Science.gov

Sample records for bubble trauma special

  1. Progression and severity of gas bubble trauma in juvenile salmonids

    USGS Publications Warehouse

    Mesa, M.G.; Weiland, L.K.; Maule, A.G.

    2000-01-01

    We conducted laboratory experiments to assess the progression and to quantify the severity of signs of gas bubble trauma (GBT) in juvenile chinook salmon Oncorhynchus tshawytscha and steelhead Oncorhynchus mykiss exposed to different levels of total dissolved gas (TDG), and we attempted to relate these signs to the likelihood of mortality. When fish were exposed to 110% TDG for up to 22 d, no fish died, and there were few signs of GBT in the lateral line or gills. Bubbles in the fins, however, were relatively common, and they progressively worsened over the experimental period. When fish were exposed to 120% TDG for up to 140 h, chinook salmon had an LT20 (time necessary to kill 20% of the fish) ranging from 40 to 120 h, whereas steelhead had LT20s ranging from 20 to 35 h. In steelhead, bubbles in the lateral line, fins, and gills displayed poor trends of worsening over time, showed substantial interindividual variability, and were poorly related to mortality. In chinook salmon, only bubbles in the lateral line showed a distinct worsening over time, and the severity of bubbles in the lateral line was highly correlated with mortality. When fish were exposed to 130% TDG for up to 11 h, LT20s for chinook salmon ranged from 3 to 6 h, whereas those for steelhead ranged from 5 to 7 h. In chinook salmon, bubbles in the lateral line and fins, but not those in the gills, showed distinct trends of worsening over time. In steelhead, bubbles in the lateral line displayed the most significant trend of progressive severity. In both species at 130% TDG, the severity of all GBT signs was highly correlated with mortality. The progressive nature of GBT and the methods we developed to examine fish for GBT may be useful for monitoring programs that aim to assess the severity of dissolved gas supersaturation exposures experienced by fish in the wild. However, the efficacy of such programs seems substantially hindered by problems associated with (1) the variable persistence of GBT signs

  2. Rate of disappearance of gas bubble trauma signs in juvenile salmonids

    USGS Publications Warehouse

    Hans, K.M.; Mesa, M.G.; Maule, A.G.

    1999-01-01

    To assess the rate of disappearance of gas bubble trauma (GBT) signs in juvenile salmonids, we exposed spring chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss to water containing high levels of dissolved gas supersaturation (DGS) for a time period sufficient to induce signs of GBT, reduced the DGS to minimal levels, and then sampled fish through time to document changes in severity of GBT. Because of the tendency of GBT signs to dissipate at different rates, we conducted trials focusing on emboli (bubbles) in the gill filaments and lateral line and separate trials that focused on bubbles in the external surfaces (fins, eyes, and opercula). Bubbles in gill filaments dissipated almost completely within 2 h after transfer of fish to water of nearly normal DGS (104%), whereas bubbles in the lateral line dissipated to negligible levels within 5 h. Bubbles on external surfaces were more persistent through time than they were in gill filaments and the lateral line. Although typically dissipating to low levels within 48 h, external bubbles sometimes remained for 4 d. Assuming a direct relation exists between easily observable signs and direct mortality, our results suggest that fish can recover quickly from the potentially lethal effects of DGS once they move from water with high DGS to water of almost normal gas saturation. These results should be of fundamental importance to fishery managers interpreting the results of monitoring for the severity and prevalence of GBT in juvenile salmonids in the Columbia River system and perhaps elsewhere.

  3. The trauma bubble: patient and family experience of serious burn injury.

    PubMed

    Gullick, Janice G; Taggart, Susan B; Johnston, Rae A; Ko, Natalie

    2014-01-01

    The aim of this study was to understand the lived experience of burn injury for Australian patients and families. Of specific interest was the period covering emergency and inhospital care and early experiences of transition into the community. Eighteen participants including patients with serious burn injury and close family members engaged in indepth, semistructured interviews. Data were analysed using Heideggerian phenomenology and were interpreted within the framework of Merleau-Ponty's philosophy of the body. Participants experienced substantial emotional trauma that was unrelated to burn size or severity. Emotional distress was highest amongst people with facial burns. Strong recollections of the accident and poorly managed pain seemed to exacerbate the experience of trauma. Patients described physical otherness, memories of consuming, embodied pain, and recycling of the initial catastrophe. Family members expressed vicarious suffering and were confronted by the physical otherness of their loved one. Participants were isolated in their "bubble of trauma" as they tried to contain grief and loss, and protect loved ones from their distress. Emotional trauma persisted after discharge challenging family functioning and adjustment. These findings support a systematic approach to identifying and responding to the emotional needs of patients and family, including early information about possible emotional reactions to traumatic events and proactive engagement with psychology services. Best practice approaches for early pain management should be a focus for both clinical care and further research.

  4. Gas Bubble Trauma Monitoring and Research of Juvenile Salmonids, 1994-1995 Progress Report.

    SciTech Connect

    Hans, Karen M.

    1997-07-01

    This report describes laboratory and field monitoring studies of gas bubble trauma (GBT) in migrating juvenile salmonids in the Snake and Columbia rivers. The first chapter describes laboratory studies of the progression of GBT signs leading to mortality and the use of the signs for GBT assessment. The progression and severity of GBT signs in juvenile salmonids exposed to different levels of total dissolved gas (TDG) and temperatures was assessed and quantified. Next, the prevalence, severity, and individual variation of GBT signs was evaluated to attempt to relate them to mortality. Finally, methods for gill examination in fish exposed to high TDG were developed and evaluated. Primary findings were: (1) no single sign of GBT was clearly correlated with mortality, but many GBT signs progressively worsened; (2) both prevalence and severity of GBT signs in several tissues is necessary; (3) bubbles in the lateral line were the earliest sign of GBT, showed progressive worsening, and had low individual variation but may develop poorly during chronic exposures; (4) fin bubbles had high prevalence, progressively worsened, and may be a persistent sign of GBT; and (5) gill bubbles appear to be the proximate cause of death but may only be relevant at high TDG levels and are difficult to examine. Chapter Two describes monitoring results of juvenile salmonids for signs of GBT. Emigrating fish were collected and examined for bubbles in fins and lateral lines. Preliminary findings were: (1) few fish had signs of GBT, but prevalence and severity appeared to increase as fish migrated downstream; (2) there was no apparent correlation between GBT signs in the fins, lateral line, or gills; (3) prevalence and severity of GBT was suggestive of long-term, non-lethal exposure to relatively low level gas supersaturated water; and (4) it appeared that GBT was not a threat to migrating juvenile salmonids. 24 refs., 26 figs., 3 tabs.

  5. Gas Bubble Trauma Monitoring in the Clearwater River Drainage, Idaho 1998.

    SciTech Connect

    Cochnauer, Tim

    1998-12-01

    Select portions of the Clearwater and North Fork of the Clearwater rivers were electroshocked to estimate the incidence of gas bubble trauma (GBT) occurring in resident fish populations for the spring and summer months of 1998. The study area was divided into four sections and sampled weekly during periods of spill and non-spill from Dworshak Dam. Five thousand five hundred and forty one fish, representing 22 different species, were captured and examined for GBT. Two fish were detected with signs of GBT; exhibiting the lowest incidence of GBT in the last four years (0.04%). Reduced discharge and lower levels of total dissolved gases may have resulted in lower incidence of GBT in the 1998 monitoring period.

  6. Bubbles

    NASA Astrophysics Data System (ADS)

    Prosperetti, Andrea

    2004-06-01

    Vanitas vanitatum et omnia vanitas: bubbles are emptiness, non-liquid, a tiny cloud shielding a mathematical singularity. Born from chance, a violent and brief life ending in the union with the (nearly) infinite. But a wealth of phenomena spring forth from this nothingness: underwater noise, sonoluminescence, boiling, and many others. Some recent results on a "blinking bubble" micropump and vapor bubbles in sound fields are outlined. The last section describes Leonardo da Vinci's observation of the non-rectlinear ascent of buoyant bubbles and justifies the name Leonardo's paradox recently attributed to this phenomenon.

  7. Lateral line pore diameters correlate with the development of gas bubble trauma signs in several Columbia River fishes

    USGS Publications Warehouse

    Morris, R.G.; Beeman, J.W.; VanderKooi, S.P.; Maule, A.G.

    2003-01-01

    Gas bubble trauma (GBT) caused by gas supersaturation of river water continues to be a problem in the Columbia River Basin. A common indicator of GBT is the percent of the lateral line occluded with gas bubbles; however, this effect has never been examined in relation to lateral line morphology. The effects of 115, 125 and 130% total dissolved gas levels were evaluated on five fish species common to the upper Columbia River. Trunk lateral line pore diameters differed significantly (P<0.0001) among species (longnose sucker>largescale sucker>northern pikeminnow???chinook salmon???redside shiner). At all supersaturation levels evaluated, percent of lateral line occlusion exhibited an inverse correlation to pore size but was not generally related to total dissolved gas level or time of exposure. This study suggests that the differences in lateral line pore diameters between species should be considered when using lateral line occlusion as an indicator of gas bubble trauma. ?? 2003 Elsevier Science Inc. All rights reserved.

  8. Trauma.

    PubMed

    Huisman, Thierry A G M; Poretti, Andrea

    2016-01-01

    Traumatic brain and spine injury (TBI/TSI) is a leading cause of death and lifelong disability in children. The biomechanical properties of the child's brain, skull, and spine, the size of the child, the age-specific activity pattern, and variance in trauma mechanisms result in a wide range of age-specific traumas and patterns of brain and spine injuries. A detailed knowledge about the various types of primary and secondary pediatric head and spine injuries is essential to better identify and understand pediatric TBI/TSI, which enhances sensitivity and specificity of diagnosis, will guide therapy, and may give important information about the prognosis. The purposes of this chapter are to: (1) discuss the unique epidemiology, mechanisms, and characteristics of TBI/TSI in children; (2) review the anatomic and functional imaging techniques that can be used to study common and rare pediatric TBI/TSI and their complications; (3) comprehensively review frequent primary and secondary brain injuries; and (4) to give a short overview of two special types of pediatric TBI/TSI: birth-related and nonaccidental injuries.

  9. Influence of infection with Renibacterium salmoninarum on susceptibility of juvenile spring chinook salmon to gas bubble trauma

    USGS Publications Warehouse

    Weiland, L.K.; Mesa, M.G.; Maule, A.G.

    1999-01-01

    During experiments in our laboratory to assess the progression and severity of gas bubble trauma (GBT) in juvenile spring chinook salmon Oncorhynchus tshawytscha, we had the opportunity to assess the influence of Renibacterium salmoninarum (Rs), the causative agent of bacterial kidney disease, on the susceptibility of salmon to GBT. We exposed fish with an established infection of Rs to 120% total dissolved gas (TDG) for 96 h and monitored severity of GBT signs in the fins and gills, Rs infection level in kidneys by using an enzyme-linked immunosorbent assay (ELISA), and mortality. Mortality occurred rapidly after exposure to 120% TDG, with a LT20 (time necessary to kill 20% of the population) of about 37 h, which is at a minimum about 16% earlier than other bioassays we have conducted using fish that had no apparent signs of disease. Fish that died early (from 31 to 36 h and from 49 to 52 h) had significantly higher infection levels (mean ?? SE ELISA absorbance = 1.532 ?? 0.108) than fish that survived for 96h (mean ?? SE ELISA absorbance = 0.828 ?? 0.137). Fish that died early also had a significantly greater number of gill filaments occluded with bubbles than those that survived 96 h. Conversely, fish that survived for 96 h had a significantly higher median fin severity ranking than those that died early. Our results indicate that fish with moderate to high levels of Rs infection are more vulnerable to the effects of dissolved gas supersaturation (DGS) and die sooner than fish with lower levels of Rs infection. However, there is a substantial amount of individual variation in susceptibility to the apparent cumulative effects of DGS and Rs infection. Collectively, our findings have important implications to programs designed to monitor the prevalence and severity of GBT in juvenile salmonids in areas like the Columbia River basin and perhaps elsewhere.

  10. Review of Current Literature and Research on Gas Supersaturation and Gas Bubble Trauma: Special Publication Number 1, 1986.

    SciTech Connect

    Colt, John; Bouck, Gerald R.; Fidler, Larry

    1986-12-01

    This report presents recently published information and on-going research on the various areas of gas supersaturation. Growing interest in the effects of chronic gas supersaturation on aquatic animals has been due primarily to heavy mortality of salmonid species under hatchery conditions. Extensive examination of affected animals has failed to consistently identify pathogenic organisms. Water quality sampling has shown that chronic levels of gas supersaturation are commonly present during a significant period of the year. Small marine fish larvae are significantly more sensitive to gas supersaturation than salmonids. Present water quality criteria for gas supersaturation are not adequate for the protection of either salmonids under chronic exposure or marine fish larvae, especially in aquaria or hatcheries. To increase communication between interested parties in the field of gas supersaturation research and control, addresses and telephone numbers of all people responding to the questionnaire are included. 102 refs.

  11. Specialized disaster behavioral health training: Its connection with response, practice, trauma health, and resilience

    PubMed Central

    Atkins, Christiana D.; Burnett,, Harvey J.

    2016-01-01

    Abstract This study examined the relationship between having training in key disaster behavioral health (DBH) interventions and trauma health (compassion fatigue, burnout and compassion satisfaction), resilience, the number of crisis responses participated in within the last year, and the frequency of assembling to practice crisis interventions skills. Data was collected from a convenience sample of disaster behavioral health responders (N = 139) attending a training conference in Michigan. Measures included the Professional Quality of Life Scale, the 14-item Resilience Scale, and a demographic questionnaire. Point biserial correlations revealed that having training in large and small group crisis interventions and individual and peer crisis interventions was significantly correlated with higher resilience and lower levels of burnout. Psychological First Aid was not significantly associated with any of the trauma health variables or with resilience. Compassion fatigue and compassion satisfaction were not significantly associated with DBH training. Chi-square tests for independence found no significant association between key DBH training strategies and the number of crisis responses participated in within the past year and the frequency of assembling to practice crisis interventions skills. These findings suggest that completing training in both, large and small group and individual and peer crisis intervention techniques may help to increase resiliency and reduce burnout among disaster behavioral health providers. PMID:28229015

  12. Vapor Bubbles

    NASA Astrophysics Data System (ADS)

    Prosperetti, Andrea

    2017-01-01

    This article reviews the fundamental physics of vapor bubbles in liquids. Work on bubble growth and condensation for stationary and translating bubbles is summarized and the differences with bubbles containing a permanent gas stressed. In particular, it is shown that the natural frequency of a vapor bubble is proportional not to the inverse radius, as for a gas bubble, but to the inverse radius raised to the power 2/3. Permanent gas dissolved in the liquid diffuses into the bubble with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous bubbly liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor bubbles in an immiscible liquid.

  13. An Inquiry of the Lived Experiences and Contextual Understandings of Early Childhood Special Educators Related to Children's Trauma

    ERIC Educational Resources Information Center

    DuBois, Alison L.

    2010-01-01

    Secondary trauma stress, compassion fatigue, and vicarious trauma are terms rarely found in educational literature. Studies have shown the significant and lasting ramifications of these constructs within the realm of counseling and psychology. Professionals working in educational settings with high risk populations encounter multiple exposures to…

  14. Bubble and bubble cloud dynamics

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yoichiro

    2000-07-01

    Cavitation bubbles are formed from small air bubbles, so-called nuclei, with the surrounding pressure reduction caused by the flow, and then, the bubbles shrink and collapse with the surrounding pressure rise. Such volumetric changes of bubbles are calculated in detail and it is found that they are significantly influenced by the internal phenomena, such as thermal diffusion, mist formation due to a homogeneous condensation, mass diffusion between vapor and noncondensable gas, heat and mass transfer through the bubble wall. The structure in cavitating flow interacts with the cavitation bubbles, and those bubbles form a cloud cavitation. It is well known that cloud cavitation is one of the most destructive forms. The behavior of bubble clouds is simulated numerically. An inward propagating shock wave is formed during the collapse of the bubble cloud, and the shock wave and its precursor are focused at the cloud center area. These phenomena associate high frequency pressure oscillations and violent bubble collapses. Those bubble collapses emit high pressure peaks, which are several hundreds times larger than that of a single bubble collapse.

  15. Bubble Combustion

    NASA Technical Reports Server (NTRS)

    Corrigan, Jackie

    2004-01-01

    A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM

  16. Sinking Bubbles

    NASA Astrophysics Data System (ADS)

    Koch, Jeremy; Ewoldt, Randy

    2016-11-01

    Intuition tells us that bubbles will rise and steel objects will sink in liquids, though here we describe the opposite. With experimental demonstration and theoretical rationale, we describe how the motion of containers of liquid with immersed solid objects and air bubbles can cause curious behaviors: sinking bubbles and rising high-density particles. Bubbles and solid spheres of diameter on the order of a few millimeters are introduced into fluids with different rheological constitutive behaviors. Imposed motion of the rigid container allows for control of the trajectories of the immersed particles - without the container imparting direct shearing motion on the fluid. Results demonstrate the necessary conditions to prevent or produce net motion of the bubbles and heavy particles, both with and against gravitational expectations.

  17. Bubble, Bubble, Toil and Trouble.

    ERIC Educational Resources Information Center

    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)

  18. Bubble diagnostics

    DOEpatents

    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.

  19. Trauma: the seductive hypothesis.

    PubMed

    Reisner, Steven

    2003-01-01

    In much of contemporary culture, "trauma" signifies not so much terrible experience as a particular context for understanding and responding to a terrible experience. In therapy, in the media, and in international interventions, the traumatized are seen not simply as people who suffer and so are deserving of concern and aid; they are seen also as people who suffer for us, who are given special dispensation. They are treated with awe if they tell a certain kind of trauma story, and are ignored or vilified if they tell another. Trauma has become not simply a story of pain and its treatment, but a host of sub-stories involving the commodification of altruism, the justification of violence and revenge, the entry point into "true experience," and the place where voyeurism and witnessing intersect. Trauma is today the stuff not only of suffering but of fantasy. Historically, trauma theory and treatment have shown a tension, exemplified in the writings of Freud and Janet, between those who view trauma as formative and those who view it as exceptional. The latter view, that trauma confers exceptional status deserving of special privilege, has gained ground in recent years and has helped to shape the way charitable dollars are distributed, how the traumatized are presented in the media, how governments justify and carry out international responses to trauma, and how therapists attend to their traumatized patients. This response to trauma reflects an underlying, unarticulated belief system derived from narcissism; indeed, trauma has increasingly become the venue, in society and in treatment, where narcissism is permitted to prevail.

  20. Primordial Bubbles within Primordial Bubbles

    NASA Astrophysics Data System (ADS)

    Occhionero, Franco; Amendola, Luca; Corasaniti, Pier Stefano

    The nucleation of primordial bubbles during an inflationary phase transition has been suggested to promote the formation of structure either above or below the horizon, depending on whether the nucleation occurs more or less than 60 e-folds before the end of inflation. Here we propose a mechanism which has both features and produces subhorizon cavities up to hundreds of h-1 Mpc -- where excess power is observed -- inside superhorizon bubbles, i.e. in open universes. For this purpose we build a new inflationary two-field model with two vacuum channels in the potential surface: by modulating the energy difference between these channels, episodes of back and forth transition occur in sequence during inflation. Thus, one physical process may i) reconcile inflation with openness and ii) seed a distribution of observable voids. Bubble spectra are given in terms of phenomenological parameters which in turn are functions of microscopic physical parameters. In principle large scale structure constrains fundamental physics: for example, to account for power at scales of hundreds of h-1 Mpc the singularity in the Euclidean action -- which separates the first from the second phase transition -- must be mild enough. The smoking gun of the process might be the imprint of non-Gaussian, ring-like signals on the microwave background at l > 1000 by the subhorizon bubbles. On the other end of the spectrum, the contribution to l =1,2 from the off-centerness of the observer in the open bubble, is being evaluated.

  1. Post-traumatic Vertical Gaze Paresis in Nine Patients: Special Vulnerability of the Artery of Percheron in Trauma?

    PubMed Central

    Galvez-Ruiz, Alberto

    2015-01-01

    Purpose: The purpose was to present a case series of vertical gaze paresis in patients with a history of cranioencephalic trauma (CET). Methods: The clinical characteristics and management are presented of nine patients with a history of CET secondary to motor vehicle accidents with associated vertical gaze paresis. Results: Neuroimaging studies indicated posttraumatic contusion of the thalamic-mesencephalic region in all nine patients who corresponded to the artery of Percheron region; four patients had signs of hemorrhagic transformation. Vertical gaze paresis was present in all patients, ranging from complete paralysis of the upward and downward gaze to a slight limitation of upward gaze. Discussion: Posttraumatic vertical gaze paresis is a rare phenomenon that can occur in isolation or in association with other neurological deficits and can cause a significant limitation in the quality-of-life. Studies in the literature have postulated that the unique anatomy of the angle of penetration of the thalamoperforating and lenticulostriate arteries makes these vessels more vulnerable to isolated selective damage in certain individuals and can cause-specific patterns of CET. PMID:26180479

  2. Leverage bubble

    NASA Astrophysics Data System (ADS)

    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.

  3. Tiny Bubbles.

    ERIC Educational Resources Information Center

    Kim, Hy

    1985-01-01

    A simple oxygen-collecting device (easily constructed from glass jars and a lid) can show bubbles released by water plants during photosynthesis. Suggestions are given for: (1) testing the collected gas; (2) using various carbon dioxide sources; and (3) measuring respiration. (DH)

  4. Bubble Drag Reduction Requires Large Bubbles

    NASA Astrophysics Data System (ADS)

    Verschoof, Ruben A.; van der Veen, Roeland C. A.; Sun, Chao; Lohse, Detlef

    2016-09-01

    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.

  5. Ear trauma.

    PubMed

    Eagles, Kylee; Fralich, Laura; Stevenson, J Herbert

    2013-04-01

    Understanding basic ear anatomy and function allows an examiner to quickly and accurately identify at-risk structures in patients with head and ear trauma. External ear trauma (ie, hematoma or laceration) should be promptly treated with appropriate injury-specific techniques. Tympanic membrane injuries have multiple mechanisms and can often be conservatively treated. Temporal bone fractures are a common cause of ear trauma and can be life threatening. Facial nerve injuries and hearing loss can occur in ear trauma.

  6. Systemic trauma.

    PubMed

    Goldsmith, Rachel E; Martin, Christina Gamache; Smith, Carly Parnitzke

    2014-01-01

    Substantial theoretical, empirical, and clinical work examines trauma as it relates to individual victims and perpetrators. As trauma professionals, it is necessary to acknowledge facets of institutions, cultures, and communities that contribute to trauma and subsequent outcomes. Systemic trauma-contextual features of environments and institutions that give rise to trauma, maintain it, and impact posttraumatic responses-provides a framework for considering the full range of traumatic phenomena. The current issue of the Journal of Trauma & Dissociation is composed of articles that incorporate systemic approaches to trauma. This perspective extends conceptualizations of trauma to consider the influence of environments such as schools and universities, churches and other religious institutions, the military, workplace settings, hospitals, jails, and prisons; agencies and systems such as police, foster care, immigration, federal assistance, disaster management, and the media; conflicts involving war, torture, terrorism, and refugees; dynamics of racism, sexism, discrimination, bullying, and homophobia; and issues pertaining to conceptualizations, measurement, methodology, teaching, and intervention. Although it may be challenging to expand psychological and psychiatric paradigms of trauma, a systemic trauma perspective is necessary on both scientific and ethical grounds. Furthermore, a systemic trauma perspective reflects current approaches in the fields of global health, nursing, social work, and human rights. Empirical investigations and intervention science informed by this paradigm have the potential to advance scientific inquiry, lower the incidence of a broader range of traumatic experiences, and help to alleviate personal and societal suffering.

  7. Interaction of Two Differently Sized Bubbles in a Free Field

    NASA Astrophysics Data System (ADS)

    Chew, Lup Wai; Khoo, Boo Cheong; Klaseboer, Evert; Ohl, Siew-Wan

    The interaction between two different sized (spark created, non-equilibrium) bubbles is studied by using high speed photography. The bubble size ranges from 2 to 7 mm. The experimental results are compared to that of the similar sized bubbles reported in the literature. Interestingly, all the four major behaviors of bubble-bubble interactions (i.e. 'bubble-collapsed' induced liquid jets directed away from each other, liquid jets directed towards each other, bubble coalescence and the 'catapult' effect) are observed which bear much similarity to that found for similar sized bubbles' interaction. The main parameters studied/varied are the size of the bubbles, the dimensionless separation distance and the phase difference between the two bubbles. The results obtained are consistent with the cases of similar sized bubbles reported in the literature, with each type of behavior occupying a distinct region in the graphical plot. This indicates that the results for the (special) similar sized bubbles can be generalized to cases with different sized bubbles. Many of the real life applications such as cavitations corrosions often involve bubbles with significant size difference, thus the present findings are useful in predicting the behavior of multiple bubbles in many situations.

  8. The role of the trauma nurse leader in a pediatric trauma center.

    PubMed

    Wurster, Lee Ann; Coffey, Carla; Haley, Kathy; Covert, Julia

    2009-01-01

    The trauma nurse leader role was developed by a group of trauma surgeons, hospital administrators, and emergency department and trauma leaders at Nationwide Children's Hospital who recognized the need for the development of a core group of nurses who provided expert trauma care. The intent was to provide an experienced group of nurses who could identify and resolve issues in the trauma room. Through increased education, exposure, mentoring, and professional development, the trauma nurse leader role has become an essential part of the specialized pediatric trauma care provided at Nationwide Children's Hospital.

  9. Bubbling orientifolds

    NASA Astrophysics Data System (ADS)

    Mukhi, Sunil; Smedbäck, Mikael

    2005-08-01

    We investigate a class of 1/2-BPS bubbling geometries associated to orientifolds of type-IIB string theory and thereby to excited states of the SO(N)/Sp(N) Script N = 4 supersymmetric Yang-Mills theory. The geometries are in correspondence with free fermions moving in a harmonic oscillator potential on the half-line. Branes wrapped on torsion cycles of these geometries are identified in the fermi fluid description. Besides being of intrinsic interest, these solutions may also occur as local geometries in flux compactifications where orientifold planes are present to ensure global charge cancellation. We comment on the extension of this procedure to M-theory orientifolds.

  10. Single Bubble Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Farley, Jennifer; Hough, Shane

    2003-05-01

    Single Bubble Sonoluminescence is the emission of light from a single bubble suspended in a liquid caused by a continuum of repeated implosions due to pressure waves generated from a maintained ultrasonic sinusoidal wave source. H. Frenzel and H. Schultz first studied it in 1934 at the University of Cologne. It was not until 1988 with D.F. Gaitan that actual research began with single bubble sonoluminescence. Currently many theories exist attempting to explain the observed bubble phenomenon. Many of these theories require spherical behavior of the bubble. Observation of the bubble has shown that the bubble does not behave spherically in most cases. One explanation for this is known as jet theory. A spectrum of the bubble will give us the mean physical properties of the bubble such as temperature and pressure inside the bubble. Eventually, with the aide of fluorocene dye a full spectrum of the bubble will be obtained.

  11. Childhood Trauma.

    ERIC Educational Resources Information Center

    Falasca, Tony; Caulfield, Thomas J.

    1999-01-01

    Describes some classic causes of trauma and symptoms that can result when a child has been traumatized. Lists several factors that effect the degree to which a child is affected by trauma. Categories a wide range of behaviors displayed by the victims into three groups: affect, memories, and behaviors. Discusses various considerations when…

  12. Acoustic bubble removal method

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)

    1983-01-01

    A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.

  13. [Facial trauma and multiple trauma].

    PubMed

    Corre, Pierre; Arzul, Ludovic; Khonsari, Roman Hossein; Mercier, Jacques

    2013-09-01

    The human face contains the sense organs and is responsible for essential functions: swallowing, chewing, speech, breathing and communication. It is also and most importantly the seat of a person's identity. Multiple trauma adds a life-threatening dimension to the physical and psychological impact of a facial trauma.

  14. Bubble drag reduction requires large bubbles

    NASA Astrophysics Data System (ADS)

    Verschoof, Ruben; van der Veen, Roeland; Sun, Chao; Lohse, Detlef

    2016-11-01

    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. A few volume percent (<= 4 %) of bubbles can reduce the overall drag up to 40% and beyond. However, the exact mechanism is unknown, thus hindering further progress and optimization. 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. We acknowledge support from STW and FOM.

  15. Bubbly Cavitation Flows.

    DTIC Science & Technology

    1991-03-31

    and 12. Comparison is also made with analytical predictions based on the Rayleigh - Plesset equations. In addition to the single bubble studies, the...bubble maximum size distributions and those predicted using the measured nuclei number distribution and the Rayleigh - Plesset model for the bubble dyna...tions 7, 9, 11, 12, 13 examined travelling bubble cavitation on two classic axisymmetric headforms (a Schiebe body and the ITTC headform) and, with the

  16. Acoustic bubble traps

    NASA Astrophysics Data System (ADS)

    Geisler, Reinhard; Kurz, Thomas; Lauterborn, Werner

    2000-07-01

    A small, oscillating bubble in a liquid can be trapped in the antinode of an acoustic standing wave field. Bubble stability is required for the study of single bubble sonoluminescence (SBSL). The properties of the acoustic resonator are essential for the stable trapping of sonoluminescing bubbles. Resonators can be chosen according to the intended application: size and geometry can be varied in a wide range. In this work, the acoustic responses of different resonators were measured by means of holographic interferometry, hydrophones and a laser vibrometer. Also, high-speed photography was used to observe the bubble dynamics. Several single, stable sonoluminescent bubbles were trapped simultaneously within an acoustic resonator in the pressure antinodes of a higher harmonic mode (few bubble sonoluminescence, FBSL).

  17. Trauma Ultrasound.

    PubMed

    Wongwaisayawan, Sirote; Suwannanon, Ruedeekorn; Prachanukool, Thidathit; Sricharoen, Pungkava; Saksobhavivat, Nitima; Kaewlai, Rathachai

    2015-10-01

    Ultrasound plays a pivotal role in the evaluation of acute trauma patients through the use of multi-site scanning encompassing abdominal, cardiothoracic, vascular and skeletal scans. In a high-speed polytrauma setting, because exsanguinations are the primary cause of trauma morbidity and mortality, ultrasound is used for quick and accurate detection of hemorrhages in the pericardial, pleural, and peritoneal cavities during the primary Advanced Trauma Life Support (ATLS) survey. Volume status can be assessed non-invasively with ultrasound of the inferior vena cava (IVC), which is a useful tool in the initial phase and follow-up evaluations. Pneumothorax can also be quickly detected with ultrasound. During the secondary survey and in patients sustaining low-speed or localized trauma, ultrasound can be used to help detect abdominal organ injuries. This is particularly helpful in patients in whom hemoperitoneum is not identified on an initial scan because findings of organ injuries will expedite the next test, often computed tomography (CT). Moreover, ultrasound can assist in detection of fractures easily obscured on radiography, such as rib and sternal fractures.

  18. Establishing Standards for Trauma Nursing Education: The Central Ohio Trauma System's Approach.

    PubMed

    Haley, Kathy; Martin, Stacey; Kilgore, Jane; Lang, Carrie; Rozzell, Monica; Coffey, Carla; Eley, Scott; Light, Andrea; Hubartt, Jeff; Kovach, Sherri; Deppe, Sharon

    Trauma nursing requires mastering a highly specialized body of knowledge. Expert nursing care is expected to be offered throughout the hospital continuum, yet identifying the necessary broad-based objectives for nurses working within this continuum has often been difficult to define. Trauma nurse leaders and educators from 7 central and southeastern Ohio trauma centers and 1 regional trauma organization convened to establish an approach to standardizing trauma nursing education from a regional perspective. Forty-two trauma nursing educational objectives were identified. The Delphi method was used to narrow the list to 3 learning objectives to serve as the framework for a regional trauma nursing education guideline. Although numerous trauma nursing educational needs were identified across the continuum of care, a lack of clearly defined standards exists. Recognizing and understanding the educational preparation and defined standards required for nurses providing optimal trauma care are vital for a positive impact on patient outcomes. This regional trauma nursing education guideline is a novel model and can be used to assist trauma care leaders in standardizing trauma education within their hospital, region, or state. The use of this model may also lead to the identification of gaps within trauma educational systems.

  19. Trauma, attachment, and intimate relationships.

    PubMed

    Zurbriggen, Eileen L; Gobin, Robyn L; Kaehler, Laura A

    2012-01-01

    Intimate relationships can both affect and be affected by trauma and its sequelae. This special issue highlights research on trauma, attachment, and intimate relationships. Several themes emerged. One theme is the exploration of the associations between a history of trauma and relational variables, with an emphasis on models using these variables as mediators. Given the significance of secure attachment for healthy relationships, it is not surprising that attachment emerges as another theme of this issue. Moreover, a key component of relationships is trust, and so a further theme of this issue is betrayal trauma (J. J. Freyd, 1996 ). As the work included in this special issue makes clear, intimate relationships of all types are important for the psychological health of those exposed to traumatic events. In order to best help trauma survivors and those close to them, it is imperative that research exploring these issues be presented to research communities, clinical practitioners, and the public in general. This special issue serves as one step toward that objective.

  20. Do Some Students Need Special Protection From Research on Sex and Trauma? New Evidence for Young Adult Resilience in "Sensitive Topics" Research.

    PubMed

    Rinehart, Jenny K; Nason, Erica E; Yeater, Elizabeth A; Miller, Geoffrey F

    2017-01-01

    Institutional review boards (IRBs) have expressed concerns that certain individuals or groups, such as participants who are younger, ethnic minorities, or who have certain psychological or personality traits, may be particularly distressed when participating in "sensitive topics" research. This study examined the effects of several demographic and individual difference factors (i.e., age, sex, ethnicity, religiosity, Big Five personality traits, and baseline psychological distress levels) on reactions to participation in sensitive topics research. Participants were 504 undergraduates who completed an extensive battery of either trauma/sex questionnaires or cognitive tests and rated their positive and negative emotional reactions and the perceived benefits and mental costs of participating. They also compared research participation to normal life stressors. Our findings indicated that individual difference and demographic risk factors do not increase participant distress after participating in sex/trauma research over and above that experienced after participating in traditionally minimal-risk cognitive tasks. Participants generally found research participation less distressing than normal life stressors and even enjoyable.

  1. Chest trauma.

    PubMed

    Budassi, S A

    1978-09-01

    For any patient with obvious or suspected chest trauma, one must first assure an adequate airway and adequate ventilation. One should never hesitate to administer oxygen to a victim with a chest injury. The nurse should be concerned with adequate circulation--this may mean the administration of intravenous fluids, specifically volume expanders, via large-bore cannulae. Any obvious open chest wound should be sealed, and any fractures should be splinted. These patients should be rapidly transported to the nearest Emergency Department capable of handling this type of injury. The majority of patients who arrive in the Emergency Department following blunt or penetrating trauma should be considered to be in critical condition until proven otherwise. On presentation, it is essential to recognize those signs, symptoms, and laboratory values that identify the patient's condition as life-threatening. Simple recognition of these signs and symptoms and early appropriate intervention may alter an otherwise fatal outcome.

  2. Gas bubble detector

    NASA Technical Reports Server (NTRS)

    Mount, Bruce E. (Inventor); Burchfield, David E. (Inventor); Hagey, John M. (Inventor)

    1995-01-01

    A gas bubble detector having a modulated IR source focused through a bandpass filter onto a venturi, formed in a sample tube, to illuminate the venturi with modulated filtered IR to detect the presence of gas bubbles as small as 0.01 cm or about 0.004 in diameter in liquid flowing through the venturi. Means are provided to determine the size of any detected bubble and to provide an alarm in the absence of liquid in the sample tube.

  3. Tightrope walking bubbles

    NASA Astrophysics Data System (ADS)

    de Maleprade, Helene; Clanet, Christophe; Quere, David

    2016-11-01

    A fiber can hold a certain amount of liquid, which allows us to capture flying drops and control their motion. Immersed in water, a fiber can efficiently capture air bubbles only if it is hydrophobic. Using a superhydrophobic coating on an inclined wire, we experimentally control the rising velocity of air bubbles walking along the tightrope. We discuss the nature of the friction around the walker, and the resulting speed of bubbles.

  4. A bubble detection system for propellant filling pipeline

    SciTech Connect

    Wen, Wen; Zong, Guanghua; Bi, Shusheng

    2014-06-15

    This paper proposes a bubble detection system based on the ultrasound transmission method, mainly for probing high-speed bubbles in the satellite propellant filling pipeline. First, three common ultrasonic detection methods are compared and the ultrasound transmission method is used in this paper. Then, the ultrasound beam in a vertical pipe is investigated, suggesting that the width of the beam used for detection is usually smaller than the internal diameter of the pipe, which means that when bubbles move close to the pipe wall, they may escape from being detected. A special device is designed to solve this problem. It can generate the spiral flow to force all the bubbles to ascend along the central line of the pipe. In the end, experiments are implemented to evaluate the performance of this system. Bubbles of five different sizes are generated and detected. Experiment results show that the sizes and quantity of bubbles can be estimated by this system. Also, the bubbles of different radii can be distinguished from each other. The numerical relationship between the ultrasound attenuation and the bubble radius is acquired and it can be utilized for estimating the unknown bubble size and measuring the total bubble volume.

  5. Bubble nonlinear dynamics and stimulated scattering process

    NASA Astrophysics Data System (ADS)

    Jie, Shi; De-Sen, Yang; Sheng-Guo, Shi; Bo, Hu; Hao-Yang, Zhang; Shi-Yong, Hu

    2016-02-01

    A complete understanding of the bubble dynamics is deemed necessary in order to achieve their full potential applications in industry and medicine. For this purpose it is first needed to expand our knowledge of a single bubble behavior under different possible conditions including the frequency and pressure variations of the sound field. In addition, stimulated scattering of sound on a bubble is a special effect in sound field, and its characteristics are associated with bubble oscillation mode. A bubble in liquid can be considered as a representative example of nonlinear dynamical system theory with its resonance, and its dynamics characteristics can be described by the Keller-Miksis equation. The nonlinear dynamics of an acoustically excited gas bubble in water is investigated by using theoretical and numerical analysis methods. Our results show its strongly nonlinear behavior with respect to the pressure amplitude and excitation frequency as the control parameters, and give an intuitive insight into stimulated sound scattering on a bubble. It is seen that the stimulated sound scattering is different from common dynamical behaviors, such as bifurcation and chaos, which is the result of the nonlinear resonance of a bubble under the excitation of a high amplitude acoustic sound wave essentially. The numerical analysis results show that the threshold of stimulated sound scattering is smaller than those of bifurcation and chaos in the common condition. Project supported by the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT1228) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant Nos. 11204050 and 11204049).

  6. Prospects for bubble fusion

    SciTech Connect

    Nigmatulin, R.I.; Lahey, R.T. Jr.

    1995-09-01

    In this paper a new method for the realization of fusion energy is presented. This method is based on the superhigh compression of a gas bubble (deuterium or deuterium/thritium) in heavy water or another liquid. The superhigh compression of a gas bubble in a liquid is achieved through forced non-linear, non-periodic resonance oscillations using moderate amplitudes of forcing pressure. The key feature of this new method is a coordination of the forced liquid pressure change with the change of bubble volume. The corresponding regime of the bubble oscillation has been called {open_quotes}basketball dribbling (BD) regime{close_quotes}. The analytical solution describing this process for spherically symmetric bubble oscillations, neglecting dissipation and compressibility of the liquid, has been obtained. This solution shown no limitation on the supercompression of the bubble and the corresponding maximum temperature. The various dissipation mechanisms, including viscous, conductive and radiation heat losses have been considered. It is shown that in spite of these losses it is possible to achieve very high gas bubble temperatures. This because the time duration of the gas bubble supercompression becomes very short when increasing the intensity of compression, thus limiting the energy losses. Significantly, the calculated maximum gas temperatures have shown that nuclear fusion may be possible. First estimations of the affect of liquid compressibility have been made to determine possible limitations on gas bubble compression. The next step will be to investigate the role of interfacial instability and breaking down of the bubble, shock wave phenomena around and in the bubble and mutual diffusion of the gas and the liquid.

  7. Acoustical emission from bubbles

    NASA Astrophysics Data System (ADS)

    Longuet-Higgins, Michael S.

    1991-12-01

    The scientific objectives of this report are to investigate the dynamics of bubbles formed from a free surface (particularly the upper surface of the ocean) by breaking waves, and the resulting emission of underwater sound. The chief natural source of underwater sound in the ocean at frequencies from 0.5 to 50 kHz is known to be the acoustical emission from newly-formed bubbles and bubble clouds, particularly those created by breaking waves and rain. Attention has been drawn to the occurrence of high-speed jets directed into the bubble just after bubble closure. They have been observed both in rain-drop impacts and in the release of bubbles from an underwater nozzle. Qualitatively they are similar to the inward jets seen in the collapse of a cavitation bubble. There is also a similarity to the highly-accelerated upward jets in standing water waves (accelerations greater than 20g) or in bubbles bursting at a free surface. We have adopted a theoretical approach based on the dynamics of incompressible fluids with a free surface.

  8. Evaporation, Boiling and Bubbles

    ERIC Educational Resources Information Center

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  9. Let Them Blow Bubbles.

    ERIC Educational Resources Information Center

    Korenic, Eileen

    1988-01-01

    Describes a series of activities and demonstrations involving the science of soap bubbles. Starts with a recipe for bubble solution and gives instructions for several activities on topics such as density, interference colors, optics, static electricity, and galaxy formation. Contains some background information to help explain some of the effects.…

  10. Simulating Surfzone Bubbles

    DTIC Science & Technology

    2012-09-30

    D (Ripple) and 3-D ( Truchas ) Navier- Stokes solvers. In the continuation of this work, our objectives are to: 1) Implement a physics-based...a bubble phase with multiple bubble size (or, more accurately, mass) bins. The existing 3-D model Truchas has been extended to include Carrica et al

  11. Bubble collision with gravitation

    SciTech Connect

    Hwang, Dong-il; Lee, Bum-Hoon; Lee, Wonwoo; Yeom, Dong-han E-mail: bhl@sogang.ac.kr E-mail: innocent.yeom@gmail.com

    2012-07-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  12. Interfacial Bubble Deformations

    NASA Astrophysics Data System (ADS)

    Seymour, Brian; Shabane, Parvis; Cypull, Olivia; Cheng, Shengfeng; Feitosa, Klebert

    Soap bubbles floating at an air-water experience deformations as a result of surface tension and hydrostatic forces. In this experiment, we investigate the nature of such deformations by taking cross-sectional images of bubbles of different volumes. The results show that as their volume increases, bubbles transition from spherical to hemispherical shape. The deformation of the interface also changes with bubble volume with the capillary rise converging to the capillary length as volume increases. The profile of the top and bottom of the bubble and the capillary rise are completely determined by the volume and pressure differences. James Madison University Department of Physics and Astronomy, 4VA Consortium, Research Corporation for Advancement of Science.

  13. Bubbles in liquids with phase transition. Part 1. On phase change of a single vapor bubble in liquid water

    NASA Astrophysics Data System (ADS)

    Dreyer, Wolfgang; Duderstadt, Frank; Hantke, Maren; Warnecke, Gerald

    2012-11-01

    In the forthcoming second part of this paper a system of balance laws for a multi-phase mixture with many dispersed bubbles in liquid is derived where phase transition is taken into account. The exchange terms for mass, momentum and energy explicitly depend on evolution laws for total mass, radius and temperature of single bubbles. Therefore in the current paper we consider a single bubble of vapor and inert gas surrounded by the corresponding liquid phase. The creation of bubbles, e.g. by nucleation is not taken into account. We study the behavior of this bubble due to condensation and evaporation at the interface. The aim is to find evolution laws for total mass, radius and temperature of the bubble, which should be as simple as possible but consider all relevant physical effects. Special attention is given to the effects of surface tension and heat production on the bubble dynamics as well as the propagation of acoustic elastic waves by including slight compressibility of the liquid phase. Separately we study the influence of the three phenomena heat conduction, elastic waves and phase transition on the evolution of the bubble. We find ordinary differential equations that describe the bubble dynamics. It turns out that the elastic waves in the liquid are of greatest importance to the dynamics of the bubble radius. The phase transition has a strong influence on the evolution of the temperature, in particular at the interface. Furthermore the phase transition leads to a drastic change of the water content in the bubble. It is shown that a rebounding bubble is only possible, if it contains in addition an inert gas. In Part 2 of the current paper the equations derived are sought in order to close the system of equations for multi-phase mixture balance laws for dispersed bubbles in liquids involving phase change.

  14. Bubble motion measurements during foam drainage and coarsening.

    PubMed

    Maurdev, G; Saint-Jalmes, A; Langevin, D

    2006-08-15

    We have studied bubble motion within a column of foam allowed to undergo free drainage. We have measured bubble motion upward with time and as a function of their initial positions. Depending on the gas used, which sets the coarsening and drainage rates, different bubble upward motion types have been identified (constant speed, acceleration or deceleration) and explained in relation with liquid downward flows. The proofs of the consistency between bubble upward motion and liquid downward flow are obtained both by comparing the bubble motion curves to the liquid drainage ones, and by comparing the time variations of the liquid fraction extracted from bubble motion to direct liquid fraction measurements by electrical conductimetry. The agreement between bubble position tracking and electrical conductivity shows in particular that it is possible to determine the drainage regime from such simple bubble motion measurements. This work also allowed us to demonstrate a special case of foam coarsening and expansion, occurring when the foam gas is less soluble than the outside one, caused by diffusion of this external gas into the foam. All these results allow us to build a picture of drainage and coarsening seen from the bubble point of view.

  15. Tribonucleation of bubbles

    PubMed Central

    Wildeman, Sander; Lhuissier, Henri; Sun, Chao; Lohse, Detlef; Prosperetti, Andrea

    2014-01-01

    We report on the nucleation of bubbles on solids that are gently rubbed against each other in a liquid. The phenomenon is found to depend strongly on the material and roughness of the solid surfaces. For a given surface, temperature, and gas content, a trail of growing bubbles is observed if the rubbing force and velocity exceed a certain threshold. Direct observation through a transparent solid shows that each bubble in the trail results from the early coalescence of several microscopic bubbles, themselves detaching from microscopic gas pockets forming between the solids. From a detailed study of the wear tracks, with atomic force and scanning electron microscopy imaging, we conclude that these microscopic gas pockets originate from a local fracturing of the surface asperities, possibly enhanced by chemical reactions at the freshly created surfaces. Our findings will be useful either for preventing undesired bubble formation or, on the contrary, for “writing with bubbles,” i.e., creating controlled patterns of microscopic bubbles. PMID:24982169

  16. Bubble Impact with a Solid Wall

    NASA Astrophysics Data System (ADS)

    Garg, Vishrut; Thete, Sumeet; Basaran, Osman

    2016-11-01

    In diverse natural and industrial processes, and in particular in process equipment widely used in oil and gas production, bubbles and drops that are immersed in a continuous liquid phase frequently collide with solid walls. In this talk, the impact with a solid wall of a gas bubble that is surrounded by a liquid that is either a Newtonian or a non-Newtonian fluid is analyzed by numerical simulation. Special attention is paid to the thin film that forms between the approaching bubble and the solid wall. Flow regimes that arise as the film thickness decreases are scrutinized and rationalized by comparison of the computational predictions to well-known and new analytical results from lubrication theory based thin film literature. Finally, flow transitions that occur as the lubrication theory breaks down and inertia becomes significant are investigated.

  17. Bubble core field modification by residual electrons inside the bubble

    SciTech Connect

    Wu Haicheng; Xie Baisong; Zhao Xueyan; Zhang Shan; Hong Xueren; Liu Mingping

    2010-11-15

    Bubble core field modification due to the nondepleted electrons present inside the bubble is investigated theoretically. These residual electrons induce charge and current densities that can induce the bubble core field modification as well as the bubble shape change. It is found that the electrons entering into the bubble move backward at almost light speed and would weaken the transverse bubble fields. This reduces the ratio of longitudinal to transverse radius of the bubble. For the longitudinal bubble field, two effects compensate with each other because of their competition between the enhancement by the shortening of bubble shape and the reduction by the residual electrons. Therefore the longitudinal field is hardly changeable. As a comparison we perform particle-in-cell simulations and it is found that the results from theoretical consideration are consistent with simulation results. Implication of the modification of fields on bubble electron acceleration is also discussed briefly.

  18. Simulation of special bubble detectors for PICASSO.

    PubMed

    Azuelos, G; Barnabé-Heider, M; Behnke, E; Clark, K; Di Marco, M; Doane, P; Feighery, W; Genest, M-H; Gornea, R; Guénette, R; Kanagalingam, S; Krauss, C; Leroy, C; Lessard, L; Levine, I; Martin, J P; Noble, A J; Noulty, R; Shore, S N; Wichoski, U; Zacek, V

    2006-01-01

    The PICASSO project is a cold dark matter (CDM) search experiment relying on the superheated droplet technique. The detectors use superheated freon liquid droplets (active material) dispersed and trapped in a polymerised gel. This detection technique is based on the phase transition of superheated droplets at about room temperature and ambient pressure. The phase transition is induced by nuclear recoils when an atomic nucleus in the droplets interacts with incoming subatomic particles. This includes CDM particles candidate as the neutralino (a yet-to-discover particle predicted in extensions of the standard model of particle physics). Simulations performed to understand the detector response to neutrons and alpha particles are presented along with corresponding data obtained at the Montreal Laboratory.

  19. Viscosity Destabilizes Sonoluminescing Bubbles

    NASA Astrophysics Data System (ADS)

    Toegel, Ruediger; Luther, Stefan; Lohse, Detlef

    2006-03-01

    In single-bubble sonoluminescence (SBSL) microbubbles are trapped in a standing sound wave, typically in water or water-glycerol mixtures. However, in viscous liquids such as glycol, methylformamide, or sulphuric acid it is not possible to trap the bubble in a stable position. This is very peculiar as larger viscosity normally stabilizes the dynamics. Suslick and co-workers call this new mysterious state of SBSL “moving-SBSL.” We identify the history force (a force nonlocal in time) as the origin of this destabilization and show that the instability is parametric. A force balance model quantitatively accounts for the observed quasiperiodic bubble trajectories.

  20. Viscosity destabilizes sonoluminescing bubbles.

    PubMed

    Toegel, Ruediger; Luther, Stefan; Lohse, Detlef

    2006-03-24

    In single-bubble sonoluminescence (SBSL) microbubbles are trapped in a standing sound wave, typically in water or water-glycerol mixtures. However, in viscous liquids such as glycol, methylformamide, or sulphuric acid it is not possible to trap the bubble in a stable position. This is very peculiar as larger viscosity normally stabilizes the dynamics. Suslick and co-workers call this new mysterious state of SBSL "moving-SBSL." We identify the history force (a force nonlocal in time) as the origin of this destabilization and show that the instability is parametric. A force balance model quantitatively accounts for the observed quasiperiodic bubble trajectories.

  1. Rotating bubble membrane radiator

    DOEpatents

    Webb, Brent J.; Coomes, Edmund P.

    1988-12-06

    A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.

  2. Cardiovascular bubble dynamics.

    PubMed

    Bull, Joseph L

    2005-01-01

    Gas bubbles can form in the cardiovascular system as a result of patho-physiological conditions or can be intentionally introduced for diagnostic or therapeutic reasons. The dynamic behavior of these bubbles is caused by a variety of mechanisms, such as inertia, pressure, interfacial tension, viscosity, and gravity. We review recent advances in the fundamental mechanics and applications of cardiovascular bubbles, including air embolism, ultrasound contrast agents, targeted microbubbles for drug delivery and molecular imaging, cavitation-induced tissue erosion for ultrasonic surgery, microbubble-induced angiogenesis and arteriogenesis, and gas embolotherapy.

  3. Chemistry in Soap Bubbles.

    ERIC Educational Resources Information Center

    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)

  4. What's in a Bubble?

    ERIC Educational Resources Information Center

    Saunderson, Megan

    2000-01-01

    Describes a unit on detergents and bubbles that establishes an interest in the properties of materials and focuses on active learning involving both hands- and minds-on learning rather than passive learning. (ASK)

  5. Blowing magnetic skyrmion bubbles

    NASA Astrophysics Data System (ADS)

    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

    2015-07-01

    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.

  6. Curvature-driven bubbles or droplets on the spiral surface

    PubMed Central

    Li, Shanpeng; Liu, Jianlin; Hou, Jian

    2016-01-01

    Directional motion of droplets or bubbles can often be observed in nature and our daily life, and this phenomenon holds great potential in many engineering areas. The study shows that droplets or bubbles can be driven to migrate perpetually on some special substrates, such as the Archimedean spiral, the logarithmic spiral and a cantilever sheet in large deflection. It is found that a bubble approaches or deviates from the position with highest curvature of the substrate, when it is on the concave or convex side. This fact is helpful to explain the repelling water capability of Nepenthes alata. Based on the force and energy analysis, the mechanism of the bubble migration is well addressed. These findings pave a new way to accurately manipulate droplet or bubble movement, which bring inspirations to the design of microfluidic and water harvesting devices, as well as oil displacement and ore filtration. PMID:27885261

  7. Curvature-driven bubbles or droplets on the spiral surface

    NASA Astrophysics Data System (ADS)

    Li, Shanpeng; Liu, Jianlin; Hou, Jian

    2016-11-01

    Directional motion of droplets or bubbles can often be observed in nature and our daily life, and this phenomenon holds great potential in many engineering areas. The study shows that droplets or bubbles can be driven to migrate perpetually on some special substrates, such as the Archimedean spiral, the logarithmic spiral and a cantilever sheet in large deflection. It is found that a bubble approaches or deviates from the position with highest curvature of the substrate, when it is on the concave or convex side. This fact is helpful to explain the repelling water capability of Nepenthes alata. Based on the force and energy analysis, the mechanism of the bubble migration is well addressed. These findings pave a new way to accurately manipulate droplet or bubble movement, which bring inspirations to the design of microfluidic and water harvesting devices, as well as oil displacement and ore filtration.

