantitatively measure this kind of social bias at the collective level by mining a massive datasets of web clicks. Our analysis shows that collectively, people access information from a significantly narrower spectrum of sources through social media and email, compared to a search baseline. The significance of this finding for individual exposure is revealed by investigating the relationship between the diversity of information sources experienced by users at both the collective and individual levels in two datasets where individual users can be analyzed—Twitter posts and search logs. There is a strong correlation between collective and individual diversity, supporting the notion that when we use social media we find ourselves inside “social bubbles.” Our results could lead to a deeper understanding of how technology biases our exposure to new information.

  12. Influence of surfactant on gas bubble stability.

    Science.gov (United States)

    Hanwright, Jennifer; Zhou, James; Evans, Geoffrey M; Galvin, Kevin P

    2005-05-24

    Gas-bubble stability is achieved either by a reduction in the Laplace pressure or by a reduction in the permeability of the gas-liquid interface. Although insoluble surfactants have been shown definitively in many studies to lower the permeability of the gas-liquid interface and hence increase the resistance to interfacial mass transfer, remarkably little work has been done on the effects of soluble surfactants. An experimental system was developed to measure the effect of the soluble surfactant dodecyl trimethylammonium bromide on the desorption and absorption of carbon dioxide gas through a quiescent planar interface. The desorption experiments conformed to the model of non-steady-state molecular diffusion. The absorption experiments, however, produced an unexpected mass transfer mechanism, with surface renewal, probably because of instability in the density gradient formed by the carbon dioxide. In general, the soluble surfactant produced no measurable reduction in the rate of interfacial mass transfer for desorption or absorption. This finding is consistent with the conclusion of Caskey and Barlage that soluble surfactants produce a significantly lower resistance to interfacial mass transfer than do insoluble surfactants. The dynamic adsorption and desorption of the surfactant molecules at the gas-liquid interface creates short-term vacancies, which presumably permit the unrestricted transfer of the gas molecules through the interface. This surfactant exchange does not occur for insoluble surfactants. Gas bubbles formed in the presence of a high concentration of soluble surfactant were observed to dissolve completely, while those formed in the presence of the insoluble surfactant stearic acid did not dissolve easily, and persisted for very long periods. The interfacial concentration of stearic acid rises during bubble dissolution, as it is insoluble, and must eventually achieve full monolayer coverage and a state of compression, lowering the permeability of the

  13. Numerical Analysis of the Influence of Low Frequency Vibration on Bubble Growth.

    Science.gov (United States)

    Han, D; Kedzierski, Mark A

    2017-01-01

    Numerical simulation of bubble growth during pool boiling under the influence of low frequency vibration was performed to understand the influence of common vibrations such as those induced by wind, highway transportation, and nearby mechanical devices on the performance of thermal systems that rely on boiling. The simulations were done for saturated R123 boiling at 277.6 K with a 15 K wall superheat. The numerical volume-of-fluid method (fixed grid) was used to define the liquid-vapor interface. The basic bubble growth characteristics including the bubble departure diameter and the bubble departure time were determined as a function of the bubble contact angle (20°-80°), the vibration displacement (10 µm-50 µm), the vibration frequency (5 Hz-25 Hz), and the initial vibration direction (positive or negative). The bubble parameters were shown to be strongly dependent on the bubble contact angle at the surface. For example, both the bubble departure diameter and the bubble departure time increased with the contact angle. At the same vibration frequency and the initial vibration direction, the bubble departure diameter and the bubble departure time both decreased with increasing vibration displacement. In addition, the vibration frequency had a greater effect on the bubble growth characteristics than did the vibration displacement. The vibration frequency effect was strongly influenced by the initial vibration direction. The pressure contour, the volume fraction of vapor phase, the temperature profile, and the velocity vector were investigated to understand these dynamic bubble behaviors. The limitation of the computational fluid dynamics approach was also described.

  14. The roles of particles in multiphase processes: Particles on bubble surfaces.

    Science.gov (United States)

    Bournival, Ghislain; Ata, Seher; Wanless, Erica J

    2015-11-01

    Particle-stabilised foams (or froths) form the fundamental framework of industrial processes like froth flotation. This review provides an overview of the effects of particles on bubble surfaces. The characteristics of the particles have a profound effect on the stability of the bubbles although the stabilisation mechanisms may differ. It is well known that layers of particles may provide a steric barrier between two interfaces, which prevents the coalescence of bubbles. Although perhaps considered of lesser importance, it is interesting to note that particles may affect the bubble surface and momentarily suppress coalescence despite being absent from the film separating two bubbles. Foams are at best metastable and coalescence occurs to achieve a state of minimum energy. Despite this, particles have been reported to stabilise bubbles for significant periods of time. Bubble coalescence is accompanied by a release of energy triggered by the sudden change in surface area. This produces a distinctive oscillation of the bubble surface, which may be influenced by the presence of incompressible particles yielding unique surface properties. A survey of the literature shows that the properties of these composite materials are greatly affected by the physicochemical characteristics of the particles such as hydrophobicity and size. The intense energy released during the coalescence of bubbles may be sufficient to expel particles from the bubble surface. It is noted that the detachment of particles may preferentially occur from specific locations on the bubble surface. Examination of the research accounts again reveals that the properties of the particles may affect their detachment upon the oscillation of the bubble surface. However, it is believed that most parameters affecting the detachment of particles are in fact modifying the dynamics of the three-phase line of contact. Both the oscillation of a coalescing bubble and the resulting detachment of particles are highly

  15. FEASTING BLACK HOLE BLOWS BUBBLES

    Science.gov (United States)

    2002-01-01

    A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth. These NASA Hubble Space Telescope images of the galaxy's central region clearly show one of the bubbles rising from a dark band of dust. The other bubble, emanating from below the dust band, is barely visible, appearing as dim red blobs in the close-up picture of the galaxy's hub (the colorful picture at right). The background image represents a wider view of the galaxy, with the central region defined by the white box. These extremely hot bubbles are caused by the black hole's voracious eating habits. The eating machine is engorging itself with a banquet of material swirling around it in an accretion disk (the white region below the bright bubble). Some of this material is spewed from the disk in opposite directions. Acting like high-powered garden hoses, these twin jets of matter sweep out material in their paths. The jets eventually slam into a wall of dense, slow-moving gas, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The bubbles will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this bubble-blowing phase is a short-lived event. The bubble is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of gas. The brighter bubble is 800 light-years tall and 800 light-years across. The observations are being presented June 5 at the American Astronomical Society meeting in Rochester, N.Y. Both pictures were taken March 24, 1999 with the Wide Field and Planetary Camera 2. False colors were used to enhance the details of the bubbles. The red regions in the picture denote the hot gas

  16. VOF simulation on a large bubble in a linear shear flow

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woo-Ram; Lee, Jae-Young [Handong Global University, Pohang (Korea, Republic of)

    2016-10-15

    Instability of flow around a body moving in a fluid can induce lift force acting on the body. One example of this phenomena is a bubble rising. Lift acting on a bubble effects on a void fraction distribution of a bubbly flow, which can be related to two phase flow in a nuclear reactor, bubble column reactor, and a flow around a ship. This leads researchers to use experimental or numerical methods. Study of Tomiyama et al.(2002) is the most well known experimental results on a bubble rising in a linear shear flow. They used water-glycerin mixture as a liquid and rotating belt to make linear shear flow, and measured lift coefficients. VOF simulations are conducted for investigation of lift acting on single bubble rising in a high Re linear shear flow. In spite of small amount of data and numerical error about spurious current near bubble interface, some insights can be obtained. First, a turbulence model generates large difference on C{sub L} of large Re bubble. Second, for lift acting on a large Re bubble in a linear shear flow, Re is better scale than E{sub oH} and C{sub L} is proportional to inverse of Re. Despite of some quantitative difference between results of experiment(Yang et al.(2013), Li et al.(2016)) and present numerical study, all results shows -7bubbles.