  8. Blowing DNA bubbles.

    PubMed

    Severin, N; Zhuang, W; Ecker, C; Kalachev, A A; Sokolov, I M; Rabe, J P

    2006-11-01

    We report here experimental observations which indicate that topologically or covalently formed polymer loops embedded in an ultrathin liquid film on a solid substrate can be "blown" into circular "bubbles" during scanning force microscopy (SFM) imaging. In particular, supercoiled vector DNA has been unraveled, moved, stretched, and overstretched to two times its B-form length and then torn apart. We attribute the blowing of the DNA bubbles to the interaction of the tapping SFM tip with the ultrathin liquid film.

  9. 2012 Problem 8: Bubbles

    NASA Astrophysics Data System (ADS)

    Zhu, Kejing; Xia, Qing; Wang, Sihui; Zhou, Huijun

    2015-10-01

    When a large number of bubbles exist in the water, an object may float on the surface or sink. The assumption of equivalent density is proposed in this article to explain the concrete example. According to the assumption, an object is floatable only if its density is less than the equivalent density of the water-bubble mixture. This conclusion is supported by the floating experiment and by measuring the pressure underwater to a satisfactory approximation.

  10. Bubble coalescence in magmas

    NASA Technical Reports Server (NTRS)

    Herd, Richard A.; Pinkerton, Harry

    1993-01-01

    The most important factors governing the nature of volcanic eruptions are the primary volatile contents, the ways in which volatiles exsolve, and how the resulting bubbles grow and interact. In this contribution we assess the importance of bubble coalescence. The degree of coalescence in alkali basalts has been measured using Image Analysis techniques and it is suggested to be a process of considerable importance. Binary coalescence events occur every few minutes in basaltic melts with vesicularities greater than around 35 percent.

  11. Energy cascading by triple-bubble interactions via time-delayed control

    NASA Astrophysics Data System (ADS)

    Lin, Yen-Liang; Chang, Chia-Ming; Yang, I.-Da; Chieng, Ching-Chang; Tseng, Fan-Gang

    2012-01-01

    The triple-bubble interaction controlled by a precise time-delayed technique was investigated in detail with respect to different ignition times, heater spaces and sequential firing modes to promote efficient energy cascading and concentration. The target bubble, which was generated under a specific delay time with two auxiliary bubbles, can have a volume that is two or almost three times larger than that of a single bubble. This result overcomes the limitation of energy usage on an explosive microbubble under a constant heat flux. As the heater space decreases, stronger bubble-bubble interactions were obtained due to the hydrodynamic effect and the intensive pressure wave emission, resulting in highly enhancing and depressing bubble dynamics. Other interesting phenomena, such as bubble shifting, mushroom-shape bubble, rod-shape bubble and bubble extension among heaters, were also recorded by a high-speed phase-averaged stroboscopic technique, displaying special non-spherical bubble dynamics. Artificial manipulation of bubble behavior was further conducted in a two-level sequential firing process. Using various volumetric combinations, the adjustable multi-level fluid transportation can be realized by a digital time-delayed control. The above-mentioned information can be applied to not only the design and operation of inkjet printheads but also cavitation research and fluid pumping in microdevices.

  12. Clustering in Bubble Suspensions

    NASA Astrophysics Data System (ADS)

    Zenit, Roberto

    2000-11-01

    A monidisperse bubble suspension is studied experimentally for the limit in which the Weber number is small and the Reynolds number is large. For this regime the suspension can be modeled using potential flow theory to describe the dynamics of the interstitial fluid. Complete theoretical descriptions have been composed (Spelt and Sangani, 1998) to model the behavior of these suspensions. Bubble clustering is a natural instability that arises from the potential flow considerations, in which bubbles tend to align in horizontal rafts as they move upwards. The appearance of bubble clusters was recently corroborated experimentally by Zenit et al. (2000), who found that although clusters did appear, their strength was not as strong as the predictions. Experiments involving gravity driven shear flows are used to explain the nature of the clustering observed in these type of flows. Balances of the bubble phase pressure (in terms of a calculated diffusion coefficient) and the Maxwell pressure (from the potential flow description) are presented to predict the stability of the bubble suspension. The predictions are compared with experimental results.

  13. On the Physics of Fizziness: How liquid properties control bursting bubble aerosol production?

    NASA Astrophysics Data System (ADS)

    Ghabache, Elisabeth; Antkowiak, Arnaud; Josserand, Christophe; Seon, Thomas

    2014-11-01

    Either in a champagne glass or at the oceanic scales, the tiny capillary bubbles rising at the surface burst in ejecting myriads of droplets. Focusing on the ejected droplets produced by a single bubble, we investigate experimentally how liquid properties and bubble size affect their characteristics: number, ejection velocities, sizes and ejection heights. These results allow us to finely tune the bursting bubble aerosol production. In the context of champagne industry, aerosols play a major role by spreading wine aroma above the glass. We demonstrate that this champagne fizz can be enhanced by selecting the wine viscosity and the bubble size, thanks to specially designed glass.

  14. The dynamics of histotripsy bubbles

    NASA Astrophysics Data System (ADS)

    Kreider, Wayne; Bailey, Michael R.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Crum, Lawrence A.

    2011-09-01

    Histotripsy describes treatments in which high-amplitude acoustic pulses are used to excite bubbles and erode tissue. Though tissue erosion can be directly attributed to bubble activity, the genesis and dynamics of bubbles remain unclear. Histotripsy lesions that show no signs of thermal coagulative damage have been generated with two different acoustic protocols: relatively long acoustic pulses that produce local boiling within milliseconds and relatively short pulses that are higher in amplitude but likely do not produce boiling. While these two approaches are often distinguished as `boiling' versus `cavitation', such labels can obscure similarities. In both cases, a bubble undergoes large changes in radius and vapor is transported into and out of the bubble as it oscillates. Moreover, observations from both approaches suggest that bubbles grow to a size at which they cease to collapse violently. In order to better understand the dynamics of histotripsy bubbles, a single-bubble model has been developed that couples acoustically excited bubble motions to the thermodynamic state of the surrounding liquid. Using this model for bubbles exposed to histotripsy sound fields, simulations suggest that two mechanisms can act separately or in concert to lead to the typically observed bubble growth. First, nonlinear acoustic propagation leads to the evolution of shocks and an asymmetry in the positive and negative pressures that drive bubble motion. This asymmetry can have a rectifying effect on bubble oscillations whereby the bubble grows on average during each acoustic cycle. Second, vapor transport to/from the bubble tends to produce larger bubbles, especially at elevated temperatures. Vapor transport by itself can lead to rectified bubble growth when the ambient temperature exceeds 100 °C (`boiling') or local heating in the vicinity of the bubble leads to a superheated boundary layer.

  15. Statistical equilibrium of bubble oscillations in dilute bubbly flows

    PubMed Central

    Colonius, Tim; Hagmeijer, Rob; Ando, Keita; Brennen, Christopher E.

    2008-01-01

    The problem of predicting the moments of the distribution of bubble radius in bubbly flows is considered. The particular case where bubble oscillations occur due to a rapid (impulsive or step change) change in pressure is analyzed, and it is mathematically shown that in this case, inviscid bubble oscillations reach a stationary statistical equilibrium, whereby phase cancellations among bubbles with different sizes lead to time-invariant values of the statistics. It is also shown that at statistical equilibrium, moments of the bubble radius may be computed using the period-averaged bubble radius in place of the instantaneous one. For sufficiently broad distributions of bubble equilibrium (or initial) radius, it is demonstrated that bubble statistics reach equilibrium on a time scale that is fast compared to physical damping of bubble oscillations due to viscosity, heat transfer, and liquid compressibility. The period-averaged bubble radius may then be used to predict the slow changes in the moments caused by the damping. A benefit is that period averaging gives a much smoother integrand, and accurate statistics can be obtained by tracking as few as five bubbles from the broad distribution. The period-averaged formula may therefore prove useful in reducing computational effort in models of dilute bubbly flow wherein bubbles are forced by shock waves or other rapid pressure changes, for which, at present, the strong effects caused by a distribution in bubble size can only be accurately predicted by tracking thousands of bubbles. Some challenges associated with extending the results to more general (nonimpulsive) forcing and strong two-way coupled bubbly flows are briefly discussed. PMID:19547725

  16. Colliding with a crunching bubble

    SciTech Connect

    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.

  17. A Bubble Bursts

    NASA Technical Reports Server (NTRS)

    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.

  18. The Dueling Bubble Experiment

    NASA Astrophysics Data System (ADS)

    Roy, Anshuman; Borrell, Marcos; Felts, John; Leal, Gary; Hirsa, Amir

    2007-11-01

    When two drops or bubbles are brought into close proximity to each other, the thin film of the fluid between them drains as they are squeezed together. If the film becomes thin enough that intermolecular forces of attraction overwhelm capillary forces, the drops/bubbles coalesce and the time it takes for this to happen, starting from the point of apparent contact is referred to as the drainage time. One practical version of this scenario occurs during the formation of foams, when the thin film forms between gas bubbles that are growing in volume with time. We performed an experimental study that is intended to mimic this process in which the two drops (or bubbles) in the size range of 50-100 microns diameter are created by oozing a liquid/gas out of two capillaries of diameter less than 100 microns directly facing each other and immersed in a second fluid. We present measurements of drainage times for the cases of very low viscosity ratios PDMS drops in Castor oil (less than 0.05) and bubbles of air in PDMS, and highlight the differences that arise in part due to the different boundary conditions for thin film drainage for liquid-liquid versus gas-liquid systems, and in part due to the different Hamaker constants for the two systems.

  19. Bubbles of Metamorphosis

    NASA Astrophysics Data System (ADS)

    Prakash, Manu

    2011-11-01

    Metamorphosis presents a puzzling challenge where, triggered by a signal, an organism abruptly transforms its entire shape and form. Here I describe the role of physical fluid dynamic processes during pupal metamorphosis in flies. During early stages of pupation of third instar larvae into adult flies, a physical gas bubble nucleates at a precise temporal and spatial location, as part of the normal developmental program in Diptera. Although its existence has been known for the last 100 years, the origin and control of this ``cavitation'' event has remained completely mysterious. Where does the driving negative pressure for bubble nucleation come from? How is the location of the bubble nucleation site encoded in the pupae? How do molecular processes control such a physical event? What is the role of this bubble during development? Via developing in-vivo imaging techniques, direct bio-physical measurements in live insect pupal structures and physical modeling, here I elucidate the physical mechanism for appearance and disappearance of this bubble and predict the site of nucleation and its exact timing. This new physical insight into the process of metamorphosis also allows us to understand the inherent design of pupal shell architectures in various species of insects. Milton Award, Harvard Society of Fellows; Terman Fellowship, Stanford

  20. Bubbles from nothing

    SciTech Connect

    Blanco-Pillado, Jose J.; Ramadhan, Handhika S.; Shlaer, Benjamin E-mail: handhika@cosmos.phy.tufts.edu

    2012-01-01

    Within the framework of flux compactifications, we construct an instanton describing the quantum creation of an open universe from nothing. The solution has many features in common with the smooth 6d bubble of nothing solutions discussed recently, where the spacetime is described by a 4d compactification of a 6d Einstein-Maxwell theory on S{sup 2} stabilized by flux. The four-dimensional description of this instanton reduces to that of Hawking and Turok. The choice of parameters uniquely determines all future evolution, which we additionally find to be stable against bubble of nothing instabilities.

  1. Multivariate bubbles and antibubbles

    NASA Astrophysics Data System (ADS)

    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.

  2. Understanding and Addressing the Trauma from Abuse: A Model of Safety, Reconnection, and Integration for Victims of Abuse. A Specialized Training Program Designed To Enhance the Competency of Caseworkers, Adoptive & Foster Parents.

    ERIC Educational Resources Information Center

    Schatz, Mona Struhsaker; Rigg, Georgia A.

    Although the trauma that children experience in abusive situations differs from the trauma of a disaster, its effects are just as profound. The information and skills that caseworkers need to assess families and children who have been traumatized, to make more appropriate treatment planning decisions, and to carry out their professional roles with…

  3. Fluid Dynamics of Bubbly Liquids

    NASA Technical Reports Server (NTRS)

    Tsang, Y. H.; Koch, D. L.; Zenit, R.; Sangani, A.; Kushch, V. I.; Spelt, P. D. M.; Hoffman, M.; Nahra, H.; Fritz, C.; Dolesh, R.

    2002-01-01

    Experiments have been performed to study the average flow properties of inertially dominated bubbly liquids which may be described by a novel analysis. Bubbles with high Reynolds number and low Weber number may produce a fluid velocity disturbance that can be approximated by a potential flow. We studied the behavior of suspensions of bubbles of about 1.5 mm diameter in vertical and inclined channels. The suspension was produced using a bank of 900 glass capillaries with inner diameter of about 100 microns in a quasi-steady fashion. In addition, salt was added to the suspension to prevent bubble-bubble coalescence. As a result, a nearly monodisperse suspension of bubble was produced. By increasing the inclination angle, we were able to explore an increasing amount of shear to buoyancy motion. A pipe flow experiment with the liquid being recirculated is under construction. This will provide an even larger range of shear to buoyancy motion. We are planning a microgravity experiment in which a bubble suspension is subjected to shearing in a couette cell in the absence of a buoyancy-driven relative motion of the two phases. By employing a single-wire, hot film anemometer, we were able to obtain the liquid velocity fluctuations. The shear stress at the wall was measured using a hot film probe flush mounted on the wall. The gas volume fraction, bubble velocity, and bubble velocity fluctuations were measured using a homemade, dual impedance probe. In addition, we also employed a high-speed camera to obtain the bubble size distribution and bubble shape in a dilute suspension. A rapid decrease in bubble velocity for a dilute bubble suspension is attributed to the effects of bubble-wall collisions. The more gradual decrease of bubble velocity as gas volume fraction increases, due to subsequent hindering of bubble motion, is in qualitative agreement with the predictions of Spelt and Sangani for the effects of potential-flow bubble-bubble interactions on the mean velocity. The

  4. Bubble injected hydrocyclone flotation cell

    SciTech Connect

    Stanley, D.A.; Jordon, C.E.

    1990-11-20

    This patent describes an apparatus for selective separation of a mixture of hydrophobic and hydrophilic mineral particles. It comprises: a bubble-injected hydrocyclone flotation cell and a bubble slurry. The cell comprises an enclosed body section; a mineral pulp feed port; a bubble slurry feed port; and a vortex finder.

  5. The Early Years: Blowing Bubbles

    ERIC Educational Resources Information Center

    Ashbrook, Peggy

    2016-01-01

    Blowing bubbles is not only a favorite summer activity for young children. Studying bubbles that are grouped together, or "foam," is fun for children and fascinating to many real-world scientists. Foam is widely used--from the bedroom (mattresses) to outer space (insulating panels on spacecraft). Bubble foam can provide children a…

  6. Cohesion of Bubbles in Foam

    ERIC Educational Resources Information Center

    Ross, Sydney

    1978-01-01

    The free-energy change, or binding energy, of an idealized bubble cluster is calculated on the basis of one mole of gas, and on the basis of a single bubble going from sphere to polyhedron. Some new relations of bubble geometry are developed in the course of the calculation. (BB)

  7. Trauma research in Qatar: a literature review and discussion of progress after establishment of a trauma research centre.

    PubMed

    El-Menyar, A; Asim, M; Zarour, A; Abdelrahman, H; Peralta, R; Parchani, A; Al-Thani, H

    2016-02-01

    A structured research programme is one of the main pillars of a trauma care system. Despite the high rate of injury-related mortalities, especially road traffic accidents, in Qatar, little consideration has been given to research in trauma. This review aimed to analyse research publications on the subject of trauma published from Qatar and to discuss the progress of clinical research in Qatar and the Gulf Cooperation Council countries with special emphasis on trauma research. A literature search using PubMed and Google Scholar search engines located 757 English-language articles within the fields of internal medicine, surgery and trauma originating from Qatar between the years 1993 and 2013. A steep increase in the number of trauma publications since 2010 could be linked to the setting up of a trauma research centre in Qatar in 2011. We believe that establishing a research unit has made a major impact on research productivity, which ultimately benefits health care.

  8. The Liberal Arts Bubble

    ERIC Educational Resources Information Center

    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…

  9. Ocular trauma in otolaryngology.

    PubMed

    Govett, G S; Amedee, R G

    1992-05-01

    Otolaryngologists are commonly called upon to emergently evaluate blunt trauma to the facial skeleton. These injuries are occasionally associated with serious trauma to the orbital contents. This manuscript reviews these orbital injuries by considering the pertinent eye anatomy and the extensive examination usually performed by an ophthalmologist. Anterior and posterior segment injuries along with specific trauma to the optic nerve will also be discussed.

  10. Trauma Facts for Educators

    ERIC Educational Resources Information Center

    National Child Traumatic Stress Network, 2008

    2008-01-01

    This paper offers facts which can help educators deal with children undergoing trauma. These include: (1) One out of every 4 children attending school has been exposed to a traumatic event that can affect learning and/or behavior; (2) Trauma can impact school performance; (3) Trauma can impair learning; (4) Traumatized children may experience…

  11. Military Sexual Trauma

    MedlinePlus

    Military Sexual Trauma What is military sexual trauma (MST)? Military sexual trauma, or MST, is the term used by VA to refer to experiences of sexual assault ... that a Veteran experienced during his or her military service. The definition used by the VA comes ...

  12. Helping Youth Overcome Trauma

    ERIC Educational Resources Information Center

    Chambers, Jamie C.

    2005-01-01

    The effects of trauma can roll on unchecked like a spirit of death. In its path are strewn its once vibrant victims. Human bonds are rent asunder by the disgrace of trauma. These are the youngsters who have been verbally bashed, physically battered, sexually assaulted, and spiritually exploited. Other traumas of childhood neglect include: (1)…

  13. Bubbly Little Star

    NASA Technical Reports Server (NTRS)

    2007-01-01

    In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.

    The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.

    These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

    Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.

    This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

    This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

  14. Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles

    NASA Technical Reports Server (NTRS)

    Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

    2006-01-01

    The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

  15. Bubble dynamics and bubble-induced turbulence of a single-bubble chain

    NASA Astrophysics Data System (ADS)

    Lee, Joohyoung; Park, Hyungmin

    2016-11-01

    In the present study, the bubble dynamics and liquid-phase turbulence induced by a chain of bubbles injected from a single nozzle have been experimentally investigated. Using a high-speed two-phase particle image velociemtry, measurements on the bubbles and liquid-phase velocity field are conducted in a transparent tank filled with water, while varying the bubble release frequency from 0.1 to 35 Hz. The tested bubble size ranges between 2.0-3.2 mm, and the corresponding bubble Reynolds number is 590-1100, indicating that it belongs to the regime of path instability. As the release frequency increases, it is found that the global shape of bubble dispersion can be classified into two regimes: from asymmetric (regular) to axisymmetric (irregular). In particular, at higher frequency, the wake vortices of leading bubbles cause an irregular behaviour of the following bubble. For the liquid phase, it is found that a specific trend on the bubble-induced turbulence appears in a strong relation to the above bubble dynamics. Considering this, we try to provide a theoretical model to estimate the liquid-phase turbulence induced by a chain of bubbles. Supported by a Grant funded by Samsung Electronics, Korea.

  16. Signature of anisotropic bubble collisions

    SciTech Connect

    Salem, Michael P.

    2010-09-15

    Our universe may have formed via bubble nucleation in an eternally inflating background. Furthermore, the background may have a compact dimension--the modulus of which tunnels out of a metastable minimum during bubble nucleation--which subsequently grows to become one of our three large spatial dimensions. When in this scenario our bubble universe collides with other ones like it, the collision geometry is constrained by the reduced symmetry of the tunneling instanton. While the regions affected by such bubble collisions still appear (to leading order) as disks in an observer's sky, the centers of these disks all lie on a single great circle, providing a distinct signature of anisotropic bubble nucleation.

  17. Ring Bubbles of Dolphins

    NASA Technical Reports Server (NTRS)

    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. Trauma system development.

    PubMed

    Lendrum, R A; Lockey, D J

    2013-01-01

    The word 'trauma' describes the disease entity resulting from physical injury. Trauma is one of the leading causes of death worldwide and deaths due to injury look set to increase. As early as the 1970s, it became evident that centralisation of resources and expertise could reduce the mortality rate from serious injury and that organisation of trauma care delivery into formal systems could improve outcome further. Internationally, trauma systems have evolved in various forms, with widespread reports of mortality and functional outcome benefits when major trauma management is delivered in this way. The management of major trauma in England is currently undergoing significant change. The London Trauma System began operating in April 2010 and others throughout England became operational this year. Similar systems exist internationally and continue to be developed. Anaesthetists have been and continue to be involved with all levels of trauma care delivery, from the provision of pre-hospital trauma and retrieval teams, through to chronic pain management and rehabilitation of patients back into society. This review examines the international development of major trauma care delivery and the components of a modern trauma system.

  19. Numerical simulation of increasing initial perturbations of a bubble in the bubble-shock interaction problem

    NASA Astrophysics Data System (ADS)

    Korneev, Boris; Levchenko, Vadim

    2016-12-01

    A set of numerical experiments on the interaction between a planar shock wave and a spherical bubble with a slightly perturbed surface is considered. Spectral analysis of the instability growth is carried out and three-dimensional Euler equations of fluid dynamics are chosen as the mathematical model for the process. The equations are solved via the Runge-Kutta discontinuous Galerkin method and the special DiamondTorre algorithm for multi-GPU implementation is used.

  20. Bubble dynamics in drinks

    NASA Astrophysics Data System (ADS)

    Broučková, Zuzana; Trávníček, Zdeněk; Šafařík, Pavel

    2014-03-01

    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.

  1. Slurry bubble column hydrodynamics

    NASA Astrophysics Data System (ADS)

    Rados, Novica

    Slurry bubble column reactors are presently used for a wide range of reactions in both chemical and biochemical industry. The successful design and scale up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, heat and mass transport characteristics. The primary objective of this thesis is to improve presently limited understanding of the gas-liquid-solid slurry bubble column hydrodynamics. The effect of superficial gas velocity (8 to 45 cm/s), pressure (0.1 to 1.0 MPa) and solids loading (20 and 35 wt.%) on the time-averaged solids velocity and turbulent parameter profiles has been studied using Computer Automated Radioactive Particle Tracking (CARPT). To accomplish this, CARPT technique has been significantly improved for the measurements in highly attenuating systems, such as high pressure, high solids loading stainless steel slurry bubble column. At a similar set of operational conditions time-averaged gas and solids holdup profiles have been evaluated using the developed Computed Tomography (CT)/Overall gas holdup procedure. This procedure is based on the combination of the CT scans and the overall gas holdup measurements. The procedure assumes constant solids loading in the radial direction and axially invariant cross-sectionally averaged gas holdup. The obtained experimental holdup, velocity and turbulent parameters data are correlated and compared with the existing low superficial gas velocities and atmospheric pressure CARPT/CT gas-liquid and gas-liquid-solid slurry data. The obtained solids axial velocity radial profiles are compared with the predictions of the one dimensional (1-D) liquid/slurry recirculation phenomenological model. The obtained solids loading axial profiles are compared with the predictions of the Sedimentation and Dispersion Model (SDM). The overall gas holdup values, gas holdup radial profiles, solids loading axial profiles, solids axial velocity radial profiles and solids

  2. Sonoluminescence, sonochemistry and bubble dynamics of single bubble cavitation

    NASA Astrophysics Data System (ADS)

    Hatanaka, Shin-ichi

    2012-09-01

    The amount of hydroxyl radicals produced from a single cavitation bubble was quantified by terephthalate dosimetry at various frequencies and pressure amplitudes, while the dynamics of the single bubble was observed by stroboscopic and light-scattering methods. Also, sonoluminescence (SL), sonochemiluminescence (SCL) of luminol, and sodium atom emission (Na*) in the cavitation field were observed. The amount of hydroxyl radicals per cycle as well as the intensity of SL was proportional to pressure amplitude at every frequency performed, and it decreased with increasing frequency. When the single bubble was dancing with a decrease in pressure amplitude, however, the amount of hydroxyl radicals was greater than that for the stable bubble at the higher pressure amplitude and did not significantly decrease with frequency. Furthermore, SCL and Na* were detected only under unstable bubble conditions. These results imply that the instability of bubbles significantly enhances sonochemical efficiency for non-volatile substances in liquid phase.

  3. Bubble colloidal AFM probes formed from ultrasonically generated bubbles.

    PubMed

    Vakarelski, Ivan U; Lee, Judy; Dagastine, Raymond R; Chan, Derek Y C; Stevens, Geoffrey W; Grieser, Franz

    2008-02-05

    Here we introduce a simple and effective experimental approach to measuring the interaction forces between two small bubbles (approximately 80-140 microm) in aqueous solution during controlled collisions on the scale of micrometers to nanometers. The colloidal probe technique using atomic force microscopy (AFM) was extended to measure interaction forces between a cantilever-attached bubble and surface-attached bubbles of various sizes. By using an ultrasonic source, we generated numerous small bubbles on a mildly hydrophobic surface of a glass slide. A single bubble picked up with a strongly hydrophobized V-shaped cantilever was used as the colloidal probe. Sample force measurements were used to evaluate the pure water bubble cleanliness and the general consistency of the measurements.

  4. Instability of two rising bubbles

    NASA Astrophysics Data System (ADS)

    Galper, Alexander; Miloh, Touvia

    1999-11-01

    We consider the stability of two rising ideal gas spherical bubbles subject of an intrinsic dynamics. The dynamics is prescribed or governed by the Rayleigh-Plesset equation adjusted for the pressure field induced by the other bubble in the center of each. Hence, each bubble exhibits linear (nonlinear) oscillations about a stable equilibrium. In order to treat the Liapunov stability problem of bubbles spatial motion we develop the corresponding Hamiltonian formalism. Thus, we find that the oscillations can stabilize the side-by-side and one-below-the-other bubbles translation. These types of translation are known to be asymptotically stable (unstable) for the motion of a pair of purely spherical rigid bubbles. The stabilization phenomenon depends on the frequency and phase difference in the bubbles fast oscillations. The ``rigid'' bubbles theory of the motion is known to have certain discrepancies with the relevant experiments. In order to remove them it is proposed to account for the vorticity wake behind each bubble. Nevertheless, we are able to explain the experiments remaining within the potential framework. Finally, we consider the case of chaotic pulsations. The motion of the two bubbles can also inherit a chaotic character. It results, in turn, in a certain strange attractor for the spatial motion of a pair.

  5. Rectified growth of histotripsy bubbles

    PubMed Central

    Kreider, Wayne; Maxwell, Adam D.; Khokhlova, Tatiana; Simon, Julianna C.; Khokhlova, Vera A.; Sapozhnikov, Oleg; Bailey, Michael R.

    2015-01-01

    Histotripsy treatments use high-amplitude shock waves to fractionate tissue. Such treatments have been demonstrated using both cavitation bubbles excited with microsecond-long pulses and boiling bubbles excited for milliseconds. A common feature of both approaches is the need for bubble growth, where at 1 MHz cavitation bubbles reach maximum radii on the order of 100 microns and boiling bubbles grow to about 1 mm. To explore how histotripsy bubbles grow, a model of a single, spherical bubble that accounts for heat and mass transport was used to simulate the bubble dynamics. Results suggest that the asymmetry inherent in nonlinearly distorted waveforms can lead to rectified bubble growth, which is enhanced at elevated temperatures. Moreover, the rate of this growth is sensitive to the waveform shape, in particular the transition from the peak negative pressure to the shock front. Current efforts are focused on elucidating this behavior by obtaining an improved calibration of measured histotripsy waveforms with a fiber-optic hydrophone, using a nonlinear propagation model to assess the impact on the focal waveform of higher harmonics present at the source’s surface, and photographically observing bubble growth rates. PMID:26413193

  6. Self-organization of hydrogen gas bubbles rising above laser-etched metallic aluminum in a weakly basic aqueous solution.

    PubMed

    Barmina, E V; Kuzmin, P G; Shafeev, G A

    2011-10-01

    Self-organization of hydrogen bubbles is reported under etching of metallic Aluminum in a weakly basic solution. The ascending gas bubbles drift to the areas with higher density of bubbles. As a result, ascending bubbles form various stationary structures whose symmetry is determined by the symmetry of the etched area. Bubbles are aligned along the bisectors of the contour of the etched area. The special laser-assisted profiling of the etched area in shape of a vortex induces a torque in the fluid above the etched area. The process is interpreted on the basis of Bernoulli equation.

  7. In Search of the Big Bubble

    ERIC Educational Resources Information Center

    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…

  8. Collapse of large vapor bubbles

    NASA Technical Reports Server (NTRS)

    Tegart, J.; Dominick, S.

    1982-01-01

    The refilling of propellant tanks while in a low-gravity environment requires that entrapped vapor bubbles be collapsed by increasing the system pressure. Tests were performed to verify the mechanism of collapse for these large vapor bubbles with the thermodynamic conditions, geometry, and boundary conditions being those applicable to propellant storage systems. For these conditions it was found that conduction heat transfer determined the collapse rate, with the specific bubble geometry having a significant influence.

  9. Neutron detection via bubble chambers.

    PubMed

    Jordan, D V; Ely, J H; Peurrung, A J; Bond, L J; Collar, J I; Flake, M; Knopf, M A; Pitts, W K; Shaver, M; Sonnenschein, A; Smart, J E; Todd, L C

    2005-01-01

    Research investigating the application of pressure-cycled bubble chambers to fast neutron detection is described. Experiments with a Halon-filled chamber showed clear sensitivity to an AmBe neutron source and insensitivity to a (137)Cs gamma source. Bubble formation was documented using high-speed photography, and a ceramic piezo-electric transducer element registered the acoustic signature of bubble formation. In a second set of experiments, the bubble nucleation response of a Freon-134a chamber to an AmBe neutron source was documented with high-speed photography.

  10. Helium bubble bursting in tungsten

    SciTech Connect

    Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.

    2013-12-28

    Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz.

  11. Droplets, Bubbles and Ultrasound Interactions.

    PubMed

    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.

  12. Bubble measuring instrument and method

    NASA Technical Reports Server (NTRS)

    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.

  13. Bubble Measuring Instrument and Method

    NASA Technical Reports Server (NTRS)

    Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)

    2002-01-01

    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.

  14. About Military Sexual Trauma

    MedlinePlus Videos and Cool Tools

    ... out why Close About Military Sexual Trauma Veterans Health Administration Loading... Unsubscribe from Veterans Health Administration? Cancel Unsubscribe Working... Subscribe Subscribed Unsubscribe 12, ...

  15. Bubble Size Distribution in a Vibrating Bubble Column

    NASA Astrophysics Data System (ADS)

    Mohagheghian, Shahrouz; Wilson, Trevor; Valenzuela, Bret; Hinds, Tyler; Moseni, Kevin; Elbing, Brian

    2016-11-01

    While vibrating bubble columns have increased the mass transfer between phases, a universal scaling law remains elusive. Attempts to predict mass transfer rates in large industrial scale applications by extrapolating laboratory scale models have failed. In a stationary bubble column, mass transfer is a function of phase interfacial area (PIA), while PIA is determined based on the bubble size distribution (BSD). On the other hand, BSD is influenced by the injection characteristics and liquid phase dynamics and properties. Vibration modifies the BSD by impacting the gas and gas-liquid dynamics. This work uses a vibrating cylindrical bubble column to investigate the effect of gas injection and vibration characteristics on the BSD. The bubble column has a 10 cm diameter and was filled with water to a depth of 90 cm above the tip of the orifice tube injector. BSD was measured using high-speed imaging to determine the projected area of individual bubbles, which the nominal bubble diameter was then calculated assuming spherical bubbles. The BSD dependence on the distance from the injector, injector design (1.6 and 0.8 mm ID), air flow rates (0.5 to 5 lit/min), and vibration conditions (stationary and vibration conditions varying amplitude and frequency) will be presented. In addition to mean data, higher order statistics will also be provided.

  16. Visualization of airflow growing soap bubbles

    NASA Astrophysics Data System (ADS)

    Al Rahbi, Hamood; Bock, Matthew; Ryu, Sangjin

    2016-11-01

    Visualizing airflow inside growing soap bubbles can answer questions regarding the fluid dynamics of soap bubble blowing, which is a model system for flows with a gas-liquid-gas interface. Also, understanding the soap bubble blowing process is practical because it can contribute to controlling industrial processes similar to soap bubble blowing. In this study, we visualized airflow which grows soap bubbles using the smoke wire technique to understand how airflow blows soap bubbles. The soap bubble blower setup was built to mimic the human blowing process of soap bubbles, which consists of a blower, a nozzle and a bubble ring. The smoke wire was placed between the nozzle and the bubble ring, and smoke-visualized airflow was captured using a high speed camera. Our visualization shows how air jet flows into the growing soap bubble on the ring and how the airflow interacts with the soap film of growing bubble.

  17. Stable tridimensional bubble clusters in multi-bubble sonoluminescence (MBSL).

    PubMed

    Rosselló, J M; Dellavale, D; Bonetto, F J

    2015-01-01

    In the present work, stable clusters made of multiple sonoluminescent bubbles are experimentally and theoretically studied. Argon bubbles were acoustically generated and trapped using bi-frequency driving within a cylindrical chamber filled with a sulfuric acid aqueous solution (SA85w/w). The intensity of the acoustic pressure field was strong enough to sustain, during several minutes, a large number of positionally and spatially fixed (without pseudo-orbits) sonoluminescent bubbles over an ellipsoidally-shaped tridimensional array. The dimensions of the ellipsoids were studied as a function of the amplitude of the applied low-frequency acoustic pressure (PAc(LF)) and the static pressure in the fluid (P0). In order to explain the size and shape of the bubble clusters, we performed a series of numerical simulations of the hydrodynamic forces acting over the bubbles. In both cases the observed experimental behavior was in excellent agreement with the numerical results. The simulations revealed that the positionally stable region, mainly determined by the null primary Bjerknes force (F→Bj), is defined as the outer perimeter of an axisymmetric ellipsoidal cluster centered in the acoustic field antinode. The role of the high-frequency component of the pressure field and the influence of the secondary Bjerknes force are discussed. We also investigate the effect of a change in the concentration of dissolved gas on the positional and spatial instabilities through the cluster dimensions. The experimental and numerical results presented in this paper are potentially useful for further understanding and modeling numerous current research topics regarding multi-bubble phenomena, e.g. forces acting on the bubbles in multi-frequency acoustic fields, transient acoustic cavitation, bubble interactions, structure formation processes, atomic and molecular emissions of equal bubbles and nonlinear or unsteady acoustic pressure fields in bubbly media.

  18. Ultrasound in trauma.

    PubMed

    Rippey, James C R; Royse, Alistair G

    2009-09-01

    Point-of-care ultrasound is well suited for use in the emergency setting for assessment of the trauma patient. Currently, portable ultrasound machines with high-resolution imaging capability allow trauma patients to be imaged in the pre-hospital setting, emergency departments and operating theatres. In major trauma, ultrasound is used to diagnose life-threatening conditions and to prioritise and guide appropriate interventions. Assessment of the basic haemodynamic state is a very important part of ultrasound use in trauma, but is discussed in more detail elsewhere. Focussed assessment with sonography for Trauma (FAST) rapidly assesses for haemoperitoneum and haemopericardium, and the Extended FAST examination (EFAST) explores for haemothorax, pneumothorax and intravascular filling status. In regional trauma, ultrasound can be used to detect fractures, many vascular injuries, musculoskeletal injuries, testicular injuries and can assess foetal viability in pregnant trauma patients. Ultrasound can also be used at the bedside to guide procedures in trauma, including nerve blocks and vascular access. Importantly, these examinations are being performed by the treating physician in real time, allowing for immediate changes to management of the patient. Controversy remains in determining the best training to ensure competence in this user-dependent imaging modality.

  19. Thromboprophylaxis for trauma patients

    PubMed Central

    Lozano, Luis Manuel Barrera; Perel, Pablo; Ker, Katharine; Cirocchi, Roberto; Farinella, Eriberto; Morales, Carlos Hernando

    2014-01-01

    This is the protocol for a review and there is no abstract. The objectives are as follows: To assess the effects of thromboprophylaxis in trauma patients on mortality and incidence of DVT and PE. To compare the effects of different thromboprophylaxis interventions and their relative effects according to the type of trauma. PMID:25267908

  20. Treating childhood trauma.

    PubMed

    Terr, Lenore C

    2013-01-01

    This review begins with the question "What is childhood trauma?" Diagnosis is discussed next, and then the article focuses on treatment, using 3 basic principles-abreaction, context, and correction. Treatment modalities and complications are discussed, with case vignettes presented throughout to illustrate. Suggestions are provided for the psychiatrist to manage countertransference as trauma therapy proceeds.

  1. Children and Facial Trauma

    MedlinePlus

    ... up after Facial trauma: A prospective study. Otolaryngol Head Neck Surg 1997: 117:72-75 Kim MK, Buchman ... trauma in children: An urban hospital’s experience. Otolaryngoly–Head Neck Surgery 2000: 123: 439-43 Patient Health Home ...

  2. Advances in forefoot trauma.

    PubMed

    Clements, J Randolph; Schopf, Robert

    2013-07-01

    Forefoot traumas, particularly involving the metatarsals, are commonly occurring injuries. There have been several advances in management of these injuries. These advances include updates in operative technique, internal fixation options, plating constructs, and external fixation. In addition, the advances of soft tissue management have improved outcomes. This article outlines these injuries and provides an update on techniques, principles, and understanding of managing forefoot trauma.

  3. Bubble formation in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1996-01-01

    An extensive experimental program was initiated for the purpose of understanding the mechanisms leading to bubble generation during fluid handling procedures in a microgravity environment. Several key fluid handling procedures typical for PCG experiments were identified for analysis in that program. Experiments were designed to specifically understand how such procedures can lead to bubble formation. The experiments were then conducted aboard the NASA KC-135 aircraft which is capable of simulating a low gravity environment by executing a parabolic flight attitude. However, such a flight attitude can only provide a low gravity environment of approximately 10-2go for a maximum period of 30 seconds. Thus all of the tests conducted for these experiments were designed to last no longer than 20 seconds. Several experiments were designed to simulate some of the more relevant fluid handling procedures during protein crystal growth experiments. These include submerged liquid jet cavitation, filling of a cubical vessel, submerged surface scratch, attached drop growth, liquid jet impingement, and geysering experiments. To date, four separate KC-135 flight campaigns were undertaken specifically for performing these experiments. However, different experiments were performed on different flights.

  4. Bubble formation in microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    1994-01-01

    Two KC-135 flight campaigns have been conducted to date which are specifically dedicated to study bubble formation in microgravity. The first flight was conducted during March 14-18, 1994, and the other during June 20-24, 1994. The results from the June 1994 flight have not been analyzed yet, while the results from the March flight have been partially analyzed. In the first flight three different experiments were performed, one with the specific aim at determining whether or not cavitation can take place during any of the fluid handling procedures adopted in the shuttle bioprocessing experiments. The other experiments were concerned with duplicating some of the procedures that resulted in bubble formation, namely the NCS filling procedure and the needle scratch of a solid surface. The results from this set of experiments suggest that cavitation did not take place during any of the fluid handling procedures. The results clearly indicate that almost all were generated as a result of the breakup of the gas/liquid interface. This was convincingly demonstrated in the scratch tests as well as in the liquid fill tests.

  5. Triangular bubble spline surfaces

    PubMed Central

    Kapl, Mario; Byrtus, Marek; Jüttler, Bert

    2011-01-01

    We present a new method for generating a Gn-surface from a triangular network of compatible surface strips. The compatible surface strips are given by a network of polynomial curves with an associated implicitly defined surface, which fulfill certain compatibility conditions. Our construction is based on a new concept, called bubble patches, to represent the single surface patches. The compatible surface strips provide a simple Gn-condition between two neighboring bubble patches, which are used to construct surface patches, connected with Gn-continuity. For n≤2, we describe the obtained Gn-condition in detail. It can be generalized to any n≥3. The construction of a single surface patch is based on Gordon–Coons interpolation for triangles. Our method is a simple local construction scheme, which works uniformly for vertices of arbitrary valency. The resulting surface is a piecewise rational surface, which interpolates the given network of polynomial curves. Several examples of G0, G1 and G2-surfaces are presented, which have been generated by using our method. The obtained surfaces are visualized with reflection lines to demonstrate the order of smoothness. PMID:22267872

  6. Tuning bubbly structures in microchannels

    PubMed Central

    Vuong, Sharon M.; Anna, Shelley L.

    2012-01-01

    Foams have many useful applications that arise from the structure and size distribution of the bubbles within them. Microfluidics allows for the rapid formation of uniform bubbles, where bubble size and volume fraction are functions of the input gas pressure, liquid flow rate, and device geometry. After formation, the microchannel confines the bubbles and determines the resulting foam structure. Bubbly structures can vary from a single row (“dripping”), to multiple rows (“alternating”), to densely packed bubbles (“bamboo” and dry foams). We show that each configuration arises in a distinct region of the operating space defined by bubble volume and volume fraction. We describe the boundaries between these regions using geometric arguments and show that the boundaries are functions of the channel aspect ratio. We compare these geometric arguments with foam structures observed in experiments using flow-focusing, T-junction, and co-flow designs to generate stable nitrogen bubbles in aqueous surfactant solution and stable droplets in oil containing dissolved surfactant. The outcome of this work is a set of design parameters that can be used to achieve desired foam structures as a function of device geometry and experimental control parameters. PMID:22655008

  7. Bubble Transport through Micropillar Arrays

    NASA Astrophysics Data System (ADS)

    Lee, Kenneth; Savas, Omer

    2012-11-01

    In current energy research, artificial photosynthetic devices are being designed to split water and harvest hydrogen gas using energy from the sun. In one such design, hydrogen gas bubbles evolve on the catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system. Therefore, an efficient method of collecting the evolved gas bubbles is crucial. Preliminary flow visualization has been conducted of bubbles advecting through dense arrays of pillars. Bubbles moving through square and hexagonal arrays are tracked, and the results are qualitatively described. Initial attempts to correlate bubble motion with relevant lengthscales and forces are also presented. These observations suggest how bubble transport within such pillar arrays can be managed, as well as guide subsequent experiments that investigate bubble evolution and collection. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.

  8. Bubble detector investigations in China.

    PubMed

    Guo, Shi-Lun

    2006-01-01

    Investigation on bubble detectors started in China in 1989. Five types of bubble detectors have been developed, with LET thresholds ranging from 0.05 to 6.04 MeV mg(-1) cm(2) at 25 degrees C. The neutron response of bubble detectors made with freon-12 has been investigated with mono-energetic neutrons from 20 keV to 19 MeV. Its effective threshold energy for neutron detection is approximately 100 keV at 28 degrees C. The response above this threshold is approximately 1.5 x 10(-4) (bubble cm(-2))/(n cm(-2)). Bubble detectors are unique not only for neutron dosimetry but also for monitoring and identifying high-energy heavy ions such as cosmic radiation in the space. High-energy heavy ion tracks in large size bubble detectors have been investigated in cooperation with scientists in Japan. The key parameter behind the thresholds of bubble detectors for track registration is the critical rate of energy loss. Three approaches to identify high-energy heavy ions with bubble detectors are suggested.

  9. Cellular High-Energy Cavitation Trauma - Description of a Novel In Vitro Trauma Model in Three Different Cell Types.

    PubMed

    Cao, Yuli; Risling, Mårten; Malm, Elisabeth; Sondén, Anders; Bolling, Magnus Frödin; Sköld, Mattias K

    2016-01-01

    The mechanisms involved in traumatic brain injury have yet to be fully characterized. One mechanism that, especially in high-energy trauma, could be of importance is cavitation. Cavitation can be described as a process of vaporization, bubble generation, and bubble implosion as a result of a decrease and subsequent increase in pressure. Cavitation as an injury mechanism is difficult to visualize and model due to its short duration and limited spatial distribution. One strategy to analyze the cellular response of cavitation is to employ suitable in vitro models. The flyer-plate model is an in vitro high-energy trauma model that includes cavitation as a trauma mechanism. A copper fragment is accelerated by means of a laser, hits the bottom of a cell culture well causing cavitation, and shock waves inside the well and cell medium. We have found the flyer-plate model to be efficient, reproducible, and easy to control. In this study, we have used the model to analyze the cellular response to microcavitation in SH-SY5Y neuroblastoma, Caco-2, and C6 glioma cell lines. Mitotic activity in neuroblastoma and glioma was investigated with BrdU staining, and cell numbers were calculated using automated time-lapse imaging. We found variations between cell types and between different zones surrounding the lesion with these methods. It was also shown that the injured cell cultures released S-100B in a dose-dependent manner. Using gene expression microarray, a number of gene families of potential interest were found to be strongly, but differently regulated in neuroblastoma and glioma at 24 h post trauma. The data from the gene expression arrays may be used to identify new candidates for biomarkers in cavitation trauma. We conclude that our model is useful for studies of trauma in vitro and that it could be applied in future treatment studies.

  10. Blunt Force Trauma in Veterinary Forensic Pathology.

    PubMed

    Ressel, L; Hetzel, U; Ricci, E

    2016-09-01

    Veterinary pathologists commonly encounter lesions of blunt trauma. The development of lesions is affected by the object's mass, velocity, size, shape, and angle of impact and by the plasticity and mobility of the impacted organ. Scrape, impact, and pattern abrasions cause localized epidermal loss and sometimes broken hairs and implanted foreign material. Contusions are best identified after reflecting the skin, and must be differentiated from coagulopathies and livor mortis. Lacerations-traumatic tissue tears-may have irregular margins, bridging by more resilient tissue, deviation of the wound tail, crushed hairs, and unilateral abrasion. Hanging or choking can cause circumferential cervical abrasions, contusions and rupture of hairs, hyoid bone fractures, and congestion of the head. Other special forms of blunt trauma include fractured nails, pressure sores, and dog bites. Ocular blunt trauma causes extraocular and intraocular hemorrhages, proptosis, or retinal detachment. The thoracic viscera are relatively protected from blunt trauma but may develop hemorrhages in intercostal muscles, rib fractures, pulmonary or cardiac contusions or lacerations with subsequent hemothorax, pneumothorax, or cardiac arrhythmia. The abdominal wall is resilient and moveable, yet the liver and spleen are susceptible to traumatic laceration or rupture. Whereas extravasation of blood can occur after death, evidence of vital injury includes leukocyte infiltration, erythrophagocytosis, hemosiderin, reparative lesions of fibroblast proliferation, myocyte regeneration in muscle, and callus formation in bone. Understanding these processes aids in the diagnosis of blunt force trauma including estimation of the age of resulting injuries.

  11. Constrained Vapor Bubble

    NASA Technical Reports Server (NTRS)

    Huang, J.; Karthikeyan, M.; Plawsky, J.; Wayner, P. C., Jr.

    1999-01-01

    The nonisothermal Constrained Vapor Bubble, CVB, is being studied to enhance the understanding of passive systems controlled by interfacial phenomena. The study is multifaceted: 1) it is a basic scientific study in interfacial phenomena, fluid physics and thermodynamics; 2) it is a basic study in thermal transport; and 3) it is a study of a heat exchanger. The research is synergistic in that CVB research requires a microgravity environment and the space program needs thermal control systems like the CVB. Ground based studies are being done as a precursor to flight experiment. The results demonstrate that experimental techniques for the direct measurement of the fundamental operating parameters (temperature, pressure, and interfacial curvature fields) have been developed. Fluid flow and change-of-phase heat transfer are a function of the temperature field and the vapor bubble shape, which can be measured using an Image Analyzing Interferometer. The CVB for a microgravity environment, has various thin film regions that are of both basic and applied interest. Generically, a CVB is formed by underfilling an evacuated enclosure with a liquid. Classification depends on shape and Bond number. The specific CVB discussed herein was formed in a fused silica cell with inside dimensions of 3x3x40 mm and, therefore, can be viewed as a large version of a micro heat pipe. Since the dimensions are relatively large for a passive system, most of the liquid flow occurs under a small capillary pressure difference. Therefore, we can classify the discussed system as a low capillary pressure system. The studies discussed herein were done in a 1-g environment (Bond Number = 3.6) to obtain experience to design a microgravity experiment for a future NASA flight where low capillary pressure systems should prove more useful. The flight experiment is tentatively scheduled for the year 2000. The SCR was passed on September 16, 1997. The RDR is tentatively scheduled for October, 1998.

  12. Doughnut-shaped soap bubbles

    NASA Astrophysics Data System (ADS)

    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 =L3/6 π2 , and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V <α L3/6 π2 , with α ≈0.21 , such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble 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 <α L3/6 π2 cannot be stable and should not exist in foams, for instance.

  13. Study of a downward bubbly flow in a vertical pipe

    SciTech Connect

    Gorelik, R.S.; Kashinskii, O.N.; Nakoryakov, V.E.

    1987-07-01

    This paper reports on an experimental study of downward bubble-diffused concurrent flow in a vertical pipe. Two-phase flow was induced by introducing gas into a liquid with a special mixer which made it possible to obtain a gas-liquid flow with consistent bubble size. Visualization was performed by photography and flow rate was monitored by friction transducers. Shear stress and hydraulic conductivity were determined for various flow rates and Reynolds numbers. It was found that the stabilizing effect of the gas phase is determined by the fact that the flow rate pulsations introduced into the liquid flow have a negative sign; that the flow rate of the liquid near the bubbles, in other words, is lower than the mean flow rate of the liquid. This effect is not seen in ascending flows.

  14. Bubble Growth in Lunar Basalts

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2009-05-01

    Although Moon is usually said to be volatile-"free", lunar basalts are often vesicular with mm-size bubbles. The vesicular nature of the lunar basalts suggests that they contained some initial gas concentration. A recent publication estimated volatile concentrations in lunar basalts (Saal et al. 2008). This report investigates bubble growth on Moon and compares with that on Earth. Under conditions relevant to lunar basalts, bubble growth in a finite melt shell (i.e., growth of multiple regularly-spaced bubbles) is calculated following Proussevitch and Sahagian (1998) and Liu and Zhang (2000). Initial H2O content of 700 ppm (Saal et al. 2008) or lower is used and the effect of other volatiles (such as carbon dioxide, halogens, and sulfur) is ignored. H2O solubility at low pressures (Liu et al. 2005), concentration-dependent diffusivity in basalt (Zhang and Stolper 1991), and lunar basalt viscosity (Murase and McBirney 1970) are used. Because lunar atmospheric pressure is essentially zero, the confining pressure on bubbles is completely supplied by the overlying magma. Due to low H2O content in lunar basaltic melt (700 ppm H2O corresponds to a saturation pressure of 75 kPa), H2O bubbles only grow in the upper 16 m of a basalt flow or lake. A depth of 20 mm corresponds to a confining pressure of 100 Pa. Hence, vesicular lunar rocks come from very shallow depth. Some findings from the modeling are as follows. (a) Due to low confining pressure as well as low viscosity, even though volatile concentration is very low, bubble growth rate is extremely high, much higher than typical bubble growth rates in terrestrial melts. Hence, mm-size bubbles in lunar basalts are not strange. (b) Because the pertinent pressures are so low, bubble pressure due to surface tension plays a main role in lunar bubble growth, contrary to terrestrial cases. (c) Time scale to reach equilibrium bubble size increases as the confining pressure increases. References: (1) Liu Y, Zhang YX (2000) Earth

  15. Partial coalescence of soap bubbles

    NASA Astrophysics Data System (ADS)

    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.

  16. Terminating marine methane bubbles by superhydrophobic sponges.

    PubMed

    Chen, Xiao; Wu, Yuchen; Su, Bin; Wang, Jingming; Song, Yanlin; Jiang, Lei

    2012-11-14

    Marine methane bubbles are absorbed, steadily stored, and continuously transported based on the employment of superhydrophobic sponges. Antiwetting sponges are water-repellent in the atmosphere and absorb gas bubbles under water. Their capacity to store methane bubbles increases with enhanced submerged depth. Significantly, trapped methane bubbles can be continuously transported driven by differential pressure.

  17. Bubble Dynamics and Resulting Noise from Traveling Bubble Cavitation.

    DTIC Science & Technology

    1982-04-13

    has resulted in models which aqree well with bubble dynamics recorded by high speed film . Chahine, et. al. (23) incorporated asymmetric bubble...recording on the tape soundtrack . 3.8 Measurement of Gas Nuclei in Water The role of nuclei density and size in cavitation inception has been the subject...interference between the coherent background and the particle-diffracted radiation exooses photographic film in the far-field of the nuclei. This

  18. Blind Deconvolution on Underwater Images for Gas Bubble Measurement

    NASA Astrophysics Data System (ADS)

    Zelenka, C.; Koch, R.

    2015-04-01

    Marine gas seeps, such as in the Panarea area near Sicily (McGinnis et al., 2011), emit large amounts of methane and carbon-dioxide, greenhouse gases. Better understanding their impact on the climate and the marine environment requires precise measurements of the gas flux. Camera based bubble measurement systems suffer from defocus blur caused by a combination of small depth of field, insufficient lighting and from motion blur due to rapid bubble movement. These adverse conditions are typical for open sea underwater bubble images. As a consequence so called 'bubble boxes' have been built, which use elaborate setups, specialized cameras and high power illumination. A typical value of light power used is 1000W (Leifer et al., 2003). In this paper we propose the compensation of defocus and motion blur in underwater images by using blind deconvolution techniques. The quality of the images can be greatly improved, which will relax requirements on bubble boxes, reduce their energy consumption and widen their usability.

  19. The Dynamics of Vapor Bubbles in Acoustic Pressure Fields

    NASA Technical Reports Server (NTRS)

    Hao, Y.; Prosperetti, A.