  17. Enhanced CHF with Bubble Cutter and Artificial Flow in Nuclear Plants

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chan Hee; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)

    2013-10-15

    The main goal of this paper is to body out the notions of forced convection system for enhanced local streams and air bubbles cutting (and/or pushing, breaking) system to explain how CHF can be improved and how those bubble cutter systems are applicable to NPPs. In this paper, the bubble cutter system and an artificial flow system which can cut (and/or push and break) air bubbles is bodied out to drag bubbles. It also make the surface wet condition of heated surfaces and improve heat transfer and prevent on creation of bubbles on the heated surfaces or heat exchangers or reactor cores. Namely, concepts and application methods to increase CHF are presented for NPPs. Enhanced critical heat flux (CHF) is one of our prospective aims for nuclear power plants (NPPs). Previous work has studied the flow boiling CHF enhancement with surfactant solutions under atmospheric pressure because surfactant solutions or surface conditions have an effect on the behavior of occurrence air bubbles on a heated surface. Another possible improvement is to improve efficiency of heat transfer or to body out some types of bubble breaking (and/or pushing, breaking) systems or an artificial flow of fluid that can tear off air bubbles or push hot liquid and bubbles on a surface of heater. During this study, it will be observed that those possible structures can elicit increased CHF by means of maintenance of contact with a coolant such as water.

  18. Superwettability of Gas Bubbles and Its Application: From Bioinspiration to Advanced Materials.

    Science.gov (United States)

    Yu, Cunming; Zhang, Peipei; Wang, Jingming; Jiang, Lei

    2017-09-13

    Gas bubbles in aqueous media are common and inevitable in, for example, agriculture and industrial processes. The behaviors of gas bubbles on solid interfaces, including generation, growth, coalescence, release, transport, and collection, are crucial to gas-bubble-related applications, which are always determined by gas-bubble wettability on solid interfaces. Here, the recent progress regarding the study of interfaces with gas-bubble superwettability in aqueous media, i.e., superaerophilicity and superaerophobicity, is summarized. Some examples illustrate how to design microstructures and chemical compositions to achieve reliable and effective manipulation of gas-bubble wettability on artificial interfaces. These designed interfaces exhibit excellent performance in gas-evolution reactions, gas-adsorption reactions, and directional gas-bubble transportation. Moreover, progress in the theoretical investigation of gas-bubble superwettability is reported. Lastly, some challenges are presented, such as the reliable manipulation of gas-bubble wettability and the establishment of mature theory for exactly and systematically explaining gas-bubble wetting phenomena. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Renal and Neurologic Effects of Cadmium, Lead, Mercury, and Arsenic in Children: Evidence of Early Effects and Multiple Interactions at Environmental Exposure Levels

    Science.gov (United States)

    de Burbure, Claire; Buchet, Jean-Pierre; Leroyer, Ariane; Nisse, Catherine; Haguenoer, Jean-Marie; Mutti, Antonio; Smerhovský, Zdenek; Cikrt, Miroslav; Trzcinka-Ochocka, Malgorzata; Razniewska, Grazyna; Jakubowski, Marek; Bernard, Alfred

    2006-01-01

    Lead, cadmium, mercury, and arsenic are common environmental pollutants in industrialized countries, but their combined impact on children’s health is little known. We studied their effects on two main targets, the renal and dopaminergic systems, in > 800 children during a cross-sectional European survey. Control and exposed children were recruited from those living around historical nonferrous smelters in France, the Czech Republic, and Poland. Children provided blood and urine samples for the determination of the metals and sensitive renal or neurologic biomarkers. Serum concentrations of creatinine, cystatin C, and β2-microglobulin were negatively correlated with blood lead levels (PbB), suggesting an early renal hyperfiltration that averaged 7% in the upper quartile of PbB levels (> 55 μg/L; mean, 78.4 μg/L). The urinary excretion of retinol-binding protein, Clara cell protein, and N-acetyl-β-d-glucosaminidase was associated mainly with cadmium levels in blood or urine and with urinary mercury. All four metals influenced the dopaminergic markers serum prolactin and urinary homovanillic acid, with complex interactions brought to light. Heavy metals polluting the environment can cause subtle effects on children’s renal and dopaminergic systems without clear evidence of a threshold, which reinforces the need to control and regulate potential sources of contamination by heavy metals. PMID:16581550

  20. Bubble merger and scaling law of the Rayleigh-Taylor instability with surface tension

    Science.gov (United States)

    Sohn, Sung-Ik; Baek, Seunghyeon

    2017-12-01

    We present a theoretical model to study the effects of surface tension on the growth of single and multiple bubbles in the Rayleigh-Taylor instability. The asymptotic solution for a single bubble is obtained and is expressed in terms of the Eötvös number. The bubble merger process is also demonstrated from the model. We find the contrasting effects of surface tension: it reduces the growth of a single bubble, but enhances the mixing rate of multiple bubbles at a late time. The bubble merger of Rayleigh-Taylor instability follows the same scaling law of the growth of mixing zone even when surface tension exists, but the growth coefficient in the scaling law increases with surface tension. A comparison with an experimental result is in good agreement.

  1. Deconvolution of acoustically detected bubble-collapse shock waves.

    Science.gov (United States)

    Johansen, Kristoffer; Song, Jae Hee; Johnston, Keith; Prentice, Paul

    2017-01-01

    The shock wave emitted by the collapse of a laser-induced bubble is detected at propagation distances of 30, 40and50mm, using a PVdF needle hydrophone, with a non-flat end-of-cable frequency response, calibrated for magnitude and phase, from 125kHz to 20MHz. High-speed shadowgraphic imaging at 5×106 frames per second, 10nstemporal resolution and 256 frames per sequence, records the bubble deflation from maximum to minimum radius, the collapse and shock wave generation, and the subsequent rebound in unprecedented detail, for a single sequence of an individual bubble. The Gilmore equation for bubble oscillation is solved according to the resolved bubble collapse, and simulated shock wave profiles deduced from the acoustic emissions, for comparison to the hydrophone recordings. The effects of single-frequency calibration, magnitude-only and full waveform deconvolution of the experimental data are presented, in both time and frequency domains. Magnitude-only deconvolution increases the peak pressure amplitude of the measured shock wave by approximately 9%, from single-frequency calibration, with full waveform deconvolution increasing it by a further 3%. Full waveform deconvolution generates a shock wave profile that is in agreement with the simulated profile, filtered according to the calibration bandwidth. Implications for the detection and monitoring of acoustic cavitation, where the role of periodic bubble collapse shock waves has recently been realised, are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. [Preliminary Research on Bubble Characteristics of Ancient Glaze Using OCT Technology].