    1999-01-01

    In spite of a superficial similarity with gas bubbles, the intimate coupling between dynamical and thermal processes confers to oscillating vapor bubbles some unique characteristics. This paper examines numerically the validity of some asymptotic-theory predictions such as the existence of two resonant radii and a limit size for a given sound amplitude and frequency. It is found that a small vapor bubble in a sound field of sufficient amplitude grows quickly through resonance and continues to grow thereafter at a very slow rate, seemingly indefinitely. Resonance phenomena therefore play a role for a few cycles at most, and reaching a limit size-if one exists at all-is found to require far more than several tens of thousands of cycles. It is also found that some small bubbles may grow or collapse depending on the phase of the sound field. The model accounts in detail for the thermo-fluid-mechanic processes in the vapor. In the second part of the paper, an approximate formulation valid for bubbles small with respect to the thermal penetration length in the vapor is derived and its accuracy examined, The present findings have implications for acoustically enhanced boiling heat transfer and other special applications such as boiling in microgravity.

  20. [Pediatric multiple trauma].

    PubMed

    Auner, B; Marzi, I

    2014-05-01

    Multiple trauma in children is rare so that even large trauma centers will only treat a small number of cases. Nevertheless, accidents are the most common cause of death in childhood whereby the causes are mostly traffic accidents and falls. Head trauma is the most common form of injury and the degree of severity is mostly decisive for the prognosis. Knowledge on possible causes of injury and injury patterns as well as consideration of anatomical and physiological characteristics are of great importance for treatment. The differences compared to adults are greater the younger the child is. Decompression and stopping bleeding are the main priorities before surgical fracture stabilization. The treatment of a severely injured child should be carried out by an interdisciplinary team in an approved trauma center with expertise in pediatrics. An inadequate primary assessment involves a high risk of early mortality. On the other hand children have a better prognosis than adults with comparable injuries.

  1. Military Sexual Trauma

    MedlinePlus

    ... Budget, & Performance VA Center for Innovation (VACI) Agency Financial Report (AFR) Budget Submission Recovery Act Resources Business ... Depression Military Sexual Trauma PTSD Schizophrenia Substance Use Suicide Prevention I am a... Returning Veteran Veteran in ...

  2. Nuances in pediatric trauma.

    PubMed

    Kenefake, Mary Ella; Swarm, Matthew; Walthall, Jennifer

    2013-08-01

    Pediatric trauma evaluation mimics adult stabilization in that it is best accomplished with a focused and systematic approach. Attention to developmental differences, anatomic and physiologic nuances, and patterns of injury equip emergency physicians to stabilize and manage pediatric injury.

  3. Men and Sexual Trauma

    MedlinePlus

    ... are some symptoms related to sexual trauma in boys and men? Particularly when the assailant is a ... those who do not. Emotional Disorders Men and boys who have been sexually assaulted are more likely ...

  4. Aspherical bubble dynamics and oscillation times

    SciTech Connect

    Vogel, A.; Noack, J.; Chapyak, E.J.; Godwin, R.P.

    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.

  5. Thromboembolic Complications Following Trauma

    DTIC Science & Technology

    2009-12-01

    injury in blunt trauma.15,16 Of the 114 patients, 73 received either antiplatelet agents or anticoagulation , and none developed strokes. The remaining...41 patients were determined to have contraindications to anticoagu- lation and did not receive heparin or antiplatelet agents . Of these, 19 (46...continue to be exam- ined. As prohemostatic agents are being used more frequently in trauma, it is important to understand the natural history of

  6. Quality of trauma care and trauma registries.

    PubMed

    Pino Sánchez, F I; Ballesteros Sanz, M A; Cordero Lorenzana, L; Guerrero López, F

    2015-03-01

    Traumatic disease is a major public health concern. Monitoring the quality of services provided is essential for the maintenance and improvement thereof. Assessing and monitoring the quality of care in trauma patient through quality indicators would allow identifying opportunities for improvement whose implementation would improve outcomes in hospital mortality, functional outcomes and quality of life of survivors. Many quality indicators have been used in this condition, although very few ones have a solid level of scientific evidence to recommend their routine use. The information contained in the trauma registries, spread around the world in recent decades, is essential to know the current health care reality, identify opportunities for improvement and contribute to the clinical and epidemiological research.

  7. Hypothermia in trauma.

    PubMed

    Moffatt, Samuel Edwin

    2013-12-01

    Hypovolaemic shock that results through traumatically inflicted haemorrhage can have disastrous consequences for the victim. Initially the body can compensate for lost circulating volume, but as haemorrhage continues compensatory mechanisms fail and the patient's condition worsens significantly. Hypovolaemia results in the lethal triad, a combination of hypothermia, acidosis and coagulopathy, three factors that are interlinked and serve to worsen each other. The lethal triad is a form of vicious cycle, which unless broken will result in death. This report will focus on the role of hypothermia (a third of the lethal triad) in trauma, examining literature to assess how prehospital temperature control can impact on the trauma patient. Spontaneous hypothermia following trauma has severely deleterious consequences for the trauma victim; however, both active warming of patients and clinically induced hypothermia can produce particularly positive results and improve patient outcome. Possible coagulopathic side effects of clinically induced hypothermia may be corrected with topical haemostatic agents, with the benefits of an extended golden hour given by clinically induced hypothermia far outweighing these risks. Active warming of patients, to prevent spontaneous trauma induced hypothermia, is currently the only viable method currently available to improve patient outcome. This method is easy to implement requiring simple protocols and contributes significantly to interrupting the lethal triad. However, the future of trauma care appears to lie with clinically induced therapeutic hypothermia. This new treatment provides optimism that in the future the number of deaths resulting from catastrophic haemorrhaging may be significantly lessened.

  8. Noninvasive ventilation in trauma

    PubMed Central

    Karcz, Marcin K; Papadakos, Peter J

    2015-01-01

    Trauma patients are a diverse population with heterogeneous needs for ventilatory support. This requirement depends mainly on the severity of their ventilatory dysfunction, degree of deterioration in gaseous exchange, any associated injuries, and the individual feasibility of potentially using a noninvasive ventilation approach. Noninvasive ventilation may reduce the need to intubate patients with trauma-related hypoxemia. It is well-known that these patients are at increased risk to develop hypoxemic respiratory failure which may or may not be associated with hypercapnia. Hypoxemia in these patients is due to ventilation perfusion mismatching and right to left shunt because of lung contusion, atelectasis, an inability to clear secretions as well as pneumothorax and/or hemothorax, all of which are common in trauma patients. Noninvasive ventilation has been tried in these patients in order to avoid the complications related to endotracheal intubation, mainly ventilator-associated pneumonia. The potential usefulness of noninvasive ventilation in the ventilatory management of trauma patients, though reported in various studies, has not been sufficiently investigated on a large scale. According to the British Thoracic Society guidelines, the indications and efficacy of noninvasive ventilation treatment in respiratory distress induced by trauma have thus far been inconsistent and merely received a low grade recommendation. In this review paper, we analyse and compare the results of various studies in which noninvasive ventilation was applied and discuss the role and efficacy of this ventilator modality in trauma. PMID:25685722

  9. Transient bubbles, bublets and breakup

    NASA Astrophysics Data System (ADS)

    Keen, Giles; Blake, John

    1999-11-01

    The non-spherical nature of the collapse of bubbles has important ramifications in many practical situations such as ultrasonic cleaning, tanning of leather, and underwater explosions. In particular the high speed liquid jet that can thread a collapsing bubble is central to the functional performance. An impressive photographic record of a liquid jet was obtained by Crum using a bubble situated in the vicinity of a platform oscillating vertically at a frequency of 60 Hz. A boundary integral method is used to model this situation and is found to closely mimic some of the observations. However, a slight variation of parameters or a change in the phase of the driving frequency can lead to dramatically different bubble behaviour, a feature also observed by Crum.

  10. Partial coalescence of soap bubbles

    NASA Astrophysics Data System (ADS)

    Pucci, G.; Harris, D. M.; Bush, J. W. M.

    2015-06-01

    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 ["Simulations of surfactant effects on the dynamics of coalescing drops and bubbles," Phys. Fluids 27, 012103 (2015)] and to the coalescence cascade of droplets on a fluid bath.

  11. Driving bubbles out of glass

    NASA Technical Reports Server (NTRS)

    Mattox, D. M.

    1981-01-01

    Surface tension gradient in melt forces gas bubbles to surface, increasing glass strength and transparency. Conventional chemical and buoyant fining are extremely slow in viscous glasses, but tension gradient method moves 250 um bubbles as rapidly as 30 um/s. Heat required for high temperature part of melt is furnished by stationary electrical or natural-gas heater; induction and laser heating are also possible. Method has many applications in industry processes.

  12. Slowing down bubbles with sound

    NASA Astrophysics Data System (ADS)

    Poulain, Cedric; Dangla, Remie; Guinard, Marion

    2009-11-01

    We present experimental evidence that a bubble moving in a fluid in which a well-chosen acoustic noise is superimposed can be significantly slowed down even for moderate acoustic pressure. Through mean velocity measurements, we show that a condition for this effect to occur is for the acoustic noise spectrum to match or overlap the bubble's fundamental resonant mode. We render the bubble's oscillations and translational movements using high speed video. We show that radial oscillations (Rayleigh-Plesset type) have no effect on the mean velocity, while above a critical pressure, a parametric type instability (Faraday waves) is triggered and gives rise to nonlinear surface oscillations. We evidence that these surface waves are subharmonic and responsible for the bubble's drag increase. When the acoustic intensity is increased, Faraday modes interact and the strongly nonlinear oscillations behave randomly, leading to a random behavior of the bubble's trajectory and consequently to a higher slow down. Our observations may suggest new strategies for bubbly flow control, or two-phase microfluidic devices. It might also be applicable to other elastic objects, such as globules, cells or vesicles, for medical applications such as elasticity-based sorting.

  13. Temperature measurements in cavitation bubbles

    NASA Astrophysics Data System (ADS)

    Coutier-Delgosha, Olivier

    2016-11-01

    Cavitation is usually a nearly isothermal process in the liquid phase, but in some specific flow conditions like hot water or cryogenic fluids, significant temperature variations are detected. In addition, a large temperature increase happens inside the cavitation bubbles at the very end of their collapse, due to the fast compression of the gas at the bubble core, which is almost adiabatic. This process is of primary interest in various biomedical and pharmaceutical applications, where the mechanisms of bubble collapse plays a major role. To investigate the amplitude and the spatial distribution of these temperature variations inside and outside the cavitation bubbles, a system based on cold wires has been developed. They have been tested in a configuration of a single bubble obtained by submitting a small air bubble to a large amplitude pressure wave. Some promising results have been obtained after the initial validation tests. This work is funded by the Office of Naval Research Global under Grant N62909-16-1-2116, Dr. Salahuddin Ahmed & Ki-Han Kim program managers.

  14. Bubble baths: just splashing around?

    NASA Astrophysics Data System (ADS)

    Robinson, Wesley; Speirs, Nathan; Sharker, Saberul Islam; Hurd, Randy; Williams, Bj; Truscott, Tadd

    2016-11-01

    Soap Bubbles on the water surface would seem to be an intuitive means for splash suppression, but their presence appears to be a double edged sword. We present on the water entry of hydrophilic spheres where the liquid surface is augmented by the presence of a bubble layer, similar to a bubble bath. While the presence of a bubble layer can diminish splashing upon impact at low Weber numbers, it also induces cavity formation at speeds below the critical velocity. The formation of a cavity generally results in larger Worthington jets and thus, larger amounts of ejected liquid. Bubble layers induce cavity formation by wetting the sphere prior to liquid impact, causing them to form cavities similar to those created by hydrophobic spheres. Droplets present on a pre-wetted sphere disrupt the flow of the advancing liquid during entry, pushing it away from the impacting body to form an entrained air cavity. This phenomena was noted by Worthington with pre-wetted stone marbles, and suggests that the application of a bubble layer is generally ineffective as a means of splash suppression.

  15. Bubble-Pen Lithography.

    PubMed

    Lin, Linhan; Peng, Xiaolei; Mao, Zhangming; Li, Wei; Yogeesh, Maruthi N; Rajeeva, Bharath Bangalore; Perillo, Evan P; Dunn, Andrew K; Akinwande, Deji; Zheng, Yuebing

    2016-01-13

    Current lithography techniques, which employ photon, electron, or ion beams to induce chemical or physical reactions for micro/nano-fabrication, have remained challenging in patterning chemically synthesized colloidal particles, which are emerging as building blocks for functional devices. Herein, we develop a new technique - bubble-pen lithography (BPL) - to pattern colloidal particles on substrates using optically controlled microbubbles. Briefly, a single laser beam generates a microbubble at the interface of colloidal suspension and a plasmonic substrate via plasmon-enhanced photothermal effects. The microbubble captures and immobilizes the colloidal particles on the substrate through coordinated actions of Marangoni convection, surface tension, gas pressure, and substrate adhesion. Through directing the laser beam to move the microbubble, we create arbitrary single-particle patterns and particle assemblies with different resolutions and architectures. Furthermore, we have applied BPL to pattern CdSe/ZnS quantum dots on plasmonic substrates and polystyrene (PS) microparticles on two-dimensional (2D) atomic-layer materials. With the low-power operation, arbitrary patterning and applicability to general colloidal particles, BPL will find a wide range of applications in microelectronics, nanophotonics, and nanomedicine.

  16. Trauma in pregnancy.

    PubMed

    Brown, Haywood L

    2009-07-01

    Acute traumatic injury during pregnancy is a significant contributor to maternal and fetal morbidity and mortality in the United States. Motor vehicle accidents are the leading cause of injury-related maternal death, followed by violence and assault. Lack of seat belts or other restraints increases the risks of both maternal and fetal morbidity and mortality. The American College of Obstetricians and Gynecologists recommends proper seat belt use by all pregnant women and screening for domestic abuse. Maternal injury and death from physical abuse is prevalent, and in some communities, homicide is a major cause of pregnancy-associated maternal death. Blunt trauma most often occurs as a result of motor vehicle accidents, whereas penetrating trauma results from gunshots or stabbings. Blunt trauma to the abdomen increases the risk for placental abruption, and direct fetal injury is more likely with penetrating trauma. Management strategies in acute maternal trauma must focus on a thorough assessment of the mother. A coordinated team effort that includes the obstetrician is essential to ensure optimal maternal and fetal outcomes. Imaging studies should not be delayed because of concerns of fetal radiation exposure, because the risk is minimal with usual imaging procedures, especially in mid-to-late pregnancy. The obstetrician should serve in a consultative role if nonobstetric surgical care is required and must also be prepared to intervene on behalf of the mother and the fetus if trauma care is compromised by the pregnancy. Perimortem cesarean delivery should be considered early in the resuscitation of a pregnant trauma victim, especially when fetal viability is a concern. Once the mother is stabilized in the emergency setting, she should be transported for appropriate maternal and fetal observation until both mother and fetus are clear of danger. It is essential that the clinician and staff maintain thorough and accurate documentation and recording of the chronology of

  17. Toxicological screening in trauma

    PubMed Central

    Carrigan, T; Field, H; Illingworth, R; Gaffney, P; Hamer, D

    2000-01-01

    Objectives—To determine the prevalence and patterns of alcohol and drug use in patients with major trauma. Methods—Consecutive trauma patient enrolment, 24 hours a day, was envisaged with anonymised patient data on gender, age band, and mechanism of injury collected. The study group had surplus plasma quantitatively analysed for ethanol concentration, and urine samples were initially screened, via immunoassay, for opiates, cannabinoids, amphetamines, benzodiazepines, cocaine, and methadone. Confirmation and specification of individual positive results was then performed using thin layer or gas-liquid chromatography. Drugs of treatment given in the resuscitation room, if subsequently detected in the urine samples, were excluded from the final results. Results—There were 116 eligible trauma patients assessed and treated in the resuscitation room over a six month period, of which 93 (80%) were enrolled. Altogether 27% of this trauma population had plasma ethanol concentrations greater than 80 mg/dl. There was a significantly higher prevalence of alcohol intoxication in the group not involved in a road traffic accident (RTA) compared with the group who were involved in a RTA. Initial screening of urine for drugs revealed a prevalence of 51%. After 12 exclusions due to iatrogenic administration of opiates, the final confirmed prevalence was 35% in this trauma population. The individual drug prevalence was 13% for cannabinoids, 11% for codeine, 8% for morphine, 6% for amphetamine, 6% for benzodiazepines, 3% for cocaine, 1% for dihydrocodeine, and 1% for methadone. Conclusions—There is a notable prevalence of drug and alcohol use in this British accident and emergency trauma population. A significantly higher prevalence for alcohol intoxication was found in the non-RTA group compared with the RTA group. The patterns of drug usage detected reflect local influences and less cocaine use is seen compared with American studies. The association between alcohol, drugs

  18. Acoustical Emission from Bubbles and Dynamics of Bubbles and Bubble Clouds.

    DTIC Science & Technology

    1997-01-01

    distribution of bubble sizes from a breaking wave , that is immediately following on the entrainment and disintegration of a given volume of air? In the...experimental confirmation was found by later workers. A simple statistical model has been proposed for the initial bubble sizes from breaking waves ...which also has received experimental support. A direct method of calculating wave -generated ripples has been proposed, which accounts quantitatively

  19. FEASTING BLACK HOLE BLOWS BUBBLES

    NASA Technical Reports Server (NTRS)

    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

  20. Single-bubble sonoluminescence from hydrogen

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    1999-09-01

    Single-bubble sonoluminescence (SBSL) from a hydrogen bubble is studied theoretically based on a quasiadiabatic compression model of a bubble collapse. It is clarified that the maximum temperature in a hydrogen bubble in 20 °C water under conditions of SBSL is always about 6000 K due to the effect of chemical reactions inside the bubble. It is suggested that the light emission at such temperature is by the transition from the lowest stable triplet state of the H2 molecule to the repulsive state resulting from two normal atoms (H2*→2H+hν). It is shown that the number of hydrogen molecules inside the bubble remains almost constant in spite of the high temperature and pressure inside the bubble at the collapse. It is also shown that the addition of argon to a hydrogen bubble results in the higher maximum temperature inside the bubble.

  1. Experiments on the motion of gas bubbles in turbulence generated by an active grid

    NASA Astrophysics Data System (ADS)

    Poorte, R. E. G.; Biesheuvel, A.

    2002-06-01

    The random motion of nearly spherical bubbles in the turbulent flow behind a grid is studied experimentally. In quiescent water these bubbles rise at high Reynolds number. The turbulence is generated by an active grid of the design of Makita (1991), and can have turbulence Reynolds number R[lambda] of up to 200. Minor changes in the geometry of the grid and in its mode of operation improves the isotropy of the turbulence, compared with that reported by Makita (1991) and Mydlarski & Warhaft (1996). The trajectory of each bubble is measured with high spatial and temporal resolution with a specially developed technique that makes use of a position-sensitive detector. Bubble statistics such as the mean rise velocity and the root-mean-square velocity fluctuations are obtained by ensemble averaging over many identical bubbles. The resulting bubble mean rise velocity is significantly reduced (up to 35%) compared with the quiescent conditions. The vertical bubble velocity fluctuations are found to be non-Gaussian, whereas the horizontal displacements are Gaussian for all times. The diffusivity of bubbles is considerably less than that of fluid particles. These findings are qualitatively consistent with results obtained through theoretical analysis and numerical simulations by Spelt & Biesheuvel (1997).

  2. Epidemiology of severe trauma.

    PubMed

    Alberdi, F; García, I; Atutxa, L; Zabarte, M

    2014-12-01

    Major injury is the sixth leading cause of death worldwide. Among those under 35 years of age, it is the leading cause of death and disability. Traffic accidents alone are the main cause, fundamentally in low- and middle-income countries. Patients over 65 years of age are an increasingly affected group. For similar levels of injury, these patients have twice the mortality rate of young individuals, due to the existence of important comorbidities and associated treatments, and are more likely to die of medical complications late during hospital admission. No worldwide, standardized definitions exist for documenting, reporting and comparing data on severely injured trauma patients. The most common trauma scores are the Abbreviated Injury Scale (AIS), the Injury Severity Score (ISS) and the Trauma and Injury severity Score (TRISS). Documenting the burden of injury also requires evaluation of the impact of post-trauma impairments, disabilities and handicaps. Trauma epidemiology helps define health service and research priorities, contributes to identify disadvantaged groups, and also facilitates the elaboration of comparable measures for outcome predictions.

  3. Bubble nucleation in an explosive micro-bubble actuator

    NASA Astrophysics Data System (ADS)

    van den Broek, D. M.; Elwenspoek, M.

    2008-06-01

    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 impulse. In this paper we take a closer look at the bubble nucleation. The moment of bubble nucleation was determined by both stroboscopic imaging and resistance thermometry. Two nucleation regimes could be distinguished. Several different heater designs were investigated under heat fluxes of hundreds of W mm-2. A close correspondence between current density in the heater and point of nucleation was found. This results in design rules for effective heaters.

  4. Single-Bubble and Multibubble Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    1999-11-01

    Computer simulations of radiation processes in an air bubble and an argon bubble are performed under a condition of single-bubble sonoluminescence (SBSL) based on a quasiadiabatic compression model of a bubble collapse. It is clarified that emissions from excited molecules are strongly quenched by high pressure and temperature inside a SBSL bubble and SBSL originates in the emissions from plasma. It is pointed out that sonoluminescence from cavitation fields (MBSL) originates in emissions from excited molecules, which is not quenched due to the much lower pressure and temperature inside the MBSL bubbles.

  5. Ultrasonic bubbles in medicine: influence of the shell.

    PubMed

    Postema, Michiel; Schmitz, Georg

    2007-04-01

    Ultrasound contrast agents consist of microscopically small bubbles encapsulated by an elastic shell. These microbubbles oscillate upon ultrasound insonification, and demonstrate highly nonlinear behavior, ameliorating their detectability. (Potential) medical applications involving the ultrasonic disruption of contrast agent microbubble shells include release-burst imaging, localized drug delivery, and noninvasive blood pressure measurement. To develop and enhance these techniques, predicting the cracking behavior of ultrasound-insonified encapsulated microbubbles has been of importance. In this paper, we explore microbubble behavior in an ultrasound field, with special attention to the influence of the bubble shell. A bubble in a sound field can be considered a forced damped harmonic oscillator. For encapsulated microbubbles, the presence of a shell has to be taken into account. In models, an extra damping parameter and a shell stiffness parameter have been included, assuming that Hooke's Law holds for the bubble shell. At high acoustic amplitudes, disruptive phenomena have been observed, such as microbubble fragmentation and ultrasonic cracking. We analyzed the occurrence of ultrasound contrast agent fragmentation, by simulating the oscillating behavior of encapsulated microbubbles with various sizes in a harmonic acoustic field. Fragmentation occurs exclusively during the collapse phase and occurs if the kinetic energy of the collapsing microbubble is greater than the instantaneous bubble surface energy, provided that surface instabilities have grown big enough to allow for break-up. From our simulations it follows that the Blake critical radius is not a good approximation for a fragmentation threshold. We demonstrated how the phase angle differences between a damped radially oscillating bubble and an incident sound field depend on shell parameters.

  6. Phase diagrams for sonoluminescing bubbles

    NASA Astrophysics Data System (ADS)

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

    1996-11-01

    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 space and also in the ambient radius versus gas concentration and versus forcing pressure state spaces. These phase diagrams are based on the thresholds for energy focusing in the bubble and two kinds of instabilities, namely (i) shape instabilities and (ii) diffusive instabilities. Stable SL only occurs in a tiny parameter window of large forcing pressure amplitude Pa˜1.2-1.5 atm and low gas concentration of less than 0.4% of the saturation. The upper concentration threshold becomes smaller with increased forcing. Our results quantitatively agree with experimental results of Putterman's UCLA group on argon, but not on air. However, air bubbles and other gas mixtures can also successfully be treated in this approach if in addition (iii) chemical instabilities are considered. All statements are based on the Rayleigh-Plesset ODE approximation of the bubble dynamics, extended in an adiabatic approximation to include mass diffusion effects. This approximation is the only way to explore considerable portions of parameter space, as solving the full PDEs is numerically too expensive. Therefore, we checked the adiabatic approximation by comparison with the full numerical solution of the advection diffusion PDE and find good agreement.

  7. Ethnic diversity deflates price bubbles

    PubMed Central

    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

  8. Transfusion practices in trauma

    PubMed Central

    Ramakrishnan, V Trichur; Cattamanchi, Srihari

    2014-01-01

    Resuscitation of a severely traumatised patient with the administration of crystalloids, or colloids along with blood products is a common transfusion practice in trauma patients. The determination of this review article is to update on current transfusion practices in trauma. A search of PubMed, Google Scholar, and bibliographies of published studies were conducted using a combination of key-words. Recent articles addressing the transfusion practises in trauma from 2000 to 2014 were identified and reviewed. Trauma induced consumption and dilution of clotting factors, acidosis and hypothermia in a severely injured patient commonly causes trauma-induced coagulopathy. Early infusion of blood products and early control of bleeding decreases trauma-induced coagulopathy. Hypothermia and dilutional coagulopathy are associated with infusion of large volumes of crystalloids. Hence, the predominant focus is on damage control resuscitation, which is a combination of permissive hypotension, haemorrhage control and haemostatic resuscitation. Massive transfusion protocols improve survival in severely injured patients. Early recognition that the patient will need massive blood transfusion will limit the use of crystalloids. Initially during resuscitation, fresh frozen plasma, packed red blood cells (PRBCs) and platelets should be transfused in the ratio of 1:1:1 in severely injured patients. Fresh whole blood can be an alternative in patients who need a transfusion of 1:1:1 thawed plasma, PRBCs and platelets. Close monitoring of bleeding and point of care coagulation tests are employed, to allow goal-directed plasma, PRBCs and platelets transfusions, in order to decrease the risk of transfusion-related acute lung injury. PMID:25535424

  9. Paediatric Blunt Torso Trauma

    PubMed Central

    Bhatti, Khalid M.; Taqi, Kadhim M.; Al-Harthy, Ahmed Z. S.; Hamid, Rana S.; Al-Balushi, Zainab N.; Sankhla, Dilip K.; Al-Qadhi, Hani A.

    2016-01-01

    Objectives: Trauma is the greatest cause of morbidity and mortality in paediatric/adolescent populations worldwide. This study aimed to describe trauma mechanisms, patterns and outcomes among children with blunt torso trauma admitted to the Sultan Qaboos University Hospital (SQUH) in Muscat, Oman. Methods: This retrospective single-centre study involved all children ≤12 years old with blunt torso trauma admitted for paediatric surgical care at SQUH between January 2009 and December 2013. Medical records were analysed to collect demographic and clinical data. Results: A total of 70 children were admitted with blunt torso trauma during the study period, including 39 (55.7%) male patients. The mean age was 5.19 ± 2.66 years. Of the cohort, 35 children (50.0%) received their injuries after having been hit by cars as pedestrians, while 19 (27.1%) were injured by falls, 12 (17.1%) during car accidents as passengers and four (5.7%) by falling heavy objects. According to computed tomography scans, thoracic injuries were most common (65.7%), followed by abdominal injuries (42.9%). The most commonly involved solid organs were the liver (15.7%) and spleen (11.4%). The majority of the patients were managed conservatively (92.9%) with a good outcome (74.3%). The mortality rate was 7.1%. Most deaths were due to multisystem involvement. Conclusion: Among children with blunt torso trauma admitted to SQUH, the main mechanism of injury was motor vehicle accidents. As a result, parental education and enforcement of infant car seat/child seat belt laws are recommended. Conservative management was the most successful approach. PMID:27226913

  10. OH Production Enhancement in Bubbling Pulsed Discharges

    SciTech Connect

    Lungu, Cristian P.; Porosnicu, Corneliu; Jepu, Ionut; Chiru, Petrica; Zaroschi, Valentin; Lungu, Ana M.; Saito, Nagahiro; Bratescu, Maria; Takai, Osamu; Velea, Theodor; Predica, Vasile

    2010-10-13

    The generation of active species, such as H{sub 2}O{sub 2}, O{sup *}, OH*, HO{sub 2}*, O{sub 3}, N{sub 2}{sup *}, etc, produced in aqueous solutions by HV pulsed discharges was studied in order to find the most efficient way in waste water treatment taking into account that these species are almost stronger oxidizers than ozone. Plasma was generated inside gas bubbles formed by the argon, air and oxygen gas flow between the special designed electrodes. The pulse width and pulse frequency influence was studied in order to increase the efficiency of the OH active species formation. The produced active species were investigated by optical emission spectroscopy and correlated with electrical parameters of the discharges (frequency, pulse width, amplitude, and rise and decay time).

  11. Trauma-Focused CBT for Youth Who Experience Ongoing Traumas

    ERIC Educational Resources Information Center

    Cohen, Judith A.; Mannarino, Anthony P.; Murray, Laura K.

    2011-01-01

    Many youth experience ongoing trauma exposure, such as domestic or community violence. Clinicians often ask whether evidence-based treatments containing exposure components to reduce learned fear responses to historical trauma are appropriate for these youth. Essentially the question is, if youth are desensitized to their trauma experiences, will…

  12. A novel trauma model: naturally occurring canine trauma.

    PubMed

    Hall, Kelly E; Sharp, Claire R; Adams, Cynthia R; Beilman, Gregory

    2014-01-01

    In human trauma patients, most deaths result from hemorrhage and brain injury, whereas late deaths, although rare, are the result of multiple organ failure and sepsis. A variety of experimental animal models have been developed to investigate the pathophysiology of traumatic injury and evaluate novel interventions. Similar to other experimental models, these trauma models cannot recapitulate conditions of naturally occurring trauma, and therefore therapeutic interventions based on these models are often ineffective. Pet dogs with naturally occurring traumatic injury represent a promising translational model for human trauma that could be used to assess novel therapies. The purpose of this article was to review the naturally occurring canine trauma literature to highlight the similarities between canine and human trauma. The American College of Veterinary Emergency and Critical Care Veterinary Committee on Trauma has initiated the establishment of a national network of veterinary trauma centers to enhance uniform delivery of care to canine trauma patients. In addition, the Spontaneous Trauma in Animals Team, a multidisciplinary, multicenter group of researchers has created a clinical research infrastructure for carrying out large-scale clinical trials in canine trauma patients. Moving forward, these national resources can be utilized to facilitate multicenter prospective studies of canine trauma to evaluate therapies and interventions that have shown promise in experimental animal models, thus closing the critical gap in the translation of knowledge from experimental models to humans and increasing the likelihood of success in phases 1 and 2 human clinical trials.

  13. Trauma-Focused CBT for Youth who Experience Ongoing Traumas

    PubMed Central

    Cohen, Judith A.; Mannarino, Anthony P.; Murray, Laura A.

    2011-01-01

    Many youth experience ongoing trauma exposure, such as domestic or community violence. Clinicians often ask whether evidence-based treatments containing exposure components to reduce learned fear responses to historical trauma are appropriate for these youth. Essentially the question is, if youth are desensitized to their trauma experiences, will this in some way impair their responding to current or ongoing trauma? The paper addresses practical strategies for implementing one evidence-based treatment, Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) for youth with ongoing traumas. Collaboration with local therapists and families participating in TF-CBT community and international programs elucidated effective strategies for applying TF-CBT with these youth. These strategies included: 1) enhancing safety early in treatment; 2) effectively engaging parents who experience personal ongoing trauma; and 3) during the trauma narrative and processing component focusing on a) increasing parental awareness and acceptance of the extent of the youths’ ongoing trauma experiences; b) addressing youths’ maladaptive cognitions about ongoing traumas; and c) helping youth differentiate between real danger and generalized trauma reminders. Case examples illustrate how to use these strategies in diverse clinical situations. Through these strategies TF-CBT clinicians can effectively improve outcomes for youth experiencing ongoing traumas. PMID:21855140

  14. Gravity driven flows of bubble suspensions.

    NASA Astrophysics Data System (ADS)

    Zenit, Roberto; Koch, Donald L.; Sangani, Ashok K.

    1999-11-01

    Experiments on vertical and inclined channels were performed to study the behavior of a mono-dispersed bubble suspension for which the dual limit of large Reynolds number and small Weber number is satisfied. A uniform stream of 1.5 mm diameter bubbles is produced by a bank of identical capillaries and coalescence is inhibited by addition of salt to the water. Measurements of the liquid velocity and bubble-probe collision rate are obtained with a hot wire anemometer. The gas volume fraction, bubble velocity, velocity variance and chord length are measured using a dual impedance probe. Image analysis is used to quantify the distributions of bubble size and aspect ratio. For vertical channels the bubble velocity is observed to decrease as the bubble concentration increases in accord with the predictions of Spelt and Sangani (1998). The bubble velocity variance arises largely due to bubble-wall and bubble-bubble collisions. For inclined channels, the strength of the shear flow is controlled by the extent of bubble segregation and the effective viscosity of the bubble phase. The measurements are compared with solutions of the averaged equations of motion for a range of gas volume fractions and channel inclination angles.

  15. Aspherical bubble dynamics and oscillation times

    SciTech Connect

    Godwin, R.P.; Chapyak, E.J.; Noack, J.; Vogel, A.

    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.

  16. Bursting Bubbles and Bilayers

    PubMed Central

    Wrenn, Steven P.; Dicker, Stephen M.; Small, Eleanor F.; Dan, Nily R.; Mleczko, Michał; Schmitz, Georg; Lewin, Peter A.

    2012-01-01

    This paper discusses various interactions between ultrasound, phospholipid monolayer-coated gas bubbles, phospholipid bilayer vesicles, and cells. The paper begins with a review of microbubble physics models, developed to describe microbubble dynamic behavior in the presence of ultrasound, and follows this with a discussion of how such models can be used to predict inertial cavitation profiles. Predicted sensitivities of inertial cavitation to changes in the values of membrane properties, including surface tension, surface dilatational viscosity, and area expansion modulus, indicate that area expansion modulus exerts the greatest relative influence on inertial cavitation. Accordingly, the theoretical dependence of area expansion modulus on chemical composition - in particular, poly (ethylene glyclol) (PEG) - is reviewed, and predictions of inertial cavitation for different PEG molecular weights and compositions are compared with experiment. Noteworthy is the predicted dependence, or lack thereof, of inertial cavitation on PEG molecular weight and mole fraction. Specifically, inertial cavitation is predicted to be independent of PEG molecular weight and mole fraction in the so-called mushroom regime. In the “brush” regime, however, inertial cavitation is predicted to increase with PEG mole fraction but to decrease (to the inverse 3/5 power) with PEG molecular weight. While excellent agreement between experiment and theory can be achieved, it is shown that the calculated inertial cavitation profiles depend strongly on the criterion used to predict inertial cavitation. This is followed by a discussion of nesting microbubbles inside the aqueous core of microcapsules and how this significantly increases the inertial cavitation threshold. Nesting thus offers a means for avoiding unwanted inertial cavitation and cell death during imaging and other applications such as sonoporation. A review of putative sonoporation mechanisms is then presented, including those

  17. Bubbles Responding to Ultrasound Pressure

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Bubble and Drop Nonlinear Dynamics (BDND) experiment was designed to improve understanding of how the shape and behavior of bubbles respond to ultrasound pressure. By understanding this behavior, it may be possible to counteract complications bubbles cause during materials processing on the ground. This 12-second sequence came from video downlinked from STS-94, July 5 1997, MET:3/19:15 (approximate). The BDND guest investigator was Gary Leal of the University of California, Santa Barbara. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced fluid dynamics experiments will be a part of investigations plarned for the International Space Station. (435KB, 13-second MPEG, screen 160 x 120 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300162.html.

  18. How safe is Bubble Soccer?

    PubMed

    Halani, Sameer H; Riley, Jonathan P; Pradilla, Gustavo; Ahmad, Faiz U

    2016-12-01

    Traumatic neurologic injury in contact sports is a rare but serious consequence for its players. These injuries are most commonly associated with high-impact collisions, for example in football, but are found in a wide variety of sports. In an attempt to minimize these injuries, sports are trying to increase safety by adding protection for participants. Most recently is the seemingly 'safe' sport of Bubble Soccer, which attempts to protect its players with inflatable plastic bubbles. We report a case of a 16-year-old male sustaining a cervical spine burst fracture with incomplete spinal cord injury while playing Bubble Soccer. To our knowledge, this is the first serious neurological injury reported in the sport.

  19. From rational bubbles to crashes

    NASA Astrophysics Data System (ADS)

    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 μ<1. We then outline the main results of Malevergne and Sornette, who extend the RE bubble 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 μ<1 for all assets. The distribution of price differences and of returns is dominated by the same power-law over an extended range of large returns. Although power-law tails are a pervasive feature of empirical data, the numerical value μ<1 is in disagreement with the usual empirical estimates μ≈3. We then discuss two extensions (the crash hazard rate model 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.

  20. Idioms of distress among trauma survivors: subtypes and clinical utility.

    PubMed

    Hinton, Devon E; Lewis-Fernández, Roberto

    2010-06-01

    In this introduction to the Special Issue on Trauma and Idioms of Distress, we provide an overview of the concept and typology of "idioms of distress," focusing particularly on their clinical utility. This includes the role of idioms as indicators of trauma exposure, of various types of psychopathology and of levels of distress, risk and functioning. It likewise includes the fact that idioms of distress may profoundly influence the personal meaning of having a trauma-related disorder, may shape the interpersonal course of the disorder and may pattern help-seeking and self-treatment. Finally, it illustrates the fact that idioms may also help clinicians understand sufferers' views of the causes of their distress, constitute key therapeutic targets and help increase therapeutic empathy and treatment adherence. This special issue focuses on the role played by idioms of distress in the local trauma ontology, the associations between the idioms and psychiatric disorders occurring in the context of trauma and the mechanisms by which the idioms profoundly influence the personal and interpersonal course of trauma-related disorders.

  1. Trauma and the endocrine system.

    PubMed

    Mesquita, Joana; Varela, Ana; Medina, José Luís

    2010-12-01

    The endocrine system may be the target of different types of trauma with varied consequences. The present article discusses trauma of the hypothalamic-pituitary axes, adrenal glands, gonads, and pancreas. In addition to changes in circulating hormone levels due to direct injury to these structures, there may be an endocrine response in the context of the stress caused by the trauma.

  2. Removal of hydrogen bubbles from nuclear reactors

    NASA Technical Reports Server (NTRS)

    Jenkins, R. V.

    1980-01-01

    Method proposed for removing large hydrogen bubbles from nuclear environment uses, in its simplest form, hollow spheres of palladium or platinum. Methods would result in hydrogen bubble being reduced in size without letting more radioactivity outside reactor.

  3. Electric field observations of equatorial bubbles

    NASA Astrophysics Data System (ADS)

    Aggson, T. L.; Maynard, N. C.; Hanson, W. B.; Saba, Jack L.

    1992-03-01

    Results from the double floating probe experiment performed on the San Marco D satellite are presented, with emphasis on the observation of large incremental changes in the convective electric field vector at the boundary of equatorial plasma bubbles. Attention is given to isolated bubble structures in the upper ionospheric F regions; these observed bubble encounters are divided into two types - type I (live bubbles) and type II (dead bubbles). Type I bubbles show varying degrees of plasma depletion and large upward velocities range up to 1000 km/s. The geometry of these bubbles is such that the spacecraft orbit may cut them where they are tilting either eastward or (more often) westward. Type II bubbles exhibit plasma density depletion but no appreciable upward convection. Both types of events are usually surrounded by a halo of plasma turbulence, which can extend considerably beyond the region of plasma depletion.

  4. Unorthodox bubbles when boiling in cold water

    NASA Astrophysics Data System (ADS)

    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.

  5. Soap Bubbles on a Cold Day.

    ERIC Educational Resources Information Center

    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)

  6. Electric field observations of equatorial bubbles

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Maynard, N. C.; Hanson, W. B.; Saba, Jack L.

    1992-01-01

    Results from the double floating probe experiment performed on the San Marco D satellite are presented, with emphasis on the observation of large incremental changes in the convective electric field vector at the boundary of equatorial plasma bubbles. Attention is given to isolated bubble structures in the upper ionospheric F regions; these observed bubble encounters are divided into two types - type I (live bubbles) and type II (dead bubbles). Type I bubbles show varying degrees of plasma depletion and large upward velocities range up to 1000 km/s. The geometry of these bubbles is such that the spacecraft orbit may cut them where they are tilting either eastward or (more often) westward. Type II bubbles exhibit plasma density depletion but no appreciable upward convection. Both types of events are usually surrounded by a halo of plasma turbulence, which can extend considerably beyond the region of plasma depletion.

  7. Unorthodox bubbles when boiling in cold water.

    PubMed

    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.

  8. Behavior of Rapidly Sheared Bubble Suspensions

    NASA Technical Reports Server (NTRS)

    Sangani, A. S.; Kushch, V. I.; Hoffmann, M.; Nahra, H.; Koch, D. L.; Tsang, Y.

    2002-01-01

    An experiment to be carried out aboard the International Space Station is described. A suspension consisting of millimeter-sized bubbles in water containing some dissolved salt, which prevents bubbles from coalescing, will be sheared in a Couette cylindrical cell. Rotation of the outer cylinder will produce centrifugal force which will tend to accumulate the bubbles near the inner wall. The shearing will enhance collisions among bubbles creating thereby bubble phase pressure that will resist the tendency of the bubbles to accumulate near the inner wall. The bubble volume fraction and velocity profiles will be measured and compared with the theoretical predictions. Ground-based research on measurement of bubble phase properties and flow in vertical channel are described.

  9. Bubble memory module for spacecraft application

    NASA Technical Reports Server (NTRS)

    Hayes, P. J.; Looney, K. T.; Nichols, C. D.

    1985-01-01

    Bubble domain technology offers an all-solid-state alternative for data storage in onboard data systems. A versatile modular bubble memory concept was developed. The key module is the bubble memory module which contains all of the storage devices and circuitry for accessing these devices. This report documents the bubble memory module design and preliminary hardware designs aimed at memory module functional demonstration with available commercial bubble devices. The system architecture provides simultaneous operation of bubble devices to attain high data rates. Banks of bubble devices are accessed by a given bubble controller to minimize controller parts. A power strobing technique is discussed which could minimize the average system power dissipation. A fast initialization method using EEPROM (electrically erasable, programmable read-only memory) devices promotes fast access. Noise and crosstalk problems and implementations to minimize these are discussed. Flight memory systems which incorporate the concepts and techniques of this work could now be developed for applications.

  10. Early Childhood Trauma

    ERIC Educational Resources Information Center

    National Child Traumatic Stress Network, 2010

    2010-01-01

    Early childhood trauma generally refers to the traumatic experiences that occur to children aged 0-6. Because infants' and young children's reactions may be different from older children's, and because they may not be able to verbalize their reactions to threatening or dangerous events, many people assume that young age protects children from the…

  11. Ultrasound in cardiac trauma.

    PubMed

    Saranteas, Theodosios; Mavrogenis, Andreas F; Mandila, Christina; Poularas, John; Panou, Fotios

    2017-04-01

    In the perioperative period, the emergency department or the intensive care unit accurate assessment of variable chest pain requires meticulous knowledge, diagnostic skills, and suitable usage of various diagnostic modalities. In addition, in polytrauma patients, cardiac injury including aortic dissection, pulmonary embolism, acute myocardial infarction, and pericardial effusion should be immediately revealed and treated. In these patients, arrhythmias, mainly tachycardia, cardiac murmurs, or hypotension must alert physicians to suspect cardiovascular trauma, which would potentially be life threatening. Ultrasound of the heart using transthoracic and transesophageal echocardiography are valuable diagnostic tools that can be used interchangeably in conjunction with other modalities such as the electrocardiogram and computed tomography for the diagnosis of cardiovascular abnormalities in trauma patients. Although ultrasound of the heart is often underused in the setting of trauma, it does have the advantages of being easily accessible, noninvasive, and rapid bedside assessment tool. This review article aims to analyze the potential cardiac injuries in trauma patients, and to provide an elaborate description of the role of echocardiography for their accurate diagnosis.

  12. Structured Sensory Trauma Interventions

    ERIC Educational Resources Information Center

    Steele, William; Kuban, Caelan

    2010-01-01

    This article features the National Institute of Trauma and Loss in Children (TLC), a program that has demonstrated via field testing, exploratory research, time series studies, and evidence-based research studies that its Structured Sensory Intervention for Traumatized Children, Adolescents, and Parents (SITCAP[R]) produces statistically…

  13. Fundamental study on transient bubble (slug) behavior by characterizing transient forces of solid particles in fluidized beds. Topical report, January 1991--June 1992

    SciTech Connect

    Kono, H.

    1992-10-01

    The objective of this work is to recognize and interpret the signals of transient motion of bubbles (slugs) in fluidized beds (METC/DOE) by measuring and utilizing the signals of transient gas phase pressure fluctuation, and also by taking the video pictures of transient motions of the bubbles and emulsion phase in fluidized beds. The two signals were measured simultaneously in a three dimensional fluidized bed. Correlation study on the voidage signal and pressure fluctuation was carried out. A domain concept was introduced and new bubble classification was suggested. A video recording approach was also developed to record the transient bubble motion in a two dimensional fluidized bed with a special consideration. This new approach enhances the understanding of bubble image and the physical meaning of transient particle forces. The fundamental mechanism of bubble flow was experimentally investigated and interesting new findings of the transient bubble flow were obtained.

  14. Magma mixing enhanced by bubble segregation

    NASA Astrophysics Data System (ADS)

    Wiesmaier, S.; Daniele, M.; Renggli, C.; Perugini, D.; De Campos, C.; Hess, K. U.; Ertel-Ingrisch, W.; Lavallée, Y.; Dingwell, D. B.

    2014-12-01

    Rising bubbles may significantly affect magma mixing paths as has been demonstrated by analogue experiments in the past. Here, bubble-advection experiments are performed for the first time employing natural materials at magmatic temperatures. Cylinders of basaltic glass were placed below cylinders of rhyolite glass. Upon melting, interstitial air formed bubbles that rose into the rhyolite melt, thereby entraining tails of basaltic liquid. The formation of plume-like filaments of advected basalt within the rhyolite was characterized by microCT and subsequent high-resolution EMP analyses. Melt entrainment by bubble ascent appears as efficient mechanism to mingle contrasting melt compositions. MicroCT imaging shows bubbles trailing each other and trails of multiple bubbles having converged. Rheological modelling of the filaments yields viscosities of up to 2 orders of magnitude lower than for the surrounding rhyolitic liquid. Such a viscosity contrast implies that subsequent bubbles rising are likely to follow the same pathways that previously ascending bubbles have generated. Filaments formed by multiple bubbles would thus experience episodic replenishment with mafic material. Fundamental implications for the concept of bubble advection in magma mixing are thus a) an acceleration of mixing because of decreased viscous resistance for bubbles inside filaments and b) non-conventional diffusion systematics because of intermittent supply of mafic material (instead of a single pulse) inside a filament. Inside these filaments, the mafic material was variably hybridised to andesitic through rhyolitic composition. Compositional profiles alone are ambiguous, however, to determine whether single or multiple bubbles were involved during formation of a filament. Statistical analysis, employing concentration variance as measure of homogenisation, demonstrates that also filaments appearing as single-bubble filaments are likely to have experienced multiple bubbles passing through

  15. Local Bubble Session Summary: Putting it all Together

    NASA Astrophysics Data System (ADS)

    Shelton, Robin L.

    2010-05-01

    This talk summarizes the meeting-in-a-meeting on the local interstellar environment. By discussing the heliosphere, nearby clouds, the Local Bubble, and the Local Cavity, this session aims to provide a comprehensive understanding of our neighborhood. The nearest regions, the heliosphere and its interaction zone with the interstellar medium, have been studied using data from IBEX and Voyager. Among the new results are estimates of the interstellar magnetic field strength. The Local Bubble has been studied through observations of X-ray photons, however, newer work suggests that many of these photons originate in the heliosphere and result from solar wind charge exchange. A call for revisions to the Local Bubble model will be noted in this talk. According to radio, optical, and ultraviolet observations, many neutral clouds reside within the Local Bubble/Local Cavity region. Studies of these clouds, including discoveries of new ones and evidence of turbulence, will be presented in the special session and summarized in this talk. The Local Cavity, whose spatial extent has been mapped with ever increasing resolution, will also be reviewed. Because the interstellar medium is not static and the Sun is not fixed to a firmament of interstellar gas, time variability will be discussed. Lastly, the physical processes that govern the local environment will be presented.

  16. Frictional drag reduction by bubble injection

    NASA Astrophysics Data System (ADS)

    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.

  17. LRL 25-inch Bubble Chamber

    DOE R&D Accomplishments Database

    Alvarez, L. W.; Gow, J. D.; Barrera, F.; Eckman, G.; Shand, J.; Watt, R.; Norgren, D.; Hernandez, H. P.

    1964-07-08

    The recently completed 25-inch hydrogen bubble chamber combines excellent picture quality with a fast operating cycle. The chamber has a unique optical system and is designed to take several pictures each Bevatron pulse, in conjunction with the Bevatron rapid beam ejection system.

  18. Ice bubbles confirm big chill

    SciTech Connect

    Kerr, R.A.

    1996-06-14

    Clues buried in Greenland`s icesheet indicate that during the last ice age, the climate repeatedly warmed sharply, only to slide into a renewed chill lasting thousands of years. New indicators derived from trapped bubbles of ancient gases, nitrogen and methane, indicate that these were indeed catastrophic events. This article describes the research and adjunct issues.

  19. Bubble-driven inertial micropump

    NASA Astrophysics Data System (ADS)

    Torniainen, Erik D.; Govyadinov, Alexander N.; Markel, David P.; Kornilovitch, Pavel E.

    2012-12-01

    The fundamental action of the bubble-driven inertial micropump is investigated. The pump has no moving parts and consists of a thermal resistor placed asymmetrically within a straight channel connecting two reservoirs. Using numerical simulations, the net flow is studied as a function of channel geometry, resistor location, vapor bubble strength, fluid viscosity, and surface tension. Two major regimes of behavior are identified: axial and non-axial. In the axial regime, the drive bubble either remains inside the channel, or continues to grow axially when it reaches the reservoir. In the non-axial regime, the bubble grows out of the channel and in all three dimensions while inside the reservoir. The net flow in the axial regime is parabolic with respect to the hydraulic diameter of the channel cross-section, but in the non-axial regime it is not. From numerical modeling, it is determined that the net flow is maximal when the axial regime crosses over to the non-axial regime. To elucidate the basic physical principles of the pump, a phenomenological one-dimensional model is developed and solved. A linear array of micropumps has been built using silicon-SU8 fabrication technology that is used to manufacture thermal inkjet printheads. Semi-continuous pumping across a 2 mm-wide channel has been demonstrated experimentally. Measured net flow with respect to viscosity variation is in excellent agreement with simulation results.

  20. Bursting the Taylor cone bubble

    NASA Astrophysics Data System (ADS)

    Pan, Zhao; Truscott, Tadd

    2014-11-01

    A soap bubble fixed on a surface and placed in an electric field will take on the shape of a cone rather than constant curvature (dome) when the electrical field is not present. The phenomenon was introduced by J. Zeleny (1917) and studied extensively by C.T. Wilson & G.I. Taylor (1925). We revisit the Taylor cone problem by studying the deformation and bursting of soap bubbles in a point charge electric field. A single bubble takes on the shape of a cone in the electric field and a high-speed camera equipped with a micro-lens is used to observe the unsteady dynamics at the tip. Rupture occurs as a very small piece of the tip is torn away from the bubble toward the point charge. Based on experiments, a theoretical model is developed that predicts when rupture should occur. This study may help in the design of foam-removal techniques in engineering and provide a better understanding of an electrified air-liquid interface.

  1. Models of cylindrical bubble pulsation

    PubMed Central

    Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hay, Todd A.; Hamilton, Mark F.

    2012-01-01

    Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion. PMID:22978863

  2. Impurity bubbles in a BEC

    NASA Astrophysics Data System (ADS)

    Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

    2013-05-01

    Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

  3. Affirmative Discrimination and the Bubble

    ERIC Educational Resources Information Center

    Clegg, Roger

    2011-01-01

    In this essay, the author discusses how affirmative action contributed to an unnatural rise in enrollments in college. In considering the higher education bubble, he makes the case that as the opposition to preferences continues to build, the momentum of this trend will only increase as funding shrinks. He offers some tentative answers to a series…

  4. "Financial Bubbles" and Monetary Policy

    ERIC Educational Resources Information Center

    Tikhonov, Yuriy A.; Pudovkina, Olga E.; Permjakova, Juliana V.

    2016-01-01

    The relevance of this research is caused by the need of strengthening a role of monetary regulators to prevent financial bubbles in the financial markets. The aim of the article is the analysis of a problem of crisis phenomena in the markets of financial assets owing to an inadequate growth of their cost, owing to subjective reasons. The leading…

  5. Neutron Detection via Bubble Chambers

    SciTech Connect

    Jordan, David V.; Ely, James H.; Peurrung, Anthony J.; Bond, Leonard J.; Collar, J. I.; Flake, Matthew; Knopf, Michael A.; Pitts, W. K.; Shaver, Mark W.; Sonnenschein, Andrew; Smart, John E.; Todd, Lindsay C.

    2005-10-06

    The results of a Pacific Northwest National Laboratory (PNNL) exploratory research project investigating the feasibility of fast neutron detection using a suitably prepared and operated, pressure-cycled bubble chamber are described. The research was conducted along two parallel paths. Experiments with a slow pressure-release Halon chamber at the Enrico Fermi Institute at the University of Chicago showed clear bubble nucleation sensitivity to an AmBe neutron source and insensitivity to the 662 keV gammas from a 137Cs source. Bubble formation was documented via high-speed (1000 frames/sec) photography, and the acoustic signature of bubble formation was detected using a piezo-electric transducer element mounted on the base of the chamber. The chamber’s neutron sensitivity as a function of working fluid temperature was mapped out. The second research path consisted of the design, fabrication, and testing of a fast pressure-release Freon-134a chamber at PNNL. The project concluded with successful demonstrations of the PNNL chamber’s AmBe neutron source sensitivity and 137Cs gamma insensitivity. The source response tests of the PNNL chamber were documented with high-speed photography.

  6. The effects of bubble-bubble interactions on pressures and temperatures produced by bubbles collapsing near a rigid surface

    NASA Astrophysics Data System (ADS)

    Alahyari Beig, Shahaboddin; Johnsen, Eric

    2016-11-01

    Cavitation occurs in a wide range of hydraulic applications, and one of its most important consequences is structural damage to neighboring surfaces following repeated bubble collapse. A number of studies have been conducted to predict the pressures produced by the collapse of a single bubble. However, the collapse of multiple bubbles is known to lead to enhanced collapse pressures. In this study, we quantify the effects of bubble-bubble interactions on the bubble dynamics and pressures/temperatures produced by the collapse of a pair of bubbles near a rigid surface. For this purpose, we use an in-house, high-order accurate shock- and interface-capturing method to solve the 3D compressible Navier-Stokes equations for gas/liquid flows. The non-spherical bubble dynamics are investigated and the subsequent pressure and temperature fields are characterized based on the relevant parameters entering the problem: stand-off distance, geometrical configuation, collapse strength. We demonstrate that bubble-bubble interactions amplify/reduce pressures and temperatures produced at the collapse, and increase the non-sphericity of the bubbles and the collapse time, depending on the flow parameters.

  7. Tiny Bubbles in my BEC

    SciTech Connect

    Blinova, Alina A.

    2012-08-01

    Ultracold atomic gases provide a unique way for exploring many-body quantum phenomena that are inaccessible to conventional low-temperature experiments. Nearly two decades ago the Bose-Einstein condensate (BEC) - an ultracold gas of bosons in which almost all bosons occupy the same single-particle state - became experimentally feasible. Because a BEC exhibits superfluid properties, it can provide insights into the behavior of low-temperature helium liquids. We describe the case of a single distinguishable atom (an impurity) embedded in a BEC and strongly coupled to the BEC bosons. Depending on the strength of impurity-boson and boson-boson interactions, the impurity self-localizes into two fundamentally distinct regimes. The impurity atom can behave as a tightly localized 'polaron,' akin to an electron in a dielectric crystal, or as a 'bubble,' an analog to an electron bubble in superfluid helium. We obtain the ground state wavefunctions of the impurity and BEC by numerically solving the two coupled Gross-Pitaevskii equations that characterize the system. We employ the methods of imaginary time propagation and conjugate gradient descent. By appropriately varying the impurity-boson and boson-boson interaction strengths, we focus on the polaron to bubble crossover. Our results confirm analytical predictions for the polaron limit and uncover properties of the bubble regime. With these results we characterize the polaron to bubble crossover. We also summarize our findings in a phase diagram of the BEC-impurity system, which can be used as a guide in future experiments.

  8. Antioscillons from bubble collisions at finite temperature

    NASA Astrophysics Data System (ADS)

    Mersini-Houghton, Laura

    2014-04-01

    We study the role of the topology of bubbles at finite temperatures plays on collisions and the existence of new field configurations. We show that in the case of false vacuum decay at finite temperature, the cylindrical symmetry of bubbles admits a new exotic field with negative energies, the antiperiodic "twisted" field. New field configurations arise generically, not only at finite temperatures but whenever a cluster of bubbles resulting from collisions form nontrivial topologies. The interaction of both configurations induces instabilites on the bubble. Collisions of bubbles occupied by the new fields can lead to the emergence of new structures, named antioscillons.

  9. Asymmetric interface temperature during vapor bubble growth

    NASA Astrophysics Data System (ADS)

    Diana, A.; Castillo, M.; Steinberg, T.; Brutin, D.

    2013-07-01

    We investigate the nucleation, growth, and detachment of single vapor bubbles at the interface microscale. Shear flow is used to investigate pool and convective boiling situations using visible and infrared visualizations. We determine a threshold Reynolds number for the onset of asymmetric interfacial temperatures. Below this threshold, bubble growth is geometrically and thermally symmetric, while above, bubbles no longer grow thermally symmetrically. This is explained by the dominance of convective heat transfer removal over viscous effects at the bubble interface. We experimentally demonstrate asymmetric interfacial temperature profiles that should be taken into account for future bubble growth modeling.

  10. Alternative model of single-bubble sonoluminescence

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    1997-12-01

    A model of single-bubble sonoluminescence (SBSL) is constructed. In the model, the temperature is assumed to be spatially uniform inside the bubble except at the thermal boundary layer near the bubble wall even at the strong collapse based on the theoretical results of Kwak and Na [Phys. Rev. Lett. 77, 4454 (1996)]. In the model, the effect of the kinetic energy of gases inside the bubble is taken into account, which heats up the whole bubble when gases stop their motions at the end of the strong collapse. In the model, a bubble in water containing air is assumed to consist mainly of argon based on the hypothesis of Lohse et al. [Phys. Rev. Lett. 78, 1359 (1997)]. Numerical calculations under a SBSL condition reveal that the kinetic energy of gases heats up the whole bubble considerably. It is also clarified that vapor molecules (H2O) undergo chemical reactions in the heated interior of the bubble at the collapse and that chemical reactions decrease the temperature inside the bubble considerably. It is suggested that SBSL originates in thermal radiation from the whole bubble rather than a local point (the bubble center) heated by a converging spherical shock wave widely suggested in the previous theories of SBSL.

  11. Mechanics of gas-vapor bubbles

    NASA Astrophysics Data System (ADS)

    Hao, Yue; Zhang, Yuhang; Prosperetti, Andrea

    2017-03-01

    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 condensation and of gas diffusion in the liquid and in the bubble. This paper presents a model for this situation and illustrates by means of examples several physical processes that can occur: a bubble undergoing a temporary pressure reduction, which makes the liquid temporarily superheated; a bubble subjected to a burst of sound; and a bubble continuously growing by rectified diffusion of heat in the presence of an incondensible gas.

  12. Operation Brain Trauma Therapy

    DTIC Science & Technology

    2011-10-01

    OBTT consortium as the drug #2 for primary screening . Based on that same review , two doses were selected, namely 5000 or 10,000 IU/kg, by a single IV...in drug screening . This review article discusses a consortium called opera- tion brain trauma therapy (OBTT) that was recently established in attempt...consortium that identifies the most promising therapies and compares them across a spectrum of the state -of-the- art models and injury levels. The most

  13. Substance Abuse and Trauma.

    PubMed

    Simmons, Shannon; Suárez, Liza

    2016-10-01

    There is a strong, bidirectional link between substance abuse and traumatic experiences. Teens with cooccurring substance use disorders (SUDs) and posttraumatic stress disorder (PTSD) have significant functional and psychosocial impairment. Common neurobiological foundations point to the reinforcing cycle of trauma symptoms, substance withdrawal, and substance use. Treatment of teens with these issues should include a systemic and integrated approach to both the SUD and the PTSD.

  14. Trauma in pregnancy.

    PubMed

    Bremer, C; Cassata, L

    1986-12-01

    The pregnant woman is exposed to the same risks as the non-pregnant woman for sustaining a traumatic injury, but because of the multiple physiologic changes that occur during pregnancy, the assessment and treatment of such patients must be adapted accordingly. This article discusses these normal physiologic changes, their effect on response to trauma, and the comprehensive care of the patient using the nursing process.

  15. Endovascular Therapy in Trauma

    DTIC Science & Technology

    2014-11-23

    patients. The use of endovascu- lar techniques in trauma can be considered in three broad categories: (1) large- vessel repair (e.g. covered stent repair...2) mid- to small- vessel hemostasis (e.g. coils, plugs, and hemostatic agents), and (3) large- vessel balloon occlusion for resuscitation (e.g...a diagnostic contrast study (i.e. angiography), accomplish large- vessel occlusion, or render a therapy for vessel disruption and/or bleeding. Not

  16. INTERACTIONS OF THE INFRARED BUBBLE N4 WITH ITS SURROUNDINGS

    SciTech Connect

    Liu, Hong-Li; Li, Jin-Zeng; Yuan, Jing-Hua; Huang, Maohai; Huang, Ya-Fang; Zhang, Si-Ju; Wu, Yuefang; Liu, Tie; Dubner, G.; Paron, S.; Ortega, M. E.; Molinari, Sergio; Zavagno, Annie; Samal, Manash R.

    2016-02-10

    The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with H ii regions have been considered to be good samples for investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the H ii region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 × 10{sup 22} cm{sup −2}, mean volume density of about 4.4 × 10{sup 4} cm{sup −3}, and a mean mass of 320 M{sub ⊙}. In addition, from PAH emission seen at 8 μm, free–free emission detected at 20 cm, and a probability density function in special regions, we could identify clear signatures of the influence of the H ii region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source.

  17. Military Trauma System in Afghanistan: Lessons for Civil Systems?

    DTIC Science & Technology

    2013-12-01

    of special interest && of outstanding interest 1. Bailey J, Spott MA, Costanzo G, et al. Joint trauma system: development, conceptual framework and...optimal elements [e manual]. US Department of Defense. US Army Institute for Surgical Research; 2012. 2. Eastridge BJ, Costanzo G, Jenkins D, et al

  18. Psychological Trauma in the Schools: A Retrospective Study.

    ERIC Educational Resources Information Center

    Zelikoff, Wendy L.; Hyman, Irwin A.

    An increase in clinical cases indicates that trauma in school children can be connected to teacher abuse. A survey was administered to 35 college undergraduates, 40 school teachers, 41 special educators, and 65 mixed individuals from Pennsylvania, New Jersey, New York, Delaware, Georgia, and Puerto Rico to determine the nature of the abuse, its…

  19. Reflections on 20 Years of Research on Violence and Trauma

    ERIC Educational Resources Information Center

    Forde, David R.

    2005-01-01

    This article is part of a special issue reflecting on what people have learned about violence and trauma over the past 20 years and where we need to go in the next 10 years. The author emphasizes the importance of learning to communicate in order to form effective community partnerships. Evidence-based research is noted as a methodological…

  20. Imaging of laryngeal trauma.

    PubMed

    Becker, Minerva; Leuchter, Igor; Platon, Alexandra; Becker, Christoph D; Dulguerov, Pavel; Varoquaux, Arthur

    2014-01-01

    External laryngeal trauma is a rare but potentially life-threatening situation in the acutely injured patient. Trauma mechanism and magnitude, maximum focus of the applied force, and patient related factors, such as age and ossification of the laryngeal cartilages influence the spectrum of observed injuries. Their correct diagnosis and prompt management are paramount in order to avoid patient death or long-term impairment of breathing, swallowing and speaking. The current review provides a comprehensive approach to the radiologic interpretation of imaging studies performed in patients with suspected laryngeal injury. It describes the key anatomic structures that are relevant in laryngeal trauma and discusses the clinical role of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the acute emergency situation. The added value of two-dimensional multiplanar reconstructions (2D MPR), three-dimensional volume rendering (3D VR) and virtual endoscopy (VE) for the non-invasive evaluation of laryngeal injuries and for treatment planning is discussed. The clinical presentation, biomechanics of injury, diagnostic pitfalls and pearls, common and uncommon findings are reviewed with emphasis of fracture patterns, involvement of laryngeal joints, intra- and extralaryngeal soft tissue injuries, and complications seen in the acute emergency situation. The radiologic appearance of common and less common long-term sequelae, as well as treatment options are equally addressed.

  1. The trauma team--a system of initial trauma care.

    PubMed Central

    Adedeji, O. A.; Driscoll, P. A.

    1996-01-01

    Trauma remains the leading cause of death under the age of 35 years. England and Wales lost 252,000 working years from accidental deaths, including poison, in 1992. In this country, preventable deaths from trauma are inappropriately high. In many hospitals there are not enough personnel; in the majority, there are no recognisable trauma care systems, which can reduce preventable deaths to a minimum. The appropriateness of trauma centres for this country is being assessed in Stoke-on-Trent, and a report is due out later this year. Even if the recommendation is made to establish such centres, it is unlikely that many will be set up. Consequently most hospitals will have to rely on their own resources to set up and run a trauma team. This type of trauma care system is the subject of this article. PMID:8977939

  2. Generation of Bubbly Suspensions in Low Gravity

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Hoffmann, Monica I.; Hussey, Sam; Bell, Kimberly R.

    2000-01-01

    Generation of a uniform monodisperse bubbly suspension in low gravity is a rather difficult task because bubbles do not detach as easily as on Earth. Under microgravity, the buoyancy force is not present to detach the bubbles as they are formed from the nozzles. One way to detach the bubbles is to establish a detaching force that helps their detachment from the orifice. The drag force, established by flowing a liquid in a cross or co-flow configuration with respect to the nozzle direction, provides this additional force and helps detach the bubbles as they are being formed. This paper is concerned with studying the generation of a bubbly suspension in low gravity in support of a flight definition experiment titled "Behavior of Rapidly Sheared Bubbly Suspension." Generation of a bubbly suspension, composed of 2 and 3 mm diameter bubbles with a standard deviation <10% of the bubble diameter, was identified as one of the most important engineering/science issues associated with the flight definition experiment. This paper summarizes the low gravity experiments that were conducted to explore various ways of making the suspension. Two approaches were investigated. The first was to generate the suspension via a chemical reaction between the continuous and dispersed phases using effervescent material, whereas the second considered the direct injection of air into the continuous phase. The results showed that the reaction method did not produce the desired bubble size distribution compared to the direct injection of bubbles. However, direct injection of air into the continuous phase (aqueous salt solution) resulted in uniform bubble-diameter distribution with acceptable bubble-diameter standard deviation.

  3. Suppression of cavitation inception by gas bubble injection: a numerical study focusing on bubble-bubble interaction.

    PubMed

    Ida, Masato; Naoe, Takashi; Futakawa, Masatoshi

    2007-10-01

    The dynamic behavior of cavitation and gas bubbles under negative pressure has been studied numerically to evaluate the effect of gas bubble injection into a liquid on the suppression of cavitation inception. In our previous studies, it was demonstrated by direct observation that cavitation occurs in liquid mercury when mechanical impacts are imposed, and this will cause cavitation damage in spallation neutron sources, in which liquid mercury is bombarded by a high-power proton beam. In the present paper, we describe numerical investigations of the dynamics of cavitation bubbles in liquid mercury using a multibubble model that takes into account the interaction of a cavitation bubble with preexisting gas bubbles through bubble-radiated pressure waves. The numerical results suggest that, if the mercury includes gas bubbles whose equilibrium radius is much larger than that of the cavitation bubble, the explosive expansion of the cavitation bubble (i.e., cavitation inception) is suppressed by the positive-pressure wave radiated by the injected bubbles, which decreases the magnitude of the negative pressure in the mercury.

  4. A Civilian/Military Trauma Institute: National Trauma Coordinating Center

    DTIC Science & Technology

    2015-12-01

    funding . The infrastructure/process is streamlined and efficient leading to the selection of research projects based on a solid scientific, peer review...National Trauma Institute (NTI) to build on the establishment of NTI as a national coordinating center for trauma research funding . In addition, a... research funding . 1. Requests for proposals (RFP) based on areas of scientific merit in trauma and emergency or critical care will be prepared and

  5. Sonoporation from Jetting Cavitation Bubbles

    PubMed Central

    Ohl, Claus-Dieter; Arora, Manish; Ikink, Roy; de Jong, Nico; 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 detachment of cells. Cells at the edge of the circular area of detachment are found to be permanently porated, whereas cells at some distance from the detachment area undergo viable cell membrane poration (sonoporation). The wall flow field leading to cell detachment is modeled with a self-similar solution for a wall jet, together with a kinetic ansatz of adhesive bond rupture. The self-similar solution for the δ-type wall jet compares very well with the full solution of the Navier-Stokes equation for a jet of finite thickness. Apart from annular sites of sonoporation we also find more homogenous patterns of molecule delivery with no cell detachment. PMID:16950843

  6. Etiology of gas bubble disease

    SciTech Connect

    Bouck, G.R.

    1980-11-01

    Gas bubble disease is a noninfectious, physically induced process caused by uncompensated hyperbaric pressure of total dissolved gases. When pressure compensation is inadequate, dissolved gases may form emboli (in blood) and emphysema (in tissues). The resulting abnormal physical presence of gases can block blood vessels (hemostasis) or tear tissues, and may result in death. Population mortality is generally skewed, in that the median time to death occurs well before the average time to death. Judged from mortality curves, three stages occur in gas bubble disease: (1) a period of gas pressure equilibrium, nonlethal cavitation, and increasing morbidity; (2) a period of rapid and heavy mortality; and (3) a period of protracted survival, despite lesions, and dysfunction that eventually terminates in total mortality. Safe limits for gas supersaturation depend on species tolerance and on factors that differ among hatcheries and rivers, between continuous and intermittent exposures, and across ranges of temperature and salinity.

  7. Evaluation of care of dentoalveolar trauma

    PubMed Central

    FARINIUK, Luiz Fernando; de SOUSA, Maria Helena; WESTPHALEN, Vânia Portela Dietzel; CARNEIRO, Everdan; SILVA NETO, Ulisses X; ROSKAMP, Liliane; CAVALI, Ana Égide

    2010-01-01

    Objectives The aim of this study was to evaluate cases of dental trauma treated at the specialized center of Pontifical Catholic University of Paraná, Curitiba, Brazil, during a period of 2 years. Material and Methods A total of 647 patients were evaluated and treated between 2003 and 2005. Data obtained from each patient were tabulated and analyzed as to gender, age, etiology, time elapsed after the injury, diagnosis (type of trauma), and affected teeth. Results The results revealed that male individuals aged 7 to 13 years presented the highest prevalence of injury, and falling was the main causal factor. In most cases, the time elapsed between the accident and the first care ranged from 4 to 24 h. A total of 1,747 teeth were affected, with higher incidence of concussion/subluxation and coronal fracture, followed by lateral luxation and avulsion. The permanent maxillary central incisors were the most commonly affected teeth. Conclusion The frequency and causes of dentoalveolar trauma should be investigated for identification of risk groups, treatment demands and costs in order to allow for the establishment of effective preventive measures that can reduce the treatment duration and costs for both patients and oral health services. PMID:20835567

  8. Bubble-induced cave collapse.

    PubMed

    Girihagama, Lakshika; Nof, Doron; Hancock, Cathrine

    2015-01-01

    Conventional wisdom among cave divers is that submerged caves in aquifers, such as in Florida or the Yucatan, are unstable due to their ever-growing size from limestone dissolution in water. Cave divers occasionally noted partial cave collapses occurring while they were in the cave, attributing this to their unintentional (and frowned upon) physical contact with the cave walls or the aforementioned "natural" instability of the cave. Here, we suggest that these cave collapses do not necessarily result from cave instability or contacts with walls, but rather from divers bubbles rising to the ceiling and reducing the buoyancy acting on isolated ceiling rocks. Using familiar theories for the strength of flat and arched (un-cracked) beams, we first show that the flat ceiling of a submerged limestone cave can have a horizontal expanse of 63 meters. This is much broader than that of most submerged Florida caves (~ 10 m). Similarly, we show that an arched cave roof can have a still larger expanse of 240 meters, again implying that Florida caves are structurally stable. Using familiar bubble dynamics, fluid dynamics of bubble-induced flows, and accustomed diving practices, we show that a group of 1-3 divers submerged below a loosely connected ceiling rock will quickly trigger it to fall causing a "collapse". We then present a set of qualitative laboratory experiments illustrating such a collapse in a circular laboratory cave (i.e., a cave with a circular cross section), with concave and convex ceilings. In these experiments, a metal ball represented the rock (attached to the cave ceiling with a magnet), and the bubbles were produced using a syringe located at the cave floor.

  9. Bubble-Induced Cave Collapse

    PubMed Central

    Girihagama, Lakshika; Nof, Doron; Hancock, Cathrine

    2015-01-01

    Conventional wisdom among cave divers is that submerged caves in aquifers, such as in Florida or the Yucatan, are unstable due to their ever-growing size from limestone dissolution in water. Cave divers occasionally noted partial cave collapses occurring while they were in the cave, attributing this to their unintentional (and frowned upon) physical contact with the cave walls or the aforementioned “natural” instability of the cave. Here, we suggest that these cave collapses do not necessarily result from cave instability or contacts with walls, but rather from divers bubbles rising to the ceiling and reducing the buoyancy acting on isolated ceiling rocks. Using familiar theories for the strength of flat and arched (un-cracked) beams, we first show that the flat ceiling of a submerged limestone cave can have a horizontal expanse of 63 meters. This is much broader than that of most submerged Florida caves (~ 10 m). Similarly, we show that an arched cave roof can have a still larger expanse of 240 meters, again implying that Florida caves are structurally stable. Using familiar bubble dynamics, fluid dynamics of bubble-induced flows, and accustomed diving practices, we show that a group of 1-3 divers submerged below a loosely connected ceiling rock will quickly trigger it to fall causing a “collapse”. We then present a set of qualitative laboratory experiments illustrating such a collapse in a circular laboratory cave (i.e., a cave with a circular cross section), with concave and convex ceilings. In these experiments, a metal ball represented the rock (attached to the cave ceiling with a magnet), and the bubbles were produced using a syringe located at the cave floor. PMID:25849088

  10. Development and interactions of two inert gas bubbles during decompression.

    PubMed

    Jiang, Y; Homer, L D; Thalmann, E D

    1996-09-01

    A mathematical model has been developed to simulate the evolution of two inert gas bubbles in tissue. This is useful for understanding the dynamics of bubbles that presumably arise during decompression. It is assumed that they are spherical and that the tissue volume surrounding them is infinite. The total pressure in each bubble is determined by the barometric and metabolic gas pressures as well as the pressure due to surface tension. Bipolar coordinates are employed to determine the inert gas pressure distribution. Two coupled governing equations for bubble radii are then derived and solved numerically. The results demonstrate how bubble evolution is affected by the distance between bubbles and the initial bubble radii. The existence time and bubble surface flux of two equal-sized bubbles are calculated and compared with those of a single gas bubble model. The results indicate that when two bubbles are very close, it takes 20% more time for two bubbles to dissolve than for a single one, and the total surface flux of two bubbles is nearly 20% less than twice of a single bubble. When the center-to-center distance is 10 times of bubble radius, the effect of bubble interaction on bubble existence time and surface flux are about 6 and 9% changes, respectively. We conclude that if bubbles are not too small, the interactions among bubbles should be included in inert gas bubble models predicting bubble evolution.

  11. Armoring confined bubbles in concentrated colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Yu, Yingxian; Khodaparast, Sepideh; Stone, Howard

    2016-11-01

    Encapsulation of a bubble with microparticles is known to significantly improve the stability of the bubble. This phenomenon has recently gained increasing attention due to its application in a variety of technologies such as foam stabilization, drug encapsulation and colloidosomes. Nevertheless, the production of such colloidal armored bubble with controlled size and particle coverage ratio is still a great challenge industrially. We study the coating process of a long air bubble by microparticles in a circular tube filled with a concentrated microparticles colloidal suspension. As the bubble proceeds in the suspension of particles, a monolayer of micro-particles forms on the interface of the bubble, which eventually results in a fully armored bubble. We investigate the phenomenon that triggers and controls the evolution of the particle accumulation on the bubble interface. Moreover, we examine the effects of the mean flow velocity, the size of the colloids and concentration of the suspension on the dynamics of the armored bubble. The results of this study can potentially be applied to production of particle-encapsulated bubbles, surface-cleaning techniques, and gas-assisted injection molding.

  12. Soap bubbles in paintings: Art and science

    NASA Astrophysics Data System (ADS)

    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.

  13. Trauma surgery: discipline in crisis.

    PubMed

    Green, Steven M

    2009-02-01

    Throughout the past quarter century, there have been slow but dramatic changes in the nature and practice of trauma surgery, and this field increasingly faces potent economic, logistic, political, and workforce challenges. Patients and emergency physicians have much to lose by this budding crisis in our partner discipline. This article reviews the specific issues confronting trauma surgery, their historical context, and the potential directions available to this discipline. Implications of these issues for emergency physicians and for trauma care overall are discussed.

  14. Unsteady thermocapillary migration of bubbles

    NASA Technical Reports Server (NTRS)

    Dill, Loren H.; Balasubramaniam, R.

    1988-01-01

    Upon the introduction of a gas bubble into a liquid possessing a uniform thermal gradient, an unsteady thermo-capillary flow begins. Ultimately, the bubble attains a constant velocity. This theoretical analysis focuses upon the transient period for a bubble in a microgravity environment and is restricted to situations wherein the flow is sufficiently slow such that inertial terms in the Navier-Stokes equation and convective terms in the energy equation may be safely neglected (i.e., both Reynolds and Marangoni numbers are small). The resulting linear equations were solved analytically in the Laplace domain with the Prandtl number of the liquid as a parameter; inversion was accomplished numerically using a standard IMSL routine. In the asymptotic long-time limit, the theory agrees with the steady-state theory of Young, Goldstein, and Block. The theory predicts that more than 90 percent of the terminal steady velocity is achieved when the smallest dimensionless time, i.e., the one based upon the largest time scale-viscous or thermal-equals unity.

  15. Cosmological special relativity

    NASA Astrophysics Data System (ADS)

    Carmeli, M.

    1996-03-01

    Recently we presented a new special relativity theory for cosmology in which it was assumed that gravitation can be neglected and thus the bubble constant can be taken as a constant. The theory was presented in a six-dimensional hvperspace. three for the ordinary space and three for the velocities. In this paper we reduce our hyperspace to four dimensions by assuming that the three-dimensional space expands only radially, thus one is left with the three dimensions of ordinary space and one dimension of the radial velocity.

  16. Acute brain trauma

    PubMed Central

    Martin, GT

    2016-01-01

    In the 20th century, the complications of head injuries were controlled but not eliminated. The wars of the 21st century turned attention to blast, the instant of impact and the primary injury of concussion. Computer calculations have established that in the first 5 milliseconds after the impact, four independent injuries on the brain are inflicted: 1) impact and its shockwave, 2) deceleration, 3) rotation and 4) skull deformity with vibration (or resonance). The recovery, pathology and symptoms after acute brain trauma have always been something of a puzzle. The variability of these four modes of injury, along with a variable reserve of neurones, explains some of this problem. PMID:26688392

  17. Acute brain trauma.

    PubMed

    Martin, G T

    2016-01-01

    In the 20th century, the complications of head injuries were controlled but not eliminated. The wars of the 21st century turned attention to blast, the instant of impact and the primary injury of concussion. Computer calculations have established that in the first 5 milliseconds after the impact, four independent injuries on the brain are inflicted: 1) impact and its shockwave, 2) deceleration, 3) rotation and 4) skull deformity with vibration (or resonance). The recovery, pathology and symptoms after acute brain trauma have always been something of a puzzle. The variability of these four modes of injury, along with a variable reserve of neurones, explains some of this problem.

  18. Management of Pediatric Trauma.

    PubMed

    2016-08-01

    Injury is still the number 1 killer of children ages 1 to 18 years in the United States (http://www.cdc.gov/nchs/fastats/children.htm). Children who sustain injuries with resulting disabilities incur significant costs not only for their health care but also for productivity lost to the economy. The families of children who survive childhood injury with disability face years of emotional and financial hardship, along with a significant societal burden. The entire process of managing childhood injury is enormously complex and varies by region. Only the comprehensive cooperation of a broadly diverse trauma team will have a significant effect on improving the care of injured children.

  19. Trauma-focused CBT for youth with complex trauma

    PubMed Central

    Mannarino, Anthony P.; Kliethermes, Matthew; Murray, Laura A.

    2013-01-01

    Objectives Many youth develop complex trauma, which includes regulation problems in the domains of affect, attachment, behavior, biology, cognition, and perception. Therapists often request strategies for using evidence-based treatments (EBTs) for this population. This article describes practical strategies for applying Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) for youth with complex trauma. Methods TF-CBT treatment phases are described and modifications of timing, proportionality and application are described for youth with complex trauma. Practical applications include a) dedicating proportionally more of the model to the TF-CBT coping skills phase; b) implementing the TF-CBT Safety component early and often as needed throughout treatment; c) titrating gradual exposure more slowly as needed by individual youth; d) incorporating unifying trauma themes throughout treatment; and e) when indicated, extending the TF-CBT treatment consolidation and closure phase to include traumatic grief components and to generalize ongoing safety and trust. Results Recent data from youth with complex trauma support the use of the above TF-CBT strategies to successfully treat these youth. Conclusions The above practical strategies can be incorporated into TF-CBT to effectively treat youth with complex trauma. Practice implications Practical strategies include providing a longer coping skills phase which incorporates safety and appropriate gradual exposure; including relevant unifying themes; and allowing for an adequate treatment closure phase to enhance ongoing trust and safety. Through these strategies therapists can successfully apply TF-CBT for youth with complex trauma. PMID:22749612

  20. Trauma-Focused CBT for Youth with Complex Trauma

    ERIC Educational Resources Information Center

    Cohen, Judith A.; Mannarino, Anthony P.; Kliethermes, Matthew; Murray, Laura A.

    2012-01-01

    Objectives: Many youth develop complex trauma, which includes regulation problems in the domains of affect, attachment, behavior, biology, cognition, and perception. Therapists often request strategies for using evidence-based treatments (EBTs) for this population. This article describes practical strategies for applying Trauma-Focused Cognitive…

  1. Rural Trauma: Is Trauma Designation Associated with Better Hospital Outcomes?

    ERIC Educational Resources Information Center

    Bowman, Stephen M.; Zimmerman, Frederick J.; Sharar, Sam R.; Baker, Margaret W.; Martin, Diane P.

    2008-01-01

    Context: While trauma designation has been associated with lower risk of death in large urban settings, relatively little attention has been given to this issue in small rural hospitals. Purpose: To examine factors related to in-hospital mortality and delayed transfer in small rural hospitals with and without trauma designation. Methods: Analysis…

  2. Bernoulli Suction Effect on Soap Bubble Blowing?

    NASA Astrophysics Data System (ADS)

    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. Manipulating bubbles with secondary Bjerknes forces

    SciTech Connect

    Lanoy, Maxime; Derec, Caroline; Leroy, Valentin; Tourin, Arnaud

    2015-11-23

    Gas bubbles in a sound field are submitted to a radiative force, known as the secondary Bjerknes force. We propose an original experimental setup that allows us to investigate in detail this force between two bubbles, as a function of the sonication frequency, as well as the bubbles radii and distance. We report the observation of both attractive and, more interestingly, repulsive Bjerknes force, when the two bubbles are driven in antiphase. Our experiments show the importance of taking multiple scatterings into account, which leads to a strong acoustic coupling of the bubbles when their radii are similar. Our setup demonstrates the accuracy of secondary Bjerknes forces for attracting or repealing a bubble, and could lead to new acoustic tools for noncontact manipulation in microfluidic devices.

  4. Bubbles Rising Through a Soft Granular Material

    NASA Astrophysics Data System (ADS)

    Le Mestre, Robin; MacMinn, Chris; Lee, Sungyon

    2016-11-01

    Bubble migration through a soft granular material involves a strong coupling between the bubble dynamics and the deformation of the material. This is relevant to a variety of natural processes such as gas venting from sediments and gas exsolution from magma. Here, we study this process experimentally by injecting air bubbles into a quasi-2D packing of soft hydrogel beads and measuring the size, speed, and morphology of the bubbles as they rise due to buoyancy. Whereas previous work has focused on deformation resisted by intergranular friction, we focus on the previously inaccessible regime of deformation resisted by elasticity. At low confining stress, the bubbles are irregular and rounded, migrating via local rearrangement. At high confining stress, the bubbles become unstable and branched, migrating via pathway opening. The authors thank The Royal Society for support (International Exchanges Ref IE150885).

  5. BUBBLE DYNAMICS AT GAS-EVOLVING ELECTRODES

    SciTech Connect

    Sides, Paul J.

    1980-12-01

    Nucleation of bubbles, their growth by diffusion of dissolved gas to the bubble surface and by coalescence, and their detachment from the electrode are all very fast phenomena; furthermore, electrolytically generated bubbles range in size from ten to a few hundred microns; therefore, magnification and high speed cinematography are required to observe bubbles and the phenomena of their growth on the electrode surface. Viewing the action from the front side (the surface on which the bubbles form) is complicated because the most important events occur close to the surface and are obscured by other bubbles passing between the camera and the electrode; therefore, oxygen was evolved on a transparent tin oxide "window" electrode and the events were viewed from the backside. The movies showed that coalescence of bubbles is very important for determining the size of bubbles and in the chain of transport processes; growth by diffusion and by coalescence proceeds in series and parallel; coalescing bubbles cause significant fluid motion close to the electrode; bubbles can leave and reattach; and bubbles evolve in a cycle of growth by diffusion and different modes of coalescence. An analytical solution for the primary potential and current distribution around a spherical bubble in contact with a plane electrode is presented. Zero at the contact point, the current density reaches only one percent of its undisturbed value at 30 percent of the radius from that point and goes through a shallow maximum two radii away. The solution obtained for spherical bubbles is shown to apply for the small bubbles of electrolytic processes. The incremental resistance in ohms caused by sparse arrays of bubbles is given by {Delta}R = 1.352 af/kS where f is the void fraction of gas in the bubble layer, a is the bubble layer thickness, k is the conductivity of gas free electrolyte, and S is the electrode area. A densely populated gas bubble layer on an electrode was modeled as a hexagonal array of

  6. Influence of bubble size on effervescent atomization. Part 1: bubble characterization and mean spray features

    NASA Astrophysics Data System (ADS)

    Lewis, Taylor; Shepard, Thomas; Forliti, David

    2016-11-01

    In the effervescent atomization process a gas-liquid bubbly mixture is ejected from a nozzle with the goal of enhancing liquid break-up. In this work, high speed images are taken of the bubbly flow inside of an effervescent atomizer as well as downstream of the atomizer exit. The use of varying porous plate media grades and channel inserts at the air injection site of the atomizer permitted independent control of mean bubble size. Digital image analyses were used for bubble characterization and measuring mean spray features. The roles of air injection geometry on bubble population parameters inside of the effervescent atomizer are detailed. The effect of bubble size is examined at multiple gas to liquid flow rate ratios for which the bubbly flow regime was maintained. Results are presented demonstrating the influence of bubble size on the average jet width, jet dark core length, and liquid break-up.

  7. Trauma, narcissism and the two attractors in trauma.

    PubMed

    Gerzi, Shmuel

    2005-08-01

    In this paper, the author sets out to distinguish anew between two concepts that have become sorely entangled--'trauma' and 'narcissism'. Defining 'narcissism' in terms of an interaction between the selfobject and the self that maintains a protective shield, and 'trauma' as attacks on this protective shield, perpetrated by bad objects, he introduces two attractors present in trauma--'the hole attractor' and the structure enveloping it, 'the narcissistic envelope'. The hole attractor pulls the trauma patient, like a 'black hole', into a realm of emotional void, of hole object transference, devoid of memories and where often in an analyst's countertransference there are no reverberations of the trauma patient's experience. In the narcissistic envelope, on the other hand, motion, the life and death drive and fragments of memory do survive. Based on the author's own clinical experience with Holocaust survivors, and on secondary sources, the paper concludes with some clinical implications that take the two attractors into account.

  8. Bursting the bubble of melt inclusions

    USGS Publications Warehouse

    Lowenstern, Jacob B.

    2015-01-01

    Most silicate melt inclusions (MI) contain bubbles, whose significance has been alternately calculated, pondered, and ignored, but rarely if ever directly explored. Moore et al. (2015) analyze the bubbles, as well as their host glasses, and conclude that they often hold the preponderance of CO2 in the MI. Their findings entreat future researchers to account for the presence of bubbles in MI when calculating volatile budgets, saturation pressures, and eruptive flux.

  9. Collapse of vacuum bubbles in a vacuum

    SciTech Connect

    Ng, Kin-Wang; Wang, Shang-Yung

    2011-02-15

    We revisit the dynamics of a false vacuum bubble in a background de Sitter spacetime. We find that there exists a large parameter space that allows the bubble to collapse into a black hole or to form a wormhole. This may have interesting implications for the creation of a baby universe in the laboratory, the string landscape where the bubble nucleation takes place among a plenitude of metastable vacua, and the inflationary physics.

  10. Detailed Jet Dynamics in a Collapsing Bubble

    NASA Astrophysics Data System (ADS)

    Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Farhat, Mohamed

    2015-12-01

    We present detailed visualizations of the micro-jet forming inside an aspherically collapsing cavitation bubble near a free surface. The high-quality visualizations of large and strongly deformed bubbles disclose so far unseen features of the dynamics inside the bubble, such as a mushroom-like flattened jet-tip, crown formation and micro-droplets. We also find that jetting near a free surface reduces the collapse time relative to the Rayleigh time.

  11. Buoyancy Driven Shear Flows of Bubble Suspensions

    NASA Astrophysics Data System (ADS)

    Hill, R. J.; Zenit, R.; Chellppannair, T.; Koch, D. L.; Spelt, P. D. M.; Sangani, A.

    1998-11-01

    In this work the gas volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of bubble suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1 and Re >> 1 , so that the bubbles are relatively undeformed and the flow is inviscid and approximately irrotational. Nitrogen is introduced through an array of capillaries at the base of a .2x.02x2 m channel filled with an aqueous electrolyte solution (0.06 molL-1 MgSO_4). The rising bubbles generate a unidirectional shear flow, where the denser suspension at the lower surface of the channel falls, while the less dense suspension at the upper surface rises. Hot-film anemometry is used to measure the resulting gas volume fraction and fluid velocity profiles. The bubble collision rate with the sensor is related to the gas volume fraction and the mean and variance of the bubble velocity using an experimentally measured collision surface area for the sensor. Bubble collisions with the sensor are identified by the characteristic slope of the hot-film anemometer signal when bubbles collide with the sensor. It is observed that the steady shear flow develops a bubble phase pressure gradient across the channel gap as the bubbles interchange momentum through direct collisions. The discrete phase presssure gradient balances the buoyancy force driving bubbles toward the upper surface resulting in a steady void fraction profile across the gap width. The strength of the shear flow is controlled by the extent of bubble segregation and by the effective viscosity of the bubble phase. The measurements are compared with solutions of the averaged equations of motion (Kang et al. 1997; Spelt and Sangani, 1998), for a range of gas volume fractions and channel inclination angles.

  12. Bubble, Drop and Particle Unit (BDPU)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This section of the Life and Microgravity Spacelab (LMS) publication includes the following articles entitled: (1) Oscillatory Thermocapillary Instability; (2) Thermocapillary Convection in Multilayer Systems; (3) Bubble and Drop Interaction with Solidification Front; (4) A Liquid Electrohydrodynamics Experiment; (5) Boiling on Small Plate Heaters under Microgravity and a Comparison with Earth Gravity; (6) Thermocapillary Migration and Interactions of Bubbles and Drops; and (7) Nonlinear Surface Tension Driven Bubble Migration

  13. Suppression of shocked-bubble expansion due to tissue confinement with application to shock-wave lithotripsy

    PubMed Central

    Freund, Jonathan B.

    2008-01-01

    Estimates are made of the effect of tissue confinement on the response of small bubbles subjected to lithotriptor shock pressures. To do this the Rayleigh–Plesset equation, which governs the dynamics of spherical bubbles, is generalized to treat a bubble in a liquid region (blood), which is in turn encased within an elastic membrane (like a vessel’s basement membrane), beyond which a Voigt viscoelastic material models the exterior tissue. Material properties are estimated from a range of measurements available for kidneys and similar soft tissues. Special attention is given to the constitutive modeling of the basement membranes because of their expected importance due to their proximity to the bubble and their toughness. It is found that the highest expected values for the elasticity of the membrane and surrounding tissue are insufficient to suppress bubble growth. The reduced confinement of a cylindrical vessel should not alter this conclusion. Tissue viscosities taken from ultrasound measurements suppress bubble growth somewhat, though not to a degree expected to resist injury. However, the higher reported viscosities measured by other means, which are arguably more relevant to the deformations caused by growing bubbles, do indeed significantly suppress bubble expansion. PMID:18529202

  14. Some problems of the theory of bubble growth and condensation in bubble chambers

    NASA Technical Reports Server (NTRS)

    Tkachev, L. G.

    1988-01-01

    This work is an attempt to explain the reasons for the discrepancies between the theoretical and experimental values of bubble growth rate in an overheated liquid, and to provide a brief formulation of the main premises of the theory on bubble growth in liquid before making a critical analysis. To simplify the problem, the floating upward of bubbles is not discussed; moreover, the study is based on the results of the theory of the behavior of fixed bubbles.

  15. Gas Bubble Disease Monitoring and Research of Juvenile Salmonids : Annual Report 1996.

    SciTech Connect

    Maule, Alec G.; Beeman, John W.; Hans, Karen M.; Mesa, M.G.; Haner, P.; Warren, J.J.

    1997-10-01

    This document describes the project activities 1996--1997 contract year. This report is composed of three chapters which contain data and analyses of the three main elements of the project: field research to determine the vertical distribution of migrating juvenile salmonids, monitoring of juvenile migrants at dams on the Snake and Columbia rivers, and laboratory experiments to describe the progression of gas bubble disease signs leading to mortality. The major findings described in this report are: A miniature pressure-sensitive radio transmitter was found to be accurate and precise and, after compensation for water temperature, can be used to determine the depth of tagged-fish to within 0.32 m of the true depth (Chapter 1). Preliminary data from very few fish suggest that depth protects migrating juvenile steelhead from total dissolved gas supersaturation (Chapter 1). As in 1995, few fish had any signs of gas bubble disease, but it appeared that prevalence and severity increased as fish migrated downstream and in response to changing gas supersaturation (Chapter 2). It appeared to gas bubble disease was not a threat to migrating juvenile salmonids when total dissolved gas supersaturation was < 120% (Chapter 2). Laboratory studies suggest that external examinations are appropriate for determining the severity of gas bubble disease in juvenile salmonids (Chapter 3). The authors developed a new method for examining gill arches for intravascular bubbles by clamping the ventral aorta to reduce bleeding when arches were removed (Chapter 3). Despite an outbreak of bacterial kidney disease in the experimental fish, the data indicate that gas bubble disease is a progressive trauma that can be monitored (Chapter 3).

  16. Single-bubble sonoluminescence from noble gases.

    PubMed

    Yasui, K

    2001-03-01

    Single-bubble sonoluminescence (SBSL) from noble gases in water is studied theoretically in order to clarify the reason of the distinguished feature that the luminescence is strong for all noble gases, while the other systems of cavitation luminescence are greatly enhanced by the presence of the heavy noble gas(xenon). It is clarified that in spite of the larger thermal conductivity of lighter noble gases the maximum temperature in a SBSL bubble of lighter noble gases is higher due both to the segregation of water vapor and noble gas inside a SBSL bubble and the stronger acoustic drive of a SBSL bubble of lighter noble gases.

  17. Single-bubble sonoluminescence from noble gases

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    2001-03-01

    Single-bubble sonoluminescence (SBSL) from noble gases in water is studied theoretically in order to clarify the reason of the distinguished feature that the luminescence is strong for all noble gases, while the other systems of cavitation luminescence are greatly enhanced by the presence of the heavy noble gas(xenon). It is clarified that in spite of the larger thermal conductivity of lighter noble gases the maximum temperature in a SBSL bubble of lighter noble gases is higher due both to the segregation of water vapor and noble gas inside a SBSL bubble and the stronger acoustic drive of a SBSL bubble of lighter noble gases.

  18. Spectroscopic characteristic of conical bubble luminescence

    NASA Astrophysics Data System (ADS)

    Chen, Qi-Dai; Fu, Li-Min; Ai, Xi-Cheng; Zhang, Jian-Ping; Wang, Long

    2005-04-01

    The conical bubble sonoluminescence (CBSL) from the collapse of the bubble was observed in an improved U-tube apparatus. The emitted light energy of a single CBSL flash was measured to be ~ 1.4mJ. The pulse width was about 100μs. The spectra of luminescence were continuum superimposed with the spectral bands from the excited-state C2, CN and CH. The CBSL provides a link between the light emission of the single-bubble and the multi-bubble sonoluminescence (SBSL and MBSL).

  19. Multiple Spark-Generated Bubble Interactions

    NASA Astrophysics Data System (ADS)

    Khoo, Boo Cheong; Adikhari, Deepak; Fong, Siew Wan; Klaseboer, Evert

    The complex interactions of two and three spark-generated bubbles are studied using high speed photography. The corresponding simulations are performed using a 3D Boundary Element Method (BEM) code. The bubbles generated are between 3 to 5 mm in radius, and they are either in-phase or out-of-phase with one another. The possible interaction phenomena between two identically sized bubbles are summarized. Depending on their relative distances and phase differences, they can coalesce, jet towards or away from one another, split into smaller bubbles, or 'catapult' away from one another. The 'catapult' effect can be utilized to generated high speed jet in the absence of a solid boundary or shockwave. Also three bubble interactions are highlighted. Complicated phenomena such as bubble forming an elliptical shape and bubble splitting are observed. The BEM simulations provide insight into the physics of the phenomena by providing details such as detailed bubble shape changes (experimental observations are limited by the temporal and spatial resolution), and jet velocity. It is noted that the well-tested BEM code [1,2] utilized here is computationally very efficient as compared to other full-domain methods since only the bubble surface is meshed.

  20. Analysis of a deflating soap bubble

    NASA Astrophysics Data System (ADS)

    Jackson, David P.; Sleyman, Sarah

    2010-10-01

    A soap bubble on the end of a cylindrical tube is seen to deflate as the higher pressure air inside the bubble escapes through a tube. We perform an experiment to measure the radius of the slowly deflating bubble and observe that the radius decreases to a minimum before quickly increasing. This behavior reflects the fact that the bubble ends up as a flat surface over the end of the tube. A theoretical analysis reproduces this behavior and compares favorably with the experimental data.

  1. Band gaps in bubble phononic crystals

    NASA Astrophysics Data System (ADS)

    Leroy, V.; Bretagne, A.; Lanoy, M.; Tourin, A.

    2016-12-01

    We investigate the interaction between Bragg and hybridization effects on the band gap properties of bubble phononic crystals. These latter consist of air cavities periodically arranged in an elastomer matrix and are fabricated using soft-lithography techniques. Their transmission properties are affected by Bragg effects due to the periodicity of the structure as well as hybridization between the propagating mode of the embedding medium and bubble resonance. The hybridization gap survives disorder while the Bragg gap requires a periodic distribution of bubbles. The distance between two bubble layers can be tuned to make the two gaps overlap or to create a transmission peak in the hybridization gap.

  2. Electrolytic Bubble Growth on Pillared Arrays

    NASA Astrophysics Data System (ADS)

    Lee, Kenneth; Savas, Omer

    2013-11-01

    In current energy research, artificial photosynthetic (AP) devices are being designed to split water and harvest hydrogen gas using sunlight. In one such design, hydrogen gas bubbles evolve on catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system - all of which deteriorate device performance. Therefore, understanding how to remove evolved gas bubbles from the pillar surfaces is crucial. Flow visualization of electrolytic bubble nucleation and detachment from the catalytic pillar surfaces has been conducted. The bubble departure diameter and lift-off frequency are extracted and compared with known correlations from boiling heat transfer. Bubble tracking indicates that bubble detachment is enhanced by local interactions with neighboring bubbles. These observations suggest how hydrogen gas bubbles can be effectively removed from pillared surfaces to prolong AP device longevity. Joint Center for Artificial Photosynthesis, a U.S. Department of Energy (DOE) Energy Innovations Hub.

  3. Sound waves in multifractional liquids with bubbles

    NASA Astrophysics Data System (ADS)

    Gubaidullin, D. A.; Gafiyatov, R. N.

    2017-01-01

    The propagation of sound waves in multifractional mixtures of liquid with vapor–gas and gas bubbles of different sizes and different compositions with phase transitions is studied. The dispersed phase consists of N+M fractions having various gases in bubbles and different in the bubbles radii. Phase transitions accounted for N fractions. The total bubble volume concentration is small (less than 1%). The dispersion relation is derived and dispersion curves is built. The evolution of the weak pulsed perturbations of the pressure in this mixture was calculated numerically.

  4. Bubble formation in additive manufacturing of glass

    NASA Astrophysics Data System (ADS)

    Luo, Junjie; Gilbert, Luke J.; Peters, Daniel C.; Bristow, Douglas A.; Landers, Robert G.; Goldstein, Jonathan T.; Urbas, Augustine M.; Kinzel, Edward C.

    2016-05-01

    Bubble formation is a common problem in glass manufacturing. The spatial density of bubbles in a piece of glass is a key limiting factor to the optical quality of the glass. Bubble formation is also a common problem in additive manufacturing, leading to anisotropic material properties. In glass Additive Manufacturing (AM) two separate types of bubbles have been observed: a foam layer caused by the reboil of the glass melt and a periodic pattern of bubbles which appears to be unique to glass additive manufacturing. This paper presents a series of studies to relate the periodicity of bubble formation to part scan speed, laser power, and filament feed rate. These experiments suggest that bubbles are formed by the reboil phenomena why periodic bubbles result from air being trapped between the glass filament and the substrate. Reboil can be detected using spectroscopy and avoided by minimizing the laser power while periodic bubbles can be avoided by a two-step laser melting process to first establish good contact between the filament and substrate before reflowing the track with higher laser power.

  5. Stationary bubble formation and cavity collapse in wedge-shaped hoppers

    PubMed Central

    Yagisawa, Yui; Then, Hui Zee; Okumura, Ko

    2016-01-01

    The hourglass is one of the apparatuses familiar to everyone, but reveals intriguing behaviors peculiar to granular materials, and many issues are remained to be explored. In this study, we examined the dynamics of falling sand in a special form of hourglass, i.e., a wedge-shaped hopper, when a suspended granular layer is stabilized to a certain degree. As a result, we found remarkably different dynamic regimes of bubbling and cavity. In the bubbling regime, bubbles of nearly equal size are created in the sand at a regular time interval. In the cavity regime, a cavity grows as sand beads fall before a sudden collapse of the cavity. Bubbling found here is quite visible to a level never discussed in the physics literature and the cavity regime is a novel phase, which is neither continuous, intermittent nor completely blocked phase. We elucidate the physical conditions necessary for the bubbling and cavity regimes and develop simple theories for the regimes to successfully explain the observed phenomena by considering the stability of a suspended granular layer and clogging of granular flow at the outlet of the hopper. The bubbling and cavity regimes could be useful for mixing a fluid with granular materials. PMID:27138747

  6. Dynamics of Vapour Bubbles in Nucleate Boiling. 1; Basic Equations of Bubble Evolution

    NASA Technical Reports Server (NTRS)

    Buyevich, Yu A.; Webbon, Bruce W.; Callaway, Robert (Technical Monitor)

    1995-01-01

    We consider the behaviour of a vapour bubble formed at a nucleation site on a heated horizontal wall. There is no forced convection of an ambient liquid, and the bubble is presumably separated from the wall by a thin liquid microlayer. The energy conservation law results in a variational equation for the mechanical energy of the whole system consisting of the bubble and liquid. It leads to a set of two strongly nonlinear equations which govern bubble expansion and motion of its centre of mass. A supplementary equation to find out the vapour temperature follows from consideration of heat transfer to the bubble, both from the bulk of surrounding liquid and through the microlayer. The average thickness of the microlayer is shown to increase monotonously with time as the bubble meniscus spreads along the wall. Bubble expansion is driven by the pressure head between vapour inside and liquid far away from the bubble, with due allowance for surface tension and gravity effects. It is resisted by inertia of liquid being placed into motion as the bubble grows. The inertia originates also a force that presses the bubble to the wall. This force is counteracted by the buoyancy and an effective surface tension force that tends to transform the bubble into a sphere. The analysis brings about quite a new formulation of the familiar problem of bubble growth and detachment under conditions of nucleate pool boiling.

  7. Sexual Trauma, Spirituality, and Psychopathology

    ERIC Educational Resources Information Center

    Krejci, Mark J.; Thompson, Kevin M.; Simonich, Heather; Crosby, Ross D.; Donaldson, Mary Ann; Wonderlich, Stephen A.; Mitchell, James E.

    2004-01-01

    This study assessed the association between spirituality and psychopathology in a group of sexual abuse victims and controls with a focus on whether spirituality moderated the association between sexual trauma and psychopathology. Seventy-one sexual trauma victims were compared to 25 control subjects on spiritual well-being, the Eating Disorder…

  8. Occlusal trauma--periodontal concerns.

    PubMed

    Hallmon, W W

    2001-10-01

    While there is evidence that suggests that occlusal trauma is a risk factor for periodontal destruction, there is no evidence that indicates that occlusal trauma will initiate periodontal destruction. Effective plaque control and compliance with periodontal maintenance recommendations are key and essential factors necessary to assure successful treatment and control of periodontal disease.

  9. Potential uses of vacuum bubbles in noise and vibration control

    NASA Technical Reports Server (NTRS)

    Ver, Istvan L.

    1989-01-01

    Vacuum bubbles are new acoustic elements which are dynamically more compliant than the gas volume they replace, but which are statically robust. They are made of a thin metallic shell with vacuum in their cavity. Consequently, they pose no danger in terms of contamination or fire hazard. The potential of the vacuum bubble concept for noise and vibration control was assessed with special emphases on spacecraft and aircraft applications. The following potential uses were identified: (1) as a cladding, to reduce sound radiation of vibrating surfaces and the sound excitation of structures, (2) as a screen, to reflect or absorb an incident sound wave, and (3) as a liner, to increase low frequency sound transmission loss of double walls and to increase the low frequency sound attenuation of muffler baffles. It was found that geometric and material parameters must be controlled to a very high accuracy to obtain optimal performance and that performance is highly sensitive to variations in static pressure. Consequently, it was concluded that vacuum bubbles have more potential in spacecraft applications where static pressure is controlled more than in aircraft applications where large fluctuations in static pressure are common.