    Science.gov (United States)

    Yan, Xin; Dong, Jun-qing; Li, Qing-hui; Guo, Mu-sen; Bu, Gong; Hu, Yong-qing

    2015-08-01

    The bubble is one of the most common feature in ancient glaze. The size and distribution of bubbles are closely associated with recipes of the raw materials for the body and glaze and the making process. To characterize the bubbles is essential for the study of ceramic production process, production places, times characteristics and so on. In order to explore the possibility of using the optical coherence tomography (OCT) imaging technology to characterize the bubbles and the bubble distribution characteristic in glaze of ancient porcelain, sweep frequency OCT imaging system is used to detect five different types ancient porcelain chips. According to the two dimensional sectional images and three dimensional tomographic images of the transparent layer of glaze obtained by the OCT imaging system, the two dimensional sectional images characteristics and three dimensional slices characteristics of the bubbles in glaze are studied. The bubble characteristics in the glaze and its possible causes that gases in the body of the ceramic overflow to the glaze layer in the firing process are comprehensively analyzed. Meantime, the size of bubble is calculated according to the two dimensional sectional images based on pixel, and the result is compared with the traditional microscopic test result. The bubble size, two dimensional sectional characteristics and three dimensional tomographic image characteristics of opaque glaze are also studied. Experimental results show that the bubble characteristics in glaze of different ancient porcelain chips are obvious difference, the result of the bubble size calculated based on pixel coincides with the result of the bubble size observed by traditional microscope with ten times magnification, slices of the body near the body-glaze binding region based on OCT imaging technology three dimensional tomography can effectively reflect the bubble characteristics in glaze. The measurement of using OCT imaging technology to characterize bubble

  3. Effects of the cyclooxygenase-2 inhibitor nimesulide on cerebral infarction and neurological deficits induced by permanent middle cerebral artery occlusion in the rat

    Directory of Open Access Journals (Sweden)

    Muñoz Eduardo

    2005-01-01

    Full Text Available Abstract Background Previous studies suggest that the cyclooxygenase-2 (COX-2 inhibitor nimesulide has a remarkable protective effect against different types of brain injury including ischemia. Since there are no reports on the effects of nimesulide on permanent ischemic stroke and because most cases of human stroke are caused by permanent occlusion of cerebral arteries, the present study was conducted to assess the neuroprotective efficacy of nimesulide on the cerebral infarction and neurological deficits induced by permanent middle cerebral artery occlusion (pMCAO in the rat. Methods Ischemia was induced by permanent occlusion of the middle cerebral artery in rats, via surgical insertion of a nylon filament into the internal carotid artery. Infarct volumes (cortical, subcortical and total and functional recovery, assessed by neurological score evaluation and rotarod performance test, were performed 24 h after pMCAO. In initial experiments, different doses of nimesulide (3, 6 and 12 mg/kg; i.p or vehicle were administered 30 min before pMCAO and again at 6, 12 and 18 h after stroke. In later experiments we investigated the therapeutic time window of protection of nimesulide by delaying its first administration 0.5–4 h after the ischemic insult. Results Repeated treatments with nimesulide dose-dependently reduced cortical, subcortical and total infarct volumes as well as the neurological deficits and motor impairment resulting from permanent ischemic stroke, but only the administration of the highest dose (12 mg/kg was able to significantly (P Conclusions These data show that nimesulide protects against permanent focal cerebral ischemia, even with a 2 h post-treatment delay. These findings have important implications for the therapeutic potential of using COX-2 inhibitors in the treatment of stroke.

  4. [Neurology and literature].

    Science.gov (United States)

    Iniesta, I

    2010-10-01

    Literature complements medical literature in the academic and clinical development of neurologists. The present article explores the contributions of writers of fiction on neurology. Literary works of fiction with particular reference to neurology. A symbiosis between writers of fiction and doctors has been well recognised. From Shakespeare to Cervantes by way of Dickens and Cela to writer - physicians such as Anton Chekhov or António Lobo Antunes have contributed through their medically informed literature to the better understanding of neurology. Some writers like Dostoevsky, Machado de Assis and Margiad Evans have written about their own experiences with disease thus bringing new insights to medicine. Furthermore, some neurological disorders have been largely based on literary descriptions. For instance, Dostoevsky's epilepsy has been retrospectively analysed by famous neurologists including Freud, Alajouanine or Gastaut, whilst his writings and biography have prompted others like Waxman and Geschwind to describe typical behavioural changes in temporal lobe epilepsy, finding their source of inspiration in Dostoevsky. Likewise, Cirignotta et al have named an unusual type of seizure after the Russian novelist. Inspired by Lewis Carroll, Todd introduced the term Alice in Wonderland Syndrome to refer to visual distortions generally associated with migraine. Writers of fiction offer a humanised perception of disease by contributing new insights into the clinical history, informing about the subjective experience of the illness and helping to eradicate the stigma associated to neurological disorders.

  5. Suicide in Neurologic Illness.

    Science.gov (United States)

    Arciniegas, David B.; Anderson, C. Alan

    2002-11-01

    The risk of attempted or completed suicide is increased in patients with migraine with aura, epilepsy, stroke, multiple sclerosis, traumatic brain injury, and Huntington's disease. Contrary to the general perception that the risk of suicide among patients with Alzheimer's disease and other dementing conditions is low, several reports suggest that the risk of suicide in these patients increases relative to the general population. Some patients at risk for neurologic disorders are also at increased risk for suicide; in particular, the risk of suicide is increased among persons at risk for Huntington's disease, independent of the presence or absence of the Huntington's gene mutation. The risk of attempted or completed suicide in neurologic illness is strongly associated with depression, feelings of hopelessness or helplessness, and social isolation. Additional suicide risk factors in persons with neurologic illness include cognitive impairment, relatively younger age (under 60 years), moderate physical disability, recent onset or change in illness, a lack of future plans or perceived meaning in life, recent losses (personal, occupational, or financial), and prior history of psychiatric illness or suicidal behavior. Substance dependence, psychotic disorders, anxiety disorders, and some personality disorders (eg, borderline personality disorder) may also contribute to increased risk of suicide among persons with neurologic illnesses. Identification and aggressive treatment of psychiatric problems, especially depression, as well as reduction of modifiable suicide risk factors among patients with neurologic illness is needed to reduce the risk of attempted and completed suicide in this population.

  6. Neurologic manifestations of achondroplasia.

    Science.gov (United States)

    Hecht, Jacqueline T; Bodensteiner, John B; Butler, Ian J

    2014-01-01

    Achondroplasia is the best described and most common form of the congenital short-limbed dwarfing conditions. Achondroplasia is apparent at birth and has a birth prevalence of 1 in 20000-30000 live-born infants. Achondroplasia is inherited as an autosomal dominant condition, although 80% of cases occur sporadically as new events in their families. Achondroplasia is caused, in virtually all of the cases, by a G380R mutation in fibroblast growth factor receptor 3 (FGFR3). Patients with achondroplasia should be evaluated by a multidisciplinary team of clinicians including geneticists, neurologists, and orthopedists, since there are numerous bony and neurological complications. The most severe complication results from craniocervical stenosis and medullary and upper spinal cord compression, which can have devastating and even lethal sequelae during early childhood. In subsequent decades, including adolescence, spinal cord and nerve compression are more prominent. The neurological complications of achondroplasia have been recognized in adults for more than a century and are attributed to bony defects, connective tissue structures, or both. Similar neurological complications are now appreciated in infants, young children, and teenagers with achondroplasia. Defective connective tissue elements in achondroplasia frequently lead to ligamentous laxity, which can aggravate the complications associated with bony stenosis. Bony abnormalities are known to cause neurological morbidity and lead to a shortened lifespan. Neurological complications associated with achondroplasia are reviewed, including recommendations for the evaluation and management of these clinical problems. © 2014 Elsevier B.V. All rights reserved.

  7. The self-imagination effect: benefits of a self-referential encoding strategy on cued recall in memory-impaired individuals with neurological damage.

    Science.gov (United States)

    Grilli, Matthew D; Glisky, Elizabeth L

    2011-09-01

    Knowledge of oneself is preserved in many memory-impaired individuals with neurological damage. Therefore, cognitive strategies that capitalize on mechanisms related to the self may be particularly effective at enhancing memory in this population. The present study investigated the effect of "self-imagining," imagining an event from a personal perspective, on short and long delayed cued recall in memory-impaired individuals with neurological damage. Sixteen patients intentionally encoded word pairs under four separate conditions: visual imagery, semantic elaboration, other person imagining, and self-imagining. The results revealed that self-imagining led to better performance than other-imagining, semantic elaboration, and visual imagery. Furthermore, the "self-imagination effect" (SIE) was preserved after a 30-min delay and was independent of memory functioning. These findings indicate that self-imagining provides a mnemonic advantage in brain-injured individuals, even those with relatively poor memory functioning, and suggest that self-imagining may tap into mnemonic mechanisms related to the self.

  8. Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

    Directory of Open Access Journals (Sweden)

    I. Leifer

    2017-06-01

    Full Text Available Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s−1 to derive the in situ calibration curve (Q(σ. These nonlinear curves related flux (Q to sonar return (σ for a multibeam echosounder (MBES and a single-beam echosounder (SBES for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering – precluding the use of a theoretical approach to derive Q(σ from the product of the bubble σ(r and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ(σ with respect to Q found Ψ(σ for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ(σ for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ(σ was bimodal for all but the weakest plumes. Q(σ was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes (Qm were 5.56, 42.73, and 4.88 mmol s−1 for MBES data with good to reasonable agreement (4–37 % between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ(Q was bimodal, with weak Ψ(Q in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.

  9. BUBBLE FORMATION EXPERIMENTS IN SNOW DENSIFICATION

    OpenAIRE

    イシイ, セイゴ; ナリタ, ヒデキ; マエノ, ノリカズ; Seigo, ISHII; Hideki, NARITA; Norikazu, MAENO

    1995-01-01

    Bubble formation experiments were conducted for snow composed of ice spheres 303μm in diameter at various temperatures and applied pressures. By measuring volumes of closed-off bubbles at various densities, the bubble formation density (ρ_f) and the bubble close-off density (ρ_c) were obtained. ρ_f, that is the density at which bubble formation begins, decreased with lowering temperature or pressure. On the other hand, ρ_c, that is the density at which bubble formation finishes, increased wit...

  10. Spherical Solutions of an Underwater Explosion Bubble

    Directory of Open Access Journals (Sweden)

    Andrew B. Wardlaw

    1998-01-01

    Full Text Available The evolution of the 1D explosion bubble flow field out to the first bubble minimum is examined in detail using four different models. The most detailed is based on the Euler equations and accounts for the internal bubble fluid motion, while the simplest links a potential water solution to a stationary, Isentropic bubble model. Comparison of the different models with experimental data provides insight into the influence of compressibility and internal bubble dynamics on the behavior of the explosion bubble.

  11. On the Inception of Financial Representative Bubbles

    Directory of Open Access Journals (Sweden)

    Massimiliano Ferrara

    2017-11-01

    Full Text Available In this work, we aim to formalize the inception of representative bubbles giving the condition under which they may arise. We will find that representative bubbles may start at any time, depending on the definition of a behavioral component. This result is at odds with the theory of classic rational bubbles, which are those models that rely on the fulfillment of the transversality condition by which a bubble in a financial asset can arise just at its first trade. This means that a classic rational bubble (differently from our model cannot follow a cycle since if a bubble exists, it will burst by definition and never arise again.

  12. Bubble rearrangements dynamics in foams

    Science.gov (United States)

    Le Merrer, Marie; Costa, Severine; Cohen-Addad, Sylvie; Hoehler, Reinhard

    2011-11-01

    Liquid foams are jammed dispersions of gas bubbles in a surfactant solution. Their structure evolves with time because surface tension drives a diffusive gas exchange between neighboring bubbles. This coarsening leads to a build-up of stresses which are relaxed upon local intermittent bubble rearrangements. These events govern the slow viscoelastic foam response, and similar bubble rearrangements are the elementary processes of plastic flow. Thus, the rearrangement duration is a key parameter describing how the microstructure dynamics control the macroscopic rheological response. We probe the duration of coarsening-induced rearrangements in 3D foams using a multiple light scattering technique (time resolved Diffusing-Wave Spectroscopy) as a function of the surfactant chemistry and the liquid fraction. As the foam becomes wetter, the confinement pressure of the packing goes to zero and the contacts between bubbles vanish. For mobile interfaces, we find that the rearrangements slow down as the jamming point is approached. These findings are compared to scaling laws which reveal an analogy between rearrangements dynamics in foams and granular suspensions.

  13. [Neurological sleep disorders].

    Science.gov (United States)

    Khatami, Ramin

    2014-11-01

    Neurological sleep disorders are common in the general population and may have a strong impact on quality of life. General practitioners play a key role in recognizing and managing sleep disorders in the general population. They should therefore be familiar with the most important neurological sleep disorders. This review provides a comprehensive overview of the most prevalent and important neurological sleep disorders, including Restless legs syndrome (with and without periodic limb movements in sleep), narcolepsy, NREM- and REM-sleep parasomnias and the complex relationship between sleep and epilepsies. Although narcolepsy is considered as a rare disease, recent discoveries in narcolepsy research provided insight in the function of brain circuitries involved in sleep wake regulation. REM sleep behavioral parasomnia (RBD) is increasingly recognized to represent an early manifestation of neurodegenerative disorders, in particular evolving synucleinopathies. Early diagnosis may thus open new perspectives for developing novel treatment options by targeting neuroprotective substances.