  10. Bubble dynamics under acoustic excitation with multiple frequencies

    NASA Astrophysics Data System (ADS)

    Zhang, Y. N.; Zhang, Y. N.; Li, S. C.

    2015-01-01

    Because of its magnificent mechanical and chemical effects, acoustic cavitation plays an important role in a broad range of biomedical, chemical and mechanical engineering problems. Particularly, irradiation of the multiple frequency acoustic wave could enhance the effects of cavitation. The advantages of employment of multi-frequency ultrasonic field include decreasing the cavitation thresholds, promoting cavitation nuclei generation, increasing the mass transfer and improving energy efficiency. Therefore, multi-frequency ultrasonic systems are employed in a variety of applications, e.g., to enhance the intensity of sonoluminenscence, to increase efficiency of sonochemical reaction, to improve the accuracy of ultrasound imaging and the efficiency of tissue ablation. Compared to single-frequency systems, a lot of new features of bubble dynamics exist in multi-frequency systems, such as special properties of oscillating bubbles, unique resonances in the bubble response curves, and unusual chaotic behaviours. In present paper, the underlying mechanisms of the cavitation effects under multi-frequency acoustical excitation are also briefly introduced.

  11. Molecular dynamics simulations of He bubble nucleation at grain boundaries

    SciTech Connect

    Yongfeng Zhang; Paul C Millett; Michael Tonks; Liangzhe Zhang; Bulent Biner

    2012-08-01

    The nucleation behavior of He bubbles in nano-grained body-centered-cubic (BCC) Mo is simulated using molecular dynamics (MD) simulations with a bicrystal model, focusing on the effect of grain boundary (GB) structure. Three types of GBs, the (100) twist S29, the ?110? symmetrical tilt (tilt angle of 10.1?), and the (112) twin boundaries, are studied as representatives of random GB, low angle GB with misfit dislocations, and special sigma boundaries. With the same amount of He, more He clusters form in nano-grained Mo with smaller average size compared to that in bulk. The effects of the GB structure originate from the excess volume in GBs. Trapping by excess volume results in reduction in mobility of He atoms, which enhances the nucleation with higher density of bubbles, and impedes the growth of He bubbles by absorption of mobile He atoms. Furthermore, the distribution of excess volume in GBs determines the distribution of He clusters. The effect of GBs becomes less pronounced with increasing vacancy concentration in the matrix.

  12. Prehospital Trauma Care in Singapore.

    PubMed

    Ho, Andrew Fu Wah; Chew, David; Wong, Ting Hway; Ng, Yih Yng; Pek, Pin Pin; Lim, Swee Han; Anantharaman, Venkataraman; Hock Ong, Marcus Eng

    2015-01-01

    Prehospital emergency care in Singapore has taken shape over almost a century. What began as a hospital-based ambulance service intended to ferry medical cases was later complemented by an ambulance service under the Singapore Fire Brigade to transport trauma cases. The two ambulance services would later combine and come under the Singapore Civil Defence Force. The development of prehospital care systems in island city-state Singapore faces unique challenges as a result of its land area and population density. This article defines aspects of prehospital trauma care in Singapore. It outlines key historical milestones and current initiatives in service, training, and research. It makes propositions for the future direction of trauma care in Singapore. The progress Singapore has made given her circumstances may serve as lessons for the future development of prehospital trauma systems in similar environments. Key words: Singapore; trauma; prehospital emergency care; emergency medical services.

  13. Colorful Demos with a Long-Lasting Soap Bubble.

    ERIC Educational Resources Information Center

    Behroozi, F.; Olson, D. W.

    1994-01-01

    Describes several demonstrations that feature interaction of light with soap bubbles. Includes directions about how to produce a long-lasting stationary soap bubble with an easily changeable size and describes the interaction of white light with the bubble. (DDR)

  14. Spherically symmetric conformal gravity and ''gravitational bubbles''

    SciTech Connect

    Berezin, V.A.; Dokuchaev, V.I.; Eroshenko, Yu.N. E-mail: dokuchaev@inr.ac.ru

    2016-01-01

    The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the ''gravitational bubbles'', which is compact and with zero Weyl tensor. Thus, we obtained the pure vacuum curved space-times (without any material sources, including the cosmological constant) what is absolutely impossible in General Relativity. Such a phenomenon makes it easier to create the universe from ''nothing''. The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly some features of non-vacuum solutions. Two of them are explicitly written, namely, the metrics à la Vaidya, and the electrovacuum space-time metrics.

  15. Spherically symmetric conformal gravity and ``gravitational bubbles''

    NASA Astrophysics Data System (ADS)

    Berezin, V. A.; Dokuchaev, V. I.; Eroshenko, Yu. N.

    2016-01-01

    The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the ``gravitational bubbles'', which is compact and with zero Weyl tensor. Thus, we obtained the pure vacuum curved space-times (without any material sources, including the cosmological constant) what is absolutely impossible in General Relativity. Such a phenomenon makes it easier to create the universe from ``nothing''. The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly some features of non-vacuum solutions. Two of them are explicitly written, namely, the metrics à la Vaidya, and the electrovacuum space-time metrics.

  16. Magma mixing enhanced by bubble segregation

    NASA Astrophysics Data System (ADS)

    Wiesmaier, S.; Morgavi, D.; Renggli, C.; Perugini, D.; De Campos, C. P.; Hess, K.-U.; Ertel-Ingrisch, W.; Lavallée, Y.; Dingwell, D. B.

    2015-04-01

    That rising bubbles may significantly affect magma mixing paths has already been demon strated by analogue experiments. Here, for the first time, bubble-advection experiments are performed employing volcanic melts at magmatic temperatures. Cylinders of basaltic glass were placed below cylinders of rhyolite glass. Upon melting, interstitial air formed bubbles that rose into the rhyolite melt, thereby entraining tails of basaltic liquid. The formation of plume-like filaments of advected basalt within the rhyolite was characterized by microCT and subsequent high-resolution EMP analyses. Melt entrainment by bubble ascent appears to be an efficient mechanism for mingling volcanic melts of highly contrasting compositions and properties. MicroCT imaging reveals bubbles trailing each other and multiple filaments coalescing into bigger ones. Rheological modelling of the filaments yields viscosities of up to 2 orders of magnitude lower than for the surrounding rhyolitic liquid. Such a viscosity contrast implies that bubbles rising successively are likely to follow this pathway of low resistance that previously ascending bubbles have generated. Filaments formed by multiple bubbles would thus experience episodic replenishment with mafic material. Inevitable implications for the concept of bubble advection in magma mixing include thereby both an acceleration of mixing because of decreased viscous resistance for bubbles inside filaments and non-conventional diffusion systematics because of intermittent supply of mafic material (instead of a single pulse) inside a material. Inside the filaments, the mafic material was variably hybridised to andesitic through rhyolitic composition. Compositional profiles alone are ambiguous, however, to determine whether single or multiple bubbles were involved during formation of a filament. Statistical analysis, employing concentration variance as measure of homogenisation, demonstrates that also filaments appearing as single-bubble filaments

  17. Neural basis of economic bubble behavior.

    PubMed

    Ogawa, A; Onozaki, T; Mizuno, T; Asamizuya, T; Ueno, K; Cheng, K; Iriki, A

    2014-04-18

    Throughout human history, economic bubbles have formed and burst. As a bubble grows, microeconomic behavior ceases to be constrained by realistic predictions. This contradicts the basic assumption of economics that agents have rational expectations. To examine the neural basis of behavior during bubbles, we performed functional magnetic resonance imaging while participants traded shares in a virtual stock exchange with two non-bubble stocks and one bubble stock. The price was largely deflected from the fair price in one of the non-bubble stocks, but not in the other. Their fair prices were specified. The price of the bubble stock showed a large increase and battering, as based on a real stock-market bust. The imaging results revealed modulation of the brain circuits that regulate trade behavior under different market conditions. The premotor cortex was activated only under a market condition in which the price was largely deflected from the fair price specified. During the bubble, brain regions associated with the cognitive processing that supports order decisions were identified. The asset preference that might bias the decision was associated with the ventrolateral prefrontal cortex and the dorsolateral prefrontal cortex (DLPFC). The activity of the inferior parietal lobule (IPL) was correlated with the score of future time perspective, which would bias the estimation of future price. These regions were deemed to form a distinctive network during the bubble. A functional connectivity analysis showed that the connectivity between the DLPFC and the IPL was predominant compared with other connectivities only during the bubble. These findings indicate that uncertain and unstable market conditions changed brain modes in traders. These brain mechanisms might lead to a loss of control caused by wishful thinking, and to microeconomic bubbles that expand, on the macroscopic scale, toward bust.

  18. [Advanced Trauma Life Support (ATLS) in the emergency room. Is it suitable as an SOP?].

    PubMed

    Shafizadeh, S; Tjardes, T; Steinhausen, E; Balke, M; Paffrath, T; Bouillon, B; Bäthis, H

    2010-08-01

    There is clinical evidence that a standardized management of trauma patients in the emergency room improves outcome. ATLS is a training course that teaches a systematic approach to the trauma patient in the emergency room. The aims are a rapid and accurate assessment of the patient's physiologic status, treatment according to priorities, and making decisions on whether the local resources are sufficient for adequate definitive treatment of the patient or if transfer to a trauma center is necessary. Above all it is important to prevent secondary injury, to realize timing as a relevant factor in the initial treatment, and to assure a high standard of care. A standard operating procedure (SOP) exactly regulates the approach to trauma patients and determines the responsibilities of the involved faculties. An SOP moreover incorporates the organizational structure in the treatment of trauma patients as well as the necessary technical equipment and staff requirements. To optimize process and result quality, priorities are in the fields of medical fundamentals of trauma care, education, and fault management. SOPs and training courses increase the process and result quality in the treatment of the trauma patient in the emergency room. These programs should be based on the special demands of the physiology of the trauma as well as the structural specifics of the hospital. ATLS does not equal an SOP but it qualifies as a standardized concept for management of trauma patients in the emergency room.

  19. Trauma and religiousness.

    PubMed

    Gostečnik, Christian; Repič Slavič, Tanja; Lukek, Saša Poljak; Cvetek, Robert

    2014-06-01

    Victims of traumatic events who experience re-traumatization often develop a highly ambivalent relationship to God and all religiosity as extremely conflictual. On the one hand, they may choose to blame God for not having protected them, for having left them to feel so alone, for having been indifferent to them or they may even turn their wrath upon God, as the source of cruelty. Often though, the traumas experienced by individuals prompt them to turn to God and religion in search of help. This gives reason for the need of new and up-to-date research that can help elucidate why some people choose to seek help in religion and others turn away from it.

  20. Vascular trauma historical notes.

    PubMed

    Rich, Norman M

    2011-03-01

    This article provides a brief historical review of treatment of vascular trauma. Although methods for ligation came into use in the second century, this knowledge was lost during the Dark Ages and did not come back until the Renaissance. Many advances in vascular surgery occurred during the Balkan Wars, World War I, and World War II, although without antibiotics and blood banking, the philosophy of life over limb still ruled. Documenting and repairing both arteries and veins became more common during the Korean and Vietnam conflicts. Increased documentation has revealed that the current conflicts have resulted in more arterial injuries than in previous wars, likely because of improved body armor, improvised explosive device attacks, tourniquet use, and improved medical evacuation time. This brief review emphasizes the great value of mentorship and the legacy of the management of arterial and venous injuries to be passed on.

  1. Orthopedic trauma in pregnancy.

    PubMed

    Desai, Pratik; Suk, Michael

    2007-11-01

    Trauma sustained during pregnancy can trigger uncertainty and anxiety for patient and orthopedic surgeon alike. In particular, orthopedic-related injuries raise concerns about preoperative, intraoperative, and postoperative care. In this article, we review common concerns about radiation exposure, leukemia, pain management, anticoagulation, and anesthesia. One finding is that radiation risk is minimal when obtaining x-rays for operative planning, provided that the cumulative dose is within 5 rad. We also address safety concerns about patient positioning and staff radiation exposure. In addition, we found that most anesthetics used in pregnancy are category C (ie, safe). Perioperative opioid use for pain management is recommended with little risk. Regarding anticoagulation, low-molecular-weight heparin and fondaparinux are the safest choices. Last, pregnancy is not a contraindication to operative management of pelvic and acetabular fractures.

  2. Lightweight Trauma Module - LTM

    NASA Technical Reports Server (NTRS)

    Hatfield, Thomas

    2008-01-01

    Current patient movement items (PMI) supporting the military's Critical Care Air Transport Team (CCATT) mission as well as the Crew Health Care System for space (CHeCS) have significant limitations: size, weight, battery duration, and dated clinical technology. The LTM is a small, 20 lb., system integrating diagnostic and therapeutic clinical capabilities along with onboard data management, communication services and automated care algorithms to meet new Aeromedical Evacuation requirements. The Lightweight Trauma Module is an Impact Instrumentation, Inc. project with strong Industry, DoD, NASA, and Academia partnerships aimed at developing the next generation of smart and rugged critical care tools for hazardous environments ranging from the battlefield to space exploration. The LTM is a combination ventilator/critical care monitor/therapeutic system with integrated automatic control systems. Additional capabilities are provided with small external modules.

  3. Penetrating neck traumas

    PubMed Central

    Kaczmarski, Jacek; Brzeziński, Daniel; Cieślik-Wolski, Bartosz; Kozak, Józef

    2014-01-01

    Aim of the study Aim of the study is to present our own experiences in the treatment of people suffering from penetrating neck traumas. Material and methods In the years 1996-2012, 10 patients with penetrating neck traumas were treated, including 3 women and 7 men. The patients’ age ranged from 16 to 55 (the average age being 40.7 years). In 9 cases the wound was caused by cutting or stabbing, while in one case it was inflicted by a gunshot. In 8 patients it was a single cut wound, while one patient suffered from 34 stab wounds to the neck, chest and stomach. Two cut wounds resulted from a suicide attempt. The remaining injuries were the result of a crime. Results All patients underwent immediate surgery, which involved revision of the neck wounds in 8 cases, one longitudinal sternotomy and one left-sided thoracotomy. The indications for surgery included increased subcutaneous emphysema in 5 patients, bleeding from the wound in 3 patients, and mediastinal hematoma in 2 patients. The damage assessed intraoperatively included tracheal damage in 6 patients, damage to carotid vessels in 3 patients, larynx in 2 patients, thoracic vessels in 2 patients, oesophagus in 1 patient and thyroid gland in 1 patient. In 9 patients, the treatment yielded positive results. The patient with a gunshot wound died during the surgery due to massive bleeding from the aorta. Conclusions In patients with penetrating neck wounds, early and rapid diagnostics allows one to determine the indications for surgery and prevent serious fatal complications. PMID:26336390

  4. Cavitation inception from bubble nuclei

    PubMed Central

    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

  5. Cavitation inception from bubble nuclei.

    PubMed

    Mørch, K A

    2015-10-06

    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.

  6. Dynamics of Vapour Bubbles in Nucleate Boiling. 2; Evolution of Thermally Controlled Bubbles

    NASA Technical Reports Server (NTRS)

    Buyevich, Yu A.; Webbon, Bruce W.; Callaway, Robert (Technical Monitor)

    1995-01-01

    The previously developed dynamic theory of growth and detachment of vapour bubbles under conditions of nucleate pool boiling is applied to study motion and deformation of a bubble evolving at a single nucleation site. The bubble growth is presumed to be thermally controlled, and two components of heat transfer to the bubble are accounted of: the one from the bulk of surrounding liquid and the one due to heat conduction across a liquid microlayer formed underneath the bubble. Bubble evolution is governed by the buoyancy and an effective surface tension force, both the forces making the bubble centre of mass move away from the wall and, thus, assisting its detachment. Buoyancy-controlled and surface-tension-controlled regimes are considered separately in a meticulous way. The duration of the whole process of bubble evolution till detachment, the rate of growth, and the bubble departure size are found as functions of time and physical and operating parameters. Some repeatedly observed phenomena, such as an influence of gravity on the growth rate, are explained. Inferences of the model agree qualitatively with available experimental evidence, and conclusions pertaining to the dependence on gravity of the bubble radius at detachment and the whole time of the bubble development when being attached to the wall are confirmed quantitatively.

  7. Measurement of Bubble Size Distribution Based on Acoustic Propagation in Bubbly Medium

    NASA Astrophysics Data System (ADS)

    Wu, Xiongjun; Hsiao, Chao-Tsung; Choi, Jin-Keun; Chahine, Georges

    2013-03-01

    Acoustic properties are strongly affected by bubble size distribution in a bubbly medium. Measurement of the acoustic transmission becomes increasingly difficulty as the void fraction of the bubbly medium increases due to strong attenuation, while acoustic reflection can be measured more easily with increasing void fraction. The ABS ACOUSTIC BUBBLE SPECTROMETER®\\copyright, an instrument for bubble size measurement that is under development tries to take full advantage of the properties of acoustic propagation in bubbly media to extract bubble size distribution. Properties of both acoustic transmission and reflection in the bubbly medium from a range of short single-frequency bursts of acoustic waves at different frequencies are measured in an effort to deduce the bubble size distribution. With the combination of both acoustic transmission and reflection, assisted with validations from photography, the ABS ACOUSTIC BUBBLE SPECTROMETER®\\copyright has the potential to measure bubble size distributions in a wider void fraction range. This work was sponsored by Department of Energy SBIR program

  8. New approaches to hard bubble suppression

    NASA Technical Reports Server (NTRS)

    Henry, R. D.; Besser, P. J.; Warren, R. G.; Whitcomb, E. C.

    1973-01-01

    Description of a new double-layer method for the suppression of hard bubbles that is more versatile than previously reported suppression techniques. It is shown that it may be possible to prevent hard bubble generation without recourse to exchange coupling of multilayer films.

  9. Simple improvements to classical bubble nucleation models

    NASA Astrophysics Data System (ADS)

    Tanaka, Kyoko K.; Tanaka, Hidekazu; Angélil, Raymond; Diemand, Jürg

    2015-08-01

    We revisit classical nucleation theory (CNT) for the homogeneous bubble nucleation rate and improve the classical formula using a correct prefactor in the nucleation rate. Most of the previous theoretical studies have used the constant prefactor determined by the bubble growth due to the evaporation process from the bubble surface. However, the growth of bubbles is also regulated by the thermal conduction, the viscosity, and the inertia of liquid motion. These effects can decrease the prefactor significantly, especially when the liquid pressure is much smaller than the equilibrium one. The deviation in the nucleation rate between the improved formula and the CNT can be as large as several orders of magnitude. Our improved, accurate prefactor and recent advances in molecular dynamics simulations and laboratory experiments for argon bubble nucleation enable us to precisely constrain the free energy barrier for bubble nucleation. Assuming the correction to the CNT free energy is of the functional form suggested by Tolman, the precise evaluations of the free energy barriers suggest the Tolman length is ≃0.3 σ independently of the temperature for argon bubble nucleation, where σ is the unit length of the Lennard-Jones potential. With this Tolman correction and our prefactor one gets accurate bubble nucleation rate predictions in the parameter range probed by current experiments and molecular dynamics simulations.

  10. The Minnaert Bubble: An Acoustic Approach

    ERIC Educational Resources Information Center

    Devaud, Martin; Hocquet, Thierry; Bacri, Jean-Claude; Leroy, Valentin

    2008-01-01

    We propose an "ab initio" introduction to the well-known Minnaert pulsating bubble at graduate level. After a brief recall of the standard stuff, we begin with a detailed discussion of the radial movements of an air bubble in water. This discussion is managed from an acoustic point of view, and using the Lagrangian rather than the Eulerian…

  11. Steady State Vapor Bubble in Pool Boiling

    PubMed Central

    Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.

    2016-01-01

    Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics. PMID:26837464

  12. Air bubble bursting effect of lotus leaf.

    PubMed

    Wang, Jingming; Zheng, Yongmei; Nie, Fu-Qiang; Zhai, Jin; Jiang, Lei

    2009-12-15

    In this paper, a phenomenon of air bubbles quickly bursting within several milliseconds on a "self-cleaning" lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar air bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of air bubble bursting. Air bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, air bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect air bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae, the width and spacing were significant for air bubble bursting. An original model was proposed to further evaluate the reason why the micro/nano hierarchical rough structures had an excellent air bubble bursting effect, and the validity of the model was theoretically demonstrated.

  13. Continuous-data FIFO bubble shift register

    NASA Technical Reports Server (NTRS)

    Chen, T. T.

    1977-01-01

    Simple loop first-in-first-out (FIFO) bubble memory shift register has continuous storage capability. Bubble shift register simplifies chip-control electronics by enabling all control functions to be alined at same bit. FIFO shift register is constructed from passive replicator and annihilator combinations.

  14. Videotaping the Lifespan of a Soap Bubble.

    ERIC Educational Resources Information Center

    Ramme, Goran

    1995-01-01

    Describes how the use of a videotape to record the history of a soap bubble allows a study of many interesting events in considerable detail including interference fringes, convection and turbulence patterns on the surface, formation of black film, and the ultimate explosion of the bubble. (JRH)

  15. Drops and Bubble in Materials Science

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1982-01-01

    The formation of extended p-n junctions in semiconductors by drop migration, mechanisms and morphologies of migrating drops and bubbles in solids and nucleation and corrections to the Volmer-Weber equations are discussed. Bubble shrinkage in the processing of glass, the formation of glass microshells as laser-fusion targets, and radiation-induced voids in nuclear reactors were examined.

  16. The Physics of Foams, Droplets and Bubbles

    ERIC Educational Resources Information Center

    Sarker, Dipak K.

    2013-01-01

    Foams or bubble dispersions are common to milkshakes, bread, champagne froth, shaving mousse, shampoo, crude oil extraction systems, upholstery packing and bubble wrap, whereas the term droplet is often synonymous with either a small drop of water or a drop of oil--a type of coarse dispersion. The latter are seen in butter and milk, household…

  17. Measuring the surface tension of soap bubbles

    NASA Technical Reports Server (NTRS)

    Sorensen, Carl D.

    1992-01-01

    The objectives are for students to gain an understanding of surface tension, to see that pressure inside a small bubble is larger than that inside a large bubble. These concepts can be used to explain the behavior of liquid foams as well as precipitate coarsening and grain growth. Equipment, supplies, and procedures are explained.

  18. Acoustic-Induced Drag on a Bubble.

    DTIC Science & Technology

    1999-03-01

    possibly controlling bubble migration and heat transfer. 14. SUBJECT TERMS: Drag, bubble dynamics, analog to stochastic electrodynamics 15. NUMBER OF...remains constant. The notion that acoustic noise can test, by analogy, predictions due to stochastic electrodynamics and to ZPF effects has been

  19. Structure of nanoscale gas bubbles in metals

    SciTech Connect

    Caro, A. Schwen, D.; Martinez, E.

    2013-11-18

    A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2γ/R, with γ the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1 nm and below.

  20. Steady State Vapor Bubble in Pool Boiling.

    PubMed

    Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C; Maroo, Shalabh C

    2016-02-03

    Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.

  1. Gravity Wave Seeding of Equatorial Plasma Bubbles

    NASA Technical Reports Server (NTRS)

    Singh, Sardul; Johnson, F. S.; Power, R. A.

    1997-01-01

    Some examples from the Atmosphere Explorer E data showing plasma bubble development from wavy ion density structures in the bottomside F layer are described. The wavy structures mostly had east-west wavelengths of 150-800 km, in one example it was about 3000 km. The ionization troughs in the wavy structures later broke up into either a multiple-bubble patch or a single bubble, depending upon whether, in the precursor wavy structure, shorter wavelengths were superimposed on the larger scale wavelengths. In the multiple bubble patches, intrabubble spacings vaned from 55 km to 140 km. In a fully developed equatorial spread F case, east-west wavelengths from 690 km down to about 0.5 km were present simultaneously. The spacings between bubble patches or between bubbles in a patch appear to be determined by the wavelengths present in the precursor wave structure. In some cases, deeper bubbles developed on the western edge of a bubble patch, suggesting an east-west asymmetry. Simultaneous horizontal neutral wind measurements showed wavelike perturbations that were closely associated with perturbations in the plasma horizontal drift velocity. We argue that the wave structures observed here that served as the initial seed ion density perturbations were caused by gravity waves, strengthening the view that gravity waves seed equatorial spread F irregularities.

  2. Bubbling at high flow rates in inviscid and viscous liquids (slags)

    NASA Astrophysics Data System (ADS)

    Engh, T. Abel; Nilmani, M.

    1988-02-01

    The behavior of gas discharging into melts at high velocities but still in the bubbling regime has been investigated in a laboratory modeling study for constant flow conditions. Air or helium was injected through a vertical tuyere into water, zinc-chloride, and aqueous glycerol solutions. High speed cinematography and pressure measurements in the tuyere have been carried out simultaneously. Pressure fluctuations at the injection point were monitored and correlated to the mode of bubble formation. The effects of high gas flow rates and high liquid viscosities have been examined in particular. Flow rates were employed up to 10-3 m3/s and viscosity to 0.5 Ns/m2. In order to attain a high gas momentum, the tuyere diameter was only 3 x 10-3 m. The experimental conditions and modeling liquids were chosen with special reference to the established practice of submerged gas injection to treat nonferrous slags. Such slags can be highly viscous. Bubble volume is smaller than that calculated from existing models such as those given by Davidson and Schüler10,11 due to the effect of gas momentum elongating the bubbles. On the other hand, viscosity tends to retard the bubble rise velocity, thus increasing volumes. To take elongation into account, a mathematical model is presented that assumes a prolate ellipsoidal shape of the bubbles. The unsteady potential flow equations for the liquid are solved for this case. Viscous effects are taken into account by noting that flow deviates from irrotational motion only in a thin boundary layer along the surface of the bubble. Thus, drag on the bubble can be obtained by calculating the viscous energy dissipation for potential flow past an ellipse. The time-dependent inertia coefficient for the ellipsoid is found by equating the vertical pressure increase inside and outside the bubble. This pressure change in the bubble is obtained by assuming that gas enters as a homogeneous jet and then calculating the stagnation pressure at the apex of

  3. Exercise-induced myofibrillar disruption with sarcolemmal integrity prior to simulated diving has no effect on vascular bubble formation in rats.

    PubMed

    Jørgensen, Arve; Foster, Philip P; Eftedal, Ingrid; Wisløff, Ulrik; Paulsen, Gøran; Havnes, Marianne B; Brubakk, Alf O

    2013-05-01

    Decompression sickness is initiated by gas bubbles formed during decompression, and it has been generally accepted that exercise before decompression causes increased bubble formation. There are indications that exercise-induced muscle injury seems to be involved. Trauma-induced skeletal muscle injury and vigorous exercise that could theoretically injure muscle tissues before decompression have each been shown to result in profuse bubble formation. Based on these findings, we hypothesized that exercise-induced skeletal muscle injury prior to decompression from diving would cause increase of vascular bubbles and lower survival rates after decompression. In this study, we examined muscle injury caused by eccentric exercise in rats prior to simulated diving and we observed the resulting bubble formation. Female Sprague-Dawley rats (n = 42) ran downhill (-16º) for 100 min on a treadmill followed by 90 min rest before a 50-min simulated saturation dive (709 kPa) in a pressure chamber. Muscle injury was evaluated by immunohistochemistry and qPCR, and vascular bubbles after diving were detected by ultrasonic imaging. The exercise protocol resulted in increased mRNA expression of markers of muscle injury; αB-crystallin, NF-κB, and TNF-α, and myofibrillar disruption with preserved sarcolemmal integrity. Despite evident myofibrillar disruption after eccentric exercise, no differences in bubble amounts or survival rates were observed in the exercised animals as compared to non-exercised animals after diving, a novel finding that may be applicable to humans.

  4. Galactic Teamwork Makes Distant Bubbles

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-03-01

    During the period of reionization that followed the dark ages of our universe, hydrogen was transformed from a neutral state, which is opaque to radiation, to an ionized one, which is transparent to radiation. But what generated the initial ionizing radiation? The recent discovery of multiple distant galaxies offers evidence for how this process occurred.Two Distant GalaxiesWe believe reionization occurred somewhere between a redshift of z = 6 and 7, because Ly-emitting galaxies drop out at roughly this redshift. Beyond this distance, were generally unable to see the light from these galaxies, because the universe is no longer transparent to their emission. This is not always the case, however: if a bubble of ionized gas exists around a distant galaxy, the radiation can escape, allowing us to see the galaxy.This is true of two recently-discovered Ly-emitting galaxies, confirmed to be at a redshift of z~7 and located near one another in a region known as the Bremer Deep Field. The fact that were able to see the radiation from these galaxies means that they are in an ionized HII region presumably one of the earlier regions to have become reionized in the universe.But on their own, neither of these galaxies is capable of generating an ionized bubble large enough for their light to escape. So what ionized the region around them, and what does this mean for our understanding of how reionization occurred in the universe?A Little Help From FriendsLocation in different filters of the objects in the Hubble Bremer Deep Field catalog. The z~7 selection region is outlined by the grey box. BDF-521 and BDF-3299 were the two originally discovered galaxies; the remaining red markers indicate the additional six galaxies discovered in the same region. [Castellano et al. 2016]A team of scientists led by Marco Castellano (Rome Observatory, INAF) investigated the possibility that there are other, faint galaxies near these two that have helped to ionize the region. Performing a survey

  5. Magma mixing enhanced by bubble segregation

    NASA Astrophysics Data System (ADS)

    Wiesmaier, S.; Morgavi, D.; Renggli, C. J.; Perugini, D.; De Campos, C. P.; Hess, K.-U.; Ertel-Ingrisch, W.; Lavallée, Y.; Dingwell, D. B.

    2015-08-01

    In order to explore the materials' complexity induced by bubbles rising through mixing magmas, bubble-advection experiments have been performed, employing natural silicate melts at magmatic temperatures. A cylinder of basaltic glass was placed below a cylinder of rhyolitic glass. Upon melting, bubbles formed from interstitial air. During the course of the experimental runs, those bubbles rose via buoyancy forces into the rhyolitic melt, thereby entraining tails of basaltic liquid. In the experimental run products, these plume-like filaments of advected basalt within rhyolite were clearly visible and were characterised by microCT and high-resolution EMP analyses. The entrained filaments of mafic material have been hybridised. Their post-experimental compositions range from the originally basaltic composition through andesitic to rhyolitic composition. Rheological modelling of the compositions of these hybridised filaments yield viscosities up to 2 orders of magnitude lower than that of the host rhyolitic liquid. Importantly, such lowered viscosities inside the filaments implies that rising bubbles can ascend more efficiently through pre-existing filaments that have been generated by earlier ascending bubbles. MicroCT imaging of the run products provides textural confirmation of the phenomenon of bubbles trailing one another through filaments. This phenomenon enhances the relevance of bubble advection in magma mixing scenarios, implying as it does so, an acceleration of bubble ascent due to the decreased viscous resistance facing bubbles inside filaments and yielding enhanced mass flux of mafic melt into felsic melt via entrainment. In magma mixing events involving melts of high volatile content, bubbles may be an essential catalyst for magma mixing. Moreover, the reduced viscosity contrast within filaments implies repeated replenishment of filaments with fresh end-member melt. As a result, complex compositional gradients and therefore diffusion systematics can be

  6. Prevalence, etiology, and types of dental trauma in children and adolescents: systematic review and meta-analysis

    PubMed Central

    Azami-Aghdash, Saber; Ebadifard Azar, Farbod; Pournaghi Azar, Fatemeh; Rezapour, Aziz; Moradi-Joo, Mohammad; Moosavi, Ahmad; Ghertasi Oskouei, Sina

    2015-01-01

    Background: Dental traumas are common among children and adolescents in many societies posing health and social problems. The aim of this study was to conduct a systematic review and meta-analysis on prevalence, etiology, types, and other epidemiologic aspects of dental trauma in children and adolescents (0-18 years old). Methods: In this systematic meta-analytical review, data were collected searching for key words including traumatic dental injuries, dental trauma, dental injury, dental trauma, tooth injuries, tooth trauma, traumatized teeth, dentoalveolar trauma, oral trauma, epidemiology, etiology, prevalence, incidence, occurrence, child*, and adolescence in the following databases: Scopus, CINAHL, Science Direct, PubMed and Google scholar. Results: From the total of 3197 articles, 44 completely relevant papers were included in the study. The prevalence of dental trauma was variable based on geographical area and was estimated 17.5% in the population, with higher prevalence in boys. Falling was the major cause for dental trauma, and the most frequent location was home. The most frequent type of trauma was enamel fracture. Conclusion: A relatively high prevalence was detected for dental trauma, which calls for effective planning and intervention to prevent the occurrence in children and adolescents. These may include special care for children, eliminating fall-prone areas, installing safety measures at homes, using protective appliances in sports, education, and raising the knowledge and availability of services to address enamel fracture. Region-specific criteria should be taken into account in programs and interventions. PMID:26793672

  7. Mechanism of single-bubble sonoluminescence

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    1999-08-01

    The mechanism of the light emission of single-bubble sonoluminescence (SBSL) is studied theoretically based on the quasiadiabatic compression model. It is concluded that SBSL is not the blackbody radiation but the thermal radiation. It is clarified that the shape of the spectrum is determined by the temperature inside the bubble and the intensity is determined by the rates of the microscopic processes of the light emission. For a noble-gas bubble, radiative recombination of electrons and ions and electron-atom bremsstrahlung are the dominant microscopic processes of the light emission, and the intensity is mainly determined by the degree of ionization of the gas inside the bubble. It is also clarified that for a noble-gas bubble the pulse width of the light is nearly independent of wavelength.

  8. Mechanism of single-bubble sonoluminescence.

    PubMed

    Yasui, K

    1999-08-01

    The mechanism of the light emission of single-bubble sonoluminescence (SBSL) is studied theoretically based on the quasiadiabatic compression model. It is concluded that SBSL is not the blackbody radiation but the thermal radiation. It is clarified that the shape of the spectrum is determined by the temperature inside the bubble and the intensity is determined by the rates of the microscopic processes of the light emission. For a noble-gas bubble, radiative recombination of electrons and ions and electron-atom bremsstrahlung are the dominant microscopic processes of the light emission, and the intensity is mainly determined by the degree of ionization of the gas inside the bubble. It is also clarified that for a noble-gas bubble the pulse width of the light is nearly independent of wavelength.

  9. A simple collision model for small bubbles

    NASA Astrophysics Data System (ADS)

    Heitkam, Sascha; Sommer, Anna-Elisabeth; Drenckhan, Wiebke; Fröhlich, Jochen

    2017-03-01

    In this work, a model for the interaction force between a small bubble and a wall or another bubble is presented. The formulation is especially designed for Lagrangian calculations of bubble or soft sphere trajectories, with or without resolution of the continuous fluid. The force only relies on position and velocity of the bubble. The model does not include any empirical parameter that would have to be calibrated. Therefore, this force model is easy to implement. The formulation of the force is explicit, which means low computational effort. The collision of a small bubble with an inclined top wall is investigated numerically and experimentally. The computational results achieved with the new collision model show good agreement with the experiment.

  10. Towards observable signatures of other bubble universes

    SciTech Connect

    Aguirre, Anthony; Johnson, Matthew C.; Shomer, Assaf

    2007-09-15

    We evaluate the possibility of observable effects arising from collisions between vacuum bubbles in a universe undergoing false-vacuum eternal inflation. Contrary to conventional wisdom, we find that under certain assumptions most positions inside a bubble should have access to a large number of collision events. We calculate the expected number and angular size distribution of such collisions on an observer's 'sky', finding that for typical observers the distribution is anisotropic and includes many bubbles, each of which will affect the majority of the observer's sky. After a qualitative discussion of the physics involved in collisions between arbitrary bubbles, we evaluate the implications of our results, and outline possible detectable effects. In an optimistic sense, then, the present paper constitutes a first step in an assessment of the possible effects of other bubble universes on the cosmic microwave background and other observables.

  11. Bubble chamber as a trace chemical detector.

    PubMed

    Luo, X; McCreary, E I; Atencio, J H; McCown, A W; Sander, R K

    1998-08-20

    A novel concept for trace chemical analysis in liquids has been demonstrated. The technique utilizes light absorption in a superheated liquid. Although a superheated liquid is thermodynamically unstable, a high degree of superheating can be dynamically achieved for a short period of time. During this time the superheated liquid is extremely sensitive to boiling at nucleation sites produced by energy deposition. Observation of bubbles in the superheated liquid in some sense provides amplification of the initial energy deposition. Bubble chambers containing superheated liquids have been used to detect energetic particles; now a bubble chamber is used to detect a trace chemical in superheated liquid propane by observing bubble formation initiated by optical absorption. Crystal violet is used as a test case and can be detected at the subpart-per-10(12) level by using a Nd:YAG laser. The mechanism for bubble formation and ideas for further improvement are discussed.

  12. Air bubble migration rates as a proxy for bubble pressure distribution in ice cores

    NASA Astrophysics Data System (ADS)

    Dadic, Ruzica; Schneebeli, Martin; Bertler, Nancy

    2015-04-01

    Air bubble migration can be used as a proxy to measure the pressure of individual bubbles and can help constrain the gradual close-off of gas bubbles and the resulting age distribution of gases in ice cores. The close-off depth of single bubbles can vary by tens of meters, which leads to a distribution of pressures for bubbles at a given depth. The age distribution of gases (along with gas-age-ice-age differences) decreases the resolution of the gas level reconstructions from ice cores and limits our ability to determine the phase relationship between gas and ice, and thus, the impact of rapid changes of greenhouse gases on surface temperatures. For times of rapid climate change, including the last 150 years, and abrupt climate changes further back in the past, knowledge of the age distribution of the gases trapped in air bubbles will enable us to refine estimates of atmospheric changes. When a temperature gradient is applied to gas bubbles in an ice sample, the bubbles migrate toward warmer ice. This motion is caused by sublimation from the warm wall and subsequent frost deposition on the cold wall. The migration rate depends on ice temperature and bubble pressure and is proportional to the temperature gradient. The spread in migration rates for bubbles in the same samples at given temperatures should therefore reflect the variations in bubble pressures within a sample. Air bubbles with higher pressures would have been closed off higher in the firn column and thus have had time to equilibrate with the surrounding ice pressure, while air bubbles that have been closed off recently would have pressures that are similar to todays atmospheric pressure above the firn column. For ice under pressures up to ~13-16 bar, the pressure distribution of bubbles from a single depth provides a record of the trapping function of air bubbles in the firn column for a certain time in the past. We will present laboratory experiments on air bubble migration, using Antarctic ice core

  13. Growth of a gas bubble in a supersaturated and slightly compressible liquid at low Mach number

    NASA Astrophysics Data System (ADS)

    Mohammadein, S. A.; Mohamed, K. G.

    2011-12-01

    In this paper, the growth of a gas bubble in a supersaturated and slightly compressible liquid is discussed. The mathematical model is solved analytically by using the modified Plesset and Zwick method. The growth process is affected by: sonic speed in the liquid, polytropic exponent, diffusion coefficient, initial concentration difference, surface tension, viscosity, adjustment factor and void fraction. The famous formula of Plesset and Zwick is produced as a special case of the result at some values of the adjustment factor. Moreover, the resultant formula is implemented to the case of the growth of underwater gas bubble.

  14. Mechanism of single-bubble sonoluminescence

    NASA Astrophysics Data System (ADS)

    An, Yu

    2006-08-01

    Considering almost all the effective processes of physics and chemical reaction in our numerical computation model, we investigate the mechanism of single bubble sonoluminescence (SBSL). For those sonoluminescing single bubbles in water at its flashing phase, the numerical simulation reveals that if the temperature inside the bubble is not high enough which may result in the plenty oxygen molecules and OH radicals undissociated, such as the case of a single argon bubble in 20°C or 34°C water, the radiative attachment of electrons to oxygen molecules and OH radicals contributes most to the SBSL; if the temperature inside the bubble is higher which makes most of the water vapor inside the bubble dissociate into oxygen and hydrogen atoms, such as the case of an argon bubble or a helium bubble in 0°C water, the radiative attachment of electrons to oxygen and hydrogen atoms dominates the SBSL; if the temperature is still higher, such as the case of a xenon bubble in 0°C water, the contribution from electron-neutral atom bremsstrahlung and electron-ion bremsstrahlung and recombination would be comparable with the contribution from the radiative attachment of electrons to oxygen and hydrogen atoms, and they together dominate the SBSL. For sonoluminescing single bubbles in those low vapor pressure liquids, such as in 85wt.% sulphuric acid, the electron-neutral atom bremsstrahlung and the electron-ion bremsstrahlung and recombination contribute most to the continuous spectrum part of SBSL. The present calculation also provides good interpretations to those observed phenomena, such as emitted photon numbers, the width of optical pulses, the blackbody radiation like spectra. The temperature fitted by the blackbody radiation formula is very different from that calculated by the gas dynamics equations. Besides, the effect of chemical dissociation on the shock wave is also discussed.

  15. Mechanism of single-bubble sonoluminescence.

    PubMed

    An, Yu

    2006-08-01

    Considering almost all the effective processes of physics and chemical reaction in our numerical computation model, we investigate the mechanism of single bubble sonoluminescence (SBSL). For those sonoluminescing single bubbles in water at its flashing phase, the numerical simulation reveals that if the temperature inside the bubble is not high enough which may result in the plenty oxygen molecules and OH radicals undissociated, such as the case of a single argon bubble in 20 degrees C or 34 degrees C water, the radiative attachment of electrons to oxygen molecules and OH radicals contributes most to the SBSL; if the temperature inside the bubble is higher which makes most of the water vapor inside the bubble dissociate into oxygen and hydrogen atoms, such as the case of an argon bubble or a helium bubble in 0 degrees C water, the radiative attachment of electrons to oxygen and hydrogen atoms dominates the SBSL; if the temperature is still higher, such as the case of a xenon bubble in 0 degrees C water, the contribution from electron-neutral atom bremsstrahlung and electron-ion bremsstrahlung and recombination would be comparable with the contribution from the radiative attachment of electrons to oxygen and hydrogen atoms, and they together dominate the SBSL. For sonoluminescing single bubbles in those low vapor pressure liquids, such as in 85 wt.% sulphuric acid, the electron-neutral atom bremsstrahlung and the electron-ion bremsstrahlung and recombination contribute most to the continuous spectrum part of SBSL. The present calculation also provides good interpretations to those observed phenomena, such as emitted photon numbers, the width of optical pulses, the blackbody radiation like spectra. The temperature fitted by the blackbody radiation formula is very different from that calculated by the gas dynamics equations. Besides, the effect of chemical dissociation on the shock wave is also discussed.

  16. Primary Particles from different bubble generation techniques

    NASA Astrophysics Data System (ADS)

    Butcher, A. C.; King, S. M.; Rosenoern, T.; Nilsson, E. D.; Bilde, M.

    2011-12-01

    Sea spray aerosols (SSA) are of major interest to global climate models due to large uncertainty in their emissions and ability to form Cloud Condensation Nuclei (CCN). In general, SSA are produced from wind breaking waves that entrain air and cause bubble bursting on the ocean surface. Preliminary results are presented for bubble generation, bubble size distribution, and CCN activity for laboratory generated SSA. In this study, the major processes of bubble formation are examined with respect to particle emissions. It has been suggested that a plunging jet closely resembles breaking wave bubble entrainment processes and subsequent bubble size distributions (Fuentes, Coe et al. 2010). Figure 1 shows the different particle size distributions obtained from the various bubble generation techniques. In general, frits produce a higher concentration of particles with a stronger bimodal particle size distribution than the various jet configurations used. The experiments consist of a stainless steel cylinder closed at both ends with fittings for aerosol sampling, flow connections for the recirculating jet, and air supply. Bubble generation included a recirculating jet with 16 mm or 4 mm nozzles, a stainless steel frit, or a ceramic frit. The chemical composition of the particles produced via bubble bursting processes has been probed using particle CCN activity. The CCN activity of sodium chloride, artificial sea salt purchased from Tropic Marin, and laboratory grade artificial sea salt (Kester, Duedall et al. 1967) has been compared. Considering the the limits of the shape factor as rough error bars for sodium chloride and bubbled sea salt, the CCN activity of artificial sea salt, Tropic Marin sea salt, and sodium chloride are not significantly different. This work has been supported by the Carlsberg Foundation.

  17. Secondary Trauma in Children and School Personnel

    ERIC Educational Resources Information Center

    Motta, Robert W.

    2012-01-01

    A review of childhood secondary trauma is presented. Secondary trauma involves the transfer and acquisition of negative affective and dysfunctional cognitive states due to prolonged and extended contact with others, such as family members, who have been traumatized. As such, secondary trauma refers to a spread of trauma reactions from the victim…

  18. Self-Harm and Trauma

    MedlinePlus

    ... Z) Hepatitis HIV Mental Health Mental Health Home Suicide Prevention Substance Abuse Military Sexual Trauma PTSD Research ( ... you are outside your body or yourself Reduce stress and tension Block upsetting memories and flashbacks Show ...

  19. Effect of surfactants on single bubble sonoluminescence behavior and bubble surface stability.

    PubMed

    Leong, Thomas; Yasui, Kyuichi; Kato, Kazumi; Harvie, Dalton; Ashokkumar, Muthupandian; Kentish, Sandra

    2014-04-01

    The effect of surfactants on the radial dynamics of a single sonoluminescing bubble has been investigated. Experimentally, it is observed that an increase in the surfactant concentration leads to a decline in the oscillation amplitude and hence light emission intensity. Numerical simulations support this result, showing that under the driving pressures required to achieve single bubble sonoluminescence (SBSL), the surface properties, namely, the surface elasticity and dilatational viscosity, contribute to the damping of the radial amplitude in the bubble oscillation. In most cases this stabilizes the bubble surface, and contributes to a decreased light intensity. A stronger driving pressure is necessary to achieve equivalent light emission to a surfactant-free bubble. However, as the driving pressure is increased, the surface stability also decreases, making it practically very difficult for a bubble to achieve high SBSL intensities in concentrated surfactant solutions. Although more stable owing to more mild pulsations, the instability mechanism for a surfactant-coated bubble at higher ambient radii is more likely to be of the Rayleigh-Taylor type than that of a clean bubble at the same given acoustic parameters, which can lead to bubble disintegration before correcting mechanisms can bring the bubble back into the stable sonoluminescence regime.

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

    PubMed

    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.

  1. Mental Findings in Trauma Victims

    PubMed Central

    CAN, İsmail Özgür; DEMİROĞLU UYANIKER, Zehra; ULAŞ, Halis; KARABAĞ, Gökmen; CİMİLLİ, Can; SALAÇİN, Serpil

    2013-01-01

    Introduction In medico-legal evaluation of trauma patients, the bio-psychological effects of the trauma and the severity of the injuries require to be evaluated. In this study, assuming the fact that psychiatric assessment is not taken into consideration in physical trauma cases, we planned to show the presence of psychological trauma in our medico-legally evaluated patients who presented with different types of traumas and to review the mental findings and diagnoses in trauma victims. Method We retrospectively analyzed the hospital records of 1975 patients aged 18 years or older who presented to the Department of Forensic Medicine at Dokuz Eylül University School of Medicine for medico-legal evaluation between 1999 and 2009. Psychiatric assessment was performed in 142 patients by the Department of Psychiatry. The data contained in medico-legal reports and patient records were then examined with respect to patients’ age, gender, nature of traumatic events, psychiatric diagnoses, descriptive characteristics of the patients, severity of trauma and past history of mental disorder and trauma experience. Results of the medicolegal evaluations were also analyzed. Result Of the 142 patients, 80 (56.3%) were female and their average age was 40.30±17.17 years. The most frequent traumatic events were traffic accidents (29.6%) and violence-related blunt force trauma (28.9%). When the distribution of the most common psychiatric diagnoses was examined, it was found that anxiety disorders were found in 69 cases (48.6%), adjustment disorders were found in 16 cases (11.3%) and mood disorders were found in 12 cases (8.5%). Among anxiety disorders, acute stress disorder (n=39) and post-traumatic stress disorder (PTSD) (n=27) were the most common ones. In 27 cases of the 142, it was determined that, psychiatric symptoms and findings did not meet the diagnostic criteria of any psychiatric disorder. Diagnosis of psychiatric disorder was not significantly related with traumatic

  2. Influence of bubble size, diffuser width, and flow rate on the integral behavior of bubble plumes

    NASA Astrophysics Data System (ADS)

    Fraga, Bruño.; Stoesser, Thorsten

    2016-06-01

    A large-eddy simulation based Eulerian-Lagrangian model is employed to quantify the impact of bubble size, diffuser diameter, and gas flow rate on integral properties of bubble plumes, such as the plume's width, centerline velocity, and mass flux. Calculated quantities are compared with experimental data and integral model predictions. Furthermore, the LES data were used to assess the behavior of the entrainment coefficient, the momentum amplification factor, and the bubble-to-momentum spread ratio. It is found that bubble plumes with constant bubble size and smaller diameter behave in accordance with integral plume models. Plumes comprising larger and non-uniform bubble sizes appear to deviate from past observations and model predictions. In multi-diameter bubble plumes, a bubble self-organisation takes place, i.e., small bubbles cluster in the center of the plume whilst large bubbles are found at the periphery of the plume. Multi-diameter bubble plumes also feature a greater entrainment rate than single-size bubble plumes, as well as a higher spread ratio and lower turbulent momentum rate. Once the plume is fully established, the size of the diffuser does not appear to affect integral properties of bubble plumes. However, plume development is affected by the diffuser width, as larger release areas lead to a delayed asymptotic behavior of the plume and consequently to a lower entrainment and higher spread ratio. Finally, the effect of the gas flow rate on the integral plume is studied and is deemed very relevant with regards to most integral plume properties and coefficients. This effect is already fairly well described by integral plume models.

  3. Special Days, Special Ways.

    ERIC Educational Resources Information Center

    Clarke, Jacqueline

    2001-01-01

    Presents unique ways to create special rituals that recognize individual students' achievements and milestones. Ideas include throwing a send-off party for a student who is moving; holding monthly birthday luncheons; choosing an ambassador to accompany new students around school; and making a lost tooth container that students can use to safely…

  4. Microwave emission of sonoluminescing bubbles.

    PubMed

    Hammer, Dominik; Frommhold, Lothar

    2002-07-01

    Kordomenos et al. have attempted to measure single bubble sonoluminescence (SBSL) emission in the microwave window of water in a band of frequencies ranging from 1.65 GHz to 2.35 GHz [Phys. Rev. E 59, 1781 (1999)]. The sensitivity of the experiment was such that signals greater than 1 nW would have been detected. We show here that this upper bound is compatible with the radiation processes that we think generate significant emission at optical frequencies, electron-neutral and electron-ion bremsstrahlung. In fact, we argue that, almost independently of the specific assumptions concerning the hydrodynamics or the nature of the radiative processes, SBSL intensities exceeding that upper bound can hardly be expected.

  5. Nasal septal trauma in children.

    PubMed

    Olsen, K D; Carpenter, R J; Kern, E B

    1979-07-01

    If the septal component of a nasal injury is adequately managed, usually the entire nasal injury will be well managed. Major or minor nasal trauma can cause cartilage fracture, deviation, dislocation, hematoma, or abscess formation, and the various associated sequelae, some of them life-threatening. A negative x-ray report should never be used as a substitute for a complete intranasal examination in any child with nasal trauma. Any nasal abnormality should be referred for immediate evaluation and treatment.

  6. Inert gas bubbles in bcc Fe

    NASA Astrophysics Data System (ADS)

    Gai, Xiao; Smith, Roger; Kenny, S. D.

    2016-03-01

    The properties of inert gas bubbles in bcc Fe is examined using a combination of static energy minimisation, molecular dynamics and barrier searching methods with empirical potentials. Static energy minimisation techniques indicate that for small Ar and Xe bubbles, the preferred gas to vacancy ratio at 0 K is about 1:1 for Ar and varies between 0.5:1 and 0.9:1 for Xe. In contrast to interstitial He atoms and small He interstitial clusters, which are highly mobile in the lattice, Ar and Xe atoms prefer to occupy substitutional sites and any interstitials present in the lattice soon displace Fe atoms and become substitutional. If a pre-existing bubble is present then there is a capture radius around a bubble which extends up to the 6th neighbour position. Collision cascades can also enlarge an existing bubble by the capture of vacancies. Ar and Xe can diffuse through the lattice through vacancy driven mechanisms but with relatively high energy barriers of 1.8 and 2.0 eV respectively. This indicates that Ar and Xe bubbles are much harder to form than bubbles of He and that such gases produced in a nuclear reaction would more likely be dispersed at substitutional sites without the help of increased temperature or radiation-driven mechanisms.

  7. Surfactants for Bubble Removal against Buoyancy.

    PubMed

    Raza, Md Qaisar; Kumar, Nirbhay; Raj, Rishi

    2016-01-08

    The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications.

  8. Bubbles in live-stranded dolphins

    PubMed Central

    Dennison, S.; Moore, M. J.; Fahlman, A.; Moore, K.; Sharp, S.; Harry, C. T.; Hoppe, J.; Niemeyer, M.; Lentell, B.; Wells, R. S.