  14. The neurological disease ontology.

    Science.gov (United States)

    Jensen, Mark; Cox, Alexander P; Chaudhry, Naveed; Ng, Marcus; Sule, Donat; Duncan, William; Ray, Patrick; Weinstock-Guttman, Bianca; Smith, Barry; Ruttenberg, Alan; Szigeti, Kinga; Diehl, Alexander D

    2013-12-06

    We are developing the Neurological Disease Ontology (ND) to provide a framework to enable representation of aspects of neurological diseases that are relevant to their treatment and study. ND is a representational tool that addresses the need for unambiguous annotation, storage, and retrieval of data associated with the treatment and study of neurological diseases. ND is being developed in compliance with the Open Biomedical Ontology Foundry principles and builds upon the paradigm established by the Ontology for General Medical Science (OGMS) for the representation of entities in the domain of disease and medical practice. Initial applications of ND will include the annotation and analysis of large data sets and patient records for Alzheimer's disease, multiple sclerosis, and stroke. ND is implemented in OWL 2 and currently has more than 450 terms that refer to and describe various aspects of neurological diseases. ND directly imports the development version of OGMS, which uses BFO 2. Term development in ND has primarily extended the OGMS terms 'disease', 'diagnosis', 'disease course', and 'disorder'. We have imported and utilize over 700 classes from related ontology efforts including the Foundational Model of Anatomy, Ontology for Biomedical Investigations, and Protein Ontology. ND terms are annotated with ontology metadata such as a label (term name), term editors, textual definition, definition source, curation status, and alternative terms (synonyms). Many terms have logical definitions in addition to these annotations. Current development has focused on the establishment of the upper-level structure of the ND hierarchy, as well as on the representation of Alzheimer's disease, multiple sclerosis, and stroke. The ontology is available as a version-controlled file at http://code.google.com/p/neurological-disease-ontology along with a discussion list and an issue tracker. ND seeks to provide a formal foundation for the representation of clinical and research data

  15. Bubble Formation at a Submerged Orifice for Aluminum Foams Produced by Gas Injection Method

    Science.gov (United States)

    Fan, Xueliu; Chen, Xiang; Liu, Xingnan; Zhang, Huiming; Li, Yanxiang

    2013-02-01

    The bubble formation at a submerged orifice in the process of aluminum foams produced by gas injection method is investigated. The experimental results show that the increase of the gas flow rate and the orifice diameter can lead to increasing of the bubble size. The large orifice can make the frequency of bubble formation decrease by slowing down the increase of the gas chamber pressure when the gas flow rate increases. The effect of the gas chamber volume on the bubble size can be ignored in the experiment when it expands from 1 to 125 cm3. A theoretical model of bubble formation, expansion, and detachment under constant flow conditions is established to predict the bubble size. The theoretical predictions for air-aluminum melt systems are consistent with the experimental results.

  16. Thermal hydraulic test for reactor safety system; a visualization study on flow boiling and bubble behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Soon Heung; Baek, Won Pil; Ban, In Cheol [Korea Advanced Institute of Science and Technology, Taejeon (Korea)

    2002-03-01

    The project contribute to understand and to clarify the physical mechanism of flow nucleate boiling and CHF phenomena through the visualization experiments. the results are useful in the development of the enhancement device of heat transfer and to enhance nuclear fuel safety 1. Visual experimental facility 2. Application method of visualization Technique 3. Visualization results of flow nucleate boiling regime - Overall Bubble Behavior on the Heated Surface - Bubble Behavior near CHF Condition - Identification of Flow Structure - Three-layer flow structure 4. Quantifying of bubble parameter through a digital image processing - Image Processing Techniques - Classification of objects and measurements of the size - Three dimensional surface plot with using the luminance 5. Development and estimation of a correlation between bubble diameter and flow parameter - The effect of system parameter on bubble diameter - The development of a bubble diameter correlation . 49 refs., 42 figs., 7 tabs. (Author)

  17. The behavior of acoustic bubbles in aqueous solutions containing soluble polymers.

    Science.gov (United States)

    Tronson, Rohan; Tchea, Michelle F; Ashokkumar, Muthupandian; Grieser, Franz

    2012-11-26

    The effects of the water-soluble polymer polyvinylpyrrolidone (PVP) on the multibubble sonoluminescence (MBSL) intensity generated in aqueous solutions exposed to ultrasound at the two ultrasound frequencies of 20 and 363 kHz have been examined. In both cases, the presence of PVP, at concentrations of up to 2 g/100 mL, was found to enhance the MBSL intensity emitted from the solutions. On the basis of the intensity behavior of the SL observed from aqueous solutions containing PVP/surfactant and PVP/alcohol mixtures, it is suggested that PVP enhances MBSL by increasing the number of active bubbles in the system by hindering bubble-bubble coalescence processes and probably also by changing the structure of the bubble "clouds" formed at the acoustic antinodes in solution. The influence of PVP on bubble-bubble coalescence rates was also measured to support the interpretation of the MBSL emission experiments.

  18. Optical Observation Of A Collapsing Bubble Adhering To A Piezoelectric Transducer Surface Under Ultrasound Field

    Science.gov (United States)

    Yoshida, K.; Nakatani, S.; Watanabe, Y.

    The detailed behavior of a single bubble adhering to a solid surface was optically observed using an ultra-high-speed camera (1,000,000 frames/sec) in order to clarify the mechanical effect of micro-bubbles. The changing pressure between the bubble and the surface was simultaneously observed by a thin piezoelectric transducer on the surface. When the bubble collapsed, we confirmed the radiation of a micro-jet from the bubble, which was followed by a counter jet. An impulse positive pressure applied to the surface was also observed synchronously with the collapse. This pressure seems to come from the jet flow or the violent vibration of the bubble.

  19. Deformable ellipsoidal bubbles in Taylor-Couette flow with enhanced Euler-Lagrangian tracking

    Science.gov (United States)

    Spandan, Vamsi; Verzicco, Roberto; Lohse, Detlef

    2017-10-01

    In this work we present numerical simulations of 105 sub-Kolmogorov deformable bubbles dispersed in Taylor-Couette flow (a wall-bounded shear system) with rotating inner cylinder and outer cylinder at rest. We study the effect of deformability of the bubbles on the overall drag induced by the carrier fluid in the two-phase system. We find that an increase in deformability of the bubbles results in enhanced drag reduction due to a more pronounced accumulation of the deformed bubbles near the driving inner wall. This preferential accumulation is induced by an increase in the resistance to the motion of the bubbles in the wall-normal direction. The increased resistance is linked to the strong deformation of the bubbles near the wall which makes them prolate (stretched along one axis) and orient along the streamwise direction. A larger concentration of the bubbles near the driving wall implies that they are more effective in weakening the plume ejections which results in stronger drag reduction effects. These simulations which are practically impossible with fully resolved techniques are made possible by coupling a subgrid deformation model with two-way coupled Euler-Lagrangian tracking of sub-Kolmogorov bubbles dispersed in a turbulent flow field which is solved through direct numerical simulations. The bubbles are considered to be ellipsoidal in shape and their deformation is governed by an evolution equation which depends on the local flow conditions and their surface tension.

  20. Aspherical bubble dynamics and oscillation times

    Energy Technology Data Exchange (ETDEWEB)

    Godwin, R.P.; Chapyak, E.J. [Los Alamos National Lab., NM (United States); Noack, J.; Vogel, A. [Medizinisches Laserzentrum Luebeck (Germany)

    1999-03-01

    The cavitation bubbles common in laser medicine are rarely perfectly spherical and are often located near tissue boundaries, in vessels, etc., which introduce aspherical dynamics. Here, novel features of aspherical bubble dynamics are explored. Time-resolved experimental photographs and simulations of large aspect ratio (length:diameter {approximately}20) cylindrical bubble dynamics are presented. The experiments and calculations exhibit similar dynamics. A small high-pressure cylindrical bubble initially expands radially with hardly any axial motion. Then, after reaching its maximum volume, a cylindrical bubble collapses along its long axis with relatively little radial motion. The growth-collapse period of these very aspherical bubbles differs only sightly from twice the Rayleigh collapse time for a spherical bubble with an equivalent maximum volume. This fact justifies using the temporal interval between the acoustic signals emitted upon bubble creation and collapse to estimate the maximum bubble volume. As a result, hydrophone measurements can provide an estimate of the bubble energy even for aspherical bubbles. The prolongation of the oscillation period of bubbles near solid boundaries relative to that of isolated spherical bubbles is also discussed.

  1. Neurologic Diseases and Sleep.

    Science.gov (United States)

    Barone, Daniel A; Chokroverty, Sudansu

    2017-03-01

    Sleep disorders and neurologic illness are common and burdensome in their own right; when combined, they can have tremendous negative impact at an individual level as well as societally. The socioeconomic burden of sleep disorders and neurologic illness can be identified, but the real cost of these conditions lies far beyond the financial realm. There is an urgent need for comprehensive care and support systems to help with the burden of disease. Further research in improving patient outcomes in those who suffer with these conditions will help patients and their families, and society in general. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Neurologic Complications in Pregnancy.

    Science.gov (United States)

    Cuero, Mauricio Ruiz; Varelas, Panayiotis N

    2016-01-01

    Pregnant women are subject to the same complications as the general population, as well to specific neurologic complications associated with pregnancy, such as preeclampsia or eclampsia. The hormonal and physiologic changes during pregnancy lead to altered incidences of these complications, which usually present during the late period of pregnancy, labor, or the puerperium. In addition, the treatment of these conditions is different from that of nonpregnant women, because special attention is paid to avoid any abnormalities or death of the fetus. This article discusses the most common of these neurologic complications. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. The neurology literature 2016.

    Science.gov (United States)

    Khoujah, Danya; Chang, Wan-Tsu W; Abraham, Michael K

    2017-09-06

    Emergency neurology is a complex and rapidly changing field. Its evolution can be attributed in part to increased imaging options, debates about optimal treatment, and simply the growth of emergency medicine as a specialty. Every year, a number of articles published in emergency medicine or other specialty journals should become familiar to the emergency physician. This review summarizes neurology articles published in 2016, which the authors consider crucial to the practice of emergency medicine. The articles are categorized according to disease process, with the understanding that there can be significant overlap among articles. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Impact of baseline vitamin B12 status on the effect of vitamin B12 supplementation on neurologic function in older people: secondary analysis of data from the OPEN randomised controlled trial.

    Science.gov (United States)

    Miles, L M; Allen, E; Clarke, R; Mills, K; Uauy, R; Dangour, A D

    2017-10-01

    The available evidence from randomised controlled trials suggests that vitamin B12 supplementation does not improve neurologic function in older people with marginal but not deficient Vitamin B12 status. This secondary analysis used data from the Older People and Enhanced Neurological function (OPEN) randomised controlled trial to assess whether baseline vitamin B12 status or change in vitamin B12 status over 12 months altered the effectiveness of dietary vitamin B12 supplementation on neurologic function in asymptomatic older people with depleted vitamin B12 status at study entry. Vitamin B12 status was measured as serum concentrations of vitamin B12, holotranscobalamin, homocysteine and via a composite indicator (cB12). Neurological function outcomes included eleven electrophysiological measures of sensory and motor components of peripheral and central nerve function. Linear regression analyses were restricted to participants randomised into the intervention arm of the OPEN trial (n=91). Analyses revealed an inconsistent pattern of moderate associations between some measures of baseline vitamin B12 status and some neurological responses to supplementation. The directions of effect varied and heterogeneity in effect across outcomes could not be explained according to type of neurological outcome. There was no evidence of differences in the neurological response to vitamin B12 supplementation according to change from baseline over 12 months in any indicator of B12 status. This secondary analysis of high-quality data from the OPEN trial provides no evidence that baseline (or change from baseline) vitamin B12 status modifies the effect of vitamin B12 supplementation on peripheral or central nerve conduction among older people with marginal vitamin B12 status. There is currently insufficient evidence of efficacy for neurological function to support population-wide recommendations for vitamin B12 supplementation in healthy asymptomatic older people with marginal

  5. Rational Speculative Bubble Size in Gold, Hang Seng, S&P 500 and Nikkei 225 Index During Year 2008 to 2016

    Science.gov (United States)

    Borhan, Nurharyanti; Halim, Nurfadhlina Abdul; Amir, W. Ahmad Wan Muhammad

    2017-09-01

    A rational speculative bubble is a surge in asset prices that exceed its intrinsic value. Rational speculative bubbles are among the ascription which may lead to the collapse of an economic system. Rational speculative bubble cannot be created but it comes into existence when assets started to be traded. Financial rational speculative bubble and burst have negative effect on the economy and markets. Financial rational speculative bubbles are difficult to detect. This study aims to shows the size of rational speculative bubble in four markets, which are gold, Hang Seng, S&P500 and Nikkei 225 during year 2008 to 2016. In this study, generalized Johansen-Ledoit-Sornette model are used to find the size of the rational speculative bubble. Bubble detection is important for both sides of macro-economic decision makers and to the trader. Especially for a trading system that requires detailed knowledge about the time and the stage of the bubble burst.

  6. Morbidity and Mortality Patterns among Neurological Patients in the ...

    African Journals Online (AJOL)

    ANNALS

    Abstract. Background/Objective: The morbidity and mortality of neurological patients managed in the intensive care unit reflect the causes of neurological disorders and the effectiveness of management. Method: The morbidity and mortality patterns of neurological patients admitted into the intensive care unit of the University ...