    2012-01-01

    Bubbles in supersaturated tissues and blood occur in beaked whales stranded near sonar exercises, and post-mortem in dolphins bycaught at depth and then hauled to the surface. To evaluate live dolphins for bubbles, liver, kidneys, eyes and blubber–muscle interface of live-stranded and capture-release dolphins were scanned with B-mode ultrasound. Gas was identified in kidneys of 21 of 22 live-stranded dolphins and in the hepatic portal vasculature of 2 of 22. Nine then died or were euthanized and bubble presence corroborated by computer tomography and necropsy, 13 were released of which all but two did not re-strand. Bubbles were not detected in 20 live wild dolphins examined during health assessments in shallow water. Off-gassing of supersaturated blood and tissues was the most probable origin for the gas bubbles. In contrast to marine mammals repeatedly diving in the wild, stranded animals are unable to recompress by diving, and thus may retain bubbles. Since the majority of beached dolphins released did not re-strand it also suggests that minor bubble formation is tolerated and will not lead to clinically significant decompression sickness. PMID:21993505

  9. Surfactants for Bubble Removal against Buoyancy

    PubMed Central

    Raza, Md. Qaisar; Kumar, Nirbhay; Raj, Rishi

    2016-01-01

    The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications. PMID:26743179

  10. Bubble Growth and Detachment from a Needle

    NASA Astrophysics Data System (ADS)

    Shusser, Michael; Rambod, Edmond; Gharib, Morteza

    1999-11-01

    The release of bubbles from an underwater nozzle or orifice occurs in large number of applications, such as perforated plate columns, blood oxygenators and various methods of water treatment. It is also a widely used method in laboratory research on multiphase flow and acoustics for generating small bubbles in a controlled fashion. We studied experimentally the growth and pinch-off of air bubbles released from a submerged needle into a quiescent liquid or a liquid flowing parallel to the needle. Micron-sized bubbles were generated by an air-liquid dispenser. High-speed imaging was performed to study the formation and detachment of bubbles from the tip of the needle. The impact of the needle diameter was investigated and the size and number of produced bubbles were assessed for different flow rates of air and for different velocities of the imposed upward liquid flow. The results were compared with available theoretical models and numerical computations. The existence of a critical gas flow rate and two regimes of bubble growth were verified.

  11. Bubbles in live-stranded dolphins.

    PubMed

    Dennison, S; Moore, M J; Fahlman, A; Moore, K; Sharp, S; Harry, C T; Hoppe, J; Niemeyer, M; Lentell, B; Wells, R S

    2012-04-07

    Bubbles in supersaturated tissues and blood occur in beaked whales stranded near sonar exercises, and post-mortem in dolphins bycaught at depth and then hauled to the surface. To evaluate live dolphins for bubbles, liver, kidneys, eyes and blubber-muscle interface of live-stranded and capture-release dolphins were scanned with B-mode ultrasound. Gas was identified in kidneys of 21 of 22 live-stranded dolphins and in the hepatic portal vasculature of 2 of 22. Nine then died or were euthanized and bubble presence corroborated by computer tomography and necropsy, 13 were released of which all but two did not re-strand. Bubbles were not detected in 20 live wild dolphins examined during health assessments in shallow water. Off-gassing of supersaturated blood and tissues was the most probable origin for the gas bubbles. In contrast to marine mammals repeatedly diving in the wild, stranded animals are unable to recompress by diving, and thus may retain bubbles. Since the majority of beached dolphins released did not re-strand it also suggests that minor bubble formation is tolerated and will not lead to clinically significant decompression sickness.

  12. Bubbly Suspension Generated in Low Gravity

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.

    2000-01-01

    Bubbly suspensions are crucial for mass and heat transport processes on Earth and in space. These processes are relevant to pharmaceutical, chemical, nuclear, and petroleum industries on Earth. They are also relevant to life support, in situ resource utilization, and propulsion processes for long-duration space missions such as the Human Exploration and Development of Space program. Understanding the behavior of the suspension in low gravity is crucial because of factors such as bubble segregation, which could result in coalescence and affect heat and mass transport. Professors A. Sangani and D. Koch, principal investigators in the Microgravity Fluid Physics Program managed by the NASA Glenn Research Center at Lewis Field, are studying the physics of bubbly suspension. They plan to shear a bubbly suspension in a couette cell in microgravity to study bubble segregation and compare the bubble distribution in the couette gap with the one predicted by the suspension-averaged equations of motion. Prior to the Requirement Definition Review of this flight experiment, a technology for generating a bubbly suspension in microgravity has to be established, tested, and verified.

  13. Surfactants for Bubble Removal against Buoyancy

    NASA Astrophysics Data System (ADS)

    Raza, Md. Qaisar; Kumar, Nirbhay; Raj, Rishi

    2016-01-01

    The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications.

  14. Acoustic Bubble Removal from Boiling Surfaces

    NASA Technical Reports Server (NTRS)

    Prosperetti, Andrea

    2002-01-01

    The object of the study was the investigation of the forces generated by standing acoustic waves on vapor bubbles, both far and near boundaries. In order to accomplish this objective, in view of the scarcity of publications on the topic, it has been necessary to build an edifice of knowledge about vapor bubbles in sound and flow fields from the ground up, as it were. We have addressed problems of gradually greater difficulty as follows: 1. In the first place, the physics of an stationary isolated bubble subject to a sound field in an unbounded liquid was addressed; 2. The case of bubbles translating in a stationary pressure field was then considered; 3. This was followed by a study of the combined effects of sound and translation, 4. And of a neighboring boundary 5. Finally, a new method to deal with nonspherical bubbles was developed- In addition to the work on vapor bubbles, some studies on gas bubbles were conducted in view of NASA's interest in the phenomenon of sonoluminescence.

  15. Understanding Peat Bubbles: Biogeochemical-Hydrological Linkages

    NASA Astrophysics Data System (ADS)

    Strack, M.

    2009-05-01

    Decomposition of organic matter in peatland ecosystems produces gaseous end-products that can accumulate at depth and result in the build up of free-phase gas below the water table. This free-phase gas, or bubbles, reduces hydraulic conductivity, alters hydrologic and chemical gradients, and affects productivity surface vegetation through its role in peat buoyancy. In terms of greenhouse gas dynamics, these bubbles are likely the dominant subsurface stock of methane (CH4) and release of this CH4 to the atmosphere via ebullition may account for a significant portion of total efflux. Despite the importance of entrapped bubbles for peatland ecohydrological function there is still little known about how the quantity of bubbles varies between peatland types and at smaller scales within a peatland. Profiles of bubbles collected from several locations within four peatlands reveal that bubble volume varies significant among peatlands, between microforms and with depth. Previous studies also suggest that ebullition is spatially and temporally variable. This spatial variability may have important impacts on system ecohydrology and should be incorporated in models of peatland hydrology and development. This requires the difficult task of mapping bubble volume in three dimensions and over large areas. The potential for geophysical methods and the use of surface features to address this task will be discussed.

  16. The Age of the Local Interstellar Bubble

    NASA Astrophysics Data System (ADS)

    Abt, H. A.

    2011-12-01

    The Local Interstellar Bubble is an irregular-shaped region that happens to be centered on the Sun. It has minimum and maximum radii of 50 and 150 pc. The density inside the bubble is 1/200 of that outside and the temperature is about 1 million K. Therefore the density times the temperature at the borders is constant, so the bubble is stable and can be very old. It was evidently cleared of interstellar gas by one or more supernovae. Because of the low density, no new stars could have been formed in the bubble since the supernovae explosions. We looked for the youngest stars within the bubble. In the central region they are B7 so that region is about 160 million years old. The Pleiades lobe has B3 stars so it is about 60 million years old. The lobe toward the galactic center has O9.5 stars so it is about 4 million years old. In fact, it has a pulsar with a spin-down time of 3.76 million years, so that must be the remnant of the supernova that created that region. The bubble has measureable OVI and CII lines, but no HI, confirming its high temperature. The Sun was probably formed elsewhere and happened to drift into the bubble some millions of years ago. The full text of this talk was published in the Astronomical Journal (Abt 2011).

  17. Mean bubble formation time in DNA denaturation

    NASA Astrophysics Data System (ADS)

    Murthy, K. P. N.; Schütz, G. M.

    2011-12-01

    Using the Poland-Scheraga free energy of the bubble size in a double-stranded DNA we propose a discrete stochastic dynamics for the number of base pairs N of an unzipped bubble. We derive a universal subdiffusive growth TN~A/Γ(b+2)N1+b for the mean formation time (MBFT) TN of a bubble of size N. The amplitude A is determined by the bubble initiation rate and time spent in the denaturated state. We examine critically the significance of these results for experiments. We find: i) Our results provide a new method to determine whether the order of the denaturation transition is discontinuous (b>2) or not. ii) The asymptotic growth law of TN is reached with 10% precision already for small bubbles of sizes >20. However, the amplitude is very sensitive to modeling details for small bubbles. iii) In an equilibrium sample of bubbles up to size N the averaged MBFT grows diffusively, TN*~N2, irrespective of b.

  18. Renal Trauma: The Rugby Factor

    PubMed Central

    Freeman, Catherine M.; Kelly, Michael E.; Nason, Gregory J.; McGuire, Barry B.; Kilcoyne, Aoife; Ryan, John; Lennon, Gerald; Galvin, David; Quinlan, David; Mulvin, David

    2015-01-01

    Introduction Renal trauma accounts for 5% of all trauma cases. Rare mechanisms of injuries including sports participation are increasingly common. Rugby-related trauma poses a conundrum for physicians and players due to the absence of clear guidelines and a paucity of evidence. Our series highlights traumatic rugby-related renal injuries in our institution, and emphasize the need for international guidelines on management. Methods A retrospective review of all abdominal traumas between January 2006 and April 2013, specifically assessing for renal related trauma that were secondary to rugby injuries was performed. All patients' demographics, computerized tomography results, hematological and biochemical results and subsequent management were recorded. Results Five male patients presented with rugby-related injuries. Mean age was 21 years old. All patients were hemodynamically stable and managed conservatively in acute setting. One patient was detected to have an unknown pre-existing atrophic kidney that had been subsequently injured, and was booked for an elective nephrectomy an 8-week interval. Conclusion Rugby-related trauma has generated essential attention. This paper serves to highlight this type of injury and the need for defined guidelines on role of imaging and international consensus on timing of return to contact sport, in both professional and amateur settings. PMID:26889132

  19. Luminescence flash and temperature determination of the bubble generated by underwater pulsed discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Liancheng; Zhu, Xinlei; Yan, Hui; Huang, Yifan; Liu, Zhen; Yan, Keping

    2017-01-01

    An intense luminescence flash can be induced during the collapse phase of bubbles generated by pulsed discharge in water. To gain insight into this special phenomenon, we experimentally investigated the optical characteristics and luminescence temperature inside collapsing bubbles. The duration of the luminescence flash generated by pulsed discharge was around tens of microseconds, which was confirmed by high-speed recording and the photodiode output, and the inception time of the luminescence flash was approximately 32.5 μs before the bubble collapsed to its minimum size. The temperatures of the luminescence flash at discharge energies of 25 and 30 J/pulse calculated according to the two-line radiance ratio method were 6673 and 6728 K, respectively.

  20. Trauma and termination.

    PubMed

    Ferraro, F

    1995-02-01

    The author suggests a particular reading of the thesis put forward by Freud in 'Analysis terminable and interminable' that an effective and more definitive conclusion may be expected in analyses of cases with traumatic aetiology. This reading shifts the emphasis from the patient's history to the possibility of its crystallising in focal nuclei emerging within the analytic relationship under the pressure of the termination. The revival of separation anxieties which cannot be worked through, and their crystallisation in precipitating traumatic events, may give rise to decisive psychic work allowing the analysis to be brought to a conclusion. Two case histories are presented to show how the end of the analysis assumes the form of a new trauma, which reactivates in the present, traumatic anxieties from the patient's own infantile history. In the first case a premature birth and in the second a miscarriage, originally experienced as isolated automatic events without time or history, are relived in the terminal phase as vicissitudes of the transference, so that new meaning can be assigned to them and they can be withdrawn from the somatic cycle of repetition. The powerful tendency to act out and the intense countertransference pressure on the analyst are discussed in the light of the specificities of this phase, which is crucial to the success of the analysis. This leads to a re-examination, in the concluding notes, of some theoretical questions inherent in the problem of the termination and, in particular, to a discussion of the ambiguous concept of a natural ending.

  1. Trauma of the midface

    PubMed Central

    Kühnel, Thomas S.; Reichert, Torsten E.

    2015-01-01

    Fractures of the midface pose a serious medical problem as for their complexity, frequency and their socio-economic impact. Interdisciplinary approaches and up-to-date diagnostic and surgical techniques provide favorable results in the majority of cases though. Traffic accidents are the leading cause and male adults in their thirties are affected most often. Treatment algorithms for nasal bone fractures, maxillary and zygomatic fractures are widely agreed upon whereas trauma to the frontal sinus and the orbital apex are matter of current debate. Advances in endoscopic surgery and limitations of evidence based gain of knowledge are matters that are focused on in the corresponding chapter. As for the fractures of the frontal sinus a strong tendency towards minimized approaches can be seen. Obliteration and cranialization seem to decrease in numbers. Some critical remarks in terms of high dose methylprednisolone therapy for traumatic optic nerve injury seem to be appropriate. Intraoperative cone beam radiographs and preshaped titanium mesh implants for orbital reconstruction are new techniques and essential aspects in midface traumatology. Fractures of the anterior skull base with cerebrospinal fluid leaks show very promising results in endonasal endoscopic repair. PMID:26770280

  2. Radio Bubbles in Clusters of Galaxies

    SciTech Connect

    Dunn, Robert J.H.; Fabian, A.C.; Taylor, G.B.; /NRAO, Socorro /KIPAC, Menlo Park

    2005-12-14

    We extend our earlier work on cluster cores with distinct radio bubbles, adding more active bubbles, i.e. those with GHz radio emission, to our sample, and also investigating ''ghost bubbles'', i.e. those without GHz radio emission. We have determined k, which is the ratio of the total particle energy to that of the electrons radiating between 10MHz and 10GHz. Constraints on the ages of the active bubbles confirm that the ratio of the energy factor, k, to the volume filling factor, f lies within the range 1 {approx}< k/f {approx}< 1000. In the assumption that there is pressure equilibrium between the radio-emitting plasma and the surrounding thermal X-ray gas, none of the radio lobes has equipartition between the relativistic particles and the magnetic field. A Monte-Carlo simulation of the data led to the conclusion that there are not enough bubbles present in the current sample to be able to determine the shape of the population. An analysis of the ghost bubbles in our sample showed that on the whole they have higher upper limits on k/f than the active bubbles, especially when compared to those in the same cluster. A study of the Brightest 55 cluster sample shows that 17, possibly 20, clusters required some form of heating as they have a short central cooling time, t{sub cool} {approx}< 3 Gyr, and a large central temperature drop, T{sub centre}/T{sub outer} < 1/2. Of these between 12 (70 per cent) and 15 (75 per cent), contain bubbles. This indicates that the duty cycle of bubbles is large in such clusters and that they can play a major role in the heating process.

  3. Dynamics of two-dimensional bubbles.

    PubMed

    Piedra, Saúl; Ramos, Eduardo; Herrera, J Ramón

    2015-06-01

    The dynamics of two-dimensional bubbles ascending under the influence of buoyant forces is numerically studied with a one-fluid model coupled with the front-tracking technique. The bubble dynamics are described by recording the position, shape, and orientation of the bubbles as functions of time. The qualitative properties of the bubbles and their terminal velocities are described in terms of the Eötvos (ratio of buoyancy to surface tension) and Archimedes numbers (ratio of buoyancy to viscous forces). The terminal Reynolds number result from the balance of buoyancy and drag forces and, consequently, is not an externally fixed parameter. In the cases that yield small Reynolds numbers, the bubbles follow straight paths and the wake is steady. A more interesting behavior is found at high Reynolds numbers where the bubbles follow an approximately periodic zigzag trajectory and an unstable wake with properties similar to the Von Karman vortex street is formed. The dynamical features of the motion of single bubbles are compared to experimental observations of air bubbles ascending in a water-filled Hele-Shaw cell. Although the comparison is not strictly valid in the sense that the effect of the lateral walls is not incorporated in the model, most of the dynamical properties observed are in good qualitative agreement with the numerical calculations. Hele-Shaw cells with different gaps have been used to determine the degree of approximation of the numerical calculation. It is found that for the relation between the terminal Reynolds number and the Archimedes number, the numerical calculations are closer to the observations of bubble dynamics in Hele-Shaw cells of larger gaps.

  4. Pressure waves in a supersaturated bubbly magma

    USGS Publications Warehouse

    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.

  5. Nonlinear Bubble Interactions in Acoustic Pressure Fields

    NASA Technical Reports Server (NTRS)

    Barbat, Tiberiu; Ashgriz, Nasser; Liu, Ching-Shi

    1996-01-01

    The systems consisting of a two-phase mixture, as clouds of bubbles or drops, have shown many common features in their responses to different external force fields. One of particular interest is the effect of an unsteady pressure field applied to these systems, case in which the coupling of the vibrations induced in two neighboring components (two drops or two bubbles) may result in an interaction force between them. This behavior was explained by Bjerknes by postulating that every body that is moving in an accelerating fluid is subjected to a 'kinetic buoyancy' equal with the product of the acceleration of the fluid multiplied by the mass of the fluid displaced by the body. The external sound wave applied to a system of drops/bubbles triggers secondary sound waves from each component of the system. These secondary pressure fields integrated over the surface of the neighboring drop/bubble may result in a force additional to the effect of the primary sound wave on each component of the system. In certain conditions, the magnitude of these secondary forces may result in significant changes in the dynamics of each component, thus in the behavior of the entire system. In a system containing bubbles, the sound wave radiated by one bubble at the location of a neighboring one is dominated by the volume oscillation mode and its effects can be important for a large range of frequencies. The interaction forces in a system consisting of drops are much smaller than those consisting of bubbles. Therefore, as a first step towards the understanding of the drop-drop interaction subject to external pressure fluctuations, it is more convenient to study the bubble interactions. This paper presents experimental results and theoretical predictions concerning the interaction and the motion of two levitated air bubbles in water in the presence of an acoustic field at high frequencies (22-23 KHz).

  6. The Minnaert bubble: an acoustic approach

    NASA Astrophysics Data System (ADS)

    Devaud, Martin; Hocquet, Thierry; Bacri, Jean-Claude; Leroy, Valentin

    2008-11-01

    We propose an ab initio introduction to the well-known Minnaert pulsating bubble at graduate level. After a brief recall of the standard stuff, we begin with a detailed discussion of the radial movements of an air bubble in water. This discussion is managed from an acoustic point of view, and using the Lagrangian rather than the Eulerian variables. In unbounded water, the air-water system has a continuum of eigenmodes, some of them correspond to regular Fabry-Pérot resonances. A singular resonance, the lowest one, is shown to coincide with that of Minnaert. In bounded water, the eigenmodes spectrum is discrete, with a finite fundamental frequency. A spectacular quasi-locking of the latter occurs if it happens to exceed the Minnaert frequency, which provides an unforeseen one-bubble alternative version of the famous 'hot chocolate effect'. In the (low) frequency domain in which sound propagation inside the bubble reduces to a simple 'breathing' (i.e. inflation/deflation), the light air bubble can be 'dressed' by the outer water pressure forces, and is turned into the heavy Minnaert bubble. Thanks to this unexpected renormalization process, we demonstrate that the Minnaert bubble definitely behaves like a true harmonic oscillator of the spring-bob type, but with a damping term and a forcing term in apparent disagreement with those commonly admitted in the literature. Finally, we underline the double role played by the water. In order to tell the water motion associated with water compressibility (i.e. the sound) from the simple incompressible accompaniment of the bubble breathing, we introduce a new picture analogous to the electromagnetic radiative picture in Coulomb gauge, which naturally leads us to split the water displacement in an instantaneous and a retarded part. The Minnaert renormalized mass of the dressed bubble is then automatically recovered.

  7. Dynamics of two-dimensional bubbles

    NASA Astrophysics Data System (ADS)

    Piedra, Saúl; Ramos, Eduardo; Herrera, J. Ramón

    2015-06-01

    The dynamics of two-dimensional bubbles ascending under the influence of buoyant forces is numerically studied with a one-fluid model coupled with the front-tracking technique. The bubble dynamics are described by recording the position, shape, and orientation of the bubbles as functions of time. The qualitative properties of the bubbles and their terminal velocities are described in terms of the Eötvos (ratio of buoyancy to surface tension) and Archimedes numbers (ratio of buoyancy to viscous forces). The terminal Reynolds number result from the balance of buoyancy and drag forces and, consequently, is not an externally fixed parameter. In the cases that yield small Reynolds numbers, the bubbles follow straight paths and the wake is steady. A more interesting behavior is found at high Reynolds numbers where the bubbles follow an approximately periodic zigzag trajectory and an unstable wake with properties similar to the Von Karman vortex street is formed. The dynamical features of the motion of single bubbles are compared to experimental observations of air bubbles ascending in a water-filled Hele-Shaw cell. Although the comparison is not strictly valid in the sense that the effect of the lateral walls is not incorporated in the model, most of the dynamical properties observed are in good qualitative agreement with the numerical calculations. Hele-Shaw cells with different gaps have been used to determine the degree of approximation of the numerical calculation. It is found that for the relation between the terminal Reynolds number and the Archimedes number, the numerical calculations are closer to the observations of bubble dynamics in Hele-Shaw cells of larger gaps.

  8. MAGNETIC TOPOLOGY OF BUBBLES IN QUIESCENT PROMINENCES

    SciTech Connect

    Dudik, J.; Aulanier, G.; Schmieder, B.; Zapior, M.; Heinzel, P.

    2012-12-10

    We study a polar-crown prominence with a bubble and its plume observed in several coronal filters by the SDO/AIA and in H{alpha} by the MSDP spectrograph in Bialkow (Poland) to address the following questions: what is the brightness of prominence bubbles in EUV with respect to the corona outside of the prominence and the prominence coronal cavity? What is the geometry and topology of the magnetic field in the bubble? What is the nature of the vertical threads seen within prominences? We find that the brightness of the bubble and plume is lower than the brightness of the corona outside of the prominence, and is similar to that of the coronal cavity. We constructed linear force-free models of prominences with bubbles, where the flux rope is perturbed by inclusion of parasitic bipoles. The arcade field lines of the bipole create the bubble, which is thus devoid of magnetic dips. Shearing the bipole or adding a second one can lead to cusp-shaped prominences with bubbles similar to the observed ones. The bubbles have complex magnetic topology, with a pair of coronal magnetic null points linked by a separator outlining the boundary between the bubble and the prominence body. We conjecture that plume formation involves magnetic reconnection at the separator. Depending on the viewing angle, the prominence can appear either anvil-shaped with predominantly horizontal structures, or cusp-shaped with predominantly vertical structuring. The latter is an artifact of the alignment of magnetic dips with respect to the prominence axis and the line of sight.

  9. Single Bubble Sonoluminescence in Low Gravity and Optical Radiation Pressure Positioning of the Bubble

    NASA Technical Reports Server (NTRS)

    Thiessen, D. B.; Young, J. E.; Marr-Lyon, M. J.; Richardson, S. L.; Breckon, C. D.; Douthit, S. G.; Jian, P. S.; Torruellas, W. E.; Marston, P. L.

    1999-01-01

    Several groups of researchers have demonstrated that high frequency sound in water may be used to cause the regular repeated compression and luminescence of a small bubble of gas in a flask. The phenomenon is known as single bubble sonoluminescence (SBSL). It is potentially important because light emitted by the bubble appears to be associated with a significant concentration of energy within the volume of the bubble. Unfortunately, the detailed physical mechanisms causing the radiation of light by oscillating bubbles are poorly understood and there is some evidence that carrying out experiments in a weightless environment may provide helpful clues. In addition, the radiation pressure of laser beams on the bubble may provide a way of simulating weightless experiments in the laboratory. The standard model of SBSL attributes the light emission to heating within the bubble by a spherically imploding shock wave to achieve temperatures of 50,000 K or greater. In an alternative model, the emission is attributed to the impact of a jet of water which is required to span the bubble and the formation of the jet is linked to the buoyancy of the bubble. The coupling between buoyancy and jet formation is a consequence of the displacement of the bubble from a velocity node (pressure antinode) of the standing acoustic wave that drives the radial bubble oscillations. One objective of this grant is to understand SBSL emission in reduced buoyancy on KC-135 parabolic flights. To optimize the design of those experiments and for other reasons which will help resolve the role of buoyancy, laboratory experiments are planned in simulated low gravity in which the radiation pressure of laser light will be used to position the bubble at the acoustic velocity node of the ultrasonic standing wave. Laser light will also be used to push the bubble away from the velocity node, increasing the effective buoyancy. The original experiments on the optical levitation and radiation pressure on bubbles

  10. Three-dimensional magnetic bubble memory system

    NASA Technical Reports Server (NTRS)

    Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor)

    1994-01-01

    A compact memory uses magnetic bubble technology for providing data storage. A three-dimensional arrangement, in the form of stacks of magnetic bubble layers, is used to achieve high volumetric storage density. Output tracks are used within each layer to allow data to be accessed uniquely and unambiguously. Storage can be achieved using either current access or field access magnetic bubble technology. Optical sensing via the Faraday effect is used to detect data. Optical sensing facilitates the accessing of data from within the three-dimensional package and lends itself to parallel operation for supporting high data rates and vector and parallel processing.

  11. Mechanism of single-bubble sonoluminescence

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    2000-07-01

    The mechanism of the light emission of single-bubble sonoluminescence (SBSL) is studied theoretically for an argon bubble based on a quasi-adiabatic compression model. It is clarified that radiative recombination of electrons and ions and electron-atom bremsstrahlung are the dominant microscopic processes of the light emission and the intensity is mainly determined by the degree of ionization of the gas inside the bubble. It is also clarified that the pulse width of the light is nearly independent on wavelength.

  12. Satellites in the inviscid breakup of bubbles.

    PubMed

    Gordillo, J M; Fontelos, M A

    2007-04-06

    In this Letter, we stress the essential role played by gas inertia in the breakup of gas bubbles. Our results reveal that, whenever the gas to liquid density ratio Lambda=rhog/rhol is different from zero, tiny satellite bubbles may be formed as a result of the large gas velocities that are reached close to pinch-off. Moreover, we provide a closed expression for the characteristic satellite diameter, which decreases when decreasing Lambda and which shows order of magnitude agreement with the micron-sized satellite bubbles observed experimentally.

  13. On thermonuclear processes in cavitation bubbles

    NASA Astrophysics Data System (ADS)

    Nigmatulin, R. I.; Lahey, R. T., Jr.; Taleyarkhan, R. P.; West, C. D.; Block, R. C.

    2014-09-01

    The theoretical and experimental foundations of so-called bubble nuclear fusion are reviewed. In the nuclear fusion process, a spherical cavitation cluster ˜ 10-2 m in diameter is produced of spherical bubbles at the center of a cylindrical chamber filled with deuterated acetone using a focused acoustic field having a resonant frequency of about 20 kHz. The acoustically-forced bubbles effectuate volume oscillations with sharp collapses during the compression stage. At the final stages of collapse, the bubble cluster emits 2.5 MeV D-D fusion neutron pulses at a rate of ˜ 2000 per second. The neutron yield is ˜ 10^5 s -1. In parallel, tritium nuclei are produced at the same yield. It is shown numerically that, for bubbles having sufficient molecular mass, spherical shock waves develop in the center of the cluster and that these spherical shock waves (microshocks) produce converging shocks within the interior bubbles, which focus energy on the centers of the bubbles. When these shock waves reflect from the centers of the bubbles, extreme conditions of temperature ( ˜ 10^8 K) and density ( ˜ 10^4 kg m -3) arise in a (nano)spherical region ( ˜ 10-7 m in size) that last for ˜ 10-12 s, during which time about ten D-D fusion neutrons and tritium nuclei are produced in the region. A paradoxical result in our experiments is that it is bubble cluster (not streamer) cavitation and the sufficiently high molecular mass of (and hence the low sound speed in) D-acetone ( C3D6O) vapor (as compared, for example, to deuterated water D2O) which are necessary conditions for the formation of convergent spherical microshock waves in central cluster bubbles. It is these waves that allow the energy to be sufficiently focused in the nanospherical regions near the bubble centers for fusion events to occur. The criticism to which the concept of 'bubble fusion' has been subjected in the literature, in particular, most recently in Uspekhi Fizicheskikh Nauk (Physics - Uspekhi) journal, is

  14. Buoyancy Driven Shear Flows of Bubble Suspensions

    NASA Technical Reports Server (NTRS)

    Koch, D. L.; Hill, R. J.; Chellppannair, T.; Zenit, R.; Zenit, R.; Spelt, P. D. M.

    1999-01-01

    In this work the gas volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of bubble suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1a nd Re >> 1, for which comparisons are made with kinetic theory and numerical simulations. Here Re = gamma(a(exp 2)/nu is the Reynolds number and We = rho(gamma(exp 2))a(exp 3)/sigma is the Weber number; gamma is the shear rate, a is the bubble radius, nu is the kinematic viscosity of the liquid, rho is the density of the liquid, and sigma is the surface tension of the gas/liquid interface. Kang et al. calculated the bubble phase pressure and velocity variance of sheared bubble suspensions under conditions where the bubbles are spherical and the liquid phase velocity field can be approximated using potential flow theory, i.e. We= 0 and Re >> 1. Such conditions can be achieved in an experiment using gas bubbles, with a radius of O(0.5mm), in water. The theory requires that there be no average relative motion of the gas and liquid phases, hence the motivation for an experimental program in microgravity. The necessity of performing preliminary, Earth based experiments, however, requires performing experiments where the gas phase rises in the liquid, which significantly complicates the comparison of experiments with theory. Rather than comparing experimental results with theory for a uniform, homogeneous shear flow, experiments can be compared directly with solutions of the averaged equations of motion for bubble suspensions. This requires accounting for the significant lift force acting on the gas phase when the bubbles rise parallel to the average velocity of the sheared suspension. Shear flows can be produced in which the bubble phase pressure gradient, arising from shear induced collisions amongst the bubbles, balances a body force (centrifugal or gravitational) on the gas phase. A steady, non-uniform gas volume fraction

  15. Screening of liquids for thermocapillary bubble movement

    NASA Technical Reports Server (NTRS)

    Wilcox, W. R.; Subramanian, R. S.; Papazian, J. M.; Smith, H. D.; Mattox, D. M.

    1979-01-01

    Ground-based methods for pretesting qualitatively the thermocapillary movement of gas bubbles in a liquid to be used in space processing are discussed. Theoretical considerations are shown to require the use of a thin, enclosed, horizontal liquid film in order that the bubbles move faster than the bulk convection of the liquid, with insulating boundaries to prevent the onset of instabilities. Experimental realizations of horizontal cells in which to test the thermocapillary movement of bubbles in sheets of molten glass heated from below and organic melts in tubes heated from both ends are briefly described and the results of experiments are indicated.

  16. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2016-06-07

    it is fairly easy to show that R ~ eat (a = S/ρg), i.e. exponential growth , which is a far faster than has been suggested previously. We expect this...Gas Bubble Growth in Muddy Sediments Bernard P. Boudreau Department of Oceanography Dalhousie University Halifax, Nova Scotia B3H 4J1, Canada phone...objective is a working model for the growth of a single, isolated bubble in a marine sediment, validated with bubble growth data obtained in laboratory

  17. Burst of Star Formation Drives Galactic Bubble

    NASA Technical Reports Server (NTRS)

    2001-01-01

    NASA's Hubble Space Telescope (HST) captures a lumpy bubble of hot gas rising from a cauldron of glowing matter in Galaxy NGC 3079, located 50 million light-years from Earth in the constellation Ursa Major. Astronomers suspect the bubble is being blown by 'winds' or high speed streams of particles, released during a burst of star formation. The bubble's lumpy surface has four columns of gaseous filaments towering above the galaxy's disc that whirl around in a vortex and are expelled into space. Eventually, this gas will rain down on the disc and may collide with gas clouds, compress them, and form a new generation of stars.

  18. Liquid jet pumped by rising gas bubbles

    NASA Technical Reports Server (NTRS)

    Hussain, N. A.; Siegel, R.

    1975-01-01

    A two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. Bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they rise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature.

  19. Numerical investigation of bubble nonlinear dynamics characteristics

    SciTech Connect

    Shi, Jie Yang, Desen; Shi, Shengguo; Hu, Bo; Zhang, Haoyang; Jiang, Wei

    2015-10-28

    The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.

  20. Bubble Formation Modeling in IE-911

    SciTech Connect

    Fondeur, F.F.

    2000-09-27

    The author used diffusion modeling to determine the hydrogen and oxygen concentration inside IE-911. The study revealed gas bubble nucleation will not occur in the bulk solution inside the pore or on the pore wall. This finding results from the fast oxygen and hydrogen gas molecular diffusion and a very confined pore space. The net steady state concentration of these species inside the pore proves too low to drive bubble nucleation. This study did not investigate other gas bubble nucleating mechanism such as suspended particles in solution.

  1. Interactions of multiple spark-generated bubbles with phase differences

    NASA Astrophysics Data System (ADS)

    Fong, Siew Wan; Adhikari, Deepak; Klaseboer, Evert; Khoo, Boo Cheong

    2009-04-01

    This paper aims to study the complex interaction between multiple bubbles, and to provide a summary and physical explanation of the phenomena observed during the interaction of two bubbles. High-speed photography is utilized to observe the experiments involving multiple spark-generated bubbles. Numerical simulations corresponding to the experiments are performed using the Boundary Element Method (BEM). The bubbles are typically between 3 and 5 mm in radius and are generated either in-phase (at the same time) or with phase differences. Complex phenomena are observed such as bubble splitting, and high-speed jetting inside a bubble caused by another collapsing bubble nearby (termed the ‘catapult’ effect). The two-bubble interactions are broadly classified in a graph according to two parameters: the relative inter-bubble distance and the phase difference (a new parameter introduced). The BEM simulations provide insight into the physics, such as bubble shape changes in detail, and jet velocities. Also presented in this paper are the experimental results of three bubble interactions. The interesting and complex observations of multiple bubble interaction are important for a better understanding of real life applications in medical ultrasonic treatment and ultrasonic cleaning. Many of the three bubble interactions can be explained by isolating bubble pairs and classifying their interaction according to the graph for the two bubble case. This graph can be a useful tool to predict the behavior of multiple bubble interactions.

  2. Generation of pulsed discharge plasma in water with fine bubbles

    NASA Astrophysics Data System (ADS)

    Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu; Goto laboratory Team

    2015-09-01

    Recently, some researchers have proposed electric discharge methods with bubbles in water because the discharge plasma inside bubble was easy to be generated compared to that in water. Almost all of these methods introduced bubbles in the order of millimeter size from a nozzle placed in water. In these methods, bubbles rose one after another owing to high rising speed of millibubble, leading to inefficient gas consumption. We proposed fine bubbles introduction at the discharge area in water. A fine bubble is determined a bubble with less than 100 μm in a diameter. Fine bubbles exhibit extremely slow rising speed. Fine bubbles decrease in size during bubble rising and subsequently collapse in water with OH radical generation. Therefore, combining the discharge plasma with fine bubbles is expected to generate more active species with small amount of gas consumption. In this work, fine bubbles were introduced in water and pulsed discharge plasma was generated between two cylindrical electrodes which placed in water. We examined effects of fine bubbles on electric discharge in water when argon or oxygen gas was utilized as feed gas. Fine bubbles enhanced optical emission of hydrogen and oxygen atoms from H2O molecules, but that of feed gas was not observed. The formation mechanism of H2O2 by electric discharge was supposed to be different from that with no bubbling. Dissolved oxygen in water played a role in H2O2 formation by the discharge with fine bubbles.

  3. Bubbles, Bubbles, Tremors & Trouble: The Bayou Corne Sinkhole

    NASA Astrophysics Data System (ADS)

    Nunn, J. A.

    2013-12-01

    In May 2012, thermogenic methane bubbles were first observed in Bayou Corne in Assumption Parish, Louisiana. As of July 2013, ninety one bubbling sites have been identified. Gas was also found in the top of the Mississippi River Alluvial Aquifer (MRAA) about 125 ft below the surface. Vent wells drilled into the MRAA have flared more 16 million SCF of gas. Trace amounts of hydrogen sulfide also have been detected. Bayou Corne flows above the Napoleonville salt dome which has been an active area for oil and gas exploration since the 1920s. The dome is also a site of dissolution salt mining which has produced large caverns with diameters of up to 300 ft and heights of 2000 ft. Some caverns are used for storage of natural gas. Microseismic activity was confirmed by an Earthscope seismic station in White Castle, LA in July 2012. An array of microseismic stations set up in the area recorded more than 60 microseismic events in late July and early August, 2012. These microseismic events were located on the western side of the dome. Estimated focal depths are just above the top of salt. In August 2012, a sinkhole developed overnight just to the northwest of a plugged and abandoned brine filled cavern (see figure below). The sinkhole continues to grow in area to more than 20 acres and has consumed a pipeline right of way. The sinkhole is more than 750 ft deep at its center. Microseismic activity was reduced for several months following the formation of the sinkhole. Microseismic events have reoccurred episodically since then with periods of frequent events preceding slumping of material into the sinkhole or a 'burp' where fluid levels in the sinkhole drop and then rebound followed by a decrease in microseismic activity. Some gas and/or oil may appear at the surface of the sinkhole following a 'burp'. Very long period events also have been observed which are believed to be related to subsurface fluid movement. A relief well drilled into the abandoned brine cavern found that

  4. Bubbles and mismatches in DNA melting

    NASA Astrophysics Data System (ADS)

    Zeng, Yan

    We obtained the first experimental measurements of the length of the denaturation bubble appearing in the DNA melting transition. This is achieved by working with short oligomers which can form only one bubble per molecule. We used sequences clamped at the ends with GC pairs (strong binding) and possessing AT rich (weaker binding) middle regions in order to have the bubble open in the middle, and sequences with GC pairs at one end and AT pairs at the other end in order to form the bubble at the end. Use a quenching technique to trap the bubble states, we could measure the length of the bubble and the relative weights of the bubble states as a function of temperature. We found that the average bubble size <ℓ> grows for increasing temperature, but reaches a plateau at a length of order B (the length of the AT region). After the plateau, the average bubble length jumps to 1. This jump of the order parameter is a signature of a discontinuous transition, one where the bubble size remains finite up to critical temperature of strand separation. When B increases, the extension of the plateau shrinks. This suggests a continuous transition for a homogenous sequence (e.g. all AT base pairs) in the thermodynamic limit. The presence of the bubble states decreases as B is reduced. By plotting the average statistical weight of the bubble states vs. B, we obtained the first direct measurement of the nucleation size of the bubble. For a bubble flanked by double-stranded regions, the nucleation size is ˜ 3 bases. For bubbles opening at the ends of the molecule there is no nucleation threshold. The measured statistical weights of the bubble states agree with the predictions of the widely used thermodynamic models in the case of unzipping from the ends; however, internal bubble states are not completely described by the model. For the first time we show experimentally that a single mismatch transforms a transition with many intermediates into a nearly two-state transition for

  5. Time-Dependent Changes in a Shampoo Bubble

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Arun

    2000-10-01

    This article demonstrates the fascinating phenomenon of time evolution of a shampoo bubble through experiments that can be performed by undergraduate students. The changes in thickness of the bubble films with time are followed by UV-vis spectroscopy. The change in chemical composition as a bubble film evolves is monitored by FTIR spectroscopy. It is observed that the change in thickness of a typical shampoo bubble film enclosed in a container is gradual and slow, and the hydrocarbon components of the bubble drain from the bubble much more slowly than water. An additional agent, such as acetonitrile, strikingly alters the dynamics of evolution of such a bubble.

  6. [First aid to persons with explosion trauma].

    PubMed

    Shapovalov, V M; Samokhvalov, I M

    2012-10-01

    Modern organization providing medical aid to victims of explosion trauma in peace time, the success of which largely depends on the timely and professional interaction among the structures involeved into emergency relief operation is represented in the article. Content and sequence of events providing emergency medical and first medical aid to victims of the explosions, and the appropriateness of allocation affected groups, based on the predicted effectiveness of medical care is analyzed. The algorithm, currently used by ambulance crews, of assistance to victims with explosion and order evacuations is analyzed. The content of therapeutic measures in receipt of the wounded on the steps of skilled and specialized surgical care in accordance with the idea of a separation surgery on three stages (damage control). The content of the main levels of damage control orthopedics is introduced.

  7. Evolution of a Collection of Bubbles with Application to Wakes, Bubble Screens, and Cloud Noise

    DTIC Science & Technology

    1994-08-01

    bubble approaches the axis in a spiral fashion. The above reasoning allows one to define a "violent capture radius" around the vortex which is bubble...plane at different instants. The observer is looking down on the XOY plane from very far on the Z axis. The bubble is seen spiraling around the vortex ...a path similar to the classical logarithmic spiral , A and B can follow more complicated paths, even moving away from the vortex axis at some point in

  8. Black Hole Blows Big Bubble

    NASA Astrophysics Data System (ADS)

    2010-07-01

    Combining observations made with ESO's Very Large Telescope and NASA's Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. This object, also known as a microquasar, blows a huge bubble of hot gas, 1000 light-years across, twice as large and tens of times more powerful than other known microquasars. The discovery is reported this week in the journal Nature. "We have been astonished by how much energy is injected into the gas by the black hole," says lead author Manfred Pakull. "This black hole is just a few solar masses, but is a real miniature version of the most powerful quasars and radio galaxies, which contain black holes with masses of a few million times that of the Sun." Black holes are known to release a prodigious amount of energy when they swallow matter. It was thought that most of the energy came out in the form of radiation, predominantly X-rays. However, the new findings show that some black holes can release at least as much energy, and perhaps much more, in the form of collimated jets of fast moving particles. The fast jets slam into the surrounding interstellar gas, heating it and triggering an expansion. The inflating bubble contains a mixture of hot gas and ultra-fast particles at different temperatures. Observations in several energy bands (optical, radio, X-rays) help astronomers calculate the total rate at which the black hole is heating its surroundings. The astronomers could observe the spots where the jets smash into the interstellar gas located around the black hole, and reveal that the bubble of hot gas is inflating at a speed of almost one million kilometres per hour. "The length of the jets in NGC 7793 is amazing, compared to the size of the black hole from which they are launched," says co-author Robert Soria [1]. "If the black hole were shrunk to the size of a soccer ball, each jet would extend from the Earth to beyond the orbit of Pluto." This research will help

  9. Black Hole Blows Big Bubble

    NASA Astrophysics Data System (ADS)

    2010-07-01

    Combining observations made with ESO's Very Large Telescope and NASA's Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. This object, also known as a microquasar, blows a huge bubble of hot gas, 1000 light-years across, twice as large and tens of times more powerful than other known microquasars. The discovery is reported this week in the journal Nature. "We have been astonished by how much energy is injected into the gas by the black hole," says lead author Manfred Pakull. "This black hole is just a few solar masses, but is a real miniature version of the most powerful quasars and radio galaxies, which contain black holes with masses of a few million times that of the Sun." Black holes are known to release a prodigious amount of energy when they swallow matter. It was thought that most of the energy came out in the form of radiation, predominantly X-rays. However, the new findings show that some black holes can release at least as much energy, and perhaps much more, in the form of collimated jets of fast moving particles. The fast jets slam into the surrounding interstellar gas, heating it and triggering an expansion. The inflating bubble contains a mixture of hot gas and ultra-fast particles at different temperatures. Observations in several energy bands (optical, radio, X-rays) help astronomers calculate the total rate at which the black hole is heating its surroundings. The astronomers could observe the spots where the jets smash into the interstellar gas located around the black hole, and reveal that the bubble of hot gas is inflating at a speed of almost one million kilometres per hour. "The length of the jets in NGC 7793 is amazing, compared to the size of the black hole from which they are launched," says co-author Robert Soria [1]. "If the black hole were shrunk to the size of a soccer ball, each jet would extend from the Earth to beyond the orbit of Pluto." This research will help

  10. [Geriatric trauma centers - requirements catalog. An initiative to promote and guarantee the quality of care of elderly trauma patients receiving inpatient care].

    PubMed

    Gogol, M; van den Heuvel, D; Lüttje, D; Püllen, R; Reingräber, A C; Schulz, R-J; Veer, A; Wittrich, A

    2014-06-01

    For the care of the elderly, specific geriatric care facilities in hospitals and specialized rehabilitation centers have been established in the last 20 years throughout Germany. In addition, trauma surgery departments in hospitals and clinics also provide comprehensive care for trauma patients. The present requirements catalog was developed with the aim to ensure the standardization and quality assurance of these care facilities. Thus, the structural basics and, in particular, the structured cooperation between geriatrics and trauma surgery are described and defined in terms of structure, process, and outcome quality. The Bundesverband Geriatrie, the Deutsche Gesellschaft für Geriatrie, and the Deutsche Gesellschaft für Gerontologie und Geriatrie offer documentation for external and internal use and evaluation of the structures and processes for certification of geriatric trauma centers. Prerequisite for certification is to meet the technical requirements defined in the requirements catalogue or documents derived from it, and proof of a quality management system according to ISO 9001.

  11. Warfare facial trauma: who will treat?

    PubMed

    Holmes, D K

    1996-09-01

    Most of the facial trauma in the United States is treated in trauma centers in large urban or university medical centers, with limited trauma care taking place in our military medical treatment facilities. In many cases, active duty facial trauma surgeons may lack the current experience necessary for the optimal care of facial wounds of our inquired military personnel in the early stages of the conflict. Consequently, the skills of the reservist trauma surgeons who staff our civilian trauma centers and who care for facial trauma victims daily will be critical in caring for our wounded. These "trauma-current" reservists may act as a cadre of practiced surgeons to aid those with less experience. A plan for refresher training of active duty facial trauma surgeons is presented.

  12. Trauma Training and Workload: A National Survey.

    PubMed

    McSorley, K; Quinlan, J

    2015-09-01

    Trauma is a major source of mortality and morbidity throughout Ireland. Training in trauma is dependant on experience gained by trainees within specific posts. Trauma services are a topical issue at present with much discussion about delivery and restructuring. With this in mind we conducted an online survey of trainees in emergency medicine, orthopaedic and general surgery to assess current experience and opinions with regard to trauma. The survey was vetted and distributed by the relevant training bodies. 59(98.33%) respondents believed smaller units should be bypassed for major trauma and 55 (91.67%) believed that larger hospitals receiving major trauma should have a trauma theatre available 24-hours a day. 55 (91.67%) also foresaw themselves covering major trauma as consultants, consequently these trainees will be the consultants developing, moulding and working in this restructured trauma service.

  13. How are soap bubbles blown? Fluid dynamics of soap bubble blowing

    NASA Astrophysics Data System (ADS)

    Davidson, John; Lambert, Lori; Sherman, Erica; Wei, Timothy; Ryu, Sangjin

    2013-11-01

    Soap bubbles are a common interfacial fluid dynamics phenomenon having a long history of delighting not only children and artists but also scientists. In contrast to the dynamics of liquid droplets in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented. This is possibly because studying soap bubbles is more challenging due to there existing two gas-liquid interfaces. Having the thin-film interface seems to alter the characteristics of the bubble/drop creation process since the interface has limiting factors such as thickness. Thus, the main objective of this study is to determine how the thin-film interface differentiates soap bubbles from gas bubbles and liquid drops. To investigate the creation process of soap bubbles, we constructed an experimental model consisting of air jet flow and a soap film, which consistently replicates the conditions that a human produces when blowing soap bubbles, and examined the interaction between the jet and the soap film using the high-speed videography and the particle image velocimetry.

  14. A study of laser-induced bubbles in cryogenic fluid - Behavior of bubbles in liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Maeno, Kazuo; Yokoyama, Shingo; Hanaoka, Yutaka

    The dynamics of cavitation vapor bubble in cryogenic liquid nitrogen is investigated experimentally and analytically. The bubbles are produced by focusing a giant pulse of Q-switched ruby laser into the liquid nitrogen in a cryostat, and the dynamics of the laser-induced bubble are studied by means of high-speed photography by using an image converter camera with the framing rates of 100,000 frames/s. A numerical analysis is also performed on the behavior of a bubble in cryogenic liquid. The mathematical formulation takes into account the effect of liquid inertia (incompressible liquid), nonequilibrium condensation of the vapor in the bubble, and the heat transfer at the bubble wall. The experimental data on the bubble motion in liquid nitrogen under the near-equilibrium initial conditions with an atmospheric pressure are compared to the numerical solutions. The bubble motion observed indicates more violent and decaying behavior than the estimated tendency. The heat and mass transfer effects including the evaporation and condensation phenomena have strong influence on the vapor bubble motion in cryogenic liquid. Qualitatively, the numerical analysis can simulate the experimental results.

  15. Determining the bubble cap film thickness of bursting bubbles from their acoustic emissions.

    PubMed

    Deane, Grant B

    2013-02-01

    A study of the sound generated by 2.5 mm radius bubbles bursting on the surface of fresh water is presented. The sound pulses are found to be sensitive to the time interval between the bubble reaching the water surface and bursting. Bubbles that burst within a few 10's of milliseconds behave like a Helmholtz resonator and radiate a swept chirp pulse. Bubbles that persist for 100's of milliseconds or more exhibit more complex acoustic behavior. An analysis of the resonator behavior provides an estimate of the film thickness in reasonable agreement with a fluid drainage model.

  16. Heat transfer and bubble dynamics in slurry bubble columns for Fischer-Tropsch clean alternative energy

    NASA Astrophysics Data System (ADS)

    Wu, Chengtian

    With the increasing demand for alternative energy resources, the Fischer-Tropsch (FT) process that converts synthesis gas into clean liquid fuels has attracted more interest from the industry. Slurry bubble columns are the most promising reactors for FT synthesis due to their advantages over other reactors. Successful operation, design, and scale-up of such reactors require detailed knowledge of hydrodynamics, bubble dynamics, and transport characteristics. However, most previous studies have been conducted at ambient pressure or covered only low superficial gas velocities. The objectives of this study were to experimentally investigate the heat transfer coefficient and bubble dynamics in slurry bubble columns at conditions that can mimic FT conditions. The air-C9C 11-FT catalysts/glass beads systems were selected to mimic the physical properties of the gas, liquid, and solid phases at commercial FT operating conditions. A heat transfer coefficient measurement technique was developed, and for the first time, this technique was applied in a pilot scale (6-inch diameter) high pressure slurry bubble column. The effects of superficial gas velocity, pressure, solids loading, and liquid properties on the heat transfer coefficients were investigated. Since the heat transfer coefficient can be affected by the bubble properties (Kumar et al., 1992), in this work bubble dynamics (local gas holdup, bubble chord length, apparent bubble frequency, specific interfacial area, and bubble velocity) were studied using the improved four-point optical probe technique (Xue et al., 2003; Xue, 2004). Because the four-point optical technique had only been successfully applied in a churn turbulent flow bubble column (Xue, 2004), this technique was first assessed in a small scale slurry bubble column in this study. Then the bubble dynamics were studied at the same conditions as the heat transfer coefficient investigation in the same pilot scale column. The results from four-point probe

  17. Population Balance Modeling of Polydispersed Bubbly Flow in Continuous-Casting Using Multiple-Size-Group Approach

    NASA Astrophysics Data System (ADS)

    Liu, Zhongqiu; Li, Linmin; Qi, Fengsheng; Li, Baokuan; Jiang, Maofa; Tsukihashi, Fumitaka

    2015-02-01

    A population balance model based on the multiple-size-group (MUSIG) approach has been developed to investigate the polydispersed bubbly flow inside the slab continuous-casting mold and bubble behavior including volume fraction, breakup, coalescence, and size distribution. The Eulerian-Eulerian approach is used to describe the equations of motion of the two-phase flow. All the non-drag forces (lift force, virtual mass force, wall lubrication force, and turbulent dispersion force) and drag force are incorporated in this model. Sato and Sekiguchi model is used to account for the bubble-induced turbulence. Luo and Svendsen model and Prince and Blanch model are used to describe the bubbles breakup and coalescence behavior, respectively. A 1/4th water model of the slab continuous-casting mold was applied to investigate the distribution and size of bubbles by injecting air through a circumferential inlet chamber which was made of the specially-coated samples of mullite porous brick, which is used for the actual upper nozzle. Against experimental data, numerical results showed good agreement for the gas volume fraction and local bubble Sauter mean diameter. The bubble Sauter mean diameter in the upper recirculation zone decreases with increasing water flow rate and increases with increasing gas flow rate. The distribution of bubble Sauter mean diameter along the width direction of the upper mold increases first, and then gradually decreases from the SEN to the narrow wall. Close agreements between the predictions and measurements demonstrate the capability of the MUSIG model in modeling bubbly flow inside the continuous-casting mold.

  18. Sonochemical effects on single-bubble sonoluminescence

    NASA Astrophysics Data System (ADS)

    Yuan, Li

    2005-10-01

    A refined hydrochemical model for single-bubble sonoluminescence (SBSL) is presented. The processes of water vapor evaporation and condensation, mass diffusion, and chemical reactions are taken into account. Numerical simulations of Xe-, Ar- and He-filled bubbles are carried out. The results show that the trapped water vapor in conjunction with its endothermic chemical reactions significantly reduces the temperature within the bubble so that the degrees of ionization are generally very low. The chemical radicals generated from water vapor are shown to play an increasingly important role in the light emission from Xe to He bubbles. Light spectra and pulses are then computed from an optically thin model. It is found that the resulting spectrum intensities are too small and the pulse widths are too short to fit to recent experimental results within stable SBSL range. Addition of a finite-size blackbody core to the optically thin model improves the fitting. Suggestions on how to reconcile the conflict are given.

  19. Chemical Reactions in a Sonoluminescing Bubble

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    1997-09-01

    Rates of chemical reactions in an air bubble are calculatednumerically under a condition of the single-bubble sonoluminescence(SBSL) and that of non-light-emission. In the calculations, effect of non-equilibrium evaporation and condensationof water vapor at the bubble wall andthat of thermal conduction both inside and outside the bubbleare taken into account.Numerical calculations reveal that appreciable amounts of OH, H2O2, HO2, O3, H2, H, and O moleculesare created in a bubble under the condition of SBSL.The amounts of chemical products containing nitrogen such as NOx, NHx, and HNOx are much less than those of the above products at least in the first few acoustic cycles.Numerical calculations also reveal that no chemical reactionstake place under a condition of non-light-emission.Connection with sonoluminescence is also discussed.