  7. Undergraduate and Postgraduate Teaching of Neurology. Final Report.

    Science.gov (United States)

    Abrahamson, Stephen; Barrows, Howard S.

    This report describes a curriculum development project aimed at improving the teaching of neurology to undergraduate medical students; and providing more effective instruction in neurology for the practicing physician. The project involved: (1) development of a balanced presentation of neurological teaching from undergraduate medical education…

  8. The Analytical Hierarchy Process (Ahp) of Consumer Purchase Decision in Selecting Bubble Tea Shop

    OpenAIRE

    Pangkey, Violita Flamy; Lapian, S.L.H.V Joyce; Tumewu, Ferdinand

    2016-01-01

    Bubble tea also known as pearl milk tea is a popular Taiwanese tea-based drink invented in Taichung in the 1980s. Nowadays bubble tea shops are really popping up all over the world. Bubble tea shops have mushroomed all around Indonesia over the last few years. In Manado, there are at least three bubble tea brands that are very popular in town, those are Share Tea, Cha Time and Tea Presso. In today's era, the effect of the development of business has brought the business into a very tight comp...

  9. Kinetic energy and added mass of hydrodynamically interacting gas bubbles in liquid

    NARCIS (Netherlands)

    Kok, Jacobus B.W.

    1988-01-01

    By averaging the basic equations on microscale, expressions are derived for the effective added mass density and the kinetic energy density of a mixture of liquid and gas bubbles. Due to hydrodynamic interaction between the bubbles there appears to be a difference between the effective added mass

  10. Unorthodox bubbles when boiling in cold water

    Science.gov (United States)

    Parker, Scott; Granick, Steve

    2014-01-01

    High-speed movies are taken when bubbles grow at gold surfaces heated spotwise with a near-infrared laser beam heating water below the boiling point (60-70 °C) with heating powers spanning the range from very low to so high that water fails to rewet the surface after bubbles detach. Roughly half the bubbles are conventional: They grow symmetrically through evaporation until buoyancy lifts them away. Others have unorthodox shapes and appear to contribute disproportionately to heat transfer efficiency: mushroom cloud shapes, violently explosive bubbles, and cavitation events, probably stimulated by a combination of superheating, convection, turbulence, and surface dewetting during the initial bubble growth. Moreover, bubbles often follow one another in complex sequences, often beginning with an unorthodox bubble that stirs the water, followed by several conventional bubbles. This large dataset is analyzed and discussed with emphasis on how explosive phenomena such as cavitation induce discrepancies from classical expectations about boiling.

  11. Numerical Study of turbulent coherent structures and bubble entrainment under surfzone breaking waves

    Science.gov (United States)

    Ma, Gangfeng; Kirby, James; Shi, Fengyan

    2011-11-01

    Wave breaking in the surf zone entrains large volumes of bubbles into the water column. These bubbles are involved in intense interactions with mean flow and turbulence, producing a complex two phase bubbly flow field. It is necessary to describe the dynamics of breaking waves as two-phase flow with air bubbles of appropriate size distribution. The present study employ a three- dimensional large eddy simulation coupled with a two-phase bubbly flow model to investigate the detailed interactions between coherent structures and bubble entrainment in a laboratory scale breaking wave. Our results show that the vortical structures under the wave front are characterized by counter-rotating vortices. These vortices are initially carried downward by the downbursts, and then subject to stretching and bending to form obliquely descending eddies. To study the effects of coherent structures on turbulence and momentum transport, we conduct a TKE budget analysis. It is found that the TKE and Reynolds stress transport are closely related to obliquely descending eddies behind wave crest. Using the two-phase bubbly flow model, we are able to simulate the bubble entrainment and transport after wave breaking. Our results support the conclusion that the obliquely descending eddies have great effects on bubble entrainment and downward dispersion.

  12. Bubble induced flow field modulation for pool boiling enhancement over a tubular surface

    Science.gov (United States)

    Raghupathi, P. A.; Joshi, I. M.; Jaikumar, A.; Emery, T. S.; Kandlikar, S. G.

    2017-06-01

    We demonstrate the efficacy of using a strategically placed enhancement feature to modify the trajectory of bubbles nucleating on a horizontal tubular surface to increase both the critical heat flux (CHF) and the heat transfer coefficient (HTC). The CHF on a plain tube is shown to be triggered by a local dryout at the bottom of the tube due to vapor agglomeration. To mitigate this effect and delay CHF, the nucleating bubble trajectory is modified by incorporating a bubble diverter placed axially at the bottom of the tube. The nucleating bubble at the base of the diverter experiences a tangential evaporation momentum force (EMF) which causes the bubble to grow sideways away from the tube and avoid localized bubble patches that are responsible for CHF initiation. High speed imaging confirmed the lateral displacement of the bubbles away from the diverter closely matched with the theoretical predictions using EMF and buoyancy forces. Since the EMF is stronger at higher heat fluxes, bubble displacement increases with heat flux and results in the formation of separate liquid-vapor pathways wherein the liquid enters almost unobstructed at the bottom and the vapor bubble leaves sideways. Experimental results yielded CHF and HTC enhancements of ˜60% and ˜75%, respectively, with the diverter configuration when compared to a plain tube. This work can be used for guidance in developing enhancement strategies to effectively modulate the liquid-vapor flow around the heater surface at various locations to enhance HTC and CHF.

  13. Neurological aspects of eclampsia

    Directory of Open Access Journals (Sweden)

    Jovanović Dejana

    2003-01-01

    Full Text Available The difficult types of preeclampsia and eclampsia are presented with the neurological symptoms. The break of cerebral autoregulation mechanism plays the most important role in pathogenesis of cerebral vasospasm. Nevertheless eclampsia isn’t just an ordinary hypertensive encephalopathy because other pathogenic mechanisms are involved in its appearance. The main neuropathologic changes are multifocal vasogenic edema, perivascular multiple microinfarctions and petechial hemorrhages. Neurological clinical manifestations are convulsions, headache, visual disturbances and rarely other discrete focal neurological symptoms. Eclampsia is a high-risk factor for onset of hemorrhagic or ischemic stroke. This is a reason why neurological diagnostic tests are sometimes needed. The method of choice for evaluation of complicated eclampsia is computerized brain topography that shows multiple areas of hypodensity in occipitoparietal regions. These changes are focal vasogenic cerebral edema. For differential diagnosis of eclampsia and stroke other diagnostic methods can be used - fundoscopic exam, magnetic resonance brain imaging, cerebral angiography and cerebrospinal fluid exam. The therapy of eclampsia considers using of magnesium sulfate, antihypertensive, anticonvulsive and antiedematous drugs.

  14. Wikipedia and neurological disorders

    NARCIS (Netherlands)

    Brigo, Francesco; Igwe, Stanley C.; Nardone, Raffaele; Lochner, Piergiorgio; Tezzon, Frediano; Otte, WM

    2015-01-01

    Our aim was to evaluate Wikipedia page visits in relation to the most common neurological disorders by determining which factors are related to peaks in Wikipedia searches for these conditions. Millions of people worldwide use the internet daily as a source of health information. Wikipedia is a

  15. Astroglia in neurological diseases

    Czech Academy of Sciences Publication Activity Database

    Verkhratsky, Alexei; Rodríguez Arellano, Jose Julio; Parpura, V.

    2013-01-01

    Roč. 8, č. 2 (2013), s. 149-158 ISSN 1479-6708 R&D Projects: GA ČR(CZ) GAP304/11/0184; GA ČR GA309/09/1696 Institutional support: RVO:68378041 Keywords : amyotrophic lateral sclerosis * Alzheimer's disease * Alexander disease Subject RIV: FH - Neurology

  16. Effect of TiO2 Addition on Grain Growth, Anodic Bubble Evolution and Anodic Overvoltage of NiFe2O4-Based Composite Inert Anodes

    Science.gov (United States)

    Wang, Bin; Du, Jinjing; Liu, Yihan; Fang, Zhao; Hu, Ping

    2017-11-01

    A two-step powder compaction and sintering process was employed to fabricate TiO2-doped NiFe2O4 ceramic-based inert anodes. Grain growth during isothermal sintering was analyzed using Brook grain growth model. The bubble behavior of NiFe2O4 ceramic-based inert anodes was investigated in a two-compartment see-through quartz cell for aluminum electrolysis process. Anodic overvoltage and potential decay curves of the inert anodes were measured by using the steady state and current interruption technique. The results showed that the kinetic index of grain growth decreased with an increase in temperature. The average activation energy of grain growth for 1.0 wt.% TiO2-doped NiFe2O4 ceramic samples with a sintering temperature range from 1373 to 1673 K dropped from 675.30 to 183.47 kJ/mol. The diameter size of bubbles before releasing from the bottom surface of the anodes was reduced with increasing the current density, and the larger average releasing bubble size for carbon anode at the same current density could be obtained, which was compared to the NiFe2O4 inert anodes. Besides, the cell voltage of carbon anodes fluctuated much more violently under the same experimental conditions. After adding small amount of TiO2, a minor reduction in anodic overvoltage of NiFe2O4-based anodes can be observed.

  17. Effects of He irradiation on Ti{sub 3}AlC{sub 2}: Damage evolution and behavior of He bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chenxu; Yang, Tengfei; Kong, Shuyan; Xiao, Jingren; Xue, Jianming [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing (China); Wang, Qian; Hu, Chunfeng; Huang, Qing [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo (China); Wang, Yugang, E-mail: ygwang@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing (China)

    2013-09-15

    In present investigation, Ti{sub 3}AlC{sub 2} ceramic was irradiated at room temperature using 50 keV He ions with doses ranging from 8 × 10{sup 16} cm{sup −2} to 1 × 10{sup 18} cm{sup −2} and the corresponding peak values of dpa varying from 4 to 52. The damage evolution of nanolaminated crystalline structure as well as the formation and the growth of He bubbles induced by He irradiation were investigated by grazing incidence X-ray diffraction (GIXRD), atomic force microscope (AFM) and transmission electron microscopy (TEM). GIXRD analysis showed serious structural disorder but no obvious amorphization even at the highest dose, which was consistent with the selected area electron diffraction (SAED) results. AFM results demonstrated that serious blistering and exfoliation appeared on the surfaces at high doses. TEM observations revealed the formation of spherical He bubbles, string-like bubbles and “faulting zones” at various doses respectively.

  18. Bubble nucleation in an explosive micro-bubble actuator

    NARCIS (Netherlands)

    van den Broek, D.M.; Elwenspoek, Michael Curt

    2008-01-01

    Explosive evaporation occurs when a thin layer of liquid reaches a temperature close to the critical temperature in a very short time. At these temperatures spontaneous nucleation takes place. The nucleated bubbles instantly coalesce forming a vapour film followed by rapid growth due to the pressure

  19. Standardized patient outcomes trial (SPOT in neurology

    Directory of Open Access Journals (Sweden)

    Joseph E. Safdieh

    2011-01-01

    Full Text Available Background: The neurologic examination is a challenging component of the physical examination for medical students. In response, primarily based on expert consensus, medical schools have supplemented their curricula with standardized patient (SP sessions that are focused on the neurologic examination. Hypothesis-driven quantitative data are needed to justify the further use of this resource-intensive educational modality, specifically regarding whether using SPs to teach the neurological examination effects a long-term benefit on the application of neurological examination skills. Methods: This study is a cross-sectional analysis of prospectively collected data from medical students at Weill Cornell Medical College. The control group (n=129 received the standard curriculum. The intervention group (n=58 received the standard curriculum and an additional SP session focused on the neurologic examination during the second year of medical school. Student performance on the neurologic examination was assessed in the control and intervention groups via an OSCE administered during the fourth year of medical school. A Neurologic Physical Exam (NPE score of 0.0 to 6.0 was calculated for each student based on a neurologic examination checklist completed by the SPs during the OSCE. Composite NPE scores in the control and intervention groups were compared with the unpaired t-test. Results: In the fourth year OSCE, composite NPE scores in the intervention group (3.5±1.1 were statistically significantly greater than those in the control group (2.2±1.1 (p<0.0001. Conclusions: SP sessions are an effective tool for teaching the neurologic examination. We determined that a single, structured SP session conducted as an adjunct to our traditional lectures and small groups is associated with a statistically significant improvement in student performance measured 2 years after the session.

  20. Modeling and simulation of bubbles and particles

    Science.gov (United States)

    Dorgan, Andrew James

    The interaction of particles, drops, and bubbles with a fluid (gas or liquid) is important in a number of engineering problems. The present works seeks to extend the understanding of these interactions through numerical simulation. To model many of these relevant flows, it is often important to consider finite Reynolds number effects on drag, lift, torque and history force. Thus, the present work develops an equation of motion for spherical particles with a no-slip surface based on theoretical analysis, experimental data and surface-resolved simulations which is appropriate for dispersed multiphase flows. The equation of motion is then extended to account for finite particle size. This extension is critical for particles which will have a size significantly larger than the grid cell size, particularly important for bubbles and low-density particles. The extension to finite particle size is accomplished through spatial-averaging (both volume-based and surface-based) of the continuous flow properties. This averaging is consistent with the Faxen limit for solid spheres at small Reynolds numbers and added mass and fluid stress forces at inviscid limits. Further work is needed for more quantitative assessment of the truncation terms in complex flows. The new equation of motion is then used to assess the relative importance of each force in the context of two low-density particles (an air bubble and a sand particle) in a boundary layer of water. This relative importance is measured by considering effects on particle concentration, visualization of particle-fluid interactions, diffusion rates, and Lagrangian statistics collected along the particle trajectory. Strong added mass and stress gradient effects are observed for the bubble but these were found to have little effect on a sand particle of equal diameter. Lift was shown to be important for both conditions provided the terminal velocity was aligned with the flow direction. The influence of lift was found to be