  20. Sonochemical effects on single-bubble sonoluminescence.

    PubMed

    Yuan, Li

    2005-10-01

    A refined hydrochemical model for single-bubble sonoluminescence (SBSL) is presented. The processes of water vapor evaporation and condensation, mass diffusion, and chemical reactions are taken into account. Numerical simulations of Xe-, Ar- and He-filled bubbles are carried out. The results show that the trapped water vapor in conjunction with its endothermic chemical reactions significantly reduces the temperature within the bubble so that the degrees of ionization are generally very low. The chemical radicals generated from water vapor are shown to play an increasingly important role in the light emission from Xe to He bubbles. Light spectra and pulses are then computed from an optically thin model. It is found that the resulting spectrum intensities are too small and the pulse widths are too short to fit to recent experimental results within stable SBSL range. Addition of a finite-size blackbody core to the optically thin model improves the fitting. Suggestions on how to reconcile the conflict are given.

  1. Bubble collisions and measures of the multiverse

    SciTech Connect

    Salem, Michael P.

    2012-01-01

    To compute the spectrum of bubble collisions seen by an observer in an eternally-inflating multiverse, one must choose a measure over the diverging spacetime volume, including choosing an ''initial'' hypersurface below which there are no bubble nucleations. Previous calculations focused on the case where the initial hypersurface is pushed arbitrarily deep into the past. Interestingly, the observed spectrum depends on the orientation of the initial hypersurface, however one's ability observe the effect rapidly decreases with the ratio of inflationary Hubble rates inside and outside one's bubble. We investigate whether this conclusion might be avoided under more general circumstances, including placing the observer's bubble near the initial hypersurface. We find that it is not. As a point of reference, a substantial appendix reviews relevant aspects of the measure problem of eternal inflation.

  2. Observable effects of anisotropic bubble nucleation

    SciTech Connect

    Blanco-Pillado, Jose J.; Salem, Michael P. E-mail: salem@cosmos.phy.tufts.edu

    2010-07-01

    Our universe may have formed via bubble nucleation in an eternally-inflating background. Furthermore, the background may have a compact dimension — the modulus of which tunnels out of a metastable minimum during bubble nucleation — which subsequently grows to become one of our three large spatial dimensions. Then the reduced symmetry of the background is equivalent to anisotropic initial conditions in our bubble universe. We compute the inflationary spectrum in such a scenario and, as a first step toward understanding the effects of anisotropy, project it onto spherical harmonics. The resulting spectrum exhibits anomalous multipole correlations, their relative amplitude set by the present curvature parameter, which appear to extend to arbitrarily large multipole moments. This raises the possibility of future detection, if slow-roll inflation does not last too long within our bubble. A full understanding of the observational signal must account for the effects of background anisotropy on photon free streaming, and is left to future work.

  3. Shapes of Bubbles and Drops in Motion.

    ERIC Educational Resources Information Center

    O'Connell, James

    2000-01-01

    Explains the shape distortions that take place in fluid packets (bubbles or drops) with steady flow motion by using the laws of Archimedes, Pascal, and Bernoulli rather than advanced vector calculus. (WRM)

  4. Liquid jet pumped by rising gas bubbles

    NASA Technical Reports Server (NTRS)

    Hussain, N. A.; Siegel, R.

    1975-01-01

    From observations of a stream of gas bubbles rising through a liquid, a two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. The bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they arise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature.

  5. Interaction effects in thermocapillary bubble migration

    NASA Technical Reports Server (NTRS)

    Meyyappan, M.; Wilcox, W. R.; Subramanian, R. S.

    1982-01-01

    Two bubbles migrating along their line of centers under the influence of an imposed thermal gradient are considered in the quasi-static limit. Results are reported for representative values of the governing parameters.

  6. Stretching cells and delivering drugs with bubbles

    NASA Astrophysics Data System (ADS)

    Ohl, Claus-Dieter; Li, Fenfang; Chon U, Chan; Gao, Yu; Xu, Chenjie

    2015-11-01

    In this talk we'll review our work on impulsive cell stretching using cavitation bubbles and magnetic microbubbles for drug delivery. For sufficient short times cells can sustain a much larger areal strain than the yield strain obtained from quasi-static stretching. Experiments with red blood cells show that even then the rupture of the cell is slow process; it is caused by diffusive swelling rather than mechanical violation of the plasma membrane. In the second part we'll discuss bubbles coated with magnetic and drug loaded particles. These bubbles offer an interesting vector for on demand delivery of drugs using mild ultrasound and magnetic fields. We report on basic experiments in microfluidic channels revealing the release of the agent during bubble oscillations and first in vivo validation with a mouse tumor model. Singapore National Research Foundations Competitive Research Program funding (NRF-CRP9-2011-04).

  7. Are there really bubbles in oil prices?

    NASA Astrophysics Data System (ADS)

    Balcilar, Mehmet; Ozdemir, Zeynel Abidin; Yetkiner, Hakan

    2014-12-01

    The aim of this paper is to identify bubbles in oil prices by using the “exponential fitting” methodology proposed by Watanabe et al. (2007) [28,29]. We use the daily US dollar closing crude oil prices of West Texas Intermediate (WTI) covering the 1986:01:02-2013:07:09 and the Brent for the 1987:05:20-2013:07:09 periods. The distinguishing feature of this study from the previous studies is that this is the first study in the literature showing the existence of bubbles in crude oil prices. We found that there are four distinct periods of persistent bubbles in the crude oil prices since 1986. Two of these persistent bubbles are before 2000 and two of them are after 2000. We conclude that further research is needed to understand better how futures markets may impact the oil price formation.

  8. Fermi discovers giant bubbles in Milky Way

    NASA Video Gallery

    Using data from NASA's Fermi Gamma-ray Space Telescope, scientists have recently discovered a gigantic, mysterious structure in our galaxy. This feature looks like a pair of bubbles extending above...

  9. On the shape of giant soap bubbles.

    PubMed

    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.

  10. Experimental study on interaction and coalescence of synchronized multiple bubbles

    NASA Astrophysics Data System (ADS)

    Cui, P.; Wang, Q. X.; Wang, S. P.; Zhang, A. M.

    2016-01-01

    Experiments are carried out on the interaction and coalescence of two, three, and four bubbles with approximately the same sizes, distributed evenly and symmetrically. The bubbles are generated simultaneously by electric discharges, using an in-house designed series circuit, and their interaction is captured using a high-speed camera. Particular attentions are paid to if/when coalescence of bubbles happens and the motion of the joined bubbles. Some new features are observed, which depend mainly on the dimensionless distance γbb = dbb/Rmax, where dbb is the inter-bubble distance and Rmax is the maximum bubble radius. For γbb > 2, a jet forms and penetrates each side bubble, directed to the center of the configuration, resulting in a protrusion. Towards the end of collapse, a large portion of bubble gases is compressed into the protrusion from the main part of the toroidal bubble. For γbb < 2, the bubbles coalesce during expansion, and the part of the joined bubble's surface distal from the center of the configuration collapses faster than elsewhere. The experiments show that the oscillation period of multi-bubbles does not change appreciably without coalescence but increases significantly with coalescence. For three bubbles initiated at collinear positions with γbb > 2, the jets that form from the side bubbles are towards the middle, and the middle bubble splits into two parts, moving towards the two side bubbles. For γbb < 2, the side bubbles merge with the middle bubble during expansion, forming an ellipsoid bubble; the joined bubble collapses predominantly from two sides, where two inward jets form towards the end of collapse.

  11. Methane bubbling: from speculation to quantification

    NASA Astrophysics Data System (ADS)

    Grinham, A. R.; Dunbabin, M.; Yuan, Z.

    2013-12-01

    Rates of methane bubbling (ebullition) represent a notoriously difficult emission pathway to quantify with highly variable spatial and temporal changes. However, the importance of bubbling fluxes in terms of total emissions is increasingly recognised from a number of different globally relevant natural systems including lakes, reservoirs and wetlands. This represents a critical challenge to current survey efforts to quantify greenhouse gas emissions and reduce the uncertainty associated with bubbling fluxes. A number of different methods have been proposed to overcome this challenge including bubble traps, floating chambers, echo sounders, laser spectrography and camera systems. Each method has relative merits and deficiencies with all trading-off the ability to directly quantify methane and provide spatial and temporal coverage. Here we present a novel method that allows direct measurement of methane bubble concentration as well as the ability to persistently monitor a wide spatial area. Central to the monitoring system is an Autonomous Surface Vessel (ASV) and an Optical Methane Detector (OMD). The ASV is equipped with solar panels and uses electric motors for propulsion to allow persistent environmental monitoring. The OMD has a path length of 1.3 m and 7 Hz sampling so a typical mission of 3 hours at 1 m s-1 covers an area in excess of 10 000 m2 and over 65 000 data points. The system was assessed on four sub-tropical freshwater reservoirs of varying surface area (0.5 to 100 km2), age (2 to 65 y) and catchment land use (40 to 90% natural vegetation cover). Each reservoir had unique challenges in terms of navigation and field conditions to test feasibility of this method. Deployment length varied from a single day to over 4 months to test method durability. In addition to ASV bubble surveys, floating static chambers were deployed to determine diffusive fluxes. Localised instantaneous bubble flux rates within a single reservoir ranged over three orders of

  12. Peritraumatic dissociative experiences, trauma narratives, and trauma pathology.

    PubMed

    Zoellner, Lori A; Alvarez-Conrad, Jennifer; Foa, Edna B

    2002-02-01

    Peritraumatic dissociation, i.e., dissociation during or immediately after a traumatic event, has been associated with persistence of trauma-related pathology. Peritraumatic dissociation may interfere with encoding of traumatic memories and this style may impede recovery. This study examines this hypothesis by analyzing trauma narratives from 28 female sexual and nonsexual assault victims who reported either high or low peritraumatic dissociation. Participants were asked to recount their assault. Narratives were videotaped, transcribed, and coded. Narratives of individuals with high peritraumatic dissociation had higher grade levels and a trend toward lower reading ease than those with low peritraumatic dissociation. Both higher grade levels and lower reading ease of prethreat sections of trauma narratives were related to posttreatment reexperiencing and anxiety symptoms.

  13. Shock Propagation and Attenuation in Bubbly Liquids

    DTIC Science & Technology

    1998-01-01

    mixture. Since the bubble radii satisfy the Rayleigh - Plesset equation which is a second-order ODE relating the radius and its first two time...instance, if allowance for relative motion between the two phases is made, the pressure is found to depend on both the mixture density and the number...their first two substantial time derivatives, taken with respect to the velocity of the bubble phase . We thus need an additional relationship between the

  14. Astronaut Pedro Duque Watches A Water Bubble

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Aboard the International Space Station (ISS), European Space Agency astronaut Pedro Duque of Spain watches a water bubble float between a camera and himself. The bubble shows his reflection (reversed). Duque was launched aboard a Russian Soyuz TMA-3 spacecraft from the Baikonur Cosmodrome, Kazakhstan on October 18th, along with expedition-8 crew members Michael C. Foale, Mission Commander and NASA ISS Science Officer, and Cosmonaut Alexander Y. Kaleri, Soyuz Commander and flight engineer.

  15. Gravity waves from cosmic bubble collisions

    SciTech Connect

    Salem, Michael P.; Saraswat, Prashant; Shaghoulian, Edgar E-mail: ps88@stanford.edu

    2013-02-01

    Our local Hubble volume might be contained within a bubble that nucleated in a false vacuum with only two large spatial dimensions. We study bubble collisions in this scenario and find that they generate gravity waves, which are made possible in this context by the reduced symmetry of the global geometry. These gravity waves would produce B-mode polarization in the cosmic microwave background, which could in principle dominate over the inflationary background.

  16. A simple circuit to deliver bubbling CPAP.

    PubMed

    Kaur, Charanjit; Sema, Akatoli; Beri, Rajbir S; Puliyel, Jacob M

    2008-04-01

    Nasal continuous positive airway pressure (CPAP), especially bubbling CPAP, is known to reduce the need for more invasive ventilation. We here describe a circuit that can deliver bubbling CPAP in resource poor settings. We describe how the oxygen concentration can be altered from 98% to 21% oxygen using this system. Addition of a humidifier in the circuit has the effect of reducing the oxygen concentration by 1 to 5%. The cost of putting together the system is approximately Rs 5000.

  17. Beer tapping: dynamics of bubbles after impact

    NASA Astrophysics Data System (ADS)

    Mantič-Lugo, V.; Cayron, A.; Brun, P.-T.; Gallaire, F.

    2015-12-01

    Beer tapping is a well known prank where a bottle of beer is impacted from the top by a solid object, usually another bottle, leading to a sudden foam overflow. A description of the shock-driven bubble dynamics leading to foaming is presented based on an experimental and numerical study evoking the following physical picture. First, the solid impact produces a sudden downwards acceleration of the bottle creating a strong depression in the liquid bulk. The existing bubbles undergo a strong expansion and a sudden contraction ending in their collapse and fragmentation into a large amount of small bubbles. Second, the bubble clouds present a large surface area to volume ratio, enhancing the CO2 diffusion from the supersaturated liquid, hence growing rapidly and depleting the CO2. The clouds of bubbles migrate upwards in the form of plumes pulling the surrounding liquid with them and eventually resulting in the foam overflow. The sudden pressure drop that triggers the bubble dynamics with a collapse and oscillations is modelled by the Rayleigh-Plesset equation. The bubble dynamics from impact to collapse occurs over a time (tb ≃ 800 μs) much larger than the acoustic time scale of the liquid bulk (tac = 2H/c ≃ 80 μs), for the experimental container of height H = 6 cm and a speed of sound around c ≃ 1500 m/s. This scale separation, together with the comparison of numerical and experimental results, suggests that the pressure drop is controlled by two parameters: the acceleration of the container and the distance from the bubble to the free surface.

  18. Gravity Wave Generation by Largescale Bubbles

    NASA Astrophysics Data System (ADS)

    Brandenburg, A.

    The response of an isothermal atmosphere to small disturbances in entropy is studied taking compressible effects fully into account. The method of Green's functions is applied to solve the linearized hydrodynamic equations by Fourier transformation. A bubble may be created by perturbing the entropy within a finite volume. At first Lamb waves will be then emitted radially and the bubble undergoes a series of Brunt-Väisälä oscillations.

  19. Integral momentum balance on a growing bubble

    NASA Astrophysics Data System (ADS)

    Siedel, S.; Cioulachtjian, S.; Robinson, A. J.; Bonjour, J.

    2013-12-01

    The integral momentum balance on a growing boiling bubble is investigated. All forces acting on the bubble are detailed, and the methods and assumptions used to calculate their integral resultants are discussed. The momentum balance computation is then performed using experimental data of bubbles growing on an artificial nucleation site in a controlled environment. The relative magnitude of each force component is compared, showing negligible dynamic forces, upwards forces composed mainly of the buoyancy and contact pressure components, and downwards forces being exclusively due to surface tension and adhesion. The difficulty encountered in measuring the apparent contact angle due to mirage effects has been highlighted; a new method, fitting numerically simulated bubble profile to the contour measurements has been proposed and used to correct the effects of refraction on the bubble profile determination. As all forces acting on the bubble were measured, it was possible to estimate the residuals of the momentum balance. Their small value validated both the expressions used for the forces and the methodology to evaluate their value.

  20. Gas transfer in a bubbly wake flow

    NASA Astrophysics Data System (ADS)

    Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.

    2016-05-01

    The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.

  1. Fearless versus fearful speculative financial bubbles

    NASA Astrophysics Data System (ADS)

    Andersen, J. V.; Sornette, D.

    2004-06-01

    Using a recently introduced rational expectation model of bubbles, based on the interplay between stochasticity and positive feedbacks of prices on returns and volatility, we develop a new methodology to test how this model classifies nine time series that have been previously considered as bubbles ending in crashes. The model predicts the existence of two anomalous behaviors occurring simultaneously: (i) super-exponential price growth and (ii) volatility growth, that we refer to as the “fearful singular bubble” regime. Out of the nine time series, we find that five pass our tests and can be characterized as “fearful singular bubbles”. The four other cases are the information technology Nasdaq bubble and three bubbles of the Hang Seng index ending in crashes in 1987, 1994 and 1997. According to our analysis, these four bubbles have developed with essentially no significant increase of their volatility. This paper thus proposes that speculative bubbles ending in crashes form two groups hitherto unrecognized, namely those accompanied by increasing volatility (reflecting increasing risk perception) and those without change of volatility (reflecting an absence of risk perception).

  2. Micro-bubbles seeding for flow characterization

    NASA Astrophysics Data System (ADS)

    Aumelas, V.; Lecoffre, Y.; Maj, G.; Franc, J.-P.

    2016-11-01

    Micro-bubbles injection has long been used in hydrodynamic facilities for the control of dissolved and free air. In some cavitation tunnels [9], very large quantities of microbubbles (billions per second) are injected for rapid degassing and, in smaller quantities (millions per second), for cavitation nuclei seeding. Micro-bubbles can also be used as tracers for optical measurements including visualization, LDV or PIV. For these applications, bubbles must be sufficiently small to faithfully follow the flow. Depending on the quality and spatial characteristics of the micro-bubbles seeding, several optical methods can be applied: simple visualization gives access to semi-quantitative information on the behaviour of flows; LASER velocimetry provides information on the mean velocity and other temporal local characteristics of the flow. This paper presents some new micro-bubbles seeding devices recently developed by YLEC Consultants. These devices have been designed to fulfill specific requirements related to integration into cavitation tunnels and permit optical velocimetry measurement techniques such as Particle Image Velocimetry (PIV). The LEGI cavitation tunnel is the first tunnel which has been equipped with these microbubbles seeding systems dedicated to optical velocimetry. This paper presents the final integration schemes selected for micro-bubbles seeding into LEGI tunnel and discuss about practical concerns related to the use of the injection system for optical velocimetry.

  3. Topside sounder observations of equatorial bubbles

    NASA Technical Reports Server (NTRS)

    Dyson, P. L.; Benson, R. F.

    1978-01-01

    Large scale regions of depleted equatorial ionospheric plasma, called equatorial bubbles, are investigated using topside sounder data. The sounder's unique remote measuring capability enables the magnetic field-aligned nature of the bubbles to be investigated. A search of all available Alouette 2 and ISIS 1 ionograms during nighttime perigee passes near the magnetic equator has revealed a variety of echo signatures associated with bubbles. In addition to a sudden drop in electron density, these signatures usually include in situ spread F and ducted traces. The ducted traces have been used to determine the electron density distribution and to infer changes in ion composition along the magnetic field line within the duct associated with the bubble. In some cases it can be determined that the bubble is asymmetric with respect to the magnetic equator. Even though such features require 3 dimensional models for their explanation, the great field-aligned extent of the bubbles (relative to their cross section) suggests that current theories, which ignore variations along the magnetic field, are still applicable.

  4. Intensely oscillating cavitation bubble in microfluidics

    NASA Astrophysics Data System (ADS)

    Siew-Wan, Ohl; Tandiono; Klaseboer, Evert; Dave, Ow; Choo, Andre; Claus-Dieter, Ohl

    2015-12-01

    This study reports the technical breakthrough in generating intense ultrasonic cavitation in the confinement of a microfluidics channel [1], and applications that has been developed on this platform for the past few years [2,3,4,5]. Our system consists of circular disc transducers (10-20 mm in diameter), the microfluidics channels on PDMS (polydimethylsiloxane), and a driving circuitry. The cavitation bubbles are created at the gas- water interface due to strong capillary waves which are generated when the system is driven at its natural frequency (around 100 kHz) [1]. These bubbles oscillate and collapse within the channel. The bubbles are useful for sonochemistry and the generation of sonoluminescence [2]. When we add bacteria (Escherichia coli), and yeast cells (Pichia pastoris) into the microfluidics channels, the oscillating and collapsing bubbles stretch and lyse these cells [3]. Furthermore, the system is effective (DNA of the harvested intracellular content remains largely intact), and efficient (yield reaches saturation in less than 1 second). In another application, human red blood cells are added to a microchamber. Cell stretching and rapture are observed when a laser generated cavitation bubble expands and collapses next to the cell [4]. A numerical model of a liquid pocket surrounded by a membrane with surface tension which was placed next to an oscillating bubble was developed using the Boundary Element Method. The simulation results showed that the stretching of the liquid pocket occurs only when the surface tension is within a certain range.

  5. Psychological care in trauma patients.

    PubMed

    Mohta, Medha; Sethi, A K; Tyagi, Asha; Mohta, Anup

    2003-01-01

    The clinician manages trauma patients in the emergency room, operation theatre, intensive care unit and trauma ward with an endeavour to provide best possible treatment for physical injuries. At the same time, it is equally important to give adequate attention to behavioural and psychological aspects associated with the event. Knowledge of the predisposing factors and their management helps the clinician to prevent or manage these psychological problems. Various causes of psychological disturbances in trauma patients have been highlighted. These include pain, the sudden and unexpected nature of events and the procedures and interventions necessary to resuscitate and stabilise the patient. The ICU and trauma ward environment, sleep and sensory deprivation, impact of injury on CNS, medications and associated pre-morbid conditions are also significant factors. Specific problems that concern the traumatised patients are helplessness, humiliation, threat to body image and mental symptoms. The patients react to these stressors by various defence mechanisms like conservation withdrawal, denial, regression, anger, anxiety and depression. Some of them develop delirium or even more severe problems like acute stress disorder or post-traumatic stress disorder. Physical, pharmacological or psychological interventions can be performed to prevent or minimise these problems in trauma patients. These include adequate pain relief, prevention of sensory and sleep deprivation, providing familiar surroundings, careful explanations and reassurance to the patient, psychotherapy and pharmacological treatment whenever required.

  6. Transfusion medicine in trauma patients

    PubMed Central

    Murthi, Sarah B; Dutton, Richard P; Edelman, Bennett B; Scalea, Thomas M; Hess, John R

    2011-01-01

    Injured patients stress the transfusion service with frequent demands for uncrossmatched red cells and plasma, occasional requirements for large amounts of blood products and the need for new and better blood products. Transfusion services stress trauma centers with demands for strict accountability for individual blood component units and adherence to indications in a clinical field where research has been difficult, and guidance opinion-based. New data suggest that the most severely injured patients arrive at the trauma center already coagulopathic and that these patients benefit from prompt, specific, corrective treatment. This research is clarifying trauma system requirements for new blood products and blood-product usage patterns, but the inability to obtain informed consent from severely injured patients remains an obstacle to further research. PMID:21083009

  7. Accidental hypothermia in severe trauma.

    PubMed

    Vardon, Fanny; Mrozek, Ségolène; Geeraerts, Thomas; Fourcade, Olivier

    2016-10-01

    Hypothermia, along with acidosis and coagulopathy, is part of the lethal triad that worsen the prognosis of severe trauma patients. While accidental hypothermia is easy to identify by a simple measurement, it is no less pernicious if it is not detected or treated in the initial phase of patient care. It is a multifactorial process and is a factor of mortality in severe trauma cases. The consequences of hypothermia are many: it modifies myocardial contractions and may induce arrhythmias; it contributes to trauma-induced coagulopathy; from an immunological point of view, it diminishes inflammatory response and increases the chance of pneumonia in the patient; it inhibits the elimination of anaesthetic drugs and can complicate the calculation of dosing requirements; and it leads to an over-estimation of coagulation factor activities. This review will detail the pathophysiological consequences of hypothermia, as well as the most recent principle recommendations in dealing with it.

  8. Management of Carotid Artery Trauma

    PubMed Central

    Lee, Thomas S.; Ducic, Yadranko; Gordin, Eli; Stroman, David

    2014-01-01

    With increased awareness and liberal screening of trauma patients with identified risk factors, recent case series demonstrate improved early diagnosis of carotid artery trauma before they become problematio. There remains a need for unified screening criteria for both intracranial and extracranial carotid trauma. In the absence of contraindications, antithrombotic agents should be considered in blunt carotid artery injuries, as there is a significant risk of progression of vessel injury with observation alone. Despite CTA being used as a common screening modality, it appears to lack sufficient sensitivity. DSA remains to be the gold standard in screening. Endovascular techniques are becoming more widely accepted as the primary surgical modality in the treatment of blunt extracranial carotid injuries and penetrating/blunt intracranial carotid lessions. Nonetheless, open surgical approaches are still needed for the treatment of penetrating extracranial carotid injuries and in patients with unfavorable lesions for endovascular intervention. PMID:25136406

  9. Vascular Injury in Orthopedic Trauma.

    PubMed

    Mavrogenis, Andreas F; Panagopoulos, George N; Kokkalis, Zinon T; Koulouvaris, Panayiotis; Megaloikonomos, Panayiotis D; Igoumenou, Vasilios; Mantas, George; Moulakakis, Konstantinos G; Sfyroeras, George S; Lazaris, Andreas; Soucacos, Panayotis N

    2016-07-01

    Vascular injury in orthopedic trauma is challenging. The risk to life and limb can be high, and clinical signs initially can be subtle. Recognition and management should be a critical skill for every orthopedic surgeon. There are 5 types of vascular injury: intimal injury (flaps, disruptions, or subintimal/intramural hematomas), complete wall defects with pseudoaneurysms or hemorrhage, complete transections with hemorrhage or occlusion, arteriovenous fistulas, and spasm. Intimal defects and subintimal hematomas with possible secondary occlusion are most commonly associated with blunt trauma, whereas wall defects, complete transections, and arteriovenous fistulas usually occur with penetrating trauma. Spasm can occur after either blunt or penetrating trauma to an extremity and is more common in young patients. Clinical presentation of vascular injury may not be straightforward. Physical examination can be misleading or initially unimpressive; a normal pulse examination may be present in 5% to 15% of patients with vascular injury. Detection and treatment of vascular injuries should take place within the context of the overall resuscitation of the patient according to the established principles of the Advanced Trauma Life Support (ATLS) protocols. Advances in the field, made mostly during times of war, have made limb salvage the rule rather than the exception. Teamwork, familiarity with the often subtle signs of vascular injuries, a high index of suspicion, effective communication, appropriate use of imaging modalities, sound knowledge of relevant technique, and sequence of surgical repairs are among the essential factors that will lead to a successful outcome. This article provides a comprehensive literature review on a subject that generates significant controversy and confusion among clinicians involved in the care of trauma patients. [Orthopedics. 2016; 39(4):249-259.].

  10. Real-time on-line ultrasonic monitoring for bubbles in ceramic 'slip' in pottery pipelines.

    PubMed

    Yim, Geun Tae; Leighton, Timothy G

    2010-01-01

    When casting ceramic items in potteries, liquid 'slip' is passed from a settling tank, through overhead pipelines, before being pumped manually into the moulds. It is not uncommon for bubbles to be introduced into the slip as it passes through the complex piping network, and indeed the presence of bubbles is a major source of financial loss to the ceramics industry worldwide. This is because the bubbles almost always remain undetected until after the ceramic items have been fired in a kiln, during which process bubbles expand and create unwanted holes in the pottery. Since there it is usually an interval of several hours between the injection of the slip into the moulds, and the inspection of the items after firing, such bubble generation goes undetected on the production line during the manufacture of hundreds or even thousands of ceramic units. Not only does this mean hours of wasted staff time, power consumption and production line time: the raw material which makes up these faulty items cannot even be recycled, as fired ceramic cannot be converted back into slip. Currently, the state-of-the-art method for detecting bubbles in the opaque ceramic slip is slow and invasive, can only be used off-line, and requires expertise which is rarely available. This paper describes the invention, engineering and in-factory testing across Europe of an ultrasonic system for real-time monitoring for the presence of bubbles in casting slip. It interprets changes in the scattering statistics accompanying the presence of the bubbles, the latter being detected through perturbations in the received signal when a narrow-band ultrasonic probing wave is transmitted through the slip. The device can be bolted onto the outside of the pipeline, or used in-line. It is automated, and requires no special expertise. The acoustic problems which had to be solved were severe, and included making the system capable of monitoring the slip regardless of the material of pipe (plastic, steel, etc.) and

  11. Acoustic trauma caused by lightning.

    PubMed

    Mora-Magaña, I; Collado-Corona, M A; Toral-Martiñòn, R; Cano, A

    1996-03-01

    Lesions produced by exposure to noise are frequent in everyday life. Injuries may be found in all systems of the human body, from the digestive to the endocrine, from the cardiovascular to the nervous system. Many organs may be damaged, the ear being one of them. It is known that noise produced by factories, airports, musical instruments and even toys can cause auditory loss. Noises in nature can also cause acoustic trauma. This report is the case history of acoustic trauma caused by lightning. The patient was studied with CAT scan, electroencephalogram, and brain mapping, impedance audiometry with tympanogram and acoustic reflex, audiometry and evoked otoacoustics emissions: distortion products and transients.

  12. Male genital trauma in sports.

    PubMed

    Hunter, Stanley R; Lishnak, Timothy S; Powers, Andria M; Lisle, David K

    2013-04-01

    Male genital trauma is a rare but potentially serious sports injury. Although such an injury can occur by many different mechanisms, including falls, collisions, straddle injuries, kicks, and equipment malfunction, the clinical presentation is typically homogeneous, characterized by pain and swelling. Almost all sports-related male genital injury comes from blunt force trauma, with involvement of scrotal structures far more common than penile structures. Most injuries can be treated conservatively, but catastrophic testicular injury must first be ruled out. Despite being relatively uncommon compared with other sports injuries, more than half of all testicular injuries are sustained during sports.

  13. [Polyvagal theory and emotional trauma].

    PubMed

    Leikola, Anssi; Mäkelä, Jukka; Punkanen, Marko

    2016-01-01

    According to the polyvagal theory, the autonomic nervous system can, in deviation from the conventional theory, be divided in three distinct parts that are in hierarchical relationship with each other. The most-primitive autonomic control results in depression of vital functions, the more evolved one in fighting or escape and the most evolved one in social involvement. Practical application of the polyvagal theory has resulted in positive results above all in the treatment of emotional trauma. in Finland, therapy of complex trauma is founded on the theory of structural dissociation of the personality, which together with the polyvagal theory forms a practical frame of reference for psychotherapeutic work.

  14. Cruciform position for trauma resuscitation.

    PubMed

    Mitra, Biswadev; Fitzgerald, Mark C; Olaussen, Alexander; Thaveenthiran, Prasanthan; Bade-Boon, Jordan; Martin, Katherine; Smit, De Villiers; Cameron, Peter A

    2017-04-01

    Multiply injured patients represent a particularly demanding subgroup of trauma patients as they require urgent simultaneous clinical assessments using physical examination, ultrasound and invasive monitoring together with critical management, including tracheal intubation, thoracostomies and central venous access. Concurrent access to multiple body regions is essential to facilitate the concept of 'horizontal' resuscitation. The current positioning of trauma patient, with arms adducted, restricts this approach. Instead, the therapeutic cruciform positioning, with arms abducted at 90°, allows planning and performing of multiple life-saving interventions simultaneously. This positioning also provides a practical surgical field with improved sterility and procedural access.

  15. [Pre- and perimortem bone trauma vs. postmortem damages-- Principles of differentiation].

    PubMed

    Holz, Franziska; Birngruber, Christoph G; Verhoff, Marcel A

    2015-01-01

    In medicolegal practice, evidence of trauma or damage on human skeletons or single bones raises the question whether this was inflicted in an antemortem, perimortem, or postmortem time frame. Trauma that occurred around the time of death, i. e., perimortem trauma, is of special forensic interest, as it can yield clues about the manner and cause of death. Perimortem traumas thus need to be carefully distinguished both from antemortem injuries that were evidently survived (these can still be useful for identification purposes) and from postmortem damage, as may occur during retrieval of remains. This study offers an up-to-date review of the specialist literature, e. g. textbooks and pubmed-listed publications, identifying differentiation criteria for ante- and perimortem traumas and postmortem damage. The results that are useful for practice in actual medicolegal casework are presented, and an overview of all macroscopically visible criteria (including simple magnifications, i. e., magnifying glass) that can be used to distinguish between ante- and perimortem traumas on the one side, and postmortem damage on the other is given. The difficulty of distinguishing antemortem trauma and postmortem damage from perimortem trauma rises sharply the closer in time they were inflicted to the time of the death event. Additional postmortem changes due to exposure of the bones to the surrounding deposition conditions may also occur after the relevant postmortem damage or antemortem trauma was inflicted and further complicate the problem. In this context, the "perimortem interval" and the "Fracture Freshness Index" (FFI) are discussed as means to classify the time frame of traumas.

  16. Towards numerical simulation of bubbly flows in complex geometries

    NASA Astrophysics Data System (ADS)

    Mattson, Michael; Mahesh, Krishnan

    2008-11-01

    We are developing the LES capability for bubbly flows in complex geometries using unstructured grids and an Euler--Lagrangian methodology. Two Lagrangian bubble models are considered: (i) the bubbles are treated as a dispersed phase in the carrier fluid, and individual bubbles are point particles governed by an equation for bubble motion and (ii) the force coupling method by Maxey et al. [Fluid Dyn. Res., 32 (1997), 143-156]. The evolution of the bubble radius (assuming spherical bubbles) is governed by the Rayleigh--Plesset equation and integrated using a Runge--Kutta integrator with adaptive time-stepping. The talk will discuss numerical issues and contrast results between the two methodologies. Numerical results ranging from the motion of individual bubbles in channels and around bodies to drag reduction by bubbles in turbulent channel flow will be presented.

  17. Facial nerve palsy due to birth trauma

    MedlinePlus

    Seventh cranial nerve palsy due to birth trauma; Facial palsy - birth trauma; Facial palsy - neonate; Facial palsy - infant ... infant's facial nerve is also called the seventh cranial nerve. It can be damaged just before or at ...

  18. Financial Bubbles, Real Estate Bubbles, Derivative Bubbles, and the Financial and Economic Crisis

    NASA Astrophysics Data System (ADS)

    Sornette, Didier; Woodard, Ryan

    The financial crisis of 2008, which started with an initially well-defined epicenter focused on mortgage backed securities (MBS), has been cascading into a global economic recession, whose increasing severity and uncertain duration has led and is continuing to lead to massive losses and damage for billions of people. Heavy central bank interventions and government spending programs have been launched worldwide and especially in the USA and Europe, with the hope to unfreeze credit and bolster consumption. Here, we present evidence and articulate a general framework that allows one to diagnose the fundamental cause of the unfolding financial and economic crisis: the accumulation of several bubbles and their interplay and mutual reinforcement have led to an illusion of a "perpetual money machine" allowing financial institutions to extract wealth from an unsustainable artificial process. Taking stock of this diagnostic, we conclude that many of the interventions to address the so-called liquidity crisis and to encourage more consumption are ill-advised and even dangerous, given that precautionary reserves were not accumulated in the "good times" but that huge liabilities were. The most "interesting" present times constitute unique opportunities but also great challenges, for which we offer a few recommendations.

  19. Validation of Bubble Dynamics Equation for a Nano-scale Bubble via Molecular Dynamics Simulation

    NASA Astrophysics Data System (ADS)

    Tsuda, S.; Hyodo, H.; Watanabe, S.

    2015-12-01

    For a validation of the application of conventional bubble dynamics to a nano-scale bubble behaviour, we simulated a nano-scale bubble collapsing or vibration by Molecular Dynamics (MD) method and compared the result with the solution of Rayleigh-Plesset (RP) equation and that of Confined RP (CRP) equation, whose boundary condition was corrected to be consistent with that of MD simulation. As a result, a good coincidence was obtained between MD, RP, and CRP in the case of one-component fluid. In addition, also a good correspondence was obtained particularly in the comparison between MD and CRP in the case of two-component fluid containing non-condensable gas. The present results indicate that conventional bubble dynamics equation can be applied even to a nano-scale tiny bubble.

  20. Perception of differences between trauma care and other surgical emergencies: results from a national survey of surgeons.

    PubMed

    Esposito, T J; Kuby, A M; Unfred, C; Young, H L; Gamelli, R L

    1994-12-01

    A national sample of 2500 surgeons was surveyed. Thirteen variables were analyzed to ascertain perceived differences between trauma care and other surgical emergencies, as well as to identify factors contributing to a preferential reluctance to treat trauma. The response rate was 60%. Trauma was perceived as most likely to occur at inconvenient times by 67% of respondents, more often complex (44%), and more demanding of specialized knowledge (39%). Trauma was viewed as less likely to be reimbursed by 35% and most often litigious by 30%. Fewer respondents perceived differences for risk of exposure to lethal pathogens and violence (26% and 9%) and personal or professional rewards (25%). Surgeons who prefer to treat trauma view it as more often demanding of specialized knowledge and more complex than other surgical emergencies. Surgeons who prefer not to treat trauma or take trauma call perceive it as never personally or professionally rewarding, more often disruptive to personal life, emotionally taxing, litigious, and inconvenient compared with other emergencies. Perception of dissimilar reimbursement and personal health risk are less often associated factors. Perceived differences in the litigious nature of cases are not based on fact. We conclude that the individual degree of reluctance or enthusiasm for trauma care in comparison with other emergencies is influenced by perception, personality, and myth rather than by logic and facts.

  1. Particle-bubble aggregate stability on static bubble generated by single nozzle on flotation process

    NASA Astrophysics Data System (ADS)

    Warjito, Harinaldi, Setyantono, Manus; Siregar, Sahala D.

    2016-06-01

    There are three sub-processes on flotation. These processes are intervening liquid film into critical thickness, rupture of liquid film forming three phase contact line, and expansion three phase contact line forming aggregate stability. Aggregate stability factor contribute to determine flotation efficiency. Aggregate stability has some important factors such as reagent and particle geometry. This research focussed on to understand effect of particle geometry to aggregate stability. Experimental setup consists of 9 x 9 x26 cm flotation column made of glass, bubble generator, particle feeding system, and high speed video camera. Bubble generator made from single nozzle with 0.3 mm diameter attached to programmable syringe pump. Particle feeding system made of pipette. Particle used in this research is taken from open pit Grasberg in Timika, Papua. Particle has sub-angular geometry and its size varies from 38 to 300 µm. Bubble-particle interaction are recorded using high speed video camera. Recordings from high speed video camera analyzed using image processing software. Experiment result shows that aggregate particle-bubble and induction time depends on particle size. Small particle (38-106 µm) has long induction time and able to rupture liquid film and also forming three phase contact line. Big particle (150-300 µm) has short induction time, so it unable to attach with bubble easily. This phenomenon is caused by apparent gravity work on particle-bubble interaction. Apparent gravity worked during particle sliding on bubble surface experience increase and reached its maximum magnitude at bubble equator. After particle passed bubble equator, apparent gravity force experience decrease. In conclusion particle size from 38-300 µm can form stable aggregate if particle attached with bubble in certain condition.

  2. Cultural Differences in Autobiographical Memory of Trauma

    ERIC Educational Resources Information Center

    Jobson, Laura; O'Kearney, Richard

    2006-01-01

    This study investigated cultural differences in autobiographical memory of trauma. Australian and Asian international students provided self-defining memories, narratives of everyday and trauma memories and self-reports assessing adjustment to the trauma. No cultural distinction was found in how Australian or Asian subjects remembered a personal…

  3. Pneumomediastinum, an unusual complication of facial trauma.

    PubMed

    Monksfield, Peter; Whiteside, Olivia; Jaffé, Susan; Steventon, Nick; Milford, Chris

    2005-05-01

    Pneumomediastinum is often an incidental finding following a blunt or penetrating trauma to the neck or chest. We report a rare case of pneumomediastinum following an isolated facial trauma that was diagnosed on imaging. We also review the clinical signs of this condition, its radiologic characteristics, and the 18 previously reported cases of pneumomediastinum following facial trauma.

  4. Addressing Trauma in Substance Abuse Treatment

    ERIC Educational Resources Information Center

    Giordano, Amanda L.; Prosek, Elizabeth A.; Stamman, Julia; Callahan, Molly M.; Loseu, Sahar; Bevly, Cynthia M.; Cross, Kaitlin; Woehler, Elliott S.; Calzada, Richard-Michael R.; Chadwell, Katie

    2016-01-01

    Trauma is prevalent among clients with substance abuse issues, yet addictions counselors' training in trauma approaches is limited. The purpose of the current article is to provide pertinent information regarding trauma treatment including the use of assessments, empirically supported clinical approaches, self-help groups and the risk of vicarious…

  5. Bladder trauma: multidetector computed tomography cystography.

    PubMed

    Ishak, Charbel; Kanth, Nalini

    2011-08-01

    Multidetector computed tomography (MDCT) cystography is rapidly becoming the most recommended study for evaluation of the bladder for suspected trauma. This article reviews the bladder trauma with emphasis on the application of MDCT cystography to traumatic bladder injuries using a pictorial essay based on images collected in our level I trauma center.

  6. Helpers in Distress: Preventing Secondary Trauma

    ERIC Educational Resources Information Center

    Whitfield, Natasha; Kanter, Deborah

    2014-01-01

    Those in close contact with trauma survivors are themselves at risk for trauma (e.g., Bride, 2007; Figley, 1995). Family, friends, and professionals who bear witness to the emotional retelling and re-enacting of traumatic events can experience what is called "secondary trauma" (Elwood, Mott, Lohr, & Galovski, 2011). The literature…

  7. Numerical Study of Underwater Explosions and Following Bubble Pulses

    NASA Astrophysics Data System (ADS)

    Abe, A.; Katayama, M.; Murata, K.; Kato, Y.; Tanaka, K.

    2007-12-01

    Underwater explosions and following bubble pulses were simulated by using a hydrocode ANSYS® AUTODYN®. Effects of (a) pressure gradient depending on a water depth, (b) atmospheric pressure, (c) gravitational acceleration during bubble pulsation and (d) reaction process of non-ideal detonation on bubble pulsation phenomena were investigated numerically. Numerical bubble properties were compared with experimental data. Emulsion explosive of a charge weight 100 g was detonated at water depth of 4 m in an underwater explosion testing tank. These conditions (a), (b) and (d) could lead precise simulations of the bubble pulses consistent with the experimental data. The condition (c) could give bubble upward motion under its buoyancy effect.

  8. Self-structured, current aperture approach for bubble memory

    NASA Technical Reports Server (NTRS)

    Nelson, G. L.; Krahn, D. R.; Dean, R. H.; Paul, M. C.; Tolman, C. H.

    1985-01-01

    An approach to magnetic bubble memory which incorporates dual conductor current access drive with a self-structured (strongly interacting) bubble lattice is described. This is expected to provide higher operating speeds, defect tolerance, and higher bit density for a given bubble size as compared to present field access bubble devices. Bubble spacings of 2.5 bubble diameters are projected for a prototype device. Experimental work on device components including detectors, major/minor loops, and gates is described. Defect tolerance has also been demonstrated.

  9. Tribology of thin wetting films between bubble and moving solid surface.

    PubMed

    Karakashev, Stoyan I; Stöckelhuber, Klaus W; Tsekov, Roumen; Phan, Chi M; Heinrich, Gert

    2014-08-01

    This work shows a successful example of coupling of theory and experiment to study the tribology of bubble rubbing on solid surface. Such kind of investigation is reported for the first time in the literature. A theory about wetting film intercalated between bubble and moving solid surface was developed, thus deriving the non-linear evolution differential equation which accounted for the friction slip coefficient at the solid surface. The stationary 3D film thickness profile, which appears to be a solution of the differential equation, for each particular speed of motion of the solid surface was derived by means of special procedure and unique interferometric experimental setup. This allowed us to determine the 3D map of the lift pressure within the wetting film, the friction force per unit area and the friction coefficient of rubbing at different speeds of motion of the solid surface. Thus, we observed interesting tribological details about the rubbing of the bubble on the solid surface like for example: 1. A regime of mixed friction between dry and lubricated friction exists in the range of 6-170 μm/s, beyond which the rubbing between the bubble and solid becomes completely lubricated and passes through the maximum; 2. The friction coefficient of rubbing has high values at very small speeds of solid's motion and reduces substantially with the increase of the speed of the solid motion until reaching small values, which change insignificantly with the further increase of the speed of the solid. Despite the numerous studies on the motion of bubble/droplet in close proximity to solid wall in the literature, the present investigation appears to be a step ahead in this area as far as we were able to derive 3D maps of the bubble close to the solid surface, which makes the investigation more profound.

  10. Herds of methane chambers grazing bubbles

    NASA Astrophysics Data System (ADS)

    Grinham, Alistair; Dunbabin, Matthew

    2014-05-01

    Water to air methane emissions from freshwater reservoirs can be dominated by sediment bubbling (ebullitive) events. Previous work to quantify methane bubbling from a number of Australian sub-tropical reservoirs has shown that this can contribute as much as 95% of total emissions. These bubbling events are controlled by a variety of different factors including water depth, surface and internal waves, wind seiching, atmospheric pressure changes and water levels changes. Key to quantifying the magnitude of this emission pathway is estimating both the bubbling rate as well as the areal extent of bubbling. Both bubbling rate and areal extent are seldom constant and require persistent monitoring over extended time periods before true estimates can be generated. In this paper we present a novel system for persistent monitoring of both bubbling rate and areal extent using multiple robotic surface chambers and adaptive sampling (grazing) algorithms to automate the quantification process. Individual chambers are self-propelled and guided and communicate between each other without the need for supervised control. They can maintain station at a sampling site for a desired incubation period and continuously monitor, record and report fluxes during the incubation. To exploit the methane sensor detection capabilities, the chamber can be automatically lowered to decrease the head-space and increase concentration. The grazing algorithms assign a hierarchical order to chambers within a preselected zone. Chambers then converge on the individual recording the highest 15 minute bubbling rate. Individuals maintain a specified distance apart from each other during each sampling period before all individuals are then required to move to different locations based on a sampling algorithm (systematic or adaptive) exploiting prior measurements. This system has been field tested on a large-scale subtropical reservoir, Little Nerang Dam, and over monthly timescales. Using this technique

  11. Bubble transport in subcooled flow boiling

    NASA Astrophysics Data System (ADS)

    Owoeye, Eyitayo James

    Understanding the behavior of bubbles in subcooled flow boiling is important for optimum design and safety in several industrial applications. Bubble dynamics involve a complex combination of multiphase flow, heat transfer, and turbulence. When a vapor bubble is nucleated on a vertical heated wall, it typically slides and grows along the wall until it detaches into the bulk liquid. The bubble transfers heat from the wall into the subcooled liquid during this process. Effective control of this transport phenomenon is important for nuclear reactor cooling and requires the study of interfacial heat and mass transfer in a turbulent flow. Three approaches are commonly used in computational analysis of two-phase flow: Eulerian-Lagrangian, Eulerian-Eulerian, and interface tracking methods. The Eulerian- Lagrangian model assumes a spherical non-deformable bubble in a homogeneous domain. The Eulerian-Eulerian model solves separate conservation equations for each phase using averaging and closure laws. The interface tracking method solves a single set of conservation equations with the interfacial properties computed from the properties of both phases. It is less computationally expensive and does not require empirical relations at the fluid interface. Among the most established interface tracking techniques is the volume-of-fluid (VOF) method. VOF is accurate, conserves mass, captures topology changes, and permits sharp interfaces. This work involves the behavior of vapor bubbles in upward subcooled flow boiling. Both laminar and turbulent flow conditions are considered with corresponding pipe Reynolds number of 0 -- 410,000 using a large eddy simulation (LES) turbulence model and VOF interface tracking method. The study was performed at operating conditions that cover those of boiling water reactors (BWR) and pressurized water reactors (PWR). The analysis focused on the life cycle of vapor bubble after departing from its nucleation site, i.e. growth, slide, lift-off, rise

  12. The management of liver trauma.

    PubMed Central

    Macfarlane, R.

    1985-01-01

    Despite advances in the management of liver trauma during the past 40 years, haemorrhage has remained the commonest cause of death. This article outlines the diversity of opinion between the desire to determine the extent of damage and resect devitalised tissue with its attendant risk of exacerbating haemorrhage, and the alternative of a more conservative approach. PMID:3895205

  13. Transforming Cultural Trauma into Resilience

    ERIC Educational Resources Information Center

    Brokenleg, Martin

    2012-01-01

    One of the biggest challenges facing Aboriginal populations increasingly is being called "intergenerational trauma." Restoring the cultural heritage is a central theme in the book, "Reclaiming Youth at Risk." That work describes the Circle of Courage model for positive development which blends Native child and youth care…

  14. The Trauma-Sensitive Teacher

    ERIC Educational Resources Information Center

    Craig, Susan E.

    2016-01-01

    According to the National Center for Mental Health Promotion and Youth Violence Prevention, about one quarter of children in the United States will witness or experience a traumatic event before the age of four. In this article, Susan E. Craig explains how these early trauma histories prime a child's brain to expect certain experiences,…

  15. Neuropathology of Acquired Cerebral Trauma.

    ERIC Educational Resources Information Center

    Bigler, Erin D.

    1987-01-01

    To help educators understand the cognitive and behavioral sequelae of cerebral injury, the neuropathology of traumatic brain injury and the main neuropathological features resulting from trauma-related brain damage are reviewed. A glossary with definitions of 37 neurological terms is appended. (Author/DB)

  16. Medicating Relational Trauma in Youth

    ERIC Educational Resources Information Center

    Foltz, Robert

    2008-01-01

    Children who have experienced relational trauma present a host of problems and are often diagnosed with psychiatric disorders and then medicated. But there is evidence that commonly used drugs interfere with oxytocin or vasopressin, the human trust and bonding hormones. Thus, psychotropic drugs may impair interpersonal relationships and impede…

  17. The morbidity of trauma nephrectomy.

    PubMed

    Edwards, Norma M; Claridge, Jeffrey A; Forsythe, Raquel M; Weinberg, Jordan A; Croce, Martin A; Fabian, Timothy C

    2009-11-01

    Mortality has been shown to be high in patients after trauma nephrectomy (TN). However, there are little data regarding morbidity in survivors. The objective of this study was to determine the morbidity rates associated with TN with attention directed to renal failure (RF) and formation of intra-abdominal abscess (IAA). Patients who underwent TN over a 9-year period (1996 to 2004) were identified from the trauma registry. Records were reviewed for all complications after TN in patients surviving at least 48 hours. Eighty-nine patients were identified with TN; 61 per cent resulted after penetrating trauma. Overall mortality was 34 per cent. Seventy-one patients survived greater than 48 hours; 51 (72%) experienced at least one morbidity. There was no difference in morbidity rates between patients undergoing blunt trauma and those undergoing penetrating trama. Patients with morbidities were significantly older, more severely injured, and had higher mortality rates and longer hospital courses. Infectious complications were seen in 52 per cent, respiratory in 48 per cent, gastrointestinal in 30 per cent, coagulopathy in 25 per cent, and RF and IAA were each seen in 14 per cent of patients. Patients undergoing TN are severely injured with significant morbidity. The results from this study allow us to establish benchmarks to assess complication rates for patients who undergo TN, which can provide prognostic information and goals to improve patient outcomes.

  18. Hypothermia and the trauma patient

    PubMed Central

    Kirkpatrick, Andrew W.; Chun, Rosaleen; Brown, Ross; Simons, Richard K.

    Hypothermia has profound effects on every system in the body, causing an overall slowing of enzymatic reactions and reduced metabolic requirements. Hypothermic, acutely injured patients with multisystem trauma have adverse outcomes when compared with normothermic control patients. Trauma patients are inherently predisposed to hypothermia from a variety of intrinsic and iatrogenic causes. Coagulation and cardiac sequelae are the most pertinent physiological concerns. Hypothermia and coagulopathy often mandate a simplified approach to complex surgical problems. A modification of traditional classification systems of hypothermia, applicable to trauma patients is suggested. There are few controlled investigations, but clinical opinion strongly supports the active prevention of hypothermia in the acutely traumatized patient. Preventive measures are simple and inexpensive, but the active reversal of hypothermia is much more complicated, often invasive and controversial. The ideal method of rewarming is unclear but must be individualized to the patient and is institution specific. An algorithm reflecting newer approaches to traumatic injury and technical advances in equipment and techniques is suggested. Conversely, hypothermia has selected clinical benefits when appropriately used in cases of trauma. Severe hypothermia has allowed remarkable survivals in the course of accidental circulatory arrest. The selective application of mild hypothermia in severe traumatic brain injury is an area with promise. Deliberate circulatory arrest with hypothermic cerebral protection has also been used for seemingly unrepairable injuries and is the focus of ongoing research. PMID:10526517

  19. Detecting dark matter with scintillating bubble chambers

    NASA Astrophysics Data System (ADS)

    Zhang, Jianjie; Dahl, C. Eric; Jin, Miaotianzi; Baxter, Daniel

    2016-03-01

    Threshold based direct WIMP dark matter detectors such as the superheated bubble chambers developed by the PICO experiment have demonstrated excellent electron-recoil and alpha discrimination, excellent scalability, ease of change of target fluid, and low cost. However, the nuclear-recoil like backgrounds have been a limiting factor in their dark matter sensitivity. We present a new type of detector, the scintillating bubble chamber, which reads out the scintillation pulse of the scattering events as well as the pressure, temperature, acoustic traces, and bubble images as a conventional bubble chamber does. The event energy provides additional handle to discriminate against the nuclear-recoil like backgrounds. Liquid xenon is chosen as the target fluid in our prototyping detector for its high scintillation yield and suitable vapor pressure which simplifies detector complexity. The detector can be used as an R&D tool to study the backgrounds present in the current PICO bubble chambers or as a prototype for standalone dark matter detectors in the future. Supported by DOE Grant DE-SC0012161.

  20. The life of bubbles under negative pressure

    NASA Astrophysics Data System (ADS)

    Choi, Jin Woo; Park, Keunhwan; Nagashima, So; Moon, Myoung-Woon; Kim, Ho-Young

    2016-11-01

    Cavitation of sap in plant vessels, or embolism, may occur when the liquid pressure becomes negative either in a high elevation or a dry environment. Effective suppression of nucleation and growth of cavitation bubbles is important for continuous transport of water and thus survival of the plant. Here we investigate the life of cavitation bubbles under negative pressure from their nucleation through growth and maturation. As a model system for the plant vessel, we fabricate hydrogel microchannels whose inner pressure is reduced to a negative value. The roughness of the channel surface is modified by plasma treatment to form wrinkles emulating observed xylem wall surfaces. We find a finite effect of surface wrinkles on the critical nucleation pressure. Also, dense wrinkles tend to slow down bubble growth. In all the channel roughness conditions, the bubbles grow diffusively with time until their maturation. Then in the matured stage, the growth speed is substantially lowered and follows the value determined by Darcy's law. Our results suggest that surface wrinkles or roughness can be used to control the nucleation pressure and bubble growth behavior. Also, the observations can give deeper insight into embolism control mechanisms of tall trees.

  1. Optical absorption properties of electron bubbles and experiments on monitoring individual electron bubbles in liquid helium

    NASA Astrophysics Data System (ADS)

    Guo, Wei

    When a free electron is injected into liquid helium, it forms a microscopic bubble essentially free of helium atoms, which is referred to as an electron bubble. It represents a fine example of a quantum-mechanical particle confined in a potential well. In this dissertation, we describe our studies on bubble properties, especially the optical absorption properties of ground state electron bubbles and experiments on imaging individual electron bubbles in liquid helium. We studied the effect of zero-point and thermal fluctuations on the shape of ground state electron bubbles in liquid helium. The results are used to determine the line shape for the 1S to 1P optical transition. The calculated line shape is in very good agreement with the experimental measurements of Grimes and Adams. For 1S to 2P transition, the obtained transition line width agrees well with the measured data of Zipfel over a range of pressure up to 15 bars. Fluctuations in the bubble shape also make other "unallowed" transitions possible. The transition cross-sections from the 1S state to the 1D and 2D states are calculated with magnitude approximately two orders smaller than that of the 1S to 1P and 2P transitions. In our electron bubble imaging experiments, a planar ultrasonic transducer was used to generate strong sound wave pulse in liquid helium. The sound pulse passed through the liquid so as to produce a transient negative pressure over a large volume (˜ 1 cm3). An electron bubble that was passed by the sound pulse exploded for a fraction of a microsecond and grew to have a radius of around 10 microns. While the bubble had this large size it was illuminated with a flash lamp and its position was recorded. In this way, we can determine its position. Through the application of a series of sound pulses, we can then take images along the track of individual electrons. The motion of individual electron bubbles has been successfully monitored. Interesting bubble tracks that may relate to electrons

  2. Near-wall measurements of the bubble- and Lorentz-force-driven convection at gas-evolving electrodes

    NASA Astrophysics Data System (ADS)

    Baczyzmalski, Dominik; Weier, Tom; Kähler, Christian J.; Cierpka, Christian

    2015-08-01

    Chemical energy storage systems, e.g., in the form of hydrogen or methanol, have a great potential for the establishment of volatile renewable energy sources due to the large energy density. The efficiency of hydrogen production through water electrolysis is, however, limited by gas bubbles evolving at the electrode's surface and can be enhanced by an accelerated bubble detachment. In order to characterize the complex multi-phase flow near the electrode, simultaneous measurements of the fluid velocities and the size and trajectories of hydrogen bubbles were performed in a water electrolyzer. The liquid phase velocity was measured by PIV/PTV, while shadowgraphy was used to determine the bubble trajectories. Special measurement and evaluation techniques had to be applied as the measurement uncertainty is strongly affected by the high void fraction close to the wall. In particular, the application of an advanced PTV scheme allowed for more precise fluid velocity measurements closer to electrode. Based on these data, stability characteristics of the near-wall flow were evaluated and compared to that of a wall jet. PTV was used as well to investigate the effect of Lorentz forces on the near-wall fluid velocities. The results show a significantly increased wall parallel liquid phase velocity with increasing Lorentz forces. It is presumed that this enhances the detachment of hydrogen bubbles from the electrode surface and, consequently, decreases the fractional bubble coverage and improves the efficiency. In addition, the effect of large rising bubbles with path oscillations on the near-wall flow was investigated. These bubbles can have a strong impact on the mass transfer near the electrode and thus affect the performance of the process.

  3. Numerical and physical modelling of bubbly flow phenomena

    SciTech Connect

    Sangani, A.S.

    1992-02-01

    The objective of the proposed research is to develop a theoretical framework for analyzing various two-phase flows, with special emphasis on the flows, with special emphasis on the flows of gas- liquid dispersions. The macroscopic behavior of these flows depends on the details of the microstructure of the dispersion, and these details, in turn, depend on the nature of the flow. Given the very diverse nature of the flows and their complex dependence on the microstructure of the dispersion, it is unlikely that a single set of equations, similar to the Navier-Stokes equations for homogeneous fluids, will apply to all the different situations. What is possible, however, is to develop general methodologies that can be used to examine specific situations and a general understanding about different kinds of macroscopic flows. The aim of the proposed research is to develop efficient numerical techniques for carrying out dynamic simulations of flows of dispersions and to apply them to a carefully selected problems whose solutions would reveal important qualitative as well as quantitative insights into the complex interdependence of the microstructure and macroscopic properties of the flows. These numerical techniques are to be supplemented with the techniques of ensemble averaging and statistical physics to obtain results that could be used in modelling more complicated flows through a set of relatively simple equations. Two classes of macroscopic flows were analyzed in detail during the current funding period. The first is the oscillatory flows, as in the case of acoustic or pressure wave propagation through bubbly liquids, and the second is convective flows as in bubbles rising through a liquid. 20 refs.

  4. Numerical and physical modelling of bubbly flow phenomena. Progress report

    SciTech Connect

    Sangani, A.S.

    1992-02-01

    The objective of the proposed research is to develop a theoretical framework for analyzing various two-phase flows, with special emphasis on the flows, with special emphasis on the flows of gas- liquid dispersions. The macroscopic behavior of these flows depends on the details of the microstructure of the dispersion, and these details, in turn, depend on the nature of the flow. Given the very diverse nature of the flows and their complex dependence on the microstructure of the dispersion, it is unlikely that a single set of equations, similar to the Navier-Stokes equations for homogeneous fluids, will apply to all the different situations. What is possible, however, is to develop general methodologies that can be used to examine specific situations and a general understanding about different kinds of macroscopic flows. The aim of the proposed research is to develop efficient numerical techniques for carrying out dynamic simulations of flows of dispersions and to apply them to a carefully selected problems whose solutions would reveal important qualitative as well as quantitative insights into the complex interdependence of the microstructure and macroscopic properties of the flows. These numerical techniques are to be supplemented with the techniques of ensemble averaging and statistical physics to obtain results that could be used in modelling more complicated flows through a set of relatively simple equations. Two classes of macroscopic flows were analyzed in detail during the current funding period. The first is the oscillatory flows, as in the case of acoustic or pressure wave propagation through bubbly liquids, and the second is convective flows as in bubbles rising through a liquid. 20 refs.

  5. Nonpathologizing trauma interventions in abnormal psychology courses.

    PubMed

    Hoover, Stephanie M; Luchner, Andrew F; Pickett, Rachel F

    2016-01-01

    Because abnormal psychology courses presuppose a focus on pathological human functioning, nonpathologizing interventions within these classes are particularly powerful and can reach survivors, bystanders, and perpetrators. Interventions are needed to improve the social response to trauma on college campuses. By applying psychodynamic and feminist multicultural theory, instructors can deliver nonpathologizing interventions about trauma and trauma response within these classes. We recommend class-based interventions with the following aims: (a) intentionally using nonpathologizing language, (b) normalizing trauma responses, (c) subjectively defining trauma, (d) challenging secondary victimization, and (e) questioning the delineation of abnormal and normal. The recommendations promote implications for instructor self-reflection, therapy interventions, and future research.

  6. The family of the trauma victim.

    PubMed

    Solursh, D S

    1990-03-01

    Emergency room and trauma unit work offers unique challenges to the nurse, both professionally and personally. One of these challenges is understanding and dealing with the behavior of victims' families. Some of the factors that impact on the behavior of families include (1) the sudden and unpredictable nature of trauma; (2) the nature of the relationship of the specific family member and the trauma victim; (3) the issues of responsibility, anger, and guilt; (4) religious beliefs; and (5) trauma sequelae. The development of organ and tissue donor programs and of psychotraumatology as ways to help ease the plight of trauma victims' families are also discussed.

  7. Temperature Nonequilibration during Single-Bubble Sonoluminescence.

    PubMed

    Flannigan, David J; Suslick, Kenneth S

    2012-09-06

    Single-bubble sonoluminescence (SBSL) spectra from liquids having low vapor pressures, especially mineral acids, are exceptionally rich. During SBSL from aqueous sulfuric acid containing dissolved neon, rovibronic emission spectra reveal vibrationally hot sulfur monoxide (SO; Tv = 2100 K) that is also rotationally cold (Tr = 290 K). In addition to SO, excited neon atom emission gives an estimated temperature, for neon, of several thousand Kelvin. This nonequilibrated temperature is consistent with dynamically constrained SO formation at the liquid-vapor interface of the collapsing bubble. Formation occurs via collisions of fast neon atoms (generated within the collapsing bubble) with liquid-phase molecular species in the interfacial region, thus allowing for a mechanistic understanding of the processes leading to light emission.

  8. Bubble and Drop Nonlinear Dynamics experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Bubble and Drop Nonlinear Dynamics (BDND) experiment was designed to improve understanding of how the shape and behavior of bubbles respond to ultrasound pressure. By understanding this behavior, it may be possible to counteract complications bubbles cause during materials processing on the ground. This 12-second sequence came from video downlinked from STS-94, July 5 1997, MET:3/19:15 (approximate). The BDND guest investigator was Gary Leal of the University of California, Santa Barbara. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced fluid dynamics experiments will be a part of investigations plarned for the International Space Station. (189KB JPEG, 1293 x 1460 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300163.html.

  9. Analysis of airfoil transitional separation bubbles

    NASA Technical Reports Server (NTRS)

    Davis, R. L.; Carter, J. E.

    1984-01-01

    A previously developed local inviscid-viscous interaction technique for the analysis of airfoil transitional separation bubbles, ALESEP (Airfoil Leading Edge Separation) has been modified to utilize a more accurate windward finite difference procedure in the reversed flow region, and a natural transition/turbulence model has been incorporated for the prediction of transition within the separation bubble. Numerous calculations and experimental comparisons are presented to demonstrate the effects of the windward differencing scheme and the natural transition/turbulence model. Grid sensitivity and convergence capabilities of this inviscid-viscous interaction technique are briefly addressed. A major contribution of this report is that with the use of windward differencing, a second, counter-rotating eddy has been found to exist in the wall layer of the primary separation bubble.

  10. Bubbles, shocks and elementary technical trading strategies

    NASA Astrophysics Data System (ADS)

    Fry, John

    2014-01-01

    In this paper we provide a unifying framework for a set of seemingly disparate models for bubbles, shocks and elementary technical trading strategies in financial markets. Markets operate by balancing intrinsic levels of risk and return. This seemingly simple observation is commonly over-looked by academics and practitioners alike. Our model shares its origins in statistical physics with others. However, under our approach, changes in market regime can be explicitly shown to represent a phase transition from random to deterministic behaviour in prices. This structure leads to an improved physical and econometric model. We develop models for bubbles, shocks and elementary technical trading strategies. The list of empirical applications is both interesting and topical and includes real-estate bubbles and the on-going Eurozone crisis. We close by comparing the results of our model with purely qualitative findings from the finance literature.

  11. Acoustic Scattering from Compact Bubble Clouds.

    NASA Astrophysics Data System (ADS)

    Schindall, Jeffrey Alan

    In this study, a simple model describing the low -frequency scattering properties of high void fraction bubble clouds in both the free field and near the ocean surface is developed. This model, which is based on an effective medium approximation and acoustically compact scatters, successfully predicts the results of the bubble cloud scattering experiment carried out at Lake Seneca in New York state for frequencies consistent with the model assumptions (Roy et al., 1992). The introduction of the surface is facilitated by the method of images and is subject to the same constraint of low-acoustic frequency imposed by the compact scatterer assumption. This model is not intended to serve as an exact replicate of oceanic bubble cloud scattering. The model herein was kept simple by design, for only then can the complex physical behavior be expressed in a simple analytical form. Simple, analytic theories facilitate the exploration of parameter space, and more importantly serve to illuminate the underlying physics.

  12. High Energy Neutrinos from the Fermi Bubbles

    SciTech Connect

    Lunardini, Cecilia; Razzaque, Soebur

    2012-06-01

    Recently the Fermi-LAT data have revealed two gamma-ray emitting bubble-shaped structures at the Galactic center. If the observed gamma rays have hadronic origin (collisions of accelerated protons), the bubbles must emit high energy neutrinos as well. This new, Galactic, neutrino flux should trace the gamma-ray emission in spectrum and spatial extent. Its highest energy part, above 20–50 TeV, is observable at a kilometer-scale detector in the northern hemisphere, such as the planned KM3NeT, while interesting constraints on it could be obtained by the IceCube Neutrino Observatory at the South Pole. The detection or exclusion of neutrinos from the Fermi bubbles will discriminate between hadronic and leptonic models, thus bringing unique information on the still mysterious origin of these objects and on the time scale of their formation.

  13. High energy neutrinos from the Fermi bubbles.

    PubMed

    Lunardini, Cecilia; Razzaque, Soebur

    2012-06-01

    Recently the Fermi-LAT data have revealed two gamma-ray emitting bubble-shaped structures at the Galactic center. If the observed gamma rays have hadronic origin (collisions of accelerated protons), the bubbles must emit high energy neutrinos as well. This new, Galactic, neutrino flux should trace the gamma-ray emission in spectrum and spatial extent. Its highest energy part, above 20-50 TeV, is observable at a kilometer-scale detector in the northern hemisphere, such as the planned KM3NeT, while interesting constraints on it could be obtained by the IceCube Neutrino Observatory at the South Pole. The detection or exclusion of neutrinos from the Fermi bubbles will discriminate between hadronic and leptonic models, thus bringing unique information on the still mysterious origin of these objects and on the time scale of their formation.

  14. Root Causes of the Housing Bubble

    NASA Astrophysics Data System (ADS)

    Kaizoji, Taisei

    In this chapter we investigate root causes of the recent US housing bubble which has been caused a serious downturn in US economic growth since autumn of 2008. We propose a simple model of housing markets in order to indicate the possible determinants of recent housing prices. Utilizing the model, we verify a number of hypotheses which have been proposed in the recent literature on the housing bubbles. We suggest that the main causes of the housing bubble from 2000 to 2006 are (1) non-elastic housing supply in the metropolitan areas, and (2) declines in the mortgage loan rate and the housing premium by the massive mortgage credit expansion. We also suggest that these factors were strongly influenced by policies that governments and the Federal Reserve Board performed.

  15. Refraction by a spherical nematic bubble

    NASA Astrophysics Data System (ADS)

    Sherman, Richard David

    1989-08-01

    A formalism is developed to study refraction by a spherical nematic bubble. It is applicable to bubbles that are larger than light wavelengths, but smaller than the dimensions for excitation of director-fluctuation-induced scattering. The technique yields a nonlinear differential equation and an associated integral which govern the trajectory of a ray inside a nematic region for an arbitrary director configuration. Explicit solutions are provided for five simple interior arrangements-isotropic, onion skin, radial star, horizontal (bottle brush), and vertical. It is then demonstrated that for extraordinary-ordinary refractive-index difference small compared to either, interfacial refraction at the bubble surface is the dominant contribution; deviations from a rectilinear path are small. When ranked in terms of decreasing scattering effectiveness, the sequence is horizontal, onion, isotropic, radial, and vertical if the light is linearly polarized and coupling optimally to the extraordinary index component; for unpolarized incoherent light the order becomes isotropic, horizontal, onion, radial, and vertical.

  16. Cavitation bubble behavior inside a liquid jet

    NASA Astrophysics Data System (ADS)

    Robert, Etienne; Lettry, Jacques; Farhat, Mohamed; Monkewitz, Peter A.; Avellan, François

    2007-06-01

    The growth and collapse of laser-induced vapor cavities inside axisymmetric free-falling liquid water jets have been studied. Bubbles of different size are generated at various distances from the jet axis and the effects on the jet interface are recorded by means of ultrafast cinematography. The configuration is characterized by two dimensionless parameters: the bubble to jet diameter ratio δ and the eccentricity coefficient ɛ defined as the radius of bubble generation divided by the jet radius. For high δ and ɛ, microjets and droplets are ejected from the liquid jet at speeds exceeding 100m/s. The observed jet fragmentation shows similarities with experiments conducted on a liquid mercury jet hit by a pulsed proton beam, a candidate configuration for future accelerator based facilities.

  17. Probing Magnetized Turbulence in the Fermi Bubbles

    NASA Astrophysics Data System (ADS)

    Lund, Kelsey; Hales, Christopher A.; Su, Meng

    2017-01-01

    Fermi-LAT observations have revealed giant, sharply defined gamma-ray structures emanating from the Galactic center known as the Fermi bubbles. They extend ~50 degrees (~8.5 kpc) above and below the plane of the Milky Way. Their origin is uncertain but thought to be related to an energetic event such as accretion onto Sgr A* or a burst of nuclear star formation. We analyzed archival radio measurements of Faraday rotation toward extragalactic sources and detected a signature of the bubbles at the shock boundary to the Galactic halo. To confirm these preliminary findings we performed new radio observations with the Karl G. Jansky Very Large Array (JVLA). We discuss the findings of our observations, the shock energetics of the bubbles and their implications for nuclear Galactic activity.

  18. Topological vacuum bubbles by anyon braiding

    PubMed Central

    Han, Cheolhee; Park, Jinhong; Gefen, Yuval; Sim, H.-S.

    2016-01-01

    According to a basic rule of fermionic and bosonic many-body physics, known as the linked cluster theorem, physical observables are not affected by vacuum bubbles, which represent virtual particles created from vacuum and self-annihilating without interacting with real particles. Here we show that this conventional knowledge must be revised for anyons, quasiparticles that obey fractional exchange statistics intermediate between fermions and bosons. We find that a certain class of vacuum bubbles of Abelian anyons does affect physical observables. They represent virtually excited anyons that wind around real anyonic excitations. These topological bubbles result in a temperature-dependent phase shift of Fabry–Perot interference patterns in the fractional quantum Hall regime accessible in current experiments, thus providing a tool for direct and unambiguous observation of elusive fractional statistics. PMID:27030442

  19. Space radiation dosimetry using bubble detectors.

    PubMed

    Ing, H; Mortimer, A

    1994-10-01

    Bubble detectors--a new development in radiation detection--has only recently been used for radiation measurements in space. One important characteristic of the bubble detector is that it operates on a phenomenon which bears considerable resemblance to biological response. Recent experimental results from irradiating bubble detectors with high-energy heavy ions point to the need to re-examine the methodology used for assessing space radiation and the relevance of conventional quantities such as dose equivalent for space dosimetry. It may be that biological hazard associated with the intensely ionizing events--associated with nuclear fragmentation but delivering relatively small dose equivalent--may be much more important than that associated with lightly ionizing events which comprise the bulk of the conventional radiation dose equivalent.

  20. Bubble heating in Extreme Cooling Clusters

    NASA Astrophysics Data System (ADS)

    Allen, Steven

    2007-09-01

    Our proposal targets `extreme cooling' clusters: those systems with the largest, fastest cooling rates that most severely challenge the AGN-heating paradigm for cluster cores. By targeting two X-ray bright `extreme cooling cluters' with the clearest radio bubbles in their cores, we seek to establish whether it is possible for AGN heating to balance cooling in such systems. If cooling is not balanced by some heat source, then large residual cooling rates should be detectable in the spectral X-ray data. We will measure the bubble properties precisely and map the spatial-spectral structure of the surrounding X-ray gas, searching for ghost bubbles, shocks, ripples, fronts and non-thermal emission.

  1. The cultivation of Anabaena variabilis in a bubble column operating under bubbly and slug flows.

    PubMed

    Yoon, Jong Hyun; Choi, Shin Sik; Park, Tai Hyun

    2012-04-01

    In a bubble column reactor with an inner diameter of 6cm and a height of 63cm for the culture of cyanobacteria two different shapes of bubbles can be generated, resulting in bubbly flow or slug flow. Growth of Anabaena variabilis under slug flow (1.9g/l/day) was 1.73 times higher than that under bubbly flow (1.1g/l/day) when the specific irradiation rate was maintained above 10μmol/s/g dry cell. Although a stepwise increase in superficial gas velocity enhanced the average cell growth rate under bubbly flow by 1.57 times, the average cell growth rate during the deceleration phase under bubbly flow (1.98g/l/day) was 0.61 times smaller than that under slug flow (3.22g/l/day). These results demonstrate that the bubble shape in the slug flow was advantageous in regards to the radial circulation of cells.

  2. FERMI BUBBLES AND BUBBLE-LIKE EMISSION FROM THE GALACTIC PLANE

    SciTech Connect

    De Boer, Wim; Weber, Markus E-mail: markus.weber2@kit.edu

    2014-10-10

    The diffuse gamma-ray sky revealed ''bubbles'' of emission above and below the Galactic plane, symmetric around the center of the Milky Way, with a height of 10 kpc in both directions. At present, there is no convincing explanation for the origin. To understand the role of the Galactic center, one has to study the bubble spectrum inside the disk, a region that has been excluded from previous analyses because of the large foreground. From a novel template fit, which allows a simultaneous determination of the signal and foreground in any direction, we find that bubble-like emission is not only found in the halo, but in the Galactic plane as well, with a width in latitude coinciding with the molecular clouds. The longitude distribution has a width corresponding to the Galactic bar with an additional contribution from the Scutum-Centaurus arm. The energy spectrum of the bubbles coincides with the predicted contribution from CRs trapped in sources (SCRs). Also, the energetics fits well. Hence, we conclude that the bubble-like emission has a hadronic origin that arises from SCRs, and the bubbles in the halo arise from hadronic interactions in advected gas. Evidence for advection is provided by the ROSAT X-rays of hot gas in the bubble region.

  3. Formation and X-ray emission from hot bubbles in planetary nebulae - I. Hot bubble formation

    NASA Astrophysics Data System (ADS)

    Toalá, J. A.; Arthur, S. J.

    2014-10-01

    We carry out high-resolution two-dimensional radiation-hydrodynamic numerical simulations to study the formation and evolution of hot bubbles inside planetary nebulae. We take into account the evolution of the stellar parameters, wind velocity and mass-loss rate from the final thermal pulses during the asymptotic giant branch (AGB) through to the post-AGB stage for a range of initial stellar masses. The instabilities that form at the interface between the hot bubble and the swept-up AGB wind shell lead to hydrodynamical interactions, photoevaporation flows and opacity variations. We explore the effects of hydrodynamical mixing combined with thermal conduction at this interface on the dynamics, photoionization, and emissivity of our models. We find that even models without thermal conduction mix significant amounts of mass into the hot bubble. When thermal conduction is not included, hot gas can leak through the gaps between clumps and filaments in the broken swept-up AGB shell and this depressurises the bubble. The inclusion of thermal conduction evaporates and heats material from the clumpy shell, which expands to seal the gaps, preventing a loss in bubble pressure. The dynamics of bubbles without conduction is dominated by the thermal pressure of the thick photoionized shell, while for bubbles with thermal conduction it is dominated by the hot, shocked wind.

  4. Wolf-Rayet Bubbles. I. Analytic Solutions

    NASA Astrophysics Data System (ADS)

    Garcia-Segura, Guillermo; Mac Low, Mordecai-Mark

    1995-12-01

    Stellar wind bubble dynamics are sensitive to the stellar wind velocity and mass-loss history. Observations of ring nebulae can thus strongly constrain theories of stellar winds and massive stellar evolution. Furthermore, ring nebulae are often observed around Wolf-Rayet stars likely to soon become supernovae, so their influence on the circumstellar medium is vital to understanding young supernova remnants such as Cas A. To interpret the observations, the connection between the input wind and the observed gas distribution must be described. This is our goal in this series of papers. In this paper, we present analytic solutions for the dynamics of bubbles expanding into media with power-law density distributions such as r-2. We apply the solutions to Wolf-Rayet bubbles expanding into red supergiant winds. A semianalytic method is used to model aspherical bubbles resulting from nonspherical red supergiant winds. Applying this method, we find, for the case of steady winds, that bubbles expand at nearly constant velocity in each direction, keeping their shapes. We can then make the approximation that the bubbles have constant-eccentricity ellipsoidal shapes to derive a fully analytic dynamical model. From this we derive solutions for the diffuse X-ray luminosities from steady winds, using the assumption of classical conductive evaporation. Useful relationships between observables are also given. The solutions are compared to observations of the Wolf-Rayet ring nebula NGC 6888. We find that with either the assumption of energy conservation or momentum conservation, the dynamics of this nebula cannot be explained if the reported wind kinetic energy of the central star WR 136 is used. The nebular kinematics require an order of magnitude less effective mechanical luminosity from WR 136, demanding a lower mass-loss rate, a lower wind velocity, or both.

  5. Acoustical bubble trapper applied to hemodialysis.

    PubMed

    Palanchon, P; Birmelé, B; Tranquart, F

    2008-04-01

    Gaseous microemboli can arise in extracorporeal lines and devices such as dialysis machines. They are associated with severe pulmonary side effects in patients undergoing chronic hemodialysis sessions. The goal of this study was to develop a gaseous emboli trapper using ultrasound waves to remove any air bubble from the tubing system before they reach the patient. A homemade bubble trapper, developed in the laboratory, consists of a Perspex block containing a main channel connected to the tubing of a hemodialysis machine and a second subchannel positioned perpendicularly to the main one, used to trap the air microemboli. The microemboli flowing in the main channel were insonified through an acoustic window with an ultrasound wave, at a frequency of 500 kHz and with a maximal acoustic pressure of 500 kPa, generated by a single-element transducer positioned 3 cm away from the main flow. The radiation force induced by the ultrasound beam acts directly on the flowing air emboli, by pushing them into the subchannel. Two Doppler probes operating both at 2 MHz, connected to a DWL Doppler machine were placed before and after the bubble trapper to count sequentially the number of embolic events. The flow of the machine was varied between 200 mL/min and 500 mL/min. Depending on the flow velocity, the number of microembolic signals (MES) detected by the Doppler probes before and after the trapping system was identical and ranged from 5 to 150 MES/min in absence of the ultrasound irradiation. When the air bubble trapper was activated, a reduction of the number of MES, up to 70%, was achieved. Doppler recordings suggest that the circulating bubbles were either fragmented into smaller bubble fragments or directly got pushed into the second subchannel where they were collected. This simple approach using an ultrasound-based trapping system was shown to operate adequately with the current settings and can be used to filter air microemboli.

  6. Hadron bubble evolution into the quark sea

    SciTech Connect

    Freese, K. ); Adams, F.C. )

    1990-04-15

    A solution is presented for the evolution of hadron bubbles which nucleate in the quark sea if there is a first-order quark-hadron phase transition at a temperature {ital T}{sub {ital c}} on the order of 100 MeV. We make three assumptions: (1) the dominant mechanism for transport of latent heat is radiative, e.g., neutrinos; (2) the distance between nucleation sites is greater than the neutrino mean free path; and (3) the effects of hydrodynamic flow can be neglected. Bubbles nucleate with a characteristic radius 1 fm/{Delta}, where {Delta} is a dimensionless parameter for the undercooling (we take {Delta}{ge}10{sup {minus}4}, so that the expansion of the Universe can be neglected). We argue that bubbles grow stably and remain spherical until the radius becomes as large as the neutrino mean free path, {ital l}{congruent}10 cm. The growth then becomes diffusion limited and the bubbles become unstable to formation of dendrites, or fingerlike structures, because latent heat can diffuse away more easily from long fingers than from spheres. We study the nonlinear evolution of structure with a geometrical model'' and argue that the hadron bubbles ultimately look like stringy seaweed. The percolation of seaweed-shaped bubbles can leave behind regions of quark phase that are quite small. In fact, one might expect the typical scale to be {ital L}{sub {ital Q}}={ital l}{congruent}10 cm. Protons can easily diffuse out of such small regions (and neutrons back in). Thus, these instabilities can lead to important modifications of inhomogeneous nucleosynthesis, which requires {ital L}{sub {ital Q}}{approx gt}1 m.

  7. The biology of trauma: implications for treatment.

    PubMed

    Solomon, Eldra P; Heide, Kathleen M

    2005-01-01

    During the past 20 years, the development of brain imaging techniques and new biochemical approaches has led to increased understanding of the biological effects of psychological trauma. New hypotheses have been generated about brain development and the roots of antisocial behavior. We now understand that psychological trauma disrupts homeostasis and can cause both short and long-term effects on many organs and systems of the body. Our expanding knowledge of the effects of trauma on the body has inspired new approaches to treating trauma survivors. Biologically informed therapy addresses the physiological effects of trauma, as well as cognitive distortions and maladaptive behaviors. The authors suggest that the most effective therapeutic innovation during the past 20 years for treating trauma survivors has been Eye Movement Desensitization and Reprocessing (EMDR), a therapeutic approach that focuses on resolving trauma using a combination of top-down (cognitive) and bottom-up (affect/body) processing.

  8. Line emission in single-bubble sonoluminescence.

    PubMed

    Young, J B; Nelson, J A; Kang, W

    2001-03-19

    We report that single-bubble sonoluminescence (SBSL) at low light intensities produces emission bands similar to multibubble sonoluminescence (MBSL) for pure noble gas bubbles. A smooth crossover between SBSL and MBSL behavior can be induced by varying the acoustic pressure amplitude and thereby the intensity of the light emitted. The relative intensity of the band emission depends both on the molecular weight of the noble gas and the water temperature. Our results provide a connection between the mechanisms SBSL and MBSL and show that molecular emission plays a role in SBSL.

  9. Line Emission in Single-Bubble Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Young, Joseph B.; Nelson, Jeffrey A.; Kang, Woowon

    2001-03-01

    We report that single-bubble sonoluminescence (SBSL) at low light intensities produces emission bands similar to multibubble sonoluminescence (MBSL) for pure noble gas bubbles. A smooth crossover between SBSL and MBSL behavior can be induced by varying the acoustic pressure amplitude and thereby the intensity of the light emitted. The relative intensity of the band emission depends both on the molecular weight of the noble gas and the water temperature. Our results provide a connection between the mechanisms SBSL and MBSL and show that molecular emission plays a role in SBSL.

  10. A large bubble around the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Romani, Roger W.; Reach, William T.; Koo, Bon Chul; Heiles, Carl

    1990-01-01

    IRAS and 21 cm observations of the interstellar medium around the Crab nebula show evidence of a large bubble surrounded by a partial shell. If located at the canonical 2 kpc distance of the Crab pulsar, the shell is estimated to have a radius of about 90 pc and to contain about 50,000 solar masses of swept-up gas. The way in which interior conditions of this bubble can have important implications for observations of the Crab are described, and the fashion in which presupernova evolution of the pulsar progenitor has affected its local environment is described.

  11. Implementing a bubble memory hierarchy system

    NASA Technical Reports Server (NTRS)

    Segura, R.; Nichols, C. D.

    1979-01-01

    This paper reports on implementation of a magnetic bubble memory in a two-level hierarchial system. The hierarchy used a major-minor loop device and RAM under microprocessor control. Dynamic memory addressing, dual bus primary memory, and hardware data modification detection are incorporated in the system to minimize access time. It is the objective of the system to incorporate the advantages of bipolar memory with that of bubble domain memory to provide a smart, optimal memory system which is easy to interface and independent of user's system.

  12. Gas Bubble Growth in Muddy Sediments

    DTIC Science & Technology

    2000-09-30

    the ebullitive flux of methane, an important “greenhouse gas”, to the atmosphere. OBJECTIVES The immediate objective is a working model for the growth...OMB control number. 1. REPORT DATE SEP 2000 2. REPORT TYPE 3. DATES COVERED 00-00-2000 to 00-00-2000 4. TITLE AND SUBTITLE Gas Bubble Growth in...N is the porosity, D is the tortuosity-corrected diffusivity, cg is the concentration of gas in the bubble, S is the local rate of methanogenesis, R1

  13. Mass transfer effects on the transmission of bubble screens

    NASA Astrophysics Data System (ADS)

    Fuster, Daniel; Bergamasco, Luca

    2016-11-01

    In this work we investigate, theoretically and numerically, the reflection and transmission properties of bubble screens excited by pressure wave pulses. We use modified expressions for the bubble resonance frequency and the damping factor in order to capture the influence of mass transfer on the reflection-transmission coefficients. In addition to the influence of variables such as the bubble radius and the averaged inter-bubble distance, the analysis reveals that in conditions close to the saturation line there exists a regime where the heat transport surrounding the bubble plays an important role on the bubble's response also influencing the reflection properties of the bubble screen. The linear analysis allows us to predict the critical vapor content beyond which liquid heat's transport controls the dynamic response of the bubbles. Numerical simulations show that these effects become especially relevant in the nonlinear regime. ANR Cachmap.

  14. When Do Bubbles Cause a Floating Body To Sink?

    ERIC Educational Resources Information Center

    Denardo, Bruce; Pringle, Leonard; DeGrace, Carl; McGuire, Michael

    2001-01-01

    Describes qualitative lecture demonstrations that show that bubbles can indeed sink a body, including the case of ice in water. Presents a quantitative experiment to determine the density of bubbly water required to sink a spherical body. (Author/YDS)

  15. Nonlinear dynamics of laser-induced bubble near elastic boundaries

    NASA Astrophysics Data System (ADS)

    Liu, Xiu Mei; He, Jie; Lu, Jian; Ni, Xiao Wu

    2008-01-01

    Nonlinear dynamics of a laser-generated single cavitation bubble near an elastic boundary is investigated by a fiber-optic diagnostic technique based on optical beam deflection (OBD). The maximum bubble radii and the bubble life-time for each oscillation cycle are determined according to the characteristic signals. It is shown that with the increase of the number of oscillating cycles, the maximum radii and the life-time of the bubble are decreased sharply. Furthermore, the effect of material elasticity on nonlinear dynamics of cavitation bubble has also been investigated in some detail. The maximum bubble size and thus the bubble life time decreases with an increase in elastic modulus. In addition, increasing elastic modulus leads to a significant decrease of the collapse amplitude and the bubble energy. These results are valuable in the fields of cavitation erosion, collateral damage in laser surgery, and cavitation-mediated enhancement of pulsed laser ablation of tissue.

  16. Simulations of Bubble Motion in an Oscillating Liquid

    NASA Astrophysics Data System (ADS)

    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.

  17. Blowing Bubbles: An Interdisciplinary Science and Mathematics Lab.

    ERIC Educational Resources Information Center

    Stallings, Lynn; Wimpey, Kim

    2000-01-01

    Introduces a bubble activity to teach about the nature of molecules, surface tension, light waves, and color. Explains how to make the bubble solution and includes a lab worksheet with answers to the questions. (YDS)

  18. Interfacial Charge Effects on Sticky Bubble Morphology in a Microchannel

    NASA Astrophysics Data System (ADS)

    Hui, Jonathan; Huang, Peter

    2015-11-01

    Many multiphase fluidic processes in small conduits, such as petroleum extraction and biochemical analysis, can encounter disastrous flow blockages due to the lodging of immiscible bubbles or droplets. The complete drainage of a thin-film lubrication layer surrounding an adhered bubble demands a significantly higher threshold pressure gradient in order to reinitiate bulk flows. In this work, we investigate bubble morphology due to the lubrication layer drainage process that results in bubble adhesion and study how an electrostatically charged bubble interface and charged channel wall may affect bubble morphology in preventing bubble adhesion. We report on our multiphysics computational analysis of an oversized gas bubble in a water-filled microchannel under the influence of surface tension and interfacial electrostatic forces. Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund for support of this research.

  19. Do unbounded bubbles ultimately become fenced inside a black hole?

    SciTech Connect

    Guzman, F. S.; Sarbach, O.; Lehner, L.

    2007-09-15

    We examine the dynamical behavior of recently introduced bubbles in asymptotically flat, five-dimensional spacetimes. Using numerical methods, we find that even bubbles that initially start expanding eventually collapse to a Schwarzschild-Tangherlini black hole.

  20. [Safe:Trac course series of the German Society for Trauma Surgery on patient safety].

    PubMed

    Burghofer, K; Lackner, C K

    2009-08-01

    Based on crew resource management of the airline industry the German Society for Trauma Surgery (Deutsche Gesellschaft für Unfallchirurgie, DGU) was the first scientific community in Germany to develop and implement a training course for patient safety. The S:training courses contain four course formats which focus on the prehospital life support (S:PLS), the operating room (S:OR), the trauma room (S:TR) and the intensive care unit (S:ICU). In the training the importance of the human factor for the management of acute major trauma is developed by means of presentations, training videos, practical training, discussions and realistic case scenarios associated with the special working environment of the participants. A specially developed course manual acts as a work and reference book and course booking is possible at http://www.safe-trac.de.

  1. Boundary Integral Technique for Explosion Bubble Collapse Analysis

    DTIC Science & Technology

    1993-08-01

    34 Applied Scientific Research, vol. 38, pp. 145-164, 1982a. 37 1p Prosperetti, A. "A Generalization of the Rayleigh Plesset Equation of Bubble Dynamics...Dispersed Two - Phase Flow." Journal of Multiphase Flow, vol. 10, no. 4, pp. 425-444, 1984. Prosperetti, A., and A. Lezzi. "Bubble Dynamics in a Compressible...oscillating system. This process is termed bubble pulsation. During the contraction phase of the bubble pulsation, variations in the surrounding fluid pressure

  2. Spherical bubble motion in a turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Felton, Keith; Loth, Eric

    2001-09-01

    Monodisperse dilute suspensions of spherical air bubbles in a tap-water turbulent vertical boundary layer were experimentally studied to note their motion and distribution. Bubbles with diameters of 0.37-1.2 mm were injected at various transverse wall-positions for free-stream velocities between 0.4 and 0.9 m/s. The bubbles were released from a single injector at very low frequencies such that two-way coupling and bubble-bubble interaction were negligible. The experimental diagnostics included ensemble-averaged planar laser intensity profiles for bubble concentration distribution, as well as Cinematic Particle Image Velocimetry with bubble tracking for bubble hydrodynamic forces. A variety of void distributions within the boundary layer were found. For example, there was a tendency for bubbles to collect along the wall for higher Stokes number conditions, while the lower Stokes number conditions produced Gaussian-type profiles throughout the boundary layer. In addition, three types of bubble trajectories were observed—sliding bubbles, bouncing bubbles, and free-dispersion bubbles. Instantaneous liquid forces acting on individual bubbles in the turbulent flow were also obtained to provide the drag and lift coefficients (with notable experimental uncertainty). These results indicate that drag coefficient decreases with increasing Reynolds number as is conventionally expected but variations were observed. In general, the instantaneous drag coefficient (for constant bubble Reynolds number) tended to be reduced as the turbulence intensity increased. The averaged lift coefficient is higher than that given by inviscid theory (and sometimes even that of creeping flow theory) and tends to decrease with increasing bubble Reynolds number.

  3. Relative acoustic frequency response of induced methane, carbon dioxide and air gas bubble plumes, observed laterally.

    PubMed

    Kubilius, Rokas; Pedersen, Geir

    2016-10-01

    There is an increased need to detect, identify, and monitor natural and manmade seabed gas leaks. Fisheries echosounders are well suited to monitor large volumes of water and acoustic frequency response [normalized acoustic backscatter, when a measure at one selected frequency is used as a denominator, r(f)] is commonly used to identify echoes from fish and zooplankton species. Information on gas plume r(f) would be valuable for automatic detection of subsea leaks and for separating bubble plumes from natural targets such as swimbladder-bearing fish. Controlled leaks were produced with a specially designed instrument frame suspended in mid-water in a sheltered fjord. The frame was equipped with echosounders, stereo-camera, and gas-release nozzles. The r(f) of laterally observed methane, carbon dioxide, and air plumes (0.040-29 l/min) were measured at 70, 120, 200, and 333 kHz, with bubble sizes determined optically. The observed bubble size range (1-25 mm) was comparable to that reported in the literature for natural cold seeps of methane. A negative r(f) with increasing frequency was observed, namely, r(f) of about 0.7, 0.6, and 0.5 at 120, 200, and 333 kHz when normalized to 70 kHz. Measured plume r(f) is also compared to resolved, single bubble target strength-based, and modeled r(f).

  4. The Focused Assessment With Sonography For Trauma (FAST) Examination And Pelvic Trauma: Indications And Limitations.

    PubMed

    Shaukat, Nadia Maria; Copeli, Nikolai; Desai, Poonam

    2016-03-01

    Pelvic trauma accounts for only 3% of all skeletal injuries but may have mortality as high as 45% in cases of severe trauma. Significant high-grade-mechanism trauma to the pelvis must always take the abdomen into consideration for evaluation. The focused assessment with sonography for trauma (FAST) examination has been shown to be a valuable tool in assessing the unstable trauma patient with blunt abdominal injury, though its diagnostic utility is much less well-defined than in primary pelvic trauma. This systematic review explores the utility and limitations of the FAST examination in patients with blunt pelvic trauma and discusses the timing for the examination during the trauma survey. Newer techniques for emergency department management of the unstable trauma patient are also addressed.

  5. A proposed algorithm for multimodal liver trauma management from a surgical trauma audit in a western European trauma center.

    PubMed

    Di Saverio, S; Sibilio, A; Coniglio, C; Bianchi, E; Biscardi, A; Villani, S; Gordini, G; Tugnoli, G

    2014-11-01

    Management of liver trauma is challenging and may vary widely given the heterogeneity of liver injuries' anatomical configuration, the hemodynamic status, the settings and resources available. Perhaps the use of non-operative management (NOM) may have potential drawbacks and the role of damage control surgery (DCS) and angioembolization represents a major evolving concept.1 Most severe liver trauma in polytrauma patients accounts for a significant morbidity and mortality. Major liver trauma with extensive parenchymal injury and uncontrollable bleeding is therefore a challenge for the trauma team. However a safe and effective surgical hemostasis and a carefully planned multidisciplinary approach can improve the outcome of severe liver trauma. The technique of perihepatic packing, according to DCS approach, is often required to achieve fast, early and effective control of hemorrhage in the highest grades of liver trauma and in unstable patients. A systematic and standardized technique of perihepatic packing may contribute to improve hemostatic efficacy and overall outcomes if wisely combined in a stepwise "sandwich" multimodal approach. DCS philosophy evolved alongside with damage control resuscitation (DCR) in the management of trauma patients, requiring close interaction between surgery and resuscitation. Therefore, as a result of a combined surgical and critical care clinical audit activity in our western European trauma center, a practical algorithm for multimodal sequential management of liver trauma has been developed based on a historical cohort of 253 liver trauma patients and subsequently validated on a prospective cohort of 135 patients in the period 2010-2013.

  6. Interactions of mid-infrared bubbles with the interstellar medium: are bubble rims associated with collapsing cores?

    NASA Astrophysics Data System (ADS)

    Devine, Kathryn E.; Mori, Johanna; Watson, Christer

    2017-01-01

    Mid-infrared bubbles expanding into the interstellar medium (ISM) are often proposed as a trigger for subsequent star formation, although the mechanisms of this triggering are not well understood. Better observational data of the ISM near bubbles can elucidate the connection between bubbles and nearby star formation. We used the VEGAS spectrometer on the Green Bank Telescope to simultaneously observe several Q-band emission lines between 45-49 GHz. We detected HC3N, C34S, CH3OH, and CS toward four mid-infrared (MIR) bubbles. Two of the bubbles are spatially coincident with dark filaments. We show that in both of these cases, the bubbles do not appear to be causing infall in the filaments. We also present the gas kinematics toward two gas clumps coincident with bubble rims. Both clumps show evidence of infall. Finally, we present trends seen in the chemical abundances relative to the bubble.

  7. Acoustic Model of the Remnant Bubble Cloud from Underwater Explosion

    DTIC Science & Technology

    2012-11-01

    model provided by Geers&Hunter (2002). lg cc , 21, ff ∞p 3, f 4f Initial conditions for equation (1) are obtained from combina- tion of similitude ...variation of bubble depth with time depending on the initial bubble size. Mathematically , we can describe the bubble trajectories by the following equa

  8. Rhetoric, Risk, and Markets: The Dot-Com Bubble

    ERIC Educational Resources Information Center

    Goodnight, G. Thomas; Green, Sandy Edward, Jr.

    2010-01-01

    Post-conventional economic theories are assembled to inquire into the contingent, mimetic, symbolic, and material spirals unfolding the dot-com bubble, 1992-2002. The new technologies bubble is reconstructed as a rhetorical movement across the practices of the hybrid market-industry risk culture of communications. The legacies of the bubble task…

  9. A mathematical definition of the financial bubbles and crashes

    NASA Astrophysics Data System (ADS)

    Watanabe, Kota; Takayasu, Hideki; Takayasu, Misako

    2007-09-01

    We check the validity of the mathematical method of detecting financial bubbles or crashes, which is based on a data fitting with an exponential function. We show that the period of a bubble can be determined nearly uniquely independent of the precision of data. The method is widely applicable for stock market data such as the Internet bubble.

  10. Bubble-Free Containers For Liquids In Microgravity

    NASA Technical Reports Server (NTRS)

    Kornfeld, Dale M.; Antar, Basil L.

    1995-01-01

    Reports discuss entrainment of gas bubbles during handling of liquids in microgravity, and one report proposes containers filled with liquids in microgravity without entraining bubbles. Bubbles are troublesome in low-gravity experiments - particularly in biological experiments. Wire-mesh cage retains liquid contents without solid wall, because in microgravity, surface tension of liquid exerts sufficient confining force.

  11. Reducing bubbles in glass coatings improves electrical breakdown strength

    NASA Technical Reports Server (NTRS)

    Banks, B.

    1968-01-01

    Helium reduces bubbles in glass coatings of accelerator grids for ion thrustors. Fusing the coating in a helium atmosphere creates helium bubbles in the glass. In an argon atmosphere, entrapped helium diffuses out of the glass and the bubbles collapse. The resultant coating has a substantially enhanced electrical breakdown strength.

  12. Experimental study on wake structure of single rising clean bubble

    NASA Astrophysics Data System (ADS)

    Sato, Ayaka; Takedomi, Yuta; Shirota, Minori; Sanada, Toshiyuki; Watanabe, Masao

    2007-11-01

    Wake structure of clean bubble rising in quiescent silicone oil solution of photochromic dye is experimentally studied. A single bubble is generated, immediately after UV sheet light illuminates the part of the liquid just above the bubble generation nozzle in order to activate photochromic dye. Once the bubble passes across the colored part of the liquid, the bubble is accompanied by some portion of activated dye tracers; hence the flow structure in the rear of the single rising bubble is visualized. We capture stereo images of both wake structure and bubble motion. We study how wake structure changes with the increase in bubble size. We observe the stable axisymmetric wake structure, which is called `standing eddy' when bubble size is relatively small, and then wake structure becomes unstable and starts to oscillate with the increase in bubble size. With further increase in bubble size, a pair of streamwise vortices, which is called `double thread', is observed. We discuss in detail this transition from the steady wake to unsteady wake structure, especially double thread wake development and hairpin vortices shedding, in relation to the transition from rectilinear to spiral or zigzag bubble motions.

  13. Assessment and Availability of Trauma Care Services in a District Hospital of South India; A Field Observational Study

    PubMed Central

    Uthkarsh, Pallavi Sarji; Gururaj, Gopalkrishna; Reddy, Sai Sabharish; Rajanna, Mandya Siddalingaiah

    2016-01-01

    Objective: To assess the availability of trauma care services in a district referral hospital of Southern India. Methods: This was a cross-sectional study being performed during 2013 in a tertiary healthcare centre in Southern Indian. A detailed assessment of trauma care services was done in a 400 bed speciality hospital which is an apex referral hospital in the public health system using a check list based on WHO guidelines for evaluation of essential trauma care services, along with in-depth interviews of hospital stake holders and key informants. Results: The hospital had physical infrastructure in terms of emergency room, inpatient wards, operation theatres, intensive care unit and blood bank facilities. The recently constructed designated building for trauma care services was not operational and existing facilities were used beyond capacity. A designated trauma team was lacking and speciality services for managing polytrauma were deficient and thus, existing personnel were performing multiple tasks. Neurosurgeons and rehabilitative nursing staff were unavailable, and a radiographer was not available on a 24/7 basis. Existing nursing personnel had not received any formal training in trauma care and standard operating protocols were not available for trauma care. Resources for acute resuscitation were partially adequate. The hospital lacked adequate resources to manage head, abdomen, chest and spine injuries, and most of the polytrauma cases were referred to nearby city hospitals. Conclusion: District hospital, the only referral hospital in public health system for trauma victims of that region, had inadequate resources to manage trauma victims, which was probably responsible for delay in trauma care, improper referrals, high cost of care and poor outcomes. PMID:27331066

  14. Hypotensive Resuscitation among Trauma Patients

    PubMed Central

    Carrick, Matthew M.; Leonard, Jan; Slone, Denetta S.; Mains, Charles W.

    2016-01-01

    Hemorrhagic shock is a principal cause of death among trauma patients within the first 24 hours after injury. Optimal fluid resuscitation strategies have been examined for nearly a century, more recently with several randomized controlled trials. Hypotensive resuscitation, also called permissive hypotension, is a resuscitation strategy that uses limited fluids and blood products during the early stages of treatment for hemorrhagic shock. A lower-than-normal blood pressure is maintained until operative control of the bleeding can occur. The randomized controlled trials examining restricted fluid resuscitation have demonstrated that aggressive fluid resuscitation in the prehospital and hospital setting leads to more complications than hypotensive resuscitation, with disparate findings on the survival benefit. Since the populations studied in each randomized controlled trial are slightly different, as is the timing of intervention and targeted vitals, there is still a need for a large, multicenter trial that can examine the benefit of hypotensive resuscitation in both blunt and penetrating trauma patients. PMID:27595109

  15. Musculoskeletal trauma: the baseball bat.

    PubMed Central

    Bryant, D. D.; Greenfield, R.; Martin, E.

    1992-01-01

    Between July 1987 and December 1990 in Washington, DC, 116 patients sustained 146 fractures and seven dislocations due to an assault with a baseball bat. The ulna was the most common site of trauma (61 fractures), followed by the hand (27 injuries) and the radius (14 injuries). Forty-two of the 146 fractures were significantly displaced and required open reduction and internal fixation to restore satisfactory alignment. Twenty-nine of the 146 fractures were open fractures. Treatment protocol for open fractures consisted of irrigation and debridement, antibiotic therapy, and bone stabilization with either internal or external fixation, or casting. Recognition of the severity of the soft tissue and bone damage is important in the management of musculoskeletal trauma secondary to the baseball bat. Images Figure 1 Figure 2 Figure 3 PMID:1460683

  16. Planned reoperation for severe trauma.

    PubMed Central

    Hirshberg, A; Mattox, K L

    1995-01-01

    OBJECTIVE: The authors review the physiologic basis, indications, techniques, and results of the planned reoperation approach to severe trauma. SUMMARY BACKGROUND DATA: Multivisceral trauma and exsanguinating hemorrhage lead to hypothermia, coagulopathy, and acidosis. Formal resections and reconstructions in these unstable patients often result in irreversible physiologic insult. A new surgical strategy addresses these physiologic concerns by staged control and repair of the injuries. METHOD: The authors review the literature. RESULTS: Indications for planned reoperation include avoidance of irreversible physiologic insult and inability to obtain direct hemostasis or formal abdominal closure. The three phases of the strategy include initial control, stabilization, and delayed reconstruction. Various techniques are used to obtain rapid temporary control of bleeding and hollow visceral spillage. Hypothermia, coagulopathy, and the abdominal compartment syndrome are major postoperative concerns. Definitive repair of the injuries is undertaken after stabilization. CONCLUSION: Planned reoperation offers a simple and effective alternative to the traditional surgical management of complex or multiple injuries in critically wounded patients. PMID:7618965

  17. Effective teamwork in trauma management.

    PubMed

    Frakes, Patricia; Neely, Iain; Tudoe, Robert

    2009-12-01

    The emergency department (ED) education team at the Queen's Medical Centre, Nottingham, has developed a process to promote effective teamwork in major trauma management. To introduce this process to ED staff, the team developed a multiprofessional education and training programme. This article describes the development process, explains how and why it was undertaken, and provides details of the education and training programme. It also highlights the challenges met by the education team during implementation.

  18. Transfusion Practice in Military Trauma

    DTIC Science & Technology

    2008-01-01

    15 patients including several who were shot, others who were severely injured in other ways and four who ultimately died. Despite the small number...their most profound social consequences in the loss of young adults from the working population. Injury is the most common cause of the loss of years...who have an injury severity score of > 15 and must have a trauma surgeon, anaesthesiologist, orthopaedic surgeon, thoracic surgeon and neurosurgeon

  19. Fibrinogen Metabolic Responses to Trauma

    DTIC Science & Technology

    2009-01-13

    intravascular coagulation (DIC), and thrombotic complications [8,10-12]. Based on the limited data avail- able at present, changes in fibrinogen...water at 4°C [48]. Temperature of 32°C was used based on the fact that 100% mortality was observed when the temperature in trauma patients dropped...study. The amount of fibrinogen transfused was calculated based on fibrinogen amount within each blood product, such as fresh whole blood

  20. Current Epidemiology of Genitourinary Trauma

    PubMed Central

    McGeady, James B.; Breyer, Benjamin N.

    2013-01-01

    Synopsis This article reviews recent publications evaluating the current epidemiology of urologic trauma. It begins by providing a brief explanation of databases that have been recently used to study this patient population, then proceeds to discuss each genitourinary organ individually, discussing the most relevant and up to date information published for each one. The conclusion of the article briefly discusses possible future research and development areas pertaining to the topic. PMID:23905930